src/jtag/drivers/sysfsgpio.c

   1 /***************************************************************************
   2  *   Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au *
   3  *                                                                         *
   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.                                   *
   8  *                                                                         *
   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.                          *
  13  *                                                                         *
  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  ***************************************************************************/
  17
  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. */
  20
  21 /**
  22  * @file
  23  * This driver implements a bitbang jtag interface using gpio lines via
  24  * sysfs.
  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.)
  29  *
  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.
  36  *
  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).
  40  *
  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
  43  * superfluous writes.
  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)
  46  *
  47  * Further work could address:
  48  *  -srst and trst open drain/ push pull
  49  *  -configurable active high/low for srst & trst
  50  */
  51 #ifdef HAVE_CONFIG_H
  52 #include "config.h"
  53 #endif
  54
  55 #include <helper/time_support.h>
  56 #include <jtag/interface.h>
  57 #include "bitbang.h"
  58
  59 /*
  60  * Helper func to determine if gpio number valid
  61  *
  62  * Assume here that there will be less than 10000 gpios on a system
  63  */
  64 static int is_gpio_valid(int gpio)
  65 {
  66         return gpio >= 0 && gpio < 10000;
  67 }
  68
  69 /*
  70  * Helper func to open, write to and close a file
  71  * name and valstr must be null terminated.
  72  *
  73  * Returns negative on failure.
  74  */
  75 static int open_write_close(const char *name, const char *valstr)
  76 {
  77         int ret;
  78         int fd = open(name, O_WRONLY);
  79         if (fd < 0)
  80                 return fd;
  81
  82         ret = write(fd, valstr, strlen(valstr));
  83         close(fd);
  84
  85         return ret;
  86 }
  87
  88 /*
  89  * Helper func to unexport gpio from sysfs
  90  */
  91 static void unexport_sysfs_gpio(int gpio)
  92 {
  93         char gpiostr[5];
  94
  95         if (!is_gpio_valid(gpio))
  96                 return;
  97
  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);
 101
 102         return;
 103 }
 104
 105 /*
 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.
 109  *
 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.
 113  */
 114 static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
 115 {
 116         struct timeval timeout, now;
 117         char buf[40];
 118         char gpiostr[5];
 119         int ret;
 120
 121         if (!is_gpio_valid(gpio))
 122                 return ERROR_OK;
 123
 124         snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
 125         ret = open_write_close("/sys/class/gpio/export", gpiostr);
 126         if (ret < 0) {
 127                 if (errno == EBUSY) {
 128                         LOG_WARNING("gpio %d is already exported", gpio);
 129                 } else {
 130                         LOG_ERROR("Couldn't export gpio %d", gpio);
 131                         perror("sysfsgpio: ");
 132                         return ERROR_FAIL;
 133                 }
 134         }
 135
 136         gettimeofday(&timeout, NULL);
 137         timeval_add_time(&timeout, 0, 500000);
 138
 139         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
 140         for (;;) {
 141                 ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
 142                 if (ret >= 0 || errno != EACCES)
 143                         break;
 144                 gettimeofday(&now, NULL);
 145                 if (timeval_compare(&now, &timeout) >= 0)
 146                         break;
 147                 jtag_sleep(10000);
 148         }
 149         if (ret < 0) {
 150                 LOG_ERROR("Couldn't set direction for gpio %d", gpio);
 151                 perror("sysfsgpio: ");
 152                 unexport_sysfs_gpio(gpio);
 153                 return ERROR_FAIL;
 154         }
 155
 156         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
 157         for (;;) {
 158                 ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
 159                 if (ret >= 0 || errno != EACCES)
 160                         break;
 161                 gettimeofday(&now, NULL);
 162                 if (timeval_compare(&now, &timeout) >= 0)
 163                         break;
 164                 jtag_sleep(10000);
 165         }
 166         if (ret < 0) {
 167                 LOG_ERROR("Couldn't open value for gpio %d", gpio);
 168                 perror("sysfsgpio: ");
 169                 unexport_sysfs_gpio(gpio);
 170         }
 171
 172         return ret;
 173 }
 174
 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;
 184
 185 /*
 186  * file descriptors for /sys/class/gpio/gpioXX/value
 187  * Set up during init.
 188  */
 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;
 197
 198 static int last_swclk;
 199 static int last_swdio;
 200 static bool last_stored;
 201 static bool swdio_input;
 202
 203 static void sysfsgpio_swdio_drive(bool is_output)
 204 {
 205         char buf[40];
 206         int ret;
 207
 208         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
 209         ret = open_write_close(buf, is_output ? "high" : "in");
 210         if (ret < 0) {
 211                 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
 212                 perror("sysfsgpio: ");
 213         }
 214
 215         last_stored = false;
 216         swdio_input = !is_output;
 217 }
 218
 219 static int sysfsgpio_swdio_read(void)
 220 {
 221         char buf[1];
 222
 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));
 226
 227         if (ret < 0) {
 228                 LOG_WARNING("reading swdio failed");
 229                 return 0;
 230         }
 231
 232         return buf[0] != '0';
 233 }
 234
 235 static void sysfsgpio_swdio_write(int swclk, int swdio)
 236 {
 237         const char one[] = "1";
 238         const char zero[] = "0";
 239
 240         size_t bytes_written;
 241
 242         if (!swdio_input) {
 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");
 247                 }
 248         }
 249
 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");
 255         }
 256
 257         last_swdio = swdio;
 258         last_swclk = swclk;
 259         last_stored = true;
 260 }
 261
 262 /*
 263  * Bitbang interface read of TDO
 264  *
 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.
 267  */
 268 static bb_value_t sysfsgpio_read(void)
 269 {
 270         char buf[1];
 271
 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));
 275
 276         if (ret < 0) {
 277                 LOG_WARNING("reading tdo failed");
 278                 return 0;
 279         }
 280
 281         return buf[0] == '0' ? BB_LOW : BB_HIGH;
 282 }
 283
 284 /*
 285  * Bitbang interface write of TCK, TMS, TDI
 286  *
 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.
 289  */
 290 static int sysfsgpio_write(int tck, int tms, int tdi)
 291 {
 292         if (swd_mode) {
 293                 sysfsgpio_swdio_write(tck, tdi);
 294                 return ERROR_OK;
 295         }
 296
 297         const char one[] = "1";
 298         const char zero[] = "0";
 299
 300         static int last_tck;
 301         static int last_tms;
 302         static int last_tdi;
 303
 304         static int first_time;
 305         size_t bytes_written;
 306
 307         if (!first_time) {
 308                 last_tck = !tck;
 309                 last_tms = !tms;
 310                 last_tdi = !tdi;
 311                 first_time = 1;
 312         }
 313
 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");
 318         }
 319
 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");
 324         }
 325
 326         /* write clk last */
 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");
 331         }
 332
 333         last_tdi = tdi;
 334         last_tms = tms;
 335         last_tck = tck;
 336
 337         return ERROR_OK;
 338 }
 339
 340 /*
 341  * Bitbang interface to manipulate reset lines SRST and TRST
 342  *
 343  * (1) assert or (0) deassert reset lines
 344  */
 345 static int sysfsgpio_reset(int trst, int srst)
 346 {
 347         LOG_DEBUG("sysfsgpio_reset");
 348         const char one[] = "1";
 349         const char zero[] = "0";
 350         size_t bytes_written;
 351
 352         /* assume active low */
 353         if (srst_fd >= 0) {
 354                 bytes_written = write(srst_fd, srst ? &zero : &one, 1);
 355                 if (bytes_written != 1)
 356                         LOG_WARNING("writing srst failed");
 357         }
 358
 359         /* assume active low */
 360         if (trst_fd >= 0) {
 361                 bytes_written = write(trst_fd, trst ? &zero : &one, 1);
 362                 if (bytes_written != 1)
 363                         LOG_WARNING("writing trst failed");
 364         }
 365
 366         return ERROR_OK;
 367 }
 368
 369 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
 370 {
 371         if (CMD_ARGC == 4) {
 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;
 378         }
 379
 380         command_print(CMD,
 381                         "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
 382                         tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
 383
 384         return ERROR_OK;
 385 }
 386
 387 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
 388 {
 389         if (CMD_ARGC == 1)
 390                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 391
 392         command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
 393         return ERROR_OK;
 394 }
 395
 396 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
 397 {
 398         if (CMD_ARGC == 1)
 399                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
 400
 401         command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
 402         return ERROR_OK;
 403 }
 404
 405 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
 406 {
 407         if (CMD_ARGC == 1)
 408                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
 409
 410         command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
 411         return ERROR_OK;
 412 }
 413
 414 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
 415 {
 416         if (CMD_ARGC == 1)
 417                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
 418
 419         command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
 420         return ERROR_OK;
 421 }
 422
 423 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
 424 {
 425         if (CMD_ARGC == 1)
 426                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
 427
 428         command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
 429         return ERROR_OK;
 430 }
 431
 432 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
 433 {
 434         if (CMD_ARGC == 1)
 435                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
 436
 437         command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
 438         return ERROR_OK;
 439 }
 440
 441 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
 442 {
 443         if (CMD_ARGC == 2) {
 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;
 448         }
 449
 450         command_print(CMD,
 451                         "SysfsGPIO nums: swclk = %d, swdio = %d",
 452                         swclk_gpio, swdio_gpio);
 453
 454         return ERROR_OK;
 455 }
 456
 457 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
 458 {
 459         if (CMD_ARGC == 1)
 460                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 461
 462         command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
 463         return ERROR_OK;
 464 }
 465
 466 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
 467 {
 468         if (CMD_ARGC == 1)
 469                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
 470
 471         command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
 472         return ERROR_OK;
 473 }
 474
 475 static const struct command_registration sysfsgpio_command_handlers[] = {
 476         {
 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]",
 482         },
 483         {
 484                 .name = "sysfsgpio_tck_num",
 485                 .handler = &sysfsgpio_handle_jtag_gpionum_tck,
 486                 .mode = COMMAND_CONFIG,
 487                 .help = "gpio number for tck.",
 488                 .usage = "[tck]",
 489         },
 490         {
 491                 .name = "sysfsgpio_tms_num",
 492                 .handler = &sysfsgpio_handle_jtag_gpionum_tms,
 493                 .mode = COMMAND_CONFIG,
 494                 .help = "gpio number for tms.",
 495                 .usage = "[tms]",
 496         },
 497         {
 498                 .name = "sysfsgpio_tdo_num",
 499                 .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
 500                 .mode = COMMAND_CONFIG,
 501                 .help = "gpio number for tdo.",
 502                 .usage = "[tdo]",
 503         },
 504         {
 505                 .name = "sysfsgpio_tdi_num",
 506                 .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
 507                 .mode = COMMAND_CONFIG,
 508                 .help = "gpio number for tdi.",
 509                 .usage = "[tdi]",
 510         },
 511         {
 512                 .name = "sysfsgpio_srst_num",
 513                 .handler = &sysfsgpio_handle_jtag_gpionum_srst,
 514                 .mode = COMMAND_CONFIG,
 515                 .help = "gpio number for srst.",
 516                 .usage = "[srst]",
 517         },
 518         {
 519                 .name = "sysfsgpio_trst_num",
 520                 .handler = &sysfsgpio_handle_jtag_gpionum_trst,
 521                 .mode = COMMAND_CONFIG,
 522                 .help = "gpio number for trst.",
 523                 .usage = "[trst]",
 524         },
 525         {
 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]",
 531         },
 532         {
 533                 .name = "sysfsgpio_swclk_num",
 534                 .handler = &sysfsgpio_handle_swd_gpionum_swclk,
 535                 .mode = COMMAND_CONFIG,
 536                 .help = "gpio number for swclk.",
 537                 .usage = "[swclk]",
 538         },
 539         {
 540                 .name = "sysfsgpio_swdio_num",
 541                 .handler = &sysfsgpio_handle_swd_gpionum_swdio,
 542                 .mode = COMMAND_CONFIG,
 543                 .help = "gpio number for swdio.",
 544                 .usage = "[swdio]",
 545         },
 546         COMMAND_REGISTRATION_DONE
 547 };
 548
 549 static int sysfsgpio_init(void);
 550 static int sysfsgpio_quit(void);
 551
 552 static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
 553
 554 static struct jtag_interface sysfsgpio_interface = {
 555         .supported = DEBUG_CAP_TMS_SEQ,
 556         .execute_queue = bitbang_execute_queue,
 557 };
 558
 559 struct adapter_driver sysfsgpio_adapter_driver = {
 560         .name = "sysfsgpio",
 561         .transports = sysfsgpio_transports,
 562         .commands = sysfsgpio_command_handlers,
 563
 564         .init = sysfsgpio_init,
 565         .quit = sysfsgpio_quit,
 566         .reset = sysfsgpio_reset,
 567
 568         .jtag_ops = &sysfsgpio_interface,
 569         .swd_ops = &bitbang_swd,
 570 };
 571
 572 static struct bitbang_interface sysfsgpio_bitbang = {
 573         .read = sysfsgpio_read,
 574         .write = sysfsgpio_write,
 575         .swdio_read = sysfsgpio_swdio_read,
 576         .swdio_drive = sysfsgpio_swdio_drive,
 577         .blink = 0
 578 };
 579
 580 /* helper func to close and cleanup files only if they were valid/ used */
 581 static void cleanup_fd(int fd, int gpio)
 582 {
 583         if (gpio >= 0) {
 584                 if (fd >= 0)
 585                         close(fd);
 586
 587                 unexport_sysfs_gpio(gpio);
 588         }
 589 }
 590
 591 static void cleanup_all_fds(void)
 592 {
 593         cleanup_fd(tck_fd, tck_gpio);
 594         cleanup_fd(tms_fd, tms_gpio);
 595         cleanup_fd(tdi_fd, tdi_gpio);
 596         cleanup_fd(tdo_fd, tdo_gpio);
 597         cleanup_fd(trst_fd, trst_gpio);
 598         cleanup_fd(srst_fd, srst_gpio);
 599         cleanup_fd(swclk_fd, swclk_gpio);
 600         cleanup_fd(swdio_fd, swdio_gpio);
 601 }
 602
 603 static bool sysfsgpio_jtag_mode_possible(void)
 604 {
 605         if (!is_gpio_valid(tck_gpio))
 606                 return 0;
 607         if (!is_gpio_valid(tms_gpio))
 608                 return 0;
 609         if (!is_gpio_valid(tdi_gpio))
 610                 return 0;
 611         if (!is_gpio_valid(tdo_gpio))
 612                 return 0;
 613         return 1;
 614 }
 615
 616 static bool sysfsgpio_swd_mode_possible(void)
 617 {
 618         if (!is_gpio_valid(swclk_gpio))
 619                 return 0;
 620         if (!is_gpio_valid(swdio_gpio))
 621                 return 0;
 622         return 1;
 623 }
 624
 625 static int sysfsgpio_init(void)
 626 {
 627         bitbang_interface = &sysfsgpio_bitbang;
 628
 629         LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
 630
 631         if (sysfsgpio_jtag_mode_possible()) {
 632                 if (sysfsgpio_swd_mode_possible())
 633                         LOG_INFO("JTAG and SWD modes enabled");
 634                 else
 635                         LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
 636         } else if (sysfsgpio_swd_mode_possible()) {
 637                 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
 638         } else {
 639                 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
 640                 return ERROR_JTAG_INIT_FAILED;
 641         }
 642
 643
 644         /*
 645          * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
 646          * as outputs.  Drive TDI and TCK low, and TMS/TRST/SRST high.
 647          * For SWD, SWCLK and SWDIO are configures as output high.
 648          */
 649         if (tck_gpio >= 0) {
 650                 tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
 651                 if (tck_fd < 0)
 652                         goto out_error;
 653         }
 654
 655         if (tms_gpio >= 0) {
 656                 tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
 657                 if (tms_fd < 0)
 658                         goto out_error;
 659         }
 660
 661         if (tdi_gpio >= 0) {
 662                 tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
 663                 if (tdi_fd < 0)
 664                         goto out_error;
 665         }
 666
 667         if (tdo_gpio >= 0) {
 668                 tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
 669                 if (tdo_fd < 0)
 670                         goto out_error;
 671         }
 672
 673         /* assume active low*/
 674         if (trst_gpio >= 0) {
 675                 trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
 676                 if (trst_fd < 0)
 677                         goto out_error;
 678         }
 679
 680         /* assume active low*/
 681         if (srst_gpio >= 0) {
 682                 srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
 683                 if (srst_fd < 0)
 684                         goto out_error;
 685         }
 686
 687         if (swclk_gpio >= 0) {
 688                 swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
 689                 if (swclk_fd < 0)
 690                         goto out_error;
 691         }
 692
 693         if (swdio_gpio >= 0) {
 694                 swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
 695                 if (swdio_fd < 0)
 696                         goto out_error;
 697         }
 698
 699         if (sysfsgpio_swd_mode_possible()) {
 700                 if (swd_mode)
 701                         bitbang_swd_switch_seq(JTAG_TO_SWD);
 702                 else
 703                         bitbang_swd_switch_seq(SWD_TO_JTAG);
 704         }
 705
 706         return ERROR_OK;
 707
 708 out_error:
 709         cleanup_all_fds();
 710         return ERROR_JTAG_INIT_FAILED;
 711 }
 712
 713 static int sysfsgpio_quit(void)
 714 {
 715         cleanup_all_fds();
 716         return ERROR_OK;
 717 }
 718