This is openocd.info, produced by makeinfo version 6.8 from
openocd.texi.

This User's Guide documents release 0.11.0+dev, dated 25 March 2022, of
the Open On-Chip Debugger (OpenOCD).

   * Copyright (C) 2008 The OpenOCD Project
   * Copyright (C) 2007-2008 Spencer Oliver <spen@spen-soft.co.uk>
   * Copyright (C) 2008-2010 Oyvind Harboe <oyvind.harboe@zylin.com>
   * Copyright (C) 2008 Duane Ellis <openocd@duaneellis.com>
   * Copyright (C) 2009-2010 David Brownell

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.2 or any later version published by the Free Software
     Foundation; with no Invariant Sections, no Front-Cover Texts, and
     no Back-Cover Texts.  A copy of the license is included in the
     section entitled "GNU Free Documentation License".
INFO-DIR-SECTION Development
START-INFO-DIR-ENTRY
* OpenOCD: (openocd).      OpenOCD User's Guide
END-INFO-DIR-ENTRY


File: openocd.info,  Node: Top,  Next: About,  Up: (dir)

OpenOCD User's Guide
********************

This User's Guide documents release 0.11.0+dev, dated 25 March 2022, of
the Open On-Chip Debugger (OpenOCD).

   * Copyright (C) 2008 The OpenOCD Project
   * Copyright (C) 2007-2008 Spencer Oliver <spen@spen-soft.co.uk>
   * Copyright (C) 2008-2010 Oyvind Harboe <oyvind.harboe@zylin.com>
   * Copyright (C) 2008 Duane Ellis <openocd@duaneellis.com>
   * Copyright (C) 2009-2010 David Brownell

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.2 or any later version published by the Free Software
     Foundation; with no Invariant Sections, no Front-Cover Texts, and
     no Back-Cover Texts.  A copy of the license is included in the
     section entitled "GNU Free Documentation License".

* Menu:

* About::                            About OpenOCD
* Developers::                       OpenOCD Developer Resources
* Debug Adapter Hardware::           Debug Adapter Hardware
* About Jim-Tcl::                    About Jim-Tcl
* Running::                          Running OpenOCD
* OpenOCD Project Setup::            OpenOCD Project Setup
* Config File Guidelines::           Config File Guidelines
* Server Configuration::             Server Configuration
* Debug Adapter Configuration::      Debug Adapter Configuration
* Reset Configuration::              Reset Configuration
* TAP Declaration::                  TAP Declaration
* CPU Configuration::                CPU Configuration
* Flash Commands::                   Flash Commands
* Flash Programming::                Flash Programming
* PLD/FPGA Commands::                PLD/FPGA Commands
* General Commands::                 General Commands
* Architecture and Core Commands::   Architecture and Core Commands
* JTAG Commands::                    JTAG Commands
* Boundary Scan Commands::           Boundary Scan Commands
* Utility Commands::                 Utility Commands
* GDB and OpenOCD::                  Using GDB and OpenOCD
* Tcl Scripting API::                Tcl Scripting API
* FAQ::                              Frequently Asked Questions
* Tcl Crash Course::                 Tcl Crash Course
* License::                          GNU Free Documentation License

* OpenOCD Concept Index::            Concept Index
* Command and Driver Index::         Command and Driver Index


File: openocd.info,  Node: About,  Next: Developers,  Prev: Top,  Up: Top

About
*****

OpenOCD was created by Dominic Rath as part of a 2005 diploma thesis
written at the University of Applied Sciences Augsburg
(<http://www.hs-augsburg.de>).  Since that time, the project has grown
into an active open-source project, supported by a diverse community of
software and hardware developers from around the world.

What is OpenOCD?
================

The Open On-Chip Debugger (OpenOCD) aims to provide debugging, in-system
programming and boundary-scan testing for embedded target devices.

It does so with the assistance of a "debug adapter", which is a small
hardware module which helps provide the right kind of electrical
signaling to the target being debugged.  These are required since the
debug host (on which OpenOCD runs) won't usually have native support for
such signaling, or the connector needed to hook up to the target.

Such debug adapters support one or more "transport" protocols, each of
which involves different electrical signaling (and uses different
messaging protocols on top of that signaling).  There are many types of
debug adapter, and little uniformity in what they are called.  (There
are also product naming differences.)

These adapters are sometimes packaged as discrete dongles, which may
generically be called "hardware interface dongles".  Some development
boards also integrate them directly, which may let the development board
connect directly to the debug host over USB (and sometimes also to power
it over USB).

For example, a "JTAG Adapter" supports JTAG signaling, and is used to
communicate with JTAG (IEEE 1149.1) compliant TAPs on your target board.
A "TAP" is a "Test Access Port", a module which processes special
instructions and data.  TAPs are daisy-chained within and between chips
and boards.  JTAG supports debugging and boundary scan operations.

There are also "SWD Adapters" that support Serial Wire Debug (SWD)
signaling to communicate with some newer ARM cores, as well as debug
adapters which support both JTAG and SWD transports.  SWD supports only
debugging, whereas JTAG also supports boundary scan operations.

For some chips, there are also "Programming Adapters" supporting special
transports used only to write code to flash memory, without support for
on-chip debugging or boundary scan.  (At this writing, OpenOCD does not
support such non-debug adapters.)

Dongles: OpenOCD currently supports many types of hardware dongles:
USB-based, parallel port-based, and other standalone boxes that run
OpenOCD internally.  *Note Debug Adapter Hardware::.

GDB Debug: It allows ARM7 (ARM7TDMI and ARM720t), ARM9 (ARM920T,
ARM922T, ARM926EJ-S, ARM966E-S), XScale (PXA25x, IXP42x), Cortex-M3
(Stellaris LM3, STMicroelectronics STM32 and Energy Micro EFM32) and
Intel Quark (x10xx) based cores to be debugged via the GDB protocol.

Flash Programming: Flash writing is supported for external
CFI-compatible NOR flashes (Intel and AMD/Spansion command set) and
several internal flashes (LPC1700, LPC1800, LPC2000, LPC4300, AT91SAM7,
AT91SAM3U, STR7x, STR9x, LM3, STM32x and EFM32).  Preliminary support
for various NAND flash controllers (LPC3180, Orion, S3C24xx, more) is
included.

OpenOCD Web Site
================

The OpenOCD web site provides the latest public news from the community:

<http://openocd.org/>

Latest User's Guide:
====================

The user's guide you are now reading may not be the latest one
available.  A version for more recent code may be available.  Its HTML
form is published regularly at:

<http://openocd.org/doc/html/index.html>

PDF form is likewise published at:

<http://openocd.org/doc/pdf/openocd.pdf>

OpenOCD User's Forum
====================

There is an OpenOCD forum (phpBB) hosted by SparkFun, which might be
helpful to you.  Note that if you want anything to come to the attention
of developers, you should post it to the OpenOCD Developer Mailing List
instead of this forum.

<http://forum.sparkfun.com/viewforum.php?f=18>

OpenOCD User's Mailing List
===========================

The OpenOCD User Mailing List provides the primary means of
communication between users:

<https://lists.sourceforge.net/mailman/listinfo/openocd-user>

OpenOCD IRC
===========

Support can also be found on irc: <irc://irc.libera.chat/openocd>


File: openocd.info,  Node: Developers,  Next: Debug Adapter Hardware,  Prev: About,  Up: Top

1 OpenOCD Developer Resources
*****************************

If you are interested in improving the state of OpenOCD's debugging and
testing support, new contributions will be welcome.  Motivated
developers can produce new target, flash or interface drivers, improve
the documentation, as well as more conventional bug fixes and
enhancements.

The resources in this chapter are available for developers wishing to
explore or expand the OpenOCD source code.

1.1 OpenOCD Git Repository
==========================

During the 0.3.x release cycle, OpenOCD switched from Subversion to a
Git repository hosted at SourceForge.  The repository URL is:

<git://git.code.sf.net/p/openocd/code>

or via http

<http://git.code.sf.net/p/openocd/code>

You may prefer to use a mirror and the HTTP protocol:

<http://repo.or.cz/r/openocd.git>

With standard Git tools, use 'git clone' to initialize a local
repository, and 'git pull' to update it.  There are also gitweb pages
letting you browse the repository with a web browser, or download
arbitrary snapshots without needing a Git client:

<http://repo.or.cz/w/openocd.git>

The 'README' file contains the instructions for building the project
from the repository or a snapshot.

Developers that want to contribute patches to the OpenOCD system are
strongly encouraged to work against mainline.  Patches created against
older versions may require additional work from their submitter in order
to be updated for newer releases.

1.2 Doxygen Developer Manual
============================

During the 0.2.x release cycle, the OpenOCD project began providing a
Doxygen reference manual.  This document contains more technical
information about the software internals, development processes, and
similar documentation:

<http://openocd.org/doc/doxygen/html/index.html>

This document is a work-in-progress, but contributions would be welcome
to fill in the gaps.  All of the source files are provided in-tree,
listed in the Doxyfile configuration at the top of the source tree.

1.3 Gerrit Review System
========================

All changes in the OpenOCD Git repository go through the web-based
Gerrit Code Review System:

<https://review.openocd.org/>

After a one-time registration and repository setup, anyone can push
commits from their local Git repository directly into Gerrit.  All users
and developers are encouraged to review, test, discuss and vote for
changes in Gerrit.  The feedback provides the basis for a maintainer to
eventually submit the change to the main Git repository.

The 'HACKING' file, also available as the Patch Guide in the Doxygen
Developer Manual, contains basic information about how to connect a
repository to Gerrit, prepare and push patches.  Patch authors are
expected to maintain their changes while they're in Gerrit, respond to
feedback and if necessary rework and push improved versions of the
change.

1.4 OpenOCD Developer Mailing List
==================================

The OpenOCD Developer Mailing List provides the primary means of
communication between developers:

<https://lists.sourceforge.net/mailman/listinfo/openocd-devel>

1.5 OpenOCD Bug Tracker
=======================

The OpenOCD Bug Tracker is hosted on SourceForge:

<http://bugs.openocd.org/>


File: openocd.info,  Node: Debug Adapter Hardware,  Next: About Jim-Tcl,  Prev: Developers,  Up: Top

2 Debug Adapter Hardware
************************

Defined: dongle: A small device that plugs into a computer and serves as
an adapter ....  [snip]

In the OpenOCD case, this generally refers to a small adapter that
attaches to your computer via USB or the parallel port.

2.1 Choosing a Dongle
=====================

There are several things you should keep in mind when choosing a dongle.

  1. Transport Does it support the kind of communication that you need?
     OpenOCD focuses mostly on JTAG. Your version may also support other
     ways to communicate with target devices.
  2. Voltage What voltage is your target - 1.8, 2.8, 3.3, or 5V? Does
     your dongle support it?  You might need a level converter.
  3. Pinout What pinout does your target board use?  Does your dongle
     support it?  You may be able to use jumper wires, or an "octopus"
     connector, to convert pinouts.
  4. Connection Does your computer have the USB, parallel, or Ethernet
     port needed?
  5. RTCK Do you expect to use it with ARM chips and boards with RTCK
     support (also known as "adaptive clocking")?

2.2 USB FT2232 Based
====================

There are many USB JTAG dongles on the market, many of them based on a
chip from "Future Technology Devices International" (FTDI) known as the
FTDI FT2232; this is a USB full speed (12 Mbps) chip.  See:
<http://www.ftdichip.com> for more information.  In summer 2009, USB
high speed (480 Mbps) versions of these FTDI chips started to become
available in JTAG adapters.  Around 2012, a new variant appeared -
FT232H - this is a single-channel version of FT2232H. (Adapters using
those high speed FT2232H or FT232H chips may support adaptive clocking.)

The FT2232 chips are flexible enough to support some other transport
options, such as SWD or the SPI variants used to program some chips.
They have two communications channels, and one can be used for a UART
adapter at the same time the other one is used to provide a debug
adapter.

Also, some development boards integrate an FT2232 chip to serve as a
built-in low-cost debug adapter and USB-to-serial solution.

   * usbjtag
     Link
     <http://elk.informatik.fh-augsburg.de/hhweb/doc/openocd/usbjtag/usbjtag.html>
   * jtagkey
     See: <http://www.amontec.com/jtagkey.shtml>
   * jtagkey2
     See: <http://www.amontec.com/jtagkey2.shtml>
   * oocdlink
     See: <http://www.oocdlink.com> By Joern Kaipf
   * signalyzer
     See: <http://www.signalyzer.com>
   * Stellaris Eval Boards
     See: <http://www.ti.com> - The Stellaris eval boards bundle
     FT2232-based JTAG and SWD support, which can be used to debug the
     Stellaris chips.  Using separate JTAG adapters is optional.  These
     boards can also be used in a "pass through" mode as JTAG adapters
     to other target boards, disabling the Stellaris chip.
   * TI/Luminary ICDI
     See: <http://www.ti.com> - TI/Luminary In-Circuit Debug Interface
     (ICDI) Boards are included in Stellaris LM3S9B9x Evaluation Kits.
     Like the non-detachable FT2232 support on the other Stellaris eval
     boards, they can be used to debug other target boards.
   * olimex-jtag
     See: <http://www.olimex.com>
   * Flyswatter/Flyswatter2
     See: <http://www.tincantools.com>
   * turtelizer2
     See: Turtelizer 2
     (http://www.ethernut.de/en/hardware/turtelizer/index.html), or
     <http://www.ethernut.de>
   * comstick
     Link: <http://www.hitex.com/index.php?id=383>
   * stm32stick
     Link <http://www.hitex.com/stm32-stick>
   * axm0432_jtag
     Axiom AXM-0432 Link <http://www.axman.com> - NOTE: This JTAG does
     not appear to be available anymore as of April 2012.
   * cortino
     Link <http://www.hitex.com/index.php?id=cortino>
   * dlp-usb1232h
     Link <http://www.dlpdesign.com/usb/usb1232h.shtml>
   * digilent-hs1
     Link <http://www.digilentinc.com/Products/Detail.cfm?Prod=JTAG-HS1>
   * opendous
     Link <http://code.google.com/p/opendous/wiki/JTAG> FT2232H-based
     (OpenHardware).
   * JTAG-lock-pick Tiny 2
     Link <http://www.distortec.com/jtag-lock-pick-tiny-2> FT232H-based

   * GW16042
     Link:
     <http://shop.gateworks.com/index.php?route=product/product&path=70_80&product_id=64>
     FT2232H-based

2.3 USB-JTAG / Altera USB-Blaster compatibles
=============================================

These devices also show up as FTDI devices, but are not
protocol-compatible with the FT2232 devices.  They are, however,
protocol-compatible among themselves.  USB-JTAG devices typically
consist of a FT245 followed by a CPLD that understands a particular
protocol, or emulates this protocol using some other hardware.

They may appear under different USB VID/PID depending on the particular
product.  The driver can be configured to search for any VID/PID pair
(see the section on driver commands).

   * USB-JTAG Kolja Waschk's USB Blaster-compatible adapter
     Link: <http://ixo-jtag.sourceforge.net/>
   * Altera USB-Blaster
     Link: <http://www.altera.com/literature/ug/ug_usb_blstr.pdf>

2.4 USB J-Link based
====================

There are several OEM versions of the SEGGER J-Link adapter.  It is an
example of a microcontroller based JTAG adapter, it uses an AT91SAM764
internally.

   * SEGGER J-Link
     Link: <http://www.segger.com/jlink.html>
   * Atmel SAM-ICE (Only works with Atmel chips!)
     Link: <http://www.atmel.com/tools/atmelsam-ice.aspx>
   * IAR J-Link

2.5 USB RLINK based
===================

Raisonance has an adapter called RLink.  It exists in a stripped-down
form on the STM32 Primer, permanently attached to the JTAG lines.  It
also exists on the STM32 Primer2, but that is wired for SWD and not
JTAG, thus not supported.

   * Raisonance RLink
     Link:
     <http://www.mcu-raisonance.com/~rlink-debugger-programmer__microcontrollers__tool~tool__T018:4cn9ziz4bnx6.html>
   * STM32 Primer
     Link: <http://www.stm32circle.com/resources/stm32primer.php>
   * STM32 Primer2
     Link: <http://www.stm32circle.com/resources/stm32primer2.php>

2.6 USB ST-LINK based
=====================

STMicroelectronics has an adapter called ST-LINK. They only work with
STMicroelectronics chips, notably STM32 and STM8.

   * ST-LINK
     This is available standalone and as part of some kits, eg.
     STM32VLDISCOVERY.
     Link: <http://www.st.com/internet/evalboard/product/219866.jsp>
   * ST-LINK/V2
     This is available standalone and as part of some kits, eg.
     STM32F4DISCOVERY.
     Link: <http://www.st.com/internet/evalboard/product/251168.jsp>
   * STLINK-V3
     This is available standalone and as part of some kits.
     Link: <http://www.st.com/stlink-v3>

For info the original ST-LINK enumerates using the mass storage usb
class; however, its implementation is completely broken.  The result is
this causes issues under Linux.  The simplest solution is to get Linux
to ignore the ST-LINK using one of the following methods:
   * modprobe -r usb-storage && modprobe usb-storage quirks=483:3744:i
   * add "options usb-storage quirks=483:3744:i" to /etc/modprobe.conf

2.7 USB TI/Stellaris ICDI based
===============================

Texas Instruments has an adapter called ICDI. It is not to be confused
with the FTDI based adapters that were originally fitted to their
evaluation boards.  This is the adapter fitted to the Stellaris
LaunchPad.

2.8 USB Nuvoton Nu-Link
=======================

Nuvoton has an adapter called Nu-Link.  It is available either as
stand-alone dongle and embedded on development boards.  It supports SWD,
serial port bridge and mass storage for firmware update.  Both Nu-Link
v1 and v2 are supported.

2.9 USB CMSIS-DAP based
=======================

ARM has released a interface standard called CMSIS-DAP that simplifies
connecting debuggers to ARM Cortex based targets
<http://www.keil.com/support/man/docs/dapdebug/dapdebug_introduction.htm>.

2.10 USB Other
==============

   * USBprog
     Link: <http://shop.embedded-projects.net/> - which uses an Atmel
     MEGA32 and a UBN9604

   * USB - Presto
     Link: <http://tools.asix.net/prg_presto.htm>

   * Versaloon-Link
     Link: <http://www.versaloon.com>

   * ARM-JTAG-EW
     Link: <http://www.olimex.com/dev/arm-jtag-ew.html>

   * Buspirate
     Link: <http://dangerousprototypes.com/bus-pirate-manual/>

   * opendous
     Link: <http://code.google.com/p/opendous-jtag/> - which uses an
     AT90USB162

   * estick
     Link: <http://code.google.com/p/estick-jtag/>

   * Keil ULINK v1
     Link: <http://www.keil.com/ulink1/>

   * TI XDS110 Debug Probe
     Link:
     <https://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_xds110.html>

     Link:
     <https://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_xds_software_package_download.html#xds110-support-utilities>

2.11 IBM PC Parallel Printer Port Based
=======================================

The two well-known "JTAG Parallel Ports" cables are the Xilinx DLC5 and
the Macraigor Wiggler.  There are many clones and variations of these on
the market.

Note that parallel ports are becoming much less common, so if you have
the choice you should probably avoid these adapters in favor of
USB-based ones.

   * Wiggler - There are many clones of this.
     Link: <http://www.macraigor.com/wiggler.htm>

   * DLC5 - From XILINX - There are many clones of this
     Link: Search the web for: "XILINX DLC5" - it is no longer produced,
     PDF schematics are easily found and it is easy to make.

   * Amontec - JTAG Accelerator
     Link: <http://www.amontec.com/jtag_accelerator.shtml>

   * Wiggler2
     Link:
     <http://www.ccac.rwth-aachen.de/~michaels/index.php/hardware/armjtag>

   * Wiggler_ntrst_inverted
     Yet another variation - See the source code, src/jtag/parport.c

   * old_amt_wiggler
     Unknown - probably not on the market today

   * arm-jtag
     Link: Most likely <http://www.olimex.com/dev/arm-jtag.html>
     [another wiggler clone]

   * chameleon
     Link: <http://www.amontec.com/chameleon.shtml>

   * Triton
     Unknown.

   * Lattice
     ispDownload from Lattice Semiconductor
     <http://www.latticesemi.com/lit/docs/devtools/dlcable.pdf>

   * flashlink
     From STMicroelectronics;
     Link:
     <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/DM00039500.pdf>

2.12 Other...
=============

   * ep93xx
     An EP93xx based Linux machine using the GPIO pins directly.

   * at91rm9200
     Like the EP93xx - but an ATMEL AT91RM9200 based solution using the
     GPIO pins on the chip.

   * bcm2835gpio
     A BCM2835-based board (e.g.  Raspberry Pi) using the GPIO pins of
     the expansion header.

   * imx_gpio
     A NXP i.MX-based board (e.g.  Wandboard) using the GPIO pins
     (should work on any i.MX processor).

   * jtag_vpi
     A JTAG driver acting as a client for the JTAG VPI server interface.

     Link: <http://github.com/fjullien/jtag_vpi>

   * vdebug
     A driver for Cadence virtual Debug Interface to emulated or
     simulated targets.  It implements a client connecting to the vdebug
     server, which in turn communicates with the emulated or simulated
     RTL model through a transactor.  The current version supports only
     JTAG as a transport, but other virtual transports, like DAP are
     planned.

   * jtag_dpi
     A JTAG driver acting as a client for the SystemVerilog Direct
     Programming Interface (DPI) for JTAG devices.  DPI allows OpenOCD
     to connect to the JTAG interface of a hardware model written in
     SystemVerilog, for example, on an emulation model of target
     hardware.

   * xlnx_pcie_xvc
     A JTAG driver exposing Xilinx Virtual Cable over PCI Express to
     OpenOCD as JTAG/SWD interface.

   * linuxgpiod
     A bitbang JTAG driver using Linux GPIO through library libgpiod.

   * sysfsgpio
     A bitbang JTAG driver using Linux legacy sysfs GPIO. This is
     deprecated from Linux v5.3; prefer using linuxgpiod.


File: openocd.info,  Node: About Jim-Tcl,  Next: Running,  Prev: Debug Adapter Hardware,  Up: Top

3 About Jim-Tcl
***************

OpenOCD uses a small "Tcl Interpreter" known as Jim-Tcl.  This
programming language provides a simple and extensible command
interpreter.

All commands presented in this Guide are extensions to Jim-Tcl.  You can
use them as simple commands, without needing to learn much of anything
about Tcl.  Alternatively, you can write Tcl programs with them.

You can learn more about Jim at its website, <http://jim.tcl.tk>.  There
is an active and responsive community, get on the mailing list if you
have any questions.  Jim-Tcl maintainers also lurk on the OpenOCD
mailing list.

   * Jim vs.  Tcl
     Jim-Tcl is a stripped down version of the well known Tcl language,
     which can be found here: <http://www.tcl.tk>.  Jim-Tcl has far
     fewer features.  Jim-Tcl is several dozens of .C files and .H files
     and implements the basic Tcl command set.  In contrast: Tcl 8.6 is
     a 4.2 MB .zip file containing 1540 files.

   * Missing Features
     Our practice has been: Add/clone the real Tcl feature if/when
     needed.  We welcome Jim-Tcl improvements, not bloat.  Also there
     are a large number of optional Jim-Tcl features that are not
     enabled in OpenOCD.

   * Scripts
     OpenOCD configuration scripts are Jim-Tcl Scripts.  OpenOCD's
     command interpreter today is a mixture of (newer) Jim-Tcl commands,
     and the (older) original command interpreter.

   * Commands
     At the OpenOCD telnet command line (or via the GDB monitor command)
     one can type a Tcl for() loop, set variables, etc.  Some of the
     commands documented in this guide are implemented as Tcl scripts,
     from a 'startup.tcl' file internal to the server.

   * Historical Note
     Jim-Tcl was introduced to OpenOCD in spring 2008.  Fall 2010,
     before OpenOCD 0.5 release, OpenOCD switched to using Jim-Tcl as a
     Git submodule, which greatly simplified upgrading Jim-Tcl to
     benefit from new features and bugfixes in Jim-Tcl.

   * Need a crash course in Tcl?
     *Note Tcl Crash Course::.


File: openocd.info,  Node: Running,  Next: OpenOCD Project Setup,  Prev: About Jim-Tcl,  Up: Top

4 Running
*********

Properly installing OpenOCD sets up your operating system to grant it
access to the debug adapters.  On Linux, this usually involves
installing a file in '/etc/udev/rules.d,' so OpenOCD has permissions.
An example rules file that works for many common adapters is shipped
with OpenOCD in the 'contrib' directory.  MS-Windows needs complex and
confusing driver configuration for every peripheral.  Such issues are
unique to each operating system, and are not detailed in this User's
Guide.

Then later you will invoke the OpenOCD server, with various options to
tell it how each debug session should work.  The '--help' option shows:
bash$ openocd --help

--help       | -h       display this help
--version    | -v       display OpenOCD version
--file       | -f       use configuration file <name>
--search     | -s       dir to search for config files and scripts
--debug      | -d       set debug level to 3
             | -d<n>    set debug level to <level>
--log_output | -l       redirect log output to file <name>
--command    | -c       run <command>

If you don't give any '-f' or '-c' options, OpenOCD tries to read the
configuration file 'openocd.cfg'.  To specify one or more different
configuration files, use '-f' options.  For example:

     openocd -f config1.cfg -f config2.cfg -f config3.cfg

Configuration files and scripts are searched for in
  1. the current directory,
  2. any search dir specified on the command line using the '-s' option,
  3. any search dir specified using the 'add_script_search_dir' command,
  4. a directory in the 'OPENOCD_SCRIPTS' environment variable (if set),
  5. '%APPDATA%/OpenOCD' (only on Windows),
  6. '$HOME/Library/Preferences/org.openocd' (only on Darwin),
  7. '$XDG_CONFIG_HOME/openocd' ('$XDG_CONFIG_HOME' defaults to
     '$HOME/.config'),
  8. '$HOME/.openocd',
  9. the site wide script library '$pkgdatadir/site' and
  10. the OpenOCD-supplied script library '$pkgdatadir/scripts'.
The first found file with a matching file name will be used.

     Note: Don't try to use configuration script names or paths which
     include the "#" character.  That character begins Tcl comments.

4.1 Simple setup, no customization
==================================

In the best case, you can use two scripts from one of the script
libraries, hook up your JTAG adapter, and start the server ...  and your
JTAG setup will just work "out of the box".  Always try to start by
reusing those scripts, but assume you'll need more customization even if
this works.  *Note OpenOCD Project Setup::.

If you find a script for your JTAG adapter, and for your board or
target, you may be able to hook up your JTAG adapter then start the
server with some variation of one of the following:

     openocd -f interface/ADAPTER.cfg -f board/MYBOARD.cfg
     openocd -f interface/ftdi/ADAPTER.cfg -f board/MYBOARD.cfg

You might also need to configure which reset signals are present, using
'-c 'reset_config trst_and_srst'' or something similar.  If all goes
well you'll see output something like

     Open On-Chip Debugger 0.4.0 (2010-01-14-15:06)
     For bug reports, read
             http://openocd.org/doc/doxygen/bugs.html
     Info : JTAG tap: lm3s.cpu tap/device found: 0x3ba00477
            (mfg: 0x23b, part: 0xba00, ver: 0x3)

Seeing that "tap/device found" message, and no warnings, means the JTAG
communication is working.  That's a key milestone, but you'll probably
need more project-specific setup.

4.2 What OpenOCD does as it starts
==================================

OpenOCD starts by processing the configuration commands provided on the
command line or, if there were no '-c command' or '-f file.cfg' options
given, in 'openocd.cfg'.  *Note Configuration Stage: configurationstage.
At the end of the configuration stage it verifies the JTAG scan chain
defined using those commands; your configuration should ensure that this
always succeeds.  Normally, OpenOCD then starts running as a server.
Alternatively, commands may be used to terminate the configuration stage
early, perform work (such as updating some flash memory), and then shut
down without acting as a server.

Once OpenOCD starts running as a server, it waits for connections from
clients (Telnet, GDB, RPC) and processes the commands issued through
those channels.

If you are having problems, you can enable internal debug messages via
the '-d' option.

Also it is possible to interleave Jim-Tcl commands w/config scripts
using the '-c' command line switch.

To enable debug output (when reporting problems or working on OpenOCD
itself), use the '-d' command line switch.  This sets the 'debug_level'
to "3", outputting the most information, including debug messages.  The
default setting is "2", outputting only informational messages, warnings
and errors.  You can also change this setting from within a telnet or
gdb session using 'debug_level<n>' (*note debug_level: debuglevel.).

You can redirect all output from the server to a file using the '-l
<logfile>' switch.

Note!  OpenOCD will launch the GDB & telnet server even if it can not
establish a connection with the target.  In general, it is possible for
the JTAG controller to be unresponsive until the target is set up
correctly via e.g.  GDB monitor commands in a GDB init script.


File: openocd.info,  Node: OpenOCD Project Setup,  Next: Config File Guidelines,  Prev: Running,  Up: Top

5 OpenOCD Project Setup
***********************

To use OpenOCD with your development projects, you need to do more than
just connect the JTAG adapter hardware (dongle) to your development
board and start the OpenOCD server.  You also need to configure your
OpenOCD server so that it knows about your adapter and board, and helps
your work.  You may also want to connect OpenOCD to GDB, possibly using
Eclipse or some other GUI.

5.1 Hooking up the JTAG Adapter
===============================

Today's most common case is a dongle with a JTAG cable on one side (such
as a ribbon cable with a 10-pin or 20-pin IDC connector) and a USB cable
on the other.  Instead of USB, some dongles use Ethernet; older ones may
use a PC parallel port, or even a serial port.

  1. _Start with power to your target board turned off_, and nothing
     connected to your JTAG adapter.  If you're particularly paranoid,
     unplug power to the board.  It's important to have the ground
     signal properly set up, unless you are using a JTAG adapter which
     provides galvanic isolation between the target board and the
     debugging host.

  2. _Be sure it's the right kind of JTAG connector._  If your dongle
     has a 20-pin ARM connector, you need some kind of adapter (or
     octopus, see below) to hook it up to boards using 14-pin or 10-pin
     connectors ...  or to 20-pin connectors which don't use ARM's
     pinout.

     In the same vein, make sure the voltage levels are compatible.  Not
     all JTAG adapters have the level shifters needed to work with 1.2
     Volt boards.

  3. _Be certain the cable is properly oriented_ or you might damage
     your board.  In most cases there are only two possible ways to
     connect the cable.  Connect the JTAG cable from your adapter to the
     board.  Be sure it's firmly connected.

     In the best case, the connector is keyed to physically prevent you
     from inserting it wrong.  This is most often done using a slot on
     the board's male connector housing, which must match a key on the
     JTAG cable's female connector.  If there's no housing, then you
     must look carefully and make sure pin 1 on the cable hooks up to
     pin 1 on the board.  Ribbon cables are frequently all grey except
     for a wire on one edge, which is red.  The red wire is pin 1.

     Sometimes dongles provide cables where one end is an "octopus" of
     color coded single-wire connectors, instead of a connector block.
     These are great when converting from one JTAG pinout to another,
     but are tedious to set up.  Use these with connector pinout
     diagrams to help you match up the adapter signals to the right
     board pins.

  4. _Connect the adapter's other end_ once the JTAG cable is connected.
     A USB, parallel, or serial port connector will go to the host which
     you are using to run OpenOCD. For Ethernet, consult the
     documentation and your network administrator.

     For USB-based JTAG adapters you have an easy sanity check at this
     point: does the host operating system see the JTAG adapter?  If
     you're running Linux, try the 'lsusb' command.  If that host is an
     MS-Windows host, you'll need to install a driver before OpenOCD
     works.

  5. _Connect the adapter's power supply, if needed._  This step is
     primarily for non-USB adapters, but sometimes USB adapters need
     extra power.

  6. _Power up the target board._  Unless you just let the magic smoke
     escape, you're now ready to set up the OpenOCD server so you can
     use JTAG to work with that board.

Talk with the OpenOCD server using telnet ('telnet localhost 4444' on
many systems) or GDB. *Note GDB and OpenOCD::.

5.2 Project Directory
=====================

There are many ways you can configure OpenOCD and start it up.

A simple way to organize them all involves keeping a single directory
for your work with a given board.  When you start OpenOCD from that
directory, it searches there first for configuration files, scripts,
files accessed through semihosting, and for code you upload to the
target board.  It is also the natural place to write files, such as log
files and data you download from the board.

5.3 Configuration Basics
========================

There are two basic ways of configuring OpenOCD, and a variety of ways
you can mix them.  Think of the difference as just being how you start
the server:

   * Many '-f file' or '-c command' options on the command line
   * No options, but a "user config file" in the current directory named
     'openocd.cfg'

Here is an example 'openocd.cfg' file for a setup using a Signalyzer
FT2232-based JTAG adapter to talk to a board with an Atmel AT91SAM7X256
microcontroller:

     source [find interface/ftdi/signalyzer.cfg]

     # GDB can also flash my flash!
     gdb_memory_map enable
     gdb_flash_program enable

     source [find target/sam7x256.cfg]

Here is the command line equivalent of that configuration:

     openocd -f interface/ftdi/signalyzer.cfg \
             -c "gdb_memory_map enable" \
             -c "gdb_flash_program enable" \
             -f target/sam7x256.cfg

You could wrap such long command lines in shell scripts, each supporting
a different development task.  One might re-flash the board with a
specific firmware version.  Another might set up a particular debugging
or run-time environment.

     Important: At this writing (October 2009) the command line method
     has problems with how it treats variables.  For example, after '-c
     "set VAR value"', or doing the same in a script, the variable VAR
     will have no value that can be tested in a later script.

Here we will focus on the simpler solution: one user config file,
including basic configuration plus any TCL procedures to simplify your
work.

5.4 User Config Files
=====================

A user configuration file ties together all the parts of a project in
one place.  One of the following will match your situation best:

   * Ideally almost everything comes from configuration files provided
     by someone else.  For example, OpenOCD distributes a 'scripts'
     directory (probably in '/usr/share/openocd/scripts' on Linux).
     Board and tool vendors can provide these too, as can individual
     user sites; the '-s' command line option lets you say where to find
     these files.  (*Note Running::.)  The AT91SAM7X256 example above
     works this way.

     Three main types of non-user configuration file each have their own
     subdirectory in the 'scripts' directory:

       1. interface - one for each different debug adapter;
       2. board - one for each different board
       3. target - the chips which integrate CPUs and other JTAG TAPs

     Best case: include just two files, and they handle everything else.
     The first is an interface config file.  The second is
     board-specific, and it sets up the JTAG TAPs and their GDB targets
     (by deferring to some 'target.cfg' file), declares all flash
     memory, and leaves you nothing to do except meet your deadline:

          source [find interface/olimex-jtag-tiny.cfg]
          source [find board/csb337.cfg]

     Boards with a single microcontroller often won't need more than the
     target config file, as in the AT91SAM7X256 example.  That's because
     there is no external memory (flash, DDR RAM), and the board
     differences are encapsulated by application code.

   * Maybe you don't know yet what your board looks like to JTAG. Once
     you know the 'interface.cfg' file to use, you may need help from
     OpenOCD to discover what's on the board.  Once you find the JTAG
     TAPs, you can just search for appropriate target and board
     configuration files ...  or write your own, from the bottom up.
     *Note Autoprobing: autoprobing.

   * You can often reuse some standard config files but need to write a
     few new ones, probably a 'board.cfg' file.  You will be using
     commands described later in this User's Guide, and working with the
     guidelines in the next chapter.

     For example, there may be configuration files for your JTAG adapter
     and target chip, but you need a new board-specific config file
     giving access to your particular flash chips.  Or you might need to
     write another target chip configuration file for a new chip built
     around the Cortex-M3 core.

          Note: When you write new configuration files, please submit
          them for inclusion in the next OpenOCD release.  For example,
          a 'board/newboard.cfg' file will help the next users of that
          board, and a 'target/newcpu.cfg' will help support users of
          any board using that chip.

   * You may need to write some C code.  It may be as simple as
     supporting a new FT2232 or parport based adapter; a bit more
     involved, like a NAND or NOR flash controller driver; or a big
     piece of work like supporting a new chip architecture.

Reuse the existing config files when you can.  Look first in the
'scripts/boards' area, then 'scripts/targets'.  You may find a board
configuration that's a good example to follow.

When you write config files, separate the reusable parts (things every
user of that interface, chip, or board needs) from ones specific to your
environment and debugging approach.

   * For example, a 'gdb-attach' event handler that invokes the 'reset
     init' command will interfere with debugging early boot code, which
     performs some of the same actions that the 'reset-init' event
     handler does.

   * Likewise, the 'arm9 vector_catch' command (or its siblings 'xscale
     vector_catch' and 'cortex_m vector_catch') can be a time-saver
     during some debug sessions, but don't make everyone use that
     either.  Keep those kinds of debugging aids in your user config
     file, along with messaging and tracing setup.  (*Note Software
     Debug Messages and Tracing: softwaredebugmessagesandtracing.)

   * You might need to override some defaults.  For example, you might
     need to move, shrink, or back up the target's work area if your
     application needs much SRAM.

   * TCP/IP port configuration is another example of something which is
     environment-specific, and should only appear in a user config file.
     *Note TCP/IP Ports: tcpipports.

5.5 Project-Specific Utilities
==============================

A few project-specific utility routines may well speed up your work.
Write them, and keep them in your project's user config file.

For example, if you are making a boot loader work on a board, it's nice
to be able to debug the "after it's loaded to RAM" parts separately from
the finicky early code which sets up the DDR RAM controller and clocks.
A script like this one, or a more GDB-aware sibling, may help:

     proc ramboot { } {
         # Reset, running the target's "reset-init" scripts
         # to initialize clocks and the DDR RAM controller.
         # Leave the CPU halted.
         reset init

         # Load CONFIG_SKIP_LOWLEVEL_INIT version into DDR RAM.
         load_image u-boot.bin 0x20000000

         # Start running.
         resume 0x20000000
     }

Then once that code is working you will need to make it boot from NOR
flash; a different utility would help.  Alternatively, some developers
write to flash using GDB. (You might use a similar script if you're
working with a flash based microcontroller application instead of a boot
loader.)

     proc newboot { } {
         # Reset, leaving the CPU halted. The "reset-init" event
         # proc gives faster access to the CPU and to NOR flash;
         # "reset halt" would be slower.
         reset init

         # Write standard version of U-Boot into the first two
         # sectors of NOR flash ... the standard version should
         # do the same lowlevel init as "reset-init".
         flash protect 0 0 1 off
         flash erase_sector 0 0 1
         flash write_bank 0 u-boot.bin 0x0
         flash protect 0 0 1 on

         # Reboot from scratch using that new boot loader.
         reset run
     }

You may need more complicated utility procedures when booting from NAND.
That often involves an extra bootloader stage, running from on-chip SRAM
to perform DDR RAM setup so it can load the main bootloader code (which
won't fit into that SRAM).

Other helper scripts might be used to write production system images,
involving considerably more than just a three stage bootloader.

5.6 Target Software Changes
===========================

Sometimes you may want to make some small changes to the software you're
developing, to help make JTAG debugging work better.  For example, in C
or assembly language code you might use '#ifdef JTAG_DEBUG' (or its
converse) around code handling issues like:

   * Watchdog Timers...  Watchdog timers are typically used to
     automatically reset systems if some application task doesn't
     periodically reset the timer.  (The assumption is that the system
     has locked up if the task can't run.)  When a JTAG debugger halts
     the system, that task won't be able to run and reset the timer ...
     potentially causing resets in the middle of your debug sessions.

     It's rarely a good idea to disable such watchdogs, since their
     usage needs to be debugged just like all other parts of your
     firmware.  That might however be your only option.

     Look instead for chip-specific ways to stop the watchdog from
     counting while the system is in a debug halt state.  It may be
     simplest to set that non-counting mode in your debugger startup
     scripts.  You may however need a different approach when, for
     example, a motor could be physically damaged by firmware remaining
     inactive in a debug halt state.  That might involve a type of
     firmware mode where that "non-counting" mode is disabled at the
     beginning then re-enabled at the end; a watchdog reset might fire
     and complicate the debug session, but hardware (or people) would be
     protected.(1)

   * ARM Semihosting...  When linked with a special runtime library
     provided with many toolchains(2), your target code can use I/O
     facilities on the debug host.  That library provides a small set of
     system calls which are handled by OpenOCD. It can let the debugger
     provide your system console and a file system, helping with early
     debugging or providing a more capable environment for
     sometimes-complex tasks like installing system firmware onto NAND
     or SPI flash.

   * ARM Wait-For-Interrupt...  Many ARM chips synchronize the JTAG
     clock using the core clock.  Low power states which stop that core
     clock thus prevent JTAG access.  Idle loops in tasking environments
     often enter those low power states via the 'WFI' instruction (or
     its coprocessor equivalent, before ARMv7).

     You may want to _disable that instruction_ in source code, or
     otherwise prevent using that state, to ensure you can get JTAG
     access at any time.(3)  For example, the OpenOCD 'halt' command may
     not work for an idle processor otherwise.

   * Delay after reset...  Not all chips have good support for debugger
     access right after reset; many LPC2xxx chips have issues here.
     Similarly, applications that reconfigure pins used for JTAG access
     as they start will also block debugger access.

     To work with boards like this, _enable a short delay loop_ the
     first thing after reset, before "real" startup activities.  For
     example, one second's delay is usually more than enough time for a
     JTAG debugger to attach, so that early code execution can be
     debugged or firmware can be replaced.

   * Debug Communications Channel (DCC)... Some processors include
     mechanisms to send messages over JTAG. Many ARM cores support
     these, as do some cores from other vendors.  (OpenOCD may be able
     to use this DCC internally, speeding up some operations like
     writing to memory.)

     Your application may want to deliver various debugging messages
     over JTAG, by _linking with a small library of code_ provided with
     OpenOCD and using the utilities there to send various kinds of
     message.  *Note Software Debug Messages and Tracing:
     softwaredebugmessagesandtracing.

5.7 Target Hardware Setup
=========================

Chip vendors often provide software development boards which are highly
configurable, so that they can support all options that product boards
may require.  _Make sure that any jumpers or switches match the system
configuration you are working with._

Common issues include:

   * JTAG setup ...  Boards may support more than one JTAG
     configuration.  Examples include jumpers controlling pullups versus
     pulldowns on the nTRST and/or nSRST signals, and choice of
     connectors (e.g.  which of two headers on the base board, or one
     from a daughtercard).  For some Texas Instruments boards, you may
     need to jumper the EMU0 and EMU1 signals (which OpenOCD won't
     currently control).

   * Boot Modes ...  Complex chips often support multiple boot modes,
     controlled by external jumpers.  Make sure this is set up
     correctly.  For example many i.MX boards from NXP need to be
     jumpered to "ATX mode" to start booting using the on-chip ROM, when
     using second stage bootloader code stored in a NAND flash chip.

     Such explicit configuration is common, and not limited to booting
     from NAND. You might also need to set jumpers to start booting
     using code loaded from an MMC/SD card; external SPI flash;
     Ethernet, UART, or USB links; NOR flash; OneNAND flash; some
     external host; or various other sources.

   * Memory Addressing ...  Boards which support multiple boot modes may
     also have jumpers to configure memory addressing.  One board, for
     example, jumpers external chipselect 0 (used for booting) to
     address either a large SRAM (which must be pre-loaded via JTAG),
     NOR flash, or NAND flash.  When it's jumpered to address NAND
     flash, that board must also be told to start booting from on-chip
     ROM.

     Your 'board.cfg' file may also need to be told this jumper
     configuration, so that it can know whether to declare NOR flash
     using 'flash bank' or instead declare NAND flash with 'nand
     device'; and likewise which probe to perform in its 'reset-init'
     handler.

     A closely related issue is bus width.  Jumpers might need to
     distinguish between 8 bit or 16 bit bus access for the flash used
     to start booting.

   * Peripheral Access ...  Development boards generally provide access
     to every peripheral on the chip, sometimes in multiple modes (such
     as by providing multiple audio codec chips).  This interacts with
     software configuration of pin multiplexing, where for example a
     given pin may be routed either to the MMC/SD controller or the GPIO
     controller.  It also often interacts with configuration jumpers.
     One jumper may be used to route signals to an MMC/SD card slot or
     an expansion bus (which might in turn affect booting); others might
     control which audio or video codecs are used.

Plus you should of course have 'reset-init' event handlers which set up
the hardware to match that jumper configuration.  That includes in
particular any oscillator or PLL used to clock the CPU, and any memory
controllers needed to access external memory and peripherals.  Without
such handlers, you won't be able to access those resources without
working target firmware which can do that setup ...  this can be awkward
when you're trying to debug that target firmware.  Even if there's a ROM
bootloader which handles a few issues, it rarely provides full access to
all board-specific capabilities.

   ---------- Footnotes ----------

   (1) Note that many systems support a "monitor mode" debug that is a
somewhat cleaner way to address such issues.  You can think of it as
only halting part of the system, maybe just one task, instead of the
whole thing.  At this writing, January 2010, OpenOCD based debugging
does not support monitor mode debug, only "halt mode" debug.

   (2) See chapter 8 "Semihosting" in ARM DUI 0203I
(http://infocenter.arm.com/help/topic/com.arm.doc.dui0203i/DUI0203I_rvct_developer_guide.pdf),
the "RealView Compilation Tools Developer Guide".  The CodeSourcery EABI
toolchain also includes a semihosting library.

   (3) As a more polite alternative, some processors have special
debug-oriented registers which can be used to change various features
including how the low power states are clocked while debugging.  The
STM32 DBGMCU_CR register is an example; at the cost of extra power
consumption, JTAG can be used during low power states.


File: openocd.info,  Node: Config File Guidelines,  Next: Server Configuration,  Prev: OpenOCD Project Setup,  Up: Top

6 Config File Guidelines
************************

This chapter is aimed at any user who needs to write a config file,
including developers and integrators of OpenOCD and any user who needs
to get a new board working smoothly.  It provides guidelines for
creating those files.

You should find the following directories under $(INSTALLDIR)/scripts,
with config files maintained upstream.  Use them as-is where you can; or
as models for new files.
   * 'interface' ...  These are for debug adapters.  Files that specify
     configuration to use specific JTAG, SWD and other adapters go here.
   * 'board' ...  Think Circuit Board, PWA, PCB, they go by many names.
     Board files contain initialization items that are specific to a
     board.

     They reuse target configuration files, since the same
     microprocessor chips are used on many boards, but support for
     external parts varies widely.  For example, the SDRAM
     initialization sequence for the board, or the type of external
     flash and what address it uses.  Any initialization sequence to
     enable that external flash or SDRAM should be found in the board
     file.  Boards may also contain multiple targets: two CPUs; or a CPU
     and an FPGA.
   * 'target' ...  Think chip.  The "target" directory represents the
     JTAG TAPs on a chip which OpenOCD should control, not a board.  Two
     common types of targets are ARM chips and FPGA or CPLD chips.  When
     a chip has multiple TAPs (maybe it has both ARM and DSP cores), the
     target config file defines all of them.
   * _more_ ...  browse for other library files which may be useful.
     For example, there are various generic and CPU-specific utilities.

The 'openocd.cfg' user config file may override features in any of the
above files by setting variables before sourcing the target file, or by
adding commands specific to their situation.

6.1 Interface Config Files
==========================

The user config file should be able to source one of these files with a
command like this:

     source [find interface/FOOBAR.cfg]

A preconfigured interface file should exist for every debug adapter in
use today with OpenOCD. That said, perhaps some of these config files
have only been used by the developer who created it.

A separate chapter gives information about how to set these up.  *Note
Debug Adapter Configuration::.  Read the OpenOCD source code (and
Developer's Guide) if you have a new kind of hardware interface and need
to provide a driver for it.

 -- Command: find 'filename'
     Prints full path to FILENAME according to OpenOCD search rules.

 -- Command: ocd_find 'filename'
     Prints full path to FILENAME according to OpenOCD search rules.
     This is a low level function used by the 'find'.  Usually you want
     to use 'find', instead.

6.2 Board Config Files
======================

The user config file should be able to source one of these files with a
command like this:

     source [find board/FOOBAR.cfg]

The point of a board config file is to package everything about a given
board that user config files need to know.  In summary the board files
should contain (if present)

  1. One or more 'source [find target/...cfg]' statements
  2. NOR flash configuration (*note NOR Configuration:
     norconfiguration.)
  3. NAND flash configuration (*note NAND Configuration:
     nandconfiguration.)
  4. Target 'reset' handlers for SDRAM and I/O configuration
  5. JTAG adapter reset configuration (*note Reset Configuration::)
  6. All things that are not "inside a chip"

Generic things inside target chips belong in target config files, not
board config files.  So for example a 'reset-init' event handler should
know board-specific oscillator and PLL parameters, which it passes to
target-specific utility code.

The most complex task of a board config file is creating such a
'reset-init' event handler.  Define those handlers last, after you
verify the rest of the board configuration works.

6.2.1 Communication Between Config files
----------------------------------------

In addition to target-specific utility code, another way that board and
target config files communicate is by following a convention on how to
use certain variables.

The full Tcl/Tk language supports "namespaces", but Jim-Tcl does not.
Thus the rule we follow in OpenOCD is this: Variables that begin with a
leading underscore are temporary in nature, and can be modified and used
at will within a target configuration file.

Complex board config files can do the things like this, for a board with
three chips:

     # Chip #1: PXA270 for network side, big endian
     set CHIPNAME network
     set ENDIAN big
     source [find target/pxa270.cfg]
     # on return: _TARGETNAME = network.cpu
     # other commands can refer to the "network.cpu" target.
     $_TARGETNAME configure .... events for this CPU..

     # Chip #2: PXA270 for video side, little endian
     set CHIPNAME video
     set ENDIAN little
     source [find target/pxa270.cfg]
     # on return: _TARGETNAME = video.cpu
     # other commands can refer to the "video.cpu" target.
     $_TARGETNAME configure .... events for this CPU..

     # Chip #3: Xilinx FPGA for glue logic
     set CHIPNAME xilinx
     unset ENDIAN
     source [find target/spartan3.cfg]

That example is oversimplified because it doesn't show any flash memory,
or the 'reset-init' event handlers to initialize external DRAM or
(assuming it needs it) load a configuration into the FPGA. Such features
are usually needed for low-level work with many boards, where "low
level" implies that the board initialization software may not be
working.  (That's a common reason to need JTAG tools.  Another is to
enable working with microcontroller-based systems, which often have no
debugging support except a JTAG connector.)

Target config files may also export utility functions to board and user
config files.  Such functions should use name prefixes, to help avoid
naming collisions.

Board files could also accept input variables from user config files.
For example, there might be a 'J4_JUMPER' setting used to identify what
kind of flash memory a development board is using, or how to set up
other clocks and peripherals.

6.2.2 Variable Naming Convention
--------------------------------

Most boards have only one instance of a chip.  However, it should be
easy to create a board with more than one such chip (as shown above).
Accordingly, we encourage these conventions for naming variables
associated with different 'target.cfg' files, to promote consistency and
so that board files can override target defaults.

Inputs to target config files include:

   * 'CHIPNAME' ...  This gives a name to the overall chip, and is used
     as part of tap identifier dotted names.  While the default is
     normally provided by the chip manufacturer, board files may need to
     distinguish between instances of a chip.
   * 'ENDIAN' ...  By default 'little' - although chips may hard-wire
     'big'.  Chips that can't change endianness don't need to use this
     variable.
   * 'CPUTAPID' ...  When OpenOCD examines the JTAG chain, it can be
     told verify the chips against the JTAG IDCODE register.  The target
     file will hold one or more defaults, but sometimes the chip in a
     board will use a different ID (perhaps a newer revision).

Outputs from target config files include:

   * '_TARGETNAME' ...  By convention, this variable is created by the
     target configuration script.  The board configuration file may make
     use of this variable to configure things like a "reset init"
     script, or other things specific to that board and that target.  If
     the chip has 2 targets, the names are '_TARGETNAME0',
     '_TARGETNAME1', ...  etc.

6.2.3 The reset-init Event Handler
----------------------------------

Board config files run in the OpenOCD configuration stage; they can't
use TAPs or targets, since they haven't been fully set up yet.  This
means you can't write memory or access chip registers; you can't even
verify that a flash chip is present.  That's done later in event
handlers, of which the target 'reset-init' handler is one of the most
important.

Except on microcontrollers, the basic job of 'reset-init' event handlers
is setting up flash and DRAM, as normally handled by boot loaders.
Microcontrollers rarely use boot loaders; they run right out of their
on-chip flash and SRAM memory.  But they may want to use one of these
handlers too, if just for developer convenience.

     Note: Because this is so very board-specific, and chip-specific, no
     examples are included here.  Instead, look at the board config
     files distributed with OpenOCD. If you have a boot loader, its
     source code will help; so will configuration files for other JTAG
     tools (*note Translating Configuration Files:
     translatingconfigurationfiles.).

Some of this code could probably be shared between different boards.
For example, setting up a DRAM controller often doesn't differ by much
except the bus width (16 bits or 32?)  and memory timings, so a reusable
TCL procedure loaded by the 'target.cfg' file might take those as
parameters.  Similarly with oscillator, PLL, and clock setup; and
disabling the watchdog.  Structure the code cleanly, and provide
comments to help the next developer doing such work.  (_You might be
that next person_ trying to reuse init code!)

The last thing normally done in a 'reset-init' handler is probing
whatever flash memory was configured.  For most chips that needs to be
done while the associated target is halted, either because JTAG memory
access uses the CPU or to prevent conflicting CPU access.

6.2.4 JTAG Clock Rate
---------------------

Before your 'reset-init' handler has set up the PLLs and clocking, you
may need to run with a low JTAG clock rate.  *Note JTAG Speed:
jtagspeed.  Then you'd increase that rate after your handler has made it
possible to use the faster JTAG clock.  When the initial low speed is
board-specific, for example because it depends on a board-specific
oscillator speed, then you should probably set it up in the board config
file; if it's target-specific, it belongs in the target config file.

For most ARM-based processors the fastest JTAG clock(1) is one sixth of
the CPU clock; or one eighth for ARM11 cores.  Consult chip
documentation to determine the peak JTAG clock rate, which might be less
than that.

     Warning: On most ARMs, JTAG clock detection is coupled to the core
     clock, so software using a 'wait for interrupt' operation blocks
     JTAG access.  Adaptive clocking provides a partial workaround, but
     a more complete solution just avoids using that instruction with
     JTAG debuggers.

If both the chip and the board support adaptive clocking, use the
'jtag_rclk' command, in case your board is used with JTAG adapter which
also supports it.  Otherwise use 'adapter speed'.  Set the slow rate at
the beginning of the reset sequence, and the faster rate as soon as the
clocks are at full speed.

6.2.5 The init_board procedure
------------------------------

The concept of 'init_board' procedure is very similar to 'init_targets'
(*Note The init_targets procedure: theinittargetsprocedure.)  - it's a
replacement of "linear" configuration scripts.  This procedure is meant
to be executed when OpenOCD enters run stage (*Note Entering the Run
Stage: enteringtherunstage,) after 'init_targets'.  The idea to have
separate 'init_targets' and 'init_board' procedures is to allow the
first one to configure everything target specific (internal flash,
internal RAM, etc.)  and the second one to configure everything board
specific (reset signals, chip frequency, reset-init event handler,
external memory, etc.).  Additionally "linear" board config file will
most likely fail when target config file uses 'init_targets' scheme
("linear" script is executed before 'init' and 'init_targets' - after),
so separating these two configuration stages is very convenient, as the
easiest way to overcome this problem is to convert board config file to
use 'init_board' procedure.  Board config scripts don't need to override
'init_targets' defined in target config files when they only need to add
some specifics.

Just as 'init_targets', the 'init_board' procedure can be overridden by
"next level" script (which sources the original), allowing greater code
reuse.

     ### board_file.cfg ###

     # source target file that does most of the config in init_targets
     source [find target/target.cfg]

     proc enable_fast_clock {} {
         # enables fast on-board clock source
         # configures the chip to use it
     }

     # initialize only board specifics - reset, clock, adapter frequency
     proc init_board {} {
         reset_config trst_and_srst trst_pulls_srst

         $_TARGETNAME configure -event reset-start {
             adapter speed 100
         }

         $_TARGETNAME configure -event reset-init {
             enable_fast_clock
             adapter speed 10000
         }
     }

6.3 Target Config Files
=======================

Board config files communicate with target config files using naming
conventions as described above, and may source one or more target config
files like this:

     source [find target/FOOBAR.cfg]

The point of a target config file is to package everything about a given
chip that board config files need to know.  In summary the target files
should contain

  1. Set defaults
  2. Add TAPs to the scan chain
  3. Add CPU targets (includes GDB support)
  4. CPU/Chip/CPU-Core specific features
  5. On-Chip flash

As a rule of thumb, a target file sets up only one chip.  For a
microcontroller, that will often include a single TAP, which is a CPU
needing a GDB target, and its on-chip flash.

More complex chips may include multiple TAPs, and the target config file
may need to define them all before OpenOCD can talk to the chip.  For
example, some phone chips have JTAG scan chains that include an ARM core
for operating system use, a DSP, another ARM core embedded in an image
processing engine, and other processing engines.

6.3.1 Default Value Boiler Plate Code
-------------------------------------

All target configuration files should start with code like this, letting
board config files express environment-specific differences in how
things should be set up.

     # Boards may override chip names, perhaps based on role,
     # but the default should match what the vendor uses
     if { [info exists CHIPNAME] } {
        set  _CHIPNAME $CHIPNAME
     } else {
        set  _CHIPNAME sam7x256
     }

     # ONLY use ENDIAN with targets that can change it.
     if { [info exists ENDIAN] } {
        set  _ENDIAN $ENDIAN
     } else {
        set  _ENDIAN little
     }

     # TAP identifiers may change as chips mature, for example with
     # new revision fields (the "3" here). Pick a good default; you
     # can pass several such identifiers to the "jtag newtap" command.
     if { [info exists CPUTAPID ] } {
        set _CPUTAPID $CPUTAPID
     } else {
        set _CPUTAPID 0x3f0f0f0f
     }

_Remember:_ Board config files may include multiple target config files,
or the same target file multiple times (changing at least 'CHIPNAME').

Likewise, the target configuration file should define '_TARGETNAME' (or
'_TARGETNAME0' etc) and use it later on when defining debug targets:

     set _TARGETNAME $_CHIPNAME.cpu
     target create $_TARGETNAME arm7tdmi -chain-position $_TARGETNAME

6.3.2 Adding TAPs to the Scan Chain
-----------------------------------

After the "defaults" are set up, add the TAPs on each chip to the JTAG
scan chain.  *Note TAP Declaration::, and the naming convention for
taps.

In the simplest case the chip has only one TAP, probably for a CPU or
FPGA. The config file for the Atmel AT91SAM7X256 looks (in part) like
this:

     jtag newtap $_CHIPNAME cpu -irlen 4 -expected-id $_CPUTAPID

A board with two such at91sam7 chips would be able to source such a
config file twice, with different values for 'CHIPNAME', so it adds a
different TAP each time.

If there are nonzero '-expected-id' values, OpenOCD attempts to verify
the actual tap id against those values.  It will issue error messages if
there is mismatch, which can help to pinpoint problems in OpenOCD
configurations.

     JTAG tap: sam7x256.cpu tap/device found: 0x3f0f0f0f
                     (Manufacturer: 0x787, Part: 0xf0f0, Version: 0x3)
     ERROR: Tap: sam7x256.cpu - Expected id: 0x12345678, Got: 0x3f0f0f0f
     ERROR: expected: mfg: 0x33c, part: 0x2345, ver: 0x1
     ERROR:      got: mfg: 0x787, part: 0xf0f0, ver: 0x3

There are more complex examples too, with chips that have multiple TAPs.
Ones worth looking at include:

   * 'target/omap3530.cfg' - with disabled ARM and DSP, plus a JRC to
     enable them
   * 'target/str912.cfg' - with flash, CPU, and boundary scan
   * 'target/ti_dm355.cfg' - with ETM, ARM, and JRC (this JRC is not
     currently used)

6.3.3 Add CPU targets
---------------------

After adding a TAP for a CPU, you should set it up so that GDB and other
commands can use it.  *Note CPU Configuration::.  For the at91sam7
example above, the command can look like this; note that '$_ENDIAN' is
not needed, since OpenOCD defaults to little endian, and this chip
doesn't support changing that.

     set _TARGETNAME $_CHIPNAME.cpu
     target create $_TARGETNAME arm7tdmi -chain-position $_TARGETNAME

Work areas are small RAM areas associated with CPU targets.  They are
used by OpenOCD to speed up downloads, and to download small snippets of
code to program flash chips.  If the chip includes a form of
"on-chip-ram" - and many do - define a work area if you can.  Again
using the at91sam7 as an example, this can look like:

     $_TARGETNAME configure -work-area-phys 0x00200000 \
                  -work-area-size 0x4000 -work-area-backup 0

6.3.4 Define CPU targets working in SMP
---------------------------------------

After setting targets, you can define a list of targets working in SMP.

     set _TARGETNAME_1 $_CHIPNAME.cpu1
     set _TARGETNAME_2 $_CHIPNAME.cpu2
     target create $_TARGETNAME_1 cortex_a -chain-position $_CHIPNAME.dap \
     -coreid 0 -dbgbase $_DAP_DBG1
     target create $_TARGETNAME_2 cortex_a -chain-position $_CHIPNAME.dap \
     -coreid 1 -dbgbase $_DAP_DBG2
     #define 2 targets working in smp.
     target smp $_CHIPNAME.cpu2 $_CHIPNAME.cpu1
In the above example on cortex_a, 2 cpus are working in SMP. In SMP only
one GDB instance is created and :
   * a set of hardware breakpoint sets the same breakpoint on all
     targets in the list.
   * halt command triggers the halt of all targets in the list.
   * resume command triggers the write context and the restart of all
     targets in the list.
   * following a breakpoint: the target stopped by the breakpoint is
     displayed to the GDB session.
   * dedicated GDB serial protocol packets are implemented for
     switching/retrieving the target displayed by the GDB session *note
     Using OpenOCD SMP with GDB: usingopenocdsmpwithgdb.

The SMP behaviour can be disabled/enabled dynamically.  On cortex_a
following command have been implemented.
   * cortex_a smp on : enable SMP mode, behaviour is as described above.
   * cortex_a smp off : disable SMP mode, the current target is the one
     displayed in the GDB session, only this target is now controlled by
     GDB session.  This behaviour is useful during system boot up.
   * cortex_a smp : display current SMP mode.
   * cortex_a smp_gdb : display/fix the core id displayed in GDB session
     see following example.

     >cortex_a smp_gdb
     gdb coreid  0 -> -1
     #0 : coreid 0 is displayed to GDB ,
     #-> -1 : next resume triggers a real resume
     > cortex_a smp_gdb 1
     gdb coreid  0 -> 1
     #0 :coreid 0 is displayed to GDB ,
     #->1  : next resume displays coreid 1 to GDB
     > resume
     > cortex_a smp_gdb
     gdb coreid  1 -> 1
     #1 :coreid 1 is displayed to GDB ,
     #->1 : next resume displays coreid 1 to GDB
     > cortex_a smp_gdb -1
     gdb coreid  1 -> -1
     #1 :coreid 1 is displayed to GDB,
     #->-1 : next resume triggers a real resume

6.3.5 Chip Reset Setup
----------------------

As a rule, you should put the 'reset_config' command into the board
file.  Most things you think you know about a chip can be tweaked by the
board.

Some chips have specific ways the TRST and SRST signals are managed.  In
the unusual case that these are _chip specific_ and can never be changed
by board wiring, they could go here.  For example, some chips can't
support JTAG debugging without both signals.

Provide a 'reset-assert' event handler if you can.  Such a handler uses
JTAG operations to reset the target, letting this target config be used
in systems which don't provide the optional SRST signal, or on systems
where you don't want to reset all targets at once.  Such a handler might
write to chip registers to force a reset, use a JRC to do that
(preferable - the target may be wedged!), or force a watchdog timer to
trigger.  (For Cortex-M targets, this is not necessary.  The target
driver knows how to use trigger an NVIC reset when SRST is not
available.)

Some chips need special attention during reset handling if they're going
to be used with JTAG. An example might be needing to send some commands
right after the target's TAP has been reset, providing a
'reset-deassert-post' event handler that writes a chip register to
report that JTAG debugging is being done.  Another would be
reconfiguring the watchdog so that it stops counting while the core is
halted in the debugger.

JTAG clocking constraints often change during reset, and in some cases
target config files (rather than board config files) are the right
places to handle some of those issues.  For example, immediately after
reset most chips run using a slower clock than they will use later.
That means that after reset (and potentially, as OpenOCD first starts
up) they must use a slower JTAG clock rate than they will use later.
*Note JTAG Speed: jtagspeed.

     Important: When you are debugging code that runs right after chip
     reset, getting these issues right is critical.  In particular, if
     you see intermittent failures when OpenOCD verifies the scan chain
     after reset, look at how you are setting up JTAG clocking.

6.3.6 The init_targets procedure
--------------------------------

Target config files can either be "linear" (script executed line-by-line
when parsed in configuration stage, *Note Configuration Stage:
configurationstage,) or they can contain a special procedure called
'init_targets', which will be executed when entering run stage (after
parsing all config files or after 'init' command, *Note Entering the Run
Stage: enteringtherunstage.)  Such procedure can be overridden by "next
level" script (which sources the original).  This concept facilitates
code reuse when basic target config files provide generic configuration
procedures and 'init_targets' procedure, which can then be sourced and
enhanced or changed in a "more specific" target config file.  This is
not possible with "linear" config scripts, because sourcing them
executes every initialization commands they provide.

     ### generic_file.cfg ###

     proc setup_my_chip {chip_name flash_size ram_size} {
         # basic initialization procedure ...
     }

     proc init_targets {} {
         # initializes generic chip with 4kB of flash and 1kB of RAM
         setup_my_chip MY_GENERIC_CHIP 4096 1024
     }

     ### specific_file.cfg ###

     source [find target/generic_file.cfg]

     proc init_targets {} {
         # initializes specific chip with 128kB of flash and 64kB of RAM
         setup_my_chip MY_CHIP_WITH_128K_FLASH_64KB_RAM 131072 65536
     }

The easiest way to convert "linear" config files to 'init_targets'
version is to enclose every line of "code" (i.e.  not 'source' commands,
procedures, etc.)  in this procedure.

For an example of this scheme see LPC2000 target config files.

The 'init_boards' procedure is a similar concept concerning board config
files (*Note The init_board procedure: theinitboardprocedure.)

6.3.7 The init_target_events procedure
--------------------------------------

A special procedure called 'init_target_events' is run just after
'init_targets' (*Note The init_targets procedure:
theinittargetsprocedure.)  and before 'init_board' (*Note The init_board
procedure: theinitboardprocedure.)  It is used to set up default target
events for the targets that do not have those events already assigned.

6.3.8 ARM Core Specific Hacks
-----------------------------

If the chip has a DCC, enable it.  If the chip is an ARM9 with some
special high speed download features - enable it.

If present, the MMU, the MPU and the CACHE should be disabled.

Some ARM cores are equipped with trace support, which permits
examination of the instruction and data bus activity.  Trace activity is
controlled through an "Embedded Trace Module" (ETM) on one of the core's
scan chains.  The ETM emits voluminous data through a "trace port".
(*Note ARM Hardware Tracing: armhardwaretracing.)  If you are using an
external trace port, configure it in your board config file.  If you are
using an on-chip "Embedded Trace Buffer" (ETB), configure it in your
target config file.

     etm config $_TARGETNAME 16 normal full etb
     etb config $_TARGETNAME $_CHIPNAME.etb

6.3.9 Internal Flash Configuration
----------------------------------

This applies ONLY TO MICROCONTROLLERS that have flash built in.

Never ever in the "target configuration file" define any type of flash
that is external to the chip.  (For example a BOOT flash on Chip Select
0.)  Such flash information goes in a board file - not the TARGET (chip)
file.

Examples:
   * at91sam7x256 - has 256K flash YES enable it.
   * str912 - has flash internal YES enable it.
   * imx27 - uses boot flash on CS0 - it goes in the board file.
   * pxa270 - again - CS0 flash - it goes in the board file.

6.4 Translating Configuration Files
===================================

If you have a configuration file for another hardware debugger or
toolset (Abatron, BDI2000, BDI3000, CCS, Lauterbach, SEGGER, Macraigor,
etc.), translating it into OpenOCD syntax is often quite
straightforward.  The most tricky part of creating a configuration
script is oftentimes the reset init sequence where e.g.  PLLs, DRAM and
the like is set up.

One trick that you can use when translating is to write small Tcl
procedures to translate the syntax into OpenOCD syntax.  This can avoid
manual translation errors and make it easier to convert other scripts
later on.

Example of transforming quirky arguments to a simple search and replace
job:

     #   Lauterbach syntax(?)
     #
     #       Data.Set c15:0x042f %long 0x40000015
     #
     #   OpenOCD syntax when using procedure below.
     #
     #       setc15 0x01 0x00050078

     proc setc15 {regs value} {
         global TARGETNAME

         echo [format "set p15 0x%04x, 0x%08x" $regs $value]

         arm mcr 15 [expr {($regs >> 12) & 0x7}] \
             [expr {($regs >> 0) & 0xf}] [expr {($regs >> 4) & 0xf}] \
             [expr {($regs >> 8) & 0x7}] $value
     }

   ---------- Footnotes ----------

   (1) A FAQ <http://www.arm.com/support/faqdev/4170.html> gives
details.


File: openocd.info,  Node: Server Configuration,  Next: Debug Adapter Configuration,  Prev: Config File Guidelines,  Up: Top

7 Server Configuration
**********************

The commands here are commonly found in the openocd.cfg file and are
used to specify what TCP/IP ports are used, and how GDB should be
supported.

7.1 Configuration Stage
=======================

When the OpenOCD server process starts up, it enters a _configuration
stage_ which is the only time that certain commands, _configuration
commands_, may be issued.  Normally, configuration commands are only
available inside startup scripts.

In this manual, the definition of a configuration command is presented
as a _Config Command_, not as a _Command_ which may be issued
interactively.  The runtime 'help' command also highlights configuration
commands, and those which may be issued at any time.

Those configuration commands include declaration of TAPs, flash banks,
the interface used for JTAG communication, and other basic setup.  The
server must leave the configuration stage before it may access or
activate TAPs.  After it leaves this stage, configuration commands may
no longer be issued.

 -- Command: command mode [command_name]
     Returns the command modes allowed by a command: 'any', 'config', or
     'exec'.  If no command is specified, returns the current command
     mode.  Returns 'unknown' if an unknown command is given.  Command
     can be multiple tokens.  (command valid any time)

     In this document, the modes are described as stages, 'config' and
     'exec' mode correspond configuration stage and run stage.  'any'
     means the command can be executed in either stages.  *Note
     Configuration Stage: configurationstage, and *Note Entering the Run
     Stage: enteringtherunstage.

7.2 Entering the Run Stage
==========================

The first thing OpenOCD does after leaving the configuration stage is to
verify that it can talk to the scan chain (list of TAPs) which has been
configured.  It will warn if it doesn't find TAPs it expects to find, or
finds TAPs that aren't supposed to be there.  You should see no errors
at this point.  If you see errors, resolve them by correcting the
commands you used to configure the server.  Common errors include using
an initial JTAG speed that's too fast, and not providing the right
IDCODE values for the TAPs on the scan chain.

Once OpenOCD has entered the run stage, a number of commands become
available.  A number of these relate to the debug targets you may have
declared.  For example, the 'mww' command will not be available until a
target has been successfully instantiated.  If you want to use those
commands, you may need to force entry to the run stage.

 -- Config Command: init
     This command terminates the configuration stage and enters the run
     stage.  This helps when you need to have the startup scripts manage
     tasks such as resetting the target, programming flash, etc.  To
     reset the CPU upon startup, add "init" and "reset" at the end of
     the config script or at the end of the OpenOCD command line using
     the '-c' command line switch.

     If this command does not appear in any startup/configuration file
     OpenOCD executes the command for you after processing all
     configuration files and/or command line options.

     NOTE: This command normally occurs near the end of your openocd.cfg
     file to force OpenOCD to "initialize" and make the targets ready.
     For example: If your openocd.cfg file needs to read/write memory on
     your target, 'init' must occur before the memory read/write
     commands.  This includes 'nand probe'.

     'init' calls the following internal OpenOCD commands to initialize
     corresponding subsystems:
      -- Config Command: target init
      -- Command: transport init
      -- Command: dap init
      -- Config Command: flash init
      -- Config Command: nand init
      -- Config Command: pld init
      -- Command: tpiu init

 -- Config Command: noinit
     Prevent OpenOCD from implicit 'init' call at the end of startup.
     Allows issuing configuration commands over telnet or Tcl
     connection.  When you are done with configuration use 'init' to
     enter the run stage.

 -- Overridable Procedure: jtag_init
     This is invoked at server startup to verify that it can talk to the
     scan chain (list of TAPs) which has been configured.

     The default implementation first tries 'jtag arp_init', which uses
     only a lightweight JTAG reset before examining the scan chain.  If
     that fails, it tries again, using a harder reset from the
     overridable procedure 'init_reset'.

     Implementations must have verified the JTAG scan chain before they
     return.  This is done by calling 'jtag arp_init' (or 'jtag
     arp_init-reset').

7.3 TCP/IP Ports
================

The OpenOCD server accepts remote commands in several syntaxes.  Each
syntax uses a different TCP/IP port, which you may specify only during
configuration (before those ports are opened).

For reasons including security, you may wish to prevent remote access
using one or more of these ports.  In such cases, just specify the
relevant port number as "disabled".  If you disable all access through
TCP/IP, you will need to use the command line '-pipe' option.

 -- Config Command: gdb_port [number]
     Normally gdb listens to a TCP/IP port, but GDB can also communicate
     via pipes(stdin/out or named pipes).  The name "gdb_port" stuck
     because it covers probably more than 90% of the normal use cases.

     No arguments reports GDB port.  "pipe" means listen to stdin output
     to stdout, an integer is base port number, "disabled" disables the
     gdb server.

     When using "pipe", also use log_output to redirect the log output
     to a file so as not to flood the stdin/out pipes.

     Any other string is interpreted as named pipe to listen to.  Output
     pipe is the same name as input pipe, but with 'o' appended, e.g.
     /var/gdb, /var/gdbo.

     The GDB port for the first target will be the base port, the second
     target will listen on gdb_port + 1, and so on.  When not specified
     during the configuration stage, the port NUMBER defaults to 3333.
     When NUMBER is not a numeric value, incrementing it to compute the
     next port number does not work.  In this case, specify the proper
     NUMBER for each target by using the option '-gdb-port' of the
     commands 'target create' or '$target_name configure'.  *Note option
     -gdb-port: gdbportoverride.

     Note: when using "gdb_port pipe", increasing the default remote
     timeout in gdb (with 'set remotetimeout') is recommended.  An
     insufficient timeout may cause initialization to fail with "Unknown
     remote qXfer reply: OK".

 -- Config Command: tcl_port [number]
     Specify or query the port used for a simplified RPC connection that
     can be used by clients to issue TCL commands and get the output
     from the Tcl engine.  Intended as a machine interface.  When not
     specified during the configuration stage, the port NUMBER defaults
     to 6666.  When specified as "disabled", this service is not
     activated.

 -- Config Command: telnet_port [number]
     Specify or query the port on which to listen for incoming telnet
     connections.  This port is intended for interaction with one human
     through TCL commands.  When not specified during the configuration
     stage, the port NUMBER defaults to 4444.  When specified as
     "disabled", this service is not activated.

7.4 GDB Configuration
=====================

You can reconfigure some GDB behaviors if needed.  The ones listed here
are static and global.  *Note Target Configuration: targetconfiguration,
about configuring individual targets.  *Note Target Events:
targetevents, about configuring target-specific event handling.

 -- Command: gdb_breakpoint_override [hard|soft|disable]
     Force breakpoint type for gdb 'break' commands.  This option
     supports GDB GUIs which don't distinguish hard versus soft
     breakpoints, if the default OpenOCD and GDB behaviour is not
     sufficient.  GDB normally uses hardware breakpoints if the memory
     map has been set up for flash regions.

 -- Config Command: gdb_flash_program (enable|disable)
     Set to 'enable' to cause OpenOCD to program the flash memory when a
     vFlash packet is received.  The default behaviour is 'enable'.

 -- Config Command: gdb_memory_map (enable|disable)
     Set to 'enable' to cause OpenOCD to send the memory configuration
     to GDB when requested.  GDB will then know when to set hardware
     breakpoints, and program flash using the GDB load command.
     'gdb_flash_program enable' must also be enabled for flash
     programming to work.  Default behaviour is 'enable'.  *Note
     gdb_flash_program: gdbflashprogram.

 -- Config Command: gdb_report_data_abort (enable|disable)
     Specifies whether data aborts cause an error to be reported by GDB
     memory read packets.  The default behaviour is 'disable'; use
     'enable' see these errors reported.

 -- Config Command: gdb_report_register_access_error (enable|disable)
     Specifies whether register accesses requested by GDB register
     read/write packets report errors or not.  The default behaviour is
     'disable'; use 'enable' see these errors reported.

 -- Config Command: gdb_target_description (enable|disable)
     Set to 'enable' to cause OpenOCD to send the target descriptions to
     gdb via qXfer:features:read packet.  The default behaviour is
     'enable'.

 -- Command: gdb_save_tdesc
     Saves the target description file to the local file system.

     The file name is target_name.xml.

7.5 Event Polling
=================

Hardware debuggers are parts of asynchronous systems, where significant
events can happen at any time.  The OpenOCD server needs to detect some
of these events, so it can report them to through TCL command line or to
GDB.

Examples of such events include:

   * One of the targets can stop running ...  maybe it triggers a code
     breakpoint or data watchpoint, or halts itself.
   * Messages may be sent over "debug message" channels ...  many
     targets support such messages sent over JTAG, for receipt by the
     person debugging or tools.
   * Loss of power ...  some adapters can detect these events.
   * Resets not issued through JTAG ...  such reset sources can include
     button presses or other system hardware, sometimes including the
     target itself (perhaps through a watchdog).
   * Debug instrumentation sometimes supports event triggering such as
     "trace buffer full" (so it can quickly be emptied) or other signals
     (to correlate with code behavior).

None of those events are signaled through standard JTAG signals.
However, most conventions for JTAG connectors include voltage level and
system reset (SRST) signal detection.  Some connectors also include
instrumentation signals, which can imply events when those signals are
inputs.

In general, OpenOCD needs to periodically check for those events, either
by looking at the status of signals on the JTAG connector or by sending
synchronous "tell me your status" JTAG requests to the various active
targets.  There is a command to manage and monitor that polling, which
is normally done in the background.

 -- Command: poll [on|off]
     Poll the current target for its current state.  (Also, *note target
     curstate: targetcurstate.)  If that target is in debug mode,
     architecture specific information about the current state is
     printed.  An optional parameter allows background polling to be
     enabled and disabled.

     You could use this from the TCL command shell, or from GDB using
     'monitor poll' command.  Leave background polling enabled while
     you're using GDB.
          > poll
          background polling: on
          target state: halted
          target halted in ARM state due to debug-request, \
                         current mode: Supervisor
          cpsr: 0x800000d3 pc: 0x11081bfc
          MMU: disabled, D-Cache: disabled, I-Cache: enabled
          >


File: openocd.info,  Node: Debug Adapter Configuration,  Next: Reset Configuration,  Prev: Server Configuration,  Up: Top

8 Debug Adapter Configuration
*****************************

Correctly installing OpenOCD includes making your operating system give
OpenOCD access to debug adapters.  Once that has been done, Tcl commands
are used to select which one is used, and to configure how it is used.

     Note: Because OpenOCD started out with a focus purely on JTAG, you
     may find places where it wrongly presumes JTAG is the only
     transport protocol in use.  Be aware that recent versions of
     OpenOCD are removing that limitation.  JTAG remains more functional
     than most other transports.  Other transports do not support
     boundary scan operations, or may be specific to a given chip
     vendor.  Some might be usable only for programming flash memory,
     instead of also for debugging.

Debug Adapters/Interfaces/Dongles are normally configured through
commands in an interface configuration file which is sourced by your
'openocd.cfg' file, or through a command line '-f interface/....cfg'
option.

     source [find interface/olimex-jtag-tiny.cfg]

These commands tell OpenOCD what type of JTAG adapter you have, and how
to talk to it.  A few cases are so simple that you only need to say what
driver to use:

     # jlink interface
     adapter driver jlink

Most adapters need a bit more configuration than that.

8.1 Adapter Configuration
=========================

The 'adapter driver' command tells OpenOCD what type of debug adapter
you are using.  Depending on the type of adapter, you may need to use
one or more additional commands to further identify or configure the
adapter.

 -- Config Command: adapter driver name
     Use the adapter driver NAME to connect to the target.

 -- Command: adapter list
     List the debug adapter drivers that have been built into the
     running copy of OpenOCD.
 -- Config Command: adapter transports transport_name+
     Specifies the transports supported by this debug adapter.  The
     adapter driver builds-in similar knowledge; use this only when
     external configuration (such as jumpering) changes what the
     hardware can support.

 -- Command: adapter name
     Returns the name of the debug adapter driver being used.

 -- Config Command: adapter usb location [<bus>-<port>[.<port>]...]
     Displays or specifies the physical USB port of the adapter to use.
     The path roots at BUS and walks down the physical ports, with each
     PORT option specifying a deeper level in the bus topology, the last
     PORT denoting where the target adapter is actually plugged.  The
     USB bus topology can be queried with the command _lsusb -t_ or
     _dmesg_.

     This command is only available if your libusb1 is at least version
     1.0.16.

 -- Config Command: adapter serial serial_string
     Specifies the SERIAL_STRING of the adapter to use.  If this command
     is not specified, serial strings are not checked.  Only the
     following adapter drivers use the serial string from this command:
     aice (aice_usb), arm-jtag-ew, cmsis_dap, ft232r, ftdi, hla (stlink,
     ti-icdi), jlink, kitprog, opendus, openjtag, osbdm, presto, rlink,
     st-link, usb_blaster (ublast2), usbprog, vsllink, xds110.

8.2 Interface Drivers
=====================

Each of the interface drivers listed here must be explicitly enabled
when OpenOCD is configured, in order to be made available at run time.

 -- Interface Driver: amt_jtagaccel
     Amontec Chameleon in its JTAG Accelerator configuration, connected
     to a PC's EPP mode parallel port.  This defines some
     driver-specific commands:

      -- Config Command: parport port number
          Specifies either the address of the I/O port (default: 0x378
          for LPT1) or the number of the '/dev/parport' device.

      -- Config Command: rtck [enable|disable]
          Displays status of RTCK option.  Optionally sets that option
          first.

 -- Interface Driver: arm-jtag-ew
     Olimex ARM-JTAG-EW USB adapter This has one driver-specific
     command:

      -- Command: armjtagew_info
          Logs some status

 -- Interface Driver: at91rm9200
     Supports bitbanged JTAG from the local system, presuming that
     system is an Atmel AT91rm9200 and a specific set of GPIOs is used.

 -- Interface Driver: cmsis-dap
     ARM CMSIS-DAP compliant based adapter v1 (USB HID based) or v2 (USB
     bulk).

      -- Config Command: cmsis_dap_vid_pid [vid pid]+
          The vendor ID and product ID of the CMSIS-DAP device.  If not
          specified the driver will attempt to auto detect the CMSIS-DAP
          device.  Currently, up to eight [VID, PID] pairs may be given,
          e.g.
               cmsis_dap_vid_pid 0xc251 0xf001 0x0d28 0x0204

      -- Config Command: cmsis_dap_backend [auto|usb_bulk|hid]
          Specifies how to communicate with the adapter:

             - 'hid' Use HID generic reports - CMSIS-DAP v1
             - 'usb_bulk' Use USB bulk - CMSIS-DAP v2
             - 'auto' First try USB bulk CMSIS-DAP v2, if not found try
               HID CMSIS-DAP v1.  This is the default if
               'cmsis_dap_backend' is not specified.

      -- Config Command: cmsis_dap_usb interface [number]
          Specifies the NUMBER of the USB interface to use in v2 mode
          (USB bulk).  In most cases need not to be specified and
          interfaces are searched by interface string or for user class
          interface.

      -- Command: cmsis-dap info
          Display various device information, like hardware version,
          firmware version, current bus status.

      -- Command: cmsis-dap cmd number number ...
          Execute an arbitrary CMSIS-DAP command.  Use for adapter
          testing or for handling of an adapter vendor specific command
          from a Tcl script.

          Take given numbers as bytes, assemble a CMSIS-DAP protocol
          command packet from them and send it to the adapter.  The
          first 4 bytes of the adapter response are logged.  See
          <https://arm-software.github.io/CMSIS_5/DAP/html/group__DAP__Commands__gr.html>

 -- Interface Driver: dummy
     A dummy software-only driver for debugging.

 -- Interface Driver: ep93xx
     Cirrus Logic EP93xx based single-board computer bit-banging (in
     development)

 -- Interface Driver: ftdi
     This driver is for adapters using the MPSSE (Multi-Protocol
     Synchronous Serial Engine) mode built into many FTDI chips, such as
     the FT2232, FT4232 and FT232H.

     The driver is using libusb-1.0 in asynchronous mode to talk to the
     FTDI device, bypassing intermediate libraries like libftdi.

     Support for new FTDI based adapters can be added completely through
     configuration files, without the need to patch and rebuild OpenOCD.

     The driver uses a signal abstraction to enable Tcl configuration
     files to define outputs for one or several FTDI GPIO. These outputs
     can then be controlled using the 'ftdi set_signal' command.
     Special signal names are reserved for nTRST, nSRST and LED (for
     blink) so that they, if defined, will be used for their customary
     purpose.  Inputs can be read using the 'ftdi get_signal' command.

     To support SWD, a signal named SWD_EN must be defined.  It is set
     to 1 when the SWD protocol is selected.  When set, the adapter
     should route the SWDIO pin to the data input.  An SWDIO_OE signal,
     if defined, will be set to 1 or 0 as required by the protocol, to
     tell the adapter to drive the data output onto the SWDIO pin or
     keep the SWDIO pin Hi-Z, respectively.

     Depending on the type of buffer attached to the FTDI GPIO, the
     outputs have to be controlled differently.  In order to support
     tristateable signals such as nSRST, both a data GPIO and an
     output-enable GPIO can be specified for each signal.  The following
     output buffer configurations are supported:

        - Push-pull with one FTDI output as (non-)inverted data line
        - Open drain with one FTDI output as (non-)inverted
          output-enable
        - Tristate with one FTDI output as (non-)inverted data line and
          another FTDI output as (non-)inverted output-enable
        - Unbuffered, using the FTDI GPIO as a tristate output directly
          by switching data and direction as necessary

     These interfaces have several commands, used to configure the
     driver before initializing the JTAG scan chain:

      -- Config Command: ftdi vid_pid [vid pid]+
          The vendor ID and product ID of the adapter.  Up to eight
          [VID, PID] pairs may be given, e.g.
               ftdi vid_pid 0x0403 0xcff8 0x15ba 0x0003

      -- Config Command: ftdi device_desc description
          Provides the USB device description (the _iProduct string_) of
          the adapter.  If not specified, the device description is
          ignored during device selection.

      -- Config Command: ftdi channel channel
          Selects the channel of the FTDI device to use for MPSSE
          operations.  Most adapters use the default, channel 0, but
          there are exceptions.

      -- Config Command: ftdi layout_init data direction
          Specifies the initial values of the FTDI GPIO data and
          direction registers.  Each value is a 16-bit number
          corresponding to the concatenation of the high and low FTDI
          GPIO registers.  The values should be selected based on the
          schematics of the adapter, such that all signals are set to
          safe levels with minimal impact on the target system.  Avoid
          floating inputs, conflicting outputs and initially asserted
          reset signals.

      -- Command: ftdi layout_signal name [-data|-ndata data_mask]
               [-input|-ninput input_mask] [-oe|-noe oe_mask]
               [-alias|-nalias name]
          Creates a signal with the specified NAME, controlled by one or
          more FTDI GPIO pins via a range of possible buffer
          connections.  The masks are FTDI GPIO register bitmasks to
          tell the driver the connection and type of the output buffer
          driving the respective signal.  DATA_MASK is the bitmask for
          the pin(s) connected to the data input of the output buffer.
          '-ndata' is used with inverting data inputs and '-data' with
          non-inverting inputs.  The '-oe' (or '-noe') option tells
          where the output-enable (or not-output-enable) input to the
          output buffer is connected.  The options '-input' and
          '-ninput' specify the bitmask for pins to be read with the
          method 'ftdi get_signal'.

          Both DATA_MASK and OE_MASK need not be specified.  For
          example, a simple open-collector transistor driver would be
          specified with '-oe' only.  In that case the signal can only
          be set to drive low or to Hi-Z and the driver will complain if
          the signal is set to drive high.  Which means that if it's a
          reset signal, 'reset_config' must be specified as
          'srst_open_drain', not 'srst_push_pull'.

          A special case is provided when '-data' and '-oe' is set to
          the same bitmask.  Then the FTDI pin is considered being
          connected straight to the target without any buffer.  The FTDI
          pin is then switched between output and input as necessary to
          provide the full set of low, high and Hi-Z characteristics.
          In all other cases, the pins specified in a signal definition
          are always driven by the FTDI.

          If '-alias' or '-nalias' is used, the signal is created
          identical (or with data inverted) to an already specified
          signal NAME.

      -- Command: ftdi set_signal name 0|1|z
          Set a previously defined signal to the specified level.
             - '0', drive low
             - '1', drive high
             - 'z', set to high-impedance

      -- Command: ftdi get_signal name
          Get the value of a previously defined signal.

      -- Command: ftdi tdo_sample_edge rising|falling
          Configure TCK edge at which the adapter samples the value of
          the TDO signal

          Due to signal propagation delays, sampling TDO on rising TCK
          can become quite peculiar at high JTAG clock speeds.  However,
          FTDI chips offer a possibility to sample TDO on falling edge
          of TCK. With some board/adapter configurations, this may
          increase stability at higher JTAG clocks.
             - 'rising', sample TDO on rising edge of TCK - this is the
               default
             - 'falling', sample TDO on falling edge of TCK

     For example adapter definitions, see the configuration files
     shipped in the 'interface/ftdi' directory.

 -- Interface Driver: ft232r
     This driver is implementing synchronous bitbang mode of an FTDI
     FT232R, FT230X, FT231X and similar USB UART bridge ICs by reusing
     RS232 signals as GPIO. It currently doesn't support using CBUS pins
     as GPIO.

     List of connections (default physical pin numbers for FT232R in
     28-pin SSOP package):
        - RXD(5) - TDI
        - TXD(1) - TCK
        - RTS(3) - TDO
        - CTS(11) - TMS
        - DTR(2) - TRST
        - DCD(10) - SRST

     User can change default pinout by supplying configuration commands
     with GPIO numbers or RS232 signal names.  GPIO numbers correspond
     to bit numbers in FTDI GPIO register.  They differ from physical
     pin numbers.  For details see actual FTDI chip datasheets.  Every
     JTAG line must be configured to unique GPIO number different than
     any other JTAG line, even those lines that are sometimes not used
     like TRST or SRST.

     FT232R
        - bit 7 - RI
        - bit 6 - DCD
        - bit 5 - DSR
        - bit 4 - DTR
        - bit 3 - CTS
        - bit 2 - RTS
        - bit 1 - RXD
        - bit 0 - TXD

     These interfaces have several commands, used to configure the
     driver before initializing the JTAG scan chain:

      -- Config Command: ft232r vid_pid VID PID
          The vendor ID and product ID of the adapter.  If not
          specified, default 0x0403:0x6001 is used.

      -- Config Command: ft232r jtag_nums TCK TMS TDI TDO
          Set four JTAG GPIO numbers at once.  If not specified, default
          0 3 1 2 or TXD CTS RXD RTS is used.

      -- Config Command: ft232r tck_num TCK
          Set TCK GPIO number.  If not specified, default 0 or TXD is
          used.

      -- Config Command: ft232r tms_num TMS
          Set TMS GPIO number.  If not specified, default 3 or CTS is
          used.

      -- Config Command: ft232r tdi_num TDI
          Set TDI GPIO number.  If not specified, default 1 or RXD is
          used.

      -- Config Command: ft232r tdo_num TDO
          Set TDO GPIO number.  If not specified, default 2 or RTS is
          used.

      -- Config Command: ft232r trst_num TRST
          Set TRST GPIO number.  If not specified, default 4 or DTR is
          used.

      -- Config Command: ft232r srst_num SRST
          Set SRST GPIO number.  If not specified, default 6 or DCD is
          used.

      -- Config Command: ft232r restore_serial WORD
          Restore serial port after JTAG. This USB bitmode control word
          (16-bit) will be sent before quit.  Lower byte should set GPIO
          direction register to a "sane" state: 0x15 for TXD RTS DTR as
          outputs (1), others as inputs (0).  Higher byte is usually 0
          to disable bitbang mode.  When kernel driver reattaches,
          serial port should continue to work.  Value 0xFFFF disables
          sending control word and serial port, then kernel driver will
          not reattach.  If not specified, default 0xFFFF is used.

 -- Interface Driver: remote_bitbang
     Drive JTAG from a remote process.  This sets up a UNIX or TCP
     socket connection with a remote process and sends ASCII encoded
     bitbang requests to that process instead of directly driving JTAG.

     The remote_bitbang driver is useful for debugging software running
     on processors which are being simulated.

      -- Config Command: remote_bitbang port number
          Specifies the TCP port of the remote process to connect to or
          0 to use UNIX sockets instead of TCP.

      -- Config Command: remote_bitbang host hostname
          Specifies the hostname of the remote process to connect to
          using TCP, or the name of the UNIX socket to use if
          remote_bitbang port is 0.

     For example, to connect remotely via TCP to the host foobar you
     might have something like:

          adapter driver remote_bitbang
          remote_bitbang port 3335
          remote_bitbang host foobar

     To connect to another process running locally via UNIX sockets with
     socket named mysocket:

          adapter driver remote_bitbang
          remote_bitbang port 0
          remote_bitbang host mysocket

 -- Interface Driver: usb_blaster
     USB JTAG/USB-Blaster compatibles over one of the userspace
     libraries for FTDI chips.  These interfaces have several commands,
     used to configure the driver before initializing the JTAG scan
     chain:

      -- Config Command: usb_blaster vid_pid vid pid
          The vendor ID and product ID of the FTDI FT245 device.  If not
          specified, default values are used.  Currently, only one VID,
          PID pair may be given, e.g.  for Altera USB-Blaster (default):
               usb_blaster vid_pid 0x09FB 0x6001
          The following VID/PID is for Kolja Waschk's USB JTAG:
               usb_blaster vid_pid 0x16C0 0x06AD

      -- Command: usb_blaster pin (pin6|pin8) (0|1|s|t)
          Sets the state or function of the unused GPIO pins on
          USB-Blasters (pins 6 and 8 on the female JTAG header).  These
          pins can be used as SRST and/or TRST provided the appropriate
          connections are made on the target board.

          For example, to use pin 6 as SRST:
               usb_blaster pin pin6 s
               reset_config srst_only

      -- Config Command: usb_blaster lowlevel_driver (ftdi|ublast2)
          Chooses the low level access method for the adapter.  If not
          specified, 'ftdi' is selected unless it wasn't enabled during
          the configure stage.  USB-Blaster II needs 'ublast2'.

      -- Config Command: usb_blaster firmware PATH
          This command specifies PATH to access USB-Blaster II firmware
          image.  To be used with USB-Blaster II only.

 -- Interface Driver: gw16012
     Gateworks GW16012 JTAG programmer.  This has one driver-specific
     command:

      -- Config Command: parport port [port_number]
          Display either the address of the I/O port (default: 0x378 for
          LPT1) or the number of the '/dev/parport' device.  If a
          parameter is provided, first switch to use that port.  This is
          a write-once setting.

 -- Interface Driver: jlink
     SEGGER J-Link family of USB adapters.  It currently supports JTAG
     and SWD transports.

          Compatibility Note: SEGGER released many firmware versions for
          the many hardware versions they produced.  OpenOCD was
          extensively tested and intended to run on all of them, but
          some combinations were reported as incompatible.  As a general
          recommendation, it is advisable to use the latest firmware
          version available for each hardware version.  However the
          current V8 is a moving target, and SEGGER firmware versions
          released after the OpenOCD was released may not be compatible.
          In such cases it is recommended to revert to the last known
          functional version.  For 0.5.0, this is from "Feb 8 2012
          14:30:39", packed with 4.42c.  For 0.6.0, the last known
          version is from "May 3 2012 18:36:22", packed with 4.46f.

      -- Command: jlink hwstatus
          Display various hardware related information, for example
          target voltage and pin states.
      -- Command: jlink freemem
          Display free device internal memory.
      -- Command: jlink jtag [2|3]
          Set the JTAG command version to be used.  Without argument,
          show the actual JTAG command version.
      -- Command: jlink config
          Display the device configuration.
      -- Command: jlink config targetpower [on|off]
          Set the target power state on JTAG-pin 19.  Without argument,
          show the target power state.
      -- Command: jlink config mac [ff:ff:ff:ff:ff:ff]
          Set the MAC address of the device.  Without argument, show the
          MAC address.
      -- Command: jlink config ip [A.B.C.D(/E|F.G.H.I)]
          Set the IP configuration of the device, where A.B.C.D is the
          IP address, E the bit of the subnet mask and F.G.H.I the
          subnet mask.  Without arguments, show the IP configuration.
      -- Command: jlink config usb [0 to 3]
          Set the USB address of the device.  This will also change the
          USB Product ID (PID) of the device.  Without argument, show
          the USB address.
      -- Command: jlink config reset
          Reset the current configuration.
      -- Command: jlink config write
          Write the current configuration to the internal persistent
          storage.
      -- Command: jlink emucom write <channel> <data>
          Write data to an EMUCOM channel.  The data needs to be encoded
          as hexadecimal pairs.

          The following example shows how to write the three bytes 0xaa,
          0x0b and 0x23 to the EMUCOM channel 0x10:
               > jlink emucom write 0x10 aa0b23
      -- Command: jlink emucom read <channel> <length>
          Read data from an EMUCOM channel.  The read data is encoded as
          hexadecimal pairs.

          The following example shows how to read 4 bytes from the
          EMUCOM channel 0x0:
               > jlink emucom read 0x0 4
               77a90000
      -- Config Command: jlink usb <0 to 3>
          Set the USB address of the interface, in case more than one
          adapter is connected to the host.  If not specified, USB
          addresses are not considered.  Device selection via USB
          address is not always unambiguous.  It is recommended to use
          the serial number instead, if possible.

          As a configuration command, it can be used only before 'init'.

 -- Interface Driver: kitprog
     This driver is for Cypress Semiconductor's KitProg adapters.  The
     KitProg is an SWD-only adapter that is designed to be used with
     Cypress's PSoC and PRoC device families, but it is possible to use
     it with some other devices.  If you are using this adapter with a
     PSoC or a PRoC, you may need to add 'kitprog_init_acquire_psoc' or
     'kitprog acquire_psoc' to your configuration script.

     Note that this driver is for the proprietary KitProg protocol, not
     the CMSIS-DAP mode introduced in firmware 2.14.  If the KitProg is
     in CMSIS-DAP mode, it cannot be used with this driver, and must
     either be used with the cmsis-dap driver or switched back to
     KitProg mode.  See the Cypress KitProg User Guide for instructions
     on how to switch KitProg modes.

     Known limitations:
        * The frequency of SWCLK cannot be configured, and varies
          between 1.6 MHz and 2.7 MHz.
        * For firmware versions below 2.14, "JTAG to SWD" sequences are
          replaced by "SWD line reset" in the driver.  This is for two
          reasons.  First, the KitProg does not support sending
          arbitrary SWD sequences, and only firmware 2.14 and later
          implement both "JTAG to SWD" and "SWD line reset" in firmware.
          Earlier firmware versions only implement "SWD line reset".
          Second, due to a firmware quirk, an SWD sequence must be sent
          after every target reset in order to re-establish
          communications with the target.
        * Due in part to the limitation above, KitProg devices with
          firmware below version 2.14 will need to use
          'kitprog_init_acquire_psoc' in order to communicate with PSoC
          5LP devices.  This is because, assuming debug is not disabled
          on the PSoC, the PSoC 5LP needs its JTAG interface switched to
          SWD mode before communication can begin, but prior to firmware
          2.14, "JTAG to SWD" could only be sent with an acquisition
          sequence.

      -- Config Command: kitprog_init_acquire_psoc
          Indicate that a PSoC acquisition sequence needs to be run
          during adapter init.  Please be aware that the acquisition
          sequence hard-resets the target.

      -- Command: kitprog acquire_psoc
          Run a PSoC acquisition sequence immediately.  Typically, this
          should not be used outside of the target-specific
          configuration scripts since it hard-resets the target as a
          side-effect.  This is necessary for "reset halt" on some PSoC
          4 series devices.

      -- Command: kitprog info
          Display various adapter information, such as the hardware
          version, firmware version, and target voltage.

 -- Interface Driver: parport
     Supports PC parallel port bit-banging cables: Wigglers, PLD
     download cable, and more.  These interfaces have several commands,
     used to configure the driver before initializing the JTAG scan
     chain:

      -- Config Command: parport cable name
          Set the layout of the parallel port cable used to connect to
          the target.  This is a write-once setting.  Currently valid
          cable NAME values include:

             - altium Altium Universal JTAG cable.
             - arm-jtag Same as original wiggler except SRST and TRST
               connections reversed and TRST is also inverted.
             - chameleon The Amontec Chameleon's CPLD when operated in
               configuration mode.  This is only used to program the
               Chameleon itself, not a connected target.
             - dlc5 The Xilinx Parallel cable III.
             - flashlink The ST Parallel cable.
             - lattice Lattice ispDOWNLOAD Cable
             - old_amt_wiggler The Wiggler configuration that comes with
               some versions of Amontec's Chameleon Programmer.  The new
               version available from the website uses the original
               Wiggler layout ('WIGGLER')
             - triton The parallel port adapter found on the "Karo
               Triton 1 Development Board".  This is also the layout
               used by the HollyGates design (see
               <http://www.lartmaker.nl/projects/jtag/>).
             - wiggler The original Wiggler layout, also supported by
               several clones, such as the Olimex ARM-JTAG
             - wiggler2 Same as original wiggler except an led is fitted
               on D5.
             - wiggler_ntrst_inverted Same as original wiggler except
               TRST is inverted.

      -- Config Command: parport port [port_number]
          Display either the address of the I/O port (default: 0x378 for
          LPT1) or the number of the '/dev/parport' device.  If a
          parameter is provided, first switch to use that port.  This is
          a write-once setting.

          When using PPDEV to access the parallel port, use the number
          of the parallel port: 'parport port 0' (the default).  If
          'parport port 0x378' is specified you may encounter a problem.

      -- Config Command: parport toggling_time [nanoseconds]
          Displays how many nanoseconds the hardware needs to toggle
          TCK; the parport driver uses this value to obey the 'adapter
          speed' configuration.  When the optional NANOSECONDS parameter
          is given, that setting is changed before displaying the
          current value.

          The default setting should work reasonably well on commodity
          PC hardware.  However, you may want to calibrate for your
          specific hardware.
               Tip: To measure the toggling time with a logic analyzer
               or a digital storage oscilloscope, follow the procedure
               below:
                    > parport toggling_time 1000
                    > adapter speed 500
               This sets the maximum JTAG clock speed of the hardware,
               but the actual speed probably deviates from the requested
               500 kHz.  Now, measure the time between the two closest
               spaced TCK transitions.  You can use 'runtest 1000' or
               something similar to generate a large set of samples.
               Update the setting to match your measurement:
                    > parport toggling_time <measured nanoseconds>
               Now the clock speed will be a better match for 'adapter
               speed' command given in OpenOCD scripts and event
               handlers.

               You can do something similar with many digital
               multimeters, but note that you'll probably need to run
               the clock continuously for several seconds before it
               decides what clock rate to show.  Adjust the toggling
               time up or down until the measured clock rate is a good
               match with the rate you specified in the 'adapter speed'
               command; be conservative.

      -- Config Command: parport write_on_exit (on|off)
          This will configure the parallel driver to write a known
          cable-specific value to the parallel interface on exiting
          OpenOCD.

     For example, the interface configuration file for a classic
     "Wiggler" cable on LPT2 might look something like this:

          adapter driver parport
          parport port 0x278
          parport cable wiggler

 -- Interface Driver: presto
     ASIX PRESTO USB JTAG programmer.

 -- Interface Driver: rlink
     Raisonance RLink USB adapter

 -- Interface Driver: usbprog
     usbprog is a freely programmable USB adapter.

 -- Interface Driver: vsllink
     vsllink is part of Versaloon which is a versatile USB programmer.

          Note: This defines quite a few driver-specific commands, which
          are not currently documented here.

 -- Interface Driver: hla
     This is a driver that supports multiple High Level Adapters.  This
     type of adapter does not expose some of the lower level api's that
     OpenOCD would normally use to access the target.

     Currently supported adapters include the STMicroelectronics
     ST-LINK, TI ICDI and Nuvoton Nu-Link.  ST-LINK firmware version >=
     V2.J21.S4 recommended due to issues with earlier versions of
     firmware where serial number is reset after first use.  Suggest
     using ST firmware update utility to upgrade ST-LINK firmware even
     if current version reported is V2.J21.S4.

      -- Config Command: hla_device_desc description
          Currently Not Supported.

      -- Config Command: hla_layout (stlink|icdi|nulink)
          Specifies the adapter layout to use.

      -- Config Command: hla_vid_pid [vid pid]+
          Pairs of vendor IDs and product IDs of the device.

      -- Config Command: hla_stlink_backend (usb | tcp [port])
          _ST-Link only:_ Choose between 'exclusive' USB communication
          (the default backend) or 'shared' mode using ST-Link TCP
          server (the default port is 7184).

          _Note:_ ST-Link TCP server is a binary application provided by
          ST available from ST-LINK server software module
          (https://www.st.com/en/development-tools/st-link-server.html).

      -- Command: hla_command command
          Execute a custom adapter-specific command.  The COMMAND string
          is passed as is to the underlying adapter layout handler.

 -- Interface Driver: st-link
     This is a driver that supports STMicroelectronics adapters
     ST-LINK/V2 (from firmware V2J24) and STLINK-V3, thanks to a new API
     that provides directly access the arm ADIv5 DAP.

     The new API provide access to multiple AP on the same DAP, but the
     maximum number of the AP port is limited by the specific firmware
     version (e.g.  firmware V2J29 has 3 as maximum AP number, while
     V2J32 has 8).  An error is returned for any AP number above the
     maximum allowed value.

     _Note:_ Either these same adapters and their older versions are
     also supported by *note the hla interface driver: hla_interface.

      -- Config Command: st-link backend (usb | tcp [port])
          Choose between 'exclusive' USB communication (the default
          backend) or 'shared' mode using ST-Link TCP server (the
          default port is 7184).

          _Note:_ ST-Link TCP server is a binary application provided by
          ST available from ST-LINK server software module
          (https://www.st.com/en/development-tools/st-link-server.html).

          _Note:_ ST-Link TCP server does not support the SWIM
          transport.

      -- Config Command: st-link vid_pid [vid pid]+
          Pairs of vendor IDs and product IDs of the device.

      -- Command: st-link cmd rx_n (tx_byte)+
          Sends an arbitrary command composed by the sequence of bytes
          TX_BYTE and receives RX_N bytes.

          For example, the command to read the target's supply voltage
          is one byte 0xf7 followed by 15 bytes zero.  It returns 8
          bytes, where the first 4 bytes represent the ADC sampling of
          the reference voltage 1.2V and the last 4 bytes represent the
          ADC sampling of half the target's supply voltage.
               > st-link cmd 8 0xf7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
               0xf1 0x05 0x00 0x00 0x0b 0x08 0x00 0x00
          The result can be converted to Volts (ignoring the most
          significant bytes, always zero)
               > set a [st-link cmd 8 0xf7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
               > set n [expr {[lindex $a 4] + 256 * [lindex $a 5]}]
               > set d [expr {[lindex $a 0] + 256 * [lindex $a 1]}]
               > echo [expr {2 * 1.2 * $n / $d}]
               3.24891518738

 -- Interface Driver: opendous
     opendous-jtag is a freely programmable USB adapter.

 -- Interface Driver: ulink
     This is the Keil ULINK v1 JTAG debugger.

 -- Interface Driver: xds110
     The XDS110 is included as the embedded debug probe on many Texas
     Instruments LaunchPad evaluation boards.  The XDS110 is also
     available as a stand-alone USB debug probe with the added
     capability to supply power to the target board.  The following
     commands are supported by the XDS110 driver:

      -- Config Command: xds110 supply voltage_in_millivolts
          Available only on the XDS110 stand-alone probe.  Sets the
          voltage level of the XDS110 power supply.  A value of 0 leaves
          the supply off.  Otherwise, the supply can be set to any value
          in the range 1800 to 3600 millivolts.

      -- Command: xds110 info
          Displays information about the connected XDS110 debug probe
          (e.g.  firmware version).

 -- Interface Driver: xlnx_pcie_xvc
     This driver supports the Xilinx Virtual Cable (XVC) over PCI
     Express.  It is commonly found in Xilinx based PCI Express designs.
     It allows debugging fabric based JTAG/SWD devices such as
     Cortex-M1/M3 microcontrollers.  Access to this is exposed via
     extended capability registers in the PCI Express configuration
     space.

     For more information see Xilinx PG245 (Section on From_PCIE_to_JTAG
     mode).

      -- Config Command: xlnx_pcie_xvc config device
          Specifies the PCI Express device via parameter DEVICE to use.

          The correct value for DEVICE can be obtained by looking at the
          output of lscpi -D (first column) for the corresponding
          device.

          The string will be of the format "DDDD:BB:SS.F" such as
          "0000:65:00.1".

 -- Interface Driver: bcm2835gpio
     This SoC is present in Raspberry Pi which is a cheap single-board
     computer exposing some GPIOs on its expansion header.

     The driver accesses memory-mapped GPIO peripheral registers
     directly for maximum performance, but the only possible race
     condition is for the pins' modes/muxing (which is highly unlikely),
     so it should be able to coexist nicely with both sysfs bitbanging
     and various peripherals' kernel drivers.  The driver restores the
     previous configuration on exit.

     GPIO numbers >= 32 can't be used for performance reasons.

     See 'interface/raspberrypi-native.cfg' for a sample config and
     pinout.

      -- Config Command: bcm2835gpio jtag_nums TCK TMS TDI TDO
          Set JTAG transport GPIO numbers for TCK, TMS, TDI, and TDO (in
          that order).  Must be specified to enable JTAG transport.
          These pins can also be specified individually.

      -- Config Command: bcm2835gpio tck_num TCK
          Set TCK GPIO number.  Must be specified to enable JTAG
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio jtag_nums'.

      -- Config Command: bcm2835gpio tms_num TMS
          Set TMS GPIO number.  Must be specified to enable JTAG
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio jtag_nums'.

      -- Config Command: bcm2835gpio tdo_num TDO
          Set TDO GPIO number.  Must be specified to enable JTAG
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio jtag_nums'.

      -- Config Command: bcm2835gpio tdi_num TDI
          Set TDI GPIO number.  Must be specified to enable JTAG
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio jtag_nums'.

      -- Config Command: bcm2835gpio swd_nums SWCLK SWDIO
          Set SWD transport GPIO numbers for SWCLK and SWDIO (in that
          order).  Must be specified to enable SWD transport.  These
          pins can also be specified individually.

      -- Config Command: bcm2835gpio swclk_num SWCLK
          Set SWCLK GPIO number.  Must be specified to enable SWD
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio swd_nums'.

      -- Config Command: bcm2835gpio swdio_num SWDIO
          Set SWDIO GPIO number.  Must be specified to enable SWD
          transport.  Can also be specified using the configuration
          command 'bcm2835gpio swd_nums'.

      -- Config Command: bcm2835gpio swdio_dir_num SWDIO DIR
          Set SWDIO direction control pin GPIO number.  If specified,
          this pin can be used to control the direction of an external
          buffer on the SWDIO pin (set=output mode, clear=input mode).
          If not specified, this feature is disabled.

      -- Config Command: bcm2835gpio srst_num SRST
          Set SRST GPIO number.  Must be specified to enable SRST.

      -- Config Command: bcm2835gpio trst_num TRST
          Set TRST GPIO number.  Must be specified to enable TRST.

      -- Config Command: bcm2835gpio speed_coeffs SPEED_COEFF
               SPEED_OFFSET
          Set SPEED_COEFF and SPEED_OFFSET for delay calculations.  If
          unspecified, speed_coeff defaults to 113714, and speed_offset
          defaults to 28.

      -- Config Command: bcm2835gpio peripheral_base BASE
          Set the peripheral base register address to access GPIOs.  For
          the RPi1, use 0x20000000.  For RPi2 and RPi3, use 0x3F000000.
          For RPi4, use 0xFE000000.  A full list can be found in the
          official guide
          (https://www.raspberrypi.org/documentation/hardware/raspberrypi/peripheral_addresses.md).

 -- Interface Driver: imx_gpio
     i.MX SoC is present in many community boards.  Wandboard is an
     example of the one which is most popular.

     This driver is mostly the same as bcm2835gpio.

     See 'interface/imx-native.cfg' for a sample config and pinout.

 -- Interface Driver: linuxgpiod
     Linux provides userspace access to GPIO through libgpiod since
     Linux kernel version v4.6.  The driver emulates either JTAG and SWD
     transport through bitbanging.

     See 'interface/dln-2-gpiod.cfg' for a sample config.

 -- Interface Driver: sysfsgpio
     Linux legacy userspace access to GPIO through sysfs is deprecated
     from Linux kernel version v5.3.  Prefer using linuxgpiod, instead.

     See 'interface/sysfsgpio-raspberrypi.cfg' for a sample config.

 -- Interface Driver: openjtag
     OpenJTAG compatible USB adapter.  This defines some driver-specific
     commands:

      -- Config Command: openjtag variant variant
          Specifies the variant of the OpenJTAG adapter (see
          <http://www.openjtag.org/>).  Currently valid VARIANT values
          include:

             - standard Standard variant (default).
             - cy7c65215 Cypress CY7C65215 Dual Channel USB-Serial
               Bridge Controller (see
               <http://www.cypress.com/?rID=82870>).

      -- Config Command: openjtag device_desc string
          The USB device description string of the adapter.  This value
          is only used with the standard variant.

 -- Interface Driver: vdebug
     Cadence Virtual Debug Interface driver.

      -- Config Command: vdebug server host:port
          Specifies the host and TCP port number where the vdebug server
          runs.

      -- Config Command: vdebug batching value
          Specifies the batching method for the vdebug request.
          Possible values are 0 for no batching 1 or wr to batch write
          transactions together (default) 2 or rw to batch both read and
          write transactions

      -- Config Command: vdebug polling min max
          Takes two values, representing the polling interval in ms.
          Lower values mean faster debugger responsiveness, but lower
          emulation performance.  The minimum should be around 10,
          maximum should not exceed 1000, which is the default gdb and
          keepalive timeout value.

      -- Config Command: vdebug bfm_path path clk_period
          Specifies the hierarchical path and input clk period of the
          vdebug BFM in the design.  The hierarchical path uses Verilog
          notation top.inst.inst The clock period must include the unit,
          for instance 40ns.

      -- Config Command: vdebug mem_path path base size
          Specifies the hierarchical path to the design memory instance
          for backdoor access.  Up to 4 memories can be specified.  The
          hierarchical path uses Verilog notation.  The base specifies
          start address in the design address space, size its size in
          bytes.  Both values can use hexadecimal notation with prefix
          0x.

 -- Interface Driver: jtag_dpi
     SystemVerilog Direct Programming Interface (DPI) compatible driver
     for JTAG devices in emulation.  The driver acts as a client for the
     SystemVerilog DPI server interface.

      -- Config Command: jtag_dpi set_port port
          Specifies the TCP/IP port number of the SystemVerilog DPI
          server interface.

      -- Config Command: jtag_dpi set_address address
          Specifies the TCP/IP address of the SystemVerilog DPI server
          interface.

 -- Interface Driver: buspirate

     This driver is for the Bus Pirate (see
     <http://dangerousprototypes.com/docs/Bus_Pirate>) and compatible
     devices.  It uses a simple data protocol over a serial port
     connection.

     Most hardware development boards have a UART, a real serial port,
     or a virtual USB serial device, so this driver allows you to start
     building your own JTAG adapter without the complexity of a custom
     USB connection.

      -- Config Command: buspirate port serial_port
          Specify the serial port's filename.  For example:
               buspirate port /dev/ttyUSB0

      -- Config Command: buspirate speed (normal|fast)
          Set the communication speed to 115k (normal) or 1M (fast).
          For example:
               buspirate speed normal

      -- Config Command: buspirate mode (normal|open-drain)
          Set the Bus Pirate output mode.
             - In normal mode (push/pull), do not enable the pull-ups,
               and do not connect I/O header pin VPU to JTAG VREF.
             - In open drain mode, you will then need to enable the
               pull-ups.
          For example:
               buspirate mode normal

      -- Config Command: buspirate pullup (0|1)
          Whether to connect (1) or not (0) the I/O header pin VPU (JTAG
          VREF) to the pull-up/pull-down resistors on MOSI (JTAG TDI),
          CLK (JTAG TCK), MISO (JTAG TDO) and CS (JTAG TMS). For
          example:
               buspirate pullup 0

      -- Config Command: buspirate vreg (0|1)
          Whether to enable (1) or disable (0) the built-in voltage
          regulator, which can be used to supply power to a test circuit
          through I/O header pins +3V3 and +5V. For example:
               buspirate vreg 0

      -- Command: buspirate led (0|1)
          Turns the Bus Pirate's LED on (1) or off (0).  For example:
          buspirate led 1

8.3 Transport Configuration
===========================

As noted earlier, depending on the version of OpenOCD you use, and the
debug adapter you are using, several transports may be available to
communicate with debug targets (or perhaps to program flash memory).
 -- Command: transport list
     displays the names of the transports supported by this version of
     OpenOCD.

 -- Command: transport select transport_name
     Select which of the supported transports to use in this OpenOCD
     session.

     When invoked with 'transport_name', attempts to select the named
     transport.  The transport must be supported by the debug adapter
     hardware and by the version of OpenOCD you are using (including the
     adapter's driver).

     If no transport has been selected and no 'transport_name' is
     provided, 'transport select' auto-selects the first transport
     supported by the debug adapter.

     'transport select' always returns the name of the session's
     selected transport, if any.

8.3.1 JTAG Transport
--------------------

JTAG is the original transport supported by OpenOCD, and most of the
OpenOCD commands support it.  JTAG transports expose a chain of one or
more Test Access Points (TAPs), each of which must be explicitly
declared.  JTAG supports both debugging and boundary scan testing.
Flash programming support is built on top of debug support.

JTAG transport is selected with the command 'transport select jtag'.
Unless your adapter uses either *note the hla interface driver:
hla_interface. (in which case the command is 'transport select
hla_jtag') or *note the st-link interface driver: st_link_dap_interface.
(in which case the command is 'transport select dapdirect_jtag').

8.3.2 SWD Transport
-------------------

SWD (Serial Wire Debug) is an ARM-specific transport which exposes one
Debug Access Point (DAP, which must be explicitly declared.  (SWD uses
fewer signal wires than JTAG.) SWD is debug-oriented, and does not
support boundary scan testing.  Flash programming support is built on
top of debug support.  (Some processors support both JTAG and SWD.)

SWD transport is selected with the command 'transport select swd'.
Unless your adapter uses either *note the hla interface driver:
hla_interface. (in which case the command is 'transport select hla_swd')
or *note the st-link interface driver: st_link_dap_interface. (in which
case the command is 'transport select dapdirect_swd').

 -- Config Command: swd newdap ...
     Declares a single DAP which uses SWD transport.  Parameters are
     currently the same as "jtag newtap" but this is expected to change.

The newer SWD devices (SW-DP v2 or SWJ-DP v2) support the multi-drop
extension of SWD protocol: two or more devices can be connected to one
SWD adapter.  SWD transport works in multi-drop mode if *note DAP:
dap_create. is configured with both '-dp-id' and '-instance-id'
parameters regardless how many DAPs are created.

Not all adapters and adapter drivers support SWD multi-drop.  Only the
following adapter drivers are SWD multi-drop capable: cmsis_dap (use an
adapter with CMSIS-DAP version 2.0), ftdi, all bitbang based.

8.3.3 SPI Transport
-------------------

The Serial Peripheral Interface (SPI) is a general purpose transport
which uses four wire signaling.  Some processors use it as part of a
solution for flash programming.

8.3.4 SWIM Transport
--------------------

The Single Wire Interface Module (SWIM) is a low-pin-count debug
protocol used by the STMicroelectronics MCU family STM8 and documented
in the User Manual UM470
(https://www.st.com/resource/en/user_manual/cd00173911.pdf).

SWIM does not support boundary scan testing nor multiple cores.

The SWIM transport is selected with the command 'transport select swim'.

The concept of TAPs does not fit in the protocol since SWIM does not
implement a scan chain.  Nevertheless, the current SW model of OpenOCD
requires defining a virtual SWIM TAP through the command 'swim newtap
basename tap_type'.  The TAP definition must precede the target
definition command 'target create target_name stm8 -chain-position
basename.tap_type'.

8.4 JTAG Speed
==============

JTAG clock setup is part of system setup.  It _does not belong with
interface setup_ since any interface only knows a few of the constraints
for the JTAG clock speed.  Sometimes the JTAG speed is changed during
the target initialization process: (1) slow at reset, (2) program the
CPU clocks, (3) run fast.  Both the "slow" and "fast" clock rates are
functions of the oscillators used, the chip, the board design, and
sometimes power management software that may be active.

The speed used during reset, and the scan chain verification which
follows reset, can be adjusted using a 'reset-start' target event
handler.  It can then be reconfigured to a faster speed by a
'reset-init' target event handler after it reprograms those CPU clocks,
or manually (if something else, such as a boot loader, sets up those
clocks).  *Note Target Events: targetevents.  When the initial low JTAG
speed is a chip characteristic, perhaps because of a required oscillator
speed, provide such a handler in the target config file.  When that
speed is a function of a board-specific characteristic such as which
speed oscillator is used, it belongs in the board config file instead.
In both cases it's safest to also set the initial JTAG clock rate to
that same slow speed, so that OpenOCD never starts up using a clock
speed that's faster than the scan chain can support.

     jtag_rclk 3000
     $_TARGET.cpu configure -event reset-start { jtag_rclk 3000 }

If your system supports adaptive clocking (RTCK), configuring JTAG to
use that is probably the most robust approach.  However, it introduces
delays to synchronize clocks; so it may not be the fastest solution.

NOTE: Script writers should consider using 'jtag_rclk' instead of
'adapter speed', but only for (ARM) cores and boards which support
adaptive clocking.

 -- Command: adapter speed max_speed_kHz
     A non-zero speed is in KHZ. Hence: 3000 is 3mhz.  JTAG interfaces
     usually support a limited number of speeds.  The speed actually
     used won't be faster than the speed specified.

     Chip data sheets generally include a top JTAG clock rate.  The
     actual rate is often a function of a CPU core clock, and is
     normally less than that peak rate.  For example, most ARM cores
     accept at most one sixth of the CPU clock.

     Speed 0 (khz) selects RTCK method.  *Note FAQ RTCK: faqrtck.  If
     your system uses RTCK, you won't need to change the JTAG clocking
     after setup.  Not all interfaces, boards, or targets support
     "rtck".  If the interface device can not support it, an error is
     returned when you try to use RTCK.

 -- Function: jtag_rclk fallback_speed_kHz
     This Tcl proc (defined in 'startup.tcl') attempts to enable
     RTCK/RCLK. If that fails (maybe the interface, board, or target
     doesn't support it), falls back to the specified frequency.
          # Fall back to 3mhz if RTCK is not supported
          jtag_rclk 3000


File: openocd.info,  Node: Reset Configuration,  Next: TAP Declaration,  Prev: Debug Adapter Configuration,  Up: Top

9 Reset Configuration
*********************

Every system configuration may require a different reset configuration.
This can also be quite confusing.  Resets also interact with RESET-INIT
event handlers, which do things like setting up clocks and DRAM, and
JTAG clock rates.  (*Note JTAG Speed: jtagspeed.)  They can also
interact with JTAG routers.  Please see the various board files for
examples.

     Note: To maintainers and integrators: Reset configuration touches
     several things at once.  Normally the board configuration file
     should define it and assume that the JTAG adapter supports
     everything that's wired up to the board's JTAG connector.

     However, the target configuration file could also make note of
     something the silicon vendor has done inside the chip, which will
     be true for most (or all) boards using that chip.  And when the
     JTAG adapter doesn't support everything, the user configuration
     file will need to override parts of the reset configuration
     provided by other files.

9.1 Types of Reset
==================

There are many kinds of reset possible through JTAG, but they may not
all work with a given board and adapter.  That's part of why reset
configuration can be error prone.

   * _System Reset_ ...  the _SRST_ hardware signal resets all chips
     connected to the JTAG adapter, such as processors, power management
     chips, and I/O controllers.  Normally resets triggered with this
     signal behave exactly like pressing a RESET button.
   * _JTAG TAP Reset_ ...  the _TRST_ hardware signal resets just the
     TAP controllers connected to the JTAG adapter.  Such resets should
     not be visible to the rest of the system; resetting a device's TAP
     controller just puts that controller into a known state.
   * _Emulation Reset_ ...  many devices can be reset through JTAG
     commands.  These resets are often distinguishable from system
     resets, either explicitly (a "reset reason" register says so) or
     implicitly (not all parts of the chip get reset).
   * _Other Resets_ ...  system-on-chip devices often support several
     other types of reset.  You may need to arrange that a watchdog
     timer stops while debugging, preventing a watchdog reset.  There
     may be individual module resets.

In the best case, OpenOCD can hold SRST, then reset the TAPs via TRST
and send commands through JTAG to halt the CPU at the reset vector
before the 1st instruction is executed.  Then when it finally releases
the SRST signal, the system is halted under debugger control before any
code has executed.  This is the behavior required to support the 'reset
halt' and 'reset init' commands; after 'reset init' a board-specific
script might do things like setting up DRAM. (*Note Reset Command:
resetcommand.)

9.2 SRST and TRST Issues
========================

Because SRST and TRST are hardware signals, they can have a variety of
system-specific constraints.  Some of the most common issues are:

   * _Signal not available_ ...  Some boards don't wire SRST or TRST to
     the JTAG connector.  Some JTAG adapters don't support such signals
     even if they are wired up.  Use the 'reset_config' SIGNALS options
     to say when either of those signals is not connected.  When SRST is
     not available, your code might not be able to rely on controllers
     having been fully reset during code startup.  Missing TRST is not a
     problem, since JTAG-level resets can be triggered using with TMS
     signaling.

   * _Signals shorted_ ...  Sometimes a chip, board, or adapter will
     connect SRST to TRST, instead of keeping them separate.  Use the
     'reset_config' COMBINATION options to say when those signals aren't
     properly independent.

   * _Timing_ ...  Reset circuitry like a resistor/capacitor delay
     circuit, reset supervisor, or on-chip features can extend the
     effect of a JTAG adapter's reset for some time after the adapter
     stops issuing the reset.  For example, there may be chip or board
     requirements that all reset pulses last for at least a certain
     amount of time; and reset buttons commonly have hardware
     debouncing.  Use the 'adapter srst delay' and 'jtag_ntrst_delay'
     commands to say when extra delays are needed.

   * _Drive type_ ...  Reset lines often have a pullup resistor, letting
     the JTAG interface treat them as open-drain signals.  But that's
     not a requirement, so the adapter may need to use push/pull output
     drivers.  Also, with weak pullups it may be advisable to drive
     signals to both levels (push/pull) to minimize rise times.  Use the
     'reset_config' TRST_TYPE and SRST_TYPE parameters to say how to
     drive reset signals.

   * _Special initialization_ ...  Targets sometimes need special JTAG
     initialization sequences to handle chip-specific issues (not
     limited to errata).  For example, certain JTAG commands might need
     to be issued while the system as a whole is in a reset state (SRST
     active) but the JTAG scan chain is usable (TRST inactive).  Many
     systems treat combined assertion of SRST and TRST as a trigger for
     a harder reset than SRST alone.  Such custom reset handling is
     discussed later in this chapter.

There can also be other issues.  Some devices don't fully conform to the
JTAG specifications.  Trivial system-specific differences are common,
such as SRST and TRST using slightly different names.  There are also
vendors who distribute key JTAG documentation for their chips only to
developers who have signed a Non-Disclosure Agreement (NDA).

Sometimes there are chip-specific extensions like a requirement to use
the normally-optional TRST signal (precluding use of JTAG adapters which
don't pass TRST through), or needing extra steps to complete a TAP
reset.

In short, SRST and especially TRST handling may be very finicky, needing
to cope with both architecture and board specific constraints.

9.3 Commands for Handling Resets
================================

 -- Command: adapter srst pulse_width milliseconds
     Minimum amount of time (in milliseconds) OpenOCD should wait after
     asserting nSRST (active-low system reset) before allowing it to be
     deasserted.

 -- Command: adapter srst delay milliseconds
     How long (in milliseconds) OpenOCD should wait after deasserting
     nSRST (active-low system reset) before starting new JTAG
     operations.  When a board has a reset button connected to SRST line
     it will probably have hardware debouncing, implying you should use
     this.

 -- Command: jtag_ntrst_assert_width milliseconds
     Minimum amount of time (in milliseconds) OpenOCD should wait after
     asserting nTRST (active-low JTAG TAP reset) before allowing it to
     be deasserted.

 -- Command: jtag_ntrst_delay milliseconds
     How long (in milliseconds) OpenOCD should wait after deasserting
     nTRST (active-low JTAG TAP reset) before starting new JTAG
     operations.

 -- Command: reset_config mode_flag ...
     This command displays or modifies the reset configuration of your
     combination of JTAG board and target in target configuration
     scripts.

     Information earlier in this section describes the kind of problems
     the command is intended to address (*note SRST and TRST Issues:
     srstandtrstissues.).  As a rule this command belongs only in board
     config files, describing issues like _board doesn't connect TRST_;
     or in user config files, addressing limitations derived from a
     particular combination of interface and board.  (An unlikely
     example would be using a TRST-only adapter with a board that only
     wires up SRST.)

     The MODE_FLAG options can be specified in any order, but only one
     of each type - SIGNALS, COMBINATION, GATES, TRST_TYPE, SRST_TYPE
     and CONNECT_TYPE - may be specified at a time.  If you don't
     provide a new value for a given type, its previous value (perhaps
     the default) is unchanged.  For example, this means that you don't
     need to say anything at all about TRST just to declare that if the
     JTAG adapter should want to drive SRST, it must explicitly be
     driven high ('srst_push_pull').

        * SIGNALS can specify which of the reset signals are connected.
          For example, If the JTAG interface provides SRST, but the
          board doesn't connect that signal properly, then OpenOCD can't
          use it.  Possible values are 'none' (the default),
          'trst_only', 'srst_only' and 'trst_and_srst'.

               Tip: If your board provides SRST and/or TRST through the
               JTAG connector, you must declare that so those signals
               can be used.

        * The COMBINATION is an optional value specifying broken reset
          signal implementations.  The default behaviour if no option
          given is 'separate', indicating everything behaves normally.
          'srst_pulls_trst' states that the test logic is reset together
          with the reset of the system (e.g.  NXP LPC2000, "broken"
          board layout), 'trst_pulls_srst' says that the system is reset
          together with the test logic (only hypothetical, I haven't
          seen hardware with such a bug, and can be worked around).
          'combined' implies both 'srst_pulls_trst' and
          'trst_pulls_srst'.

        * The GATES tokens control flags that describe some cases where
          JTAG may be unavailable during reset.  'srst_gates_jtag'
          (default) indicates that asserting SRST gates the JTAG clock.
          This means that no communication can happen on JTAG while SRST
          is asserted.  Its converse is 'srst_nogate', indicating that
          JTAG commands can safely be issued while SRST is active.

        * The CONNECT_TYPE tokens control flags that describe some cases
          where SRST is asserted while connecting to the target.
          'srst_nogate' is required to use this option.
          'connect_deassert_srst' (default) indicates that SRST will not
          be asserted while connecting to the target.  Its converse is
          'connect_assert_srst', indicating that SRST will be asserted
          before any target connection.  Only some targets support this
          feature, STM32 and STR9 are examples.  This feature is useful
          if you are unable to connect to your target due to incorrect
          options byte config or illegal program execution.

     The optional TRST_TYPE and SRST_TYPE parameters allow the driver
     mode of each reset line to be specified.  These values only affect
     JTAG interfaces with support for different driver modes, like the
     Amontec JTAGkey and JTAG Accelerator.  Also, they are necessarily
     ignored if the relevant signal (TRST or SRST) is not connected.

        * Possible TRST_TYPE driver modes for the test reset signal
          (TRST) are the default 'trst_push_pull', and
          'trst_open_drain'.  Most boards connect this signal to a
          pulldown, so the JTAG TAPs never leave reset unless they are
          hooked up to a JTAG adapter.

        * Possible SRST_TYPE driver modes for the system reset signal
          (SRST) are the default 'srst_open_drain', and
          'srst_push_pull'.  Most boards connect this signal to a
          pullup, and allow the signal to be pulled low by various
          events including system power-up and pressing a reset button.

9.4 Custom Reset Handling
=========================

OpenOCD has several ways to help support the various reset mechanisms
provided by chip and board vendors.  The commands shown in the previous
section give standard parameters.  There are also _event handlers_
associated with TAPs or Targets.  Those handlers are Tcl procedures you
can provide, which are invoked at particular points in the reset
sequence.

_When SRST is not an option_ you must set up a 'reset-assert' event
handler for your target.  For example, some JTAG adapters don't include
the SRST signal; and some boards have multiple targets, and you won't
always want to reset everything at once.

After configuring those mechanisms, you might still find your board
doesn't start up or reset correctly.  For example, maybe it needs a
slightly different sequence of SRST and/or TRST manipulations, because
of quirks that the 'reset_config' mechanism doesn't address; or
asserting both might trigger a stronger reset, which needs special
attention.

Experiment with lower level operations, such as 'adapter assert',
'adapter deassert' and the 'jtag arp_*' operations shown here, to find a
sequence of operations that works.  *Note JTAG Commands::.  When you
find a working sequence, it can be used to override 'jtag_init', which
fires during OpenOCD startup (*note Configuration Stage:
configurationstage.); or 'init_reset', which fires during reset
processing.

You might also want to provide some project-specific reset schemes.  For
example, on a multi-target board the standard 'reset' command would
reset all targets, but you may need the ability to reset only one target
at time and thus want to avoid using the board-wide SRST signal.

 -- Overridable Procedure: init_reset mode
     This is invoked near the beginning of the 'reset' command, usually
     to provide as much of a cold (power-up) reset as practical.  By
     default it is also invoked from 'jtag_init' if the scan chain does
     not respond to pure JTAG operations.  The MODE parameter is the
     parameter given to the low level reset command ('halt', 'init', or
     'run'), 'setup', or potentially some other value.

     The default implementation just invokes 'jtag arp_init-reset'.
     Replacements will normally build on low level JTAG operations such
     as 'adapter assert' and 'adapter deassert'.  Operations here must
     not address individual TAPs (or their associated targets) until the
     JTAG scan chain has first been verified to work.

     Implementations must have verified the JTAG scan chain before they
     return.  This is done by calling 'jtag arp_init' (or 'jtag
     arp_init-reset').

 -- Command: jtag arp_init
     This validates the scan chain using just the four standard JTAG
     signals (TMS, TCK, TDI, TDO). It starts by issuing a JTAG-only
     reset.  Then it performs checks to verify that the scan chain
     configuration matches the TAPs it can observe.  Those checks
     include checking IDCODE values for each active TAP, and verifying
     the length of their instruction registers using TAP '-ircapture'
     and '-irmask' values.  If these tests all pass, TAP 'setup' events
     are issued to all TAPs with handlers for that event.

 -- Command: jtag arp_init-reset
     This uses TRST and SRST to try resetting everything on the JTAG
     scan chain (and anything else connected to SRST). It then invokes
     the logic of 'jtag arp_init'.


File: openocd.info,  Node: TAP Declaration,  Next: CPU Configuration,  Prev: Reset Configuration,  Up: Top

10 TAP Declaration
******************

_Test Access Ports_ (TAPs) are the core of JTAG. TAPs serve many roles,
including:

   * Debug Target A CPU TAP can be used as a GDB debug target.
   * Flash Programming Some chips program the flash directly via JTAG.
     Others do it indirectly, making a CPU do it.
   * Program Download Using the same CPU support GDB uses, you can
     initialize a DRAM controller, download code to DRAM, and then start
     running that code.
   * Boundary Scan Most chips support boundary scan, which helps test
     for board assembly problems like solder bridges and missing
     connections.

OpenOCD must know about the active TAPs on your board(s).  Setting up
the TAPs is the core task of your configuration files.  Once those TAPs
are set up, you can pass their names to code which sets up CPUs and
exports them as GDB targets, probes flash memory, performs low-level
JTAG operations, and more.

10.1 Scan Chains
================

TAPs are part of a hardware "scan chain", which is a daisy chain of
TAPs.  They also need to be added to OpenOCD's software mirror of that
hardware list, giving each member a name and associating other data with
it.  Simple scan chains, with a single TAP, are common in systems with a
single microcontroller or microprocessor.  More complex chips may have
several TAPs internally.  Very complex scan chains might have a dozen or
more TAPs: several in one chip, more in the next, and connecting to
other boards with their own chips and TAPs.

You can display the list with the 'scan_chain' command.  (Don't confuse
this with the list displayed by the 'targets' command, presented in the
next chapter.  That only displays TAPs for CPUs which are configured as
debugging targets.)  Here's what the scan chain might look like for a
chip more than one TAP:

   TapName            Enabled IdCode     Expected   IrLen IrCap IrMask
-- ------------------ ------- ---------- ---------- ----- ----- ------
 0 omap5912.dsp          Y    0x03df1d81 0x03df1d81    38 0x01  0x03
 1 omap5912.arm          Y    0x0692602f 0x0692602f     4 0x01  0x0f
 2 omap5912.unknown      Y    0x00000000 0x00000000     8 0x01  0x03

OpenOCD can detect some of that information, but not all of it.  *Note
Autoprobing: autoprobing.  Unfortunately, those TAPs can't always be
autoconfigured, because not all devices provide good support for that.
JTAG doesn't require supporting IDCODE instructions, and chips with JTAG
routers may not link TAPs into the chain until they are told to do so.

The configuration mechanism currently supported by OpenOCD requires
explicit configuration of all TAP devices using 'jtag newtap' commands,
as detailed later in this chapter.  A command like this would declare
one tap and name it 'chip1.cpu':

     jtag newtap chip1 cpu -irlen 4 -expected-id 0x3ba00477

Each target configuration file lists the TAPs provided by a given chip.
Board configuration files combine all the targets on a board, and so
forth.  Note that _the order in which TAPs are declared is very
important._  That declaration order must match the order in the JTAG
scan chain, both inside a single chip and between them.  *Note FAQ TAP
Order: faqtaporder.

For example, the STMicroelectronics STR912 chip has three separate
TAPs(1).  To configure those taps, 'target/str912.cfg' includes commands
something like this:

     jtag newtap str912 flash ... params ...
     jtag newtap str912 cpu ... params ...
     jtag newtap str912 bs ... params ...

Actual config files typically use a variable such as '$_CHIPNAME'
instead of literals like 'str912', to support more than one chip of each
type.  *Note Config File Guidelines::.

 -- Command: jtag names
     Returns the names of all current TAPs in the scan chain.  Use 'jtag
     cget' or 'jtag tapisenabled' to examine attributes and state of
     each TAP.
          foreach t [jtag names] {
              puts [format "TAP: %s\n" $t]
          }

 -- Command: scan_chain
     Displays the TAPs in the scan chain configuration, and their
     status.  The set of TAPs listed by this command is fixed by exiting
     the OpenOCD configuration stage, but systems with a JTAG router can
     enable or disable TAPs dynamically.

10.2 TAP Names
==============

When TAP objects are declared with 'jtag newtap', a "dotted.name" is
created for the TAP, combining the name of a module (usually a chip) and
a label for the TAP. For example: 'xilinx.tap', 'str912.flash',
'omap3530.jrc', 'dm6446.dsp', or 'stm32.cpu'.  Many other commands use
that dotted.name to manipulate or refer to the TAP. For example, CPU
configuration uses the name, as does declaration of NAND or NOR flash
banks.

The components of a dotted name should follow "C" symbol name rules:
start with an alphabetic character, then numbers and underscores are OK;
while others (including dots!)  are not.

10.3 TAP Declaration Commands
=============================

 -- Config Command: jtag newtap chipname tapname configparams...
     Declares a new TAP with the dotted name CHIPNAME.TAPNAME, and
     configured according to the various CONFIGPARAMS.

     The CHIPNAME is a symbolic name for the chip.  Conventionally
     target config files use '$_CHIPNAME', defaulting to the model name
     given by the chip vendor but overridable.

     The TAPNAME reflects the role of that TAP, and should follow this
     convention:

        * 'bs' - For boundary scan if this is a separate TAP;
        * 'cpu' - The main CPU of the chip, alternatively 'arm' and
          'dsp' on chips with both ARM and DSP CPUs, 'arm1' and 'arm2'
          on chips with two ARMs, and so forth;
        * 'etb' - For an embedded trace buffer (example: an ARM ETB11);
        * 'flash' - If the chip has a flash TAP, like the str912;
        * 'jrc' - For JTAG route controller (example: the ICEPick
          modules on many Texas Instruments chips, like the OMAP3530 on
          Beagleboards);
        * 'tap' - Should be used only for FPGA- or CPLD-like devices
          with a single TAP;
        * 'unknownN' - If you have no idea what the TAP is for (N is a
          number);
        * _when in doubt_ - Use the chip maker's name in their data
          sheet.  For example, the Freescale i.MX31 has a SDMA (Smart
          DMA) with a JTAG TAP; that TAP should be named 'sdma'.

     Every TAP requires at least the following CONFIGPARAMS:

        * '-irlen' NUMBER
          The length in bits of the instruction register, such as 4 or 5
          bits.

     A TAP may also provide optional CONFIGPARAMS:

        * '-disable' (or '-enable')
          Use the '-disable' parameter to flag a TAP which is not linked
          into the scan chain after a reset using either TRST or the
          JTAG state machine's RESET state.  You may use '-enable' to
          highlight the default state (the TAP is linked in).  *Note
          Enabling and Disabling TAPs: enablinganddisablingtaps.
        * '-expected-id' NUMBER
          A non-zero NUMBER represents a 32-bit IDCODE which you expect
          to find when the scan chain is examined.  These codes are not
          required by all JTAG devices.  _Repeat the option_ as many
          times as required if more than one ID code could appear (for
          example, multiple versions).  Specify NUMBER as zero to
          suppress warnings about IDCODE values that were found but not
          included in the list.

          Provide this value if at all possible, since it lets OpenOCD
          tell when the scan chain it sees isn't right.  These values
          are provided in vendors' chip documentation, usually a
          technical reference manual.  Sometimes you may need to probe
          the JTAG hardware to find these values.  *Note Autoprobing:
          autoprobing.
        * '-ignore-version'
          Specify this to ignore the JTAG version field in the
          '-expected-id' option.  When vendors put out multiple versions
          of a chip, or use the same JTAG-level ID for several
          largely-compatible chips, it may be more practical to ignore
          the version field than to update config files to handle all of
          the various chip IDs.  The version field is defined as bit
          28-31 of the IDCODE.
        * '-ignore-bypass'
          Specify this to ignore the 'bypass' bit of the idcode.  Some
          vendor put an invalid idcode regarding this bit.  Specify this
          to ignore this bit and to not consider this tap in bypass
          mode.
        * '-ircapture' NUMBER
          The bit pattern loaded by the TAP into the JTAG shift register
          on entry to the IRCAPTURE state, such as 0x01.  JTAG requires
          the two LSBs of this value to be 01.  By default, '-ircapture'
          and '-irmask' are set up to verify that two-bit value.  You
          may provide additional bits if you know them, or indicate that
          a TAP doesn't conform to the JTAG specification.
        * '-irmask' NUMBER
          A mask used with '-ircapture' to verify that instruction scans
          work correctly.  Such scans are not used by OpenOCD except to
          verify that there seems to be no problems with JTAG scan chain
          operations.
        * '-ignore-syspwrupack'
          Specify this to ignore the CSYSPWRUPACK bit in the ARM DAP DP
          CTRL/STAT register during initial examination and when
          checking the sticky error bit.  This bit is normally checked
          after setting the CSYSPWRUPREQ bit, but some devices do not
          set the ack bit until sometime later.

10.4 Other TAP commands
=======================

 -- Command: jtag cget dotted.name -idcode
     Get the value of the IDCODE found in hardware.

 -- Command: jtag cget dotted.name -event event_name
 -- Command: jtag configure dotted.name -event event_name handler
     At this writing this TAP attribute mechanism is limited and used
     mostly for event handling.  (It is not a direct analogue of the
     'cget'/'configure' mechanism for debugger targets.)  See the next
     section for information about the available events.

     The 'configure' subcommand assigns an event handler, a TCL string
     which is evaluated when the event is triggered.  The 'cget'
     subcommand returns that handler.

10.5 TAP Events
===============

OpenOCD includes two event mechanisms.  The one presented here applies
to all JTAG TAPs.  The other applies to debugger targets, which are
associated with certain TAPs.

The TAP events currently defined are:

   * post-reset
     The TAP has just completed a JTAG reset.  The tap may still be in
     the JTAG RESET state.  Handlers for these events might perform
     initialization sequences such as issuing TCK cycles, TMS sequences
     to ensure exit from the ARM SWD mode, and more.

     Because the scan chain has not yet been verified, handlers for
     these events _should not issue commands which scan the JTAG IR or
     DR registers_ of any particular target.  NOTE: As this is written
     (September 2009), nothing prevents such access.
   * setup
     The scan chain has been reset and verified.  This handler may
     enable TAPs as needed.
   * tap-disable
     The TAP needs to be disabled.  This handler should implement 'jtag
     tapdisable' by issuing the relevant JTAG commands.
   * tap-enable
     The TAP needs to be enabled.  This handler should implement 'jtag
     tapenable' by issuing the relevant JTAG commands.

If you need some action after each JTAG reset which isn't actually
specific to any TAP (since you can't yet trust the scan chain's contents
to be accurate), you might:

     jtag configure CHIP.jrc -event post-reset {
       echo "JTAG Reset done"
       ... non-scan jtag operations to be done after reset
     }

10.6 Enabling and Disabling TAPs
================================

In some systems, a "JTAG Route Controller" (JRC) is used to enable
and/or disable specific JTAG TAPs.  Many ARM-based chips from Texas
Instruments include an "ICEPick" module, which is a JRC. Such chips
include DaVinci and OMAP3 processors.

A given TAP may not be visible until the JRC has been told to link it
into the scan chain; and if the JRC has been told to unlink that TAP, it
will no longer be visible.  Such routers address problems that JTAG
"bypass mode" ignores, such as:

   * The scan chain can only go as fast as its slowest TAP.
   * Having many TAPs slows instruction scans, since all TAPs receive
     new instructions.
   * TAPs in the scan chain must be powered up, which wastes power and
     prevents debugging some power management mechanisms.

The IEEE 1149.1 JTAG standard has no concept of a "disabled" tap, as
implied by the existence of JTAG routers.  However, the upcoming IEEE
1149.7 framework (layered on top of JTAG) does include a kind of JTAG
router functionality.

In OpenOCD, tap enabling/disabling is invoked by the Tcl commands shown
below, and is implemented using TAP event handlers.  So for example,
when defining a TAP for a CPU connected to a JTAG router, your
'target.cfg' file should define TAP event handlers using code that looks
something like this:

     jtag configure CHIP.cpu -event tap-enable {
       ... jtag operations using CHIP.jrc
     }
     jtag configure CHIP.cpu -event tap-disable {
       ... jtag operations using CHIP.jrc
     }

Then you might want that CPU's TAP enabled almost all the time:

     jtag configure $CHIP.jrc -event setup "jtag tapenable $CHIP.cpu"

Note how that particular setup event handler declaration uses quotes to
evaluate '$CHIP' when the event is configured.  Using brackets { } would
cause it to be evaluated later, at runtime, when it might have a
different value.

 -- Command: jtag tapdisable dotted.name
     If necessary, disables the tap by sending it a 'tap-disable' event.
     Returns the string "1" if the tap specified by DOTTED.NAME is
     enabled, and "0" if it is disabled.

 -- Command: jtag tapenable dotted.name
     If necessary, enables the tap by sending it a 'tap-enable' event.
     Returns the string "1" if the tap specified by DOTTED.NAME is
     enabled, and "0" if it is disabled.

 -- Command: jtag tapisenabled dotted.name
     Returns the string "1" if the tap specified by DOTTED.NAME is
     enabled, and "0" if it is disabled.

          Note: Humans will find the 'scan_chain' command more helpful
          for querying the state of the JTAG taps.

10.7 Autoprobing
================

TAP configuration is the first thing that needs to be done after
interface and reset configuration.  Sometimes it's hard finding out what
TAPs exist, or how they are identified.  Vendor documentation is not
always easy to find and use.

To help you get past such problems, OpenOCD has a limited _autoprobing_
ability to look at the scan chain, doing a "blind interrogation" and
then reporting the TAPs it finds.  To use this mechanism, start the
OpenOCD server with only data that configures your JTAG interface, and
arranges to come up with a slow clock (many devices don't support fast
JTAG clocks right when they come out of reset).

For example, your 'openocd.cfg' file might have:

     source [find interface/olimex-arm-usb-tiny-h.cfg]
     reset_config trst_and_srst
     jtag_rclk 8

When you start the server without any TAPs configured, it will attempt
to autoconfigure the TAPs.  There are two parts to this:

  1. _TAP discovery_ ...  After a JTAG reset (sometimes a system reset
     may be needed too), each TAP's data registers will hold the
     contents of either the IDCODE or BYPASS register.  If JTAG
     communication is working, OpenOCD will see each TAP, and report
     what '-expected-id' to use with it.
  2. _IR Length discovery_ ...  Unfortunately JTAG does not provide a
     reliable way to find out the value of the '-irlen' parameter to use
     with a TAP that is discovered.  If OpenOCD can discover the length
     of a TAP's instruction register, it will report it.  Otherwise you
     may need to consult vendor documentation, such as chip data sheets
     or BSDL files.

In many cases your board will have a simple scan chain with just a
single device.  Here's what OpenOCD reported with one board that's a bit
more complex:

     clock speed 8 kHz
     There are no enabled taps. AUTO PROBING MIGHT NOT WORK!!
     AUTO auto0.tap - use "jtag newtap auto0 tap -expected-id 0x2b900f0f ..."
     AUTO auto1.tap - use "jtag newtap auto1 tap -expected-id 0x07926001 ..."
     AUTO auto2.tap - use "jtag newtap auto2 tap -expected-id 0x0b73b02f ..."
     AUTO auto0.tap - use "... -irlen 4"
     AUTO auto1.tap - use "... -irlen 4"
     AUTO auto2.tap - use "... -irlen 6"
     no gdb ports allocated as no target has been specified

Given that information, you should be able to either find some existing
config files to use, or create your own.  If you create your own, you
would configure from the bottom up: first a 'target.cfg' file with these
TAPs, any targets associated with them, and any on-chip resources; then
a 'board.cfg' with off-chip resources, clocking, and so forth.

10.8 DAP declaration (ARMv6-M, ARMv7 and ARMv8 targets)
=======================================================

Since OpenOCD version 0.11.0, the Debug Access Port (DAP) is no longer
implicitly created together with the target.  It must be explicitly
declared using the 'dap create' command.  For all ARMv6-M, ARMv7 and
ARMv8 targets, the option "'-dap' DAP_NAME" has to be used instead of
"'-chain-position' DOTTED.NAME" when the target is created.

The 'dap' command group supports the following sub-commands:

 -- Command: dap create dap_name -chain-position dotted.name
          configparams...
     Declare a DAP instance named DAP_NAME linked to the JTAG tap
     DOTTED.NAME.  This also creates a new command ('dap_name') which is
     used for various purposes including additional configuration.
     There can only be one DAP for each JTAG tap in the system.

     A DAP may also provide optional CONFIGPARAMS:

        * '-ignore-syspwrupack'
          Specify this to ignore the CSYSPWRUPACK bit in the ARM DAP DP
          CTRL/STAT register during initial examination and when
          checking the sticky error bit.  This bit is normally checked
          after setting the CSYSPWRUPREQ bit, but some devices do not
          set the ack bit until sometime later.

        * '-dp-id' NUMBER
          Debug port identification number for SWD DPv2 multidrop.  The
          NUMBER is written to bits 0..27 of DP TARGETSEL during DP
          selection.  To find the id number of a single connected device
          read DP TARGETID: 'device.dap dpreg 0x24' Use bits 0..27 of
          TARGETID.

        * '-instance-id' NUMBER
          Instance identification number for SWD DPv2 multidrop.  The
          NUMBER is written to bits 28..31 of DP TARGETSEL during DP
          selection.  To find the instance number of a single connected
          device read DP DLPIDR: 'device.dap dpreg 0x34' The instance
          number is in bits 28..31 of DLPIDR value.

 -- Command: dap names
     This command returns a list of all registered DAP objects.  It it
     useful mainly for TCL scripting.

 -- Command: dap info [num]
     Displays the ROM table for MEM-AP NUM, defaulting to the currently
     selected AP of the currently selected target.

 -- Command: dap init
     Initialize all registered DAPs.  This command is used internally
     during initialization.  It can be issued at any time after the
     initialization, too.

The following commands exist as subcommands of DAP instances:

 -- Command: $dap_name info [num]
     Displays the ROM table for MEM-AP NUM, defaulting to the currently
     selected AP.

 -- Command: $dap_name apid [num]
     Displays ID register from AP NUM, defaulting to the currently
     selected AP.

 -- Command: $dap_name apreg ap_num reg [value]
     Displays content of a register REG from AP AP_NUM or set a new
     value VALUE.  REG is byte address of a word register, 0, 4, 8 ...
     0xfc.

 -- Command: $dap_name apsel [num]
     Select AP NUM, defaulting to 0.

 -- Command: $dap_name dpreg reg [value]
     Displays the content of DP register at address REG, or set it to a
     new value VALUE.

     In case of SWD, REG is a value in packed format dpbanksel << 4 |
     addr and assumes values 0, 4, 8 ...  0xfc.  In case of JTAG it only
     assumes values 0, 4, 8 and 0xc.

     _Note:_ Consider using 'poll off' to avoid any disturbing
     background activity by OpenOCD while you are operating at such
     low-level.

 -- Command: $dap_name baseaddr [num]
     Displays debug base address from MEM-AP NUM, defaulting to the
     currently selected AP.

 -- Command: $dap_name memaccess [value]
     Displays the number of extra tck cycles in the JTAG idle to use for
     MEM-AP memory bus access [0-255], giving additional time to respond
     to reads.  If VALUE is defined, first assigns that.

 -- Command: $dap_name apcsw [value [mask]]
     Displays or changes CSW bit pattern for MEM-AP transfers.

     At the begin of each memory access the CSW pattern is extended
     (bitwise or-ed) by "Size" and "AddrInc" bit-fields according to
     transfer requirements and the result is written to the real CSW
     register.  All bits except dynamically updated fields "Size" and
     "AddrInc" can be changed by changing the CSW pattern.  Refer to ARM
     ADI v5 manual chapter 7.6.4 and appendix A for details.

     Use VALUE only syntax if you want to set the new CSW pattern as a
     whole.  The example sets HPROT1 bit (required by Cortex-M) and
     clears the rest of the pattern:
          kx.dap apcsw 0x2000000

     If MASK is also used, the CSW pattern is changed only on bit
     positions where the mask bit is 1.  The following example sets
     HPROT3 (cacheable) and leaves the rest of the pattern intact.  It
     configures memory access through DCache on Cortex-M7.
          set CSW_HPROT3_CACHEABLE [expr {1 << 27}]
          samv.dap apcsw $CSW_HPROT3_CACHEABLE $CSW_HPROT3_CACHEABLE

     Another example clears SPROT bit and leaves the rest of pattern
     intact:
          set CSW_SPROT [expr {1 << 30}]
          samv.dap apcsw 0 $CSW_SPROT

     _Note:_ If you want to check the real value of CSW, not CSW
     pattern, use 'xxx.dap apreg 0'.  *Note DAP subcommand apreg::.

     _Warning:_ Some of the CSW bits are vital for working memory
     transfer.  If you set a wrong CSW pattern and MEM-AP stopped
     working, use the following example with a proper dap name:
          xxx.dap apcsw default

 -- Config Command: $dap_name ti_be_32_quirks [enable]
     Set/get quirks mode for TI TMS450/TMS570 processors Disabled by
     default

   ---------- Footnotes ----------

   (1) See the ST document titled: _STR91xFAxxx, Section 3.15 Jtag
Interface, Page: 28/102, Figure 3: JTAG chaining inside the STR91xFA_.
<http://eu.st.com/stonline/products/literature/ds/13495.pdf>


File: openocd.info,  Node: CPU Configuration,  Next: Flash Commands,  Prev: TAP Declaration,  Up: Top

11 CPU Configuration
********************

This chapter discusses how to set up GDB debug targets for CPUs.  You
can also access these targets without GDB (*note Architecture and Core
Commands::, and *note Target State handling: targetstatehandling.) and
through various kinds of NAND and NOR flash commands.  If you have
multiple CPUs you can have multiple such targets.

We'll start by looking at how to examine the targets you have, then look
at how to add one more target and how to configure it.

11.1 Target List
================

All targets that have been set up are part of a list, where each member
has a name.  That name should normally be the same as the TAP name.  You
can display the list with the 'targets' (plural!)  command.  This
display often has only one CPU; here's what it might look like with more
than one:
    TargetName         Type       Endian TapName            State
--  ------------------ ---------- ------ ------------------ ------------
 0* at91rm9200.cpu     arm920t    little at91rm9200.cpu     running
 1  MyTarget           cortex_m   little mychip.foo         tap-disabled

One member of that list is the "current target", which is implicitly
referenced by many commands.  It's the one marked with a '*' near the
target name.  In particular, memory addresses often refer to the address
space seen by that current target.  Commands like 'mdw' (memory display
words) and 'flash erase_address' (erase NOR flash blocks) are examples;
and there are many more.

Several commands let you examine the list of targets:

 -- Command: target current
     Returns the name of the current target.

 -- Command: target names
     Lists the names of all current targets in the list.
          foreach t [target names] {
              puts [format "Target: %s\n" $t]
          }

 -- Command: targets [name]
     _Note: the name of this command is plural.  Other target command
     names are singular._

     With no parameter, this command displays a table of all known
     targets in a user friendly form.

     With a parameter, this command sets the current target to the given
     target with the given NAME; this is only relevant on boards which
     have more than one target.

11.2 Target CPU Types
=====================

Each target has a "CPU type", as shown in the output of the 'targets'
command.  You need to specify that type when calling 'target create'.
The CPU type indicates more than just the instruction set.  It also
indicates how that instruction set is implemented, what kind of debug
support it integrates, whether it has an MMU (and if so, what kind),
what core-specific commands may be available (*note Architecture and
Core Commands::), and more.

It's easy to see what target types are supported, since there's a
command to list them.

 -- Command: target types
     Lists all supported target types.  At this writing, the supported
     CPU types are:

        * 'aarch64' - this is an ARMv8-A core with an MMU.
        * 'arm11' - this is a generation of ARMv6 cores.
        * 'arm720t' - this is an ARMv4 core with an MMU.
        * 'arm7tdmi' - this is an ARMv4 core.
        * 'arm920t' - this is an ARMv4 core with an MMU.
        * 'arm926ejs' - this is an ARMv5 core with an MMU.
        * 'arm946e' - this is an ARMv5 core with an MMU.
        * 'arm966e' - this is an ARMv5 core.
        * 'arm9tdmi' - this is an ARMv4 core.
        * 'avr' - implements Atmel's 8-bit AVR instruction set.
          (Support for this is preliminary and incomplete.)
        * 'avr32_ap7k' - this an AVR32 core.
        * 'cortex_a' - this is an ARMv7-A core with an MMU.
        * 'cortex_m' - this is an ARMv7-M core, supporting only the
          compact Thumb2 instruction set.  Supports also ARMv6-M and
          ARMv8-M cores
        * 'cortex_r4' - this is an ARMv7-R core.
        * 'dragonite' - resembles arm966e.
        * 'dsp563xx' - implements Freescale's 24-bit DSP. (Support for
          this is still incomplete.)
        * 'dsp5680xx' - implements Freescale's 5680x DSP.
        * 'esirisc' - this is an EnSilica eSi-RISC core.  The current
          implementation supports eSi-32xx cores.
        * 'fa526' - resembles arm920 (w/o Thumb).
        * 'feroceon' - resembles arm926.
        * 'hla_target' - a Cortex-M alternative to work with HL adapters
          like ST-Link.
        * 'ls1_sap' - this is the SAP on NXP LS102x CPUs, allowing
          access to physical memory addresses independently of CPU
          cores.
        * 'mem_ap' - this is an ARM debug infrastructure Access Port
          without a CPU, through which bus read and write cycles can be
          generated; it may be useful for working with non-CPU hardware
          behind an AP or during development of support for new CPUs.
          It's possible to connect a GDB client to this target (the GDB
          port has to be specified, *Note option -gdb-port:
          gdbportoverride.), and a fake ARM core will be emulated to
          comply to GDB remote protocol.
        * 'mips_m4k' - a MIPS core.
        * 'mips_mips64' - a MIPS64 core.
        * 'nds32_v2' - this is an Andes NDS32 v2 core.
        * 'nds32_v3' - this is an Andes NDS32 v3 core.
        * 'nds32_v3m' - this is an Andes NDS32 v3m core.
        * 'or1k' - this is an OpenRISC 1000 core.  The current
          implementation supports three JTAG TAP cores:
             - 'OpenCores TAP' (See:
               <http://opencores.org/project,jtag>)
             - 'Altera Virtual JTAG TAP' (See:
               <http://www.altera.com/literature/ug/ug_virtualjtag.pdf>)
             - 'Xilinx BSCAN_* virtual JTAG interface' (See:
               <http://www.xilinx.com/support/documentation/sw_manuals/xilinx14_2/spartan6_hdl.pdf>)
          And two debug interfaces cores:
             - 'Advanced debug interface'
               (See: <http://opencores.org/project,adv_debug_sys>)
             - 'SoC Debug Interface'
               (See: <http://opencores.org/project,dbg_interface>)
        * 'quark_d20xx' - an Intel Quark D20xx core.
        * 'quark_x10xx' - an Intel Quark X10xx core.
        * 'riscv' - a RISC-V core.
        * 'stm8' - implements an STM8 core.
        * 'testee' - a dummy target for cases without a real CPU, e.g.
          CPLD.
        * 'xscale' - this is actually an architecture, not a CPU type.
          It is based on the ARMv5 architecture.

To avoid being confused by the variety of ARM based cores, remember this
key point: _ARM is a technology licencing company_.  (See:
<http://www.arm.com>.)  The CPU name used by OpenOCD will reflect the
CPU design that was licensed, not a vendor brand which incorporates that
design.  Name prefixes like arm7, arm9, arm11, and cortex reflect design
generations; while names like ARMv4, ARMv5, ARMv6, ARMv7 and ARMv8
reflect an architecture version implemented by a CPU design.

11.3 Target Configuration
=========================

Before creating a "target", you must have added its TAP to the scan
chain.  When you've added that TAP, you will have a 'dotted.name' which
is used to set up the CPU support.  The chip-specific configuration file
will normally configure its CPU(s) right after it adds all of the chip's
TAPs to the scan chain.

Although you can set up a target in one step, it's often clearer if you
use shorter commands and do it in two steps: create it, then configure
optional parts.  All operations on the target after it's created will
use a new command, created as part of target creation.

The two main things to configure after target creation are a work area,
which usually has target-specific defaults even if the board setup code
overrides them later; and event handlers (*note Target Events:
targetevents.), which tend to be much more board-specific.  The key
steps you use might look something like this

     dap create mychip.dap -chain-position mychip.cpu
     target create MyTarget cortex_m -dap mychip.dap
     MyTarget configure -work-area-phys 0x08000 -work-area-size 8096
     MyTarget configure -event reset-deassert-pre { jtag_rclk 5 }
     MyTarget configure -event reset-init { myboard_reinit }

You should specify a working area if you can; typically it uses some
on-chip SRAM. Such a working area can speed up many things, including
bulk writes to target memory; flash operations like checking to see if
memory needs to be erased; GDB memory checksumming; and more.

     Warning: On more complex chips, the work area can become
     inaccessible when application code (such as an operating system)
     enables or disables the MMU. For example, the particular MMU
     context used to access the virtual address will probably matter ...
     and that context might not have easy access to other addresses
     needed.  At this writing, OpenOCD doesn't have much MMU
     intelligence.

It's often very useful to define a 'reset-init' event handler.  For
systems that are normally used with a boot loader, common tasks include
updating clocks and initializing memory controllers.  That may be needed
to let you write the boot loader into flash, in order to "de-brick" your
board; or to load programs into external DDR memory without having run
the boot loader.

 -- Config Command: target create target_name type configparams...
     This command creates a GDB debug target that refers to a specific
     JTAG tap.  It enters that target into a list, and creates a new
     command ('TARGET_NAME') which is used for various purposes
     including additional configuration.

        * TARGET_NAME ...  is the name of the debug target.  By
          convention this should be the same as the _dotted.name_ of the
          TAP associated with this target, which must be specified here
          using the '-chain-position DOTTED.NAME' configparam.

          This name is also used to create the target object command,
          referred to here as '$target_name', and in other places the
          target needs to be identified.
        * TYPE ...  specifies the target type.  *Note target types:
          targettypes.
        * CONFIGPARAMS ...  all parameters accepted by '$target_name
          configure' are permitted.  If the target is big-endian, set it
          here with '-endian big'.

          You _must_ set the '-chain-position DOTTED.NAME' or '-dap
          DAP_NAME' here.

 -- Command: $target_name configure configparams...
     The options accepted by this command may also be specified as
     parameters to 'target create'.  Their values can later be queried
     one at a time by using the '$target_name cget' command.

     _Warning:_ changing some of these after setup is dangerous.  For
     example, moving a target from one TAP to another; and changing its
     endianness.

        * '-chain-position' DOTTED.NAME - names the TAP used to access
          this target.

        * '-dap' DAP_NAME - names the DAP used to access this target.
          *Note DAP declaration: dapdeclaration, on how to create and
          manage DAP instances.

        * '-endian' ('big'|'little') - specifies whether the CPU uses
          big or little endian conventions

        * '-event' EVENT_NAME EVENT_BODY - *Note Target Events:
          targetevents.  Note that this updates a list of named event
          handlers.  Calling this twice with two different event names
          assigns two different handlers, but calling it twice with the
          same event name assigns only one handler.

          Current target is temporarily overridden to the event issuing
          target before handler code starts and switched back after
          handler is done.

        * '-work-area-backup' ('0'|'1') - says whether the work area
          gets backed up; by default, _it is not backed up._  When
          possible, use a working_area that doesn't need to be backed
          up, since performing a backup slows down operations.  For
          example, the beginning of an SRAM block is likely to be used
          by most build systems, but the end is often unused.

        * '-work-area-size' SIZE - specify work are size, in bytes.  The
          same size applies regardless of whether its physical or
          virtual address is being used.

        * '-work-area-phys' ADDRESS - set the work area base ADDRESS to
          be used when no MMU is active.

        * '-work-area-virt' ADDRESS - set the work area base ADDRESS to
          be used when an MMU is active.  _Do not specify a value for
          this except on targets with an MMU._ The value should normally
          correspond to a static mapping for the '-work-area-phys'
          address, set up by the current operating system.

        * '-rtos' RTOS_TYPE - enable rtos support for target, RTOS_TYPE
          can be one of 'auto', 'eCos', 'ThreadX', 'FreeRTOS', 'linux',
          'ChibiOS', 'embKernel', 'mqx', 'uCOS-III', 'nuttx', 'RIOT',
          'Zephyr' *Note RTOS Support: gdbrtossupport.

        * '-defer-examine' - skip target examination at initial JTAG
          chain scan and after a reset.  A manual call to arp_examine is
          required to access the target for debugging.

        * '-ap-num' AP_NUMBER - set DAP access port for target,
          AP_NUMBER is the numeric index of the DAP AP the target is
          connected to.  Use this option with systems where multiple,
          independent cores are connected to separate access ports of
          the same DAP.

        * '-cti' CTI_NAME - set Cross-Trigger Interface (CTI) connected
          to the target.  Currently, only the 'aarch64' target makes use
          of this option, where it is a mandatory configuration for the
          target run control.  *Note ARM Cross-Trigger Interface:
          armcrosstrigger, for instruction on how to declare and control
          a CTI instance.

        * '-gdb-port' NUMBER - see command 'gdb_port' for the possible
          values of the parameter NUMBER, which are not only numeric
          values.  Use this option to override, for this target only,
          the global parameter set with command 'gdb_port'.  *Note
          command gdb_port: gdb_port.

        * '-gdb-max-connections' NUMBER - EXPERIMENTAL: set the maximum
          number of GDB connections that are allowed for the target.
          Default is 1.  A negative value for NUMBER means unlimited
          connections.  See *Note Using GDB as a non-intrusive memory
          inspector: gdbmeminspect.

11.4 Other $target_name Commands
================================

The Tcl/Tk language has the concept of object commands, and OpenOCD
adopts that same model for targets.

A good Tk example is a on screen button.  Once a button is created a
button has a name (a path in Tk terms) and that name is useable as a
first class command.  For example in Tk, one can create a button and
later configure it like this:

     # Create
     button .foobar -background red -command { foo }
     # Modify
     .foobar configure -foreground blue
     # Query
     set x [.foobar cget -background]
     # Report
     puts [format "The button is %s" $x]

In OpenOCD's terms, the "target" is an object just like a Tcl/Tk button,
and its object commands are invoked the same way.

     str912.cpu    mww 0x1234 0x42
     omap3530.cpu  mww 0x5555 123

The commands supported by OpenOCD target objects are:

 -- Command: $target_name arp_examine allow-defer
 -- Command: $target_name arp_halt
 -- Command: $target_name arp_poll
 -- Command: $target_name arp_reset
 -- Command: $target_name arp_waitstate
     Internal OpenOCD scripts (most notably 'startup.tcl') use these to
     deal with specific reset cases.  They are not otherwise documented
     here.

 -- Command: $target_name set_reg dict
     Set register values of the target.

        * DICT ...  Tcl dictionary with pairs of register names and
          values.

     For example, the following command sets the value 0 to the program
     counter (pc) register and 0x1000 to the stack pointer (sp)
     register:

          set_reg {pc 0 sp 0x1000}

 -- Command: $target_name get_reg [-force] list
     Get register values from the target and return them as Tcl
     dictionary with pairs of register names and values.  If option
     "-force" is set, the register values are read directly from the
     target, bypassing any caching.

        * LIST ...  List of register names

     For example, the following command retrieves the values from the
     program counter (pc) and stack pointer (sp) register:

          get_reg {pc sp}

 -- Command: $target_name write_memory address width data ['phys']
     This function provides an efficient way to write to the target
     memory from a Tcl script.

        * ADDRESS ...  target memory address
        * WIDTH ...  memory access bit size, can be 8, 16, 32 or 64
        * DATA ...  Tcl list with the elements to write
        * ['phys'] ...  treat the memory address as physical instead of
          virtual address

     For example, the following command writes two 32 bit words into the
     target memory at address 0x20000000:

          write_memory 0x20000000 32 {0xdeadbeef 0x00230500}

 -- Command: $target_name read_memory address width count ['phys']
     This function provides an efficient way to read the target memory
     from a Tcl script.  A Tcl list containing the requested memory
     elements is returned by this function.

        * ADDRESS ...  target memory address
        * WIDTH ...  memory access bit size, can be 8, 16, 32 or 64
        * COUNT ...  number of elements to read
        * ['phys'] ...  treat the memory address as physical instead of
          virtual address

     For example, the following command reads two 32 bit words from the
     target memory at address 0x20000000:

          read_memory 0x20000000 32 2

 -- Command: $target_name cget queryparm
     Each configuration parameter accepted by '$target_name configure'
     can be individually queried, to return its current value.  The
     QUERYPARM is a parameter name accepted by that command, such as
     '-work-area-phys'.  There are a few special cases:

        * '-event' EVENT_NAME - returns the handler for the event named
          EVENT_NAME.  This is a special case because setting a handler
          requires two parameters.
        * '-type' - returns the target type.  This is a special case
          because this is set using 'target create' and can't be changed
          using '$target_name configure'.

     For example, if you wanted to summarize information about all the
     targets you might use something like this:

          foreach name [target names] {
              set y [$name cget -endian]
              set z [$name cget -type]
              puts [format "Chip %d is %s, Endian: %s, type: %s" \
                           $x $name $y $z]
          }

 -- Command: $target_name curstate
     Displays the current target state: 'debug-running', 'halted',
     'reset', 'running', or 'unknown'.  (Also, *note Event Polling:
     eventpolling.)

 -- Command: $target_name eventlist
     Displays a table listing all event handlers currently associated
     with this target.  *Note Target Events: targetevents.

 -- Command: $target_name invoke-event event_name
     Invokes the handler for the event named EVENT_NAME.  (This is
     primarily intended for use by OpenOCD framework code, for example
     by the reset code in 'startup.tcl'.)

 -- Command: $target_name mdd [phys] addr [count]
 -- Command: $target_name mdw [phys] addr [count]
 -- Command: $target_name mdh [phys] addr [count]
 -- Command: $target_name mdb [phys] addr [count]
     Display contents of address ADDR, as 64-bit doublewords ('mdd'),
     32-bit words ('mdw'), 16-bit halfwords ('mdh'), or 8-bit bytes
     ('mdb').  When the current target has an MMU which is present and
     active, ADDR is interpreted as a virtual address.  Otherwise, or if
     the optional PHYS flag is specified, ADDR is interpreted as a
     physical address.  If COUNT is specified, displays that many units.
     (If you want to process the data instead of displaying it, see the
     'read_memory' primitives.)

 -- Command: $target_name mwd [phys] addr doubleword [count]
 -- Command: $target_name mww [phys] addr word [count]
 -- Command: $target_name mwh [phys] addr halfword [count]
 -- Command: $target_name mwb [phys] addr byte [count]
     Writes the specified DOUBLEWORD (64 bits), WORD (32 bits), HALFWORD
     (16 bits), or BYTE (8-bit) value, at the specified address ADDR.
     When the current target has an MMU which is present and active,
     ADDR is interpreted as a virtual address.  Otherwise, or if the
     optional PHYS flag is specified, ADDR is interpreted as a physical
     address.  If COUNT is specified, fills that many units of
     consecutive address.

11.5 Target Events
==================

At various times, certain things can happen, or you want them to happen.
For example:
   * What should happen when GDB connects?  Should your target reset?
   * When GDB tries to flash the target, do you need to enable the flash
     via a special command?
   * Is using SRST appropriate (and possible) on your system?  Or
     instead of that, do you need to issue JTAG commands to trigger
     reset?  SRST usually resets everything on the scan chain, which can
     be inappropriate.
   * During reset, do you need to write to certain memory locations to
     set up system clocks or to reconfigure the SDRAM? How about
     configuring the watchdog timer, or other peripherals, to stop
     running while you hold the core stopped for debugging?

All of the above items can be addressed by target event handlers.  These
are set up by '$target_name configure -event' or 'target create ...
-event'.

The programmer's model matches the '-command' option used in Tcl/Tk
buttons and events.  The two examples below act the same, but one
creates and invokes a small procedure while the other inlines it.

     proc my_init_proc { } {
         echo "Disabling watchdog..."
         mww 0xfffffd44 0x00008000
     }
     mychip.cpu configure -event reset-init my_init_proc
     mychip.cpu configure -event reset-init {
         echo "Disabling watchdog..."
         mww 0xfffffd44 0x00008000
     }

The following target events are defined:

   * debug-halted
     The target has halted for debug reasons (i.e.: breakpoint)
   * debug-resumed
     The target has resumed (i.e.: GDB said run)
   * early-halted
     Occurs early in the halt process
   * examine-start
     Before target examine is called.
   * examine-end
     After target examine is called with no errors.
   * examine-fail
     After target examine fails.
   * gdb-attach
     When GDB connects.  Issued before any GDB communication with the
     target starts.  GDB expects the target is halted during attachment.
     *Note GDB as a non-intrusive memory inspector: gdbmeminspect, how
     to connect GDB to running target.  The event can be also used to
     set up the target so it is possible to probe flash.  Probing flash
     is necessary during GDB connect if you want to use *note
     programming using GDB: programmingusinggdb.  Another use of the
     flash memory map is for GDB to automatically choose hardware or
     software breakpoints depending on whether the breakpoint is in RAM
     or read only memory.  Default is 'halt'
   * gdb-detach
     When GDB disconnects
   * gdb-end
     When the target has halted and GDB is not doing anything (see early
     halt)
   * gdb-flash-erase-start
     Before the GDB flash process tries to erase the flash (default is
     'reset init')
   * gdb-flash-erase-end
     After the GDB flash process has finished erasing the flash
   * gdb-flash-write-start
     Before GDB writes to the flash
   * gdb-flash-write-end
     After GDB writes to the flash (default is 'reset halt')
   * gdb-start
     Before the target steps, GDB is trying to start/resume the target
   * halted
     The target has halted
   * reset-assert-pre
     Issued as part of 'reset' processing after 'reset-start' was
     triggered but before either SRST alone is asserted on the scan
     chain, or 'reset-assert' is triggered.
   * reset-assert
     Issued as part of 'reset' processing after 'reset-assert-pre' was
     triggered.  When such a handler is present, cores which support
     this event will use it instead of asserting SRST. This support is
     essential for debugging with JTAG interfaces which don't include an
     SRST line (JTAG doesn't require SRST), and for selective reset on
     scan chains that have multiple targets.
   * reset-assert-post
     Issued as part of 'reset' processing after 'reset-assert' has been
     triggered.  or the target asserted SRST on the entire scan chain.
   * reset-deassert-pre
     Issued as part of 'reset' processing after 'reset-assert-post' has
     been triggered.
   * reset-deassert-post
     Issued as part of 'reset' processing after 'reset-deassert-pre' has
     been triggered and (if the target is using it) after SRST has been
     released on the scan chain.
   * reset-end
     Issued as the final step in 'reset' processing.
   * reset-init
     Used by reset init command for board-specific initialization.  This
     event fires after _reset-deassert-post_.

     This is where you would configure PLLs and clocking, set up DRAM so
     you can download programs that don't fit in on-chip SRAM, set up
     pin multiplexing, and so on.  (You may be able to switch to a fast
     JTAG clock rate here, after the target clocks are fully set up.)
   * reset-start
     Issued as the first step in 'reset' processing before
     'reset-assert-pre' is called.

     This is the most robust place to use 'jtag_rclk' or 'adapter speed'
     to switch to a low JTAG clock rate, when reset disables PLLs needed
     to use a fast clock.
   * resume-start
     Before any target is resumed
   * resume-end
     After all targets have resumed
   * resumed
     Target has resumed
   * step-start
     Before a target is single-stepped
   * step-end
     After single-step has completed
   * trace-config
     After target hardware trace configuration was changed
   * semihosting-user-cmd-0x100
     The target made a semihosting call with user-defined operation
     number 0x100
   * semihosting-user-cmd-0x101
     The target made a semihosting call with user-defined operation
     number 0x101
   * semihosting-user-cmd-0x102
     The target made a semihosting call with user-defined operation
     number 0x102
   * semihosting-user-cmd-0x103
     The target made a semihosting call with user-defined operation
     number 0x103
   * semihosting-user-cmd-0x104
     The target made a semihosting call with user-defined operation
     number 0x104
   * semihosting-user-cmd-0x105
     The target made a semihosting call with user-defined operation
     number 0x105
   * semihosting-user-cmd-0x106
     The target made a semihosting call with user-defined operation
     number 0x106
   * semihosting-user-cmd-0x107
     The target made a semihosting call with user-defined operation
     number 0x107

     Note: OpenOCD events are not supposed to be preempt by another
     event, but this is not enforced in current code.  Only the target
     event resumed is executed with polling disabled; this avoids
     polling to trigger the event halted, reversing the logical order of
     execution of their handlers.  Future versions of OpenOCD will
     prevent the event preemption and will disable the schedule of
     polling during the event execution.  Do not rely on polling in any
     event handler; this means, don't expect the status of a core to
     change during the execution of the handler.  The event handler will
     have to enable polling or use '$target_name arp_poll' to check if
     the core has changed status.


File: openocd.info,  Node: Flash Commands,  Next: Flash Programming,  Prev: CPU Configuration,  Up: Top

12 Flash Commands
*****************

OpenOCD has different commands for NOR and NAND flash; the "flash"
command works with NOR flash, while the "nand" command works with NAND
flash.  This partially reflects different hardware technologies: NOR
flash usually supports direct CPU instruction and data bus access, while
data from a NAND flash must be copied to memory before it can be used.
(SPI flash must also be copied to memory before use.)  However, the
documentation also uses "flash" as a generic term; for example, "Put
flash configuration in board-specific files".

Flash Steps:
  1. Configure via the command 'flash bank'
     Do this in a board-specific configuration file, passing parameters
     as needed by the driver.
  2. Operate on the flash via 'flash subcommand'
     Often commands to manipulate the flash are typed by a human, or run
     via a script in some automated way.  Common tasks include writing a
     boot loader, operating system, or other data.
  3. GDB Flashing
     Flashing via GDB requires the flash be configured via "flash bank",
     and the GDB flash features be enabled.  *Note GDB Configuration:
     gdbconfiguration.

Many CPUs have the ability to "boot" from the first flash bank.  This
means that misprogramming that bank can "brick" a system, so that it
can't boot.  JTAG tools, like OpenOCD, are often then used to "de-brick"
the board by (re)installing working boot firmware.

12.1 Flash Configuration Commands
=================================

 -- Config Command: flash bank name driver base size chip_width
          bus_width target [driver_options]
     Configures a flash bank which provides persistent storage for
     addresses from base to base + size - 1.  These banks will often be
     visible to GDB through the target's memory map.  In some cases,
     configuring a flash bank will activate extra commands; see the
     driver-specific documentation.

        * NAME ...  may be used to reference the flash bank in other
          flash commands.  A number is also available.
        * DRIVER ...  identifies the controller driver associated with
          the flash bank being declared.  This is usually 'cfi' for
          external flash, or else the name of a microcontroller with
          embedded flash memory.  *Note Flash Driver List:
          flashdriverlist.
        * BASE ...  Base address of the flash chip.
        * SIZE ...  Size of the chip, in bytes.  For some drivers, this
          value is detected from the hardware.
        * CHIP_WIDTH ...  Width of the flash chip, in bytes; ignored for
          most microcontroller drivers.
        * BUS_WIDTH ...  Width of the data bus used to access the chip,
          in bytes; ignored for most microcontroller drivers.
        * TARGET ...  Names the target used to issue commands to the
          flash controller.
        * DRIVER_OPTIONS ...  drivers may support, or require,
          additional parameters.  See the driver-specific documentation
          for more information.
          Note: This command is not available after OpenOCD
          initialization has completed.  Use it in board specific
          configuration files, not interactively.

 -- Command: flash banks
     Prints a one-line summary of each device that was declared using
     'flash bank', numbered from zero.  Note that this is the _plural_
     form; the _singular_ form is a very different command.

 -- Command: flash list
     Retrieves a list of associative arrays for each device that was
     declared using 'flash bank', numbered from zero.  This returned
     list can be manipulated easily from within scripts.

 -- Command: flash probe num
     Identify the flash, or validate the parameters of the configured
     flash.  Operation depends on the flash type.  The NUM parameter is
     a value shown by 'flash banks'.  Most flash commands will
     implicitly _autoprobe_ the bank; flash drivers can distinguish
     between probing and autoprobing, but most don't bother.

12.2 Preparing a Target before Flash Programming
================================================

The target device should be in well defined state before the flash
programming begins.

_Always issue_ 'reset init' before *note Flash Programming Commands:
flashprogrammingcommands.  Do not issue another 'reset' or 'reset halt'
or 'resume' until the programming session is finished.

If you use *note Programming using GDB: programmingusinggdb, the target
is prepared automatically in the event gdb-flash-erase-start

The jimtcl script 'program' calls 'reset init' explicitly.

12.3 Erasing, Reading, Writing to Flash
=======================================

One feature distinguishing NOR flash from NAND or serial flash
technologies is that for read access, it acts exactly like any other
addressable memory.  This means you can use normal memory read commands
like 'mdw' or 'dump_image' with it, with no special 'flash' subcommands.
*Note Memory access: memoryaccess, and *note Image access: imageaccess.

Write access works differently.  Flash memory normally needs to be
erased before it's written.  Erasing a sector turns all of its bits to
ones, and writing can turn ones into zeroes.  This is why there are
special commands for interactive erasing and writing, and why GDB needs
to know which parts of the address space hold NOR flash memory.

     Note: Most of these erase and write commands leverage the fact that
     NOR flash chips consume target address space.  They implicitly
     refer to the current JTAG target, and map from an address in that
     target's address space back to a flash bank.  A few commands use
     abstract addressing based on bank and sector numbers, and don't
     depend on searching the current target and its address space.
     Avoid confusing the two command models.

Some flash chips implement software protection against accidental
writes, since such buggy writes could in some cases "brick" a system.
For such systems, erasing and writing may require sector protection to
be disabled first.  Examples include CFI flash such as "Intel Advanced
Bootblock flash", and AT91SAM7 on-chip flash.  *Note flash protect:
flashprotect.

 -- Command: flash erase_sector num first last
     Erase sectors in bank NUM, starting at sector FIRST up to and
     including LAST.  Sector numbering starts at 0.  Providing a LAST
     sector of 'last' specifies "to the end of the flash bank".  The NUM
     parameter is a value shown by 'flash banks'.

 -- Command: flash erase_address [pad] [unlock] address length
     Erase sectors starting at ADDRESS for LENGTH bytes.  Unless 'pad'
     is specified, address must begin a flash sector, and address +
     length - 1 must end a sector.  Specifying 'pad' erases extra data
     at the beginning and/or end of the specified region, as needed to
     erase only full sectors.  The flash bank to use is inferred from
     the ADDRESS, and the specified length must stay within that bank.
     As a special case, when LENGTH is zero and ADDRESS is the start of
     the bank, the whole flash is erased.  If 'unlock' is specified,
     then the flash is unprotected before erase starts.

 -- Command: flash filld address double-word length
 -- Command: flash fillw address word length
 -- Command: flash fillh address halfword length
 -- Command: flash fillb address byte length
     Fills flash memory with the specified DOUBLE-WORD (64 bits), WORD
     (32 bits), HALFWORD (16 bits), or BYTE (8-bit) pattern, starting at
     ADDRESS and continuing for LENGTH units (word/halfword/byte).  No
     erasure is done before writing; when needed, that must be done
     before issuing this command.  Writes are done in blocks of up to
     1024 bytes, and each write is verified by reading back the data and
     comparing it to what was written.  The flash bank to use is
     inferred from the ADDRESS of each block, and the specified length
     must stay within that bank.

 -- Command: flash mdw addr [count]
 -- Command: flash mdh addr [count]
 -- Command: flash mdb addr [count]
     Display contents of address ADDR, as 32-bit words ('mdw'), 16-bit
     halfwords ('mdh'), or 8-bit bytes ('mdb').  If COUNT is specified,
     displays that many units.  Reads from flash using the flash driver,
     therefore it enables reading from a bank not mapped in target
     address space.  The flash bank to use is inferred from the ADDRESS
     of each block, and the specified length must stay within that bank.

 -- Command: flash write_bank num filename [offset]
     Write the binary 'filename' to flash bank NUM, starting at OFFSET
     bytes from the beginning of the bank.  If OFFSET is omitted, start
     at the beginning of the flash bank.  The NUM parameter is a value
     shown by 'flash banks'.

 -- Command: flash read_bank num filename [offset [length]]
     Read LENGTH bytes from the flash bank NUM starting at OFFSET and
     write the contents to the binary 'filename'.  If OFFSET is omitted,
     start at the beginning of the flash bank.  If LENGTH is omitted,
     read the remaining bytes from the flash bank.  The NUM parameter is
     a value shown by 'flash banks'.

 -- Command: flash verify_bank num filename [offset]
     Compare the contents of the binary file FILENAME with the contents
     of the flash bank NUM starting at OFFSET.  If OFFSET is omitted,
     start at the beginning of the flash bank.  Fail if the contents do
     not match.  The NUM parameter is a value shown by 'flash banks'.

 -- Command: flash write_image [erase] [unlock] filename [offset] [type]
     Write the image 'filename' to the current target's flash bank(s).
     Only loadable sections from the image are written.  A relocation
     OFFSET may be specified, in which case it is added to the base
     address for each section in the image.  The file [TYPE] can be
     specified explicitly as 'bin' (binary), 'ihex' (Intel hex), 'elf'
     (ELF file), 's19' (Motorola s19).  'mem', or 'builder'.  The
     relevant flash sectors will be erased prior to programming if the
     'erase' parameter is given.  If 'unlock' is provided, then the
     flash banks are unlocked before erase and program.  The flash bank
     to use is inferred from the address of each image section.

          Warning: Be careful using the 'erase' flag when the flash is
          holding data you want to preserve.  Portions of the flash
          outside those described in the image's sections might be
          erased with no notice.
             * When a section of the image being written does not fill
               out all the sectors it uses, the unwritten parts of those
               sectors are necessarily also erased, because sectors
               can't be partially erased.
             * Data stored in sector "holes" between image sections are
               also affected.  For example, "'flash write_image erase
               ...'" of an image with one byte at the beginning of a
               flash bank and one byte at the end erases the entire bank
               - not just the two sectors being written.
          Also, when flash protection is important, you must re-apply it
          after it has been removed by the 'unlock' flag.

 -- Command: flash verify_image filename [offset] [type]
     Verify the image 'filename' to the current target's flash bank(s).
     Parameters follow the description of 'flash write_image'.  In
     contrast to the 'verify_image' command, for banks with specific
     verify method, that one is used instead of the usual target's read
     memory methods.  This is necessary for flash banks not readable by
     ordinary memory reads.  This command gives only an overall good/bad
     result for each bank, not addresses of individual failed bytes as
     it's intended only as quick check for successful programming.

12.4 Other Flash commands
=========================

 -- Command: flash erase_check num
     Check erase state of sectors in flash bank NUM, and display that
     status.  The NUM parameter is a value shown by 'flash banks'.

 -- Command: flash info num [sectors]
     Print info about flash bank NUM, a list of protection blocks and
     their status.  Use 'sectors' to show a list of sectors instead.

     The NUM parameter is a value shown by 'flash banks'.  This command
     will first query the hardware, it does not print cached and
     possibly stale information.

 -- Command: flash protect num first last (on|off)
     Enable ('on') or disable ('off') protection of flash blocks in
     flash bank NUM, starting at protection block FIRST and continuing
     up to and including LAST.  Providing a LAST block of 'last'
     specifies "to the end of the flash bank".  The NUM parameter is a
     value shown by 'flash banks'.  The protection block is usually
     identical to a flash sector.  Some devices may utilize a protection
     block distinct from flash sector.  See 'flash info' for a list of
     protection blocks.

 -- Command: flash padded_value num value
     Sets the default value used for padding any image sections, This
     should normally match the flash bank erased value.  If not
     specified by this command or the flash driver then it defaults to
     0xff.

 -- Command: program filename [preverify] [verify] [reset] [exit]
          [offset]
     This is a helper script that simplifies using OpenOCD as a
     standalone programmer.  The only required parameter is 'filename',
     the others are optional.  *Note Flash Programming::.

12.5 Flash Driver List
======================

As noted above, the 'flash bank' command requires a driver name, and
allows driver-specific options and behaviors.  Some drivers also
activate driver-specific commands.

 -- Flash Driver: virtual
     This is a special driver that maps a previously defined bank to
     another address.  All bank settings will be copied from the master
     physical bank.

     The VIRTUAL driver defines one mandatory parameters,

        * MASTER_BANK The bank that this virtual address refers to.

     So in the following example addresses 0xbfc00000 and 0x9fc00000
     refer to the flash bank defined at address 0x1fc00000.  Any command
     executed on the virtual banks is actually performed on the physical
     banks.
          flash bank $_FLASHNAME pic32mx 0x1fc00000 0 0 0 $_TARGETNAME
          flash bank vbank0 virtual 0xbfc00000 0 0 0 \
                     $_TARGETNAME $_FLASHNAME
          flash bank vbank1 virtual 0x9fc00000 0 0 0 \
                     $_TARGETNAME $_FLASHNAME

12.5.1 External Flash
---------------------

 -- Flash Driver: cfi
     The "Common Flash Interface" (CFI) is the main standard for
     external NOR flash chips, each of which connects to a specific
     external chip select on the CPU. Frequently the first such chip is
     used to boot the system.  Your board's 'reset-init' handler might
     need to configure additional chip selects using other commands
     (like: 'mww' to configure a bus and its timings), or perhaps
     configure a GPIO pin that controls the "write protect" pin on the
     flash chip.  The CFI driver can use a target-specific working area
     to significantly speed up operation.

     The CFI driver can accept the following optional parameters, in any
     order:

        * JEDEC_PROBE ...  is used to detect certain non-CFI flash ROMs,
          like AM29LV010 and similar types.
        * X16_AS_X8 ...  when a 16-bit flash is hooked up to an 8-bit
          bus.
        * BUS_SWAP ...  when data bytes in a 16-bit flash needs to be
          swapped.
        * DATA_SWAP ...  when data bytes in a 16-bit flash needs to be
          swapped when writing data values (i.e.  not CFI commands).

     To configure two adjacent banks of 16 MBytes each, both sixteen
     bits (two bytes) wide on a sixteen bit bus:

          flash bank $_FLASHNAME cfi 0x00000000 0x01000000 2 2 $_TARGETNAME
          flash bank $_FLASHNAME cfi 0x01000000 0x01000000 2 2 $_TARGETNAME

     To configure one bank of 32 MBytes built from two sixteen bit (two
     byte) wide parts wired in parallel to create a thirty-two bit (four
     byte) bus with doubled throughput:

          flash bank $_FLASHNAME cfi 0x00000000 0x02000000 2 4 $_TARGETNAME

 -- Flash Driver: jtagspi
     Several FPGAs and CPLDs can retrieve their configuration
     (bitstream) from a SPI flash connected to them.  To access this
     flash from the host, the device is first programmed with a special
     proxy bitstream that exposes the SPI flash on the device's JTAG
     interface.  The flash can then be accessed through JTAG.

     Since signaling between JTAG and SPI is compatible, all that is
     required for a proxy bitstream is to connect TDI-MOSI, TDO-MISO,
     TCK-CLK and activate the flash chip select when the JTAG state
     machine is in SHIFT-DR. Such a bitstream for several Xilinx FPGAs
     can be found in 'contrib/loaders/flash/fpga/xilinx_bscan_spi.py'.
     It requires migen (https://github.com/m-labs/migen) and a Xilinx
     toolchain to build.

     This flash bank driver requires a target on a JTAG tap and will
     access that tap directly.  Since no support from the target is
     needed, the target can be a "testee" dummy.  Since the target does
     not expose the flash memory mapping, target commands that would
     otherwise be expected to access the flash will not work.  These
     include all '*_image' and '$target_name m*' commands as well as
     'program'.  Equivalent functionality is available through the
     'flash write_bank', 'flash read_bank', and 'flash verify_bank'
     commands.

     According to device size, 1- to 4-byte addresses are sent.
     However, some flash chips additionally have to be switched to
     4-byte addresses by an extra command, see below.

        * IR ...  is loaded into the JTAG IR to map the flash as the
          JTAG DR. For the bitstreams generated from
          'xilinx_bscan_spi.py' this is the USER1 instruction.

          target create $_TARGETNAME testee -chain-position $_CHIPNAME.fpga
          set _XILINX_USER1 0x02
          flash bank $_FLASHNAME spi 0x0 0 0 0 \
                     $_TARGETNAME $_XILINX_USER1

      -- Command: jtagspi set bank_id name total_size page_size read_cmd
               unused pprg_cmd mass_erase_cmd sector_size
               sector_erase_cmd
          Sets flash parameters: NAME human readable string, TOTAL_SIZE
          size in bytes, PAGE_SIZE is write page size.  READ_CMD and
          PPRG_CMD are commands for read and page program, respectively.
          MASS_ERASE_CMD, SECTOR_SIZE and SECTOR_ERASE_CMD are optional.
               jtagspi set 0 w25q128 0x1000000 0x100 0x03 0 0x02 0xC7 0x10000 0xD8

      -- Command: jtagspi cmd bank_id resp_num cmd_byte ...
          Sends command CMD_BYTE and at most 20 following bytes and
          reads RESP_NUM bytes afterwards.  E.g.  for 'Enter 4-byte
          address mode'
               jtagspi cmd 0 0 0xB7

      -- Command: jtagspi always_4byte bank_id [ on | off ]
          Some devices use 4-byte addresses for all commands except the
          legacy 0x03 read regardless of device size.  This command
          controls the corresponding hack.

 -- Flash Driver: xcf
     Xilinx FPGAs can be configured from specialized flash ICs named
     Platform Flash.  It is (almost) regular NOR flash with erase
     sectors, program pages, etc.  The only difference is special
     registers controlling its FPGA specific behavior.  They must be
     properly configured for successful FPGA loading using additional
     XCF driver command:

      -- Command: xcf ccb <bank_id>
          command accepts additional parameters:
             * EXTERNAL|INTERNAL ...  selects clock source.
             * SERIAL|PARALLEL ...  selects serial or parallel data bus
               mode.
             * SLAVE|MASTER ...  selects slave of master mode for flash
               device.
             * 40|20 ...  selects clock frequency in MHz for internal
               clock in master mode.
               xcf ccb 0 external parallel slave 40
          All of them must be specified even if clock frequency is
          pointless in slave mode.  If only bank id specified than
          command prints current CCB register value.  Note: there is no
          need to write this register every time you erase/program data
          sectors because it stores in dedicated sector.

      -- Command: xcf configure <bank_id>
          Initiates FPGA loading procedure.  Useful if your board has no
          "configure" button.
               xcf configure 0

     Additional driver notes:
        * Only single revision supported.
        * Driver automatically detects need of bit reverse, but only
          "bin" (raw binary, do not confuse it with "bit") and "mcs"
          (Intel hex) file types supported.
        * For additional info check xapp972.pdf and ug380.pdf.

 -- Flash Driver: lpcspifi
     NXP's LPC43xx and LPC18xx families include a proprietary SPI Flash
     Interface (SPIFI) peripheral that can drive and provide memory
     mapped access to external SPI flash devices.

     The lpcspifi driver initializes this interface and provides program
     and erase functionality for these serial flash devices.  Use of
     this driver requires a working area of at least 1kB to be
     configured on the target device; more than this will significantly
     reduce flash programming times.

     The setup command only requires the BASE parameter.  All other
     parameters are ignored, and the flash size and layout are
     configured by the driver.

          flash bank $_FLASHNAME lpcspifi 0x14000000 0 0 0 $_TARGETNAME

 -- Flash Driver: stmsmi
     Some devices from STMicroelectronics (e.g.  STR75x MCU family,
     SPEAr MPU family) include a proprietary "Serial Memory Interface"
     (SMI) controller able to drive external SPI flash devices.
     Depending on specific device and board configuration, up to 4
     external flash devices can be connected.

     SMI makes the flash content directly accessible in the CPU address
     space; each external device is mapped in a memory bank.  CPU can
     directly read data, execute code and boot from SMI banks.  Normal
     OpenOCD commands like 'mdw' can be used to display the flash
     content.

     The setup command only requires the BASE parameter in order to
     identify the memory bank.  All other parameters are ignored.
     Additional information, like flash size, are detected
     automatically.

          flash bank $_FLASHNAME stmsmi 0xf8000000 0 0 0 $_TARGETNAME

 -- Flash Driver: stmqspi
     Some devices from STMicroelectronics include a proprietary "QuadSPI
     Interface" (e.g.  STM32F4, STM32F7, STM32L4) or "OctoSPI Interface"
     (e.g.  STM32L4+) controller able to drive one or even two (dual
     mode) external SPI flash devices.  The OctoSPI is a superset of
     QuadSPI, its presence is detected automatically.  Currently only
     the regular command mode is supported, whereas the HyperFlash mode
     is not.

     QuadSPI/OctoSPI makes the flash contents directly accessible in the
     CPU address space; in case of dual mode both devices must be of the
     same type and are mapped in the same memory bank (even and odd
     addresses interleaved).  CPU can directly read data, execute code
     (but not boot) from QuadSPI bank.

     The 'flash bank' command only requires the BASE parameter and the
     extra parameter IO_BASE in order to identify the memory bank.  Both
     are fixed by hardware, see datasheet or RM. All other parameters
     are ignored.

     The controller must be initialized after each reset and properly
     configured for memory-mapped read operation for the particular
     flash chip(s), for the full list of available register settings cf.
     the controller's RM. This setup is quite board specific (that's why
     booting from this memory is not possible).  The flash driver infers
     all parameters from current controller register values when 'flash
     probe BANK_ID' is executed.

     Normal OpenOCD commands like 'mdw' can be used to display the flash
     content, but only after proper controller initialization as
     described above.  However, due to a silicon bug in some devices,
     attempting to access the very last word should be avoided.

     It is possible to use two (even different) flash chips
     alternatingly, if individual bank chip selects are available.  For
     some package variants, this is not the case due to limited pin
     count.  To switch from one to another, adjust FSEL bit accordingly
     and re-issue 'flash probe bank_id'.  Note that the bank base
     address will _not_ change, so the address spaces of both devices
     will overlap.  In dual flash mode both chips must be identical
     regarding size and most other properties.

     Block or sector protection internal to the flash chip is not
     handled by this driver at all, but can be dealt with manually by
     the 'cmd' command, see below.  The sector protection via 'flash
     protect' command etc.  is completely internal to openocd, intended
     only to prevent accidental erase or overwrite and it does not
     persist across openocd invocations.

     OpenOCD contains a hardcoded list of flash devices with their
     properties, these are auto-detected.  If a device is not included
     in this list, SFDP discovery is attempted.  If this fails or gives
     inappropriate results, manual setting is required (see 'set'
     command).

          flash bank $_FLASHNAME stmqspi 0x90000000 0 0 0 \
                     $_TARGETNAME 0xA0001000
          flash bank $_FLASHNAME stmqspi 0x70000000 0 0 0 \
                     $_TARGETNAME 0xA0001400

     There are three specific commands
      -- Command: stmqspi mass_erase bank_id
          Clears sector protections and performs a mass erase.  Works
          only if there is no chip specific write protection engaged.

      -- Command: stmqspi set bank_id name total_size page_size read_cmd
               fread_cmd pprg_cmd mass_erase_cmd sector_size
               sector_erase_cmd
          Set flash parameters: NAME human readable string, TOTAL_SIZE
          size in bytes, PAGE_SIZE is write page size.  READ_CMD,
          FREAD_CMD and PPRG_CMD are commands for reading and page
          programming.  FREAD_CMD is used in DPI and QPI modes, READ_CMD
          in normal SPI (single line) mode.  MASS_ERASE_CMD, SECTOR_SIZE
          and SECTOR_ERASE_CMD are optional.

          This command is required if chip id is not hardcoded yet and
          e.g.  for EEPROMs or FRAMs which don't support an id command.

          In dual mode parameters of both chips are set identically.
          The parameters refer to a single chip, so the whole bank gets
          twice the specified capacity etc.

      -- Command: stmqspi cmd bank_id resp_num cmd_byte ...
          If RESP_NUM is zero, sends command CMD_BYTE and following data
          bytes.  In dual mode command byte is sent to _both_ chips but
          data bytes are sent _alternatingly_ to chip 1 and 2, first to
          flash 1, second to flash 2, etc., i.e.  the total number of
          bytes (including cmd_byte) must be odd.

          If RESP_NUM is not zero, cmd and at most four following data
          bytes are sent, in dual mode _simultaneously_ to both chips.
          Then RESP_NUM bytes are read interleaved from both chips
          starting with chip 1.  In this case RESP_NUM must be even.

          Note the hardware dictated subtle difference of those two
          cases in dual-flash mode.

          To check basic communication settings, issue
               stmqspi cmd bank_id 0 0x04; stmqspi cmd bank_id 1 0x05
               stmqspi cmd bank_id 0 0x06; stmqspi cmd bank_id 1 0x05
          for single flash mode or
               stmqspi cmd bank_id 0 0x04; stmqspi cmd bank_id 2 0x05
               stmqspi cmd bank_id 0 0x06; stmqspi cmd bank_id 2 0x05
          for dual flash mode.  This should return the status register
          contents.

          In 8-line mode, CMD_BYTE is sent twice - first time as given,
          second time complemented.  Additionally, in 8-line mode only,
          some commands (e.g.  Read Status) need a dummy address, e.g.
               stmqspi cmd bank_id 1 0x05 0x00 0x00 0x00 0x00
          should return the status register contents.

 -- Flash Driver: mrvlqspi
     This driver supports QSPI flash controller of Marvell's Wireless
     Microcontroller platform.

     The flash size is autodetected based on the table of known JEDEC
     IDs hardcoded in the OpenOCD sources.

          flash bank $_FLASHNAME mrvlqspi 0x0 0 0 0 $_TARGETNAME 0x46010000

 -- Flash Driver: ath79
     Members of ATH79 SoC family from Atheros include a SPI interface
     with 3 chip selects.  On reset a SPI flash connected to the first
     chip select (CS0) is made directly read-accessible in the CPU
     address space (up to 16MBytes) and is usually used to store the
     bootloader and operating system.  Normal OpenOCD commands like
     'mdw' can be used to display the flash content while it is in
     memory-mapped mode (only the first 4MBytes are accessible without
     additional configuration on reset).

     The setup command only requires the BASE parameter in order to
     identify the memory bank.  The actual value for the base address is
     not otherwise used by the driver.  However the mapping is passed to
     gdb.  Thus for the memory mapped flash (chipselect CS0) the base
     address should be the actual memory mapped base address.  For
     unmapped chipselects (CS1 and CS2) care should be taken to use a
     base address that does not overlap with real memory regions.
     Additional information, like flash size, are detected
     automatically.  An optional additional parameter sets the
     chipselect for the bank, with the default CS0.  CS1 and CS2 require
     additional GPIO setup before they can be used since the alternate
     function must be enabled on the GPIO pin CS1/CS2 is routed to on
     the given SoC.

          flash bank $_FLASHNAME ath79 0xbf000000 0 0 0 $_TARGETNAME

          # When using multiple chipselects the base should be different
          # for each, otherwise the write_image command is not able to
          # distinguish the banks.
          flash bank flash0 ath79 0xbf000000 0 0 0 $_TARGETNAME cs0
          flash bank flash1 ath79 0x10000000 0 0 0 $_TARGETNAME cs1
          flash bank flash2 ath79 0x20000000 0 0 0 $_TARGETNAME cs2

 -- Flash Driver: fespi

     SiFive's Freedom E SPI controller, used in HiFive and other boards.

          flash bank $_FLASHNAME fespi 0x20000000 0 0 0 $_TARGETNAME

12.5.2 Internal Flash (Microcontrollers)
----------------------------------------

 -- Flash Driver: aduc702x
     The ADUC702x analog microcontrollers from Analog Devices include
     internal flash and use ARM7TDMI cores.  The aduc702x flash driver
     works with models ADUC7019 through ADUC7028.  The setup command
     only requires the TARGET argument since all devices in this family
     have the same memory layout.

          flash bank $_FLASHNAME aduc702x 0 0 0 0 $_TARGETNAME

 -- Flash Driver: ambiqmicro
     All members of the Apollo microcontroller family from Ambiq Micro
     include internal flash and use ARM's Cortex-M4 core.  The host
     connects over USB to an FTDI interface that communicates with the
     target using SWD.

     The AMBIQMICRO driver reads the Chip Information Register detect
     the device class of the MCU. The Flash and SRAM sizes directly
     follow device class, and are used to set up the flash banks.  If
     this fails, the driver will use default values set to the minimum
     sizes of an Apollo chip.

     All Apollo chips have two flash banks of the same size.  In all
     cases the first flash bank starts at location 0, and the second
     bank starts after the first.

          # Flash bank 0
          flash bank $_FLASHNAME ambiqmicro 0 0x00040000 0 0 $_TARGETNAME
          # Flash bank 1 - same size as bank0, starts after bank 0.
          flash bank $_FLASHNAME ambiqmicro 0x00040000 0x00040000 0 0 \
                     $_TARGETNAME

     Flash is programmed using custom entry points into the bootloader.
     This is the only way to program the flash as no flash control
     registers are available to the user.

     The AMBIQMICRO driver adds some additional commands:

      -- Command: ambiqmicro mass_erase <bank>
          Erase entire bank.
      -- Command: ambiqmicro page_erase <bank> <first> <last>
          Erase device pages.
      -- Command: ambiqmicro program_otp <bank> <offset> <count>
          Program OTP is a one time operation to create write protected
          flash.  The user writes sectors to SRAM starting at
          0x10000010.  Program OTP will write these sectors from SRAM to
          flash, and write protect the flash.

 -- Flash Driver: at91samd
     All members of the ATSAM D2x, D1x, D0x, ATSAMR, ATSAML and ATSAMC
     microcontroller families from Atmel include internal flash and use
     ARM's Cortex-M0+ core.

     Do not use for ATSAM D51 and E5x: use *Note atsame5::.

     The devices have one flash bank:

          flash bank $_FLASHNAME at91samd 0x00000000 0 1 1 $_TARGETNAME

      -- Command: at91samd chip-erase
          Issues a complete Flash erase via the Device Service Unit
          (DSU). This can be used to erase a chip back to its factory
          state and does not require the processor to be halted.

      -- Command: at91samd set-security
          Secures the Flash via the Set Security Bit (SSB) command.
          This prevents access to the Flash and can only be undone by
          using the chip-erase command which erases the Flash contents
          and turns off the security bit.  Warning: at this time,
          openocd will not be able to communicate with a secured chip
          and it is therefore not possible to chip-erase it without
          using another tool.

               at91samd set-security enable

      -- Command: at91samd eeprom
          Shows or sets the EEPROM emulation size configuration, stored
          in the User Row of the Flash.  When setting, the EEPROM size
          must be specified in bytes and it must be one of the permitted
          sizes according to the datasheet.  Settings are written
          immediately but only take effect on MCU reset.  EEPROM
          emulation requires additional firmware support and the minimum
          EEPROM size may not be the same as the minimum that the
          hardware supports.  Set the EEPROM size to 0 in order to
          disable this feature.

               at91samd eeprom
               at91samd eeprom 1024

      -- Command: at91samd bootloader
          Shows or sets the bootloader size configuration, stored in the
          User Row of the Flash.  This is called the BOOTPROT region.
          When setting, the bootloader size must be specified in bytes
          and it must be one of the permitted sizes according to the
          datasheet.  Settings are written immediately but only take
          effect on MCU reset.  Setting the bootloader size to 0
          disables bootloader protection.

               at91samd bootloader
               at91samd bootloader 16384

      -- Command: at91samd dsu_reset_deassert
          This command releases internal reset held by DSU and prepares
          reset vector catch in case of reset halt.  Command is used
          internally in event reset-deassert-post.

      -- Command: at91samd nvmuserrow
          Writes or reads the entire 64 bit wide NVM user row register
          which is located at 0x804000.  This register includes various
          fuses lock-bits and factory calibration data.  Reading the
          register is done by invoking this command without any
          arguments.  Writing is possible by giving 1 or 2 hex values.
          The first argument is the register value to be written and the
          second one is an optional changemask.  Every bit which value
          in changemask is 0 will stay unchanged.  The lock- and
          reserved-bits are masked out and cannot be changed.

               # Read user row
               >at91samd nvmuserrow
               NVMUSERROW: 0xFFFFFC5DD8E0C788
               # Write 0xFFFFFC5DD8E0C788 to user row
               >at91samd nvmuserrow 0xFFFFFC5DD8E0C788
               # Write 0x12300 to user row but leave other bits and low
               # byte unchanged
               >at91samd nvmuserrow 0x12345 0xFFF00

 -- Flash Driver: at91sam3
     All members of the AT91SAM3 microcontroller family from Atmel
     include internal flash and use ARM's Cortex-M3 core.  The driver
     currently (6/22/09) recognizes the AT91SAM3U[1/2/4][C/E] chips.
     Note that the driver was orginaly developed and tested using the
     AT91SAM3U4E, using a SAM3U-EK eval board.  Support for other chips
     in the family was cribbed from the data sheet.  _Note to future
     readers/updaters: Please remove this worrisome comment after other
     chips are confirmed._

     The AT91SAM3U4[E/C] (256K) chips have two flash banks; most other
     chips have one flash bank.  In all cases the flash banks are at the
     following fixed locations:

          # Flash bank 0 - all chips
          flash bank $_FLASHNAME at91sam3 0x00080000 0 1 1 $_TARGETNAME
          # Flash bank 1 - only 256K chips
          flash bank $_FLASHNAME at91sam3 0x00100000 0 1 1 $_TARGETNAME

     Internally, the AT91SAM3 flash memory is organized as follows.
     Unlike the AT91SAM7 chips, these are not used as parameters to the
     'flash bank' command:

        * _N-Banks:_ 256K chips have 2 banks, others have 1 bank.
        * _Bank Size:_ 128K/64K Per flash bank
        * _Sectors:_ 16 or 8 per bank
        * _SectorSize:_ 8K Per Sector
        * _PageSize:_ 256 bytes per page.  Note that OpenOCD operates on
          'sector' sizes, not page sizes.

     The AT91SAM3 driver adds some additional commands:

      -- Command: at91sam3 gpnvm
      -- Command: at91sam3 gpnvm clear number
      -- Command: at91sam3 gpnvm set number
      -- Command: at91sam3 gpnvm show [all|number]
          With no parameters, 'show' or 'show all', shows the status of
          all GPNVM bits.  With 'show' NUMBER, displays that bit.

          With 'set' NUMBER or 'clear' NUMBER, modifies that GPNVM bit.

      -- Command: at91sam3 info
          This command attempts to display information about the
          AT91SAM3 chip.  _First_ it read the 'CHIPID_CIDR' [address
          0x400e0740, see Section 28.2.1, page 505 of the AT91SAM3U
          29/may/2009 datasheet, document id: doc6430A] and decodes the
          values.  _Second_ it reads the various clock configuration
          registers and attempts to display how it believes the chip is
          configured.  By default, the SLOWCLK is assumed to be 32768
          Hz, see the command 'at91sam3 slowclk'.

      -- Command: at91sam3 slowclk [value]
          This command shows/sets the slow clock frequency used in the
          'at91sam3 info' command calculations above.

 -- Flash Driver: at91sam4
     All members of the AT91SAM4 microcontroller family from Atmel
     include internal flash and use ARM's Cortex-M4 core.  This driver
     uses the same command names/syntax as *Note at91sam3::.

 -- Flash Driver: at91sam4l
     All members of the AT91SAM4L microcontroller family from Atmel
     include internal flash and use ARM's Cortex-M4 core.  This driver
     uses the same command names/syntax as *Note at91sam3::.

     The AT91SAM4L driver adds some additional commands:
      -- Command: at91sam4l smap_reset_deassert
          This command releases internal reset held by SMAP and prepares
          reset vector catch in case of reset halt.  Command is used
          internally in event reset-deassert-post.

 -- Flash Driver: atsame5
     All members of the SAM E54, E53, E51 and D51 microcontroller
     families from Microchip (former Atmel) include internal flash and
     use ARM's Cortex-M4 core.

     The devices have two ECC flash banks with a swapping feature.  This
     driver handles both banks together as it were one.  Bank swapping
     is not supported yet.

          flash bank $_FLASHNAME atsame5 0x00000000 0 1 1 $_TARGETNAME

      -- Command: atsame5 bootloader
          Shows or sets the bootloader size configuration, stored in the
          User Page of the Flash.  This is called the BOOTPROT region.
          When setting, the bootloader size must be specified in bytes.
          The nearest bigger protection size is used.  Settings are
          written immediately but only take effect on MCU reset.
          Setting the bootloader size to 0 disables bootloader
          protection.

               atsame5 bootloader
               atsame5 bootloader 16384

      -- Command: atsame5 chip-erase
          Issues a complete Flash erase via the Device Service Unit
          (DSU). This can be used to erase a chip back to its factory
          state and does not require the processor to be halted.

      -- Command: atsame5 dsu_reset_deassert
          This command releases internal reset held by DSU and prepares
          reset vector catch in case of reset halt.  Command is used
          internally in event reset-deassert-post.

      -- Command: atsame5 userpage
          Writes or reads the first 64 bits of NVM User Page which is
          located at 0x804000.  This field includes various fuses.
          Reading is done by invoking this command without any
          arguments.  Writing is possible by giving 1 or 2 hex values.
          The first argument is the value to be written and the second
          one is an optional bit mask (a zero bit in the mask means the
          bit stays unchanged).  The reserved fields are always masked
          out and cannot be changed.

               # Read
               >atsame5 userpage
               USER PAGE: 0xAEECFF80FE9A9239
               # Write
               >atsame5 userpage 0xAEECFF80FE9A9239
               # Write 2 to SEESBLK and 4 to SEEPSZ fields but leave other
               # bits unchanged (setup SmartEEPROM of virtual size 8192
               # bytes)
               >atsame5 userpage 0x4200000000 0x7f00000000

 -- Flash Driver: atsamv
     All members of the ATSAMV7x, ATSAMS70, and ATSAME70 families from
     Atmel include internal flash and use ARM's Cortex-M7 core.  This
     driver uses the same command names/syntax as *Note at91sam3::.

          flash bank $_FLASHNAME atsamv 0x00400000 0 0 0 $_TARGETNAME

      -- Command: atsamv gpnvm [show [all|number]]
      -- Command: atsamv gpnvm (clr|set) number
          With no parameters, 'show' or 'show all', shows the status of
          all GPNVM bits.  With 'show' NUMBER, displays that bit.

          With 'set' NUMBER or 'clear' NUMBER, modifies that GPNVM bit.

 -- Flash Driver: at91sam7
     All members of the AT91SAM7 microcontroller family from Atmel
     include internal flash and use ARM7TDMI cores.  The driver
     automatically recognizes a number of these chips using the chip
     identification register, and autoconfigures itself.

          flash bank $_FLASHNAME at91sam7 0 0 0 0 $_TARGETNAME

     For chips which are not recognized by the controller driver, you
     must provide additional parameters in the following order:

        * CHIP_MODEL ...  label used with 'flash info'
        * BANKS
        * SECTORS_PER_BANK
        * PAGES_PER_SECTOR
        * PAGES_SIZE
        * NUM_NVM_BITS
        * FREQ_KHZ ...  required if an external clock is provided,
          optional (but recommended) when the oscillator frequency is
          known

     It is recommended that you provide zeroes for all of those values
     except the clock frequency, so that everything except that
     frequency will be autoconfigured.  Knowing the frequency helps
     ensure correct timings for flash access.

     The flash controller handles erases automatically on a page
     (128/256 byte) basis, so explicit erase commands are not necessary
     for flash programming.  However, there is an "EraseAll" command
     that can erase an entire flash plane (of up to 256KB), and it will
     be used automatically when you issue 'flash erase_sector' or 'flash
     erase_address' commands.

      -- Command: at91sam7 gpnvm bitnum (set|clear)
          Set or clear a "General Purpose Non-Volatile Memory" (GPNVM)
          bit for the processor.  Each processor has a number of such
          bits, used for controlling features such as brownout detection
          (so they are not truly general purpose).
               Note: This assumes that the first flash bank (number 0)
               is associated with the appropriate at91sam7 target.

 -- Flash Driver: avr
     The AVR 8-bit microcontrollers from Atmel integrate flash memory.
     _The current implementation is incomplete._

 -- Flash Driver: bluenrg-x
     STMicroelectronics BlueNRG-1, BlueNRG-2 and BlueNRG-LP Bluetooth
     low energy wireless system-on-chip.  They include ARM Cortex-M0/M0+
     core and internal flash memory.  The driver automatically
     recognizes these chips using the chip identification registers, and
     autoconfigures itself.

          flash bank $_FLASHNAME bluenrg-x 0 0 0 0 $_TARGETNAME

     Note that when users ask to erase all the sectors of the flash, a
     mass erase command is used which is faster than erasing each single
     sector one by one.

          flash erase_sector 0 0 last # It will perform a mass erase

     Triggering a mass erase is also useful when users want to disable
     readout protection.

 -- Flash Driver: cc26xx
     All versions of the SimpleLink CC13xx and CC26xx microcontrollers
     from Texas Instruments include internal flash.  The cc26xx flash
     driver supports both the CC13xx and CC26xx family of devices.  The
     driver automatically recognizes the specific version's flash
     parameters and autoconfigures itself.  The flash bank starts at
     address 0.

          flash bank $_FLASHNAME cc26xx 0 0 0 0 $_TARGETNAME

 -- Flash Driver: cc3220sf
     The CC3220SF version of the SimpleLink CC32xx microcontrollers from
     Texas Instruments includes 1MB of internal flash.  The cc3220sf
     flash driver only supports the internal flash.  The serial flash on
     SimpleLink boards is programmed via the bootloader over a UART
     connection.  Security features of the CC3220SF may erase the
     internal flash during power on reset.  Refer to documentation at
     <www.ti.com/cc3220sf> for details on security features and
     programming the serial flash.

          flash bank $_FLASHNAME cc3220sf 0 0 0 0 $_TARGETNAME

 -- Flash Driver: efm32
     All members of the EFM32/EFR32 microcontroller family from Energy
     Micro (now Silicon Labs) include internal flash and use Arm
     Cortex-M3 or Cortex-M4 cores.  The driver automatically recognizes
     a number of these chips using the chip identification register, and
     autoconfigures itself.
          flash bank $_FLASHNAME efm32 0 0 0 0 $_TARGETNAME
     It supports writing to the user data page, as well as the portion
     of the lockbits page past 512 bytes on chips with larger page
     sizes.  The latter is used by the SiLabs bootloader/AppLoader
     system for encryption keys.  Setting protection on these pages is
     currently not supported.
          flash bank userdata.flash efm32 0x0FE00000 0 0 0 $_TARGETNAME
          flash bank lockbits.flash efm32 0x0FE04000 0 0 0 $_TARGETNAME

     A special feature of efm32 controllers is that it is possible to
     completely disable the debug interface by writing the correct
     values to the 'Debug Lock Word'.  OpenOCD supports this via the
     following command:
          efm32 debuglock num
     The NUM parameter is a value shown by 'flash banks'.  Note that in
     order for this command to take effect, the target needs to be
     reset.  _The current implementation is incomplete.  Unprotecting
     flash pages is not supported._

 -- Flash Driver: esirisc
     Members of the eSi-RISC family may optionally include internal
     flash programmed via the eSi-TSMC Flash interface.  Additional
     parameters are required to configure the driver: 'cfg_address' is
     the base address of the configuration register interface,
     'clock_hz' is the expected clock frequency, and 'wait_states' is
     the number of configured read wait states.

          flash bank $_FLASHNAME esirisc base_address size_bytes 0 0 \
                     $_TARGETNAME cfg_address clock_hz wait_states

      -- Command: esirisc flash mass_erase bank_id
          Erase all pages in data memory for the bank identified by
          'bank_id'.

      -- Command: esirisc flash ref_erase bank_id
          Erase the reference cell for the bank identified by 'bank_id'.
          _This is an uncommon operation._

 -- Flash Driver: fm3
     All members of the FM3 microcontroller family from Fujitsu include
     internal flash and use ARM Cortex-M3 cores.  The FM3 driver uses
     the TARGET parameter to select the correct bank config, it can
     currently be one of the following: 'mb9bfxx1.cpu', 'mb9bfxx2.cpu',
     'mb9bfxx3.cpu', 'mb9bfxx4.cpu', 'mb9bfxx5.cpu' or 'mb9bfxx6.cpu'.

          flash bank $_FLASHNAME fm3 0 0 0 0 $_TARGETNAME

 -- Flash Driver: fm4
     All members of the FM4 microcontroller family from Spansion
     (formerly Fujitsu) include internal flash and use ARM Cortex-M4
     cores.  The FM4 driver uses a FAMILY parameter to select the
     correct bank config, it can currently be one of the following:
     'MB9BFx64', 'MB9BFx65', 'MB9BFx66', 'MB9BFx67', 'MB9BFx68',
     'S6E2Cx8', 'S6E2Cx9', 'S6E2CxA' or 'S6E2Dx', with 'x' treated as
     wildcard and otherwise case (and any trailing characters) ignored.

          flash bank ${_FLASHNAME}0 fm4 0x00000000 0 0 0 \
                     $_TARGETNAME S6E2CCAJ0A
          flash bank ${_FLASHNAME}1 fm4 0x00100000 0 0 0 \
                     $_TARGETNAME S6E2CCAJ0A
     _The current implementation is incomplete.  Protection is not
     supported, nor is Chip Erase (only Sector Erase is implemented)._

 -- Flash Driver: kinetis
     Kx, KLx, KVx and KE1x members of the Kinetis microcontroller family
     from NXP (former Freescale) include internal flash and use ARM
     Cortex-M0+ or M4 cores.  The driver automatically recognizes flash
     size and a number of flash banks (1-4) using the chip
     identification register, and autoconfigures itself.  Use kinetis_ke
     driver for KE0x and KEAx devices.

     The KINETIS driver defines option:
        * -sim-base ADDR ...  base of System Integration Module where
          chip identification resides.  Driver tries two known locations
          if option is omitted.

          flash bank $_FLASHNAME kinetis 0 0 0 0 $_TARGETNAME

      -- Config Command: kinetis create_banks
          Configuration command enables automatic creation of additional
          flash banks based on real flash layout of device.  Banks are
          created during device probe.  Use 'flash probe 0' to force
          probe.

      -- Command: kinetis fcf_source [protection|write]
          Select what source is used when writing to a Flash
          Configuration Field.  'protection' mode builds FCF content
          from protection bits previously set by 'flash protect'
          command.  This mode is default.  MCU is protected from
          unwanted locking by immediate writing FCF after erase of
          relevant sector.  'write' mode enables direct write to FCF.
          Protection cannot be set by 'flash protect' command.  FCF is
          written along with the rest of a flash image.  _BEWARE:
          Incorrect flash configuration may permanently lock the
          device!_

      -- Command: kinetis fopt [num]
          Set value to write to FOPT byte of Flash Configuration Field.
          Used in kinetis 'fcf_source protection' mode only.

      -- Command: kinetis mdm check_security
          Checks status of device security lock.  Used internally in
          examine-end and examine-fail event.

      -- Command: kinetis mdm halt
          Issues a halt via the MDM-AP. This command can be used to
          break a watchdog reset loop when connecting to an unsecured
          target.

      -- Command: kinetis mdm mass_erase
          Issues a complete flash erase via the MDM-AP. This can be used
          to erase a chip back to its factory state, removing security.
          It does not require the processor to be halted, however the
          target will remain in a halted state after this command
          completes.

      -- Command: kinetis nvm_partition
          For FlexNVM devices only (KxxDX and KxxFX). Command shows or
          sets data flash or EEPROM backup size in kilobytes, sets two
          EEPROM blocks sizes in bytes and enables/disables loading of
          EEPROM contents to FlexRAM during reset.

          For details see device reference manual, Flash Memory Module,
          Program Partition command.

          Setting is possible only once after mass_erase.  Reset the
          device after partition setting.

          Show partition size:
               kinetis nvm_partition info

          Set 32 KB data flash, rest of FlexNVM is EEPROM backup.
          EEPROM has two blocks of 512 and 1536 bytes and its contents
          is loaded to FlexRAM during reset:
               kinetis nvm_partition dataflash 32 512 1536 on

          Set 16 KB EEPROM backup, rest of FlexNVM is a data flash.
          EEPROM has two blocks of 1024 bytes and its contents is not
          loaded to FlexRAM during reset:
               kinetis nvm_partition eebkp 16 1024 1024 off

      -- Command: kinetis mdm reset
          Issues a reset via the MDM-AP. This causes the MCU to output a
          low pulse on the RESET pin, which can be used to reset other
          hardware on board.

      -- Command: kinetis disable_wdog
          For Kx devices only (KLx has different COP watchdog, it is not
          supported).  Command disables watchdog timer.

 -- Flash Driver: kinetis_ke
     KE0x and KEAx members of the Kinetis microcontroller family from
     NXP include internal flash and use ARM Cortex-M0+.  The driver
     automatically recognizes the KE0x sub-family using the chip
     identification register, and autoconfigures itself.  Use kinetis
     (not kinetis_ke) driver for KE1x devices.

          flash bank $_FLASHNAME kinetis_ke 0 0 0 0 $_TARGETNAME

      -- Command: kinetis_ke mdm check_security
          Checks status of device security lock.  Used internally in
          examine-end event.

      -- Command: kinetis_ke mdm mass_erase
          Issues a complete Flash erase via the MDM-AP. This can be used
          to erase a chip back to its factory state.  Command removes
          security lock from a device (use of SRST highly recommended).
          It does not require the processor to be halted.

      -- Command: kinetis_ke disable_wdog
          Command disables watchdog timer.

 -- Flash Driver: lpc2000
     This is the driver to support internal flash of all members of the
     LPC11(x)00 and LPC1300 microcontroller families and most members of
     the LPC800, LPC1500, LPC1700, LPC1800, LPC2000, LPC4000, LPC54100,
     LPC8Nxx and NHS31xx microcontroller families from NXP.

          Note: There are LPC2000 devices which are not supported by the
          LPC2000 driver: The LPC2888 is supported by the LPC288X
          driver.  The LPC29xx family is supported by the LPC2900
          driver.

     The LPC2000 driver defines two mandatory and two optional
     parameters, which must appear in the following order:

        * VARIANT ...  required, may be 'lpc2000_v1' (older LPC21xx and
          LPC22xx) 'lpc2000_v2' (LPC213x, LPC214x, LPC210[123], LPC23xx
          and LPC24xx) 'lpc1700' (LPC175x and LPC176x and LPC177x/8x)
          'lpc4300' - available also as 'lpc1800' alias (LPC18x[2357]
          and LPC43x[2357]) 'lpc800' (LPC8xx) 'lpc1100' (LPC11(x)xx and
          LPC13xx) 'lpc1500' (LPC15xx) 'lpc54100' (LPC541xx) 'lpc4000'
          (LPC40xx) or 'auto' - automatically detects flash variant and
          size for LPC11(x)00, LPC8xx, LPC13xx, LPC17xx, LPC40xx,
          LPC8Nxx and NHS31xx
        * CLOCK_KHZ ...  the frequency, in kiloHertz, at which the core
          is running
        * 'calc_checksum' ...  optional (but you probably want to
          provide this!), telling the driver to calculate a valid
          checksum for the exception vector table.
               Note: If you don't provide 'calc_checksum' when you're
               writing the vector table, the boot ROM will almost
               certainly ignore your flash image.  However, if you do
               provide it, with most tool chains 'verify_image' will
               fail.
        * 'iap_entry' ...  optional telling the driver to use a
          different ROM IAP entry point.

     LPC flashes don't require the chip and bus width to be specified.

          flash bank $_FLASHNAME lpc2000 0x0 0x7d000 0 0 $_TARGETNAME \
                lpc2000_v2 14765 calc_checksum

      -- Command: lpc2000 part_id bank
          Displays the four byte part identifier associated with the
          specified flash BANK.

 -- Flash Driver: lpc288x
     The LPC2888 microcontroller from NXP needs slightly different flash
     support from its lpc2000 siblings.  The LPC288X driver defines one
     mandatory parameter, the programming clock rate in Hz.  LPC flashes
     don't require the chip and bus width to be specified.

          flash bank $_FLASHNAME lpc288x 0 0 0 0 $_TARGETNAME 12000000

 -- Flash Driver: lpc2900
     This driver supports the LPC29xx ARM968E based microcontroller
     family from NXP.

     The predefined parameters BASE, SIZE, CHIP_WIDTH and BUS_WIDTH of
     the 'flash bank' command are ignored.  Flash size and sector layout
     are auto-configured by the driver.  The driver has one additional
     mandatory parameter: The CPU clock rate (in kHz) at the time the
     flash operations will take place.  Most of the time this will not
     be the crystal frequency, but a higher PLL frequency.  The
     'reset-init' event handler in the board script is usually the place
     where you start the PLL.

     The driver rejects flashless devices (currently the LPC2930).

     The EEPROM in LPC2900 devices is not mapped directly into the
     address space.  It must be handled much more like NAND flash
     memory, and will therefore be handled by a separate
     'lpc2900_eeprom' driver (not yet available).

     Sector protection in terms of the LPC2900 is handled transparently.
     Every time a sector needs to be erased or programmed, it is
     automatically unprotected.  What is shown as protection status in
     the 'flash info' command, is actually the LPC2900 _sector
     security_.  This is a mechanism to prevent a sector from ever being
     erased or programmed again.  As this is an irreversible mechanism,
     it is handled by a special command ('lpc2900 secure_sector'), and
     not by the standard 'flash protect' command.

     Example for a 125 MHz clock frequency:
          flash bank $_FLASHNAME lpc2900 0 0 0 0 $_TARGETNAME 125000

     Some 'lpc2900'-specific commands are defined.  In the following
     command list, the BANK parameter is the bank number as obtained by
     the 'flash banks' command.

      -- Command: lpc2900 signature bank
          Calculates a 128-bit hash value, the _signature_, from the
          whole flash content.  This is a hardware feature of the flash
          block, hence the calculation is very fast.  You may use this
          to verify the content of a programmed device against a known
          signature.  Example:
               lpc2900 signature 0
                 signature: 0x5f40cdc8:0xc64e592e:0x10490f89:0x32a0f317

      -- Command: lpc2900 read_custom bank filename
          Reads the 912 bytes of customer information from the flash
          index sector, and saves it to a file in binary format.
          Example:
               lpc2900 read_custom 0 /path_to/customer_info.bin

     The index sector of the flash is a _write-only_ sector.  It cannot
     be erased!  In order to guard against unintentional write access,
     all following commands need to be preceded by a successful call to
     the 'password' command:

      -- Command: lpc2900 password bank password
          You need to use this command right before each of the
          following commands: 'lpc2900 write_custom', 'lpc2900
          secure_sector', 'lpc2900 secure_jtag'.

          The password string is fixed to "I_know_what_I_am_doing".
          Example:
               lpc2900 password 0 I_know_what_I_am_doing
                 Potentially dangerous operation allowed in next command!

      -- Command: lpc2900 write_custom bank filename type
          Writes the content of the file into the customer info space of
          the flash index sector.  The filetype can be specified with
          the TYPE field.  Possible values for TYPE are: BIN (binary),
          IHEX (Intel hex format), ELF (ELF binary) or S19 (Motorola
          S-records).  The file must contain a single section, and the
          contained data length must be exactly 912 bytes.
               Attention: This cannot be reverted!  Be careful!
          Example:
               lpc2900 write_custom 0 /path_to/customer_info.bin bin

      -- Command: lpc2900 secure_sector bank first last
          Secures the sector range from FIRST to LAST (including)
          against further program and erase operations.  The sector
          security will be effective after the next power cycle.
               Attention: This cannot be reverted!  Be careful!
          Secured sectors appear as _protected_ in the 'flash info'
          command.  Example:
               lpc2900 secure_sector 0 1 1
               flash info 0
                 #0 : lpc2900 at 0x20000000, size 0x000c0000, (...)
                         #  0: 0x00000000 (0x2000 8kB) not protected
                         #  1: 0x00002000 (0x2000 8kB) protected
                         #  2: 0x00004000 (0x2000 8kB) not protected

      -- Command: lpc2900 secure_jtag bank
          Irreversibly disable the JTAG port.  The new JTAG security
          setting will be effective after the next power cycle.
               Attention: This cannot be reverted!  Be careful!
          Examples:
               lpc2900 secure_jtag 0

 -- Flash Driver: mdr
     This drivers handles the integrated NOR flash on Milandr Cortex-M
     based controllers.  A known limitation is that the Info memory
     can't be read or verified as it's not memory mapped.

          flash bank <name> mdr <base> <size> \
                0 0 <target#> TYPE PAGE_COUNT SEC_COUNT

        * TYPE - 0 for main memory, 1 for info memory
        * PAGE_COUNT - total number of pages
        * SEC_COUNT - number of sector per page count

     Example usage:
          if { [info exists IMEMORY] && [string equal $IMEMORY true] } {
             flash bank ${_CHIPNAME}_info.flash mdr 0x00000000 0x01000 \
                   0 0 $_TARGETNAME 1 1 4
          } else {
             flash bank $_CHIPNAME.flash mdr 0x00000000 0x20000 \
                   0 0 $_TARGETNAME 0 32 4
          }

 -- Flash Driver: msp432
     All versions of the SimpleLink MSP432 microcontrollers from Texas
     Instruments include internal flash.  The msp432 flash driver
     automatically recognizes the specific version's flash parameters
     and autoconfigures itself.  Main program flash starts at address 0.
     The information flash region on MSP432P4 versions starts at address
     0x200000.

          flash bank $_FLASHNAME msp432 0 0 0 0 $_TARGETNAME

      -- Command: msp432 mass_erase bank_id [main|all]
          Performs a complete erase of flash.  By default, 'mass_erase'
          will erase only the main program flash.

          On MSP432P4 versions, using 'mass_erase all' will erase both
          the main program and information flash regions.  To also erase
          the BSL in information flash, the user must first use the
          'bsl' command.

      -- Command: msp432 bsl bank_id [unlock|lock]
          On MSP432P4 versions, 'bsl' unlocks and locks the bootstrap
          loader (BSL) region in information flash so that flash
          commands can erase or write the BSL. Leave the BSL locked to
          prevent accidentally corrupting the bootstrap loader.

          To erase and program the BSL:
               msp432 bsl unlock
               flash erase_address 0x202000 0x2000
               flash write_image bsl.bin 0x202000
               msp432 bsl lock

 -- Flash Driver: niietcm4
     This drivers handles the integrated NOR flash on NIIET Cortex-M4
     based controllers.  Flash size and sector layout are
     auto-configured by the driver.  Main flash memory is called
     "Bootflash" and has main region and info region.  Info region is
     NOT memory mapped by default, but it can replace first part of main
     region if needed.  Full erase, single and block writes are
     supported for both main and info regions.  There is additional not
     memory mapped flash called "Userflash", which also have division
     into regions: main and info.  Purpose of userflash - to store
     system and user settings.  Driver has special commands to perform
     operations with this memory.

          flash bank $_FLASHNAME niietcm4 0 0 0 0 $_TARGETNAME

     Some niietcm4-specific commands are defined:

      -- Command: niietcm4 uflash_read_byte bank ('main'|'info') address
          Read byte from main or info userflash region.

      -- Command: niietcm4 uflash_write_byte bank ('main'|'info')
               address value
          Write byte to main or info userflash region.

      -- Command: niietcm4 uflash_full_erase bank
          Erase all userflash including info region.

      -- Command: niietcm4 uflash_erase bank ('main'|'info')
               first_sector last_sector
          Erase sectors of main or info userflash region, starting at
          sector first up to and including last.

      -- Command: niietcm4 uflash_protect_check bank ('main'|'info')
          Check sectors protect.

      -- Command: niietcm4 uflash_protect bank ('main'|'info')
               first_sector last_sector ('on'|'off')
          Protect sectors of main or info userflash region, starting at
          sector first up to and including last.

      -- Command: niietcm4 bflash_info_remap bank ('on'|'off')
          Enable remapping bootflash info region to 0x00000000 (or
          0x40000000 if external memory boot used).

      -- Command: niietcm4 extmem_cfg bank
               ('gpioa'|'gpiob'|'gpioc'|'gpiod'|'gpioe'|'gpiof'|'gpiog'|'gpioh')
               pin_num ('func1'|'func3')
          Configure external memory interface for boot.

      -- Command: niietcm4 service_mode_erase bank
          Perform emergency erase of all flash (bootflash and
          userflash).

      -- Command: niietcm4 driver_info bank
          Show information about flash driver.

 -- Flash Driver: npcx
     All versions of the NPCX microcontroller families from Nuvoton
     include internal flash.  The NPCX flash driver supports the NPCX
     family of devices.  The driver automatically recognizes the
     specific version's flash parameters and autoconfigures itself.  The
     flash bank starts at address 0x64000000.

          flash bank $_FLASHNAME npcx 0x64000000 0 0 0 $_TARGETNAME

 -- Flash Driver: nrf5
     All members of the nRF51 microcontroller families from Nordic
     Semiconductor include internal flash and use ARM Cortex-M0 core.
     nRF52 family powered by ARM Cortex-M4 or M4F core is supported too.
     nRF52832 is fully supported including BPROT flash protection
     scheme.  nRF52833 and nRF52840 devices are supported with the
     exception of security extensions (flash access control list - ACL).

          flash bank $_FLASHNAME nrf5 0 0x00000000 0 0 $_TARGETNAME

     Some nrf5-specific commands are defined:

      -- Command: nrf5 mass_erase
          Erases the contents of the code memory and user information
          configuration registers as well.  It must be noted that this
          command works only for chips that do not have factory
          pre-programmed region 0 code.

      -- Command: nrf5 info
          Decodes and shows information from FICR and UICR registers.

 -- Flash Driver: ocl
     This driver is an implementation of the "on chip flash loader"
     protocol proposed by Pavel Chromy.

     It is a minimalistic command-response protocol intended to be used
     over a DCC when communicating with an internal or external flash
     loader running from RAM. An example implementation for AT91SAM7x is
     available in 'contrib/loaders/flash/at91sam7x/'.

          flash bank $_FLASHNAME ocl 0 0 0 0 $_TARGETNAME

 -- Flash Driver: pic32mx
     The PIC32MX microcontrollers are based on the MIPS 4K cores, and
     integrate flash memory.

          flash bank $_FLASHNAME pix32mx 0x1fc00000 0 0 0 $_TARGETNAME
          flash bank $_FLASHNAME pix32mx 0x1d000000 0 0 0 $_TARGETNAME

     Some pic32mx-specific commands are defined:
      -- Command: pic32mx pgm_word address value bank
          Programs the specified 32-bit VALUE at the given ADDRESS in
          the specified chip BANK.
      -- Command: pic32mx unlock bank
          Unlock and erase specified chip BANK.  This will remove any
          Code Protection.

 -- Flash Driver: psoc4
     All members of the PSoC 41xx/42xx microcontroller family from
     Cypress include internal flash and use ARM Cortex-M0 cores.  The
     driver automatically recognizes a number of these chips using the
     chip identification register, and autoconfigures itself.

     Note: Erased internal flash reads as 00.  System ROM of PSoC 4 does
     not implement erase of a flash sector.

          flash bank $_FLASHNAME psoc4 0 0 0 0 $_TARGETNAME

     psoc4-specific commands
      -- Command: psoc4 flash_autoerase num (on|off)
          Enables or disables autoerase mode for a flash bank.

          If flash_autoerase is off, use mass_erase before flash
          programming.  Flash erase command fails if region to erase is
          not whole flash memory.

          If flash_autoerase is on, a sector is both erased and
          programmed in one system ROM call.  Flash erase command is
          ignored.  This mode is suitable for gdb load.

          The NUM parameter is a value shown by 'flash banks'.

      -- Command: psoc4 mass_erase num
          Erases the contents of the flash memory, protection and
          security lock.

          The NUM parameter is a value shown by 'flash banks'.

 -- Flash Driver: psoc5lp
     All members of the PSoC 5LP microcontroller family from Cypress
     include internal program flash and use ARM Cortex-M3 cores.  The
     driver probes for a number of these chips and autoconfigures
     itself, apart from the base address.

          flash bank $_FLASHNAME psoc5lp 0x00000000 0 0 0 $_TARGETNAME

     Note: PSoC 5LP chips can be configured to have ECC enabled or
     disabled.
          Attention: If flash operations are performed in ECC-disabled
          mode, they will also affect the ECC flash region.  Erasing a
          16k flash sector in the 0x00000000 area will then also erase
          the corresponding 2k data bytes in the 0x48000000 area.
          Writing to the ECC data bytes in ECC-disabled mode is not
          implemented.

     Commands defined in the PSOC5LP driver:

      -- Command: psoc5lp mass_erase
          Erases all flash data and ECC/configuration bytes, all flash
          protection rows, and all row latches in all flash arrays on
          the device.

 -- Flash Driver: psoc5lp_eeprom
     All members of the PSoC 5LP microcontroller family from Cypress
     include internal EEPROM and use ARM Cortex-M3 cores.  The driver
     probes for a number of these chips and autoconfigures itself, apart
     from the base address.

          flash bank $_CHIPNAME.eeprom psoc5lp_eeprom 0x40008000 0 0 0 \
                     $_TARGETNAME

 -- Flash Driver: psoc5lp_nvl
     All members of the PSoC 5LP microcontroller family from Cypress
     include internal Nonvolatile Latches and use ARM Cortex-M3 cores.
     The driver probes for a number of these chips and autoconfigures
     itself.

          flash bank $_CHIPNAME.nvl psoc5lp_nvl 0 0 0 0 $_TARGETNAME

     PSoC 5LP chips have multiple NV Latches:

        * Device Configuration NV Latch - 4 bytes
        * Write Once (WO) NV Latch - 4 bytes

     Note: This driver only implements the Device Configuration NVL.

     The PSOC5LP driver reads the ECC mode from Device Configuration
     NVL.
          Attention: Switching ECC mode via write to Device
          Configuration NVL will require a reset after successful write.

 -- Flash Driver: psoc6
     Supports PSoC6 (CY8C6xxx) family of Cypress microcontrollers.
     PSoC6 is a dual-core device with CM0+ and CM4 cores.  Both cores
     share the same Flash/RAM/MMIO address space.

     Flash in PSoC6 is split into three regions:
        * Main Flash - this is the main storage for user application.
          Total size varies among devices, sector size: 256 kBytes, row
          size: 512 bytes.  Supports erase operation on individual rows.
        * Work Flash - intended to be used as storage for user data
          (e.g.  EEPROM emulation).  Total size: 32 KBytes, sector size:
          32 KBytes, row size: 512 bytes.
        * Supervisory Flash - special region which contains
          device-specific service data.  This region does not support
          erase operation.  Only few rows can be programmed by the user,
          most of the rows are read only.  Programming operation will
          erase row automatically.

     All three flash regions are supported by the driver.  Flash
     geometry is detected automatically by parsing data in
     SPCIF_GEOMETRY register.

     PSoC6 is equipped with NOR Flash so erased Flash reads as 0x00.

          flash bank main_flash_cm0 psoc6 0x10000000 0 0 0 \
                     ${TARGET}.cm0
          flash bank work_flash_cm0 psoc6 0x14000000 0 0 0 \
                     ${TARGET}.cm0
          flash bank super_flash_user_cm0 psoc6 0x16000800 0 0 0 \
                     ${TARGET}.cm0
          flash bank super_flash_nar_cm0 psoc6 0x16001A00 0 0 0 \
                     ${TARGET}.cm0
          flash bank super_flash_key_cm0 psoc6 0x16005A00 0 0 0 \
                     ${TARGET}.cm0
          flash bank super_flash_toc2_cm0 psoc6 0x16007C00 0 0 0 \
                     ${TARGET}.cm0

          flash bank main_flash_cm4 psoc6 0x10000000 0 0 0 \
                     ${TARGET}.cm4
          flash bank work_flash_cm4 psoc6 0x14000000 0 0 0 \
                     ${TARGET}.cm4
          flash bank super_flash_user_cm4 psoc6 0x16000800 0 0 0 \
                     ${TARGET}.cm4
          flash bank super_flash_nar_cm4 psoc6 0x16001A00 0 0 0 \
                     ${TARGET}.cm4
          flash bank super_flash_key_cm4 psoc6 0x16005A00 0 0 0 \
                     ${TARGET}.cm4
          flash bank super_flash_toc2_cm4 psoc6 0x16007C00 0 0 0 \
                     ${TARGET}.cm4

     psoc6-specific commands
      -- Command: psoc6 reset_halt
          Command can be used to simulate broken Vector Catch from
          gdbinit or tcl scripts.  When invoked for CM0+ target, it will
          set break point at application entry point and issue
          SYSRESETREQ. This will reset both cores and all peripherals.
          CM0+ will reset CM4 during boot anyway so this is safe.  On
          CM4 target, VECTRESET is used instead of SYSRESETREQ to avoid
          unwanted reset of CM0+;

      -- Command: psoc6 mass_erase num
          Erases the contents given flash bank.  The NUM parameter is a
          value shown by 'flash banks'.  Note: only Main and Work flash
          regions support Erase operation.

 -- Flash Driver: rp2040
     Supports RP2040 "Raspberry Pi Pico" microcontroller.  RP2040 is a
     dual-core device with two CM0+ cores.  Both cores share the same
     Flash/RAM/MMIO address space.  Non-volatile storage is achieved
     with an external QSPI flash; a Boot ROM provides helper functions.

          flash bank $_FLASHNAME rp2040_flash $_FLASHBASE $_FLASHSIZE 1 32 $_TARGETNAME

 -- Flash Driver: sim3x
     All members of the SiM3 microcontroller family from Silicon
     Laboratories include internal flash and use ARM Cortex-M3 cores.
     It supports both JTAG and SWD interface.  The SIM3X driver tries to
     probe the device to auto detect the MCU. If this fails, it will use
     the SIZE parameter as the size of flash bank.

          flash bank $_FLASHNAME sim3x 0 $_CPUROMSIZE 0 0 $_TARGETNAME

     There are 2 commands defined in the SIM3X driver:

      -- Command: sim3x mass_erase
          Erases the complete flash.  This is used to unlock the flash.
          And this command is only possible when using the SWD
          interface.

      -- Command: sim3x lock
          Lock the flash.  To unlock use the 'sim3x mass_erase' command.

 -- Flash Driver: stellaris
     All members of the Stellaris LM3Sxxx, LM4x and Tiva C
     microcontroller families from Texas Instruments include internal
     flash.  The driver automatically recognizes a number of these chips
     using the chip identification register, and autoconfigures itself.

          flash bank $_FLASHNAME stellaris 0 0 0 0 $_TARGETNAME

      -- Command: stellaris recover
          Performs the _Recovering a "Locked" Device_ procedure to
          restore the flash and its associated nonvolatile registers to
          their factory default values (erased).  This is the only way
          to remove flash protection or re-enable debugging if that
          capability has been disabled.

          Note that the final "power cycle the chip" step in this
          procedure must be performed by hand, since OpenOCD can't do
          it.
               Warning: if more than one Stellaris chip is connected,
               the procedure is applied to all of them.

 -- Flash Driver: stm32f1x
     All members of the STM32F0, STM32F1 and STM32F3 microcontroller
     families from STMicroelectronics and all members of the GD32F1x0,
     GD32F3x0 and GD32E23x microcontroller families from GigaDevice
     include internal flash and use ARM Cortex-M0/M3/M4/M23 cores.  The
     driver automatically recognizes a number of these chips using the
     chip identification register, and autoconfigures itself.

          flash bank $_FLASHNAME stm32f1x 0 0 0 0 $_TARGETNAME

     Note that some devices have been found that have a flash size
     register that contains an invalid value, to workaround this issue
     you can override the probed value used by the flash driver.

          flash bank $_FLASHNAME stm32f1x 0 0x20000 0 0 $_TARGETNAME

     If you have a target with dual flash banks then define the second
     bank as per the following example.
          flash bank $_FLASHNAME stm32f1x 0x08080000 0 0 0 $_TARGETNAME

     Some stm32f1x-specific commands are defined:

      -- Command: stm32f1x lock num
          Locks the entire stm32 device against reading.  The NUM
          parameter is a value shown by 'flash banks'.

      -- Command: stm32f1x unlock num
          Unlocks the entire stm32 device for reading.  This command
          will cause a mass erase of the entire stm32 device if
          previously locked.  The NUM parameter is a value shown by
          'flash banks'.

      -- Command: stm32f1x mass_erase num
          Mass erases the entire stm32 device.  The NUM parameter is a
          value shown by 'flash banks'.

      -- Command: stm32f1x options_read num
          Reads and displays active stm32 option bytes loaded during POR
          or upon executing the 'stm32f1x options_load' command.  The
          NUM parameter is a value shown by 'flash banks'.

      -- Command: stm32f1x options_write num (SWWDG|HWWDG)
               (RSTSTNDBY|NORSTSTNDBY) (RSTSTOP|NORSTSTOP) (USEROPT
               user_data)
          Writes the stm32 option byte with the specified values.  The
          NUM parameter is a value shown by 'flash banks'.  The
          USER_DATA parameter is content of higher 16 bits of the option
          byte register (Data0 and Data1 as one 16bit number).

      -- Command: stm32f1x options_load num
          Generates a special kind of reset to re-load the stm32 option
          bytes written by the 'stm32f1x options_write' or 'flash
          protect' commands without having to power cycle the target.
          Not applicable to stm32f1x devices.  The NUM parameter is a
          value shown by 'flash banks'.

 -- Flash Driver: stm32f2x
     All members of the STM32F2, STM32F4 and STM32F7 microcontroller
     families from STMicroelectronics include internal flash and use ARM
     Cortex-M3/M4/M7 cores.  The driver automatically recognizes a
     number of these chips using the chip identification register, and
     autoconfigures itself.

          flash bank $_FLASHNAME stm32f2x 0 0 0 0 $_TARGETNAME

     If you use OTP (One-Time Programmable) memory define it as a second
     bank as per the following example.
          flash bank $_FLASHNAME stm32f2x 0x1FFF7800 0 0 0 $_TARGETNAME

      -- Command: stm32f2x otp num (enable|disable|show)
          Enables or disables OTP write commands for bank NUM.  The NUM
          parameter is a value shown by 'flash banks'.

     Note that some devices have been found that have a flash size
     register that contains an invalid value, to workaround this issue
     you can override the probed value used by the flash driver.

          flash bank $_FLASHNAME stm32f2x 0 0x20000 0 0 $_TARGETNAME

     Some stm32f2x-specific commands are defined:

      -- Command: stm32f2x lock num
          Locks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32f2x unlock num
          Unlocks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32f2x mass_erase num
          Mass erases the entire stm32f2x device.  The NUM parameter is
          a value shown by 'flash banks'.

      -- Command: stm32f2x options_read num
          Reads and displays user options and (where implemented)
          boot_addr0, boot_addr1, optcr2.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32f2x options_write num user_options boot_addr0
               boot_addr1
          Writes user options and (where implemented) boot_addr0 and
          boot_addr1 in raw format.  Warning: The meaning of the various
          bits depends on the device, always check datasheet!  The NUM
          parameter is a value shown by 'flash banks', USER_OPTIONS a 12
          bit value, consisting of bits 31-28 and 7-0 of FLASH_OPTCR,
          BOOT_ADDR0 and BOOT_ADDR1 two halfwords (of FLASH_OPTCR1).

      -- Command: stm32f2x optcr2_write num optcr2
          Writes FLASH_OPTCR2 options.  Warning: Clearing PCROPi bits
          requires a full mass erase!  The NUM parameter is a value
          shown by 'flash banks', OPTCR2 a 32-bit word.

 -- Flash Driver: stm32h7x
     All members of the STM32H7 microcontroller families from
     STMicroelectronics include internal flash and use ARM Cortex-M7
     core.  The driver automatically recognizes a number of these chips
     using the chip identification register, and autoconfigures itself.

          flash bank $_FLASHNAME stm32h7x 0 0 0 0 $_TARGETNAME

     Note that some devices have been found that have a flash size
     register that contains an invalid value, to workaround this issue
     you can override the probed value used by the flash driver.

          flash bank $_FLASHNAME stm32h7x 0 0x20000 0 0 $_TARGETNAME

     Some stm32h7x-specific commands are defined:

      -- Command: stm32h7x lock num
          Locks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32h7x unlock num
          Unlocks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32h7x mass_erase num
          Mass erases the entire stm32h7x device.  The NUM parameter is
          a value shown by 'flash banks'.

      -- Command: stm32h7x option_read num reg_offset
          Reads an option byte register from the stm32h7x device.  The
          NUM parameter is a value shown by 'flash banks', REG_OFFSET is
          the register offset of the option byte to read from the used
          bank registers' base.  For example: in STM32H74x/H75x the bank
          1 registers' base is 0x52002000 and 0x52002100 for bank 2.

          Example usage:
               # read OPTSR_CUR
               stm32h7x option_read 0 0x1c
               # read WPSN_CUR1R
               stm32h7x option_read 0 0x38
               # read WPSN_CUR2R
               stm32h7x option_read 1 0x38

      -- Command: stm32h7x option_write num reg_offset value [reg_mask]
          Writes an option byte register of the stm32h7x device.  The
          NUM parameter is a value shown by 'flash banks', REG_OFFSET is
          the register offset of the option byte to write from the used
          bank register base, and REG_MASK is the mask to apply when
          writing the register (only bits with a '1' will be touched).

          Example usage:
               # swap bank 1 and bank 2 in dual bank devices
               # by setting SWAP_BANK_OPT bit in OPTSR_PRG
               stm32h7x option_write 0 0x20 0x8000000 0x8000000

 -- Flash Driver: stm32lx
     All members of the STM32L0 and STM32L1 microcontroller families
     from STMicroelectronics include internal flash and use ARM
     Cortex-M3 and Cortex-M0+ cores.  The driver automatically
     recognizes a number of these chips using the chip identification
     register, and autoconfigures itself.

          flash bank $_FLASHNAME stm32lx 0 0 0 0 $_TARGETNAME

     Note that some devices have been found that have a flash size
     register that contains an invalid value, to workaround this issue
     you can override the probed value used by the flash driver.  If you
     use 0 as the bank base address, it tells the driver to autodetect
     the bank location assuming you're configuring the second bank.

          flash bank $_FLASHNAME stm32lx 0x08000000 0x20000 0 0 $_TARGETNAME

     Some stm32lx-specific commands are defined:

      -- Command: stm32lx lock num
          Locks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32lx unlock num
          Unlocks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32lx mass_erase num
          Mass erases the entire stm32lx device (all flash banks and
          EEPROM data).  This is the only way to unlock a protected
          flash (unless RDP Level is 2 which can't be unlocked at all).
          The NUM parameter is a value shown by 'flash banks'.

 -- Flash Driver: stm32l4x
     All members of the STM32 G0, G4, L4, L4+, L5, U5, WB and WL
     microcontroller families from STMicroelectronics include internal
     flash and use ARM Cortex-M0+, M4 and M33 cores.  The driver
     automatically recognizes a number of these chips using the chip
     identification register, and autoconfigures itself.

          flash bank $_FLASHNAME stm32l4x 0 0 0 0 $_TARGETNAME

     If you use OTP (One-Time Programmable) memory define it as a second
     bank as per the following example.
          flash bank $_FLASHNAME stm32l4x 0x1FFF7000 0 0 0 $_TARGETNAME

      -- Command: stm32l4x otp num (enable|disable|show)
          Enables or disables OTP write commands for bank NUM.  The NUM
          parameter is a value shown by 'flash banks'.

     Note that some devices have been found that have a flash size
     register that contains an invalid value, to workaround this issue
     you can override the probed value used by the flash driver.
     However, specifying a wrong value might lead to a completely wrong
     flash layout, so this feature must be used carefully.

          flash bank $_FLASHNAME stm32l4x 0x08000000 0x40000 0 0 $_TARGETNAME

     Some stm32l4x-specific commands are defined:

      -- Command: stm32l4x lock num
          Locks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

          _Note:_ To apply the protection change immediately, use
          'stm32l4x option_load'.

      -- Command: stm32l4x unlock num
          Unlocks the entire stm32 device.  The NUM parameter is a value
          shown by 'flash banks'.

          _Note:_ To apply the protection change immediately, use
          'stm32l4x option_load'.

      -- Command: stm32l4x mass_erase num
          Mass erases the entire stm32l4x device.  The NUM parameter is
          a value shown by 'flash banks'.

      -- Command: stm32l4x option_read num reg_offset
          Reads an option byte register from the stm32l4x device.  The
          NUM parameter is a value shown by 'flash banks', REG_OFFSET is
          the register offset of the Option byte to read.

          For example to read the FLASH_OPTR register:
               stm32l4x option_read 0 0x20
               # Option Register (for STM32L4x): <0x40022020> = 0xffeff8aa
               # Option Register (for STM32WBx): <0x58004020> = ...
               # The correct flash base address will be used automatically

          The above example will read out the FLASH_OPTR register which
          contains the RDP option byte, Watchdog configuration, BOR
          level etc.

      -- Command: stm32l4x option_write num reg_offset reg_mask
          Write an option byte register of the stm32l4x device.  The NUM
          parameter is a value shown by 'flash banks', REG_OFFSET is the
          register offset of the Option byte to write, and REG_MASK is
          the mask to apply when writing the register (only bits with a
          '1' will be touched).

          _Note:_ To apply the option bytes change immediately, use
          'stm32l4x option_load'.

          For example to write the WRP1AR option bytes:
               stm32l4x option_write 0 0x28 0x00FF0000 0x00FF00FF

          The above example will write the WRP1AR option register
          configuring the Write protection Area A for bank 1.  The above
          example set WRP1AR_END=255, WRP1AR_START=0.  This will
          effectively write protect all sectors in flash bank 1.

      -- Command: stm32l4x wrp_info num [device_bank]
          List the protected areas using WRP. The NUM parameter is a
          value shown by 'flash banks'.  DEVICE_BANK parameter is
          optional, possible values 'bank1' or 'bank2', if not
          specified, the command will display the whole flash protected
          areas.

          Note: DEVICE_BANK is different from banks created using 'flash
          bank'.  Devices supported in this flash driver, can have main
          flash memory organized in single or dual-banks mode.  Thus the
          usage of DEVICE_BANK is meaningful only in dual-bank mode, to
          get write protected areas in a specific DEVICE_BANK

      -- Command: stm32l4x option_load num
          Forces a re-load of the option byte registers.  Will cause a
          system reset of the device.  The NUM parameter is a value
          shown by 'flash banks'.

      -- Command: stm32l4x trustzone num [enable | disable]
          Enables or disables Global TrustZone Security, using the TZEN
          option bit.  If neither 'enabled' nor 'disable' are specified,
          the command will display the TrustZone status.  _Note:_ This
          command works only with devices with TrustZone, eg.  STM32L5.
          _Note:_ This command will perform an OBL_Launch after
          modifying the TZEN.

 -- Flash Driver: str7x
     All members of the STR7 microcontroller family from
     STMicroelectronics include internal flash and use ARM7TDMI cores.
     The STR7X driver defines one mandatory parameter, VARIANT, which is
     either 'STR71x', 'STR73x' or 'STR75x'.

          flash bank $_FLASHNAME str7x \
                0x40000000 0x00040000 0 0 $_TARGETNAME STR71x

      -- Command: str7x disable_jtag bank
          Activate the Debug/Readout protection mechanism for the
          specified flash bank.

 -- Flash Driver: str9x
     Most members of the STR9 microcontroller family from
     STMicroelectronics include internal flash and use ARM966E cores.
     The str9 needs the flash controller to be configured using the
     'str9x flash_config' command prior to Flash programming.

          flash bank $_FLASHNAME str9x 0x40000000 0x00040000 0 0 $_TARGETNAME
          str9x flash_config 0 4 2 0 0x80000

      -- Command: str9x flash_config num bbsr nbbsr bbadr nbbadr
          Configures the str9 flash controller.  The NUM parameter is a
          value shown by 'flash banks'.

             * BBSR - Boot Bank Size register
             * NBBSR - Non Boot Bank Size register
             * BBADR - Boot Bank Start Address register
             * NBBADR - Boot Bank Start Address register

 -- Flash Driver: str9xpec

     Only use this driver for locking/unlocking the device or
     configuring the option bytes.  Use the standard str9 driver for
     programming.  Before using the flash commands the turbo mode must
     be enabled using the 'str9xpec enable_turbo' command.

     Here is some background info to help you better understand how this
     driver works.  OpenOCD has two flash drivers for the str9:
       1. Standard driver 'str9x' programmed via the str9 core.
          Normally used for flash programming as it is faster than the
          'str9xpec' driver.
       2. Direct programming 'str9xpec' using the flash controller.
          This is an ISC compliant (IEEE 1532) tap connected in series
          with the str9 core.  The str9 core does not need to be running
          to program using this flash driver.  Typical use for this
          driver is locking/unlocking the target and programming the
          option bytes.

     Before we run any commands using the 'str9xpec' driver we must
     first disable the str9 core.  This example assumes the 'str9xpec'
     driver has been configured for flash bank 0.
          # assert srst, we do not want core running
          # while accessing str9xpec flash driver
          adapter assert srst
          # turn off target polling
          poll off
          # disable str9 core
          str9xpec enable_turbo 0
          # read option bytes
          str9xpec options_read 0
          # re-enable str9 core
          str9xpec disable_turbo 0
          poll on
          reset halt
     The above example will read the str9 option bytes.  When performing
     a unlock remember that you will not be able to halt the str9 - it
     has been locked.  Halting the core is not required for the
     'str9xpec' driver as mentioned above, just issue the commands above
     manually or from a telnet prompt.

     Several str9xpec-specific commands are defined:

      -- Command: str9xpec disable_turbo num
          Restore the str9 into JTAG chain.

      -- Command: str9xpec enable_turbo num
          Enable turbo mode, will simply remove the str9 from the chain
          and talk directly to the embedded flash controller.

      -- Command: str9xpec lock num
          Lock str9 device.  The str9 will only respond to an unlock
          command that will erase the device.

      -- Command: str9xpec part_id num
          Prints the part identifier for bank NUM.

      -- Command: str9xpec options_cmap num (bank0|bank1)
          Configure str9 boot bank.

      -- Command: str9xpec options_lvdsel num (vdd|vdd_vddq)
          Configure str9 lvd source.

      -- Command: str9xpec options_lvdthd num (2.4v|2.7v)
          Configure str9 lvd threshold.

      -- Command: str9xpec options_lvdwarn bank (vdd|vdd_vddq)
          Configure str9 lvd reset warning source.

      -- Command: str9xpec options_read num
          Read str9 option bytes.

      -- Command: str9xpec options_write num
          Write str9 option bytes.

      -- Command: str9xpec unlock num
          unlock str9 device.

 -- Flash Driver: swm050
     All members of the swm050 microcontroller family from Foshan Synwit
     Tech.

          flash bank $_FLASHNAME swm050 0x0 0x2000 0 0 $_TARGETNAME

     One swm050-specific command is defined:

      -- Command: swm050 mass_erase bank_id
          Erases the entire flash bank.

 -- Flash Driver: tms470
     Most members of the TMS470 microcontroller family from Texas
     Instruments include internal flash and use ARM7TDMI cores.  This
     driver doesn't require the chip and bus width to be specified.

     Some tms470-specific commands are defined:

      -- Command: tms470 flash_keyset key0 key1 key2 key3
          Saves programming keys in a register, to enable flash erase
          and write commands.

      -- Command: tms470 osc_megahertz clock_mhz
          Reports the clock speed, which is used to calculate timings.

      -- Command: tms470 plldis (0|1)
          Disables (1) or enables (0) use of the PLL to speed up the
          flash clock.

 -- Flash Driver: w600
     W60x series Wi-Fi SoC from WinnerMicro are designed with ARM
     Cortex-M3 and have 1M Byte QFLASH inside.  The W600 driver uses the
     TARGET parameter to select the correct bank config.

          flash bank $_FLASHNAME w600 0x08000000 0 0 0 $_TARGETNAMEs

 -- Flash Driver: xmc1xxx
     All members of the XMC1xxx microcontroller family from Infineon.
     This driver does not require the chip and bus width to be
     specified.

 -- Flash Driver: xmc4xxx
     All members of the XMC4xxx microcontroller family from Infineon.
     This driver does not require the chip and bus width to be
     specified.

     Some xmc4xxx-specific commands are defined:

      -- Command: xmc4xxx flash_password bank_id passwd1 passwd2
          Saves flash protection passwords which are used to lock the
          user flash

      -- Command: xmc4xxx flash_unprotect bank_id user_level[0-1]
          Removes Flash write protection from the selected user bank

12.6 NAND Flash Commands
========================

Compared to NOR or SPI flash, NAND devices are inexpensive and high
density.  Today's NAND chips, and multi-chip modules, commonly hold
multiple GigaBytes of data.

NAND chips consist of a number of "erase blocks" of a given size (such
as 128 KBytes), each of which is divided into a number of pages (of
perhaps 512 or 2048 bytes each).  Each page of a NAND flash has an "out
of band" (OOB) area to hold Error Correcting Code (ECC) and other
metadata, usually 16 bytes of OOB for every 512 bytes of page data.

One key characteristic of NAND flash is that its error rate is higher
than that of NOR flash.  In normal operation, that ECC is used to
correct and detect errors.  However, NAND blocks can also wear out and
become unusable; those blocks are then marked "bad".  NAND chips are
even shipped from the manufacturer with a few bad blocks.  The highest
density chips use a technology (MLC) that wears out more quickly, so ECC
support is increasingly important as a way to detect blocks that have
begun to fail, and help to preserve data integrity with techniques such
as wear leveling.

Software is used to manage the ECC. Some controllers don't support ECC
directly; in those cases, software ECC is used.  Other controllers speed
up the ECC calculations with hardware.  Single-bit error correction
hardware is routine.  Controllers geared for newer MLC chips may correct
4 or more errors for every 512 bytes of data.

You will need to make sure that any data you write using OpenOCD
includes the appropriate kind of ECC. For example, that may mean passing
the 'oob_softecc' flag when writing NAND data, or ensuring that the
correct hardware ECC mode is used.

The basic steps for using NAND devices include:
  1. Declare via the command 'nand device'
     Do this in a board-specific configuration file, passing parameters
     as needed by the controller.
  2. Configure each device using 'nand probe'.
     Do this only after the associated target is set up, such as in its
     reset-init script or in procures defined to access that device.
  3. Operate on the flash via 'nand subcommand'
     Often commands to manipulate the flash are typed by a human, or run
     via a script in some automated way.  Common task include writing a
     boot loader, operating system, or other data needed to initialize
     or de-brick a board.

NOTE: At the time this text was written, the largest NAND flash fully
supported by OpenOCD is 2 GiBytes (16 GiBits).  This is because the
variables used to hold offsets and lengths are only 32 bits wide.
(Larger chips may work in some cases, unless an offset or length is
larger than 0xffffffff, the largest 32-bit unsigned integer.)  Some
larger devices will work, since they are actually multi-chip modules
with two smaller chips and individual chipselect lines.

12.6.1 NAND Configuration Commands
----------------------------------

NAND chips must be declared in configuration scripts, plus some
additional configuration that's done after OpenOCD has initialized.

 -- Config Command: nand device name driver target [configparams...]
     Declares a NAND device, which can be read and written to after it
     has been configured through 'nand probe'.  In OpenOCD, devices are
     single chips; this is unlike some operating systems, which may
     manage multiple chips as if they were a single (larger) device.  In
     some cases, configuring a device will activate extra commands; see
     the controller-specific documentation.

     NOTE: This command is not available after OpenOCD initialization
     has completed.  Use it in board specific configuration files, not
     interactively.

        * NAME ...  may be used to reference the NAND bank in most other
          NAND commands.  A number is also available.
        * DRIVER ...  identifies the NAND controller driver associated
          with the NAND device being declared.  *Note NAND Driver List:
          nanddriverlist.
        * TARGET ...  names the target used when issuing commands to the
          NAND controller.
        * CONFIGPARAMS ...  controllers may support, or require,
          additional parameters.  See the controller-specific
          documentation for more information.

 -- Command: nand list
     Prints a summary of each device declared using 'nand device',
     numbered from zero.  Note that un-probed devices show no details.
          > nand list
          #0: NAND 1GiB 3,3V 8-bit (Micron) pagesize: 2048, buswidth: 8,
                  blocksize: 131072, blocks: 8192
          #1: NAND 1GiB 3,3V 8-bit (Micron) pagesize: 2048, buswidth: 8,
                  blocksize: 131072, blocks: 8192
          >

 -- Command: nand probe num
     Probes the specified device to determine key characteristics like
     its page and block sizes, and how many blocks it has.  The NUM
     parameter is the value shown by 'nand list'.  You must
     (successfully) probe a device before you can use it with most other
     NAND commands.

12.6.2 Erasing, Reading, Writing to NAND Flash
----------------------------------------------

 -- Command: nand dump num filename offset length [oob_option]
     Reads binary data from the NAND device and writes it to the file,
     starting at the specified offset.  The NUM parameter is the value
     shown by 'nand list'.

     Use a complete path name for FILENAME, so you don't depend on the
     directory used to start the OpenOCD server.

     The OFFSET and LENGTH must be exact multiples of the device's page
     size.  They describe a data region; the OOB data associated with
     each such page may also be accessed.

     NOTE: At the time this text was written, no error correction was
     done on the data that's read, unless raw access was disabled and
     the underlying NAND controller driver had a 'read_page' method
     which handled that error correction.

     By default, only page data is saved to the specified file.  Use an
     OOB_OPTION parameter to save OOB data:
        * no oob_* parameter
          Output file holds only page data; OOB is discarded.
        * 'oob_raw'
          Output file interleaves page data and OOB data; the file will
          be longer than "length" by the size of the spare areas
          associated with each data page.  Note that this kind of "raw"
          access is different from what's implied by 'nand raw_access',
          which just controls whether a hardware-aware access method is
          used.
        * 'oob_only'
          Output file has only raw OOB data, and will be smaller than
          "length" since it will contain only the spare areas associated
          with each data page.

 -- Command: nand erase num [offset length]
     Erases blocks on the specified NAND device, starting at the
     specified OFFSET and continuing for LENGTH bytes.  Both of those
     values must be exact multiples of the device's block size, and the
     region they specify must fit entirely in the chip.  If those
     parameters are not specified, the whole NAND chip will be erased.
     The NUM parameter is the value shown by 'nand list'.

     NOTE: This command will try to erase bad blocks, when told to do
     so, which will probably invalidate the manufacturer's bad block
     marker.  For the remainder of the current server session, 'nand
     info' will still report that the block "is" bad.

 -- Command: nand write num filename offset [option...]
     Writes binary data from the file into the specified NAND device,
     starting at the specified offset.  Those pages should already have
     been erased; you can't change zero bits to one bits.  The NUM
     parameter is the value shown by 'nand list'.

     Use a complete path name for FILENAME, so you don't depend on the
     directory used to start the OpenOCD server.

     The OFFSET must be an exact multiple of the device's page size.
     All data in the file will be written, assuming it doesn't run past
     the end of the device.  Only full pages are written, and any extra
     space in the last page will be filled with 0xff bytes.  (That
     includes OOB data, if that's being written.)

     NOTE: At the time this text was written, bad blocks are ignored.
     That is, this routine will not skip bad blocks, but will instead
     try to write them.  This can cause problems.

     Provide at most one OPTION parameter.  With some NAND drivers, the
     meanings of these parameters may change if 'nand raw_access' was
     used to disable hardware ECC.
        * no oob_* parameter
          File has only page data, which is written.  If raw access is
          in use, the OOB area will not be written.  Otherwise, if the
          underlying NAND controller driver has a 'write_page' routine,
          that routine may write the OOB with hardware-computed ECC
          data.
        * 'oob_only'
          File has only raw OOB data, which is written to the OOB area.
          Each page's data area stays untouched.  This can be a
          dangerous option, since it can invalidate the ECC data.  You
          may need to force raw access to use this mode.
        * 'oob_raw'
          File interleaves data and OOB data, both of which are written
          If raw access is enabled, the data is written first, then the
          un-altered OOB. Otherwise, if the underlying NAND controller
          driver has a 'write_page' routine, that routine may modify the
          OOB before it's written, to include hardware-computed ECC
          data.
        * 'oob_softecc'
          File has only page data, which is written.  The OOB area is
          filled with 0xff, except for a standard 1-bit software ECC
          code stored in conventional locations.  You might need to
          force raw access to use this mode, to prevent the underlying
          driver from applying hardware ECC.
        * 'oob_softecc_kw'
          File has only page data, which is written.  The OOB area is
          filled with 0xff, except for a 4-bit software ECC specific to
          the boot ROM in Marvell Kirkwood SoCs.  You might need to
          force raw access to use this mode, to prevent the underlying
          driver from applying hardware ECC.

 -- Command: nand verify num filename offset [option...]
     Verify the binary data in the file has been programmed to the
     specified NAND device, starting at the specified offset.  The NUM
     parameter is the value shown by 'nand list'.

     Use a complete path name for FILENAME, so you don't depend on the
     directory used to start the OpenOCD server.

     The OFFSET must be an exact multiple of the device's page size.
     All data in the file will be read and compared to the contents of
     the flash, assuming it doesn't run past the end of the device.  As
     with 'nand write', only full pages are verified, so any extra space
     in the last page will be filled with 0xff bytes.

     The same OPTIONS accepted by 'nand write', and the file will be
     processed similarly to produce the buffers that can be compared
     against the contents produced from 'nand dump'.

     NOTE: This will not work when the underlying NAND controller
     driver's 'write_page' routine must update the OOB with a
     hardware-computed ECC before the data is written.  This limitation
     may be removed in a future release.

12.6.3 Other NAND commands
--------------------------

 -- Command: nand check_bad_blocks num [offset length]
     Checks for manufacturer bad block markers on the specified NAND
     device.  If no parameters are provided, checks the whole device;
     otherwise, starts at the specified OFFSET and continues for LENGTH
     bytes.  Both of those values must be exact multiples of the
     device's block size, and the region they specify must fit entirely
     in the chip.  The NUM parameter is the value shown by 'nand list'.

     NOTE: Before using this command you should force raw access with
     'nand raw_access enable' to ensure that the underlying driver will
     not try to apply hardware ECC.

 -- Command: nand info num
     The NUM parameter is the value shown by 'nand list'.  This prints
     the one-line summary from "nand list", plus for devices which have
     been probed this also prints any known status for each block.

 -- Command: nand raw_access num (enable|disable)
     Sets or clears an flag affecting how page I/O is done.  The NUM
     parameter is the value shown by 'nand list'.

     This flag is cleared (disabled) by default, but changing that value
     won't affect all NAND devices.  The key factor is whether the
     underlying driver provides 'read_page' or 'write_page' methods.  If
     it doesn't provide those methods, the setting of this flag is
     irrelevant; all access is effectively "raw".

     When those methods exist, they are normally used when reading data
     ('nand dump' or reading bad block markers) or writing it ('nand
     write').  However, enabling raw access (setting the flag) prevents
     use of those methods, bypassing hardware ECC logic.  This can be a
     dangerous option, since writing blocks with the wrong ECC data can
     cause them to be marked as bad.

12.6.4 NAND Driver List
-----------------------

As noted above, the 'nand device' command allows driver-specific options
and behaviors.  Some controllers also activate controller-specific
commands.

 -- NAND Driver: at91sam9
     This driver handles the NAND controllers found on AT91SAM9 family
     chips from Atmel.  It takes two extra parameters: address of the
     NAND chip; address of the ECC controller.
          nand device $NANDFLASH at91sam9 $CHIPNAME 0x40000000 0xfffffe800
     AT91SAM9 chips support single-bit ECC hardware.  The 'write_page'
     and 'read_page' methods are used to utilize the ECC hardware unless
     they are disabled by using the 'nand raw_access' command.  There
     are four additional commands that are needed to fully configure the
     AT91SAM9 NAND controller.  Two are optional; most boards use the
     same wiring for ALE/CLE:
      -- Config Command: at91sam9 cle num addr_line
          Configure the address line used for latching commands.  The
          NUM parameter is the value shown by 'nand list'.
      -- Config Command: at91sam9 ale num addr_line
          Configure the address line used for latching addresses.  The
          NUM parameter is the value shown by 'nand list'.

     For the next two commands, it is assumed that the pins have already
     been properly configured for input or output.
      -- Config Command: at91sam9 rdy_busy num pio_base_addr pin
          Configure the RDY/nBUSY input from the NAND device.  The NUM
          parameter is the value shown by 'nand list'.  PIO_BASE_ADDR is
          the base address of the PIO controller and PIN is the pin
          number.
      -- Config Command: at91sam9 ce num pio_base_addr pin
          Configure the chip enable input to the NAND device.  The NUM
          parameter is the value shown by 'nand list'.  PIO_BASE_ADDR is
          the base address of the PIO controller and PIN is the pin
          number.

 -- NAND Driver: davinci
     This driver handles the NAND controllers found on DaVinci family
     chips from Texas Instruments.  It takes three extra parameters:
     address of the NAND chip; hardware ECC mode to use ('hwecc1',
     'hwecc4', 'hwecc4_infix'); address of the AEMIF controller on this
     processor.
          nand device davinci dm355.arm 0x02000000 hwecc4 0x01e10000
     All DaVinci processors support the single-bit ECC hardware, and
     newer ones also support the four-bit ECC hardware.  The
     'write_page' and 'read_page' methods are used to implement those
     ECC modes, unless they are disabled using the 'nand raw_access'
     command.

 -- NAND Driver: lpc3180
     These controllers require an extra 'nand device' parameter: the
     clock rate used by the controller.
      -- Command: lpc3180 select num [mlc|slc]
          Configures use of the MLC or SLC controller mode.  MLC implies
          use of hardware ECC. The NUM parameter is the value shown by
          'nand list'.

     At this writing, this driver includes 'write_page' and 'read_page'
     methods.  Using 'nand raw_access' to disable those methods will
     prevent use of hardware ECC in the MLC controller mode, but won't
     change SLC behavior.

 -- NAND Driver: mx3
     This driver handles the NAND controller in i.MX31.  The mxc driver
     should work for this chip as well.

 -- NAND Driver: mxc
     This driver handles the NAND controller found in Freescale i.MX
     chips.  It has support for v1 (i.MX27 and i.MX31) and v2 (i.MX35).
     The driver takes 3 extra arguments, chip ('mx27', 'mx31', 'mx35'),
     ecc ('noecc', 'hwecc') and optionally if bad block information
     should be swapped between main area and spare area ('biswap'),
     defaults to off.
          nand device mx35.nand mxc imx35.cpu mx35 hwecc biswap
      -- Command: mxc biswap bank_num [enable|disable]
          Turns on/off bad block information swapping from main area,
          without parameter query status.

 -- NAND Driver: orion
     These controllers require an extra 'nand device' parameter: the
     address of the controller.
          nand device orion 0xd8000000
     These controllers don't define any specialized commands.  At this
     writing, their drivers don't include 'write_page' or 'read_page'
     methods, so 'nand raw_access' won't change any behavior.

 -- NAND Driver: s3c2410
 -- NAND Driver: s3c2412
 -- NAND Driver: s3c2440
 -- NAND Driver: s3c2443
 -- NAND Driver: s3c6400
     These S3C family controllers don't have any special 'nand device'
     options, and don't define any specialized commands.  At this
     writing, their drivers don't include 'write_page' or 'read_page'
     methods, so 'nand raw_access' won't change any behavior.

