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   1 /***************************************************************************
   2  *   Copyright (C) 2005 by Dominic Rath                                    *
   3  *   Dominic.Rath@gmx.de                                                   *
   4  *                                                                         *
   5  *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
   6  *   oyvind.harboe@zylin.com                                               *
   7  *                                                                         *
   8  *   This program is free software; you can redistribute it and/or modify  *
   9  *   it under the terms of the GNU General Public License as published by  *
  10  *   the Free Software Foundation; either version 2 of the License, or     *
  11  *   (at your option) any later version.                                   *
  12  *                                                                         *
  13  *   This program is distributed in the hope that it will be useful,       *
  14  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  15  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  16  *   GNU General Public License for more details.                          *
  17  *                                                                         *
  18  *   You should have received a copy of the GNU General Public License     *
  19  *   along with this program; if not, write to the                         *
  20  *   Free Software Foundation, Inc.,                                       *
  21  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
  22  ***************************************************************************/
  23
  24 /* 2014-12: Addition of the SWD protocol support is based on the initial work
  25  * by Paul Fertser and modifications by Jean-Christian de Rivaz. */
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include "bitbang.h"
  32 #include <jtag/interface.h>
  33 #include <jtag/commands.h>
  34
  35 /* YUK! - but this is currently a global.... */
  36 extern struct jtag_interface *jtag_interface;
  37
  38 /**
  39  * Function bitbang_stableclocks
  40  * issues a number of clock cycles while staying in a stable state.
  41  * Because the TMS value required to stay in the RESET state is a 1, whereas
  42  * the TMS value required to stay in any of the other stable states is a 0,
  43  * this function checks the current stable state to decide on the value of TMS
  44  * to use.
  45  */
  46 static void bitbang_stableclocks(int num_cycles);
  47
  48 static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk);
  49
  50 struct bitbang_interface *bitbang_interface;
  51
  52 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  53  *
  54  * Set this to 1 and str912 reset halt will fail.
  55  *
  56  * If someone can submit a patch with an explanation it will be greatly
  57  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  58  * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
  59  * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
  60  * state". With hardware there is no such thing as *while* in a state. There
  61  * are only edges. So clk => 0 is in fact a very subtle state transition that
  62  * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
  63  *
  64  * For "reset halt" the last thing that happens before srst is asserted
  65  * is that the breakpoint is set up. If DCLK is not wiggled one last
  66  * time before the reset, then the breakpoint is not set up and
  67  * "reset halt" will fail to halt.
  68  *
  69  */
  70 #define CLOCK_IDLE() 0
  71
  72 /* The bitbang driver leaves the TCK 0 when in idle */
  73 static void bitbang_end_state(tap_state_t state)
  74 {
  75         if (tap_is_state_stable(state))
  76                 tap_set_end_state(state);
  77         else {
  78                 LOG_ERROR("BUG: %i is not a valid end state", state);
  79                 exit(-1);
  80         }
  81 }
  82
  83 static void bitbang_state_move(int skip)
  84 {
  85         int i = 0, tms = 0;
  86         uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
  87         int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
  88
  89         for (i = skip; i < tms_count; i++) {
  90                 tms = (tms_scan >> i) & 1;
  91                 bitbang_interface->write(0, tms, 0);
  92                 bitbang_interface->write(1, tms, 0);
  93         }
  94         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  95
  96         tap_set_state(tap_get_end_state());
  97 }
  98
  99 /**
 100  * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
 101  * (or SWD) state machine.
 102  */
 103 static int bitbang_execute_tms(struct jtag_command *cmd)
 104 {
 105         unsigned num_bits = cmd->cmd.tms->num_bits;
 106         const uint8_t *bits = cmd->cmd.tms->bits;
 107
 108         DEBUG_JTAG_IO("TMS: %d bits", num_bits);
 109
 110         int tms = 0;
 111         for (unsigned i = 0; i < num_bits; i++) {
 112                 tms = ((bits[i/8] >> (i % 8)) & 1);
 113                 bitbang_interface->write(0, tms, 0);
 114                 bitbang_interface->write(1, tms, 0);
 115         }
 116         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 117
 118         return ERROR_OK;
 119 }
 120
 121 static void bitbang_path_move(struct pathmove_command *cmd)
 122 {
 123         int num_states = cmd->num_states;
 124         int state_count;
 125         int tms = 0;
 126
 127         state_count = 0;
 128         while (num_states) {
 129                 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
 130                         tms = 0;
 131                 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
 132                         tms = 1;
 133                 else {
 134                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
 135                                 tap_state_name(tap_get_state()),
 136                                 tap_state_name(cmd->path[state_count]));
 137                         exit(-1);
 138                 }
 139
 140                 bitbang_interface->write(0, tms, 0);
 141                 bitbang_interface->write(1, tms, 0);
 142
 143                 tap_set_state(cmd->path[state_count]);
 144                 state_count++;
 145                 num_states--;
 146         }
 147
 148         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 149
 150         tap_set_end_state(tap_get_state());
 151 }
 152
 153 static void bitbang_runtest(int num_cycles)
 154 {
 155         int i;
 156
 157         tap_state_t saved_end_state = tap_get_end_state();
 158
 159         /* only do a state_move when we're not already in IDLE */
 160         if (tap_get_state() != TAP_IDLE) {
 161                 bitbang_end_state(TAP_IDLE);
 162                 bitbang_state_move(0);
 163         }
 164
 165         /* execute num_cycles */
 166         for (i = 0; i < num_cycles; i++) {
 167                 bitbang_interface->write(0, 0, 0);
 168                 bitbang_interface->write(1, 0, 0);
 169         }
 170         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 171
 172         /* finish in end_state */
 173         bitbang_end_state(saved_end_state);
 174         if (tap_get_state() != tap_get_end_state())
 175                 bitbang_state_move(0);
 176 }
 177
 178 static void bitbang_stableclocks(int num_cycles)
 179 {
 180         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 181         int i;
 182
 183         /* send num_cycles clocks onto the cable */
 184         for (i = 0; i < num_cycles; i++) {
 185                 bitbang_interface->write(1, tms, 0);
 186                 bitbang_interface->write(0, tms, 0);
 187         }
 188 }
 189
 190 static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size)
 191 {
 192         tap_state_t saved_end_state = tap_get_end_state();
 193         int bit_cnt;
 194
 195         if (!((!ir_scan &&
 196                         (tap_get_state() == TAP_DRSHIFT)) ||
 197                         (ir_scan && (tap_get_state() == TAP_IRSHIFT)))) {
 198                 if (ir_scan)
 199                         bitbang_end_state(TAP_IRSHIFT);
 200                 else
 201                         bitbang_end_state(TAP_DRSHIFT);
 202
 203                 bitbang_state_move(0);
 204                 bitbang_end_state(saved_end_state);
 205         }
 206
 207         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++) {
 208                 int val = 0;
 209                 int tms = (bit_cnt == scan_size-1) ? 1 : 0;
 210                 int tdi;
 211                 int bytec = bit_cnt/8;
 212                 int bcval = 1 << (bit_cnt % 8);
 213
 214                 /* if we're just reading the scan, but don't care about the output
 215                  * default to outputting 'low', this also makes valgrind traces more readable,
 216                  * as it removes the dependency on an uninitialised value
 217                  */
 218                 tdi = 0;
 219                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 220                         tdi = 1;
 221
 222                 bitbang_interface->write(0, tms, tdi);
 223
 224                 if (type != SCAN_OUT)
 225                         val = bitbang_interface->read();
 226
 227                 bitbang_interface->write(1, tms, tdi);
 228
 229                 if (type != SCAN_OUT) {
 230                         if (val)
 231                                 buffer[bytec] |= bcval;
 232                         else
 233                                 buffer[bytec] &= ~bcval;
 234                 }
 235         }
 236
 237         if (tap_get_state() != tap_get_end_state()) {
 238                 /* we *KNOW* the above loop transitioned out of
 239                  * the shift state, so we skip the first state
 240                  * and move directly to the end state.
 241                  */
 242                 bitbang_state_move(1);
 243         }
 244 }
 245
 246 int bitbang_execute_queue(void)
 247 {
 248         struct jtag_command *cmd = jtag_command_queue;  /* currently processed command */
 249         int scan_size;
 250         enum scan_type type;
 251         uint8_t *buffer;
 252         int retval;
 253
 254         if (!bitbang_interface) {
 255                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 256                 exit(-1);
 257         }
 258
 259         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 260          * that wasn't handled by a caller-provided error handler
 261          */
 262         retval = ERROR_OK;
 263
 264         if (bitbang_interface->blink)
 265                 bitbang_interface->blink(1);
 266
 267         while (cmd) {
 268                 switch (cmd->type) {
 269                         case JTAG_RESET:
 270 #ifdef _DEBUG_JTAG_IO_
 271                                 LOG_DEBUG("reset trst: %i srst %i",
 272                                 cmd->cmd.reset->trst,
 273                                 cmd->cmd.reset->srst);
 274 #endif
 275                                 if ((cmd->cmd.reset->trst == 1) ||
 276                                                 (cmd->cmd.reset->srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
 277                                         tap_set_state(TAP_RESET);
 278                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 279                                 break;
 280                         case JTAG_RUNTEST:
 281 #ifdef _DEBUG_JTAG_IO_
 282                                 LOG_DEBUG("runtest %i cycles, end in %s",
 283                                                 cmd->cmd.runtest->num_cycles,
 284                                                 tap_state_name(cmd->cmd.runtest->end_state));
 285 #endif
 286                                 bitbang_end_state(cmd->cmd.runtest->end_state);
 287                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 288                                 break;
 289
 290                         case JTAG_STABLECLOCKS:
 291                                 /* this is only allowed while in a stable state.  A check for a stable
 292                                  * state was done in jtag_add_clocks()
 293                                  */
 294                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 295                                 break;
 296
 297                         case JTAG_TLR_RESET:
 298 #ifdef _DEBUG_JTAG_IO_
 299                                 LOG_DEBUG("statemove end in %s",
 300                                                 tap_state_name(cmd->cmd.statemove->end_state));
 301 #endif
 302                                 bitbang_end_state(cmd->cmd.statemove->end_state);
 303                                 bitbang_state_move(0);
 304                                 break;
 305                         case JTAG_PATHMOVE:
 306 #ifdef _DEBUG_JTAG_IO_
 307                                 LOG_DEBUG("pathmove: %i states, end in %s",
 308                                                 cmd->cmd.pathmove->num_states,
 309                                                 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 310 #endif
 311                                 bitbang_path_move(cmd->cmd.pathmove);
 312                                 break;
 313                         case JTAG_SCAN:
 314 #ifdef _DEBUG_JTAG_IO_
 315                                 LOG_DEBUG("%s scan end in %s",
 316                                                 (cmd->cmd.scan->ir_scan) ? "IR" : "DR",
 317                                         tap_state_name(cmd->cmd.scan->end_state));
 318 #endif
 319                                 bitbang_end_state(cmd->cmd.scan->end_state);
 320                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 321                                 type = jtag_scan_type(cmd->cmd.scan);
 322                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 323                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 324                                         retval = ERROR_JTAG_QUEUE_FAILED;
 325                                 if (buffer)
 326                                         free(buffer);
 327                                 break;
 328                         case JTAG_SLEEP:
 329 #ifdef _DEBUG_JTAG_IO_
 330                                 LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us);
 331 #endif
 332                                 jtag_sleep(cmd->cmd.sleep->us);
 333                                 break;
 334                         case JTAG_TMS:
 335                                 retval = bitbang_execute_tms(cmd);
 336                                 break;
 337                         default:
 338                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 339                                 exit(-1);
 340                 }
 341                 cmd = cmd->next;
 342         }
 343         if (bitbang_interface->blink)
 344                 bitbang_interface->blink(0);
 345
 346         return retval;
 347 }
 348
 349
 350 bool swd_mode;
 351 static int queued_retval;
 352
 353 static int bitbang_swd_init(void)
 354 {
 355         LOG_DEBUG("bitbang_swd_init");
 356         swd_mode = true;
 357         return ERROR_OK;
 358 }
 359
 360 static void bitbang_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsigned int bit_cnt)
 361 {
 362         LOG_DEBUG("bitbang_exchange");
 363         int tdi;
 364
 365         for (unsigned int i = offset; i < bit_cnt + offset; i++) {
 366                 int bytec = i/8;
 367                 int bcval = 1 << (i % 8);
 368                 tdi = !rnw && (buf[bytec] & bcval);
 369
 370                 bitbang_interface->write(0, 0, tdi);
 371
 372                 if (rnw && buf) {
 373                         if (bitbang_interface->swdio_read())
 374                                 buf[bytec] |= bcval;
 375                         else
 376                                 buf[bytec] &= ~bcval;
 377                 }
 378
 379                 bitbang_interface->write(1, 0, tdi);
 380         }
 381 }
 382
 383 int bitbang_swd_switch_seq(enum swd_special_seq seq)
 384 {
 385         LOG_DEBUG("bitbang_swd_switch_seq");
 386
 387         switch (seq) {
 388         case LINE_RESET:
 389                 LOG_DEBUG("SWD line reset");
 390                 bitbang_exchange(false, (uint8_t *)swd_seq_line_reset, 0, swd_seq_line_reset_len);
 391                 break;
 392         case JTAG_TO_SWD:
 393                 LOG_DEBUG("JTAG-to-SWD");
 394                 bitbang_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
 395                 break;
 396         case SWD_TO_JTAG:
 397                 LOG_DEBUG("SWD-to-JTAG");
 398                 bitbang_exchange(false, (uint8_t *)swd_seq_swd_to_jtag, 0, swd_seq_swd_to_jtag_len);
 399                 break;
 400         default:
 401                 LOG_ERROR("Sequence %d not supported", seq);
 402                 return ERROR_FAIL;
 403         }
 404
 405         return ERROR_OK;
 406 }
 407
 408 void bitbang_switch_to_swd(void)
 409 {
 410         LOG_DEBUG("bitbang_switch_to_swd");
 411         bitbang_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
 412 }
 413
 414 static void swd_clear_sticky_errors(void)
 415 {
 416         bitbang_swd_write_reg(swd_cmd(false,  false, DP_ABORT),
 417                 STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
 418 }
 419
 420 static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
 421 {
 422         LOG_DEBUG("bitbang_swd_read_reg");
 423         assert(cmd & SWD_CMD_RnW);
 424
 425         if (queued_retval != ERROR_OK) {
 426                 LOG_DEBUG("Skip bitbang_swd_read_reg because queued_retval=%d", queued_retval);
 427                 return;
 428         }
 429
 430         for (;;) {
 431                 uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
 432
 433                 cmd |= SWD_CMD_START | (1 << 7);
 434                 bitbang_exchange(false, &cmd, 0, 8);
 435
 436                 bitbang_interface->swdio_drive(false);
 437                 bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 32 + 1 + 1);
 438                 bitbang_interface->swdio_drive(true);
 439
 440                 int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
 441                 uint32_t data = buf_get_u32(trn_ack_data_parity_trn, 1 + 3, 32);
 442                 int parity = buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 32, 1);
 443
 444                 LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
 445                           ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
 446                           cmd & SWD_CMD_APnDP ? "AP" : "DP",
 447                           cmd & SWD_CMD_RnW ? "read" : "write",
 448                           (cmd & SWD_CMD_A32) >> 1,
 449                           data);
 450
 451                 switch (ack) {
 452                  case SWD_ACK_OK:
 453                         if (parity != parity_u32(data)) {
 454                                 LOG_DEBUG("Wrong parity detected");
 455                                 queued_retval = ERROR_FAIL;
 456                                 return;
 457                         }
 458                         if (value)
 459                                 *value = data;
 460                         if (cmd & SWD_CMD_APnDP)
 461                                 bitbang_exchange(true, NULL, 0, ap_delay_clk);
 462                         return;
 463                  case SWD_ACK_WAIT:
 464                         LOG_DEBUG("SWD_ACK_WAIT");
 465                         swd_clear_sticky_errors();
 466                         break;
 467                  case SWD_ACK_FAULT:
 468                         LOG_DEBUG("SWD_ACK_FAULT");
 469                         queued_retval = ack;
 470                         return;
 471                  default:
 472                         LOG_DEBUG("No valid acknowledge: ack=%d", ack);
 473                         queued_retval = ack;
 474                         return;
 475                 }
 476         }
 477 }
 478
 479 static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
 480 {
 481         LOG_DEBUG("bitbang_swd_write_reg");
 482         assert(!(cmd & SWD_CMD_RnW));
 483
 484         if (queued_retval != ERROR_OK) {
 485                 LOG_DEBUG("Skip bitbang_swd_write_reg because queued_retval=%d", queued_retval);
 486                 return;
 487         }
 488
 489         for (;;) {
 490                 uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
 491                 buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32, value);
 492                 buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1 + 32, 1, parity_u32(value));
 493
 494                 cmd |= SWD_CMD_START | (1 << 7);
 495                 bitbang_exchange(false, &cmd, 0, 8);
 496
 497                 bitbang_interface->swdio_drive(false);
 498                 bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 1);
 499                 bitbang_interface->swdio_drive(true);
 500                 bitbang_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);
 501
 502                 int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
 503                 LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
 504                           ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
 505                           cmd & SWD_CMD_APnDP ? "AP" : "DP",
 506                           cmd & SWD_CMD_RnW ? "read" : "write",
 507                           (cmd & SWD_CMD_A32) >> 1,
 508                           buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32));
 509
 510                 switch (ack) {
 511                  case SWD_ACK_OK:
 512                         if (cmd & SWD_CMD_APnDP)
 513                                 bitbang_exchange(true, NULL, 0, ap_delay_clk);
 514                         return;
 515                  case SWD_ACK_WAIT:
 516                         LOG_DEBUG("SWD_ACK_WAIT");
 517                         swd_clear_sticky_errors();
 518                         break;
 519                  case SWD_ACK_FAULT:
 520                         LOG_DEBUG("SWD_ACK_FAULT");
 521                         queued_retval = ack;
 522                         return;
 523                  default:
 524                         LOG_DEBUG("No valid acknowledge: ack=%d", ack);
 525                         queued_retval = ack;
 526                         return;
 527                 }
 528         }
 529 }
 530
 531 static int bitbang_swd_run_queue(void)
 532 {
 533         LOG_DEBUG("bitbang_swd_run_queue");
 534         /* A transaction must be followed by another transaction or at least 8 idle cycles to
 535          * ensure that data is clocked through the AP. */
 536         bitbang_exchange(true, NULL, 0, 8);
 537
 538         int retval = queued_retval;
 539         queued_retval = ERROR_OK;
 540         LOG_DEBUG("SWD queue return value: %02x", retval);
 541         return retval;
 542 }
 543
 544 const struct swd_driver bitbang_swd = {
 545         .init = bitbang_swd_init,
 546         .switch_seq = bitbang_swd_switch_seq,
 547         .read_reg = bitbang_swd_read_reg,
 548         .write_reg = bitbang_swd_write_reg,
 549         .run = bitbang_swd_run_queue,
 550 };