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 <jtag/interface.h>
59 * Helper func to determine if gpio number valid
61 * Assume here that there will be less than 1000 gpios on a system
63 static int is_gpio_valid(int gpio
)
65 return gpio
>= 0 && gpio
< 1000;
69 * Helper func to open, write to and close a file
70 * name and valstr must be null terminated.
72 * Returns negative on failure.
74 static int open_write_close(const char *name
, const char *valstr
)
77 int fd
= open(name
, O_WRONLY
);
81 ret
= write(fd
, valstr
, strlen(valstr
));
88 * Helper func to unexport gpio from sysfs
90 static void unexport_sysfs_gpio(int gpio
)
94 if (!is_gpio_valid(gpio
))
97 snprintf(gpiostr
, sizeof(gpiostr
), "%d", gpio
);
98 if (open_write_close("/sys/class/gpio/unexport", gpiostr
) < 0)
99 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
)
119 if (!is_gpio_valid(gpio
))
122 snprintf(gpiostr
, sizeof(gpiostr
), "%d", gpio
);
123 ret
= open_write_close("/sys/class/gpio/export", gpiostr
);
125 if (errno
== EBUSY
) {
126 LOG_WARNING("gpio %d is already exported", gpio
);
128 LOG_ERROR("Couldn't export gpio %d", gpio
);
129 perror("sysfsgpio: ");
134 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/direction", gpio
);
135 ret
= open_write_close(buf
, is_output
? (init_high
? "high" : "low") : "in");
137 LOG_ERROR("Couldn't set direction for gpio %d", gpio
);
138 perror("sysfsgpio: ");
139 unexport_sysfs_gpio(gpio
);
143 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/value", gpio
);
144 ret
= open(buf
, O_RDWR
| O_NONBLOCK
| O_SYNC
);
146 LOG_ERROR("Couldn't open value for gpio %d", gpio
);
147 perror("sysfsgpio: ");
148 unexport_sysfs_gpio(gpio
);
154 /* gpio numbers for each gpio. Negative values are invalid */
155 static int tck_gpio
= -1;
156 static int tms_gpio
= -1;
157 static int tdi_gpio
= -1;
158 static int tdo_gpio
= -1;
159 static int trst_gpio
= -1;
160 static int srst_gpio
= -1;
161 static int swclk_gpio
= -1;
162 static int swdio_gpio
= -1;
165 * file descriptors for /sys/class/gpio/gpioXX/value
166 * Set up during init.
168 static int tck_fd
= -1;
169 static int tms_fd
= -1;
170 static int tdi_fd
= -1;
171 static int tdo_fd
= -1;
172 static int trst_fd
= -1;
173 static int srst_fd
= -1;
174 static int swclk_fd
= -1;
175 static int swdio_fd
= -1;
177 static int last_swclk
;
178 static int last_swdio
;
179 static bool last_stored
;
180 static bool swdio_input
;
182 static void sysfsgpio_swdio_drive(bool is_output
)
187 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/direction", swdio_gpio
);
188 ret
= open_write_close(buf
, is_output
? "high" : "in");
190 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio
);
191 perror("sysfsgpio: ");
195 swdio_input
= !is_output
;
198 static int sysfsgpio_swdio_read(void)
202 /* important to seek to signal sysfs of new read */
203 lseek(swdio_fd
, 0, SEEK_SET
);
204 int ret
= read(swdio_fd
, &buf
, sizeof(buf
));
207 LOG_WARNING("reading swdio failed");
211 return buf
[0] != '0';
214 static void sysfsgpio_swdio_write(int swclk
, int swdio
)
216 const char one
[] = "1";
217 const char zero
[] = "0";
219 size_t bytes_written
;
222 if (!last_stored
|| (swdio
!= last_swdio
)) {
223 bytes_written
= write(swdio_fd
, swdio
? &one
: &zero
, 1);
224 if (bytes_written
!= 1)
225 LOG_WARNING("writing swdio failed");
229 /* write swclk last */
230 if (!last_stored
|| (swclk
!= last_swclk
)) {
231 bytes_written
= write(swclk_fd
, swclk
? &one
: &zero
, 1);
232 if (bytes_written
!= 1)
233 LOG_WARNING("writing swclk failed");
242 * Bitbang interface read of TDO
244 * The sysfs value will read back either '0' or '1'. The trick here is to call
245 * lseek to bypass buffering in the sysfs kernel driver.
247 static int sysfsgpio_read(void)
251 /* important to seek to signal sysfs of new read */
252 lseek(tdo_fd
, 0, SEEK_SET
);
253 int ret
= read(tdo_fd
, &buf
, sizeof(buf
));
256 LOG_WARNING("reading tdo failed");
260 return buf
[0] != '0';
264 * Bitbang interface write of TCK, TMS, TDI
266 * Seeing as this is the only function where the outputs are changed,
267 * we can cache the old value to avoid needlessly writing it.
269 static void sysfsgpio_write(int tck
, int tms
, int tdi
)
272 sysfsgpio_swdio_write(tck
, tdi
);
276 const char one
[] = "1";
277 const char zero
[] = "0";
283 static int first_time
;
284 size_t bytes_written
;
293 if (tdi
!= last_tdi
) {
294 bytes_written
= write(tdi_fd
, tdi
? &one
: &zero
, 1);
295 if (bytes_written
!= 1)
296 LOG_WARNING("writing tdi failed");
299 if (tms
!= last_tms
) {
300 bytes_written
= write(tms_fd
, tms
? &one
: &zero
, 1);
301 if (bytes_written
!= 1)
302 LOG_WARNING("writing tms failed");
306 if (tck
!= last_tck
) {
307 bytes_written
= write(tck_fd
, tck
? &one
: &zero
, 1);
308 if (bytes_written
!= 1)
309 LOG_WARNING("writing tck failed");
318 * Bitbang interface to manipulate reset lines SRST and TRST
320 * (1) assert or (0) deassert reset lines
322 static void sysfsgpio_reset(int trst
, int srst
)
324 LOG_DEBUG("sysfsgpio_reset");
325 const char one
[] = "1";
326 const char zero
[] = "0";
327 size_t bytes_written
;
329 /* assume active low */
331 bytes_written
= write(srst_fd
, srst
? &zero
: &one
, 1);
332 if (bytes_written
!= 1)
333 LOG_WARNING("writing srst failed");
336 /* assume active low */
338 bytes_written
= write(trst_fd
, trst
? &zero
: &one
, 1);
339 if (bytes_written
!= 1)
340 LOG_WARNING("writing trst failed");
344 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums
)
347 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
348 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[1], tms_gpio
);
349 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[2], tdi_gpio
);
350 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[3], tdo_gpio
);
351 } else if (CMD_ARGC
!= 0) {
352 return ERROR_COMMAND_SYNTAX_ERROR
;
355 command_print(CMD_CTX
,
356 "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
357 tck_gpio
, tms_gpio
, tdi_gpio
, tdo_gpio
);
362 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck
)
365 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
367 command_print(CMD_CTX
, "SysfsGPIO num: tck = %d", tck_gpio
);
371 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms
)
374 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tms_gpio
);
376 command_print(CMD_CTX
, "SysfsGPIO num: tms = %d", tms_gpio
);
380 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo
)
383 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdo_gpio
);
385 command_print(CMD_CTX
, "SysfsGPIO num: tdo = %d", tdo_gpio
);
389 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi
)
392 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdi_gpio
);
394 command_print(CMD_CTX
, "SysfsGPIO num: tdi = %d", tdi_gpio
);
398 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst
)
401 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], srst_gpio
);
403 command_print(CMD_CTX
, "SysfsGPIO num: srst = %d", srst_gpio
);
407 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst
)
410 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], trst_gpio
);
412 command_print(CMD_CTX
, "SysfsGPIO num: trst = %d", trst_gpio
);
416 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums
)
419 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swclk_gpio
);
420 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[1], swdio_gpio
);
421 } else if (CMD_ARGC
!= 0) {
422 return ERROR_COMMAND_SYNTAX_ERROR
;
425 command_print(CMD_CTX
,
426 "SysfsGPIO nums: swclk = %d, swdio = %d",
427 swclk_gpio
, swdio_gpio
);
432 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk
)
435 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swclk_gpio
);
437 command_print(CMD_CTX
, "SysfsGPIO num: swclk = %d", swclk_gpio
);
441 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio
)
444 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swdio_gpio
);
446 command_print(CMD_CTX
, "SysfsGPIO num: swdio = %d", swdio_gpio
);
450 static const struct command_registration sysfsgpio_command_handlers
[] = {
452 .name
= "sysfsgpio_jtag_nums",
453 .handler
= &sysfsgpio_handle_jtag_gpionums
,
454 .mode
= COMMAND_CONFIG
,
455 .help
= "gpio numbers for tck, tms, tdi, tdo. (in that order)",
456 .usage
= "(tck tms tdi tdo)* ",
459 .name
= "sysfsgpio_tck_num",
460 .handler
= &sysfsgpio_handle_jtag_gpionum_tck
,
461 .mode
= COMMAND_CONFIG
,
462 .help
= "gpio number for tck.",
465 .name
= "sysfsgpio_tms_num",
466 .handler
= &sysfsgpio_handle_jtag_gpionum_tms
,
467 .mode
= COMMAND_CONFIG
,
468 .help
= "gpio number for tms.",
471 .name
= "sysfsgpio_tdo_num",
472 .handler
= &sysfsgpio_handle_jtag_gpionum_tdo
,
473 .mode
= COMMAND_CONFIG
,
474 .help
= "gpio number for tdo.",
477 .name
= "sysfsgpio_tdi_num",
478 .handler
= &sysfsgpio_handle_jtag_gpionum_tdi
,
479 .mode
= COMMAND_CONFIG
,
480 .help
= "gpio number for tdi.",
483 .name
= "sysfsgpio_srst_num",
484 .handler
= &sysfsgpio_handle_jtag_gpionum_srst
,
485 .mode
= COMMAND_CONFIG
,
486 .help
= "gpio number for srst.",
489 .name
= "sysfsgpio_trst_num",
490 .handler
= &sysfsgpio_handle_jtag_gpionum_trst
,
491 .mode
= COMMAND_CONFIG
,
492 .help
= "gpio number for trst.",
495 .name
= "sysfsgpio_swd_nums",
496 .handler
= &sysfsgpio_handle_swd_gpionums
,
497 .mode
= COMMAND_CONFIG
,
498 .help
= "gpio numbers for swclk, swdio. (in that order)",
499 .usage
= "(swclk swdio)* ",
502 .name
= "sysfsgpio_swclk_num",
503 .handler
= &sysfsgpio_handle_swd_gpionum_swclk
,
504 .mode
= COMMAND_CONFIG
,
505 .help
= "gpio number for swclk.",
508 .name
= "sysfsgpio_swdio_num",
509 .handler
= &sysfsgpio_handle_swd_gpionum_swdio
,
510 .mode
= COMMAND_CONFIG
,
511 .help
= "gpio number for swdio.",
513 COMMAND_REGISTRATION_DONE
516 static int sysfsgpio_init(void);
517 static int sysfsgpio_quit(void);
519 static const char * const sysfsgpio_transports
[] = { "jtag", "swd", NULL
};
521 struct jtag_interface sysfsgpio_interface
= {
523 .supported
= DEBUG_CAP_TMS_SEQ
,
524 .execute_queue
= bitbang_execute_queue
,
525 .transports
= sysfsgpio_transports
,
527 .commands
= sysfsgpio_command_handlers
,
528 .init
= sysfsgpio_init
,
529 .quit
= sysfsgpio_quit
,
532 static struct bitbang_interface sysfsgpio_bitbang
= {
533 .read
= sysfsgpio_read
,
534 .write
= sysfsgpio_write
,
535 .reset
= sysfsgpio_reset
,
536 .swdio_read
= sysfsgpio_swdio_read
,
537 .swdio_drive
= sysfsgpio_swdio_drive
,
541 /* helper func to close and cleanup files only if they were valid/ used */
542 static void cleanup_fd(int fd
, int gpio
)
548 unexport_sysfs_gpio(gpio
);
552 static void cleanup_all_fds(void)
554 cleanup_fd(tck_fd
, tck_gpio
);
555 cleanup_fd(tms_fd
, tms_gpio
);
556 cleanup_fd(tdi_fd
, tdi_gpio
);
557 cleanup_fd(tdo_fd
, tdo_gpio
);
558 cleanup_fd(trst_fd
, trst_gpio
);
559 cleanup_fd(srst_fd
, srst_gpio
);
562 static bool sysfsgpio_jtag_mode_possible(void)
564 if (!is_gpio_valid(tck_gpio
))
566 if (!is_gpio_valid(tms_gpio
))
568 if (!is_gpio_valid(tdi_gpio
))
570 if (!is_gpio_valid(tdo_gpio
))
575 static bool sysfsgpio_swd_mode_possible(void)
577 if (!is_gpio_valid(swclk_gpio
))
579 if (!is_gpio_valid(swdio_gpio
))
584 static int sysfsgpio_init(void)
586 bitbang_interface
= &sysfsgpio_bitbang
;
588 LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
590 if (sysfsgpio_jtag_mode_possible()) {
591 if (sysfsgpio_swd_mode_possible())
592 LOG_INFO("JTAG and SWD modes enabled");
594 LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
595 if (!is_gpio_valid(trst_gpio
) && !is_gpio_valid(srst_gpio
)) {
596 LOG_ERROR("Require at least one of trst or srst gpios to be specified");
597 return ERROR_JTAG_INIT_FAILED
;
599 } else if (sysfsgpio_swd_mode_possible()) {
600 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
602 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
603 return ERROR_JTAG_INIT_FAILED
;
608 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
609 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
610 * For SWD, SWCLK and SWDIO are configures as output high.
613 tck_fd
= setup_sysfs_gpio(tck_gpio
, 1, 0);
619 tms_fd
= setup_sysfs_gpio(tms_gpio
, 1, 1);
625 tdi_fd
= setup_sysfs_gpio(tdi_gpio
, 1, 0);
631 tdo_fd
= setup_sysfs_gpio(tdo_gpio
, 0, 0);
636 /* assume active low*/
637 if (trst_gpio
>= 0) {
638 trst_fd
= setup_sysfs_gpio(trst_gpio
, 1, 1);
643 /* assume active low*/
644 if (srst_gpio
>= 0) {
645 srst_fd
= setup_sysfs_gpio(srst_gpio
, 1, 1);
650 if (swclk_gpio
>= 0) {
651 swclk_fd
= setup_sysfs_gpio(swclk_gpio
, 1, 0);
656 if (swdio_gpio
>= 0) {
657 swdio_fd
= setup_sysfs_gpio(swdio_gpio
, 1, 0);
662 if (sysfsgpio_swd_mode_possible()) {
664 bitbang_swd_switch_seq(JTAG_TO_SWD
);
666 bitbang_swd_switch_seq(SWD_TO_JTAG
);
673 return ERROR_JTAG_INIT_FAILED
;
676 static int sysfsgpio_quit(void)