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 #define INCLUDE_JTAG_INTERFACE_H
  29 #include "jtag.h"
  30 #include "interface.h"
  31
  32 /**
  33  * Function bitbang_stableclocks
  34  * issues a number of clock cycles while staying in a stable state.
  35  * Because the TMS value required to stay in the RESET state is a 1, whereas
  36  * the TMS value required to stay in any of the other stable states is a 0,
  37  * this function checks the current stable state to decide on the value of TMS
  38  * to use.
  39  */
  40 static void bitbang_stableclocks(int num_cycles);
  41
  42
  43 bitbang_interface_t *bitbang_interface;
  44
  45 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
  46  *
  47  * Set this to 1 and str912 reset halt will fail.
  48  *
  49  * If someone can submit a patch with an explanation it will be greatly
  50  * appreciated, but as far as I can tell (ØH) DCLK is generated upon
  51  * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
  52  * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
  53  * state". With hardware there is no such thing as *while* in a state. There
  54  * are only edges. So clk => 0 is in fact a very subtle state transition that
  55  * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
  56  *
  57  * For "reset halt" the last thing that happens before srst is asserted
  58  * is that the breakpoint is set up. If DCLK is not wiggled one last
  59  * time before the reset, then the breakpoint is not set up and
  60  * "reset halt" will fail to halt.
  61  *
  62  */
  63 #define CLOCK_IDLE() 0
  64
  65
  66 /* The bitbang driver leaves the TCK 0 when in idle */
  67 static void bitbang_end_state(tap_state_t state)
  68 {
  69         if (tap_is_state_stable(state))
  70                 tap_set_end_state(state);
  71         else
  72         {
  73                 LOG_ERROR("BUG: %i is not a valid end state", state);
  74                 exit(-1);
  75         }
  76 }
  77
  78 static void bitbang_state_move(int skip)
  79 {
  80         int i=0, tms=0;
  81         u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
  82         int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
  83
  84         for (i = skip; i < tms_count; i++)
  85         {
  86                 tms = (tms_scan >> i) & 1;
  87                 bitbang_interface->write(0, tms, 0);
  88                 bitbang_interface->write(1, tms, 0);
  89         }
  90         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
  91
  92         tap_set_state(tap_get_end_state());
  93 }
  94
  95 static void bitbang_path_move(pathmove_command_t *cmd)
  96 {
  97         int num_states = cmd->num_states;
  98         int state_count;
  99         int tms = 0;
 100
 101         state_count = 0;
 102         while (num_states)
 103         {
 104                 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
 105                 {
 106                         tms = 0;
 107                 }
 108                 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
 109                 {
 110                         tms = 1;
 111                 }
 112                 else
 113                 {
 114                         LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
 115                         exit(-1);
 116                 }
 117
 118                 bitbang_interface->write(0, tms, 0);
 119                 bitbang_interface->write(1, tms, 0);
 120
 121                 tap_set_state(cmd->path[state_count]);
 122                 state_count++;
 123                 num_states--;
 124         }
 125
 126         bitbang_interface->write(CLOCK_IDLE(), tms, 0);
 127
 128         tap_set_end_state(tap_get_state());
 129 }
 130
 131 static void bitbang_runtest(int num_cycles)
 132 {
 133         int i;
 134
 135         tap_state_t saved_end_state = tap_get_end_state();
 136
 137         /* only do a state_move when we're not already in IDLE */
 138         if (tap_get_state() != TAP_IDLE)
 139         {
 140                 bitbang_end_state(TAP_IDLE);
 141                 bitbang_state_move(0);
 142         }
 143
 144         /* execute num_cycles */
 145         for (i = 0; i < num_cycles; i++)
 146         {
 147                 bitbang_interface->write(0, 0, 0);
 148                 bitbang_interface->write(1, 0, 0);
 149         }
 150         bitbang_interface->write(CLOCK_IDLE(), 0, 0);
 151
 152         /* finish in end_state */
 153         bitbang_end_state(saved_end_state);
 154         if (tap_get_state() != tap_get_end_state())
 155                 bitbang_state_move(0);
 156 }
 157
 158
 159 static void bitbang_stableclocks(int num_cycles)
 160 {
 161         int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
 162         int i;
 163
 164         /* send num_cycles clocks onto the cable */
 165         for (i = 0; i < num_cycles; i++)
 166         {
 167                 bitbang_interface->write(1, tms, 0);
 168                 bitbang_interface->write(0, tms, 0);
 169         }
 170 }
 171
 172
 173
 174 static void bitbang_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size)
 175 {
 176         tap_state_t saved_end_state = tap_get_end_state();
 177         int bit_cnt;
 178
 179         if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
 180         {
 181                 if (ir_scan)
 182                         bitbang_end_state(TAP_IRSHIFT);
 183                 else
 184                         bitbang_end_state(TAP_DRSHIFT);
 185
 186                 bitbang_state_move(0);
 187                 bitbang_end_state(saved_end_state);
 188         }
 189
 190         for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
 191         {
 192                 int val=0;
 193                 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
 194                 int tdi;
 195                 int bytec=bit_cnt/8;
 196                 int bcval=1<<(bit_cnt % 8);
 197
 198                 /* if we're just reading the scan, but don't care about the output
 199                  * default to outputting 'low', this also makes valgrind traces more readable,
 200                  * as it removes the dependency on an uninitialised value
 201                  */
 202                 tdi=0;
 203                 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
 204                         tdi=1;
 205
 206                 bitbang_interface->write(0, tms, tdi);
 207
 208                 if (type!=SCAN_OUT)
 209                         val=bitbang_interface->read();
 210
 211                 bitbang_interface->write(1, tms, tdi);
 212
 213                 if (type != SCAN_OUT)
 214                 {
 215                         if (val)
 216                                 buffer[bytec] |= bcval;
 217                         else
 218                                 buffer[bytec] &= ~bcval;
 219                 }
 220         }
 221
 222         if (tap_get_state() != tap_get_end_state())
 223         {
 224                 /* we *KNOW* the above loop transitioned out of
 225                  * the shift state, so we skip the first state
 226                  * and move directly to the end state.
 227                  */
 228                 bitbang_state_move(1);
 229         }
 230 }
 231
 232 int bitbang_execute_queue(void)
 233 {
 234         jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
 235         int scan_size;
 236         enum scan_type type;
 237         u8 *buffer;
 238         int retval;
 239
 240         if (!bitbang_interface)
 241         {
 242                 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
 243                 exit(-1);
 244         }
 245
 246         /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
 247          * that wasn't handled by a caller-provided error handler
 248          */
 249         retval = ERROR_OK;
 250
 251         if(bitbang_interface->blink)
 252                 bitbang_interface->blink(1);
 253
 254         while (cmd)
 255         {
 256                 switch (cmd->type)
 257                 {
 258                         case JTAG_RESET:
 259 #ifdef _DEBUG_JTAG_IO_
 260                                 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 261 #endif
 262                                 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 263                                 {
 264                                         tap_set_state(TAP_RESET);
 265                                 }
 266                                 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 267                                 break;
 268                         case JTAG_RUNTEST:
 269 #ifdef _DEBUG_JTAG_IO_
 270                                 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
 271 #endif
 272                                 bitbang_end_state(cmd->cmd.runtest->end_state);
 273                                 bitbang_runtest(cmd->cmd.runtest->num_cycles);
 274                                 break;
 275
 276                         case JTAG_STABLECLOCKS:
 277                                 /* this is only allowed while in a stable state.  A check for a stable
 278                                  * state was done in jtag_add_clocks()
 279                                  */
 280                                 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
 281                                 break;
 282
 283                         case JTAG_STATEMOVE:
 284 #ifdef _DEBUG_JTAG_IO_
 285                                 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
 286 #endif
 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                                 bitbang_end_state(cmd->cmd.scan->end_state);
 302                                 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
 303                                 type = jtag_scan_type(cmd->cmd.scan);
 304                                 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
 305                                 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
 306                                         retval = ERROR_JTAG_QUEUE_FAILED;
 307                                 if (buffer)
 308                                         free(buffer);
 309                                 break;
 310                         case JTAG_SLEEP:
 311 #ifdef _DEBUG_JTAG_IO_
 312                                 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
 313 #endif
 314                                 jtag_sleep(cmd->cmd.sleep->us);
 315                                 break;
 316                         default:
 317                                 LOG_ERROR("BUG: unknown JTAG command type encountered");
 318                                 exit(-1);
 319                 }
 320                 cmd = cmd->next;
 321         }
 322         if(bitbang_interface->blink)
 323                 bitbang_interface->blink(0);
 324
 325         return retval;
 326 }