openocd/src/jtag/drivers/dummy.c

/***************************************************************************
 *   Copyright (C) 2008 by Øyvind Harboe                                   *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <jtag/interface.h>
#include "bitbang.h"
#include "hello.h"

/* my private tap controller state, which tracks state for calling code */
static tap_state_t dummy_state = TAP_RESET;

static int dummy_clock;		/* edge detector */

static int clock_count;		/* count clocks in any stable state, only stable states */

static uint32_t dummy_data;

static int dummy_read(void)
{
	int data = 1 & dummy_data;
	dummy_data = (dummy_data >> 1) | (1 << 31);
	return data;
}

static void dummy_write(int tck, int tms, int tdi)
{
	/* TAP standard: "state transitions occur on rising edge of clock" */
	if (tck != dummy_clock) {
		if (tck) {
			tap_state_t old_state = dummy_state;
			dummy_state = tap_state_transition(old_state, tms);

			if (old_state != dummy_state) {
				if (clock_count) {
					LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
					clock_count = 0;
				}

				LOG_DEBUG("dummy_tap: %s", tap_state_name(dummy_state));

#if defined(DEBUG)
				if (dummy_state == TAP_DRCAPTURE)
					dummy_data = 0x01255043;
#endif
			} else {
				/* this is a stable state clock edge, no change of state here,
				 * simply increment clock_count for subsequent logging
				 */
				++clock_count;
			}
		}
		dummy_clock = tck;
	}
}

static void dummy_reset(int trst, int srst)
{
	dummy_clock = 0;

	if (trst || (srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
		dummy_state = TAP_RESET;

	LOG_DEBUG("reset to: %s", tap_state_name(dummy_state));
}

static void dummy_led(int on)
{
}

static struct bitbang_interface dummy_bitbang = {
		.read = &dummy_read,
		.write = &dummy_write,
		.reset = &dummy_reset,
		.blink = &dummy_led,
	};

static int dummy_khz(int khz, int *jtag_speed)
{
	if (khz == 0)
		*jtag_speed = 0;
	else
		*jtag_speed = 64000/khz;
	return ERROR_OK;
}

static int dummy_speed_div(int speed, int *khz)
{
	if (speed == 0)
		*khz = 0;
	else
		*khz = 64000/speed;

	return ERROR_OK;
}

static int dummy_speed(int speed)
{
	return ERROR_OK;
}

static int dummy_init(void)
{
	bitbang_interface = &dummy_bitbang;

	return ERROR_OK;
}

static int dummy_quit(void)
{
	return ERROR_OK;
}

static const struct command_registration dummy_command_handlers[] = {
	{
		.name = "dummy",
		.mode = COMMAND_ANY,
		.help = "dummy interface driver commands",

		.chain = hello_command_handlers,
	},
	COMMAND_REGISTRATION_DONE,
};

/* The dummy driver is used to easily check the code path
 * where the target is unresponsive.
 */
struct jtag_interface dummy_interface = {
		.name = "dummy",

		.supported = DEBUG_CAP_TMS_SEQ,
		.commands = dummy_command_handlers,
		.transports = jtag_only,

		.execute_queue = &bitbang_execute_queue,

		.speed = &dummy_speed,
		.khz = &dummy_khz,
		.speed_div = &dummy_speed_div,

		.init = &dummy_init,
		.quit = &dummy_quit,
	};