src/jtag/drivers/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
  21 #ifdef HAVE_CONFIG_H
  22 #include "config.h"
  23 #endif
  24
  25 #include <jtag/interface.h>
  26 #include "bitbang.h"
  27 #include "hello.h"
  28
  29 /* my private tap controller state, which tracks state for calling code */
  30 static tap_state_t dummy_state = TAP_RESET;
  31
  32 static int dummy_clock;         /* edge detector */
  33
  34 static int clock_count;         /* count clocks in any stable state, only stable states */
  35
  36 static uint32_t dummy_data;
  37
  38 static int dummy_read(void)
  39 {
  40         int data = 1 & dummy_data;
  41         dummy_data = (dummy_data >> 1) | (1 << 31);
  42         return data;
  43 }
  44
  45 static void dummy_write(int tck, int tms, int tdi)
  46 {
  47         /* TAP standard: "state transitions occur on rising edge of clock" */
  48         if (tck != dummy_clock) {
  49                 if (tck) {
  50                         tap_state_t old_state = dummy_state;
  51                         dummy_state = tap_state_transition(old_state, tms);
  52
  53                         if (old_state != dummy_state) {
  54                                 if (clock_count) {
  55                                         LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
  56                                         clock_count = 0;
  57                                 }
  58
  59                                 LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));
  60
  61 #if defined(DEBUG)
  62                                 if (dummy_state == TAP_DRCAPTURE)
  63                                         dummy_data = 0x01255043;
  64 #endif
  65                         } else {
  66                                 /* this is a stable state clock edge, no change of state here,
  67                                  * simply increment clock_count for subsequent logging
  68                                  */
  69                                 ++clock_count;
  70                         }
  71                 }
  72                 dummy_clock = tck;
  73         }
  74 }
  75
  76 static void dummy_reset(int trst, int srst)
  77 {
  78         dummy_clock = 0;
  79
  80         if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
  81                 dummy_state = TAP_RESET;
  82
  83         LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
  84 }
  85
  86 static void dummy_led(int on)
  87 {
  88 }
  89
  90 static struct bitbang_interface dummy_bitbang = {
  91                 .read = &dummy_read,
  92                 .write = &dummy_write,
  93                 .reset = &dummy_reset,
  94                 .blink = &dummy_led,
  95         };
  96
  97 static int dummy_khz(int khz, int *jtag_speed)
  98 {
  99         if (khz == 0)
 100                 *jtag_speed = 0;
 101         else
 102                 *jtag_speed = 64000/khz;
 103         return ERROR_OK;
 104 }
 105
 106 static int dummy_speed_div(int speed, int *khz)
 107 {
 108         if (speed == 0)
 109                 *khz = 0;
 110         else
 111                 *khz = 64000/speed;
 112
 113         return ERROR_OK;
 114 }
 115
 116 static int dummy_speed(int speed)
 117 {
 118         return ERROR_OK;
 119 }
 120
 121 static int dummy_init(void)
 122 {
 123         bitbang_interface = &dummy_bitbang;
 124
 125         return ERROR_OK;
 126 }
 127
 128 static int dummy_quit(void)
 129 {
 130         return ERROR_OK;
 131 }
 132
 133 static const struct command_registration dummy_command_handlers[] = {
 134         {
 135                 .name = "dummy",
 136                 .mode = COMMAND_ANY,
 137                 .help = "dummy interface driver commands",
 138
 139                 .chain = hello_command_handlers,
 140         },
 141         COMMAND_REGISTRATION_DONE,
 142 };
 143
 144 /* The dummy driver is used to easily check the code path
 145  * where the target is unresponsive.
 146  */
 147 struct jtag_interface dummy_interface = {
 148                 .name = "dummy",
 149
 150                 .supported = DEBUG_CAP_TMS_SEQ,
 151                 .commands = dummy_command_handlers,
 152                 .transports = jtag_only,
 153
 154                 .execute_queue = &bitbang_execute_queue,
 155
 156                 .speed = &dummy_speed,
 157                 .khz = &dummy_khz,
 158                 .speed_div = &dummy_speed_div,
 159
 160                 .init = &dummy_init,
 161                 .quit = &dummy_quit,
 162         };