src/jtag/bitbang.c

   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  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  22  ***************************************************************************/
  23 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include "bitbang.h"
  28
  29 /* project specific includes */
  30 #include "log.h"
  31 #include "types.h"
  32 #include "jtag.h"
  33 #include "configuration.h"
  34
  35 /* system includes */
  36 #include <string.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39
  40
  41 /**
  42  * Function bitbang_stableclocks
  43  * issues a number of clock cycles while staying in a stable state.
  44  * Because the TMS value required to stay in the RESET state is a 1, whereas
  45  * the TMS value required to stay in any of the other stable states is a 0,
  46  * this function checks the current stable state to decide on the value of TMS
  47  * to use.
  48  */
  49 static void bitbang_stableclocks(int num_cycles);
  50
  51
  52 bitbang_interface_t *bitbang_interface;
  53
  54 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  55  *
  56  * Set this to 1 and str912 reset halt will fail.
  57  *
  58  * If someone can submit a patch with an explanation it will be greatly
  59  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  60  * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
  61  * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
  62  * state". With hardware there is no such thing as *while* in a state. There
  63  * are only edges. So clk => 0 is in fact a very subtle state transition that
  64  * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
  65  *
  66  * For "reset halt" the last thing that happens before srst is asserted
  67  * is that the breakpoint is set up. If DCLK is not wiggled one last
  68  * time before the reset, then the breakpoint is not set up and
  69  * "reset halt" will fail to halt.
  70  *
  71  */
  72 #define CLOCK_IDLE() 0
  73
  74 int bitbang_execute_queue(void);
  75
  76
  77
  78 /* The bitbang driver leaves the TCK 0 when in idle */
  79
  80 void bitbang_end_state(enum tap_state state)
  81 {
  82         if (tap_move_map[state] != -1)
  83                 end_state = state;
  84         else
  85         {
  86                 LOG_ERROR("BUG: %i is not a valid end state", state);
  87                 exit(-1);
  88         }
  89 }
  90
  91 void bitbang_state_move(void) {
  92
  93         int i=0, tms=0;
  94         u8 tms_scan = TAP_MOVE(cur_state, end_state);
  95
  96         for (i = 0; i < 7; i++)
  97         {
  98                 tms = (tms_scan >> i) & 1;
  99                 bitbang_interface->write(0, tms, 0);
 100                 bitbang_interface->write(1, tms, 0);
 101         }
 102         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 103
 104         cur_state = end_state;
 105 }
 106
 107 void bitbang_path_move(pathmove_command_t *cmd)
 108 {
 109         int num_states = cmd->num_states;
 110         int state_count;
 111         int tms = 0;
 112
 113         state_count = 0;
 114         while (num_states)
 115         {
 116                 if (tap_transitions[cur_state].low == cmd->path[state_count])
 117                 {
 118                         tms = 0;
 119                 }
 120                 else if (tap_transitions[cur_state].high == cmd->path[state_count])
 121                 {
 122                         tms = 1;
 123                 }
 124                 else
 125                 {
 126                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", jtag_state_name(cur_state), jtag_state_name(cmd->path[state_count]));
 127                         exit(-1);
 128                 }
 129
 130                 bitbang_interface->write(0, tms, 0);
 131                 bitbang_interface->write(1, tms, 0);
 132
 133                 cur_state = cmd->path[state_count];
 134                 state_count++;
 135                 num_states--;
 136         }
 137
 138         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 139
 140         end_state = cur_state;
 141 }
 142
 143 void bitbang_runtest(int num_cycles)
 144 {
 145         int i;
 146
 147         enum tap_state saved_end_state = end_state;
 148
 149         /* only do a state_move when we're not already in IDLE */
 150         if (cur_state != TAP_IDLE)
 151         {
 152                 bitbang_end_state(TAP_IDLE);
 153                 bitbang_state_move();
 154         }
 155
 156         /* execute num_cycles */
 157         for (i = 0; i < num_cycles; i++)
 158         {
 159                 bitbang_interface->write(0, 0, 0);
 160                 bitbang_interface->write(1, 0, 0);
 161         }
 162         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 163
 164         /* finish in end_state */
 165         bitbang_end_state(saved_end_state);
 166         if (cur_state != end_state)
 167                 bitbang_state_move();
 168 }
 169
 170
 171 static void bitbang_stableclocks(int num_cycles)
 172 {
 173         int tms = (cur_state == TAP_RESET ? 1 : 0);
 174         int i;
 175
 176         /* send num_cycles clocks onto the cable */
 177         for (i = 0; i < num_cycles; i++)
 178         {
 179                 bitbang_interface->write(1, tms, 0);
 180                 bitbang_interface->write(0, tms, 0);
 181         }
 182 }
 183
 184
 185
 186 void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 187 {
 188         enum tap_state saved_end_state = end_state;
 189         int bit_cnt;
 190
 191         if (!((!ir_scan && (cur_state == TAP_DRSHIFT)) || (ir_scan && (cur_state == TAP_IRSHIFT))))
 192         {
 193                 if (ir_scan)
 194                         bitbang_end_state(TAP_IRSHIFT);
 195                 else
 196                         bitbang_end_state(TAP_DRSHIFT);
 197
 198                 bitbang_state_move();
 199                 bitbang_end_state(saved_end_state);
 200         }
 201
 202         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 203         {
 204                 int val=0;
 205                 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
 206                 int tdi;
 207                 int bytec=bit_cnt/8;
 208                 int bcval=1<<(bit_cnt % 8);
 209
 210                 /* if we're just reading the scan, but don't care about the output
 211                  * default to outputting 'low', this also makes valgrind traces more readable,
 212                  * as it removes the dependency on an uninitialised value
 213                  */
 214                 tdi=0;
 215                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 216                         tdi=1;
 217
 218                 bitbang_interface->write(0, tms, tdi);
 219
 220                 if (type!=SCAN_OUT)
 221                         val=bitbang_interface->read();
 222
 223                 bitbang_interface->write(1, tms, tdi);
 224
 225                 if (type != SCAN_OUT)
 226                 {
 227                         if (val)
 228                                 buffer[bytec] |= bcval;
 229                         else
 230                                 buffer[bytec] &= ~bcval;
 231                 }
 232         }
 233
 234         /* TAP_DRSHIFT & TAP_IRSHIFT are illegal end states, so we always transition to the pause
 235          * state which is a legal stable state from which statemove will work.
 236          *
 237          * Exit1 -> Pause
 238          */
 239         bitbang_interface->write(0, 0, 0);
 240         bitbang_interface->write(1, 0, 0);
 241         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 242
 243         if (ir_scan)
 244                 cur_state = TAP_IRPAUSE;
 245         else
 246                 cur_state = TAP_DRPAUSE;
 247
 248         if (cur_state != end_state)
 249                 bitbang_state_move();
 250 }
 251
 252 int bitbang_execute_queue(void)
 253 {
 254         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 255         int scan_size;
 256         enum scan_type type;
 257         u8 *buffer;
 258         int retval;
 259
 260         if (!bitbang_interface)
 261         {
 262                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 263                 exit(-1);
 264         }
 265
 266         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 267          * that wasn't handled by a caller-provided error handler
 268          */
 269         retval = ERROR_OK;
 270
 271         if(bitbang_interface->blink)
 272                 bitbang_interface->blink(1);
 273
 274         while (cmd)
 275         {
 276                 switch (cmd->type)
 277                 {
 278                         case JTAG_END_STATE:
 279 #ifdef _DEBUG_JTAG_IO_
 280                                 LOG_DEBUG("end_state: %s", jtag_state_name(cmd->cmd.end_state->end_state) );
 281 #endif
 282                                 if (cmd->cmd.end_state->end_state != -1)
 283                                         bitbang_end_state(cmd->cmd.end_state->end_state);
 284                                 break;
 285                         case JTAG_RESET:
 286 #ifdef _DEBUG_JTAG_IO_
 287                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 288 #endif
 289                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 290                                 {
 291                                         cur_state = TAP_RESET;
 292                                 }
 293                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 294                                 break;
 295                         case JTAG_RUNTEST:
 296 #ifdef _DEBUG_JTAG_IO_
 297                                 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, jtag_state_name(cmd->cmd.runtest->end_state) );
 298 #endif
 299                                 if (cmd->cmd.runtest->end_state != -1)
 300                                         bitbang_end_state(cmd->cmd.runtest->end_state);
 301                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 302                                 break;
 303
 304                         case JTAG_STABLECLOCKS:
 305                                 /* this is only allowed while in a stable state.  A check for a stable
 306                                  * state was done in jtag_add_clocks()
 307                                  */
 308                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 309                                 break;
 310
 311                         case JTAG_STATEMOVE:
 312 #ifdef _DEBUG_JTAG_IO_
 313                                 LOG_DEBUG("statemove end in %s", jtag_state_name(cmd->cmd.statemove->end_state));
 314 #endif
 315                                 if (cmd->cmd.statemove->end_state != -1)
 316                                         bitbang_end_state(cmd->cmd.statemove->end_state);
 317                                 bitbang_state_move();
 318                                 break;
 319                         case JTAG_PATHMOVE:
 320 #ifdef _DEBUG_JTAG_IO_
 321                                 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
 322                                         jtag_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 323 #endif
 324                                 bitbang_path_move(cmd->cmd.pathmove);
 325                                 break;
 326                         case JTAG_SCAN:
 327 #ifdef _DEBUG_JTAG_IO_
 328                                 LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", jtag_state_name(cmd->cmd.scan->end_state) );
 329 #endif
 330                                 if (cmd->cmd.scan->end_state != -1)
 331                                         bitbang_end_state(cmd->cmd.scan->end_state);
 332                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 333                                 type = jtag_scan_type(cmd->cmd.scan);
 334                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 335                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 336                                         retval = ERROR_JTAG_QUEUE_FAILED;
 337                                 if (buffer)
 338                                         free(buffer);
 339                                 break;
 340                         case JTAG_SLEEP:
 341 #ifdef _DEBUG_JTAG_IO_
 342                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 343 #endif
 344                                 jtag_sleep(cmd->cmd.sleep->us);
 345                                 break;
 346                         default:
 347                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 348                                 exit(-1);
 349                 }
 350                 cmd = cmd->next;
 351         }
 352         if(bitbang_interface->blink)
 353                 bitbang_interface->blink(0);
 354
 355         return retval;
 356 }