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 #include "interface.h"
  29 #include "commands.h"
  30
  31 /**
  32  * Function bitbang_stableclocks
  33  * issues a number of clock cycles while staying in a stable state.
  34  * Because the TMS value required to stay in the RESET state is a 1, whereas
  35  * the TMS value required to stay in any of the other stable states is a 0,
  36  * this function checks the current stable state to decide on the value of TMS
  37  * to use.
  38  */
  39 static void bitbang_stableclocks(int num_cycles);
  40
  41
  42 bitbang_interface_t *bitbang_interface;
  43
  44 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  45  *
  46  * Set this to 1 and str912 reset halt will fail.
  47  *
  48  * If someone can submit a patch with an explanation it will be greatly
  49  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  50  * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
  51  * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
  52  * state". With hardware there is no such thing as *while* in a state. There
  53  * are only edges. So clk => 0 is in fact a very subtle state transition that
  54  * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
  55  *
  56  * For "reset halt" the last thing that happens before srst is asserted
  57  * is that the breakpoint is set up. If DCLK is not wiggled one last
  58  * time before the reset, then the breakpoint is not set up and
  59  * "reset halt" will fail to halt.
  60  *
  61  */
  62 #define CLOCK_IDLE() 0
  63
  64
  65 /* The bitbang driver leaves the TCK 0 when in idle */
  66 static void bitbang_end_state(tap_state_t state)
  67 {
  68         if (tap_is_state_stable(state))
  69                 tap_set_end_state(state);
  70         else
  71         {
  72                 LOG_ERROR("BUG: %i is not a valid end state", state);
  73                 exit(-1);
  74         }
  75 }
  76
  77 static void bitbang_state_move(int skip)
  78 {
  79         int i = 0, tms = 0;
  80         uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
  81         int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
  82
  83         for (i = skip; i < tms_count; 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         tap_set_state(tap_get_end_state());
  92 }
  93
  94 static 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_state_transition(tap_get_state(), false) == cmd->path[state_count])
 104                 {
 105                         tms = 0;
 106                 }
 107                 else if (tap_state_transition(tap_get_state(), true) == 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_name(tap_get_state()), tap_state_name(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                 tap_set_state(cmd->path[state_count]);
 121                 state_count++;
 122                 num_states--;
 123         }
 124
 125         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 126
 127         tap_set_end_state(tap_get_state());
 128 }
 129
 130 static void bitbang_runtest(int num_cycles)
 131 {
 132         int i;
 133
 134         tap_state_t saved_end_state = tap_get_end_state();
 135
 136         /* only do a state_move when we're not already in IDLE */
 137         if (tap_get_state() != TAP_IDLE)
 138         {
 139                 bitbang_end_state(TAP_IDLE);
 140                 bitbang_state_move(0);
 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 (tap_get_state() != tap_get_end_state())
 154                 bitbang_state_move(0);
 155 }
 156
 157
 158 static void bitbang_stableclocks(int num_cycles)
 159 {
 160         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 161         int i;
 162
 163         /* send num_cycles clocks onto the cable */
 164         for (i = 0; i < num_cycles; i++)
 165         {
 166                 bitbang_interface->write(1, tms, 0);
 167                 bitbang_interface->write(0, tms, 0);
 168         }
 169 }
 170
 171
 172
 173 static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size)
 174 {
 175         tap_state_t saved_end_state = tap_get_end_state();
 176         int bit_cnt;
 177
 178         if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
 179         {
 180                 if (ir_scan)
 181                         bitbang_end_state(TAP_IRSHIFT);
 182                 else
 183                         bitbang_end_state(TAP_DRSHIFT);
 184
 185                 bitbang_state_move(0);
 186                 bitbang_end_state(saved_end_state);
 187         }
 188
 189         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 190         {
 191                 int val = 0;
 192                 int tms = (bit_cnt == scan_size-1) ? 1 : 0;
 193                 int tdi;
 194                 int bytec = bit_cnt/8;
 195                 int bcval = 1 << (bit_cnt % 8);
 196
 197                 /* if we're just reading the scan, but don't care about the output
 198                  * default to outputting 'low', this also makes valgrind traces more readable,
 199                  * as it removes the dependency on an uninitialised value
 200                  */
 201                 tdi = 0;
 202                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 203                         tdi = 1;
 204
 205                 bitbang_interface->write(0, tms, tdi);
 206
 207                 if (type != SCAN_OUT)
 208                         val = bitbang_interface->read();
 209
 210                 bitbang_interface->write(1, tms, tdi);
 211
 212                 if (type != SCAN_OUT)
 213                 {
 214                         if (val)
 215                                 buffer[bytec] |= bcval;
 216                         else
 217                                 buffer[bytec] &= ~bcval;
 218                 }
 219         }
 220
 221         if (tap_get_state() != tap_get_end_state())
 222         {
 223                 /* we *KNOW* the above loop transitioned out of
 224                  * the shift state, so we skip the first state
 225                  * and move directly to the end state.
 226                  */
 227                 bitbang_state_move(1);
 228         }
 229 }
 230
 231 int bitbang_execute_queue(void)
 232 {
 233         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 234         int scan_size;
 235         enum scan_type type;
 236         uint8_t *buffer;
 237         int retval;
 238
 239         if (!bitbang_interface)
 240         {
 241                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 242                 exit(-1);
 243         }
 244
 245         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 246          * that wasn't handled by a caller-provided error handler
 247          */
 248         retval = ERROR_OK;
 249
 250         if (bitbang_interface->blink)
 251                 bitbang_interface->blink(1);
 252
 253         while (cmd)
 254         {
 255                 switch (cmd->type)
 256                 {
 257                         case JTAG_RESET:
 258 #ifdef _DEBUG_JTAG_IO_
 259                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 260 #endif
 261                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
 262                                 {
 263                                         tap_set_state(TAP_RESET);
 264                                 }
 265                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 266                                 break;
 267                         case JTAG_RUNTEST:
 268 #ifdef _DEBUG_JTAG_IO_
 269                                 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state));
 270 #endif
 271                                 bitbang_end_state(cmd->cmd.runtest->end_state);
 272                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 273                                 break;
 274
 275                         case JTAG_STABLECLOCKS:
 276                                 /* this is only allowed while in a stable state.  A check for a stable
 277                                  * state was done in jtag_add_clocks()
 278                                  */
 279                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 280                                 break;
 281
 282                         case JTAG_STATEMOVE:
 283 #ifdef _DEBUG_JTAG_IO_
 284                                 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
 285 #endif
 286                                 bitbang_end_state(cmd->cmd.statemove->end_state);
 287                                 bitbang_state_move(0);
 288                                 break;
 289                         case JTAG_PATHMOVE:
 290 #ifdef _DEBUG_JTAG_IO_
 291                                 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
 292                                         tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 293 #endif
 294                                 bitbang_path_move(cmd->cmd.pathmove);
 295                                 break;
 296                         case JTAG_SCAN:
 297 #ifdef _DEBUG_JTAG_IO_
 298                                 LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state));
 299 #endif
 300                                 bitbang_end_state(cmd->cmd.scan->end_state);
 301                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 302                                 type = jtag_scan_type(cmd->cmd.scan);
 303                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 304                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 305                                         retval = ERROR_JTAG_QUEUE_FAILED;
 306                                 if (buffer)
 307                                         free(buffer);
 308                                 break;
 309                         case JTAG_SLEEP:
 310 #ifdef _DEBUG_JTAG_IO_
 311                                 LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us);
 312 #endif
 313                                 jtag_sleep(cmd->cmd.sleep->us);
 314                                 break;
 315                         default:
 316                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 317                                 exit(-1);
 318                 }
 319                 cmd = cmd->next;
 320         }
 321         if (bitbang_interface->blink)
 322                 bitbang_interface->blink(0);
 323
 324         return retval;
 325 }