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 int 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 struct jtag_interface sysfsgpio_interface
= {
556 .supported
= DEBUG_CAP_TMS_SEQ
,
557 .execute_queue
= bitbang_execute_queue
,
558 .transports
= sysfsgpio_transports
,
560 .commands
= sysfsgpio_command_handlers
,
561 .init
= sysfsgpio_init
,
562 .quit
= sysfsgpio_quit
,
565 static struct bitbang_interface sysfsgpio_bitbang
= {
566 .read
= sysfsgpio_read
,
567 .write
= sysfsgpio_write
,
568 .reset
= sysfsgpio_reset
,
569 .swdio_read
= sysfsgpio_swdio_read
,
570 .swdio_drive
= sysfsgpio_swdio_drive
,
574 /* helper func to close and cleanup files only if they were valid/ used */
575 static void cleanup_fd(int fd
, int gpio
)
581 unexport_sysfs_gpio(gpio
);
585 static void cleanup_all_fds(void)
587 cleanup_fd(tck_fd
, tck_gpio
);
588 cleanup_fd(tms_fd
, tms_gpio
);
589 cleanup_fd(tdi_fd
, tdi_gpio
);
590 cleanup_fd(tdo_fd
, tdo_gpio
);
591 cleanup_fd(trst_fd
, trst_gpio
);
592 cleanup_fd(srst_fd
, srst_gpio
);
593 cleanup_fd(swclk_fd
, swclk_gpio
);
594 cleanup_fd(swdio_fd
, swdio_gpio
);
597 static bool sysfsgpio_jtag_mode_possible(void)
599 if (!is_gpio_valid(tck_gpio
))
601 if (!is_gpio_valid(tms_gpio
))
603 if (!is_gpio_valid(tdi_gpio
))
605 if (!is_gpio_valid(tdo_gpio
))
610 static bool sysfsgpio_swd_mode_possible(void)
612 if (!is_gpio_valid(swclk_gpio
))
614 if (!is_gpio_valid(swdio_gpio
))
619 static int sysfsgpio_init(void)
621 bitbang_interface
= &sysfsgpio_bitbang
;
623 LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
625 if (sysfsgpio_jtag_mode_possible()) {
626 if (sysfsgpio_swd_mode_possible())
627 LOG_INFO("JTAG and SWD modes enabled");
629 LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
630 } else if (sysfsgpio_swd_mode_possible()) {
631 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
633 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
634 return ERROR_JTAG_INIT_FAILED
;
639 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
640 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
641 * For SWD, SWCLK and SWDIO are configures as output high.
644 tck_fd
= setup_sysfs_gpio(tck_gpio
, 1, 0);
650 tms_fd
= setup_sysfs_gpio(tms_gpio
, 1, 1);
656 tdi_fd
= setup_sysfs_gpio(tdi_gpio
, 1, 0);
662 tdo_fd
= setup_sysfs_gpio(tdo_gpio
, 0, 0);
667 /* assume active low*/
668 if (trst_gpio
>= 0) {
669 trst_fd
= setup_sysfs_gpio(trst_gpio
, 1, 1);
674 /* assume active low*/
675 if (srst_gpio
>= 0) {
676 srst_fd
= setup_sysfs_gpio(srst_gpio
, 1, 1);
681 if (swclk_gpio
>= 0) {
682 swclk_fd
= setup_sysfs_gpio(swclk_gpio
, 1, 0);
687 if (swdio_gpio
>= 0) {
688 swdio_fd
= setup_sysfs_gpio(swdio_gpio
, 1, 0);
693 if (sysfsgpio_swd_mode_possible()) {
695 bitbang_swd_switch_seq(JTAG_TO_SWD
);
697 bitbang_swd_switch_seq(SWD_TO_JTAG
);
704 return ERROR_JTAG_INIT_FAILED
;
707 static int sysfsgpio_quit(void)
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