openocd/src/jtag/drivers/buspirate.c

/***************************************************************************
 *   Copyright (C) 2010 by Michal Demin                                    *
 *   based on usbprog.c and arm-jtag-ew.c                                  *
 *                                                                         *
 *   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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

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

#include <jtag/interface.h>
#include <jtag/commands.h>

#include <termios.h>
#include <fcntl.h>
#include <sys/ioctl.h>

#undef DEBUG_SERIAL
/*#define DEBUG_SERIAL */
static int buspirate_execute_queue(void);
static int buspirate_speed(int speed);
static int buspirate_khz(int khz, int *jtag_speed);
static int buspirate_init(void);
static int buspirate_quit(void);

static void buspirate_end_state(tap_state_t state);
static void buspirate_state_move(void);
static void buspirate_path_move(int num_states, tap_state_t *path);
static void buspirate_runtest(int num_cycles);
static void buspirate_scan(bool ir_scan, enum scan_type type,
	uint8_t *buffer, int scan_size, struct scan_command *command);

#define CMD_UNKNOWN       0x00
#define CMD_PORT_MODE     0x01
#define CMD_FEATURE       0x02
#define CMD_READ_ADCS     0x03
/*#define CMD_TAP_SHIFT     0x04 // old protocol */
#define CMD_TAP_SHIFT     0x05
#define CMD_ENTER_OOCD    0x06
#define CMD_UART_SPEED    0x07
#define CMD_JTAG_SPEED    0x08

/* Not all OSes have this speed defined */
#if !defined(B1000000)
#define  B1000000 0010010
#endif

enum {
	MODE_HIZ = 0,
	MODE_JTAG = 1,		/* push-pull outputs */
	MODE_JTAG_OD = 2,	/* open-drain outputs */
};

enum {
	FEATURE_LED = 0x01,
	FEATURE_VREG = 0x02,
	FEATURE_TRST = 0x04,
	FEATURE_SRST = 0x08,
	FEATURE_PULLUP = 0x10
};

enum {
	ACTION_DISABLE = 0,
	ACTION_ENABLE = 1
};

enum {
	SERIAL_NORMAL = 0,
	SERIAL_FAST = 1
};

static int buspirate_fd = -1;
static int buspirate_pinmode = MODE_JTAG_OD;
static int buspirate_baudrate = SERIAL_NORMAL;
static int buspirate_vreg;
static int buspirate_pullup;
static char *buspirate_port;

/* TAP interface */
static void buspirate_tap_init(void);
static int buspirate_tap_execute(void);
static void buspirate_tap_append(int tms, int tdi);
static void buspirate_tap_append_scan(int length, uint8_t *buffer,
		struct scan_command *command);
static void buspirate_tap_make_space(int scan, int bits);

static void buspirate_reset(int trst, int srst);

/* low level interface */
static void buspirate_jtag_reset(int);
static void buspirate_jtag_enable(int);
static unsigned char buspirate_jtag_command(int, char *, int);
static void buspirate_jtag_set_speed(int, char);
static void buspirate_jtag_set_mode(int, char);
static void buspirate_jtag_set_feature(int, char, char);
static void buspirate_jtag_get_adcs(int);

/* low level HW communication interface */
static int buspirate_serial_open(char *port);
static int buspirate_serial_setspeed(int fd, char speed);
static int buspirate_serial_write(int fd, char *buf, int size);
static int buspirate_serial_read(int fd, char *buf, int size);
static void buspirate_serial_close(int fd);
static void buspirate_print_buffer(char *buf, int size);

static int buspirate_speed(int speed)
{
	/* TODO */
	LOG_INFO("Want to set speed to %dkHz, but not implemented yet", speed);
	return ERROR_OK;
}

static int buspirate_khz(int khz, int *jtag_speed)
{
	*jtag_speed = khz;
	return ERROR_OK;
}

static int buspirate_execute_queue(void)
{
	/* currently processed command */
	struct jtag_command *cmd = jtag_command_queue;
	int scan_size;
	enum scan_type type;
	uint8_t *buffer;

	while (cmd) {
		switch (cmd->type) {
		case JTAG_RUNTEST:
			DEBUG_JTAG_IO("runtest %i cycles, end in %s",
				cmd->cmd.runtest->num_cycles,
				tap_state_name(cmd->cmd.runtest
					->end_state));
			buspirate_end_state(cmd->cmd.runtest
					->end_state);
			buspirate_runtest(cmd->cmd.runtest
					->num_cycles);
			break;
		case JTAG_TLR_RESET:
			DEBUG_JTAG_IO("statemove end in %s",
				tap_state_name(cmd->cmd.statemove
						->end_state));
			buspirate_end_state(cmd->cmd.statemove
					->end_state);
			buspirate_state_move();
			break;
		case JTAG_PATHMOVE:
			DEBUG_JTAG_IO("pathmove: %i states, end in %s",
				cmd->cmd.pathmove->num_states,
				tap_state_name(cmd->cmd.pathmove
					->path[cmd->cmd.pathmove
						->num_states - 1]));
			buspirate_path_move(cmd->cmd.pathmove
					->num_states,
					cmd->cmd.pathmove->path);
			break;
		case JTAG_SCAN:
			DEBUG_JTAG_IO("scan end in %s",
				tap_state_name(cmd->cmd.scan
					->end_state));

			buspirate_end_state(cmd->cmd.scan
					->end_state);

			scan_size = jtag_build_buffer(cmd->cmd.scan,
					&buffer);
			type = jtag_scan_type(cmd->cmd.scan);
			buspirate_scan(cmd->cmd.scan->ir_scan, type,
				buffer, scan_size, cmd->cmd.scan);

			break;
		case JTAG_RESET:
			DEBUG_JTAG_IO("reset trst: %i srst %i",
				cmd->cmd.reset->trst, cmd->cmd.reset->srst);

			/* flush buffers, so we can reset */
			buspirate_tap_execute();

			if (cmd->cmd.reset->trst == 1)
				tap_set_state(TAP_RESET);
			buspirate_reset(cmd->cmd.reset->trst,
					cmd->cmd.reset->srst);
			break;
		case JTAG_SLEEP:
			DEBUG_JTAG_IO("sleep %i", cmd->cmd.sleep->us);
			buspirate_tap_execute();
			jtag_sleep(cmd->cmd.sleep->us);
				break;
		default:
			LOG_ERROR("BUG: unknown JTAG command type encountered");
			exit(-1);
		}

		cmd = cmd->next;
	}

	return buspirate_tap_execute();
}

static int buspirate_init(void)
{
	if (buspirate_port == NULL) {
		LOG_ERROR("You need to specify the serial port!");
		return ERROR_JTAG_INIT_FAILED;
	}

	buspirate_fd = buspirate_serial_open(buspirate_port);
	if (buspirate_fd == -1) {
		LOG_ERROR("Could not open serial port");
		return ERROR_JTAG_INIT_FAILED;
	}

	buspirate_serial_setspeed(buspirate_fd, SERIAL_NORMAL);

	buspirate_jtag_enable(buspirate_fd);

	if (buspirate_baudrate != SERIAL_NORMAL)
		buspirate_jtag_set_speed(buspirate_fd, SERIAL_FAST);

	LOG_INFO("Buspirate Interface ready!");

	buspirate_tap_init();
	buspirate_jtag_set_mode(buspirate_fd, buspirate_pinmode);
	buspirate_jtag_set_feature(buspirate_fd, FEATURE_VREG,
		(buspirate_vreg == 1) ? ACTION_ENABLE : ACTION_DISABLE);
	buspirate_jtag_set_feature(buspirate_fd, FEATURE_PULLUP,
		(buspirate_pullup == 1) ? ACTION_ENABLE : ACTION_DISABLE);
	buspirate_reset(0, 0);

	return ERROR_OK;
}

static int buspirate_quit(void)
{
	LOG_INFO("Shutting down buspirate.");
	buspirate_jtag_set_mode(buspirate_fd, MODE_HIZ);

	buspirate_jtag_set_speed(buspirate_fd, SERIAL_NORMAL);
	buspirate_jtag_reset(buspirate_fd);

	buspirate_serial_close(buspirate_fd);

	if (buspirate_port) {
		free(buspirate_port);
		buspirate_port = NULL;
	}
	return ERROR_OK;
}

/* openocd command interface */
COMMAND_HANDLER(buspirate_handle_adc_command)
{
	if (buspirate_fd == -1)
		return ERROR_OK;

	/* send the command */
	buspirate_jtag_get_adcs(buspirate_fd);

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_vreg_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (atoi(CMD_ARGV[0]) == 1)
		buspirate_vreg = 1;
	else if (atoi(CMD_ARGV[0]) == 0)
		buspirate_vreg = 0;
	else
		LOG_ERROR("usage: buspirate_vreg <1|0>");

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_pullup_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (atoi(CMD_ARGV[0]) == 1)
		buspirate_pullup = 1;
	else if (atoi(CMD_ARGV[0]) == 0)
		buspirate_pullup = 0;
	else
		LOG_ERROR("usage: buspirate_pullup <1|0>");

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_led_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (atoi(CMD_ARGV[0]) == 1) {
		/* enable led */
		buspirate_jtag_set_feature(buspirate_fd, FEATURE_LED,
				ACTION_ENABLE);
	} else if (atoi(CMD_ARGV[0]) == 0) {
		/* disable led */
		buspirate_jtag_set_feature(buspirate_fd, FEATURE_LED,
				ACTION_DISABLE);
	} else {
		LOG_ERROR("usage: buspirate_led <1|0>");
	}

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_mode_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (CMD_ARGV[0][0] == 'n')
		buspirate_pinmode = MODE_JTAG;
	else if (CMD_ARGV[0][0] == 'o')
		buspirate_pinmode = MODE_JTAG_OD;
	else
		LOG_ERROR("usage: buspirate_mode <normal|open-drain>");

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_speed_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (CMD_ARGV[0][0] == 'n')
		buspirate_baudrate = SERIAL_NORMAL;
	else if (CMD_ARGV[0][0] == 'f')
		buspirate_baudrate = SERIAL_FAST;
	else
		LOG_ERROR("usage: buspirate_speed <normal|fast>");

	return ERROR_OK;

}

COMMAND_HANDLER(buspirate_handle_port_command)
{
	if (CMD_ARGC < 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	if (buspirate_port == NULL)
		buspirate_port = strdup(CMD_ARGV[0]);

	return ERROR_OK;

}

static const struct command_registration buspirate_command_handlers[] = {
	{
		.name = "buspirate_adc",
		.handler = &buspirate_handle_adc_command,
		.mode = COMMAND_EXEC,
		.help = "reads voltages on adc pins",
	},
	{
		.name = "buspirate_vreg",
		.usage = "<1|0>",
		.handler = &buspirate_handle_vreg_command,
		.mode = COMMAND_CONFIG,
		.help = "changes the state of voltage regulators",
	},
	{
		.name = "buspirate_pullup",
		.usage = "<1|0>",
		.handler = &buspirate_handle_pullup_command,
		.mode = COMMAND_CONFIG,
		.help = "changes the state of pullup",
	},
	{
		.name = "buspirate_led",
		.usage = "<1|0>",
		.handler = &buspirate_handle_led_command,
		.mode = COMMAND_EXEC,
		.help = "changes the state of led",
	},
	{
		.name = "buspirate_speed",
		.usage = "<normal|fast>",
		.handler = &buspirate_handle_speed_command,
		.mode = COMMAND_CONFIG,
		.help = "speed of the interface",
	},
	{
		.name = "buspirate_mode",
		.usage = "<normal|open-drain>",
		.handler = &buspirate_handle_mode_command,
		.mode = COMMAND_CONFIG,
		.help = "pin mode of the interface",
	},
	{
		.name = "buspirate_port",
		.usage = "/dev/ttyUSB0",
		.handler = &buspirate_handle_port_command,
		.mode =	COMMAND_CONFIG,
		.help = "name of the serial port to open",
	},
	COMMAND_REGISTRATION_DONE
};

struct jtag_interface buspirate_interface = {
	.name = "buspirate",
	.execute_queue = buspirate_execute_queue,
	.speed = buspirate_speed,
	.khz = buspirate_khz,
	.commands = buspirate_command_handlers,
	.init = buspirate_init,
	.quit = buspirate_quit
};

/*************** jtag execute commands **********************/
static void buspirate_end_state(tap_state_t state)
{
	if (tap_is_state_stable(state))
		tap_set_end_state(state);
	else {
		LOG_ERROR("BUG: %i is not a valid end state", state);
		exit(-1);
	}
}

static void buspirate_state_move(void)
{
	int i = 0, tms = 0;
	uint8_t tms_scan = tap_get_tms_path(tap_get_state(),
			tap_get_end_state());
	int tms_count = tap_get_tms_path_len(tap_get_state(),
			tap_get_end_state());

	for (i = 0; i < tms_count; i++) {
		tms = (tms_scan >> i) & 1;
		buspirate_tap_append(tms, 0);
	}

	tap_set_state(tap_get_end_state());
}

static void buspirate_path_move(int num_states, tap_state_t *path)
{
	int i;

	for (i = 0; i < num_states; i++) {
		if (tap_state_transition(tap_get_state(), false) == path[i]) {
			buspirate_tap_append(0, 0);
		} else if (tap_state_transition(tap_get_state(), true)
				== path[i]) {
			buspirate_tap_append(1, 0);
		} else {
			LOG_ERROR("BUG: %s -> %s isn't a valid "
				"TAP transition",
				tap_state_name(tap_get_state()),
				tap_state_name(path[i]));
			exit(-1);
		}

		tap_set_state(path[i]);
	}

	tap_set_end_state(tap_get_state());
}

static void buspirate_runtest(int num_cycles)
{
	int i;

	tap_state_t saved_end_state = tap_get_end_state();

	/* only do a state_move when we're not already in IDLE */
	if (tap_get_state() != TAP_IDLE) {
		buspirate_end_state(TAP_IDLE);
		buspirate_state_move();
	}

	for (i = 0; i < num_cycles; i++)
		buspirate_tap_append(0, 0);

	DEBUG_JTAG_IO("runtest: cur_state %s end_state %s",
			tap_state_name(tap_get_state()),
			tap_state_name(tap_get_end_state()));

	/* finish in end_state */
	buspirate_end_state(saved_end_state);
	if (tap_get_state() != tap_get_end_state())
		buspirate_state_move();
}

static void buspirate_scan(bool ir_scan, enum scan_type type,
	uint8_t *buffer, int scan_size, struct scan_command *command)
{
	tap_state_t saved_end_state;

	buspirate_tap_make_space(1, scan_size+8);
	/* is 8 correct ? (2 moves = 16) */

	saved_end_state = tap_get_end_state();

	buspirate_end_state(ir_scan ? TAP_IRSHIFT : TAP_DRSHIFT);
	buspirate_state_move();

	buspirate_tap_append_scan(scan_size, buffer, command);

	/* move to PAUSE */
	buspirate_tap_append(0, 0);

	/* restore the saved state */
	buspirate_end_state(saved_end_state);
	tap_set_state(ir_scan ? TAP_IRPAUSE : TAP_DRPAUSE);

	if (tap_get_state() != tap_get_end_state())
		buspirate_state_move();
}


/************************* TAP related stuff **********/

#define BUSPIRATE_BUFFER_SIZE 1024
#define BUSPIRATE_MAX_PENDING_SCANS 32

static char tms_chain[BUSPIRATE_BUFFER_SIZE]; /* send */
static char tdi_chain[BUSPIRATE_BUFFER_SIZE]; /* send */
static int tap_chain_index;

struct pending_scan_result /* this was stolen from arm-jtag-ew */
{
	int first; /* First bit position in tdo_buffer to read */
	int length; /* Number of bits to read */
	struct scan_command *command; /* Corresponding scan command */
	uint8_t *buffer;
};

static struct pending_scan_result
tap_pending_scans[BUSPIRATE_MAX_PENDING_SCANS];
static int tap_pending_scans_num;

static void buspirate_tap_init(void)
{
	tap_chain_index = 0;
	tap_pending_scans_num = 0;
}

static int buspirate_tap_execute(void)
{
	char tmp[4096];
	uint8_t *in_buf;
	int i;
	int fill_index = 0;
	int ret;
	int bytes_to_send;

	if (tap_chain_index <= 0)
		return ERROR_OK;

	LOG_DEBUG("executing tap num bits = %i scans = %i",
			tap_chain_index, tap_pending_scans_num);

	bytes_to_send = (tap_chain_index+7) / 8;

	tmp[0] = CMD_TAP_SHIFT; /* this command expects number of bits */
	tmp[1] = (char)(tap_chain_index >> 8);  /* high */
	tmp[2] = (char)(tap_chain_index);  /* low */

	fill_index = 3;
	for (i = 0; i < bytes_to_send; i++) {
		tmp[fill_index] = tdi_chain[i];
		fill_index++;
		tmp[fill_index] = tms_chain[i];
		fill_index++;
	}

	ret = buspirate_serial_write(buspirate_fd, tmp, 3 + bytes_to_send*2);
	if (ret != bytes_to_send*2+3) {
		LOG_ERROR("error writing :(");
		return ERROR_JTAG_DEVICE_ERROR;
	}

	ret = buspirate_serial_read(buspirate_fd, tmp, bytes_to_send + 3);
	if (ret != bytes_to_send + 3) {
		LOG_ERROR("error reading");
		return ERROR_FAIL;
	}
	in_buf = (uint8_t *)(&tmp[3]);

	/* parse the scans */
	for (i = 0; i < tap_pending_scans_num; i++) {
		uint8_t *buffer = tap_pending_scans[i].buffer;
		int length = tap_pending_scans[i].length;
		int first = tap_pending_scans[i].first;
		struct scan_command *command = tap_pending_scans[i].command;

		/* copy bits from buffer */
		buf_set_buf(in_buf, first, buffer, 0, length);

		/* return buffer to higher level */
		if (jtag_read_buffer(buffer, command) != ERROR_OK) {
			buspirate_tap_init();
			return ERROR_JTAG_QUEUE_FAILED;
		}

		free(buffer);
	}
	tap_pending_scans_num = 0;
	tap_chain_index = 0;
	return ERROR_OK;
}

static void buspirate_tap_make_space(int scans, int bits)
{
	int have_scans = BUSPIRATE_MAX_PENDING_SCANS - tap_pending_scans_num;
	int have_bits = BUSPIRATE_BUFFER_SIZE * 8 - tap_chain_index;

	if ((have_scans < scans) || (have_bits < bits))
		buspirate_tap_execute();
}

static void buspirate_tap_append(int tms, int tdi)
{
	int chain_index;

	buspirate_tap_make_space(0, 1);
	chain_index = tap_chain_index / 8;

	if (chain_index < BUSPIRATE_BUFFER_SIZE) {
		int bit_index = tap_chain_index % 8;
		uint8_t bit = 1 << bit_index;

		if (tms)
			tms_chain[chain_index] |= bit;
		else
			tms_chain[chain_index] &= ~bit;

		if (tdi)
			tdi_chain[chain_index] |= bit;
		else
			tdi_chain[chain_index] &= ~bit;

		tap_chain_index++;
	} else
		LOG_ERROR("tap_chain overflow, bad things will happen");

}

static void buspirate_tap_append_scan(int length, uint8_t *buffer,
		struct scan_command *command)
{
	int i;
	tap_pending_scans[tap_pending_scans_num].length = length;
	tap_pending_scans[tap_pending_scans_num].buffer = buffer;
	tap_pending_scans[tap_pending_scans_num].command = command;
	tap_pending_scans[tap_pending_scans_num].first = tap_chain_index;

	for (i = 0; i < length; i++) {
		int tms = (i < length-1 ? 0 : 1);
		int tdi = (buffer[i/8] >> (i%8)) & 1;
		buspirate_tap_append(tms, tdi);
	}
	tap_pending_scans_num++;
}

/*************** jtag wrapper functions *********************/

/* (1) assert or (0) deassert reset lines */
static void buspirate_reset(int trst, int srst)
{
	LOG_DEBUG("trst: %i, srst: %i", trst, srst);

	if (trst)
		buspirate_jtag_set_feature(buspirate_fd,
				FEATURE_TRST, ACTION_DISABLE);
	else
		buspirate_jtag_set_feature(buspirate_fd,
				FEATURE_TRST, ACTION_ENABLE);

	if (srst)
		buspirate_jtag_set_feature(buspirate_fd,
				FEATURE_SRST, ACTION_DISABLE);
	else
		buspirate_jtag_set_feature(buspirate_fd,
				FEATURE_SRST, ACTION_ENABLE);
}

/*************** jtag lowlevel functions ********************/
static void buspirate_jtag_enable(int fd)
{
	int ret;
	char tmp[21] = { [0 ... 20] = 0x00 };
	int done = 0;
	int cmd_sent = 0;

	LOG_DEBUG("Entering binary mode");
	buspirate_serial_write(fd, tmp, 20);
	usleep(10000);

	/* reads 1 to n "BBIO1"s and one "OCD1" */
	while (!done) {
		ret = buspirate_serial_read(fd, tmp, 4);
		if (ret != 4) {
			LOG_ERROR("Buspirate error. Is binary"
				"/OpenOCD support enabled?");
			exit(-1);
		}
		if (strncmp(tmp, "BBIO", 4) == 0) {
			ret = buspirate_serial_read(fd, tmp, 1);
			if (ret != 1) {
				LOG_ERROR("Buspirate did not answer correctly! "
					"Do you have correct firmware?");
				exit(-1);
			}
			if (tmp[0] != '1') {
				LOG_ERROR("Unsupported binary protocol");
				exit(-1);
			}
			if (cmd_sent == 0) {
				cmd_sent = 1;
				tmp[0] = CMD_ENTER_OOCD;
				ret = buspirate_serial_write(fd, tmp, 1);
				if (ret != 1) {
					LOG_ERROR("error reading");
					exit(-1);
				}
			}
		} else if (strncmp(tmp, "OCD1", 4) == 0)
			done = 1;
		else {
			LOG_ERROR("Buspirate did not answer correctly! "
				"Do you have correct firmware?");
			exit(-1);
		}
	}

}

static void buspirate_jtag_reset(int fd)
{
	char tmp[5];

	tmp[0] = 0x00; /* exit OCD1 mode */
	buspirate_serial_write(fd, tmp, 1);
	usleep(10000);
	/* We ignore the return value here purposly, nothing we can do */
	buspirate_serial_read(fd, tmp, 5);
	if (strncmp(tmp, "BBIO1", 5) == 0) {
		tmp[0] = 0x0F; /*  reset BP */
		buspirate_serial_write(fd, tmp, 1);
	} else
		LOG_ERROR("Unable to restart buspirate!");
}

static void buspirate_jtag_set_speed(int fd, char speed)
{
	int ret;
	char tmp[2];
	char ack[2];

	ack[0] = 0xAA;
	ack[1] = 0x55;

	tmp[0] = CMD_UART_SPEED;
	tmp[1] = speed;
	buspirate_jtag_command(fd, tmp, 2);

	/* here the adapter changes speed, we need follow */
	buspirate_serial_setspeed(fd, speed);

	buspirate_serial_write(fd, ack, 2);
	ret = buspirate_serial_read(fd, tmp, 2);
	if (ret != 2) {
		LOG_ERROR("Buspirate did not ack speed change");
		exit(-1);
	}
	if ((tmp[0] != CMD_UART_SPEED) || (tmp[1] != speed)) {
		LOG_ERROR("Buspirate did not reply as expected");
		exit(-1);
	}
	LOG_INFO("Buspirate switched to %s mode",
		(speed == SERIAL_NORMAL) ? "normal" : "FAST");
}


static void buspirate_jtag_set_mode(int fd, char mode)
{
	char tmp[2];
	tmp[0] = CMD_PORT_MODE;
	tmp[1] = mode;
	buspirate_jtag_command(fd, tmp, 2);
}

static void buspirate_jtag_set_feature(int fd, char feat, char action)
{
	char tmp[3];
	tmp[0] = CMD_FEATURE;
	tmp[1] = feat;   /* what */
	tmp[2] = action; /* action */
	buspirate_jtag_command(fd, tmp, 3);
}

static void buspirate_jtag_get_adcs(int fd)
{
	uint8_t tmp[10];
	uint16_t a, b, c, d;
	tmp[0] = CMD_READ_ADCS;
	buspirate_jtag_command(fd, (char *)tmp, 1);
	a = tmp[2] << 8 | tmp[3];
	b = tmp[4] << 8 | tmp[5];
	c = tmp[6] << 8 | tmp[7];
	d = tmp[8] << 8 | tmp[9];

	LOG_INFO("ADC: ADC_Pin = %.02f VPullup = %.02f V33 = %.02f "
		"V50 = %.02f",
		((float)a)/155.1515, ((float)b)/155.1515,
		((float)c)/155.1515, ((float)d)/155.1515);
}

static unsigned char buspirate_jtag_command(int fd,
		char *cmd, int cmdlen)
{
	int res;
	int len = 0;

	res = buspirate_serial_write(fd, cmd, cmdlen);

	if ((cmd[0] == CMD_UART_SPEED)
				|| (cmd[0] == CMD_PORT_MODE)
				|| (cmd[0] == CMD_FEATURE)
				|| (cmd[0] == CMD_JTAG_SPEED))
		return 1;

	if (res == cmdlen) {
		switch (cmd[0]) {
		case CMD_READ_ADCS:
			len = 10; /* 2*sizeof(char)+4*sizeof(uint16_t) */
			break;
		case CMD_TAP_SHIFT:
			len = cmdlen;
			break;
		default:
			LOG_INFO("Wrong !");
		}
		res =  buspirate_serial_read(fd, cmd, len);
		if (res > 0)
			return (unsigned char)cmd[1];
		else
			return -1;
	} else
		return -1;
	return 0;
}

/* low level serial port */
/* TODO add support for WIN32 and others ! */
static int buspirate_serial_open(char *port)
{
	int fd;
	fd = open(buspirate_port, O_RDWR | O_NOCTTY | O_NDELAY);
	return fd;
}

static int buspirate_serial_setspeed(int fd, char speed)
{
	struct termios t_opt;
	speed_t baud = (speed == SERIAL_FAST) ? B1000000 : B115200;

	/* set the serial port parameters */
	fcntl(fd, F_SETFL, 0);
	tcgetattr(fd, &t_opt);
	cfsetispeed(&t_opt, baud);
	cfsetospeed(&t_opt, baud);
	t_opt.c_cflag |= (CLOCAL | CREAD);
	t_opt.c_cflag &= ~PARENB;
	t_opt.c_cflag &= ~CSTOPB;
	t_opt.c_cflag &= ~CSIZE;
	t_opt.c_cflag |= CS8;
	t_opt.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
	t_opt.c_iflag &= ~(IXON | IXOFF | IXANY);
	t_opt.c_oflag &= ~OPOST;
	t_opt.c_cc[VMIN] = 0;
	t_opt.c_cc[VTIME] = 10;
	tcflush(fd, TCIFLUSH);
	tcsetattr(fd, TCSANOW, &t_opt);

	return 0;
}

static int buspirate_serial_write(int fd, char *buf, int size)
{
	int ret = 0;

	ret = write(fd, buf, size);

	LOG_DEBUG("size = %d ret = %d", size, ret);
	buspirate_print_buffer(buf, size);

	if (ret != size)
		LOG_ERROR("Error sending data");

	return ret;
}

static int buspirate_serial_read(int fd, char *buf, int size)
{
	int len = 0;
	int ret = 0;
	int timeout = 0;

	while (len < size) {
		ret = read(fd, buf+len, size-len);
		if (ret == -1)
			return -1;

		if (ret == 0) {
			timeout++;

			if (timeout >= 10)
				break;

			continue;
		}

		len += ret;
	}

	LOG_DEBUG("should have read = %d actual size = %d", size, len);
	buspirate_print_buffer(buf, len);

	if (len != size)
		LOG_ERROR("Error reading data");

	return len;
}

static void buspirate_serial_close(int fd)
{
	close(fd);
}

#define LINE_SIZE      81
#define BYTES_PER_LINE 16
static void buspirate_print_buffer(char *buf, int size)
{
	char line[LINE_SIZE];
	char tmp[10];
	int offset = 0;

	line[0] = 0;
	while (offset < size) {
		snprintf(tmp, 5, "%02x ", (uint8_t)buf[offset]);
		offset++;

		strcat(line, tmp);

		if (offset % BYTES_PER_LINE == 0) {
			LOG_DEBUG("%s", line);
			line[0] = 0;
		}
	}

	if (line[0] != 0)
		LOG_DEBUG("%s", line);
}