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