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 "jtag.h"
  29
  30 /**
  31  * Function bitbang_stableclocks
  32  * issues a number of clock cycles while staying in a stable state.
  33  * Because the TMS value required to stay in the RESET state is a 1, whereas
  34  * the TMS value required to stay in any of the other stable states is a 0,
  35  * this function checks the current stable state to decide on the value of TMS
  36  * to use.
  37  */
  38 static void bitbang_stableclocks(int num_cycles);
  39
  40
  41 bitbang_interface_t *bitbang_interface;
  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
  64 /* The bitbang driver leaves the TCK 0 when in idle */
  65 static void bitbang_end_state(tap_state_t state)
  66 {
  67         if (tap_is_state_stable(state))
  68                 tap_set_end_state(state);
  69         else
  70         {
  71                 LOG_ERROR("BUG: %i is not a valid end state", state);
  72                 exit(-1);
  73         }
  74 }
  75
  76 static void bitbang_state_move(int skip)
  77 {
  78         int i=0, tms=0;
  79         u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
  80         int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
  81
  82         for (i = skip; i < tms_count; i++)
  83         {
  84                 tms = (tms_scan >> i) & 1;
  85                 bitbang_interface->write(0, tms, 0);
  86                 bitbang_interface->write(1, tms, 0);
  87         }
  88         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  89
  90         tap_set_state(tap_get_end_state());
  91 }
  92
  93 static void bitbang_path_move(pathmove_command_t *cmd)
  94 {
  95         int num_states = cmd->num_states;
  96         int state_count;
  97         int tms = 0;
  98
  99         state_count = 0;
 100         while (num_states)
 101         {
 102                 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
 103                 {
 104                         tms = 0;
 105                 }
 106                 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
 107                 {
 108                         tms = 1;
 109                 }
 110                 else
 111                 {
 112                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
 113                         exit(-1);
 114                 }
 115
 116                 bitbang_interface->write(0, tms, 0);
 117                 bitbang_interface->write(1, tms, 0);
 118
 119                 tap_set_state(cmd->path[state_count]);
 120                 state_count++;
 121                 num_states--;
 122         }
 123
 124         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 125
 126         tap_set_end_state(tap_get_state());
 127 }
 128
 129 static void bitbang_runtest(int num_cycles)
 130 {
 131         int i;
 132
 133         tap_state_t saved_end_state = tap_get_end_state();
 134
 135         /* only do a state_move when we're not already in IDLE */
 136         if (tap_get_state() != TAP_IDLE)
 137         {
 138                 bitbang_end_state(TAP_IDLE);
 139                 bitbang_state_move(0);
 140         }
 141
 142         /* execute num_cycles */
 143         for (i = 0; i < num_cycles; i++)
 144         {
 145                 bitbang_interface->write(0, 0, 0);
 146                 bitbang_interface->write(1, 0, 0);
 147         }
 148         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 149
 150         /* finish in end_state */
 151         bitbang_end_state(saved_end_state);
 152         if (tap_get_state() != tap_get_end_state())
 153                 bitbang_state_move(0);
 154 }
 155
 156
 157 static void bitbang_stableclocks(int num_cycles)
 158 {
 159         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 160         int i;
 161
 162         /* send num_cycles clocks onto the cable */
 163         for (i = 0; i < num_cycles; i++)
 164         {
 165                 bitbang_interface->write(1, tms, 0);
 166                 bitbang_interface->write(0, tms, 0);
 167         }
 168 }
 169
 170
 171
 172 static void bitbang_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 173 {
 174         tap_state_t saved_end_state = tap_get_end_state();
 175         int bit_cnt;
 176
 177         if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
 178         {
 179                 if (ir_scan)
 180                         bitbang_end_state(TAP_IRSHIFT);
 181                 else
 182                         bitbang_end_state(TAP_DRSHIFT);
 183
 184                 bitbang_state_move(0);
 185                 bitbang_end_state(saved_end_state);
 186         }
 187
 188         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 189         {
 190                 int val=0;
 191                 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
 192                 int tdi;
 193                 int bytec=bit_cnt/8;
 194                 int bcval=1<<(bit_cnt % 8);
 195
 196                 /* if we're just reading the scan, but don't care about the output
 197                  * default to outputting 'low', this also makes valgrind traces more readable,
 198                  * as it removes the dependency on an uninitialised value
 199                  */
 200                 tdi=0;
 201                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 202                         tdi=1;
 203
 204                 bitbang_interface->write(0, tms, tdi);
 205
 206                 if (type!=SCAN_OUT)
 207                         val=bitbang_interface->read();
 208
 209                 bitbang_interface->write(1, tms, tdi);
 210
 211                 if (type != SCAN_OUT)
 212                 {
 213                         if (val)
 214                                 buffer[bytec] |= bcval;
 215                         else
 216                                 buffer[bytec] &= ~bcval;
 217                 }
 218         }
 219
 220         if (tap_get_state() != tap_get_end_state())
 221         {
 222                 /* we *KNOW* the above loop transitioned out of
 223                  * the shift state, so we skip the first state
 224                  * and move directly to the end state.
 225                  */
 226                 bitbang_state_move(1);
 227         }
 228 }
 229
 230 int bitbang_execute_queue(void)
 231 {
 232         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 233         int scan_size;
 234         enum scan_type type;
 235         u8 *buffer;
 236         int retval;
 237
 238         if (!bitbang_interface)
 239         {
 240                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 241                 exit(-1);
 242         }
 243
 244         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 245          * that wasn't handled by a caller-provided error handler
 246          */
 247         retval = ERROR_OK;
 248
 249         if(bitbang_interface->blink)
 250                 bitbang_interface->blink(1);
 251
 252         while (cmd)
 253         {
 254                 switch (cmd->type)
 255                 {
 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                                         tap_set_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 %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
 269 #endif
 270                                 if (cmd->cmd.runtest->end_state != TAP_INVALID)
 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                                 if (cmd->cmd.statemove->end_state != TAP_INVALID)
 287                                         bitbang_end_state(cmd->cmd.statemove->end_state);
 288                                 bitbang_state_move(0);
 289                                 break;
 290                         case JTAG_PATHMOVE:
 291 #ifdef _DEBUG_JTAG_IO_
 292                                 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
 293                                         tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 294 #endif
 295                                 bitbang_path_move(cmd->cmd.pathmove);
 296                                 break;
 297                         case JTAG_SCAN:
 298 #ifdef _DEBUG_JTAG_IO_
 299                                 LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
 300 #endif
 301                                 if (cmd->cmd.scan->end_state != TAP_INVALID)
 302                                         bitbang_end_state(cmd->cmd.scan->end_state);
 303                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 304                                 type = jtag_scan_type(cmd->cmd.scan);
 305                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 306                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 307                                         retval = ERROR_JTAG_QUEUE_FAILED;
 308                                 if (buffer)
 309                                         free(buffer);
 310                                 break;
 311                         case JTAG_SLEEP:
 312 #ifdef _DEBUG_JTAG_IO_
 313                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 314 #endif
 315                                 jtag_sleep(cmd->cmd.sleep->us);
 316                                 break;
 317                         default:
 318                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 319                                 exit(-1);
 320                 }
 321                 cmd = cmd->next;
 322         }
 323         if(bitbang_interface->blink)
 324                 bitbang_interface->blink(0);
 325
 326         return retval;
 327 }