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 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include <jtag/interface.h>
  25 #include "bitbang.h"
  26 #include "hello.h"
  27
  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
  39 static int dummy_read(void)
  40 {
  41         int data = 1 & dummy_data;
  42         dummy_data = (dummy_data >> 1) | (1 << 31);
  43         return data;
  44 }
  45
  46
  47 static void dummy_write(int tck, int tms, int tdi)
  48 {
  49         /* TAP standard: "state transitions occur on rising edge of clock" */
  50         if (tck != dummy_clock)
  51         {
  52                 if (tck)
  53                 {
  54                         tap_state_t old_state = dummy_state;
  55                         dummy_state = tap_state_transition(old_state, tms);
  56
  57                         if (old_state != dummy_state)
  58                         {
  59                                 if (clock_count)
  60                                 {
  61                                         LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
  62                                         clock_count = 0;
  63                                 }
  64
  65                                 LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));
  66
  67 #if defined(DEBUG)
  68                                 if (dummy_state == TAP_DRCAPTURE)
  69                                         dummy_data = 0x01255043;
  70 #endif
  71                         }
  72                         else
  73                         {
  74                                 /* this is a stable state clock edge, no change of state here,
  75                                  * simply increment clock_count for subsequent logging
  76                                  */
  77                                 ++clock_count;
  78                         }
  79                 }
  80                 dummy_clock = tck;
  81         }
  82 }
  83
  84 static void dummy_reset(int trst, int srst)
  85 {
  86         dummy_clock = 0;
  87
  88         if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
  89                 dummy_state = TAP_RESET;
  90
  91         LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
  92 }
  93
  94 static void dummy_led(int on)
  95 {
  96 }
  97
  98 static struct bitbang_interface dummy_bitbang = {
  99                 .read = &dummy_read,
 100                 .write = &dummy_write,
 101                 .reset = &dummy_reset,
 102                 .blink = &dummy_led,
 103         };
 104
 105
 106 static int dummy_khz(int khz, int *jtag_speed)
 107 {
 108         if (khz == 0)
 109         {
 110                 *jtag_speed = 0;
 111         }
 112         else
 113         {
 114                 *jtag_speed = 64000/khz;
 115         }
 116         return ERROR_OK;
 117 }
 118
 119 static int dummy_speed_div(int speed, int *khz)
 120 {
 121         if (speed == 0)
 122         {
 123                 *khz = 0;
 124         }
 125         else
 126         {
 127                 *khz = 64000/speed;
 128         }
 129
 130         return ERROR_OK;
 131 }
 132
 133 static int dummy_speed(int speed)
 134 {
 135         return ERROR_OK;
 136 }
 137
 138 static int dummy_init(void)
 139 {
 140         bitbang_interface = &dummy_bitbang;
 141
 142         return ERROR_OK;
 143 }
 144
 145 static int dummy_quit(void)
 146 {
 147         return ERROR_OK;
 148 }
 149
 150 static const struct command_registration dummy_command_handlers[] = {
 151         {
 152                 .name = "dummy",
 153                 .mode = COMMAND_ANY,
 154                 .help = "dummy interface driver commands",
 155
 156                 .chain = hello_command_handlers,
 157         },
 158         COMMAND_REGISTRATION_DONE,
 159 };
 160
 161 /* The dummy driver is used to easily check the code path
 162  * where the target is unresponsive.
 163  */
 164 struct jtag_interface dummy_interface = {
 165                 .name = "dummy",
 166
 167                 .supported = DEBUG_CAP_TMS_SEQ,
 168                 .commands = dummy_command_handlers,
 169
 170                 .execute_queue = &bitbang_execute_queue,
 171
 172                 .speed = &dummy_speed,
 173                 .khz = &dummy_khz,
 174                 .speed_div = &dummy_speed_div,
 175
 176                 .init = &dummy_init,
 177                 .quit = &dummy_quit,
 178         };