src/jtag/dummy.c

   1 /***************************************************************************
   2  *   Copyright (C) 2008 by Øyvind Harboe                                   *
   3  *   oyvind.harboe@zylin.com                                               *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include "replacements.h"
  25
  26 #include "jtag.h"
  27 #include "bitbang.h"
  28
  29
  30 /* my private tap controller state, which tracks state for calling code */
  31 static tap_state_t dummy_state = TAP_RESET;
  32
  33 static int dummy_clock;         /* edge detector */
  34
  35 static int clock_count;         /* count clocks in any stable state, only stable states */
  36
  37
  38 static tap_state_t tap_state_transition(tap_state_t cur_state, int tms);
  39
  40 static u32 dummy_data;
  41
  42
  43 int dummy_speed(int speed);
  44 int dummy_register_commands(struct command_context_s *cmd_ctx);
  45 int dummy_init(void);
  46 int dummy_quit(void);
  47 static int dummy_khz(int khz, int *jtag_speed);
  48 static int dummy_speed_div(int speed, int *khz);
  49
  50
  51 /* The dummy driver is used to easily check the code path
  52  * where the target is unresponsive.
  53  */
  54 jtag_interface_t dummy_interface =
  55 {
  56         .name = "dummy",
  57
  58         .execute_queue = bitbang_execute_queue,
  59
  60         .speed = dummy_speed,
  61         .register_commands = dummy_register_commands,
  62         .khz = dummy_khz,
  63         .speed_div = dummy_speed_div,
  64
  65         .init = dummy_init,
  66         .quit = dummy_quit,
  67 };
  68
  69 int dummy_read(void);
  70 void dummy_write(int tck, int tms, int tdi);
  71 void dummy_reset(int trst, int srst);
  72 void dummy_led(int on);
  73
  74 bitbang_interface_t dummy_bitbang =
  75 {
  76         .read = dummy_read,
  77         .write = dummy_write,
  78         .reset = dummy_reset,
  79         .blink = dummy_led
  80 };
  81
  82 int dummy_read(void)
  83 {
  84         int data = 1 & dummy_data;
  85         dummy_data = (dummy_data >> 1) | (1<<31);
  86         return data;
  87 }
  88
  89
  90 void dummy_write(int tck, int tms, int tdi)
  91 {
  92         /* TAP standard: "state transitions occur on rising edge of clock" */
  93         if( tck != dummy_clock )
  94         {
  95                 if( tck )
  96                 {
  97                         int old_state = dummy_state;
  98                         dummy_state = tap_state_transition( old_state, tms );
  99
 100                         if( old_state != dummy_state )
 101                         {
 102                                 if( clock_count )
 103                                 {
 104                                         LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
 105                                         clock_count = 0;
 106                                 }
 107
 108                                 LOG_DEBUG("dummy_tap: %s", jtag_state_name(dummy_state) );
 109
 110 #if defined(DEBUG)
 111                                 if(dummy_state == TAP_DRCAPTURE)
 112                                         dummy_data = 0x01255043;
 113 #endif
 114                         }
 115                         else
 116                         {
 117                                 /* this is a stable state clock edge, no change of state here,
 118                                  * simply increment clock_count for subsequent logging
 119                                  */
 120                                 ++clock_count;
 121                         }
 122                 }
 123                 dummy_clock = tck;
 124         }
 125 }
 126
 127 void dummy_reset(int trst, int srst)
 128 {
 129         dummy_clock = 0;
 130
 131         if (trst || (srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
 132                 dummy_state = TAP_RESET;
 133
 134         LOG_DEBUG("reset to: %s", jtag_state_name(dummy_state) );
 135 }
 136
 137 static int dummy_khz(int khz, int *jtag_speed)
 138 {
 139         if (khz==0)
 140         {
 141                 *jtag_speed=0;
 142         }
 143         else
 144         {
 145                 *jtag_speed=64000/khz;
 146         }
 147         return ERROR_OK;
 148 }
 149
 150 static int dummy_speed_div(int speed, int *khz)
 151 {
 152         if (speed==0)
 153         {
 154                 *khz = 0;
 155         }
 156         else
 157         {
 158                 *khz=64000/speed;
 159         }
 160
 161         return ERROR_OK;
 162 }
 163
 164 int dummy_speed(int speed)
 165 {
 166         return ERROR_OK;
 167 }
 168
 169 int dummy_register_commands(struct command_context_s *cmd_ctx)
 170 {
 171         return ERROR_OK;
 172 }
 173
 174 int dummy_init(void)
 175 {
 176         bitbang_interface = &dummy_bitbang;
 177
 178         return ERROR_OK;
 179 }
 180
 181 int dummy_quit(void)
 182 {
 183         return ERROR_OK;
 184 }
 185
 186 void dummy_led(int on)
 187 {
 188 }
 189
 190
 191 /**
 192  * Function tap_state_transition
 193  * takes a current TAP state and returns the next state according to the tms value.
 194  *
 195  * Even though there is code to duplicate this elsewhere, we do it here a little
 196  * differently just to get a second opinion, i.e. a verification, on state tracking
 197  * in that other logic. Plus array lookups without index checking are no favorite thing.
 198  * This is educational for developers new to TAP controllers.
 199  */
 200 static tap_state_t tap_state_transition(tap_state_t cur_state, int tms)
 201 {
 202         tap_state_t new_state;
 203
 204         if (tms)
 205         {
 206                 switch (cur_state)
 207                 {
 208                 case TAP_RESET:
 209                         new_state = cur_state;
 210                         break;
 211                 case TAP_IDLE:
 212                 case TAP_DRUPDATE:
 213                 case TAP_IRUPDATE:
 214                         new_state = TAP_DRSELECT;
 215                         break;
 216                 case TAP_DRSELECT:
 217                         new_state = TAP_IRSELECT;
 218                         break;
 219                 case TAP_DRCAPTURE:
 220                 case TAP_DRSHIFT:
 221                         new_state = TAP_DREXIT1;
 222                         break;
 223                 case TAP_DREXIT1:
 224                 case TAP_DREXIT2:
 225                         new_state = TAP_DRUPDATE;
 226                         break;
 227                 case TAP_DRPAUSE:
 228                         new_state = TAP_DREXIT2;
 229                         break;
 230                 case TAP_IRSELECT:
 231                         new_state = TAP_RESET;
 232                         break;
 233                 case TAP_IRCAPTURE:
 234                 case TAP_IRSHIFT:
 235                         new_state = TAP_IREXIT1;
 236                         break;
 237                 case TAP_IREXIT1:
 238                 case TAP_IREXIT2:
 239                         new_state = TAP_IRUPDATE;
 240                         break;
 241                 case TAP_IRPAUSE:
 242                         new_state = TAP_IREXIT2;
 243                         break;
 244                 default:
 245                         LOG_ERROR( "fatal: invalid argument cur_state=%d", cur_state );
 246                         exit(1);
 247                         break;
 248                 }
 249         }
 250         else
 251         {
 252                 switch (cur_state)
 253                 {
 254                 case TAP_RESET:
 255                 case TAP_IDLE:
 256                 case TAP_DRUPDATE:
 257                 case TAP_IRUPDATE:
 258                         new_state = TAP_IDLE;
 259                         break;
 260                 case TAP_DRSELECT:
 261                         new_state = TAP_DRCAPTURE;
 262                         break;
 263                 case TAP_DRCAPTURE:
 264                 case TAP_DRSHIFT:
 265                 case TAP_DREXIT2:
 266                         new_state = TAP_DRSHIFT;
 267                         break;
 268                 case TAP_DREXIT1:
 269                 case TAP_DRPAUSE:
 270                         new_state = TAP_DRPAUSE;
 271                         break;
 272                 case TAP_IRSELECT:
 273                         new_state = TAP_IRCAPTURE;
 274                         break;
 275                 case TAP_IRCAPTURE:
 276                 case TAP_IRSHIFT:
 277                 case TAP_IREXIT2:
 278                         new_state = TAP_IRSHIFT;
 279                         break;
 280                 case TAP_IREXIT1:
 281                 case TAP_IRPAUSE:
 282                         new_state = TAP_IRPAUSE;
 283                         break;
 284                 default:
 285                         LOG_ERROR( "fatal: invalid argument cur_state=%d", cur_state );
 286                         exit(1);
 287                         break;
 288                 }
 289         }
 290
 291         return new_state;
 292 }