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 commands.
  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 <transport/transport.h>
  58 #include "bitbang.h"
  59
  60 /*
  61  * Helper func to determine if gpio number valid
  62  *
  63  * Assume here that there will be less than 10000 gpios on a system
  64  */
  65 static bool is_gpio_valid(int gpio)
  66 {
  67         return gpio >= 0 && gpio < 10000;
  68 }
  69
  70 /*
  71  * Helper func to open, write to and close a file
  72  * name and valstr must be null terminated.
  73  *
  74  * Returns negative on failure.
  75  */
  76 static int open_write_close(const char *name, const char *valstr)
  77 {
  78         int ret;
  79         int fd = open(name, O_WRONLY);
  80         if (fd < 0)
  81                 return fd;
  82
  83         ret = write(fd, valstr, strlen(valstr));
  84         close(fd);
  85
  86         return ret;
  87 }
  88
  89 /*
  90  * Helper func to unexport gpio from sysfs
  91  */
  92 static void unexport_sysfs_gpio(int gpio)
  93 {
  94         char gpiostr[5];
  95
  96         if (!is_gpio_valid(gpio))
  97                 return;
  98
  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);
 102 }
 103
 104 /*
 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.
 108  *
 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.
 112  */
 113 static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
 114 {
 115         struct timeval timeout, now;
 116         char buf[40];
 117         char gpiostr[5];
 118         int ret;
 119
 120         if (!is_gpio_valid(gpio))
 121                 return ERROR_OK;
 122
 123         snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
 124         ret = open_write_close("/sys/class/gpio/export", gpiostr);
 125         if (ret < 0) {
 126                 if (errno == EBUSY) {
 127                         LOG_WARNING("gpio %d is already exported", gpio);
 128                 } else {
 129                         LOG_ERROR("Couldn't export gpio %d", gpio);
 130                         LOG_ERROR("sysfsgpio: %s", strerror(errno));
 131                         return ERROR_FAIL;
 132                 }
 133         }
 134
 135         gettimeofday(&timeout, NULL);
 136         timeval_add_time(&timeout, 0, 500000);
 137
 138         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
 139         for (;;) {
 140                 ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
 141                 if (ret >= 0 || errno != EACCES)
 142                         break;
 143                 gettimeofday(&now, NULL);
 144                 if (timeval_compare(&now, &timeout) >= 0)
 145                         break;
 146                 jtag_sleep(10000);
 147         }
 148         if (ret < 0) {
 149                 LOG_ERROR("Couldn't set direction for gpio %d", gpio);
 150                 LOG_ERROR("sysfsgpio: %s", strerror(errno));
 151                 unexport_sysfs_gpio(gpio);
 152                 return ERROR_FAIL;
 153         }
 154
 155         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
 156         for (;;) {
 157                 ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
 158                 if (ret >= 0 || errno != EACCES)
 159                         break;
 160                 gettimeofday(&now, NULL);
 161                 if (timeval_compare(&now, &timeout) >= 0)
 162                         break;
 163                 jtag_sleep(10000);
 164         }
 165         if (ret < 0) {
 166                 LOG_ERROR("Couldn't open value for gpio %d", gpio);
 167                 LOG_ERROR("sysfsgpio: %s", strerror(errno));
 168                 unexport_sysfs_gpio(gpio);
 169         }
 170
 171         return ret;
 172 }
 173
 174 /* gpio numbers for each gpio. Negative values are invalid */
 175 static int tck_gpio = -1;
 176 static int tms_gpio = -1;
 177 static int tdi_gpio = -1;
 178 static int tdo_gpio = -1;
 179 static int trst_gpio = -1;
 180 static int srst_gpio = -1;
 181 static int swclk_gpio = -1;
 182 static int swdio_gpio = -1;
 183
 184 /*
 185  * file descriptors for /sys/class/gpio/gpioXX/value
 186  * Set up during init.
 187  */
 188 static int tck_fd = -1;
 189 static int tms_fd = -1;
 190 static int tdi_fd = -1;
 191 static int tdo_fd = -1;
 192 static int trst_fd = -1;
 193 static int srst_fd = -1;
 194 static int swclk_fd = -1;
 195 static int swdio_fd = -1;
 196
 197 static int last_swclk;
 198 static int last_swdio;
 199 static bool last_stored;
 200 static bool swdio_input;
 201
 202 static void sysfsgpio_swdio_drive(bool is_output)
 203 {
 204         char buf[40];
 205         int ret;
 206
 207         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
 208         ret = open_write_close(buf, is_output ? "high" : "in");
 209         if (ret < 0) {
 210                 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
 211                 LOG_ERROR("sysfsgpio: %s", strerror(errno));
 212         }
 213
 214         last_stored = false;
 215         swdio_input = !is_output;
 216 }
 217
 218 static int sysfsgpio_swdio_read(void)
 219 {
 220         char buf[1];
 221
 222         /* important to seek to signal sysfs of new read */
 223         lseek(swdio_fd, 0, SEEK_SET);
 224         int ret = read(swdio_fd, &buf, sizeof(buf));
 225
 226         if (ret < 0) {
 227                 LOG_WARNING("reading swdio failed");
 228                 return 0;
 229         }
 230
 231         return buf[0] != '0';
 232 }
 233
 234 static int sysfsgpio_swd_write(int swclk, int swdio)
 235 {
 236         const char one[] = "1";
 237         const char zero[] = "0";
 238
 239         size_t bytes_written;
 240
 241         if (!swdio_input) {
 242                 if (!last_stored || (swdio != last_swdio)) {
 243                         bytes_written = write(swdio_fd, swdio ? &one : &zero, 1);
 244                         if (bytes_written != 1)
 245                                 LOG_WARNING("writing swdio failed");
 246                 }
 247         }
 248
 249         /* write swclk last */
 250         if (!last_stored || (swclk != last_swclk)) {
 251                 bytes_written = write(swclk_fd, swclk ? &one : &zero, 1);
 252                 if (bytes_written != 1)
 253                         LOG_WARNING("writing swclk failed");
 254         }
 255
 256         last_swdio = swdio;
 257         last_swclk = swclk;
 258         last_stored = true;
 259
 260         return ERROR_OK;
 261 }
 262
 263 /*
 264  * Bitbang interface read of TDO
 265  *
 266  * The sysfs value will read back either '0' or '1'. The trick here is to call
 267  * lseek to bypass buffering in the sysfs kernel driver.
 268  */
 269 static bb_value_t sysfsgpio_read(void)
 270 {
 271         char buf[1];
 272
 273         /* important to seek to signal sysfs of new read */
 274         lseek(tdo_fd, 0, SEEK_SET);
 275         int ret = read(tdo_fd, &buf, sizeof(buf));
 276
 277         if (ret < 0) {
 278                 LOG_WARNING("reading tdo failed");
 279                 return 0;
 280         }
 281
 282         return buf[0] == '0' ? BB_LOW : BB_HIGH;
 283 }
 284
 285 /*
 286  * Bitbang interface write of TCK, TMS, TDI
 287  *
 288  * Seeing as this is the only function where the outputs are changed,
 289  * we can cache the old value to avoid needlessly writing it.
 290  */
 291 static int sysfsgpio_write(int tck, int tms, int tdi)
 292 {
 293         const char one[] = "1";
 294         const char zero[] = "0";
 295
 296         static int last_tck;
 297         static int last_tms;
 298         static int last_tdi;
 299
 300         static int first_time;
 301         size_t bytes_written;
 302
 303         if (!first_time) {
 304                 last_tck = !tck;
 305                 last_tms = !tms;
 306                 last_tdi = !tdi;
 307                 first_time = 1;
 308         }
 309
 310         if (tdi != last_tdi) {
 311                 bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
 312                 if (bytes_written != 1)
 313                         LOG_WARNING("writing tdi failed");
 314         }
 315
 316         if (tms != last_tms) {
 317                 bytes_written = write(tms_fd, tms ? &one : &zero, 1);
 318                 if (bytes_written != 1)
 319                         LOG_WARNING("writing tms failed");
 320         }
 321
 322         /* write clk last */
 323         if (tck != last_tck) {
 324                 bytes_written = write(tck_fd, tck ? &one : &zero, 1);
 325                 if (bytes_written != 1)
 326                         LOG_WARNING("writing tck failed");
 327         }
 328
 329         last_tdi = tdi;
 330         last_tms = tms;
 331         last_tck = tck;
 332
 333         return ERROR_OK;
 334 }
 335
 336 /*
 337  * Bitbang interface to manipulate reset lines SRST and TRST
 338  *
 339  * (1) assert or (0) deassert reset lines
 340  */
 341 static int sysfsgpio_reset(int trst, int srst)
 342 {
 343         LOG_DEBUG("sysfsgpio_reset");
 344         const char one[] = "1";
 345         const char zero[] = "0";
 346         size_t bytes_written;
 347
 348         /* assume active low */
 349         if (srst_fd >= 0) {
 350                 bytes_written = write(srst_fd, srst ? &zero : &one, 1);
 351                 if (bytes_written != 1)
 352                         LOG_WARNING("writing srst failed");
 353         }
 354
 355         /* assume active low */
 356         if (trst_fd >= 0) {
 357                 bytes_written = write(trst_fd, trst ? &zero : &one, 1);
 358                 if (bytes_written != 1)
 359                         LOG_WARNING("writing trst failed");
 360         }
 361
 362         return ERROR_OK;
 363 }
 364
 365 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
 366 {
 367         if (CMD_ARGC == 4) {
 368                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 369                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
 370                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
 371                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
 372         } else if (CMD_ARGC != 0) {
 373                 return ERROR_COMMAND_SYNTAX_ERROR;
 374         }
 375
 376         command_print(CMD,
 377                         "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
 378                         tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
 379
 380         return ERROR_OK;
 381 }
 382
 383 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
 384 {
 385         if (CMD_ARGC == 1)
 386                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 387
 388         command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
 389         return ERROR_OK;
 390 }
 391
 392 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
 393 {
 394         if (CMD_ARGC == 1)
 395                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
 396
 397         command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
 398         return ERROR_OK;
 399 }
 400
 401 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
 402 {
 403         if (CMD_ARGC == 1)
 404                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
 405
 406         command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
 407         return ERROR_OK;
 408 }
 409
 410 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
 411 {
 412         if (CMD_ARGC == 1)
 413                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
 414
 415         command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
 416         return ERROR_OK;
 417 }
 418
 419 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
 420 {
 421         if (CMD_ARGC == 1)
 422                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
 423
 424         command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
 425         return ERROR_OK;
 426 }
 427
 428 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
 429 {
 430         if (CMD_ARGC == 1)
 431                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
 432
 433         command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
 434         return ERROR_OK;
 435 }
 436
 437 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
 438 {
 439         if (CMD_ARGC == 2) {
 440                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 441                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
 442         } else if (CMD_ARGC != 0) {
 443                 return ERROR_COMMAND_SYNTAX_ERROR;
 444         }
 445
 446         command_print(CMD,
 447                         "SysfsGPIO nums: swclk = %d, swdio = %d",
 448                         swclk_gpio, swdio_gpio);
 449
 450         return ERROR_OK;
 451 }
 452
 453 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
 454 {
 455         if (CMD_ARGC == 1)
 456                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 457
 458         command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
 459         return ERROR_OK;
 460 }
 461
 462 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
 463 {
 464         if (CMD_ARGC == 1)
 465                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
 466
 467         command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
 468         return ERROR_OK;
 469 }
 470
 471 static const struct command_registration sysfsgpio_subcommand_handlers[] = {
 472         {
 473                 .name = "jtag_nums",
 474                 .handler = &sysfsgpio_handle_jtag_gpionums,
 475                 .mode = COMMAND_CONFIG,
 476                 .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
 477                 .usage = "[tck tms tdi tdo]",
 478         },
 479         {
 480                 .name = "tck_num",
 481                 .handler = &sysfsgpio_handle_jtag_gpionum_tck,
 482                 .mode = COMMAND_CONFIG,
 483                 .help = "gpio number for tck.",
 484                 .usage = "[tck]",
 485         },
 486         {
 487                 .name = "tms_num",
 488                 .handler = &sysfsgpio_handle_jtag_gpionum_tms,
 489                 .mode = COMMAND_CONFIG,
 490                 .help = "gpio number for tms.",
 491                 .usage = "[tms]",
 492         },
 493         {
 494                 .name = "tdo_num",
 495                 .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
 496                 .mode = COMMAND_CONFIG,
 497                 .help = "gpio number for tdo.",
 498                 .usage = "[tdo]",
 499         },
 500         {
 501                 .name = "tdi_num",
 502                 .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
 503                 .mode = COMMAND_CONFIG,
 504                 .help = "gpio number for tdi.",
 505                 .usage = "[tdi]",
 506         },
 507         {
 508                 .name = "srst_num",
 509                 .handler = &sysfsgpio_handle_jtag_gpionum_srst,
 510                 .mode = COMMAND_CONFIG,
 511                 .help = "gpio number for srst.",
 512                 .usage = "[srst]",
 513         },
 514         {
 515                 .name = "trst_num",
 516                 .handler = &sysfsgpio_handle_jtag_gpionum_trst,
 517                 .mode = COMMAND_CONFIG,
 518                 .help = "gpio number for trst.",
 519                 .usage = "[trst]",
 520         },
 521         {
 522                 .name = "swd_nums",
 523                 .handler = &sysfsgpio_handle_swd_gpionums,
 524                 .mode = COMMAND_CONFIG,
 525                 .help = "gpio numbers for swclk, swdio. (in that order)",
 526                 .usage = "[swclk swdio]",
 527         },
 528         {
 529                 .name = "swclk_num",
 530                 .handler = &sysfsgpio_handle_swd_gpionum_swclk,
 531                 .mode = COMMAND_CONFIG,
 532                 .help = "gpio number for swclk.",
 533                 .usage = "[swclk]",
 534         },
 535         {
 536                 .name = "swdio_num",
 537                 .handler = &sysfsgpio_handle_swd_gpionum_swdio,
 538                 .mode = COMMAND_CONFIG,
 539                 .help = "gpio number for swdio.",
 540                 .usage = "[swdio]",
 541         },
 542         COMMAND_REGISTRATION_DONE
 543 };
 544
 545 static const struct command_registration sysfsgpio_command_handlers[] = {
 546         {
 547                 .name = "sysfsgpio",
 548                 .mode = COMMAND_ANY,
 549                 .help = "perform sysfsgpio management",
 550                 .chain = sysfsgpio_subcommand_handlers,
 551                 .usage = "",
 552         },
 553         COMMAND_REGISTRATION_DONE
 554 };
 555
 556 static int sysfsgpio_init(void);
 557 static int sysfsgpio_quit(void);
 558
 559 static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
 560
 561 static struct jtag_interface sysfsgpio_interface = {
 562         .supported = DEBUG_CAP_TMS_SEQ,
 563         .execute_queue = bitbang_execute_queue,
 564 };
 565
 566 struct adapter_driver sysfsgpio_adapter_driver = {
 567         .name = "sysfsgpio",
 568         .transports = sysfsgpio_transports,
 569         .commands = sysfsgpio_command_handlers,
 570
 571         .init = sysfsgpio_init,
 572         .quit = sysfsgpio_quit,
 573         .reset = sysfsgpio_reset,
 574
 575         .jtag_ops = &sysfsgpio_interface,
 576         .swd_ops = &bitbang_swd,
 577 };
 578
 579 static struct bitbang_interface sysfsgpio_bitbang = {
 580         .read = sysfsgpio_read,
 581         .write = sysfsgpio_write,
 582         .swdio_read = sysfsgpio_swdio_read,
 583         .swdio_drive = sysfsgpio_swdio_drive,
 584         .swd_write = sysfsgpio_swd_write,
 585         .blink = 0
 586 };
 587
 588 /* helper func to close and cleanup files only if they were valid/ used */
 589 static void cleanup_fd(int fd, int gpio)
 590 {
 591         if (gpio >= 0) {
 592                 if (fd >= 0)
 593                         close(fd);
 594
 595                 unexport_sysfs_gpio(gpio);
 596         }
 597 }
 598
 599 static void cleanup_all_fds(void)
 600 {
 601         if (transport_is_jtag()) {
 602                 cleanup_fd(tck_fd, tck_gpio);
 603                 cleanup_fd(tms_fd, tms_gpio);
 604                 cleanup_fd(tdi_fd, tdi_gpio);
 605                 cleanup_fd(tdo_fd, tdo_gpio);
 606                 cleanup_fd(trst_fd, trst_gpio);
 607         }
 608         if (transport_is_swd()) {
 609                 cleanup_fd(swclk_fd, swclk_gpio);
 610                 cleanup_fd(swdio_fd, swdio_gpio);
 611         }
 612         cleanup_fd(srst_fd, srst_gpio);
 613 }
 614
 615 static bool sysfsgpio_jtag_mode_possible(void)
 616 {
 617         if (!is_gpio_valid(tck_gpio))
 618                 return false;
 619         if (!is_gpio_valid(tms_gpio))
 620                 return false;
 621         if (!is_gpio_valid(tdi_gpio))
 622                 return false;
 623         if (!is_gpio_valid(tdo_gpio))
 624                 return false;
 625         return true;
 626 }
 627
 628 static bool sysfsgpio_swd_mode_possible(void)
 629 {
 630         if (!is_gpio_valid(swclk_gpio))
 631                 return false;
 632         if (!is_gpio_valid(swdio_gpio))
 633                 return false;
 634         return true;
 635 }
 636
 637 static int sysfsgpio_init(void)
 638 {
 639         bitbang_interface = &sysfsgpio_bitbang;
 640
 641         LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
 642
 643         /*
 644          * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
 645          * as outputs.  Drive TDI and TCK low, and TMS/TRST/SRST high.
 646          * For SWD, SWCLK and SWDIO are configures as output high.
 647          */
 648
 649         if (transport_is_jtag()) {
 650                 if (!sysfsgpio_jtag_mode_possible()) {
 651                         LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode");
 652                         return ERROR_JTAG_INIT_FAILED;
 653                 }
 654
 655                 tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
 656                 if (tck_fd < 0)
 657                         goto out_error;
 658
 659                 tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
 660                 if (tms_fd < 0)
 661                         goto out_error;
 662
 663                 tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
 664                 if (tdi_fd < 0)
 665                         goto out_error;
 666
 667                 tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
 668                 if (tdo_fd < 0)
 669                         goto out_error;
 670
 671                 /* assume active low*/
 672                 if (trst_gpio >= 0) {
 673                         trst_fd = setup_sysfs_gpio(trst_gpio, 1, 1);
 674                         if (trst_fd < 0)
 675                                 goto out_error;
 676                 }
 677         }
 678
 679         if (transport_is_swd()) {
 680                 if (!sysfsgpio_swd_mode_possible()) {
 681                         LOG_ERROR("Require swclk and swdio gpio for SWD mode");
 682                         return ERROR_JTAG_INIT_FAILED;
 683                 }
 684
 685                 swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
 686                 if (swclk_fd < 0)
 687                         goto out_error;
 688
 689                 swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
 690                 if (swdio_fd < 0)
 691                         goto out_error;
 692         }
 693
 694         /* assume active low*/
 695         if (srst_gpio >= 0) {
 696                 srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
 697                 if (srst_fd < 0)
 698                         goto out_error;
 699         }
 700
 701         return ERROR_OK;
 702
 703 out_error:
 704         cleanup_all_fds();
 705         return ERROR_JTAG_INIT_FAILED;
 706 }
 707
 708 static int sysfsgpio_quit(void)
 709 {
 710         cleanup_all_fds();
 711         return ERROR_OK;
 712 }