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
  81         for (i = skip; i < 7; i++)
  82         {
  83                 tms = (tms_scan >> i) & 1;
  84                 bitbang_interface->write(0, tms, 0);
  85                 bitbang_interface->write(1, tms, 0);
  86         }
  87         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  88
  89         tap_set_state(tap_get_end_state());
  90 }
  91
  92 static void bitbang_path_move(pathmove_command_t *cmd)
  93 {
  94         int num_states = cmd->num_states;
  95         int state_count;
  96         int tms = 0;
  97
  98         state_count = 0;
  99         while (num_states)
 100         {
 101                 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
 102                 {
 103                         tms = 0;
 104                 }
 105                 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
 106                 {
 107                         tms = 1;
 108                 }
 109                 else
 110                 {
 111                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
 112                         exit(-1);
 113                 }
 114
 115                 bitbang_interface->write(0, tms, 0);
 116                 bitbang_interface->write(1, tms, 0);
 117
 118                 tap_set_state(cmd->path[state_count]);
 119                 state_count++;
 120                 num_states--;
 121         }
 122
 123         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 124
 125         tap_set_end_state(tap_get_state());
 126 }
 127
 128 static void bitbang_runtest(int num_cycles)
 129 {
 130         int i;
 131
 132         tap_state_t saved_end_state = tap_get_end_state();
 133
 134         /* only do a state_move when we're not already in IDLE */
 135         if (tap_get_state() != TAP_IDLE)
 136         {
 137                 bitbang_end_state(TAP_IDLE);
 138                 bitbang_state_move(0);
 139         }
 140
 141         /* execute num_cycles */
 142         for (i = 0; i < num_cycles; i++)
 143         {
 144                 bitbang_interface->write(0, 0, 0);
 145                 bitbang_interface->write(1, 0, 0);
 146         }
 147         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 148
 149         /* finish in end_state */
 150         bitbang_end_state(saved_end_state);
 151         if (tap_get_state() != tap_get_end_state())
 152                 bitbang_state_move(0);
 153 }
 154
 155
 156 static void bitbang_stableclocks(int num_cycles)
 157 {
 158         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 159         int i;
 160
 161         /* send num_cycles clocks onto the cable */
 162         for (i = 0; i < num_cycles; i++)
 163         {
 164                 bitbang_interface->write(1, tms, 0);
 165                 bitbang_interface->write(0, tms, 0);
 166         }
 167 }
 168
 169
 170
 171 static void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 172 {
 173         tap_state_t saved_end_state = tap_get_end_state();
 174         int bit_cnt;
 175
 176         if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
 177         {
 178                 if (ir_scan)
 179                         bitbang_end_state(TAP_IRSHIFT);
 180                 else
 181                         bitbang_end_state(TAP_DRSHIFT);
 182
 183                 bitbang_state_move(0);
 184                 bitbang_end_state(saved_end_state);
 185         }
 186
 187         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 188         {
 189                 int val=0;
 190                 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
 191                 int tdi;
 192                 int bytec=bit_cnt/8;
 193                 int bcval=1<<(bit_cnt % 8);
 194
 195                 /* if we're just reading the scan, but don't care about the output
 196                  * default to outputting 'low', this also makes valgrind traces more readable,
 197                  * as it removes the dependency on an uninitialised value
 198                  */
 199                 tdi=0;
 200                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 201                         tdi=1;
 202
 203                 bitbang_interface->write(0, tms, tdi);
 204
 205                 if (type!=SCAN_OUT)
 206                         val=bitbang_interface->read();
 207
 208                 bitbang_interface->write(1, tms, tdi);
 209
 210                 if (type != SCAN_OUT)
 211                 {
 212                         if (val)
 213                                 buffer[bytec] |= bcval;
 214                         else
 215                                 buffer[bytec] &= ~bcval;
 216                 }
 217         }
 218
 219         if (tap_get_state() != tap_get_end_state())
 220         {
 221                 /* we *KNOW* the above loop transitioned out of
 222                  * the shift state, so we skip the first state
 223                  * and move directly to the end state.
 224                  */
 225                 bitbang_state_move(1);
 226         }
 227 }
 228
 229 int bitbang_execute_queue(void)
 230 {
 231         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 232         int scan_size;
 233         enum scan_type type;
 234         u8 *buffer;
 235         int retval;
 236
 237         if (!bitbang_interface)
 238         {
 239                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 240                 exit(-1);
 241         }
 242
 243         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 244          * that wasn't handled by a caller-provided error handler
 245          */
 246         retval = ERROR_OK;
 247
 248         if(bitbang_interface->blink)
 249                 bitbang_interface->blink(1);
 250
 251         while (cmd)
 252         {
 253                 switch (cmd->type)
 254                 {
 255                         case JTAG_END_STATE:
 256 #ifdef _DEBUG_JTAG_IO_
 257                                 LOG_DEBUG("end_state: %s", tap_state_name(cmd->cmd.end_state->end_state) );
 258 #endif
 259                                 if (cmd->cmd.end_state->end_state != TAP_INVALID)
 260                                         bitbang_end_state(cmd->cmd.end_state->end_state);
 261                                 break;
 262                         case JTAG_RESET:
 263 #ifdef _DEBUG_JTAG_IO_
 264                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 265 #endif
 266                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 267                                 {
 268                                         tap_set_state(TAP_RESET);
 269                                 }
 270                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 271                                 break;
 272                         case JTAG_RUNTEST:
 273 #ifdef _DEBUG_JTAG_IO_
 274                                 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
 275 #endif
 276                                 if (cmd->cmd.runtest->end_state != TAP_INVALID)
 277                                         bitbang_end_state(cmd->cmd.runtest->end_state);
 278                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 279                                 break;
 280
 281                         case JTAG_STABLECLOCKS:
 282                                 /* this is only allowed while in a stable state.  A check for a stable
 283                                  * state was done in jtag_add_clocks()
 284                                  */
 285                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 286                                 break;
 287
 288                         case JTAG_STATEMOVE:
 289 #ifdef _DEBUG_JTAG_IO_
 290                                 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
 291 #endif
 292                                 if (cmd->cmd.statemove->end_state != TAP_INVALID)
 293                                         bitbang_end_state(cmd->cmd.statemove->end_state);
 294                                 bitbang_state_move(0);
 295                                 break;
 296                         case JTAG_PATHMOVE:
 297 #ifdef _DEBUG_JTAG_IO_
 298                                 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
 299                                         tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 300 #endif
 301                                 bitbang_path_move(cmd->cmd.pathmove);
 302                                 break;
 303                         case JTAG_SCAN:
 304 #ifdef _DEBUG_JTAG_IO_
 305                                 LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
 306 #endif
 307                                 if (cmd->cmd.scan->end_state != TAP_INVALID)
 308                                         bitbang_end_state(cmd->cmd.scan->end_state);
 309                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 310                                 type = jtag_scan_type(cmd->cmd.scan);
 311                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 312                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 313                                         retval = ERROR_JTAG_QUEUE_FAILED;
 314                                 if (buffer)
 315                                         free(buffer);
 316                                 break;
 317                         case JTAG_SLEEP:
 318 #ifdef _DEBUG_JTAG_IO_
 319                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 320 #endif
 321                                 jtag_sleep(cmd->cmd.sleep->us);
 322                                 break;
 323                         default:
 324                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 325                                 exit(-1);
 326                 }
 327                 cmd = cmd->next;
 328         }
 329         if(bitbang_interface->blink)
 330                 bitbang_interface->blink(0);
 331
 332         return retval;
 333 }