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riscv-openocd/contrib/remote_bitbang/remote_bitbang_sysfsgpio.c

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// 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 "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>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#define LOG_ERROR(...) do { \
fprintf(stderr, __VA_ARGS__); \
fputc('\n', stderr); \
} while (0)
#define LOG_WARNING(...) LOG_ERROR(__VA_ARGS__)
#define ERROR_OK (-1)
#define ERROR_FAIL (-2)
#define ERROR_JTAG_INIT_FAILED ERROR_FAIL
/*
* Helper func to determine if gpio number valid
*
* Assume here that there will be less than 1000 gpios on a system
*/
static int is_gpio_valid(int gpio)
{
return gpio >= 0 && gpio < 1000;
}
/*
* Helper func to open, write to and close a file
* name and valstr must be null terminated.
*
* Returns negative on failure.
*/
static int open_write_close(const char *name, const char *valstr)
{
int ret;
int fd = open(name, O_WRONLY);
if (fd < 0)
return fd;
ret = write(fd, valstr, strlen(valstr));
close(fd);
return ret;
}
/*
* Helper func to unexport gpio from sysfs
*/
static void unexport_sysfs_gpio(int gpio)
{
char gpiostr[4];
if (!is_gpio_valid(gpio))
return;
snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
if (open_write_close("/sys/class/gpio/unexport", gpiostr) < 0)
LOG_ERROR("Couldn't unexport gpio %d", gpio);
return;
}
/*
* Exports and sets up direction for 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, int open_rw)
{
char buf[40];
char gpiostr[4];
int ret;
if (!is_gpio_valid(gpio))
return ERROR_OK;
snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
ret = open_write_close("/sys/class/gpio/export", gpiostr);
if (ret < 0) {
if (errno == EBUSY) {
LOG_WARNING("gpio %d is already exported", gpio);
} else {
LOG_ERROR("Couldn't export gpio %d", gpio);
perror("sysfsgpio: ");
return ERROR_FAIL;
}
}
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;
}
snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
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);
if (ret < 0)
unexport_sysfs_gpio(gpio);
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.
*/
static int tck_fd = -1;
static int tms_fd = -1;
static int tdi_fd = -1;
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
*
* 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_read(void)
{
char buf[1];
/* important to seek to signal sysfs of new read */
lseek(tdo_fd, 0, SEEK_SET);
int ret = read(tdo_fd, &buf, sizeof(buf));
if (ret < 0) {
LOG_WARNING("reading tdo failed");
return 0;
}
return buf[0];
}
/*
* Bitbang interface write of TCK, TMS, TDI
*
* 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";
size_t bytes_written;
if (!last_initialized) {
last_tck = !tck;
last_tms = !tms;
last_tdi = !tdi;
last_initialized = 1;
}
if (tdi != last_tdi) {
bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing tdi failed");
}
if (tms != last_tms) {
bytes_written = write(tms_fd, tms ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing tms failed");
}
/* write clk last */
if (tck != last_tck) {
bytes_written = write(tck_fd, tck ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing tck failed");
}
last_tdi = tdi;
last_tms = tms;
last_tck = tck;
}
/*
* Bitbang interface to manipulate reset lines SRST and TRST
*
* (1) assert or (0) deassert reset lines
*/
static void sysfsgpio_reset(int trst, int srst)
{
const char one[] = "1";
const char zero[] = "0";
size_t bytes_written;
/* assume active low */
if (srst_fd >= 0) {
bytes_written = write(srst_fd, srst ? &zero : &one, 1);
if (bytes_written != 1)
LOG_WARNING("writing srst failed");
}
/* assume active low */
if (trst_fd >= 0) {
bytes_written = write(trst_fd, trst ? &zero : &one, 1);
if (bytes_written != 1)
LOG_WARNING("writing trst failed");
}
}
/*
* 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)
{
if (gpio >= 0) {
if (fd >= 0)
close(fd);
unexport_sysfs_gpio(gpio);
}
}
static void cleanup_all_fds(void)
{
cleanup_fd(tck_fd, tck_gpio);
cleanup_fd(tms_fd, tms_gpio);
cleanup_fd(tdi_fd, tdi_gpio);
cleanup_fd(tdo_fd, tdo_gpio);
cleanup_fd(trst_fd, trst_gpio);
cleanup_fd(srst_fd, srst_gpio);
}
static void process_remote_protocol(void)
{
int c;
while (1) {
c = getchar();
if (c == EOF || c == 'Q') /* Quit */
break;
else if (c == 'b' || c == 'B') /* Blink */
continue;
else if (c >= 'r' && c <= 'r' + 3) { /* Reset */
char d = c - 'r';
sysfsgpio_reset(!!(d & 2),
(d & 1));
} 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+SWD driver\n");
for (int i = 1; i < argc; i++) {
if (!strcmp(argv[i], "tck"))
tck_gpio = atoi(argv[++i]);
else if (!strcmp(argv[i], "tms"))
tms_gpio = atoi(argv[++i]);
else if (!strcmp(argv[i], "tdo"))
tdo_gpio = atoi(argv[++i]);
else if (!strcmp(argv[i], "tdi"))
tdi_gpio = atoi(argv[++i]);
else if (!strcmp(argv[i], "trst"))
trst_gpio = atoi(argv[++i]);
else if (!strcmp(argv[i], "srst"))
srst_gpio = atoi(argv[++i]);
else {
LOG_ERROR("Usage:\n%s ((tck|tms|tdo|tdi|trst|srst) num)*", argv[0]);
return -1;
}
}
if (!(is_gpio_valid(tck_gpio)
&& is_gpio_valid(tms_gpio)
&& is_gpio_valid(tdi_gpio)
&& is_gpio_valid(tdo_gpio))) {
if (!is_gpio_valid(tck_gpio))
LOG_ERROR("gpio num for tck is invalid");
if (!is_gpio_valid(tms_gpio))
LOG_ERROR("gpio num for tms is invalid");
if (!is_gpio_valid(tdo_gpio))
LOG_ERROR("gpio num for tdo is invalid");
if (!is_gpio_valid(tdi_gpio))
LOG_ERROR("gpio num for tdi is invalid");
LOG_ERROR("Require tck, tms, tdi and tdo gpios to all be specified");
return ERROR_JTAG_INIT_FAILED;
}
/*
* 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, 0);
if (tck_fd < 0)
goto out_error;
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, 0);
if (tdi_fd < 0)
goto out_error;
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, 0);
if (trst_fd < 0)
goto out_error;
}
/* assume active low */
if (srst_gpio > 0) {
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);
LOG_WARNING("SysfsGPIO num: trst = %d", trst_gpio);
setvbuf(stdout, NULL, _IONBF, 0);
process_remote_protocol();
cleanup_all_fds();
return 0;
out_error:
cleanup_all_fds();
return ERROR_JTAG_INIT_FAILED;
}
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