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
  41 /**
  42  * Function bitbang_stableclocks
  43  * issues a number of clock cycles while staying in a stable state.
  44  * Because the TMS value required to stay in the RESET state is a 1, whereas
  45  * the TMS value required to stay in any of the other stable states is a 0,
  46  * this function checks the current stable state to decide on the value of TMS
  47  * to use.
  48  */
  49 static void bitbang_stableclocks(int num_cycles);
  50
  51
  52 bitbang_interface_t *bitbang_interface;
  53
  54 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  55  *
  56  * Set this to 1 and str912 reset halt will fail.
  57  *
  58  * If someone can submit a patch with an explanation it will be greatly
  59  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  60  * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
  61  * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
  62  * state". With hardware there is no such thing as *while* in a state. There
  63  * are only edges. So clk => 0 is in fact a very subtle state transition that
  64  * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
  65  *
  66  * For "reset halt" the last thing that happens before srst is asserted
  67  * is that the breakpoint is set up. If DCLK is not wiggled one last
  68  * time before the reset, then the breakpoint is not set up and
  69  * "reset halt" will fail to halt.
  70  *
  71  */
  72 #define CLOCK_IDLE() 0
  73
  74
  75 /* The bitbang driver leaves the TCK 0 when in idle */
  76 static void bitbang_end_state(tap_state_t state)
  77 {
  78         if (tap_is_state_stable(state))
  79                 tap_set_end_state(state);
  80         else
  81         {
  82                 LOG_ERROR("BUG: %i is not a valid end state", state);
  83                 exit(-1);
  84         }
  85 }
  86
  87 static void bitbang_state_move(void)
  88 {
  89         int i=0, tms=0;
  90         u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
  91
  92         for (i = 0; i < 7; i++)
  93         {
  94                 tms = (tms_scan >> i) & 1;
  95                 bitbang_interface->write(0, tms, 0);
  96                 bitbang_interface->write(1, tms, 0);
  97         }
  98         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  99
 100         tap_set_state(tap_get_end_state());
 101 }
 102
 103 static void bitbang_path_move(pathmove_command_t *cmd)
 104 {
 105         int num_states = cmd->num_states;
 106         int state_count;
 107         int tms = 0;
 108
 109         state_count = 0;
 110         while (num_states)
 111         {
 112                 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
 113                 {
 114                         tms = 0;
 115                 }
 116                 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
 117                 {
 118                         tms = 1;
 119                 }
 120                 else
 121                 {
 122                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
 123                         exit(-1);
 124                 }
 125
 126                 bitbang_interface->write(0, tms, 0);
 127                 bitbang_interface->write(1, tms, 0);
 128
 129                 tap_set_state(cmd->path[state_count]);
 130                 state_count++;
 131                 num_states--;
 132         }
 133
 134         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 135
 136         tap_set_end_state(tap_get_state());
 137 }
 138
 139 static void bitbang_runtest(int num_cycles)
 140 {
 141         int i;
 142
 143         tap_state_t saved_end_state = tap_get_end_state();
 144
 145         /* only do a state_move when we're not already in IDLE */
 146         if (tap_get_state() != TAP_IDLE)
 147         {
 148                 bitbang_end_state(TAP_IDLE);
 149                 bitbang_state_move();
 150         }
 151
 152         /* execute num_cycles */
 153         for (i = 0; i < num_cycles; i++)
 154         {
 155                 bitbang_interface->write(0, 0, 0);
 156                 bitbang_interface->write(1, 0, 0);
 157         }
 158         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 159
 160         /* finish in end_state */
 161         bitbang_end_state(saved_end_state);
 162         if (tap_get_state() != tap_get_end_state())
 163                 bitbang_state_move();
 164 }
 165
 166
 167 static void bitbang_stableclocks(int num_cycles)
 168 {
 169         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 170         int i;
 171
 172         /* send num_cycles clocks onto the cable */
 173         for (i = 0; i < num_cycles; i++)
 174         {
 175                 bitbang_interface->write(1, tms, 0);
 176                 bitbang_interface->write(0, tms, 0);
 177         }
 178 }
 179
 180
 181
 182 static void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 183 {
 184         tap_state_t saved_end_state = tap_get_end_state();
 185         int bit_cnt;
 186
 187         if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
 188         {
 189                 if (ir_scan)
 190                         bitbang_end_state(TAP_IRSHIFT);
 191                 else
 192                         bitbang_end_state(TAP_DRSHIFT);
 193
 194                 bitbang_state_move();
 195                 bitbang_end_state(saved_end_state);
 196         }
 197
 198         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 199         {
 200                 int val=0;
 201                 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
 202                 int tdi;
 203                 int bytec=bit_cnt/8;
 204                 int bcval=1<<(bit_cnt % 8);
 205
 206                 /* if we're just reading the scan, but don't care about the output
 207                  * default to outputting 'low', this also makes valgrind traces more readable,
 208                  * as it removes the dependency on an uninitialised value
 209                  */
 210                 tdi=0;
 211                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 212                         tdi=1;
 213
 214                 bitbang_interface->write(0, tms, tdi);
 215
 216                 if (type!=SCAN_OUT)
 217                         val=bitbang_interface->read();
 218
 219                 bitbang_interface->write(1, tms, tdi);
 220
 221                 if (type != SCAN_OUT)
 222                 {
 223                         if (val)
 224                                 buffer[bytec] |= bcval;
 225                         else
 226                                 buffer[bytec] &= ~bcval;
 227                 }
 228         }
 229
 230         /* TAP_DRSHIFT & TAP_IRSHIFT are illegal end states, so we always transition to the pause
 231          * state which is a legal stable state from which statemove will work.
 232          *
 233          * Exit1 -> Pause
 234          */
 235         bitbang_interface->write(0, 0, 0);
 236         bitbang_interface->write(1, 0, 0);
 237         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 238
 239         if (ir_scan)
 240                 tap_set_state(TAP_IRPAUSE);
 241         else
 242                 tap_set_state(TAP_DRPAUSE);
 243
 244         if (tap_get_state() != tap_get_end_state())
 245                 bitbang_state_move();
 246 }
 247
 248 int bitbang_execute_queue(void)
 249 {
 250         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 251         int scan_size;
 252         enum scan_type type;
 253         u8 *buffer;
 254         int retval;
 255
 256         if (!bitbang_interface)
 257         {
 258                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 259                 exit(-1);
 260         }
 261
 262         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 263          * that wasn't handled by a caller-provided error handler
 264          */
 265         retval = ERROR_OK;
 266
 267         if(bitbang_interface->blink)
 268                 bitbang_interface->blink(1);
 269
 270         while (cmd)
 271         {
 272                 switch (cmd->type)
 273                 {
 274                         case JTAG_END_STATE:
 275 #ifdef _DEBUG_JTAG_IO_
 276                                 LOG_DEBUG("end_state: %s", tap_state_name(cmd->cmd.end_state->end_state) );
 277 #endif
 278                                 if (cmd->cmd.end_state->end_state != TAP_INVALID)
 279                                         bitbang_end_state(cmd->cmd.end_state->end_state);
 280                                 break;
 281                         case JTAG_RESET:
 282 #ifdef _DEBUG_JTAG_IO_
 283                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 284 #endif
 285                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 286                                 {
 287                                         tap_set_state(TAP_RESET);
 288                                 }
 289                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 290                                 break;
 291                         case JTAG_RUNTEST:
 292 #ifdef _DEBUG_JTAG_IO_
 293                                 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
 294 #endif
 295                                 if (cmd->cmd.runtest->end_state != TAP_INVALID)
 296                                         bitbang_end_state(cmd->cmd.runtest->end_state);
 297                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 298                                 break;
 299
 300                         case JTAG_STABLECLOCKS:
 301                                 /* this is only allowed while in a stable state.  A check for a stable
 302                                  * state was done in jtag_add_clocks()
 303                                  */
 304                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 305                                 break;
 306
 307                         case JTAG_STATEMOVE:
 308 #ifdef _DEBUG_JTAG_IO_
 309                                 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
 310 #endif
 311                                 if (cmd->cmd.statemove->end_state != TAP_INVALID)
 312                                         bitbang_end_state(cmd->cmd.statemove->end_state);
 313                                 bitbang_state_move();
 314                                 break;
 315                         case JTAG_PATHMOVE:
 316 #ifdef _DEBUG_JTAG_IO_
 317                                 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
 318                                         tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
 319 #endif
 320                                 bitbang_path_move(cmd->cmd.pathmove);
 321                                 break;
 322                         case JTAG_SCAN:
 323 #ifdef _DEBUG_JTAG_IO_
 324                                 LOG_DEBUG("%s scan end in %s",  (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
 325 #endif
 326                                 if (cmd->cmd.scan->end_state != TAP_INVALID)
 327                                         bitbang_end_state(cmd->cmd.scan->end_state);
 328                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 329                                 type = jtag_scan_type(cmd->cmd.scan);
 330                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 331                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 332                                         retval = ERROR_JTAG_QUEUE_FAILED;
 333                                 if (buffer)
 334                                         free(buffer);
 335                                 break;
 336                         case JTAG_SLEEP:
 337 #ifdef _DEBUG_JTAG_IO_
 338                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 339 #endif
 340                                 jtag_sleep(cmd->cmd.sleep->us);
 341                                 break;
 342                         default:
 343                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 344                                 exit(-1);
 345                 }
 346                 cmd = cmd->next;
 347         }
 348         if(bitbang_interface->blink)
 349                 bitbang_interface->blink(0);
 350
 351         return retval;
 352 }