1 /***************************************************************************
2 * Copyright (C) 2008 by Øyvind Harboe *
3 * oyvind.harboe@zylin.com *
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. *
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. *
15 * You should have received a copy of the GNU General Public License *
16 * along with this program. If not, see <http://www.gnu.org/licenses/>. *
17 ***************************************************************************/
23 #include <jtag/interface.h>
27 /* my private tap controller state, which tracks state for calling code */
28 static tap_state_t dummy_state = TAP_RESET;
30 static int dummy_clock; /* edge detector */
32 static int clock_count; /* count clocks in any stable state, only stable states */
34 static uint32_t dummy_data;
36 static bb_value_t dummy_read(void)
38 int data = 1 & dummy_data;
39 dummy_data = (dummy_data >> 1) | (1 << 31);
40 return data ? BB_HIGH : BB_LOW;
43 static int dummy_write(int tck, int tms, int tdi)
45 /* TAP standard: "state transitions occur on rising edge of clock" */
46 if (tck != dummy_clock) {
48 tap_state_t old_state = dummy_state;
49 dummy_state = tap_state_transition(old_state, tms);
51 if (old_state != dummy_state) {
53 LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
57 LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));
60 if (dummy_state == TAP_DRCAPTURE)
61 dummy_data = 0x01255043;
64 /* this is a stable state clock edge, no change of state here,
65 * simply increment clock_count for subsequent logging
75 static int dummy_reset(int trst, int srst)
79 if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
80 dummy_state = TAP_RESET;
82 LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
86 static int dummy_led(int on)
91 static struct bitbang_interface dummy_bitbang = {
93 .write = &dummy_write,
94 .reset = &dummy_reset,
98 static int dummy_khz(int khz, int *jtag_speed)
103 *jtag_speed = 64000/khz;
107 static int dummy_speed_div(int speed, int *khz)
117 static int dummy_speed(int speed)
122 static int dummy_init(void)
124 bitbang_interface = &dummy_bitbang;
129 static int dummy_quit(void)
134 static const struct command_registration dummy_command_handlers[] = {
138 .help = "dummy interface driver commands",
140 .chain = hello_command_handlers,
142 COMMAND_REGISTRATION_DONE,
145 /* The dummy driver is used to easily check the code path
146 * where the target is unresponsive.
148 struct jtag_interface dummy_interface = {
151 .supported = DEBUG_CAP_TMS_SEQ,
152 .commands = dummy_command_handlers,
153 .transports = jtag_only,
155 .execute_queue = &bitbang_execute_queue,
157 .speed = &dummy_speed,
159 .speed_div = &dummy_speed_div,