1 /***************************************************************************
2 * Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au *
4 * This program is free software; you can redistribute it and/or modify *
5 * it under the terms of the GNU General Public License as published by *
6 * the Free Software Foundation; either version 2 of the License, or *
7 * (at your option) any later version. *
9 * This program is distributed in the hope that it will be useful, *
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
12 * GNU General Public License for more details. *
14 * You should have received a copy of the GNU General Public License *
15 * along with this program. If not, see <http://www.gnu.org/licenses/>. *
16 ***************************************************************************/
18 /* 2014-12: Addition of the SWD protocol support is based on the initial work
19 * on bcm2835gpio.c by Paul Fertser and modifications by Jean-Christian de Rivaz. */
23 * This driver implements a bitbang jtag interface using gpio lines via
25 * The aim of this driver implementation is use system GPIOs but avoid the
26 * need for a additional kernel driver.
27 * (Note memory mapped IO is another option, however it doesn't mix well with
28 * the kernel gpiolib driver - which makes sense I guess.)
30 * A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
31 * must be also be specified. The required jtag gpios are specified via the
32 * sysfsgpio_jtag_nums command or the relevant sysfsgpio_XXX_num commang.
33 * The srst and trst gpios are set via the sysfsgpio_srst_num and
34 * sysfsgpio_trst_num respectively. GPIO numbering follows the kernel
35 * convention of starting from 0.
37 * The gpios should not be in use by another entity, and must not be requested
38 * by a kernel driver without also being exported by it (otherwise they can't
39 * be exported by sysfs).
41 * The sysfs gpio interface can only manipulate one gpio at a time, so the
42 * bitbang write handler remembers the last state for tck, tms, tdi to avoid
44 * For speed the sysfs "value" entry is opened at init and held open.
45 * This results in considerable gains over open-write-close (45s vs 900s)
47 * Further work could address:
48 * -srst and trst open drain/ push pull
49 * -configurable active high/low for srst & trst
55 #include <helper/time_support.h>
56 #include <jtag/interface.h>
60 * Helper func to determine if gpio number valid
62 * Assume here that there will be less than 10000 gpios on a system
64 static bool is_gpio_valid(int gpio)
66 return gpio >= 0 && gpio < 10000;
70 * Helper func to open, write to and close a file
71 * name and valstr must be null terminated.
73 * Returns negative on failure.
75 static int open_write_close(const char *name, const char *valstr)
78 int fd = open(name, O_WRONLY);
82 ret = write(fd, valstr, strlen(valstr));
89 * Helper func to unexport gpio from sysfs
91 static void unexport_sysfs_gpio(int gpio)
95 if (!is_gpio_valid(gpio))
98 snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
99 if (open_write_close("/sys/class/gpio/unexport", gpiostr) < 0)
100 LOG_ERROR("Couldn't unexport gpio %d", gpio);
106 * Exports and sets up direction for gpio.
107 * If the gpio is an output, it is initialized according to init_high,
108 * otherwise it is ignored.
110 * If the gpio is already exported we just show a warning and continue; if
111 * openocd happened to crash (or was killed by user) then the gpios will not
112 * have been cleaned up.
114 static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
116 struct timeval timeout, now;
121 if (!is_gpio_valid(gpio))
124 snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
125 ret = open_write_close("/sys/class/gpio/export", gpiostr);
127 if (errno == EBUSY) {
128 LOG_WARNING("gpio %d is already exported", gpio);
130 LOG_ERROR("Couldn't export gpio %d", gpio);
131 perror("sysfsgpio: ");
136 gettimeofday(&timeout, NULL);
137 timeval_add_time(&timeout, 0, 500000);
139 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
141 ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
142 if (ret >= 0 || errno != EACCES)
144 gettimeofday(&now, NULL);
145 if (timeval_compare(&now, &timeout) >= 0)
150 LOG_ERROR("Couldn't set direction for gpio %d", gpio);
151 perror("sysfsgpio: ");
152 unexport_sysfs_gpio(gpio);
156 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
158 ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
159 if (ret >= 0 || errno != EACCES)
161 gettimeofday(&now, NULL);
162 if (timeval_compare(&now, &timeout) >= 0)
167 LOG_ERROR("Couldn't open value for gpio %d", gpio);
168 perror("sysfsgpio: ");
169 unexport_sysfs_gpio(gpio);
175 /* gpio numbers for each gpio. Negative values are invalid */
176 static int tck_gpio = -1;
177 static int tms_gpio = -1;
178 static int tdi_gpio = -1;
179 static int tdo_gpio = -1;
180 static int trst_gpio = -1;
181 static int srst_gpio = -1;
182 static int swclk_gpio = -1;
183 static int swdio_gpio = -1;
186 * file descriptors for /sys/class/gpio/gpioXX/value
187 * Set up during init.
189 static int tck_fd = -1;
190 static int tms_fd = -1;
191 static int tdi_fd = -1;
192 static int tdo_fd = -1;
193 static int trst_fd = -1;
194 static int srst_fd = -1;
195 static int swclk_fd = -1;
196 static int swdio_fd = -1;
198 static int last_swclk;
199 static int last_swdio;
200 static bool last_stored;
201 static bool swdio_input;
203 static void sysfsgpio_swdio_drive(bool is_output)
208 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
209 ret = open_write_close(buf, is_output ? "high" : "in");
211 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
212 perror("sysfsgpio: ");
216 swdio_input = !is_output;
219 static int sysfsgpio_swdio_read(void)
223 /* important to seek to signal sysfs of new read */
224 lseek(swdio_fd, 0, SEEK_SET);
225 int ret = read(swdio_fd, &buf, sizeof(buf));
228 LOG_WARNING("reading swdio failed");
232 return buf[0] != '0';
235 static void sysfsgpio_swdio_write(int swclk, int swdio)
237 const char one[] = "1";
238 const char zero[] = "0";
240 size_t bytes_written;
243 if (!last_stored || (swdio != last_swdio)) {
244 bytes_written = write(swdio_fd, swdio ? &one : &zero, 1);
245 if (bytes_written != 1)
246 LOG_WARNING("writing swdio failed");
250 /* write swclk last */
251 if (!last_stored || (swclk != last_swclk)) {
252 bytes_written = write(swclk_fd, swclk ? &one : &zero, 1);
253 if (bytes_written != 1)
254 LOG_WARNING("writing swclk failed");
263 * Bitbang interface read of TDO
265 * The sysfs value will read back either '0' or '1'. The trick here is to call
266 * lseek to bypass buffering in the sysfs kernel driver.
268 static bb_value_t sysfsgpio_read(void)
272 /* important to seek to signal sysfs of new read */
273 lseek(tdo_fd, 0, SEEK_SET);
274 int ret = read(tdo_fd, &buf, sizeof(buf));
277 LOG_WARNING("reading tdo failed");
281 return buf[0] == '0' ? BB_LOW : BB_HIGH;
285 * Bitbang interface write of TCK, TMS, TDI
287 * Seeing as this is the only function where the outputs are changed,
288 * we can cache the old value to avoid needlessly writing it.
290 static int sysfsgpio_write(int tck, int tms, int tdi)
293 sysfsgpio_swdio_write(tck, tdi);
297 const char one[] = "1";
298 const char zero[] = "0";
304 static int first_time;
305 size_t bytes_written;
314 if (tdi != last_tdi) {
315 bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
316 if (bytes_written != 1)
317 LOG_WARNING("writing tdi failed");
320 if (tms != last_tms) {
321 bytes_written = write(tms_fd, tms ? &one : &zero, 1);
322 if (bytes_written != 1)
323 LOG_WARNING("writing tms failed");
327 if (tck != last_tck) {
328 bytes_written = write(tck_fd, tck ? &one : &zero, 1);
329 if (bytes_written != 1)
330 LOG_WARNING("writing tck failed");
341 * Bitbang interface to manipulate reset lines SRST and TRST
343 * (1) assert or (0) deassert reset lines
345 static int sysfsgpio_reset(int trst, int srst)
347 LOG_DEBUG("sysfsgpio_reset");
348 const char one[] = "1";
349 const char zero[] = "0";
350 size_t bytes_written;
352 /* assume active low */
354 bytes_written = write(srst_fd, srst ? &zero : &one, 1);
355 if (bytes_written != 1)
356 LOG_WARNING("writing srst failed");
359 /* assume active low */
361 bytes_written = write(trst_fd, trst ? &zero : &one, 1);
362 if (bytes_written != 1)
363 LOG_WARNING("writing trst failed");
369 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
372 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
373 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
374 COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
375 COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
376 } else if (CMD_ARGC != 0) {
377 return ERROR_COMMAND_SYNTAX_ERROR;
381 "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
382 tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
387 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
390 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
392 command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
396 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
399 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
401 command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
405 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
408 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
410 command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
414 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
417 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
419 command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
423 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
426 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
428 command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
432 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
435 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
437 command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
441 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
444 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
445 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
446 } else if (CMD_ARGC != 0) {
447 return ERROR_COMMAND_SYNTAX_ERROR;
451 "SysfsGPIO nums: swclk = %d, swdio = %d",
452 swclk_gpio, swdio_gpio);
457 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
460 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
462 command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
466 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
469 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
471 command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
475 static const struct command_registration sysfsgpio_command_handlers[] = {
477 .name = "sysfsgpio_jtag_nums",
478 .handler = &sysfsgpio_handle_jtag_gpionums,
479 .mode = COMMAND_CONFIG,
480 .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
481 .usage = "[tck tms tdi tdo]",
484 .name = "sysfsgpio_tck_num",
485 .handler = &sysfsgpio_handle_jtag_gpionum_tck,
486 .mode = COMMAND_CONFIG,
487 .help = "gpio number for tck.",
491 .name = "sysfsgpio_tms_num",
492 .handler = &sysfsgpio_handle_jtag_gpionum_tms,
493 .mode = COMMAND_CONFIG,
494 .help = "gpio number for tms.",
498 .name = "sysfsgpio_tdo_num",
499 .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
500 .mode = COMMAND_CONFIG,
501 .help = "gpio number for tdo.",
505 .name = "sysfsgpio_tdi_num",
506 .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
507 .mode = COMMAND_CONFIG,
508 .help = "gpio number for tdi.",
512 .name = "sysfsgpio_srst_num",
513 .handler = &sysfsgpio_handle_jtag_gpionum_srst,
514 .mode = COMMAND_CONFIG,
515 .help = "gpio number for srst.",
519 .name = "sysfsgpio_trst_num",
520 .handler = &sysfsgpio_handle_jtag_gpionum_trst,
521 .mode = COMMAND_CONFIG,
522 .help = "gpio number for trst.",
526 .name = "sysfsgpio_swd_nums",
527 .handler = &sysfsgpio_handle_swd_gpionums,
528 .mode = COMMAND_CONFIG,
529 .help = "gpio numbers for swclk, swdio. (in that order)",
530 .usage = "[swclk swdio]",
533 .name = "sysfsgpio_swclk_num",
534 .handler = &sysfsgpio_handle_swd_gpionum_swclk,
535 .mode = COMMAND_CONFIG,
536 .help = "gpio number for swclk.",
540 .name = "sysfsgpio_swdio_num",
541 .handler = &sysfsgpio_handle_swd_gpionum_swdio,
542 .mode = COMMAND_CONFIG,
543 .help = "gpio number for swdio.",
546 COMMAND_REGISTRATION_DONE
549 static int sysfsgpio_init(void);
550 static int sysfsgpio_quit(void);
552 static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
554 static struct jtag_interface sysfsgpio_interface = {
555 .supported = DEBUG_CAP_TMS_SEQ,
556 .execute_queue = bitbang_execute_queue,
559 struct adapter_driver sysfsgpio_adapter_driver = {
561 .transports = sysfsgpio_transports,
562 .commands = sysfsgpio_command_handlers,
564 .init = sysfsgpio_init,
565 .quit = sysfsgpio_quit,
566 .reset = sysfsgpio_reset,
568 .jtag_ops = &sysfsgpio_interface,
569 .swd_ops = &bitbang_swd,
572 static struct bitbang_interface sysfsgpio_bitbang = {
573 .read = sysfsgpio_read,
574 .write = sysfsgpio_write,
575 .swdio_read = sysfsgpio_swdio_read,
576 .swdio_drive = sysfsgpio_swdio_drive,
580 /* helper func to close and cleanup files only if they were valid/ used */
581 static void cleanup_fd(int fd, int gpio)
587 unexport_sysfs_gpio(gpio);
591 static void cleanup_all_fds(void)
593 cleanup_fd(tck_fd, tck_gpio);
594 cleanup_fd(tms_fd, tms_gpio);
595 cleanup_fd(tdi_fd, tdi_gpio);
596 cleanup_fd(tdo_fd, tdo_gpio);
597 cleanup_fd(trst_fd, trst_gpio);
598 cleanup_fd(srst_fd, srst_gpio);
599 cleanup_fd(swclk_fd, swclk_gpio);
600 cleanup_fd(swdio_fd, swdio_gpio);
603 static bool sysfsgpio_jtag_mode_possible(void)
605 if (!is_gpio_valid(tck_gpio))
607 if (!is_gpio_valid(tms_gpio))
609 if (!is_gpio_valid(tdi_gpio))
611 if (!is_gpio_valid(tdo_gpio))
616 static bool sysfsgpio_swd_mode_possible(void)
618 if (!is_gpio_valid(swclk_gpio))
620 if (!is_gpio_valid(swdio_gpio))
625 static int sysfsgpio_init(void)
627 bitbang_interface = &sysfsgpio_bitbang;
629 LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
631 if (sysfsgpio_jtag_mode_possible()) {
632 if (sysfsgpio_swd_mode_possible())
633 LOG_INFO("JTAG and SWD modes enabled");
635 LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
636 } else if (sysfsgpio_swd_mode_possible()) {
637 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
639 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
640 return ERROR_JTAG_INIT_FAILED;
645 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
646 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
647 * For SWD, SWCLK and SWDIO are configures as output high.
650 tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
656 tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
662 tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
668 tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
673 /* assume active low*/
674 if (trst_gpio >= 0) {
675 trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
680 /* assume active low*/
681 if (srst_gpio >= 0) {
682 srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
687 if (swclk_gpio >= 0) {
688 swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
693 if (swdio_gpio >= 0) {
694 swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
699 if (sysfsgpio_swd_mode_possible()) {
701 bitbang_swd_switch_seq(JTAG_TO_SWD);
703 bitbang_swd_switch_seq(SWD_TO_JTAG);
710 return ERROR_JTAG_INIT_FAILED;
713 static int sysfsgpio_quit(void)