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 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
18 ***************************************************************************/
21 * This driver implements a bitbang jtag interface using gpio lines via
23 * The aim of this driver implementation is use system GPIOs but avoid the
24 * need for a additional kernel driver.
25 * (Note memory mapped IO is another option, however it doesn't mix well with
26 * the kernel gpiolib driver - which makes sense I guess.)
28 * A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
29 * must be also be specified. The required jtag gpios are specified via the
30 * sysfsgpio_jtag_nums command or the relevant sysfsgpio_XXX_num commang.
31 * The srst and trst gpios are set via the sysfsgpio_srst_num and
32 * sysfsgpio_trst_num respectively. GPIO numbering follows the kernel
33 * convention of starting from 0.
35 * The gpios should not be in use by another entity, and must not be requested
36 * by a kernel driver without also being exported by it (otherwise they can't
37 * be exported by sysfs).
39 * The sysfs gpio interface can only manipulate one gpio at a time, so the
40 * bitbang write handler remembers the last state for tck, tms, tdi to avoid
42 * For speed the sysfs "value" entry is opened at init and held open.
43 * This results in considerable gains over open-write-close (45s vs 900s)
45 * Further work could address:
46 * -srst and trst open drain/ push pull
47 * -configurable active high/low for srst & trst
53 #include <jtag/interface.h>
57 * Helper func to determine if gpio number valid
59 * Assume here that there will be less than 1000 gpios on a system
61 static int is_gpio_valid(int gpio
)
63 return gpio
>= 0 && gpio
< 1000;
67 * Helper func to open, write to and close a file
68 * name and valstr must be null terminated.
70 * Returns negative on failure.
72 static int open_write_close(const char *name
, const char *valstr
)
75 int fd
= open(name
, O_WRONLY
);
79 ret
= write(fd
, valstr
, strlen(valstr
));
86 * Helper func to unexport gpio from sysfs
88 static void unexport_sysfs_gpio(int gpio
)
92 if (!is_gpio_valid(gpio
))
95 snprintf(gpiostr
, sizeof(gpiostr
), "%d", gpio
);
96 if (open_write_close("/sys/class/gpio/unexport", gpiostr
) < 0)
97 LOG_ERROR("Couldn't unexport gpio %d", gpio
);
103 * Exports and sets up direction for gpio.
104 * If the gpio is an output, it is initialized according to init_high,
105 * otherwise it is ignored.
107 * If the gpio is already exported we just show a warning and continue; if
108 * openocd happened to crash (or was killed by user) then the gpios will not
109 * have been cleaned up.
111 static int setup_sysfs_gpio(int gpio
, int is_output
, int init_high
)
117 if (!is_gpio_valid(gpio
))
120 snprintf(gpiostr
, sizeof(gpiostr
), "%d", gpio
);
121 ret
= open_write_close("/sys/class/gpio/export", gpiostr
);
123 if (errno
== EBUSY
) {
124 LOG_WARNING("gpio %d is already exported", gpio
);
126 LOG_ERROR("Couldn't export gpio %d", gpio
);
127 perror("sysfsgpio: ");
132 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/direction", gpio
);
133 ret
= open_write_close(buf
, is_output
? (init_high
? "high" : "low") : "in");
135 LOG_ERROR("Couldn't set direction for gpio %d", gpio
);
136 perror("sysfsgpio: ");
137 unexport_sysfs_gpio(gpio
);
141 snprintf(buf
, sizeof(buf
), "/sys/class/gpio/gpio%d/value", gpio
);
143 ret
= open(buf
, O_WRONLY
| O_NONBLOCK
| O_SYNC
);
145 ret
= open(buf
, O_RDONLY
| O_NONBLOCK
| O_SYNC
);
148 unexport_sysfs_gpio(gpio
);
154 * file descriptors for /sys/class/gpio/gpioXX/value
155 * Set up during init.
157 static int tck_fd
= -1;
158 static int tms_fd
= -1;
159 static int tdi_fd
= -1;
160 static int tdo_fd
= -1;
161 static int trst_fd
= -1;
162 static int srst_fd
= -1;
165 * Bitbang interface read of TDO
167 * The sysfs value will read back either '0' or '1'. The trick here is to call
168 * lseek to bypass buffering in the sysfs kernel driver.
170 static int sysfsgpio_read(void)
174 /* important to seek to signal sysfs of new read */
175 lseek(tdo_fd
, 0, SEEK_SET
);
176 int ret
= read(tdo_fd
, &buf
, sizeof(buf
));
179 LOG_WARNING("reading tdo failed");
183 return buf
[0] == '1';
187 * Bitbang interface write of TCK, TMS, TDI
189 * Seeing as this is the only function where the outputs are changed,
190 * we can cache the old value to avoid needlessly writing it.
192 static void sysfsgpio_write(int tck
, int tms
, int tdi
)
194 const char one
[] = "1";
195 const char zero
[] = "0";
201 static int first_time
;
211 write(tdi_fd
, tdi
? &one
: &zero
, 1);
213 write(tms_fd
, tms
? &one
: &zero
, 1);
216 write(tck_fd
, tck
? &one
: &zero
, 1);
224 * Bitbang interface to manipulate reset lines SRST and TRST
226 * (1) assert or (0) deassert reset lines
228 static void sysfsgpio_reset(int trst
, int srst
)
230 const char one
[] = "1";
231 const char zero
[] = "0";
233 /* assume active low */
235 write(srst_fd
, srst
? &zero
: &one
, 1);
237 /* assume active low */
239 write(trst_fd
, trst
? &zero
: &one
, 1);
242 /* No speed control is implemented yet */
243 static int sysfsgpio_speed(int speed
)
248 static int sysfsgpio_khz(int khz
, int *jtag_speed
)
250 /* no adaptive clocking */
258 static int sysfsgpio_speed_div(int speed
, int *khz
)
264 /* gpio numbers for each gpio. Negative values are invalid */
265 static int tck_gpio
= -1;
266 static int tms_gpio
= -1;
267 static int tdi_gpio
= -1;
268 static int tdo_gpio
= -1;
269 static int trst_gpio
= -1;
270 static int srst_gpio
= -1;
272 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums
)
275 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
276 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[1], tms_gpio
);
277 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[2], tdi_gpio
);
278 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[3], tdo_gpio
);
279 } else if (CMD_ARGC
!= 0) {
280 return ERROR_COMMAND_SYNTAX_ERROR
;
283 command_print(CMD_CTX
,
284 "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdi = %d",
285 tck_gpio
, tms_gpio
, tdi_gpio
, tdo_gpio
);
290 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck
)
293 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tck_gpio
);
295 command_print(CMD_CTX
, "SysfsGPIO num: tck = %d", tck_gpio
);
299 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms
)
302 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tms_gpio
);
304 command_print(CMD_CTX
, "SysfsGPIO num: tms = %d", tms_gpio
);
308 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo
)
311 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdo_gpio
);
313 command_print(CMD_CTX
, "SysfsGPIO num: tdo = %d", tdo_gpio
);
317 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi
)
320 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], tdi_gpio
);
322 command_print(CMD_CTX
, "SysfsGPIO num: tdi = %d", tdi_gpio
);
326 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst
)
329 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], srst_gpio
);
331 command_print(CMD_CTX
, "SysfsGPIO num: srst = %d", srst_gpio
);
335 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst
)
338 COMMAND_PARSE_NUMBER(int, CMD_ARGV
[0], trst_gpio
);
340 command_print(CMD_CTX
, "SysfsGPIO num: trst = %d", trst_gpio
);
344 static const struct command_registration sysfsgpio_command_handlers
[] = {
346 .name
= "sysfsgpio_jtag_nums",
347 .handler
= &sysfsgpio_handle_jtag_gpionums
,
348 .mode
= COMMAND_CONFIG
,
349 .help
= "gpio numbers for tck, tms, tdi, tdo. (in that order)",
350 .usage
= "(tck tms tdi tdo)* ",
353 .name
= "sysfsgpio_tck_num",
354 .handler
= &sysfsgpio_handle_jtag_gpionum_tck
,
355 .mode
= COMMAND_CONFIG
,
356 .help
= "gpio number for tck.",
359 .name
= "sysfsgpio_tms_num",
360 .handler
= &sysfsgpio_handle_jtag_gpionum_tms
,
361 .mode
= COMMAND_CONFIG
,
362 .help
= "gpio number for tms.",
365 .name
= "sysfsgpio_tdo_num",
366 .handler
= &sysfsgpio_handle_jtag_gpionum_tdo
,
367 .mode
= COMMAND_CONFIG
,
368 .help
= "gpio number for tdo.",
371 .name
= "sysfsgpio_tdi_num",
372 .handler
= &sysfsgpio_handle_jtag_gpionum_tdi
,
373 .mode
= COMMAND_CONFIG
,
374 .help
= "gpio number for tdi.",
377 .name
= "sysfsgpio_srst_num",
378 .handler
= &sysfsgpio_handle_jtag_gpionum_srst
,
379 .mode
= COMMAND_CONFIG
,
380 .help
= "gpio number for srst.",
383 .name
= "sysfsgpio_trst_num",
384 .handler
= &sysfsgpio_handle_jtag_gpionum_trst
,
385 .mode
= COMMAND_CONFIG
,
386 .help
= "gpio number for trst.",
388 COMMAND_REGISTRATION_DONE
391 static int sysfsgpio_init(void);
392 static int sysfsgpio_quit(void);
394 struct jtag_interface sysfsgpio_interface
= {
396 .supported
= DEBUG_CAP_TMS_SEQ
,
397 .execute_queue
= bitbang_execute_queue
,
398 .transports
= jtag_only
,
399 .speed
= sysfsgpio_speed
,
400 .khz
= sysfsgpio_khz
,
401 .speed_div
= sysfsgpio_speed_div
,
402 .commands
= sysfsgpio_command_handlers
,
403 .init
= sysfsgpio_init
,
404 .quit
= sysfsgpio_quit
,
407 static struct bitbang_interface sysfsgpio_bitbang
= {
408 .read
= sysfsgpio_read
,
409 .write
= sysfsgpio_write
,
410 .reset
= sysfsgpio_reset
,
414 /* helper func to close and cleanup files only if they were valid/ used */
415 static void cleanup_fd(int fd
, int gpio
)
421 unexport_sysfs_gpio(gpio
);
425 static void cleanup_all_fds(void)
427 cleanup_fd(tck_fd
, tck_gpio
);
428 cleanup_fd(tms_fd
, tms_gpio
);
429 cleanup_fd(tdi_fd
, tdi_gpio
);
430 cleanup_fd(tdo_fd
, tdo_gpio
);
431 cleanup_fd(trst_fd
, trst_gpio
);
432 cleanup_fd(srst_fd
, srst_gpio
);
435 static int sysfsgpio_init(void)
437 bitbang_interface
= &sysfsgpio_bitbang
;
439 LOG_INFO("SysfsGPIO JTAG bitbang driver");
441 if (!(is_gpio_valid(tck_gpio
)
442 && is_gpio_valid(tms_gpio
)
443 && is_gpio_valid(tdi_gpio
)
444 && is_gpio_valid(tdo_gpio
))) {
445 if (!is_gpio_valid(tck_gpio
))
446 LOG_ERROR("gpio num for tck is invalid");
447 if (!is_gpio_valid(tms_gpio
))
448 LOG_ERROR("gpio num for tms is invalid");
449 if (!is_gpio_valid(tdo_gpio
))
450 LOG_ERROR("gpio num for tdo is invalid");
451 if (!is_gpio_valid(tdi_gpio
))
452 LOG_ERROR("gpio num for tdi is invalid");
454 LOG_ERROR("Require tck, tms, tdi and tdo gpios to all be specified");
455 return ERROR_JTAG_INIT_FAILED
;
458 if (!is_gpio_valid(trst_gpio
) && !is_gpio_valid(srst_gpio
)) {
459 LOG_ERROR("Require at least one of trst or srst gpios to be specified");
460 return ERROR_JTAG_INIT_FAILED
;
464 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
465 * as outputs. Drive TDI and TCK low, and TMS/TRST/SRST high.
467 tck_fd
= setup_sysfs_gpio(tck_gpio
, 1, 0);
471 tms_fd
= setup_sysfs_gpio(tms_gpio
, 1, 1);
475 tdi_fd
= setup_sysfs_gpio(tdi_gpio
, 1, 0);
479 tdo_fd
= setup_sysfs_gpio(tdo_gpio
, 0, 0);
483 /* assume active low*/
484 trst_fd
= setup_sysfs_gpio(trst_gpio
, 1, 1);
485 if (trst_gpio
> 0 && trst_fd
< 0)
488 /* assume active low*/
489 srst_fd
= setup_sysfs_gpio(srst_gpio
, 1, 1);
490 if (srst_gpio
> 0 && srst_fd
< 0)
497 return ERROR_JTAG_INIT_FAILED
;
500 static int sysfsgpio_quit(void)
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