src/jtag/bitbang.c

   1 /***************************************************************************
   2  *   Copyright (C) 2005 by Dominic Rath                                    *
   3  *   Dominic.Rath@gmx.de                                                   *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include "bitbang.h"
  25
  26 /* project specific includes */
  27 #include "log.h"
  28 #include "types.h"
  29 #include "jtag.h"
  30 #include "configuration.h"
  31
  32 /* system includes */
  33 #include <string.h>
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36
  37 bitbang_interface_t *bitbang_interface;
  38
  39
  40 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  41  *
  42  * Set this to 1 and str912 reset halt will fail.
  43  *
  44  * If someone can submit a patch with an explanation it will be greatly
  45  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  46  * clk=0 in TAP_RTI. Good luck deducing that from the ARM documentation!
  47  * The ARM documentation uses the term "DCLK is asserted while in the TAP_RTI
  48  * state". With hardware there is no such thing as *while* in a state. There
  49  * are only edges. So clk => 0 is in fact a very subtle state transition that
  50  * happens *while* in the TAP_RTI state. "#&¤"#¤&"#&"#&
  51  *
  52  * For "reset halt" the last thing that happens before srst is asserted
  53  * is that the breakpoint is set up. If DCLK is not wiggled one last
  54  * time before the reset, then the breakpoint is not set up and
  55  * "reset halt" will fail to halt.
  56  *
  57  */
  58 #define CLOCK_IDLE() 0
  59
  60 int bitbang_execute_queue(void);
  61
  62 /* The bitbang driver leaves the TCK 0 when in idle */
  63
  64 void bitbang_end_state(enum tap_state state)
  65 {
  66         if (tap_move_map[state] != -1)
  67                 end_state = state;
  68         else
  69         {
  70                 LOG_ERROR("BUG: %i is not a valid end state", state);
  71                 exit(-1);
  72         }
  73 }
  74
  75 void bitbang_state_move(void) {
  76
  77         int i=0, tms=0;
  78         u8 tms_scan = TAP_MOVE(cur_state, end_state);
  79
  80         for (i = 0; i < 7; i++)
  81         {
  82                 tms = (tms_scan >> i) & 1;
  83                 bitbang_interface->write(0, tms, 0);
  84                 bitbang_interface->write(1, tms, 0);
  85         }
  86         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  87
  88         cur_state = end_state;
  89 }
  90
  91 void bitbang_path_move(pathmove_command_t *cmd)
  92 {
  93         int num_states = cmd->num_states;
  94         int state_count;
  95         int tms = 0;
  96
  97         state_count = 0;
  98         while (num_states)
  99         {
 100                 if (tap_transitions[cur_state].low == cmd->path[state_count])
 101                 {
 102                         tms = 0;
 103                 }
 104                 else if (tap_transitions[cur_state].high == cmd->path[state_count])
 105                 {
 106                         tms = 1;
 107                 }
 108                 else
 109                 {
 110                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_strings[cur_state], tap_state_strings[cmd->path[state_count]]);
 111                         exit(-1);
 112                 }
 113
 114                 bitbang_interface->write(0, tms, 0);
 115                 bitbang_interface->write(1, tms, 0);
 116
 117                 cur_state = cmd->path[state_count];
 118                 state_count++;
 119                 num_states--;
 120         }
 121
 122         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 123
 124         end_state = cur_state;
 125 }
 126
 127 void bitbang_runtest(int num_cycles)
 128 {
 129         int i;
 130
 131         enum tap_state saved_end_state = end_state;
 132
 133         /* only do a state_move when we're not already in RTI */
 134         if (cur_state != TAP_RTI)
 135         {
 136                 bitbang_end_state(TAP_RTI);
 137                 bitbang_state_move();
 138         }
 139
 140         /* execute num_cycles */
 141         for (i = 0; i < num_cycles; i++)
 142         {
 143                 bitbang_interface->write(0, 0, 0);
 144                 bitbang_interface->write(1, 0, 0);
 145         }
 146         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 147
 148         /* finish in end_state */
 149         bitbang_end_state(saved_end_state);
 150         if (cur_state != end_state)
 151                 bitbang_state_move();
 152 }
 153
 154 void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 155 {
 156         enum tap_state saved_end_state = end_state;
 157         int bit_cnt;
 158
 159         if (!((!ir_scan && (cur_state == TAP_SD)) || (ir_scan && (cur_state == TAP_SI))))
 160         {
 161                 if (ir_scan)
 162                         bitbang_end_state(TAP_SI);
 163                 else
 164                         bitbang_end_state(TAP_SD);
 165
 166                 bitbang_state_move();
 167                 bitbang_end_state(saved_end_state);
 168         }
 169
 170         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 171         {
 172                 /* if we're just reading the scan, but don't care about the output
 173                  * default to outputting 'low', this also makes valgrind traces more readable,
 174                  * as it removes the dependency on an uninitialised value
 175                  */
 176                 if ((type != SCAN_IN) && ((buffer[bit_cnt/8] >> (bit_cnt % 8)) & 0x1))
 177                 {
 178                         bitbang_interface->write(0, (bit_cnt==scan_size-1) ? 1 : 0, 1);
 179                         bitbang_interface->write(1, (bit_cnt==scan_size-1) ? 1 : 0, 1);
 180                 } else {
 181                         bitbang_interface->write(0, (bit_cnt==scan_size-1) ? 1 : 0, 0);
 182                         bitbang_interface->write(1, (bit_cnt==scan_size-1) ? 1 : 0, 0);
 183                 }
 184
 185                 if (type != SCAN_OUT)
 186                 {
 187                         /*
 188                         TDO should be sampled on the rising edge, and will change
 189                         on the falling edge.
 190
 191                         Because there is no way to read the signal exactly at the rising edge,
 192                         read after the rising edge.
 193
 194                         This is plain IEEE 1149 JTAG - nothing specific to the OpenOCD or its JTAG
 195                         API.
 196                         */
 197                         if (bitbang_interface->read())
 198                                 buffer[(bit_cnt)/8] |= 1 << ((bit_cnt) % 8);
 199                         else
 200                                 buffer[(bit_cnt)/8] &= ~(1 << ((bit_cnt) % 8));
 201                 }
 202         }
 203
 204         /* TAP_SD & TAP_SI are illegal end states, so we always transition to the pause
 205          * state which is a legal stable state from which statemove will work.
 206          *
 207          * Exit1 -> Pause
 208          */
 209         bitbang_interface->write(0, 0, 0);
 210         bitbang_interface->write(1, 0, 0);
 211         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 212
 213         if (ir_scan)
 214                 cur_state = TAP_PI;
 215         else
 216                 cur_state = TAP_PD;
 217
 218         if (cur_state != end_state)
 219                 bitbang_state_move();
 220 }
 221
 222 int bitbang_execute_queue(void)
 223 {
 224         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 225         int scan_size;
 226         enum scan_type type;
 227         u8 *buffer;
 228         int retval;
 229
 230         if (!bitbang_interface)
 231         {
 232                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 233                 exit(-1);
 234         }
 235
 236         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 237          * that wasn't handled by a caller-provided error handler
 238          */
 239         retval = ERROR_OK;
 240
 241         if(bitbang_interface->blink)
 242                 bitbang_interface->blink(1);
 243
 244         while (cmd)
 245         {
 246                 switch (cmd->type)
 247                 {
 248                         case JTAG_END_STATE:
 249 #ifdef _DEBUG_JTAG_IO_
 250                                 LOG_DEBUG("end_state: %i", cmd->cmd.end_state->end_state);
 251 #endif
 252                                 if (cmd->cmd.end_state->end_state != -1)
 253                                         bitbang_end_state(cmd->cmd.end_state->end_state);
 254                                 break;
 255                         case JTAG_RESET:
 256 #ifdef _DEBUG_JTAG_IO_
 257                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 258 #endif
 259                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 260                                 {
 261                                         cur_state = TAP_TLR;
 262                                 }
 263                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 264                                 break;
 265                         case JTAG_RUNTEST:
 266 #ifdef _DEBUG_JTAG_IO_
 267                                 LOG_DEBUG("runtest %i cycles, end in %i", cmd->cmd.runtest->num_cycles, cmd->cmd.runtest->end_state);
 268 #endif
 269                                 if (cmd->cmd.runtest->end_state != -1)
 270                                         bitbang_end_state(cmd->cmd.runtest->end_state);
 271                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 272                                 break;
 273                         case JTAG_STATEMOVE:
 274 #ifdef _DEBUG_JTAG_IO_
 275                                 LOG_DEBUG("statemove end in %i", cmd->cmd.statemove->end_state);
 276 #endif
 277                                 if (cmd->cmd.statemove->end_state != -1)
 278                                         bitbang_end_state(cmd->cmd.statemove->end_state);
 279                                 bitbang_state_move();
 280                                 break;
 281                         case JTAG_PATHMOVE:
 282 #ifdef _DEBUG_JTAG_IO_
 283                                 LOG_DEBUG("pathmove: %i states, end in %i", cmd->cmd.pathmove->num_states, cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]);
 284 #endif
 285                                 bitbang_path_move(cmd->cmd.pathmove);
 286                                 break;
 287                         case JTAG_SCAN:
 288 #ifdef _DEBUG_JTAG_IO_
 289                                 LOG_DEBUG("%s scan end in %i",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", cmd->cmd.scan->end_state);
 290 #endif
 291                                 if (cmd->cmd.scan->end_state != -1)
 292                                         bitbang_end_state(cmd->cmd.scan->end_state);
 293                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 294                                 type = jtag_scan_type(cmd->cmd.scan);
 295                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 296                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 297                                         retval = ERROR_JTAG_QUEUE_FAILED;
 298                                 if (buffer)
 299                                         free(buffer);
 300                                 break;
 301                         case JTAG_SLEEP:
 302 #ifdef _DEBUG_JTAG_IO_
 303                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 304 #endif
 305                                 jtag_sleep(cmd->cmd.sleep->us);
 306                                 break;
 307                         default:
 308                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 309                                 exit(-1);
 310                 }
 311                 cmd = cmd->next;
 312         }
 313         if(bitbang_interface->blink)
 314                 bitbang_interface->blink(0);
 315
 316         return retval;
 317 }
 318