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 bool 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
 103 /*
 104  * Exports and sets up direction for gpio.
 105  * If the gpio is an output, it is initialized according to init_high,
 106  * otherwise it is ignored.
 107  *
 108  * If the gpio is already exported we just show a warning and continue; if
 109  * openocd happened to crash (or was killed by user) then the gpios will not
 110  * have been cleaned up.
 111  */
 112 static int setup_sysfs_gpio(int gpio, int is_output, int init_high)
 113 {
 114         struct timeval timeout, now;
 115         char buf[40];
 116         char gpiostr[5];
 117         int ret;
 118
 119         if (!is_gpio_valid(gpio))
 120                 return ERROR_OK;
 121
 122         snprintf(gpiostr, sizeof(gpiostr), "%d", gpio);
 123         ret = open_write_close("/sys/class/gpio/export", gpiostr);
 124         if (ret < 0) {
 125                 if (errno == EBUSY) {
 126                         LOG_WARNING("gpio %d is already exported", gpio);
 127                 } else {
 128                         LOG_ERROR("Couldn't export gpio %d", gpio);
 129                         perror("sysfsgpio: ");
 130                         return ERROR_FAIL;
 131                 }
 132         }
 133
 134         gettimeofday(&timeout, NULL);
 135         timeval_add_time(&timeout, 0, 500000);
 136
 137         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", gpio);
 138         for (;;) {
 139                 ret = open_write_close(buf, is_output ? (init_high ? "high" : "low") : "in");
 140                 if (ret >= 0 || errno != EACCES)
 141                         break;
 142                 gettimeofday(&now, NULL);
 143                 if (timeval_compare(&now, &timeout) >= 0)
 144                         break;
 145                 jtag_sleep(10000);
 146         }
 147         if (ret < 0) {
 148                 LOG_ERROR("Couldn't set direction for gpio %d", gpio);
 149                 perror("sysfsgpio: ");
 150                 unexport_sysfs_gpio(gpio);
 151                 return ERROR_FAIL;
 152         }
 153
 154         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/value", gpio);
 155         for (;;) {
 156                 ret = open(buf, O_RDWR | O_NONBLOCK | O_SYNC);
 157                 if (ret >= 0 || errno != EACCES)
 158                         break;
 159                 gettimeofday(&now, NULL);
 160                 if (timeval_compare(&now, &timeout) >= 0)
 161                         break;
 162                 jtag_sleep(10000);
 163         }
 164         if (ret < 0) {
 165                 LOG_ERROR("Couldn't open value for gpio %d", gpio);
 166                 perror("sysfsgpio: ");
 167                 unexport_sysfs_gpio(gpio);
 168         }
 169
 170         return ret;
 171 }
 172
 173 /* gpio numbers for each gpio. Negative values are invalid */
 174 static int tck_gpio = -1;
 175 static int tms_gpio = -1;
 176 static int tdi_gpio = -1;
 177 static int tdo_gpio = -1;
 178 static int trst_gpio = -1;
 179 static int srst_gpio = -1;
 180 static int swclk_gpio = -1;
 181 static int swdio_gpio = -1;
 182
 183 /*
 184  * file descriptors for /sys/class/gpio/gpioXX/value
 185  * Set up during init.
 186  */
 187 static int tck_fd = -1;
 188 static int tms_fd = -1;
 189 static int tdi_fd = -1;
 190 static int tdo_fd = -1;
 191 static int trst_fd = -1;
 192 static int srst_fd = -1;
 193 static int swclk_fd = -1;
 194 static int swdio_fd = -1;
 195
 196 static int last_swclk;
 197 static int last_swdio;
 198 static bool last_stored;
 199 static bool swdio_input;
 200
 201 static void sysfsgpio_swdio_drive(bool is_output)
 202 {
 203         char buf[40];
 204         int ret;
 205
 206         snprintf(buf, sizeof(buf), "/sys/class/gpio/gpio%d/direction", swdio_gpio);
 207         ret = open_write_close(buf, is_output ? "high" : "in");
 208         if (ret < 0) {
 209                 LOG_ERROR("Couldn't set direction for gpio %d", swdio_gpio);
 210                 perror("sysfsgpio: ");
 211         }
 212
 213         last_stored = false;
 214         swdio_input = !is_output;
 215 }
 216
 217 static int sysfsgpio_swdio_read(void)
 218 {
 219         char buf[1];
 220
 221         /* important to seek to signal sysfs of new read */
 222         lseek(swdio_fd, 0, SEEK_SET);
 223         int ret = read(swdio_fd, &buf, sizeof(buf));
 224
 225         if (ret < 0) {
 226                 LOG_WARNING("reading swdio failed");
 227                 return 0;
 228         }
 229
 230         return buf[0] != '0';
 231 }
 232
 233 static void sysfsgpio_swdio_write(int swclk, int swdio)
 234 {
 235         const char one[] = "1";
 236         const char zero[] = "0";
 237
 238         size_t bytes_written;
 239
 240         if (!swdio_input) {
 241                 if (!last_stored || (swdio != last_swdio)) {
 242                         bytes_written = write(swdio_fd, swdio ? &one : &zero, 1);
 243                         if (bytes_written != 1)
 244                                 LOG_WARNING("writing swdio failed");
 245                 }
 246         }
 247
 248         /* write swclk last */
 249         if (!last_stored || (swclk != last_swclk)) {
 250                 bytes_written = write(swclk_fd, swclk ? &one : &zero, 1);
 251                 if (bytes_written != 1)
 252                         LOG_WARNING("writing swclk failed");
 253         }
 254
 255         last_swdio = swdio;
 256         last_swclk = swclk;
 257         last_stored = true;
 258 }
 259
 260 /*
 261  * Bitbang interface read of TDO
 262  *
 263  * The sysfs value will read back either '0' or '1'. The trick here is to call
 264  * lseek to bypass buffering in the sysfs kernel driver.
 265  */
 266 static bb_value_t sysfsgpio_read(void)
 267 {
 268         char buf[1];
 269
 270         /* important to seek to signal sysfs of new read */
 271         lseek(tdo_fd, 0, SEEK_SET);
 272         int ret = read(tdo_fd, &buf, sizeof(buf));
 273
 274         if (ret < 0) {
 275                 LOG_WARNING("reading tdo failed");
 276                 return 0;
 277         }
 278
 279         return buf[0] == '0' ? BB_LOW : BB_HIGH;
 280 }
 281
 282 /*
 283  * Bitbang interface write of TCK, TMS, TDI
 284  *
 285  * Seeing as this is the only function where the outputs are changed,
 286  * we can cache the old value to avoid needlessly writing it.
 287  */
 288 static int sysfsgpio_write(int tck, int tms, int tdi)
 289 {
 290         if (swd_mode) {
 291                 sysfsgpio_swdio_write(tck, tdi);
 292                 return ERROR_OK;
 293         }
 294
 295         const char one[] = "1";
 296         const char zero[] = "0";
 297
 298         static int last_tck;
 299         static int last_tms;
 300         static int last_tdi;
 301
 302         static int first_time;
 303         size_t bytes_written;
 304
 305         if (!first_time) {
 306                 last_tck = !tck;
 307                 last_tms = !tms;
 308                 last_tdi = !tdi;
 309                 first_time = 1;
 310         }
 311
 312         if (tdi != last_tdi) {
 313                 bytes_written = write(tdi_fd, tdi ? &one : &zero, 1);
 314                 if (bytes_written != 1)
 315                         LOG_WARNING("writing tdi failed");
 316         }
 317
 318         if (tms != last_tms) {
 319                 bytes_written = write(tms_fd, tms ? &one : &zero, 1);
 320                 if (bytes_written != 1)
 321                         LOG_WARNING("writing tms failed");
 322         }
 323
 324         /* write clk last */
 325         if (tck != last_tck) {
 326                 bytes_written = write(tck_fd, tck ? &one : &zero, 1);
 327                 if (bytes_written != 1)
 328                         LOG_WARNING("writing tck failed");
 329         }
 330
 331         last_tdi = tdi;
 332         last_tms = tms;
 333         last_tck = tck;
 334
 335         return ERROR_OK;
 336 }
 337
 338 /*
 339  * Bitbang interface to manipulate reset lines SRST and TRST
 340  *
 341  * (1) assert or (0) deassert reset lines
 342  */
 343 static int sysfsgpio_reset(int trst, int srst)
 344 {
 345         LOG_DEBUG("sysfsgpio_reset");
 346         const char one[] = "1";
 347         const char zero[] = "0";
 348         size_t bytes_written;
 349
 350         /* assume active low */
 351         if (srst_fd >= 0) {
 352                 bytes_written = write(srst_fd, srst ? &zero : &one, 1);
 353                 if (bytes_written != 1)
 354                         LOG_WARNING("writing srst failed");
 355         }
 356
 357         /* assume active low */
 358         if (trst_fd >= 0) {
 359                 bytes_written = write(trst_fd, trst ? &zero : &one, 1);
 360                 if (bytes_written != 1)
 361                         LOG_WARNING("writing trst failed");
 362         }
 363
 364         return ERROR_OK;
 365 }
 366
 367 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionums)
 368 {
 369         if (CMD_ARGC == 4) {
 370                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 371                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
 372                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
 373                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
 374         } else if (CMD_ARGC != 0) {
 375                 return ERROR_COMMAND_SYNTAX_ERROR;
 376         }
 377
 378         command_print(CMD,
 379                         "SysfsGPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
 380                         tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
 381
 382         return ERROR_OK;
 383 }
 384
 385 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tck)
 386 {
 387         if (CMD_ARGC == 1)
 388                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 389
 390         command_print(CMD, "SysfsGPIO num: tck = %d", tck_gpio);
 391         return ERROR_OK;
 392 }
 393
 394 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tms)
 395 {
 396         if (CMD_ARGC == 1)
 397                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
 398
 399         command_print(CMD, "SysfsGPIO num: tms = %d", tms_gpio);
 400         return ERROR_OK;
 401 }
 402
 403 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdo)
 404 {
 405         if (CMD_ARGC == 1)
 406                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
 407
 408         command_print(CMD, "SysfsGPIO num: tdo = %d", tdo_gpio);
 409         return ERROR_OK;
 410 }
 411
 412 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_tdi)
 413 {
 414         if (CMD_ARGC == 1)
 415                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
 416
 417         command_print(CMD, "SysfsGPIO num: tdi = %d", tdi_gpio);
 418         return ERROR_OK;
 419 }
 420
 421 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_srst)
 422 {
 423         if (CMD_ARGC == 1)
 424                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
 425
 426         command_print(CMD, "SysfsGPIO num: srst = %d", srst_gpio);
 427         return ERROR_OK;
 428 }
 429
 430 COMMAND_HANDLER(sysfsgpio_handle_jtag_gpionum_trst)
 431 {
 432         if (CMD_ARGC == 1)
 433                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
 434
 435         command_print(CMD, "SysfsGPIO num: trst = %d", trst_gpio);
 436         return ERROR_OK;
 437 }
 438
 439 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionums)
 440 {
 441         if (CMD_ARGC == 2) {
 442                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 443                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
 444         } else if (CMD_ARGC != 0) {
 445                 return ERROR_COMMAND_SYNTAX_ERROR;
 446         }
 447
 448         command_print(CMD,
 449                         "SysfsGPIO nums: swclk = %d, swdio = %d",
 450                         swclk_gpio, swdio_gpio);
 451
 452         return ERROR_OK;
 453 }
 454
 455 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swclk)
 456 {
 457         if (CMD_ARGC == 1)
 458                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 459
 460         command_print(CMD, "SysfsGPIO num: swclk = %d", swclk_gpio);
 461         return ERROR_OK;
 462 }
 463
 464 COMMAND_HANDLER(sysfsgpio_handle_swd_gpionum_swdio)
 465 {
 466         if (CMD_ARGC == 1)
 467                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
 468
 469         command_print(CMD, "SysfsGPIO num: swdio = %d", swdio_gpio);
 470         return ERROR_OK;
 471 }
 472
 473 static const struct command_registration sysfsgpio_command_handlers[] = {
 474         {
 475                 .name = "sysfsgpio_jtag_nums",
 476                 .handler = &sysfsgpio_handle_jtag_gpionums,
 477                 .mode = COMMAND_CONFIG,
 478                 .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
 479                 .usage = "[tck tms tdi tdo]",
 480         },
 481         {
 482                 .name = "sysfsgpio_tck_num",
 483                 .handler = &sysfsgpio_handle_jtag_gpionum_tck,
 484                 .mode = COMMAND_CONFIG,
 485                 .help = "gpio number for tck.",
 486                 .usage = "[tck]",
 487         },
 488         {
 489                 .name = "sysfsgpio_tms_num",
 490                 .handler = &sysfsgpio_handle_jtag_gpionum_tms,
 491                 .mode = COMMAND_CONFIG,
 492                 .help = "gpio number for tms.",
 493                 .usage = "[tms]",
 494         },
 495         {
 496                 .name = "sysfsgpio_tdo_num",
 497                 .handler = &sysfsgpio_handle_jtag_gpionum_tdo,
 498                 .mode = COMMAND_CONFIG,
 499                 .help = "gpio number for tdo.",
 500                 .usage = "[tdo]",
 501         },
 502         {
 503                 .name = "sysfsgpio_tdi_num",
 504                 .handler = &sysfsgpio_handle_jtag_gpionum_tdi,
 505                 .mode = COMMAND_CONFIG,
 506                 .help = "gpio number for tdi.",
 507                 .usage = "[tdi]",
 508         },
 509         {
 510                 .name = "sysfsgpio_srst_num",
 511                 .handler = &sysfsgpio_handle_jtag_gpionum_srst,
 512                 .mode = COMMAND_CONFIG,
 513                 .help = "gpio number for srst.",
 514                 .usage = "[srst]",
 515         },
 516         {
 517                 .name = "sysfsgpio_trst_num",
 518                 .handler = &sysfsgpio_handle_jtag_gpionum_trst,
 519                 .mode = COMMAND_CONFIG,
 520                 .help = "gpio number for trst.",
 521                 .usage = "[trst]",
 522         },
 523         {
 524                 .name = "sysfsgpio_swd_nums",
 525                 .handler = &sysfsgpio_handle_swd_gpionums,
 526                 .mode = COMMAND_CONFIG,
 527                 .help = "gpio numbers for swclk, swdio. (in that order)",
 528                 .usage = "[swclk swdio]",
 529         },
 530         {
 531                 .name = "sysfsgpio_swclk_num",
 532                 .handler = &sysfsgpio_handle_swd_gpionum_swclk,
 533                 .mode = COMMAND_CONFIG,
 534                 .help = "gpio number for swclk.",
 535                 .usage = "[swclk]",
 536         },
 537         {
 538                 .name = "sysfsgpio_swdio_num",
 539                 .handler = &sysfsgpio_handle_swd_gpionum_swdio,
 540                 .mode = COMMAND_CONFIG,
 541                 .help = "gpio number for swdio.",
 542                 .usage = "[swdio]",
 543         },
 544         COMMAND_REGISTRATION_DONE
 545 };
 546
 547 static int sysfsgpio_init(void);
 548 static int sysfsgpio_quit(void);
 549
 550 static const char * const sysfsgpio_transports[] = { "jtag", "swd", NULL };
 551
 552 static struct jtag_interface sysfsgpio_interface = {
 553         .supported = DEBUG_CAP_TMS_SEQ,
 554         .execute_queue = bitbang_execute_queue,
 555 };
 556
 557 struct adapter_driver sysfsgpio_adapter_driver = {
 558         .name = "sysfsgpio",
 559         .transports = sysfsgpio_transports,
 560         .commands = sysfsgpio_command_handlers,
 561
 562         .init = sysfsgpio_init,
 563         .quit = sysfsgpio_quit,
 564         .reset = sysfsgpio_reset,
 565
 566         .jtag_ops = &sysfsgpio_interface,
 567         .swd_ops = &bitbang_swd,
 568 };
 569
 570 static struct bitbang_interface sysfsgpio_bitbang = {
 571         .read = sysfsgpio_read,
 572         .write = sysfsgpio_write,
 573         .swdio_read = sysfsgpio_swdio_read,
 574         .swdio_drive = sysfsgpio_swdio_drive,
 575         .blink = 0
 576 };
 577
 578 /* helper func to close and cleanup files only if they were valid/ used */
 579 static void cleanup_fd(int fd, int gpio)
 580 {
 581         if (gpio >= 0) {
 582                 if (fd >= 0)
 583                         close(fd);
 584
 585                 unexport_sysfs_gpio(gpio);
 586         }
 587 }
 588
 589 static void cleanup_all_fds(void)
 590 {
 591         cleanup_fd(tck_fd, tck_gpio);
 592         cleanup_fd(tms_fd, tms_gpio);
 593         cleanup_fd(tdi_fd, tdi_gpio);
 594         cleanup_fd(tdo_fd, tdo_gpio);
 595         cleanup_fd(trst_fd, trst_gpio);
 596         cleanup_fd(srst_fd, srst_gpio);
 597         cleanup_fd(swclk_fd, swclk_gpio);
 598         cleanup_fd(swdio_fd, swdio_gpio);
 599 }
 600
 601 static bool sysfsgpio_jtag_mode_possible(void)
 602 {
 603         if (!is_gpio_valid(tck_gpio))
 604                 return false;
 605         if (!is_gpio_valid(tms_gpio))
 606                 return false;
 607         if (!is_gpio_valid(tdi_gpio))
 608                 return false;
 609         if (!is_gpio_valid(tdo_gpio))
 610                 return false;
 611         return true;
 612 }
 613
 614 static bool sysfsgpio_swd_mode_possible(void)
 615 {
 616         if (!is_gpio_valid(swclk_gpio))
 617                 return false;
 618         if (!is_gpio_valid(swdio_gpio))
 619                 return false;
 620         return true;
 621 }
 622
 623 static int sysfsgpio_init(void)
 624 {
 625         bitbang_interface = &sysfsgpio_bitbang;
 626
 627         LOG_INFO("SysfsGPIO JTAG/SWD bitbang driver");
 628
 629         if (sysfsgpio_jtag_mode_possible()) {
 630                 if (sysfsgpio_swd_mode_possible())
 631                         LOG_INFO("JTAG and SWD modes enabled");
 632                 else
 633                         LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
 634         } else if (sysfsgpio_swd_mode_possible()) {
 635                 LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
 636         } else {
 637                 LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
 638                 return ERROR_JTAG_INIT_FAILED;
 639         }
 640
 641
 642         /*
 643          * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
 644          * as outputs.  Drive TDI and TCK low, and TMS/TRST/SRST high.
 645          * For SWD, SWCLK and SWDIO are configures as output high.
 646          */
 647         if (tck_gpio >= 0) {
 648                 tck_fd = setup_sysfs_gpio(tck_gpio, 1, 0);
 649                 if (tck_fd < 0)
 650                         goto out_error;
 651         }
 652
 653         if (tms_gpio >= 0) {
 654                 tms_fd = setup_sysfs_gpio(tms_gpio, 1, 1);
 655                 if (tms_fd < 0)
 656                         goto out_error;
 657         }
 658
 659         if (tdi_gpio >= 0) {
 660                 tdi_fd = setup_sysfs_gpio(tdi_gpio, 1, 0);
 661                 if (tdi_fd < 0)
 662                         goto out_error;
 663         }
 664
 665         if (tdo_gpio >= 0) {
 666                 tdo_fd = setup_sysfs_gpio(tdo_gpio, 0, 0);
 667                 if (tdo_fd < 0)
 668                         goto out_error;
 669         }
 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         /* assume active low*/
 679         if (srst_gpio >= 0) {
 680                 srst_fd = setup_sysfs_gpio(srst_gpio, 1, 1);
 681                 if (srst_fd < 0)
 682                         goto out_error;
 683         }
 684
 685         if (swclk_gpio >= 0) {
 686                 swclk_fd = setup_sysfs_gpio(swclk_gpio, 1, 0);
 687                 if (swclk_fd < 0)
 688                         goto out_error;
 689         }
 690
 691         if (swdio_gpio >= 0) {
 692                 swdio_fd = setup_sysfs_gpio(swdio_gpio, 1, 0);
 693                 if (swdio_fd < 0)
 694                         goto out_error;
 695         }
 696
 697         return ERROR_OK;
 698
 699 out_error:
 700         cleanup_all_fds();
 701         return ERROR_JTAG_INIT_FAILED;
 702 }
 703
 704 static int sysfsgpio_quit(void)
 705 {
 706         cleanup_all_fds();
 707         return ERROR_OK;
 708 }