src/jtag/drivers/dummy.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 /***************************************************************************
   4  *   Copyright (C) 2008 by Øyvind Harboe                                   *
   5  *   oyvind.harboe@zylin.com                                               *
   6  ***************************************************************************/
   7
   8 #ifdef HAVE_CONFIG_H
   9 #include "config.h"
  10 #endif
  11
  12 #include <jtag/interface.h>
  13 #include "bitbang.h"
  14 #include "hello.h"
  15
  16 /* my private tap controller state, which tracks state for calling code */
  17 static tap_state_t dummy_state = TAP_RESET;
  18
  19 static int dummy_clock;         /* edge detector */
  20
  21 static int clock_count;         /* count clocks in any stable state, only stable states */
  22
  23 static uint32_t dummy_data;
  24
  25 static bb_value_t dummy_read(void)
  26 {
  27         int data = 1 & dummy_data;
  28         dummy_data = (dummy_data >> 1) | (1 << 31);
  29         return data ? BB_HIGH : BB_LOW;
  30 }
  31
  32 static int dummy_write(int tck, int tms, int tdi)
  33 {
  34         /* TAP standard: "state transitions occur on rising edge of clock" */
  35         if (tck != dummy_clock) {
  36                 if (tck) {
  37                         tap_state_t old_state = dummy_state;
  38                         dummy_state = tap_state_transition(old_state, tms);
  39
  40                         if (old_state != dummy_state) {
  41                                 if (clock_count) {
  42                                         LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
  43                                         clock_count = 0;
  44                                 }
  45
  46                                 LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));
  47
  48 #if defined(DEBUG)
  49                                 if (dummy_state == TAP_DRCAPTURE)
  50                                         dummy_data = 0x01255043;
  51 #endif
  52                         } else {
  53                                 /* this is a stable state clock edge, no change of state here,
  54                                  * simply increment clock_count for subsequent logging
  55                                  */
  56                                 ++clock_count;
  57                         }
  58                 }
  59                 dummy_clock = tck;
  60         }
  61         return ERROR_OK;
  62 }
  63
  64 static int dummy_reset(int trst, int srst)
  65 {
  66         dummy_clock = 0;
  67
  68         if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
  69                 dummy_state = TAP_RESET;
  70
  71         LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
  72         return ERROR_OK;
  73 }
  74
  75 static int dummy_led(int on)
  76 {
  77         return ERROR_OK;
  78 }
  79
  80 static struct bitbang_interface dummy_bitbang = {
  81                 .read = &dummy_read,
  82                 .write = &dummy_write,
  83                 .blink = &dummy_led,
  84         };
  85
  86 static int dummy_khz(int khz, int *jtag_speed)
  87 {
  88         if (khz == 0)
  89                 *jtag_speed = 0;
  90         else
  91                 *jtag_speed = 64000/khz;
  92         return ERROR_OK;
  93 }
  94
  95 static int dummy_speed_div(int speed, int *khz)
  96 {
  97         if (speed == 0)
  98                 *khz = 0;
  99         else
 100                 *khz = 64000/speed;
 101
 102         return ERROR_OK;
 103 }
 104
 105 static int dummy_speed(int speed)
 106 {
 107         return ERROR_OK;
 108 }
 109
 110 static int dummy_init(void)
 111 {
 112         bitbang_interface = &dummy_bitbang;
 113
 114         return ERROR_OK;
 115 }
 116
 117 static int dummy_quit(void)
 118 {
 119         return ERROR_OK;
 120 }
 121
 122 static const struct command_registration dummy_command_handlers[] = {
 123         {
 124                 .name = "dummy",
 125                 .mode = COMMAND_ANY,
 126                 .help = "dummy interface driver commands",
 127                 .chain = hello_command_handlers,
 128                 .usage = "",
 129         },
 130         COMMAND_REGISTRATION_DONE,
 131 };
 132
 133 /* The dummy driver is used to easily check the code path
 134  * where the target is unresponsive.
 135  */
 136 static struct jtag_interface dummy_interface = {
 137         .supported = DEBUG_CAP_TMS_SEQ,
 138         .execute_queue = &bitbang_execute_queue,
 139 };
 140
 141 struct adapter_driver dummy_adapter_driver = {
 142         .name = "dummy",
 143         .transports = jtag_only,
 144         .commands = dummy_command_handlers,
 145
 146         .init = &dummy_init,
 147         .quit = &dummy_quit,
 148         .reset = &dummy_reset,
 149         .speed = &dummy_speed,
 150         .khz = &dummy_khz,
 151         .speed_div = &dummy_speed_div,
 152
 153         .jtag_ops = &dummy_interface,
 154 };