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 commands.
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>
57 #include <transport/transport.h>
61 * Helper func to determine if gpio number valid
63 * Assume here that there will be less than 10000 gpios on a system
65 static bool is_gpio_valid(int gpio)
67 return gpio >= 0 && gpio < 10000;
71 * Helper func to open, write to and close a file
72 * name and valstr must be null terminated.
74 * Returns negative on failure.
76 static int open_write_close(const char *name, const char *valstr)
79 int fd = open(name, O_WRONLY);
83 ret = write(fd, valstr, strlen(valstr));
90 * Helper func to unexport gpio from sysfs
92 static void unexport_sysfs_gpio(int gpio)
96 if (!is_gpio_valid(gpio))
99 snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
100 if (open_write_close("/sys/class/gpio/unexport", gpiostr) < 0)
101 LOG_ERROR("Couldn't unexport gpio %d", gpio);
105 * Exports and sets up direction for gpio.
106 * If the gpio is an output, it is initialized according to init_high,
107 * otherwise it is ignored.
109 * If the gpio is already exported we just show a warning and continue; if
110 * openocd happened to crash (or was killed by user) then the gpios will not
111 * have been cleaned up.
113 static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
115 struct timeval timeout, now;
120 if (!is_gpio_valid(gpio))
123 snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
124 ret = open_write_close("/sys/class/gpio/export", gpiostr);
126 if (errno == EBUSY) {
127 LOG_WARNING("gpio %d is already exported", gpio);
129 LOG_ERROR("Couldn't export gpio %d", gpio);
130 LOG_ERROR("sysfsgpio: %s", strerror(errno));
135 gettimeofday(&timeout, NULL);
136 timeval_add_time(&timeout, 0, 500000);
138 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
140 ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
141 if (ret >= 0 || errno != EACCES)
143 gettimeofday(&now, NULL);
144 if (timeval_compare(&now, &timeout) >= 0)
149 LOG_ERROR("Couldn't set direction for gpio %d", gpio);
150 LOG_ERROR("sysfsgpio: %s", strerror(errno));
151 unexport_sysfs_gpio(gpio);
155 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
157 ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
158 if (ret >= 0 || errno != EACCES)
160 gettimeofday(&now, NULL);
161 if (timeval_compare(&now, &timeout) >= 0)
166 LOG_ERROR("Couldn't open value for gpio %d", gpio);
167 LOG_ERROR("sysfsgpio: %s", strerror(errno));
168 unexport_sysfs_gpio(gpio);
174 /* gpio numbers for each gpio. Negative values are invalid */
175 static int tck_gpio = -1;
176 static int tms_gpio = -1;
177 static int tdi_gpio = -1;
178 static int tdo_gpio = -1;
179 static int trst_gpio = -1;
180 static int srst_gpio = -1;
181 static int swclk_gpio = -1;
182 static int swdio_gpio = -1;
185 * file descriptors for /sys/class/gpio/gpioXX/value
186 * Set up during init.
188 static int tck_fd = -1;
189 static int tms_fd = -1;
190 static int tdi_fd = -1;
191 static int tdo_fd = -1;
192 static int trst_fd = -1;
193 static int srst_fd = -1;
194 static int swclk_fd = -1;
195 static int swdio_fd = -1;
197 static int last_swclk;
198 static int last_swdio;
199 static bool last_stored;
200 static bool swdio_input;
202 static void sysfsgpio_swdio_drive(bool is_output)
207 snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
208 ret = open_write_close(buf, is_output ? "high" : "in");
210 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
211 LOG_ERROR("sysfsgpio: %s", strerror(errno));
215 swdio_input = !is_output;
218 static int sysfsgpio_swdio_read(void)
222 /* important to seek to signal sysfs of new read */
223 lseek(swdio_fd, 0, SEEK_SET);
224 int ret = read(swdio_fd, &buf, sizeof(buf));
227 LOG_WARNING("reading swdio failed");
231 return buf[0] != '0';
234 static int sysfsgpio_swd_write(int swclk, int swdio)
236 const char one[] = "1";
237 const char zero[] = "0";
239 size_t bytes_written;
242 if (!last_stored || (swdio != last_swdio)) {
243 bytes_written = write(swdio_fd, swdio ? &one : &zero, 1);
244 if (bytes_written != 1)
245 LOG_WARNING("writing swdio failed");
249 /* write swclk last */
250 if (!last_stored || (swclk != last_swclk)) {
251 bytes_written = write(swclk_fd, swclk ? &one : &zero, 1);
252 if (bytes_written != 1)
253 LOG_WARNING("writing swclk failed");
264 * Bitbang interface read of TDO
266 * The sysfs value will read back either '0' or '1'. The trick here is to call
267 * lseek to bypass buffering in the sysfs kernel driver.
269 static bb_value_t sysfsgpio_read(void)
273 /* important to seek to signal sysfs of new read */
274 lseek(tdo_fd, 0, SEEK_SET);
275 int ret = read(tdo_fd, &buf, sizeof(buf));
278 LOG_WARNING("reading tdo failed");
282 return buf[0] == '0' ? BB_LOW : BB_HIGH;
286 * Bitbang interface write of TCK, TMS, TDI
288 * Seeing as this is the only function where the outputs are changed,
289 * we can cache the old value to avoid needlessly writing it.
291 static int sysfsgpio_write(int tck, int tms, int tdi)
293 const char one[] = "1";
294 const char zero[] = "0";
300 static int first_time;
301 size_t bytes_written;
310 if (tdi != last_tdi) {
311 bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
312 if (bytes_written != 1)
313 LOG_WARNING("writing tdi failed");
316 if (tms != last_tms) {
317 bytes_written = write(tms_fd, tms ? &one : &zero, 1);
318 if (bytes_written != 1)
319 LOG_WARNING("writing tms failed");
323 if (tck != last_tck) {
324 bytes_written = write(tck_fd, tck ? &one : &zero, 1);
325 if (bytes_written != 1)
326 LOG_WARNING("writing tck failed");
337 * Bitbang interface to manipulate reset lines SRST and TRST
339 * (1) assert or (0) deassert reset lines
341 static int sysfsgpio_reset(int trst, int srst)
343 LOG_DEBUG("sysfsgpio_reset");
344 const char one[] = "1";
345 const char zero[] = "0";
346 size_t bytes_written;
348 /* assume active low */
350 bytes_written = write(srst_fd, srst ? &zero : &one, 1);
351 if (bytes_written != 1)
352 LOG_WARNING("writing srst failed");
355 /* assume active low */
357 bytes_written = write(trst_fd, trst ? &zero : &one, 1);
358 if (bytes_written != 1)
359 LOG_WARNING("writing trst failed");
365 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
368 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
369 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
370 COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
371 COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
372 } else if (CMD_ARGC != 0) {
373 return ERROR_COMMAND_SYNTAX_ERROR;
377 "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
378 tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
383 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
386 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
388 command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
392 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
395 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
397 command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
401 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
404 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
406 command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
410 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
413 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
415 command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
419 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
422 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
424 command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
428 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
431 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
433 command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
437 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
440 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
441 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
442 } else if (CMD_ARGC != 0) {
443 return ERROR_COMMAND_SYNTAX_ERROR;
447 "SysfsGPIO nums: swclk = %d, swdio = %d",
448 swclk_gpio, swdio_gpio);
453 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
456 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
458 command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
462 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
465 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
467 command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
471 static const struct command_registration sysfsgpio_subcommand_handlers[] = {
474 .handler = &sysfsgpio_handle_jtag_gpionums,
475 .mode = COMMAND_CONFIG,
476 .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
477 .usage = "[tck tms tdi tdo]",
481 .handler = &sysfsgpio_handle_jtag_gpionum_tck,
482 .mode = COMMAND_CONFIG,
483 .help = "gpio number for tck.",
488 .handler = &sysfsgpio_handle_jtag_gpionum_tms,
489 .mode = COMMAND_CONFIG,
490 .help = "gpio number for tms.",
495 .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
496 .mode = COMMAND_CONFIG,
497 .help = "gpio number for tdo.",
502 .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
503 .mode = COMMAND_CONFIG,
504 .help = "gpio number for tdi.",
509 .handler = &sysfsgpio_handle_jtag_gpionum_srst,
510 .mode = COMMAND_CONFIG,
511 .help = "gpio number for srst.",
516 .handler = &sysfsgpio_handle_jtag_gpionum_trst,
517 .mode = COMMAND_CONFIG,
518 .help = "gpio number for trst.",
523 .handler = &sysfsgpio_handle_swd_gpionums,
524 .mode = COMMAND_CONFIG,
525 .help = "gpio numbers for swclk, swdio. (in that order)",
526 .usage = "[swclk swdio]",
530 .handler = &sysfsgpio_handle_swd_gpionum_swclk,
531 .mode = COMMAND_CONFIG,
532 .help = "gpio number for swclk.",
537 .handler = &sysfsgpio_handle_swd_gpionum_swdio,
538 .mode = COMMAND_CONFIG,
539 .help = "gpio number for swdio.",
542 COMMAND_REGISTRATION_DONE
545 static const struct command_registration sysfsgpio_command_handlers[] = {
549 .help = "perform sysfsgpio management",
550 .chain = sysfsgpio_subcommand_handlers,
553 COMMAND_REGISTRATION_DONE
556 static int sysfsgpio_init(void);
557 static int sysfsgpio_quit(void);
559 static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
561 static struct jtag_interface sysfsgpio_interface = {
562 .supported = DEBUG_CAP_TMS_SEQ,
563 .execute_queue = bitbang_execute_queue,
566 struct adapter_driver sysfsgpio_adapter_driver = {
568 .transports = sysfsgpio_transports,
569 .commands = sysfsgpio_command_handlers,
571 .init = sysfsgpio_init,
572 .quit = sysfsgpio_quit,
573 .reset = sysfsgpio_reset,
575 .jtag_ops = &sysfsgpio_interface,
576 .swd_ops = &bitbang_swd,
579 static struct bitbang_interface sysfsgpio_bitbang = {
580 .read = sysfsgpio_read,
581 .write = sysfsgpio_write,
582 .swdio_read = sysfsgpio_swdio_read,
583 .swdio_drive = sysfsgpio_swdio_drive,
584 .swd_write = sysfsgpio_swd_write,
588 /* helper func to close and cleanup files only if they were valid/ used */
589 static void cleanup_fd(int fd, int gpio)
595 unexport_sysfs_gpio(gpio);
599 static void cleanup_all_fds(void)
601 if (transport_is_jtag()) {
602 cleanup_fd(tck_fd, tck_gpio);
603 cleanup_fd(tms_fd, tms_gpio);
604 cleanup_fd(tdi_fd, tdi_gpio);
605 cleanup_fd(tdo_fd, tdo_gpio);
606 cleanup_fd(trst_fd, trst_gpio);
608 if (transport_is_swd()) {
609 cleanup_fd(swclk_fd, swclk_gpio);
610 cleanup_fd(swdio_fd, swdio_gpio);
612 cleanup_fd(srst_fd, srst_gpio);
615 static bool sysfsgpio_jtag_mode_possible(void)
617 if (!is_gpio_valid(tck_gpio))
619 if (!is_gpio_valid(tms_gpio))
621 if (!is_gpio_valid(tdi_gpio))
623 if (!is_gpio_valid(tdo_gpio))
628 static bool sysfsgpio_swd_mode_possible(void)
630 if (!is_gpio_valid(swclk_gpio))
632 if (!is_gpio_valid(swdio_gpio))
637 static int sysfsgpio_init(void)
639 bitbang_interface = &sysfsgpio_bitbang;
641 LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
644 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
645 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
646 * For SWD, SWCLK and SWDIO are configures as output high.
649 if (transport_is_jtag()) {
650 if (!sysfsgpio_jtag_mode_possible()) {
651 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode");
652 return ERROR_JTAG_INIT_FAILED;
655 tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
659 tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
663 tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
667 tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
671 /* assume active low*/
672 if (trst_gpio >= 0) {
673 trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
679 if (transport_is_swd()) {
680 if (!sysfsgpio_swd_mode_possible()) {
681 LOG_ERROR("Require swclk and swdio gpio for SWD mode");
682 return ERROR_JTAG_INIT_FAILED;
685 swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
689 swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
694 /* assume active low*/
695 if (srst_gpio >= 0) {
696 srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
705 return ERROR_JTAG_INIT_FAILED;
708 static int sysfsgpio_quit(void)