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remote_bitbang: Add SWD support
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This adds new command characters to make SWD work with the new split
jtag and swd operations of bitbang.

The command characters are as follows:
    O - SWDIO drive 1
    o - SWDIO drive 0
    c - SWDIO read request
    d - SWD write 0 0
    e - SWD write 0 1
    f - SWD write 1 0
    g - SWD write 1 1

Documentation has been updated accordingly. The new commands will be
used by an adapted version of the jtag-openocd applet of the "Glasgow
Debug Tool" (https://github.com/glasgowEmbedded/Glasgow). It has been
tested against an stm32f103 and an at91samd21 target.

contrib/remote/bitbang/remote_bitbang_sysfsgpio.c has also been adapted
to support SWD via the new command set. Some limited testing has been
done using a Raspberry Pi 2 with an stm32f103 and an at91samd21 target
attached.

Change-Id: I8e998a2cb36905142cb16e534483094cd99e8fa7
Signed-off-by: Manuel Wick <manuel@matronix.de>
Signed-off-by: David Ryskalczyk <david.rysk@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6044
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
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@mwick83 @tom-van
mwick83 authored and tom-van committed Dec 3, 2023
1 parent 119a533 commit 0f70c6c
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Showing 5 changed files with 230 additions and 60 deletions.
6 changes: 3 additions & 3 deletions configure.ac
View file
Original file line number Diff line number Diff line change
Expand Up @@ -382,7 +382,7 @@ AC_ARG_ENABLE([internal-libjaylink],
[use_internal_libjaylink=$enableval], [use_internal_libjaylink=no])

AC_ARG_ENABLE([remote-bitbang],
AS_HELP_STRING([--enable-remote-bitbang], [Enable building support for the Remote Bitbang jtag driver]),
AS_HELP_STRING([--enable-remote-bitbang], [Enable building support for the Remote Bitbang driver]),
[build_remote_bitbang=$enableval], [build_remote_bitbang=no])

AS_CASE(["${host_cpu}"],
Expand Down Expand Up @@ -598,9 +598,9 @@ AS_IF([test "x$use_internal_jimtcl" = "xyes"], [

AS_IF([test "x$build_remote_bitbang" = "xyes"], [
build_bitbang=yes
AC_DEFINE([BUILD_REMOTE_BITBANG], [1], [1 if you want the Remote Bitbang JTAG driver.])
AC_DEFINE([BUILD_REMOTE_BITBANG], [1], [1 if you want the Remote Bitbang driver.])
], [
AC_DEFINE([BUILD_REMOTE_BITBANG], [0], [0 if you don't want the Remote Bitbang JTAG driver.])
AC_DEFINE([BUILD_REMOTE_BITBANG], [0], [0 if you don't want the Remote Bitbang driver.])
])

AS_IF([test "x$build_sysfsgpio" = "xyes"], [
Expand Down
211 changes: 166 additions & 45 deletions contrib/remote_bitbang/remote_bitbang_sysfsgpio.c
View file
Original file line number Diff line number Diff line change
@@ -1,30 +1,31 @@
// SPDX-License-Identifier: GPL-2.0-or-later

/***************************************************************************
* Copyright (C) 2021 by Manuel Wick <manuel@matronix.de> *
* Copyright (C) 2013 Paul Fertser <fercerpav@gmail.com> *
* Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au *
***************************************************************************/

/*
This is a test application to be used as a remote bitbang server for
the OpenOCD remote_bitbang interface driver.
To compile run:
gcc -Wall -ansi -pedantic -std=c99 -o remote_bitbang_sysfsgpio remote_bitbang_sysfsgpio.c
Usage example:
On Raspberry Pi run:
socat TCP6-LISTEN:7777,fork EXEC:"sudo ./remote_bitbang_sysfsgpio tck 11 tms 25 tdo 9 tdi 10"
On host run:
openocd -c "interface remote_bitbang; remote_bitbang host raspberrypi; remote_bitbang port 7777" \
-f target/stm32f1x.cfg
Or if you want to test UNIX sockets, run both on Raspberry Pi:
socat UNIX-LISTEN:/tmp/remotebitbang-socket,fork EXEC:"sudo ./remote_bitbang_sysfsgpio tck 11 tms 25 tdo 9 tdi 10"
openocd -c "interface remote_bitbang; remote_bitbang host /tmp/remotebitbang-socket" -f target/stm32f1x.cfg
* This is a test application to be used as a remote bitbang server for
* the OpenOCD remote_bitbang interface driver.
*
* To compile run:
* gcc -Wall -ansi -pedantic -std=c99 -o remote_bitbang_sysfsgpio remote_bitbang_sysfsgpio.c
*
*
* Usage example:
*
* On Raspberry Pi run:
* socat TCP6-LISTEN:7777,fork EXEC:"sudo ./remote_bitbang_sysfsgpio tck 11 tms 25 tdo 9 tdi 10"
*
* On host run:
* openocd -c "adapter driver remote_bitbang; remote_bitbang host raspberrypi; remote_bitbang port 7777" \
* -f target/stm32f1x.cfg
*
* Or if you want to test UNIX sockets, run both on Raspberry Pi:
* socat UNIX-LISTEN:/tmp/remotebitbang-socket,fork EXEC:"sudo ./remote_bitbang_sysfsgpio tck 11 tms 25 tdo 9 tdi 10"
* openocd -c "adapter driver remote_bitbang; remote_bitbang host /tmp/remotebitbang-socket" -f target/stm32f1x.cfg
*/

#include <sys/types.h>
Expand Down Expand Up @@ -97,11 +98,14 @@ static void unexport_sysfs_gpio(int gpio)
* If the gpio is an output, it is initialized according to init_high,
* otherwise it is ignored.
*
* When open_rw is set, the file descriptor will be open as read and write,
* e.g. for SWDIO (TMS) that is used as input and output.
*
* If the gpio is already exported we just show a warning and continue; if
* openocd happened to crash (or was killed by user) then the gpios will not
* have been cleaned up.
*/
static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
static int setup_sysfs_gpio(int gpio, int is_output, int init_high, int open_rw)
{
char buf[40];
char gpiostr[4];
Expand Down Expand Up @@ -132,7 +136,9 @@ static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
}

snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
if (is_output)
if (open_rw)
ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
else if (is_output)
ret = open(buf, O_WRONLY | O_NONBLOCK | O_SYNC);
else
ret = open(buf, O_RDONLY | O_NONBLOCK | O_SYNC);
Expand All @@ -143,6 +149,37 @@ static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
return ret;
}

/*
* Change direction for gpio.
*/
static int change_dir_sysfs_gpio(int gpio, int is_output, int init_high)
{
char buf[40];
int ret;

if (!is_gpio_valid(gpio))
return ERROR_OK;

snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
if (ret < 0) {
LOG_ERROR("Couldn't set direction for gpio %d", gpio);
perror("sysfsgpio: ");
unexport_sysfs_gpio(gpio);
return ERROR_FAIL;
}

return ERROR_OK;
}

/* gpio numbers for each gpio. Negative values are invalid */
static int tck_gpio = -1;
static int tms_gpio = -1;
static int tdi_gpio = -1;
static int tdo_gpio = -1;
static int trst_gpio = -1;
static int srst_gpio = -1;

/*
* file descriptors for /sys/class/gpio/gpioXX/value
* Set up during init.
Expand All @@ -154,6 +191,15 @@ static int tdo_fd = -1;
static int trst_fd = -1;
static int srst_fd = -1;

/*
* GPIO state of /sys/class/gpio/gpioXX/value
*/
static int last_tck = -1;
static int last_tms = -1;
static int last_tms_drive = -1;
static int last_tdi = -1;
static int last_initialized = -1;

/*
* Bitbang interface read of TDO
*
Expand All @@ -179,26 +225,22 @@ static int sysfsgpio_read(void)
/*
* Bitbang interface write of TCK, TMS, TDI
*
* Seeing as this is the only function where the outputs are changed,
* we can cache the old value to avoid needlessly writing it.
* Output states are changed here and in sysfsgpio_write_swd,
* which are not used simultaneously, so we can cache the old
* value to avoid needlessly writing it.
*/
static void sysfsgpio_write(int tck, int tms, int tdi)
{
const char one[] = "1";
const char zero[] = "0";

static int last_tck;
static int last_tms;
static int last_tdi;

static int first_time;
size_t bytes_written;

if (!first_time) {
if (!last_initialized) {
last_tck = !tck;
last_tms = !tms;
last_tdi = !tdi;
first_time = 1;
last_initialized = 1;
}

if (tdi != last_tdi) {
Expand Down Expand Up @@ -251,13 +293,81 @@ static void sysfsgpio_reset(int trst, int srst)
}
}

/* gpio numbers for each gpio. Negative values are invalid */
static int tck_gpio = -1;
static int tms_gpio = -1;
static int tdi_gpio = -1;
static int tdo_gpio = -1;
static int trst_gpio = -1;
static int srst_gpio = -1;
/*
* Bitbang interface set direction of SWDIO (TMS)
*/
static void sysfsgpio_swdio_drive(int is_output)
{
int ret;

if (is_output != 0 && last_tms == -1)
last_tms = 0;

ret = change_dir_sysfs_gpio(tms_gpio, (is_output != 0) ? 1 : 0, last_tms);
if (ret != ERROR_OK)
LOG_WARNING("Failed to change SWDIO (TMS) direction to output");
else
last_tms_drive = (is_output != 0) ? 1 : 0;
}

/*
* Bitbang interface read of SWDIO (TMS)
*
* The sysfs value will read back either '0' or '1'. The trick here is to call
* lseek to bypass buffering in the sysfs kernel driver.
*/
static int sysfsgpio_swdio_read(void)
{
char buf[1];

/* important to seek to signal sysfs of new read */
lseek(tms_fd, 0, SEEK_SET);
int ret = read(tms_fd, &buf, sizeof(buf));

if (ret < 0) {
LOG_WARNING("reading swdio (tms) failed");
return 0;
}

return buf[0];
}

/*
* Bitbang interface write of SWCLK (TCK) and SWDIO (TMS)
*
* Output states are changed here and in sysfsgpio_write, which
* are not used simultaneously, so we can cache the old value
* to avoid needlessly writing it.
*/
static void sysfsgpio_swd_write(int swclk, int swdio)
{
static const char one[] = "1";
static const char zero[] = "0";

size_t bytes_written;

if (!last_initialized) {
last_tck = !swclk;
last_tms = !swdio;
last_initialized = 1;
}

if (last_tms_drive == 1 && swdio != last_tms) {
bytes_written = write(tms_fd, swdio ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing swdio (tms) failed");
}

/* write clk last */
if (swclk != last_tck) {
bytes_written = write(tck_fd, swclk ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing swclk (tck) failed");
}

last_tms = swdio;
last_tck = swclk;
}

/* helper func to close and cleanup files only if they were valid/ used */
static void cleanup_fd(int fd, int gpio)
Expand Down Expand Up @@ -293,21 +403,29 @@ static void process_remote_protocol(void)
char d = c - 'r';
sysfsgpio_reset(!!(d & 2),
(d & 1));
} else if (c >= '0' && c <= '0' + 7) {/* Write */
} else if (c >= '0' && c <= '0' + 7) { /* Write */
char d = c - '0';
sysfsgpio_write(!!(d & 4),
!!(d & 2),
(d & 1));
} else if (c == 'R')
putchar(sysfsgpio_read());
else if (c == 'c') /* SWDIO read */
putchar(sysfsgpio_swdio_read());
else if (c == 'o' || c == 'O') /* SWDIO drive */
sysfsgpio_swdio_drive(c == 'o' ? 0 : 1);
else if (c >= 'd' && c <= 'g') { /* SWD write */
char d = c - 'd';
sysfsgpio_swd_write((d & 2), (d & 1));
}
else
LOG_ERROR("Unknown command '%c' received", c);
}
}

int main(int argc, char *argv[])
{
LOG_WARNING("SysfsGPIO remote_bitbang JTAG driver\n");
LOG_WARNING("SysfsGPIO remote_bitbang JTAG+SWD driver\n");

for (int i = 1; i < argc; i++) {
if (!strcmp(argv[i], "tck"))
Expand Down Expand Up @@ -349,36 +467,39 @@ int main(int argc, char *argv[])
* Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
* as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
*/
tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0, 0);
if (tck_fd < 0)
goto out_error;

tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1, 1);
if (tms_fd < 0)
goto out_error;
last_tms_drive = 0;

tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0, 0);
if (tdi_fd < 0)
goto out_error;

tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0, 0);
if (tdo_fd < 0)
goto out_error;

/* assume active low */
if (trst_gpio > 0) {
trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1, 0);
if (trst_fd < 0)
goto out_error;
}

/* assume active low */
if (srst_gpio > 0) {
srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1, 0);
if (srst_fd < 0)
goto out_error;
}

last_initialized = 0;

LOG_WARNING("SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
LOG_WARNING("SysfsGPIO num: srst = %d", srst_gpio);
Expand Down
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