dummy.c 4.13 KB
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/***************************************************************************
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 *   Copyright (C) 2008 by Øyvind Harboe                                   *
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 *   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     *
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 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
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 ***************************************************************************/
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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

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#include <jtag/interface.h>
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#include "bitbang.h"
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#include "hello.h"
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/* my private tap controller state, which tracks state for calling code */
static tap_state_t dummy_state = TAP_RESET;

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static int dummy_clock;		/* edge detector */
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static int clock_count;		/* count clocks in any stable state, only stable states */
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static uint32_t dummy_data;
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static bb_value_t dummy_read(void)
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{
	int data = 1 & dummy_data;
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	dummy_data = (dummy_data >> 1) | (1 << 31);
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	return data ? BB_HIGH : BB_LOW;
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}

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static int dummy_write(int tck, int tms, int tdi)
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{
	/* TAP standard: "state transitions occur on rising edge of clock" */
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	if (tck != dummy_clock) {
		if (tck) {
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			tap_state_t old_state = dummy_state;
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			dummy_state = tap_state_transition(old_state, tms);
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			if (old_state != dummy_state) {
				if (clock_count) {
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					LOG_DEBUG("dummy_tap: %d stable clocks", clock_count);
					clock_count = 0;
				}

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

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

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

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

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static int dummy_led(int on)
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{
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	return ERROR_OK;
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}

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

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

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

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static const struct command_registration dummy_command_handlers[] = {
	{
		.name = "dummy",
		.mode = COMMAND_ANY,
		.help = "dummy interface driver commands",
		.chain = hello_command_handlers,
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		.usage = "",
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	},
	COMMAND_REGISTRATION_DONE,
};

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

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		.supported = DEBUG_CAP_TMS_SEQ,
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		.commands = dummy_command_handlers,
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		.transports = jtag_only,
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		.execute_queue = &bitbang_execute_queue,

		.speed = &dummy_speed,
		.khz = &dummy_khz,
		.speed_div = &dummy_speed_div,
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		.init = &dummy_init,
		.quit = &dummy_quit,
	};