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, write to the *
16 * Free Software Foundation, Inc., *
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
18 ***************************************************************************/
20 /* 2014-12: Addition of the SWD protocol support is based on the initial work
21 * on bcm2835gpio.c by Paul Fertser and modifications by Jean-Christian de Rivaz. */
25 * This driver implements a bitbang jtag interface using gpio lines via
27 * The aim of this driver implementation is use system GPIOs but avoid the
28 * need for a additional kernel driver.
29 * (Note memory mapped IO is another option, however it doesn't mix well with
30 * the kernel gpiolib driver - which makes sense I guess.)
32 * A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
33 * must be also be specified. The required jtag gpios are specified via the
34 * sysfsgpio_jtag_nums command or the relevant sysfsgpio_XXX_num commang.
35 * The srst and trst gpios are set via the sysfsgpio_srst_num and
36 * sysfsgpio_trst_num respectively. GPIO numbering follows the kernel
37 * convention of starting from 0.
39 * The gpios should not be in use by another entity, and must not be requested
40 * by a kernel driver without also being exported by it (otherwise they can't
41 * be exported by sysfs).
43 * The sysfs gpio interface can only manipulate one gpio at a time, so the
44 * bitbang write handler remembers the last state for tck, tms, tdi to avoid
46 * For speed the sysfs "value" entry is opened at init and held open.
47 * This results in considerable gains over open-write-close (45s vs 900s)
49 * Further work could address:
50 * -srst and trst open drain/ push pull
51 * -configurable active high/low for srst & trst
57 #include <jtag/interface.h>
61 * Helper func to determine if gpio number valid
63 * Assume here that there will be less than 1000 gpios on a system
65 static int is_gpio_valid(int gpio
)
67 return gpio
>= 0 && gpio
< 1000;
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
);
107 * Exports and sets up direction for gpio.
108 * If the gpio is an output, it is initialized according to init_high,
109 * otherwise it is ignored.
111 * If the gpio is already exported we just show a warning and continue; if
112 * openocd happened to crash (or was killed by user) then the gpios will not
113 * have been cleaned up.
115 static int setup_sysfs_gpio(int gpio
, int is_output
, int init_high
)
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 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/direction", gpio
);
137 ret
= open_write_close(buf
, is_output
? (init_high
? "high" : "low") : "in");
139 LOG_ERROR("Couldn't set direction for gpio %d", gpio
);
140 perror("sysfsgpio: ");
141 unexport_sysfs_gpio(gpio
);
145 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/value", gpio
);
146 ret
= open(buf
, O_RDWR
| O_NONBLOCK
| O_SYNC
);
148 LOG_ERROR("Couldn't open value for gpio %d", gpio
);
149 perror("sysfsgpio: ");
150 unexport_sysfs_gpio(gpio
);
156 /* gpio numbers for each gpio. Negative values are invalid */
157 static int tck_gpio
= -1;
158 static int tms_gpio
= -1;
159 static int tdi_gpio
= -1;
160 static int tdo_gpio
= -1;
161 static int trst_gpio
= -1;
162 static int srst_gpio
= -1;
163 static int swclk_gpio
= -1;
164 static int swdio_gpio
= -1;
167 * file descriptors for /sys/class/gpio/gpioXX/value
168 * Set up during init.
170 static int tck_fd
= -1;
171 static int tms_fd
= -1;
172 static int tdi_fd
= -1;
173 static int tdo_fd
= -1;
174 static int trst_fd
= -1;
175 static int srst_fd
= -1;
176 static int swclk_fd
= -1;
177 static int swdio_fd
= -1;
179 static int last_swclk
;
180 static int last_swdio
;
181 static bool last_stored
;
182 static bool swdio_input
;
184 static void sysfsgpio_swdio_drive(bool is_output
)
189 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/direction", swdio_gpio
);
190 ret
= open_write_close(buf
, is_output
? "high" : "in");
192 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio
);
193 perror("sysfsgpio: ");
197 swdio_input
= !is_output
;
200 static int sysfsgpio_swdio_read(void)
204 /* important to seek to signal sysfs of new read */
205 lseek(swdio_fd
, 0, SEEK_SET
);
206 int ret
= read(swdio_fd
, &buf
, sizeof(buf
));
209 LOG_WARNING("reading swdio failed");
213 return buf
[0] != '0';
216 static void sysfsgpio_swdio_write(int swclk
, int swdio
)
218 const char one
[] = "1";
219 const char zero
[] = "0";
221 size_t bytes_written
;
224 if (!last_stored
|| (swdio
!= last_swdio
)) {
225 bytes_written
= write(swdio_fd
, swdio
? &one
: &zero
, 1);
226 if (bytes_written
!= 1)
227 LOG_WARNING("writing swdio failed");
231 /* write swclk last */
232 if (!last_stored
|| (swclk
!= last_swclk
)) {
233 bytes_written
= write(swclk_fd
, swclk
? &one
: &zero
, 1);
234 if (bytes_written
!= 1)
235 LOG_WARNING("writing swclk failed");
244 * Bitbang interface read of TDO
246 * The sysfs value will read back either '0' or '1'. The trick here is to call
247 * lseek to bypass buffering in the sysfs kernel driver.
249 static int sysfsgpio_read(void)
253 /* important to seek to signal sysfs of new read */
254 lseek(tdo_fd
, 0, SEEK_SET
);
255 int ret
= read(tdo_fd
, &buf
, sizeof(buf
));
258 LOG_WARNING("reading tdo failed");
262 return buf
[0] != '0';
266 * Bitbang interface write of TCK, TMS, TDI
268 * Seeing as this is the only function where the outputs are changed,
269 * we can cache the old value to avoid needlessly writing it.
271 static void sysfsgpio_write(int tck
, int tms
, int tdi
)
274 sysfsgpio_swdio_write(tck
, tdi
);
278 const char one
[] = "1";
279 const char zero
[] = "0";
285 static int first_time
;
286 size_t bytes_written
;
295 if (tdi
!= last_tdi
) {
296 bytes_written
= write(tdi_fd
, tdi
? &one
: &zero
, 1);
297 if (bytes_written
!= 1)
298 LOG_WARNING("writing tdi failed");
301 if (tms
!= last_tms
) {
302 bytes_written
= write(tms_fd
, tms
? &one
: &zero
, 1);
303 if (bytes_written
!= 1)
304 LOG_WARNING("writing tms failed");
308 if (tck
!= last_tck
) {
309 bytes_written
= write(tck_fd
, tck
? &one
: &zero
, 1);
310 if (bytes_written
!= 1)
311 LOG_WARNING("writing tck failed");
320 * Bitbang interface to manipulate reset lines SRST and TRST
322 * (1) assert or (0) deassert reset lines
324 static void sysfsgpio_reset(int trst
, int srst
)
326 LOG_DEBUG("sysfsgpio_reset");
327 const char one
[] = "1";
328 const char zero
[] = "0";
329 size_t bytes_written
;
331 /* assume active low */
333 bytes_written
= write(srst_fd
, srst
? &zero
: &one
, 1);
334 if (bytes_written
!= 1)
335 LOG_WARNING("writing srst failed");
338 /* assume active low */
340 bytes_written
= write(trst_fd
, trst
? &zero
: &one
, 1);
341 if (bytes_written
!= 1)
342 LOG_WARNING("writing trst failed");
346 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums
)
349 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
350 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[1], tms_gpio
);
351 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[2], tdi_gpio
);
352 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[3], tdo_gpio
);
353 } else if (CMD_ARGC
!= 0) {
354 return ERROR_COMMAND_SYNTAX_ERROR
;
357 command_print(CMD_CTX
,
358 "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
359 tck_gpio
, tms_gpio
, tdi_gpio
, tdo_gpio
);
364 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck
)
367 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
369 command_print(CMD_CTX
, "SysfsGPIO num: tck = %d", tck_gpio
);
373 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms
)
376 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tms_gpio
);
378 command_print(CMD_CTX
, "SysfsGPIO num: tms = %d", tms_gpio
);
382 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo
)
385 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdo_gpio
);
387 command_print(CMD_CTX
, "SysfsGPIO num: tdo = %d", tdo_gpio
);
391 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi
)
394 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdi_gpio
);
396 command_print(CMD_CTX
, "SysfsGPIO num: tdi = %d", tdi_gpio
);
400 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst
)
403 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], srst_gpio
);
405 command_print(CMD_CTX
, "SysfsGPIO num: srst = %d", srst_gpio
);
409 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst
)
412 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], trst_gpio
);
414 command_print(CMD_CTX
, "SysfsGPIO num: trst = %d", trst_gpio
);
418 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums
)
421 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swclk_gpio
);
422 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[1], swdio_gpio
);
423 } else if (CMD_ARGC
!= 0) {
424 return ERROR_COMMAND_SYNTAX_ERROR
;
427 command_print(CMD_CTX
,
428 "SysfsGPIO nums: swclk = %d, swdio = %d",
429 swclk_gpio
, swdio_gpio
);
434 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk
)
437 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swclk_gpio
);
439 command_print(CMD_CTX
, "SysfsGPIO num: swclk = %d", swclk_gpio
);
443 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio
)
446 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], swdio_gpio
);
448 command_print(CMD_CTX
, "SysfsGPIO num: swdio = %d", swdio_gpio
);
452 static const struct command_registration sysfsgpio_command_handlers
[] = {
454 .name
= "sysfsgpio_jtag_nums",
455 .handler
= &sysfsgpio_handle_jtag_gpionums
,
456 .mode
= COMMAND_CONFIG
,
457 .help
= "gpio numbers for tck, tms, tdi, tdo. (in that order)",
458 .usage
= "(tck tms tdi tdo)* ",
461 .name
= "sysfsgpio_tck_num",
462 .handler
= &sysfsgpio_handle_jtag_gpionum_tck
,
463 .mode
= COMMAND_CONFIG
,
464 .help
= "gpio number for tck.",
467 .name
= "sysfsgpio_tms_num",
468 .handler
= &sysfsgpio_handle_jtag_gpionum_tms
,
469 .mode
= COMMAND_CONFIG
,
470 .help
= "gpio number for tms.",
473 .name
= "sysfsgpio_tdo_num",
474 .handler
= &sysfsgpio_handle_jtag_gpionum_tdo
,
475 .mode
= COMMAND_CONFIG
,
476 .help
= "gpio number for tdo.",
479 .name
= "sysfsgpio_tdi_num",
480 .handler
= &sysfsgpio_handle_jtag_gpionum_tdi
,
481 .mode
= COMMAND_CONFIG
,
482 .help
= "gpio number for tdi.",
485 .name
= "sysfsgpio_srst_num",
486 .handler
= &sysfsgpio_handle_jtag_gpionum_srst
,
487 .mode
= COMMAND_CONFIG
,
488 .help
= "gpio number for srst.",
491 .name
= "sysfsgpio_trst_num",
492 .handler
= &sysfsgpio_handle_jtag_gpionum_trst
,
493 .mode
= COMMAND_CONFIG
,
494 .help
= "gpio number for trst.",
497 .name
= "sysfsgpio_swd_nums",
498 .handler
= &sysfsgpio_handle_swd_gpionums
,
499 .mode
= COMMAND_CONFIG
,
500 .help
= "gpio numbers for swclk, swdio. (in that order)",
501 .usage
= "(swclk swdio)* ",
504 .name
= "sysfsgpio_swclk_num",
505 .handler
= &sysfsgpio_handle_swd_gpionum_swclk
,
506 .mode
= COMMAND_CONFIG
,
507 .help
= "gpio number for swclk.",
510 .name
= "sysfsgpio_swdio_num",
511 .handler
= &sysfsgpio_handle_swd_gpionum_swdio
,
512 .mode
= COMMAND_CONFIG
,
513 .help
= "gpio number for swdio.",
515 COMMAND_REGISTRATION_DONE
518 static int sysfsgpio_init(void);
519 static int sysfsgpio_quit(void);
521 static const char * const sysfsgpio_transports
[] = { "jtag", "swd", NULL
};
523 struct jtag_interface sysfsgpio_interface
= {
525 .supported
= DEBUG_CAP_TMS_SEQ
,
526 .execute_queue
= bitbang_execute_queue
,
527 .transports
= sysfsgpio_transports
,
529 .commands
= sysfsgpio_command_handlers
,
530 .init
= sysfsgpio_init
,
531 .quit
= sysfsgpio_quit
,
534 static struct bitbang_interface sysfsgpio_bitbang
= {
535 .read
= sysfsgpio_read
,
536 .write
= sysfsgpio_write
,
537 .reset
= sysfsgpio_reset
,
538 .swdio_read
= sysfsgpio_swdio_read
,
539 .swdio_drive
= sysfsgpio_swdio_drive
,
543 /* helper func to close and cleanup files only if they were valid/ used */
544 static void cleanup_fd(int fd
, int gpio
)
550 unexport_sysfs_gpio(gpio
);
554 static void cleanup_all_fds(void)
556 cleanup_fd(tck_fd
, tck_gpio
);
557 cleanup_fd(tms_fd
, tms_gpio
);
558 cleanup_fd(tdi_fd
, tdi_gpio
);
559 cleanup_fd(tdo_fd
, tdo_gpio
);
560 cleanup_fd(trst_fd
, trst_gpio
);
561 cleanup_fd(srst_fd
, srst_gpio
);
564 static bool sysfsgpio_jtag_mode_possible(void)
566 if (!is_gpio_valid(tck_gpio
))
568 if (!is_gpio_valid(tms_gpio
))
570 if (!is_gpio_valid(tdi_gpio
))
572 if (!is_gpio_valid(tdo_gpio
))
577 static bool sysfsgpio_swd_mode_possible(void)
579 if (!is_gpio_valid(swclk_gpio
))
581 if (!is_gpio_valid(swdio_gpio
))
586 static int sysfsgpio_init(void)
588 bitbang_interface
= &sysfsgpio_bitbang
;
590 LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
592 if (sysfsgpio_jtag_mode_possible()) {
593 if (sysfsgpio_swd_mode_possible())
594 LOG_INFO("JTAG and SWD modes enabled");
596 LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
597 if (!is_gpio_valid(trst_gpio
) && !is_gpio_valid(srst_gpio
)) {
598 LOG_ERROR("Require at least one of trst or srst gpios to be specified");
599 return ERROR_JTAG_INIT_FAILED
;
601 } else if (sysfsgpio_swd_mode_possible()) {
602 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
604 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
605 return ERROR_JTAG_INIT_FAILED
;
610 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
611 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
612 * For SWD, SWCLK and SWDIO are configures as output high.
615 tck_fd
= setup_sysfs_gpio(tck_gpio
, 1, 0);
621 tms_fd
= setup_sysfs_gpio(tms_gpio
, 1, 1);
627 tdi_fd
= setup_sysfs_gpio(tdi_gpio
, 1, 0);
633 tdo_fd
= setup_sysfs_gpio(tdo_gpio
, 0, 0);
638 /* assume active low*/
639 if (trst_gpio
>= 0) {
640 trst_fd
= setup_sysfs_gpio(trst_gpio
, 1, 1);
645 /* assume active low*/
646 if (srst_gpio
>= 0) {
647 srst_fd
= setup_sysfs_gpio(srst_gpio
, 1, 1);
652 if (swclk_gpio
>= 0) {
653 swclk_fd
= setup_sysfs_gpio(swclk_gpio
, 1, 0);
658 if (swdio_gpio
>= 0) {
659 swdio_fd
= setup_sysfs_gpio(swdio_gpio
, 1, 0);
664 if (sysfsgpio_swd_mode_possible()) {
666 bitbang_swd_switch_seq(JTAG_TO_SWD
);
668 bitbang_swd_switch_seq(SWD_TO_JTAG
);
675 return ERROR_JTAG_INIT_FAILED
;
678 static int sysfsgpio_quit(void)
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