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   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Bitbang driver for Linux GPIO descriptors through libgpiod
   4  * Copyright (C) 2020 Antonio Borneo <borneo.antonio@gmail.com>
   5  *
   6  * Largely based on sysfsgpio driver
   7  * Copyright (C) 2012 by Creative Product Design, marc @ cpdesign.com.au
   8  * Copyright (C) 2014 by Jean-Christian de Rivaz <jc@eclis.ch>
   9  * Copyright (C) 2014 by Paul Fertser <fercerpav@gmail.com>
  10  */
  11
  12 #ifdef HAVE_CONFIG_H
  13 #include "config.h"
  14 #endif
  15
  16 #include <gpiod.h>
  17 #include <jtag/interface.h>
  18 #include <transport/transport.h>
  19 #include "bitbang.h"
  20
  21 /* gpio numbers for each gpio. Negative values are invalid */
  22 static int tck_gpio = -1;
  23 static int tms_gpio = -1;
  24 static int tdi_gpio = -1;
  25 static int tdo_gpio = -1;
  26 static int trst_gpio = -1;
  27 static int srst_gpio = -1;
  28 static int swclk_gpio = -1;
  29 static int swdio_gpio = -1;
  30 static int led_gpio = -1;
  31 static int gpiochip = -1;
  32
  33 static struct gpiod_chip *gpiod_chip;
  34 static struct gpiod_line *gpiod_tck;
  35 static struct gpiod_line *gpiod_tms;
  36 static struct gpiod_line *gpiod_tdi;
  37 static struct gpiod_line *gpiod_tdo;
  38 static struct gpiod_line *gpiod_trst;
  39 static struct gpiod_line *gpiod_swclk;
  40 static struct gpiod_line *gpiod_swdio;
  41 static struct gpiod_line *gpiod_srst;
  42 static struct gpiod_line *gpiod_led;
  43
  44 static int last_swclk;
  45 static int last_swdio;
  46 static bool last_stored;
  47 static bool swdio_input;
  48
  49 /* Bitbang interface read of TDO */
  50 static bb_value_t linuxgpiod_read(void)
  51 {
  52         int retval;
  53
  54         retval = gpiod_line_get_value(gpiod_tdo);
  55         if (retval < 0) {
  56                 LOG_WARNING("reading tdo failed");
  57                 return 0;
  58         }
  59
  60         return retval ? BB_HIGH : BB_LOW;
  61 }
  62
  63 /*
  64  * Bitbang interface write of TCK, TMS, TDI
  65  *
  66  * Seeing as this is the only function where the outputs are changed,
  67  * we can cache the old value to avoid needlessly writing it.
  68  */
  69 static int linuxgpiod_write(int tck, int tms, int tdi)
  70 {
  71         static int last_tck;
  72         static int last_tms;
  73         static int last_tdi;
  74
  75         static int first_time;
  76
  77         int retval;
  78
  79         if (!first_time) {
  80                 last_tck = !tck;
  81                 last_tms = !tms;
  82                 last_tdi = !tdi;
  83                 first_time = 1;
  84         }
  85
  86         if (tdi != last_tdi) {
  87                 retval = gpiod_line_set_value(gpiod_tdi, tdi);
  88                 if (retval < 0)
  89                         LOG_WARNING("writing tdi failed");
  90         }
  91
  92         if (tms != last_tms) {
  93                 retval = gpiod_line_set_value(gpiod_tms, tms);
  94                 if (retval < 0)
  95                         LOG_WARNING("writing tms failed");
  96         }
  97
  98         /* write clk last */
  99         if (tck != last_tck) {
 100                 retval = gpiod_line_set_value(gpiod_tck, tck);
 101                 if (retval < 0)
 102                         LOG_WARNING("writing tck failed");
 103         }
 104
 105         last_tdi = tdi;
 106         last_tms = tms;
 107         last_tck = tck;
 108
 109         return ERROR_OK;
 110 }
 111
 112 static int linuxgpiod_swdio_read(void)
 113 {
 114         int retval;
 115
 116         retval = gpiod_line_get_value(gpiod_swdio);
 117         if (retval < 0) {
 118                 LOG_WARNING("Fail read swdio");
 119                 return 0;
 120         }
 121
 122         return retval;
 123 }
 124
 125 static void linuxgpiod_swdio_drive(bool is_output)
 126 {
 127         int retval;
 128
 129         /*
 130          * FIXME: change direction requires release and re-require the line
 131          * https://stackoverflow.com/questions/58735140/
 132          * this would change in future libgpiod
 133          */
 134         gpiod_line_release(gpiod_swdio);
 135
 136         if (is_output) {
 137                 retval = gpiod_line_request_output(gpiod_swdio, "OpenOCD", 1);
 138                 if (retval < 0)
 139                         LOG_WARNING("Fail request_output line swdio");
 140         } else {
 141                 retval = gpiod_line_request_input(gpiod_swdio, "OpenOCD");
 142                 if (retval < 0)
 143                         LOG_WARNING("Fail request_input line swdio");
 144         }
 145
 146         last_stored = false;
 147         swdio_input = !is_output;
 148 }
 149
 150 static int linuxgpiod_swd_write(int swclk, int swdio)
 151 {
 152         int retval;
 153
 154         if (!swdio_input) {
 155                 if (!last_stored || (swdio != last_swdio)) {
 156                         retval = gpiod_line_set_value(gpiod_swdio, swdio);
 157                         if (retval < 0)
 158                                 LOG_WARNING("Fail set swdio");
 159                 }
 160         }
 161
 162         /* write swclk last */
 163         if (!last_stored || (swclk != last_swclk)) {
 164                 retval = gpiod_line_set_value(gpiod_swclk, swclk);
 165                 if (retval < 0)
 166                         LOG_WARNING("Fail set swclk");
 167         }
 168
 169         last_swdio = swdio;
 170         last_swclk = swclk;
 171         last_stored = true;
 172
 173         return ERROR_OK;
 174 }
 175
 176 static int linuxgpiod_blink(int on)
 177 {
 178         int retval;
 179
 180         if (!gpiod_led)
 181                 return ERROR_OK;
 182
 183         retval = gpiod_line_set_value(gpiod_led, on);
 184         if (retval < 0)
 185                 LOG_WARNING("Fail set led");
 186         return retval;
 187 }
 188
 189 static struct bitbang_interface linuxgpiod_bitbang = {
 190         .read = linuxgpiod_read,
 191         .write = linuxgpiod_write,
 192         .swdio_read = linuxgpiod_swdio_read,
 193         .swdio_drive = linuxgpiod_swdio_drive,
 194         .swd_write = linuxgpiod_swd_write,
 195         .blink = linuxgpiod_blink,
 196 };
 197
 198 /*
 199  * Bitbang interface to manipulate reset lines SRST and TRST
 200  *
 201  * (1) assert or (0) deassert reset lines
 202  */
 203 static int linuxgpiod_reset(int trst, int srst)
 204 {
 205         int retval1 = 0, retval2 = 0;
 206
 207         LOG_DEBUG("linuxgpiod_reset");
 208
 209         /* assume active low */
 210         if (gpiod_srst) {
 211                 retval1 = gpiod_line_set_value(gpiod_srst, srst ? 0 : 1);
 212                 if (retval1 < 0)
 213                         LOG_WARNING("set srst value failed");
 214         }
 215
 216         /* assume active low */
 217         if (gpiod_trst) {
 218                 retval2 = gpiod_line_set_value(gpiod_trst, trst ? 0 : 1);
 219                 if (retval2 < 0)
 220                         LOG_WARNING("set trst value failed");
 221         }
 222
 223         return ((retval1 < 0) || (retval2 < 0)) ? ERROR_FAIL : ERROR_OK;
 224 }
 225
 226 /*
 227  * Helper function to determine if gpio number is valid
 228  *
 229  * Assume here that there will be less than 10000 gpios per gpiochip
 230  */
 231 static bool is_gpio_valid(int gpio)
 232 {
 233         return gpio >= 0 && gpio < 10000;
 234 }
 235
 236 static bool linuxgpiod_jtag_mode_possible(void)
 237 {
 238         if (!is_gpio_valid(tck_gpio))
 239                 return false;
 240         if (!is_gpio_valid(tms_gpio))
 241                 return false;
 242         if (!is_gpio_valid(tdi_gpio))
 243                 return false;
 244         if (!is_gpio_valid(tdo_gpio))
 245                 return false;
 246         return true;
 247 }
 248
 249 static bool linuxgpiod_swd_mode_possible(void)
 250 {
 251         if (!is_gpio_valid(swclk_gpio))
 252                 return false;
 253         if (!is_gpio_valid(swdio_gpio))
 254                 return false;
 255         return true;
 256 }
 257
 258 static inline void helper_release(struct gpiod_line *line)
 259 {
 260         if (line)
 261                 gpiod_line_release(line);
 262 }
 263
 264 static int linuxgpiod_quit(void)
 265 {
 266         helper_release(gpiod_led);
 267         helper_release(gpiod_srst);
 268         helper_release(gpiod_swdio);
 269         helper_release(gpiod_swclk);
 270         helper_release(gpiod_trst);
 271         helper_release(gpiod_tms);
 272         helper_release(gpiod_tck);
 273         helper_release(gpiod_tdi);
 274         helper_release(gpiod_tdo);
 275
 276         gpiod_chip_close(gpiod_chip);
 277
 278         return ERROR_OK;
 279 }
 280
 281 static struct gpiod_line *helper_get_line(const char *label, unsigned int offset, int val, int dir, int flags)
 282 {
 283         struct gpiod_line *line;
 284         int retval;
 285
 286         line = gpiod_chip_get_line(gpiod_chip, offset);
 287         if (!line) {
 288                 LOG_ERROR("Error get line %s", label);
 289                 return NULL;
 290         }
 291
 292         struct gpiod_line_request_config config = {
 293                 .consumer = "OpenOCD",
 294                 .request_type = dir,
 295                 .flags = flags,
 296         };
 297
 298         retval = gpiod_line_request(line, &config, val);
 299         if (retval < 0) {
 300                 LOG_ERROR("Error requesting gpio line %s", label);
 301                 return NULL;
 302         }
 303
 304         return line;
 305 }
 306
 307 static struct gpiod_line *helper_get_input_line(const char *label, unsigned int offset)
 308 {
 309         return helper_get_line(label, offset, 0, GPIOD_LINE_REQUEST_DIRECTION_INPUT, 0);
 310 }
 311
 312 static struct gpiod_line *helper_get_output_line(const char *label, unsigned int offset, int val)
 313 {
 314         return helper_get_line(label, offset, val, GPIOD_LINE_REQUEST_DIRECTION_OUTPUT, 0);
 315 }
 316
 317 static struct gpiod_line *helper_get_open_drain_output_line(const char *label, unsigned int offset, int val)
 318 {
 319         return helper_get_line(label, offset, val, GPIOD_LINE_REQUEST_DIRECTION_OUTPUT, GPIOD_LINE_REQUEST_FLAG_OPEN_DRAIN);
 320 }
 321
 322 static int linuxgpiod_init(void)
 323 {
 324         LOG_INFO("Linux GPIOD JTAG/SWD bitbang driver");
 325
 326         bitbang_interface = &linuxgpiod_bitbang;
 327
 328         gpiod_chip = gpiod_chip_open_by_number(gpiochip);
 329         if (!gpiod_chip) {
 330                 LOG_ERROR("Cannot open LinuxGPIOD gpiochip %d", gpiochip);
 331                 return ERROR_JTAG_INIT_FAILED;
 332         }
 333
 334         /*
 335          * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
 336          * as outputs.  Drive TDI and TCK low, and TMS/TRST/SRST high.
 337          * For SWD, SWCLK and SWDIO are configures as output high.
 338          */
 339
 340         if (transport_is_jtag()) {
 341                 if (!linuxgpiod_jtag_mode_possible()) {
 342                         LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode");
 343                         goto out_error;
 344                 }
 345
 346                 gpiod_tdo = helper_get_input_line("tdo", tdo_gpio);
 347                 if (!gpiod_tdo)
 348                         goto out_error;
 349
 350                 gpiod_tdi = helper_get_output_line("tdi", tdi_gpio, 0);
 351                 if (!gpiod_tdi)
 352                         goto out_error;
 353
 354                 gpiod_tck = helper_get_output_line("tck", tck_gpio, 0);
 355                 if (!gpiod_tck)
 356                         goto out_error;
 357
 358                 gpiod_tms = helper_get_output_line("tms", tms_gpio, 1);
 359                 if (!gpiod_tms)
 360                         goto out_error;
 361
 362                 if (is_gpio_valid(trst_gpio)) {
 363                         if (jtag_get_reset_config() & RESET_TRST_OPEN_DRAIN)
 364                                 gpiod_trst = helper_get_open_drain_output_line("trst", trst_gpio, 1);
 365                         else
 366                                 gpiod_trst = helper_get_output_line("trst", trst_gpio, 1);
 367
 368                         if (!gpiod_trst)
 369                                 goto out_error;
 370                 }
 371         }
 372
 373         if (transport_is_swd()) {
 374                 if (!linuxgpiod_swd_mode_possible()) {
 375                         LOG_ERROR("Require swclk and swdio gpio for SWD mode");
 376                         goto out_error;
 377                 }
 378
 379                 gpiod_swclk = helper_get_output_line("swclk", swclk_gpio, 1);
 380                 if (!gpiod_swclk)
 381                         goto out_error;
 382
 383                 gpiod_swdio = helper_get_output_line("swdio", swdio_gpio, 1);
 384                 if (!gpiod_swdio)
 385                         goto out_error;
 386         }
 387
 388         if (is_gpio_valid(srst_gpio)) {
 389                 if (jtag_get_reset_config() & RESET_SRST_PUSH_PULL)
 390                         gpiod_srst = helper_get_output_line("srst", srst_gpio, 1);
 391                 else
 392                         gpiod_srst = helper_get_open_drain_output_line("srst", srst_gpio, 1);
 393
 394                 if (!gpiod_srst)
 395                         goto out_error;
 396         }
 397
 398         if (is_gpio_valid(led_gpio)) {
 399                 gpiod_led = helper_get_output_line("led", led_gpio, 0);
 400                 if (!gpiod_led)
 401                         goto out_error;
 402         }
 403
 404         return ERROR_OK;
 405
 406 out_error:
 407         linuxgpiod_quit();
 408
 409         return ERROR_JTAG_INIT_FAILED;
 410 }
 411
 412 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionums)
 413 {
 414         if (CMD_ARGC == 4) {
 415                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 416                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
 417                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
 418                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
 419         } else if (CMD_ARGC != 0) {
 420                 return ERROR_COMMAND_SYNTAX_ERROR;
 421         }
 422
 423         command_print(CMD,
 424                         "LinuxGPIOD nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
 425                         tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);
 426
 427         return ERROR_OK;
 428 }
 429
 430 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_tck)
 431 {
 432         if (CMD_ARGC == 1)
 433                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
 434
 435         command_print(CMD, "LinuxGPIOD num: tck = %d", tck_gpio);
 436         return ERROR_OK;
 437 }
 438
 439 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_tms)
 440 {
 441         if (CMD_ARGC == 1)
 442                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);
 443
 444         command_print(CMD, "LinuxGPIOD num: tms = %d", tms_gpio);
 445         return ERROR_OK;
 446 }
 447
 448 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_tdo)
 449 {
 450         if (CMD_ARGC == 1)
 451                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);
 452
 453         command_print(CMD, "LinuxGPIOD num: tdo = %d", tdo_gpio);
 454         return ERROR_OK;
 455 }
 456
 457 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_tdi)
 458 {
 459         if (CMD_ARGC == 1)
 460                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);
 461
 462         command_print(CMD, "LinuxGPIOD num: tdi = %d", tdi_gpio);
 463         return ERROR_OK;
 464 }
 465
 466 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_srst)
 467 {
 468         if (CMD_ARGC == 1)
 469                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);
 470
 471         command_print(CMD, "LinuxGPIOD num: srst = %d", srst_gpio);
 472         return ERROR_OK;
 473 }
 474
 475 COMMAND_HANDLER(linuxgpiod_handle_jtag_gpionum_trst)
 476 {
 477         if (CMD_ARGC == 1)
 478                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);
 479
 480         command_print(CMD, "LinuxGPIOD num: trst = %d", trst_gpio);
 481         return ERROR_OK;
 482 }
 483
 484 COMMAND_HANDLER(linuxgpiod_handle_swd_gpionums)
 485 {
 486         if (CMD_ARGC == 2) {
 487                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 488                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
 489         } else if (CMD_ARGC != 0) {
 490                 return ERROR_COMMAND_SYNTAX_ERROR;
 491         }
 492
 493         command_print(CMD,
 494                         "LinuxGPIOD nums: swclk = %d, swdio = %d",
 495                         swclk_gpio, swdio_gpio);
 496
 497         return ERROR_OK;
 498 }
 499
 500 COMMAND_HANDLER(linuxgpiod_handle_swd_gpionum_swclk)
 501 {
 502         if (CMD_ARGC == 1)
 503                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
 504
 505         command_print(CMD, "LinuxGPIOD num: swclk = %d", swclk_gpio);
 506         return ERROR_OK;
 507 }
 508
 509 COMMAND_HANDLER(linuxgpiod_handle_swd_gpionum_swdio)
 510 {
 511         if (CMD_ARGC == 1)
 512                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);
 513
 514         command_print(CMD, "LinuxGPIOD num: swdio = %d", swdio_gpio);
 515         return ERROR_OK;
 516 }
 517
 518 COMMAND_HANDLER(linuxgpiod_handle_gpionum_led)
 519 {
 520         if (CMD_ARGC == 1)
 521                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], led_gpio);
 522
 523         command_print(CMD, "LinuxGPIOD num: led = %d", led_gpio);
 524         return ERROR_OK;
 525 }
 526
 527 COMMAND_HANDLER(linuxgpiod_handle_gpiochip)
 528 {
 529         if (CMD_ARGC == 1)
 530                 COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], gpiochip);
 531
 532         command_print(CMD, "LinuxGPIOD gpiochip = %d", gpiochip);
 533         return ERROR_OK;
 534 }
 535
 536 static const struct command_registration linuxgpiod_subcommand_handlers[] = {
 537         {
 538                 .name = "jtag_nums",
 539                 .handler = linuxgpiod_handle_jtag_gpionums,
 540                 .mode = COMMAND_CONFIG,
 541                 .help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
 542                 .usage = "tck tms tdi tdo",
 543         },
 544         {
 545                 .name = "tck_num",
 546                 .handler = linuxgpiod_handle_jtag_gpionum_tck,
 547                 .mode = COMMAND_CONFIG,
 548                 .help = "gpio number for tck.",
 549                 .usage = "tck",
 550         },
 551         {
 552                 .name = "tms_num",
 553                 .handler = linuxgpiod_handle_jtag_gpionum_tms,
 554                 .mode = COMMAND_CONFIG,
 555                 .help = "gpio number for tms.",
 556                 .usage = "tms",
 557         },
 558         {
 559                 .name = "tdo_num",
 560                 .handler = linuxgpiod_handle_jtag_gpionum_tdo,
 561                 .mode = COMMAND_CONFIG,
 562                 .help = "gpio number for tdo.",
 563                 .usage = "tdo",
 564         },
 565         {
 566                 .name = "tdi_num",
 567                 .handler = linuxgpiod_handle_jtag_gpionum_tdi,
 568                 .mode = COMMAND_CONFIG,
 569                 .help = "gpio number for tdi.",
 570                 .usage = "tdi",
 571         },
 572         {
 573                 .name = "srst_num",
 574                 .handler = linuxgpiod_handle_jtag_gpionum_srst,
 575                 .mode = COMMAND_CONFIG,
 576                 .help = "gpio number for srst.",
 577                 .usage = "srst",
 578         },
 579         {
 580                 .name = "trst_num",
 581                 .handler = linuxgpiod_handle_jtag_gpionum_trst,
 582                 .mode = COMMAND_CONFIG,
 583                 .help = "gpio number for trst.",
 584                 .usage = "trst",
 585         },
 586         {
 587                 .name = "swd_nums",
 588                 .handler = linuxgpiod_handle_swd_gpionums,
 589                 .mode = COMMAND_CONFIG,
 590                 .help = "gpio numbers for swclk, swdio. (in that order)",
 591                 .usage = "swclk swdio",
 592         },
 593         {
 594                 .name = "swclk_num",
 595                 .handler = linuxgpiod_handle_swd_gpionum_swclk,
 596                 .mode = COMMAND_CONFIG,
 597                 .help = "gpio number for swclk.",
 598                 .usage = "swclk",
 599         },
 600         {
 601                 .name = "swdio_num",
 602                 .handler = linuxgpiod_handle_swd_gpionum_swdio,
 603                 .mode = COMMAND_CONFIG,
 604                 .help = "gpio number for swdio.",
 605                 .usage = "swdio",
 606         },
 607         {
 608                 .name = "led_num",
 609                 .handler = linuxgpiod_handle_gpionum_led,
 610                 .mode = COMMAND_CONFIG,
 611                 .help = "gpio number for LED.",
 612                 .usage = "led",
 613         },
 614         {
 615                 .name = "gpiochip",
 616                 .handler = linuxgpiod_handle_gpiochip,
 617                 .mode = COMMAND_CONFIG,
 618                 .help = "number of the gpiochip.",
 619                 .usage = "gpiochip",
 620         },
 621         COMMAND_REGISTRATION_DONE
 622 };
 623
 624 static const struct command_registration linuxgpiod_command_handlers[] = {
 625         {
 626                 .name = "linuxgpiod",
 627                 .mode = COMMAND_ANY,
 628                 .help = "perform linuxgpiod management",
 629                 .chain = linuxgpiod_subcommand_handlers,
 630                 .usage = "",
 631         },
 632         COMMAND_REGISTRATION_DONE
 633 };
 634
 635 static const char *const linuxgpiod_transport[] = { "swd", "jtag", NULL };
 636
 637 static struct jtag_interface linuxgpiod_interface = {
 638         .supported = DEBUG_CAP_TMS_SEQ,
 639         .execute_queue = bitbang_execute_queue,
 640 };
 641
 642 struct adapter_driver linuxgpiod_adapter_driver = {
 643         .name = "linuxgpiod",
 644         .transports = linuxgpiod_transport,
 645         .commands = linuxgpiod_command_handlers,
 646
 647         .init = linuxgpiod_init,
 648         .quit = linuxgpiod_quit,
 649         .reset = linuxgpiod_reset,
 650
 651         .jtag_ops = &linuxgpiod_interface,
 652         .swd_ops = &bitbang_swd,
 653 };