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