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|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/***************************************************************************
* Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au *
***************************************************************************/
/* 2014-12: Addition of the SWD protocol support is based on the initial work
* on bcm2835gpio.c by Paul Fertser and modifications by Jean-Christian de Rivaz. */
/**
* @file
* This driver implements a bitbang jtag interface using gpio lines via
* sysfs.
* The aim of this driver implementation is use system GPIOs but avoid the
* need for a additional kernel driver.
* (Note memory mapped IO is another option, however it doesn't mix well with
* the kernel gpiolib driver - which makes sense I guess.)
*
* A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
* must be also be specified. The required jtag gpios are specified via the
* sysfsgpio_jtag_nums command or the relevant sysfsgpio_XXX_num commands.
* The srst and trst gpios are set via the sysfsgpio_srst_num and
* sysfsgpio_trst_num respectively. GPIO numbering follows the kernel
* convention of starting from 0.
*
* The gpios should not be in use by another entity, and must not be requested
* by a kernel driver without also being exported by it (otherwise they can't
* be exported by sysfs).
*
* The sysfs gpio interface can only manipulate one gpio at a time, so the
* bitbang write handler remembers the last state for tck, tms, tdi to avoid
* superfluous writes.
* For speed the sysfs "value" entry is opened at init and held open.
* This results in considerable gains over open-write-close (45s vs 900s)
*
* Further work could address:
* -srst and trst open drain/ push pull
* -configurable active high/low for srst & trst
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <helper/time_support.h>
#include <jtag/interface.h>
#include <transport/transport.h>
#include "bitbang.h"
/*
* Helper func to determine if gpio number valid
*
* Assume here that there will be less than 10000 gpios on a system
*/
static bool is_gpio_valid(int gpio)
{
return gpio >= 0 && gpio < 10000;
}
/*
* 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[5];
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);
}
/*
* Exports and sets up direction for gpio.
* If the gpio is an output, it is initialized according to init_high,
* otherwise it is ignored.
*
* 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)
{
struct timeval timeout, now;
char buf[40];
char gpiostr[5];
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);
LOG_ERROR("sysfsgpio: %s", strerror(errno));
return ERROR_FAIL;
}
}
gettimeofday(&timeout, NULL);
timeval_add_time(&timeout, 0, 500000);
snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
for (;;) {
ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
if (ret >= 0 || errno != EACCES)
break;
gettimeofday(&now, NULL);
if (timeval_compare(&now, &timeout) >= 0)
break;
jtag_sleep(10000);
}
if (ret < 0) {
LOG_ERROR("Couldn't set direction for gpio %d", gpio);
LOG_ERROR("sysfsgpio: %s", strerror(errno));
unexport_sysfs_gpio(gpio);
return ERROR_FAIL;
}
snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
for (;;) {
ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
if (ret >= 0 || errno != EACCES)
break;
gettimeofday(&now, NULL);
if (timeval_compare(&now, &timeout) >= 0)
break;
jtag_sleep(10000);
}
if (ret < 0) {
LOG_ERROR("Couldn't open value for gpio %d", gpio);
LOG_ERROR("sysfsgpio: %s", strerror(errno));
unexport_sysfs_gpio(gpio);
}
return ret;
}
/* 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;
static int swclk_gpio = -1;
static int swdio_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;
static int swclk_fd = -1;
static int swdio_fd = -1;
static int last_swclk;
static int last_swdio;
static bool last_stored;
static bool swdio_input;
static void sysfsgpio_swdio_drive(bool is_output)
{
char buf[40];
int ret;
snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
ret = open_write_close(buf, is_output ? "high" : "in");
if (ret < 0) {
LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
LOG_ERROR("sysfsgpio: %s", strerror(errno));
}
last_stored = false;
swdio_input = !is_output;
}
static int sysfsgpio_swdio_read(void)
{
char buf[1];
/* important to seek to signal sysfs of new read */
lseek(swdio_fd, 0, SEEK_SET);
int ret = read(swdio_fd, &buf, sizeof(buf));
if (ret < 0) {
LOG_WARNING("reading swdio failed");
return 0;
}
return buf[0] != '0';
}
static int sysfsgpio_swd_write(int swclk, int swdio)
{
const char one[] = "1";
const char zero[] = "0";
size_t bytes_written;
if (!swdio_input) {
if (!last_stored || (swdio != last_swdio)) {
bytes_written = write(swdio_fd, swdio ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing swdio failed");
}
}
/* write swclk last */
if (!last_stored || (swclk != last_swclk)) {
bytes_written = write(swclk_fd, swclk ? &one : &zero, 1);
if (bytes_written != 1)
LOG_WARNING("writing swclk failed");
}
last_swdio = swdio;
last_swclk = swclk;
last_stored = true;
return ERROR_OK;
}
/*
* 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 bb_value_t 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] == '0' ? BB_LOW : BB_HIGH;
}
/*
* 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.
*/
static int 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) {
last_tck = !tck;
last_tms = !tms;
last_tdi = !tdi;
first_time = 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;
return ERROR_OK;
}
/*
* Bitbang interface to manipulate reset lines SRST and TRST
*
* (1) assert or (0) deassert reset lines
*/
static int sysfsgpio_reset(int trst, int srst)
{
LOG_DEBUG("sysfsgpio_reset");
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");
}
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
{
if (CMD_ARGC == 4) {
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
} else if (CMD_ARGC != 0) {
return ERROR_COMMAND_SYNTAX_ERROR;
}
command_print(CMD,
"SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
{
if (CMD_ARGC == 2) {
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
} else if (CMD_ARGC != 0) {
return ERROR_COMMAND_SYNTAX_ERROR;
}
command_print(CMD,
"SysfsGPIO nums: swclk = %d, swdio = %d",
swclk_gpio, swdio_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
return ERROR_OK;
}
COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
{
if (CMD_ARGC == 1)
COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
return ERROR_OK;
}
static const struct command_registration sysfsgpio_subcommand_handlers[] = {
{
.name = "jtag_nums",
.handler = &sysfsgpio_handle_jtag_gpionums,
.mode = COMMAND_CONFIG,
.help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
.usage = "[tck tms tdi tdo]",
},
{
.name = "tck_num",
.handler = &sysfsgpio_handle_jtag_gpionum_tck,
.mode = COMMAND_CONFIG,
.help = "gpio number for tck.",
.usage = "[tck]",
},
{
.name = "tms_num",
.handler = &sysfsgpio_handle_jtag_gpionum_tms,
.mode = COMMAND_CONFIG,
.help = "gpio number for tms.",
.usage = "[tms]",
},
{
.name = "tdo_num",
.handler = &sysfsgpio_handle_jtag_gpionum_tdo,
.mode = COMMAND_CONFIG,
.help = "gpio number for tdo.",
.usage = "[tdo]",
},
{
.name = "tdi_num",
.handler = &sysfsgpio_handle_jtag_gpionum_tdi,
.mode = COMMAND_CONFIG,
.help = "gpio number for tdi.",
.usage = "[tdi]",
},
{
.name = "srst_num",
.handler = &sysfsgpio_handle_jtag_gpionum_srst,
.mode = COMMAND_CONFIG,
.help = "gpio number for srst.",
.usage = "[srst]",
},
{
.name = "trst_num",
.handler = &sysfsgpio_handle_jtag_gpionum_trst,
.mode = COMMAND_CONFIG,
.help = "gpio number for trst.",
.usage = "[trst]",
},
{
.name = "swd_nums",
.handler = &sysfsgpio_handle_swd_gpionums,
.mode = COMMAND_CONFIG,
.help = "gpio numbers for swclk, swdio. (in that order)",
.usage = "[swclk swdio]",
},
{
.name = "swclk_num",
.handler = &sysfsgpio_handle_swd_gpionum_swclk,
.mode = COMMAND_CONFIG,
.help = "gpio number for swclk.",
.usage = "[swclk]",
},
{
.name = "swdio_num",
.handler = &sysfsgpio_handle_swd_gpionum_swdio,
.mode = COMMAND_CONFIG,
.help = "gpio number for swdio.",
.usage = "[swdio]",
},
COMMAND_REGISTRATION_DONE
};
static const struct command_registration sysfsgpio_command_handlers[] = {
{
.name = "sysfsgpio",
.mode = COMMAND_ANY,
.help = "perform sysfsgpio management",
.chain = sysfsgpio_subcommand_handlers,
.usage = "",
},
COMMAND_REGISTRATION_DONE
};
static int sysfsgpio_init(void);
static int sysfsgpio_quit(void);
static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
static struct jtag_interface sysfsgpio_interface = {
.supported = DEBUG_CAP_TMS_SEQ,
.execute_queue = bitbang_execute_queue,
};
struct adapter_driver sysfsgpio_adapter_driver = {
.name = "sysfsgpio",
.transports = sysfsgpio_transports,
.commands = sysfsgpio_command_handlers,
.init = sysfsgpio_init,
.quit = sysfsgpio_quit,
.reset = sysfsgpio_reset,
.jtag_ops = &sysfsgpio_interface,
.swd_ops = &bitbang_swd,
};
static struct bitbang_interface sysfsgpio_bitbang = {
.read = sysfsgpio_read,
.write = sysfsgpio_write,
.swdio_read = sysfsgpio_swdio_read,
.swdio_drive = sysfsgpio_swdio_drive,
.swd_write = sysfsgpio_swd_write,
.blink = 0
};
/* 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)
{
if (transport_is_jtag()) {
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);
}
if (transport_is_swd()) {
cleanup_fd(swclk_fd, swclk_gpio);
cleanup_fd(swdio_fd, swdio_gpio);
}
cleanup_fd(srst_fd, srst_gpio);
}
static bool sysfsgpio_jtag_mode_possible(void)
{
if (!is_gpio_valid(tck_gpio))
return false;
if (!is_gpio_valid(tms_gpio))
return false;
if (!is_gpio_valid(tdi_gpio))
return false;
if (!is_gpio_valid(tdo_gpio))
return false;
return true;
}
static bool sysfsgpio_swd_mode_possible(void)
{
if (!is_gpio_valid(swclk_gpio))
return false;
if (!is_gpio_valid(swdio_gpio))
return false;
return true;
}
static int sysfsgpio_init(void)
{
bitbang_interface = &sysfsgpio_bitbang;
LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
/*
* Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
* as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
* For SWD, SWCLK and SWDIO are configures as output high.
*/
if (transport_is_jtag()) {
if (!sysfsgpio_jtag_mode_possible()) {
LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode");
return ERROR_JTAG_INIT_FAILED;
}
tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
if (tck_fd < 0)
goto out_error;
tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
if (tms_fd < 0)
goto out_error;
tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
if (tdi_fd < 0)
goto out_error;
tdo_fd = setup_sysfs_gpio(tdo_gpio, 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);
if (trst_fd < 0)
goto out_error;
}
}
if (transport_is_swd()) {
if (!sysfsgpio_swd_mode_possible()) {
LOG_ERROR("Require swclk and swdio gpio for SWD mode");
return ERROR_JTAG_INIT_FAILED;
}
swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
if (swclk_fd < 0)
goto out_error;
swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
if (swdio_fd < 0)
goto out_error;
}
/* assume active low*/
if (srst_gpio >= 0) {
srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
if (srst_fd < 0)
goto out_error;
}
return ERROR_OK;
out_error:
cleanup_all_fds();
return ERROR_JTAG_INIT_FAILED;
}
static int sysfsgpio_quit(void)
{
cleanup_all_fds();
return ERROR_OK;
}
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