path: root/src/jtag/drivers/arm-jtag-ew.c

/***************************************************************************
 *   Copyright (C) 2009 by Dimitar Dimitrov <dinuxbg@gmail.com>            *
 *   based on Dominic Rath's and Benedikt Sauter's usbprog.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.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
 ***************************************************************************/

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

#include <jtag/interface.h>
#include <jtag/commands.h>
#include <usb.h>
#include "usb_common.h"

#define USB_VID						0x15ba
#define USB_PID						0x001e

#define ARMJTAGEW_EPT_BULK_OUT		0x01u
#define ARMJTAGEW_EPT_BULK_IN		0x82u

#define ARMJTAGEW_USB_TIMEOUT		2000

#define ARMJTAGEW_IN_BUFFER_SIZE	(4*1024)
#define ARMJTAGEW_OUT_BUFFER_SIZE	(4*1024)

/* USB command request codes. */
#define CMD_GET_VERSION				0x00
#define CMD_SELECT_DPIMPL			0x10
#define CMD_SET_TCK_FREQUENCY		0x11
#define CMD_GET_TCK_FREQUENCY		0x12
#define CMD_MEASURE_MAX_TCK_FREQ	0x15
#define CMD_MEASURE_RTCK_RESPONSE	0x16
#define CMD_TAP_SHIFT				0x17
#define CMD_SET_TAPHW_STATE			0x20
#define CMD_GET_TAPHW_STATE			0x21
#define CMD_TGPWR_SETUP				0x22

/* Global USB buffers */
static uint8_t usb_in_buffer[ARMJTAGEW_IN_BUFFER_SIZE];
static uint8_t usb_out_buffer[ARMJTAGEW_OUT_BUFFER_SIZE];

/* Queue command functions */
static void armjtagew_end_state(tap_state_t state);
static void armjtagew_state_move(void);
static void armjtagew_path_move(int num_states, tap_state_t *path);
static void armjtagew_runtest(int num_cycles);
static void armjtagew_scan(bool ir_scan,
		enum scan_type type,
		uint8_t *buffer,
		int scan_size,
		struct scan_command *command);
static void armjtagew_reset(int trst, int srst);
/* static void armjtagew_simple_command(uint8_t command); */
static int armjtagew_get_status(void);

/* tap buffer functions */
static void armjtagew_tap_init(void);
static int armjtagew_tap_execute(void);
static void armjtagew_tap_ensure_space(int scans, int bits);
static void armjtagew_tap_append_step(int tms, int tdi);
static void armjtagew_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command);

/* ARM-JTAG-EW lowlevel functions */
struct armjtagew {
	struct usb_dev_handle *usb_handle;
};

static struct armjtagew *armjtagew_usb_open(void);
static void armjtagew_usb_close(struct armjtagew *armjtagew);
static int armjtagew_usb_message(struct armjtagew *armjtagew, int out_length, int in_length);
static int armjtagew_usb_write(struct armjtagew *armjtagew, int out_length);
static int armjtagew_usb_read(struct armjtagew *armjtagew, int exp_in_length);

/* helper functions */
static int armjtagew_get_version_info(void);

#ifdef _DEBUG_USB_COMMS_
static void armjtagew_debug_buffer(uint8_t *buffer, int length);
#endif

static struct armjtagew *armjtagew_handle;

/**************************************************************************
 * External interface implementation */

static int armjtagew_execute_queue(void)
{
	struct jtag_command *cmd = jtag_command_queue;
	int scan_size;
	enum scan_type type;
	uint8_t *buffer;

	while (cmd != NULL) {
		switch (cmd->type) {
			case JTAG_RUNTEST:
				DEBUG_JTAG_IO("runtest %i cycles, end in %i",
						cmd->cmd.runtest->num_cycles, \
						cmd->cmd.runtest->end_state);

				armjtagew_end_state(cmd->cmd.runtest->end_state);
				armjtagew_runtest(cmd->cmd.runtest->num_cycles);
				break;

			case JTAG_TLR_RESET:
				DEBUG_JTAG_IO("statemove end in %i", cmd->cmd.statemove->end_state);

				armjtagew_end_state(cmd->cmd.statemove->end_state);
				armjtagew_state_move();
				break;

			case JTAG_PATHMOVE:
				DEBUG_JTAG_IO("pathmove: %i states, end in %i", \
						cmd->cmd.pathmove->num_states, \
						cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]);

				armjtagew_path_move(cmd->cmd.pathmove->num_states,
						cmd->cmd.pathmove->path);
				break;

			case JTAG_SCAN:
				DEBUG_JTAG_IO("scan end in %i", cmd->cmd.scan->end_state);

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

				scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
				DEBUG_JTAG_IO("scan input, length = %d", scan_size);

#ifdef _DEBUG_USB_COMMS_
				armjtagew_debug_buffer(buffer, (scan_size + 7) / 8);
#endif
				type = jtag_scan_type(cmd->cmd.scan);
				armjtagew_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);

				armjtagew_tap_execute();

				if (cmd->cmd.reset->trst == 1)
					tap_set_state(TAP_RESET);
				armjtagew_reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
				break;

			case JTAG_SLEEP:
				DEBUG_JTAG_IO("sleep %i", cmd->cmd.sleep->us);
				armjtagew_tap_execute();
				jtag_sleep(cmd->cmd.sleep->us);
				break;

			default:
				LOG_ERROR("BUG: unknown JTAG command type encountered");
				exit(-1);
		}
		cmd = cmd->next;
	}

	return armjtagew_tap_execute();
}

/* Sets speed in kHz. */
static int armjtagew_speed(int speed)
{
	int result;
	int speed_real;


	usb_out_buffer[0] = CMD_SET_TCK_FREQUENCY;
	buf_set_u32(usb_out_buffer + 1, 0, 32, speed*1000);

	result = armjtagew_usb_message(armjtagew_handle, 5, 4);

	if (result < 0) {
		LOG_ERROR("ARM-JTAG-EW setting speed failed (%d)", result);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	usb_out_buffer[0] = CMD_GET_TCK_FREQUENCY;
	result = armjtagew_usb_message(armjtagew_handle, 1, 4);
	speed_real = (int)buf_get_u32(usb_in_buffer, 0, 32) / 1000;
	if (result < 0) {
		LOG_ERROR("ARM-JTAG-EW getting speed failed (%d)", result);
		return ERROR_JTAG_DEVICE_ERROR;
	} else
		LOG_INFO("Requested speed %dkHz, emulator reported %dkHz.", speed, speed_real);

	return ERROR_OK;
}

static int armjtagew_khz(int khz, int *jtag_speed)
{
	*jtag_speed = khz;

	return ERROR_OK;
}

static int armjtagew_speed_div(int speed, int *khz)
{
	*khz = speed;

	return ERROR_OK;
}

static int armjtagew_init(void)
{
	int check_cnt;

	armjtagew_handle = armjtagew_usb_open();

	if (armjtagew_handle == 0) {
		LOG_ERROR(
			"Cannot find ARM-JTAG-EW Interface! Please check connection and permissions.");
		return ERROR_JTAG_INIT_FAILED;
	}

	check_cnt = 0;
	while (check_cnt < 3) {
		if (armjtagew_get_version_info() == ERROR_OK) {
			/* attempt to get status */
			armjtagew_get_status();
			break;
		}

		check_cnt++;
	}

	if (check_cnt == 3)
		LOG_INFO("ARM-JTAG-EW initial read failed, don't worry");

	/* Initial JTAG speed (for reset and initialization): 32 kHz */
	armjtagew_speed(32);

	LOG_INFO("ARM-JTAG-EW JTAG Interface ready");

	armjtagew_reset(0, 0);
	armjtagew_tap_init();

	return ERROR_OK;
}

static int armjtagew_quit(void)
{
	armjtagew_usb_close(armjtagew_handle);
	return ERROR_OK;
}

/**************************************************************************
 * Queue command implementations */

static void armjtagew_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);
	}
}

/* Goes to the end state. */
static void armjtagew_state_move(void)
{
	int i;
	int 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;
		armjtagew_tap_append_step(tms, 0);
	}

	tap_set_state(tap_get_end_state());
}

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

	for (i = 0; i < num_states; i++) {
		/*
		 * TODO: The ARM-JTAG-EW hardware delays TDI with 3 TCK cycles when in RTCK mode.
		 * Either handle that here, or update the documentation with examples
		 * how to fix that in the configuration files.
		 */
		if (path[i] == tap_state_transition(tap_get_state(), false))
			armjtagew_tap_append_step(0, 0);
		else if (path[i] == tap_state_transition(tap_get_state(), true))
			armjtagew_tap_append_step(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 armjtagew_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) {
		armjtagew_end_state(TAP_IDLE);
		armjtagew_state_move();
	}

	/* execute num_cycles */
	for (i = 0; i < num_cycles; i++)
		armjtagew_tap_append_step(0, 0);

	/* finish in end_state */
	armjtagew_end_state(saved_end_state);
	if (tap_get_state() != tap_get_end_state())
		armjtagew_state_move();
}

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

	armjtagew_tap_ensure_space(1, scan_size + 8);

	saved_end_state = tap_get_end_state();

	/* Move to appropriate scan state */
	armjtagew_end_state(ir_scan ? TAP_IRSHIFT : TAP_DRSHIFT);

	/* Only move if we're not already there */
	if (tap_get_state() != tap_get_end_state())
		armjtagew_state_move();

	armjtagew_end_state(saved_end_state);

	/* Scan */
	armjtagew_tap_append_scan(scan_size, buffer, command);

	/* We are in Exit1, go to Pause */
	armjtagew_tap_append_step(0, 0);

	tap_set_state(ir_scan ? TAP_IRPAUSE : TAP_DRPAUSE);

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

static void armjtagew_reset(int trst, int srst)
{
	const uint8_t trst_mask = (1u << 5);
	const uint8_t srst_mask = (1u << 6);
	uint8_t val = 0;
	uint8_t outp_en = 0;
	uint8_t change_mask = 0;
	int result;

	LOG_DEBUG("trst: %i, srst: %i", trst, srst);

	if (srst == 0) {
		val |= srst_mask;
		outp_en &= ~srst_mask;		/* tristate */
		change_mask |= srst_mask;
	} else if (srst == 1) {
		val &= ~srst_mask;
		outp_en |= srst_mask;
		change_mask |= srst_mask;
	}

	if (trst == 0) {
		val |= trst_mask;
		outp_en &= ~trst_mask;		/* tristate */
		change_mask |= trst_mask;
	} else if (trst == 1) {
		val &= ~trst_mask;
		outp_en |= trst_mask;
		change_mask |= trst_mask;
	}

	usb_out_buffer[0] = CMD_SET_TAPHW_STATE;
	usb_out_buffer[1] = val;
	usb_out_buffer[2] = outp_en;
	usb_out_buffer[3] = change_mask;
	result = armjtagew_usb_write(armjtagew_handle, 4);
	if (result != 4)
		LOG_ERROR("ARM-JTAG-EW TRST/SRST pin set failed failed (%d)", result);
}

static int armjtagew_get_status(void)
{
	int result;

	usb_out_buffer[0] = CMD_GET_TAPHW_STATE;
	result = armjtagew_usb_message(armjtagew_handle, 1, 12);

	if (result == 0) {
		unsigned int u_tg = buf_get_u32(usb_in_buffer, 0, 16);
		LOG_INFO(
			"U_tg = %d mV, U_aux = %d mV, U_tgpwr = %d mV, I_tgpwr = %d mA, D1 = %d, Target power %s %s",
			(int)(buf_get_u32(usb_in_buffer + 0, 0, 16)),
			(int)(buf_get_u32(usb_in_buffer + 2, 0, 16)),
			(int)(buf_get_u32(usb_in_buffer + 4, 0, 16)),
			(int)(buf_get_u32(usb_in_buffer + 6, 0, 16)),
			usb_in_buffer[9],
			usb_in_buffer[11] ? "OVERCURRENT" : "OK",
			usb_in_buffer[10] ? "enabled" : "disabled");

		if (u_tg < 1500)
			LOG_ERROR("Vref too low. Check Target Power");
	} else
		LOG_ERROR("ARM-JTAG-EW command CMD_GET_TAPHW_STATE failed (%d)", result);

	return ERROR_OK;
}

static int armjtagew_get_version_info(void)
{
	int result;
	char sn[16];
	char auxinfo[257];

	/* query hardware version */
	usb_out_buffer[0] = CMD_GET_VERSION;
	result = armjtagew_usb_message(armjtagew_handle, 1, 4 + 15 + 256);

	if (result != 0) {
		LOG_ERROR("ARM-JTAG-EW command CMD_GET_VERSION failed (%d)", result);
		return ERROR_JTAG_DEVICE_ERROR;
	}

	memcpy(sn, usb_in_buffer + 4, 15);
	sn[15] = '\0';
	memcpy(auxinfo, usb_in_buffer + 4+15, 256);
	auxinfo[256] = '\0';

	LOG_INFO(
		"ARM-JTAG-EW firmware version %d.%d, hardware revision %c, SN=%s, Additional info: %s",	\
		usb_in_buffer[1],
		usb_in_buffer[0], \
		isgraph(usb_in_buffer[2]) ? usb_in_buffer[2] : 'X', \
		sn,
		auxinfo);

	if (1 != usb_in_buffer[1] || 6 != usb_in_buffer[0])
		LOG_WARNING(
			"ARM-JTAG-EW firmware version %d.%d is untested with this version of OpenOCD. You might experience unexpected behavior.",
			usb_in_buffer[1],
			usb_in_buffer[0]);
	return ERROR_OK;
}

COMMAND_HANDLER(armjtagew_handle_armjtagew_info_command)
{
	if (armjtagew_get_version_info() == ERROR_OK) {
		/* attempt to get status */
		armjtagew_get_status();
	}

	return ERROR_OK;
}

static const struct command_registration armjtagew_command_handlers[] = {
	{
		.name = "armjtagew_info",
		.handler = &armjtagew_handle_armjtagew_info_command,
		.mode = COMMAND_EXEC,
		.help = "query armjtagew info",
	},
	COMMAND_REGISTRATION_DONE
};

struct jtag_interface armjtagew_interface = {
	.name = "arm-jtag-ew",
	.commands = armjtagew_command_handlers,
	.transports = jtag_only,
	.execute_queue = armjtagew_execute_queue,
	.speed = armjtagew_speed,
	.speed_div = armjtagew_speed_div,
	.khz = armjtagew_khz,
	.init = armjtagew_init,
	.quit = armjtagew_quit,
};

/**************************************************************************
 * ARM-JTAG-EW tap functions */

/* 2048 is the max value we can use here */
#define ARMJTAGEW_TAP_BUFFER_SIZE 2048

static int tap_length;
static uint8_t tms_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];
static uint8_t tdi_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];
static uint8_t tdo_buffer[ARMJTAGEW_TAP_BUFFER_SIZE];

struct pending_scan_result {
	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;
};

#define MAX_PENDING_SCAN_RESULTS 256

static int pending_scan_results_length;
static struct pending_scan_result pending_scan_results_buffer[MAX_PENDING_SCAN_RESULTS];

static int last_tms;

static void armjtagew_tap_init(void)
{
	tap_length = 0;
	pending_scan_results_length = 0;
}

static void armjtagew_tap_ensure_space(int scans, int bits)
{
	int available_scans = MAX_PENDING_SCAN_RESULTS - pending_scan_results_length;
	int available_bits = ARMJTAGEW_TAP_BUFFER_SIZE * 8 - tap_length;

	if (scans > available_scans || bits > available_bits)
		armjtagew_tap_execute();
}

static void armjtagew_tap_append_step(int tms, int tdi)
{
	last_tms = tms;
	int index_local = tap_length / 8;

	if (index_local < ARMJTAGEW_TAP_BUFFER_SIZE) {
		int bit_index = tap_length % 8;
		uint8_t bit = 1 << bit_index;

		if (tms)
			tms_buffer[index_local] |= bit;
		else
			tms_buffer[index_local] &= ~bit;

		if (tdi)
			tdi_buffer[index_local] |= bit;
		else
			tdi_buffer[index_local] &= ~bit;

		tap_length++;
	} else
		LOG_ERROR("armjtagew_tap_append_step, overflow");
}

void armjtagew_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command)
{
	struct pending_scan_result *pending_scan_result =
		&pending_scan_results_buffer[pending_scan_results_length];
	int i;

	pending_scan_result->first = tap_length;
	pending_scan_result->length = length;
	pending_scan_result->command = command;
	pending_scan_result->buffer = buffer;

	for (i = 0; i < length; i++)
		armjtagew_tap_append_step((i < length-1 ? 0 : 1), (buffer[i/8] >> (i%8)) & 1);
	pending_scan_results_length++;
}

/* Pad and send a tap sequence to the device, and receive the answer.
 * For the purpose of padding we assume that we are in idle or pause state. */
static int armjtagew_tap_execute(void)
{
	int byte_length;
	int tms_offset;
	int tdi_offset;
	int i;
	int result;

	if (tap_length > 0) {
		/* Pad last byte so that tap_length is divisible by 8 */
		while (tap_length % 8 != 0) {
			/* More of the last TMS value keeps us in the same state,
			 * analogous to free-running JTAG interfaces. */
			armjtagew_tap_append_step(last_tms, 0);
		}

		byte_length = tap_length / 8;

		usb_out_buffer[0] = CMD_TAP_SHIFT;
		buf_set_u32(usb_out_buffer + 1, 0, 16, byte_length);

		tms_offset = 3;
		for (i = 0; i < byte_length; i++)
			usb_out_buffer[tms_offset + i] = flip_u32(tms_buffer[i], 8);

		tdi_offset = tms_offset + byte_length;
		for (i = 0; i < byte_length; i++)
			usb_out_buffer[tdi_offset + i] = flip_u32(tdi_buffer[i], 8);

		result = armjtagew_usb_message(armjtagew_handle,
				3 + 2 * byte_length,
				byte_length + 4);

		if (result == 0) {
			int stat_local;

			stat_local = (int)buf_get_u32(usb_in_buffer + byte_length, 0, 32);
			if (stat_local) {
				LOG_ERROR(
					"armjtagew_tap_execute, emulator returned error code %d for a CMD_TAP_SHIFT command",
					stat_local);
				return ERROR_JTAG_QUEUE_FAILED;
			}

			for (i = 0; i < byte_length; i++)
				tdo_buffer[i] = flip_u32(usb_in_buffer[i], 8);

			for (i = 0; i < pending_scan_results_length; i++) {
				struct pending_scan_result *pending_scan_result =
					&pending_scan_results_buffer[i];
				uint8_t *buffer = pending_scan_result->buffer;
				int length = pending_scan_result->length;
				int first = pending_scan_result->first;
				struct scan_command *command = pending_scan_result->command;

				/* Copy to buffer */
				buf_set_buf(tdo_buffer, first, buffer, 0, length);

				DEBUG_JTAG_IO("pending scan result, length = %d", length);

#ifdef _DEBUG_USB_COMMS_
				armjtagew_debug_buffer(buffer, byte_length);
#endif

				if (jtag_read_buffer(buffer, command) != ERROR_OK) {
					armjtagew_tap_init();
					return ERROR_JTAG_QUEUE_FAILED;
				}

				if (pending_scan_result->buffer != NULL)
					free(pending_scan_result->buffer);
			}
		} else {
			LOG_ERROR("armjtagew_tap_execute, wrong result %d, expected %d",
				result,
				byte_length);
			return ERROR_JTAG_QUEUE_FAILED;
		}

		armjtagew_tap_init();
	}

	return ERROR_OK;
}

/****************************************************************************
 * JLink USB low-level functions */

static struct armjtagew *armjtagew_usb_open()
{
	usb_init();

	const uint16_t vids[] = { USB_VID, 0 };
	const uint16_t pids[] = { USB_PID, 0 };
	struct usb_dev_handle *dev;
	if (jtag_usb_open(vids, pids, &dev) != ERROR_OK)
		return NULL;

	struct armjtagew *result = malloc(sizeof(struct armjtagew));
	result->usb_handle = dev;

#if 0
	/* usb_set_configuration required under win32 */
	usb_set_configuration(dev, dev->config[0].bConfigurationValue);
#endif
	usb_claim_interface(dev, 0);
#if 0
	/*
	 * This makes problems under Mac OS X. And is not needed
	 * under Windows. Hopefully this will not break a linux build
	 */
	usb_set_altinterface(dev, 0);
#endif
	return result;
}

static void armjtagew_usb_close(struct armjtagew *armjtagew)
{
	usb_close(armjtagew->usb_handle);
	free(armjtagew);
}

/* Send a message and receive the reply. */
static int armjtagew_usb_message(struct armjtagew *armjtagew, int out_length, int in_length)
{
	int result;

	result = armjtagew_usb_write(armjtagew, out_length);
	if (result == out_length) {
		result = armjtagew_usb_read(armjtagew, in_length);
		if (result != in_length) {
			LOG_ERROR("usb_bulk_read failed (requested=%d, result=%d)",
				in_length,
				result);
			return -1;
		}
	} else {
		LOG_ERROR("usb_bulk_write failed (requested=%d, result=%d)", out_length, result);
		return -1;
	}
	return 0;
}

/* Write data from out_buffer to USB. */
static int armjtagew_usb_write(struct armjtagew *armjtagew, int out_length)
{
	int result;

	if (out_length > ARMJTAGEW_OUT_BUFFER_SIZE) {
		LOG_ERROR("armjtagew_write illegal out_length=%d (max=%d)",
			out_length,
			ARMJTAGEW_OUT_BUFFER_SIZE);
		return -1;
	}

	result = usb_bulk_write(armjtagew->usb_handle, ARMJTAGEW_EPT_BULK_OUT, \
			(char *)usb_out_buffer, out_length, ARMJTAGEW_USB_TIMEOUT);

	DEBUG_JTAG_IO("armjtagew_usb_write, out_length = %d, result = %d", out_length, result);

#ifdef _DEBUG_USB_COMMS_
	armjtagew_debug_buffer(usb_out_buffer, out_length);
#endif
	return result;
}

/* Read data from USB into in_buffer. */
static int armjtagew_usb_read(struct armjtagew *armjtagew, int exp_in_length)
{
	int result = usb_bulk_read(armjtagew->usb_handle, ARMJTAGEW_EPT_BULK_IN, \
			(char *)usb_in_buffer, exp_in_length, ARMJTAGEW_USB_TIMEOUT);

	DEBUG_JTAG_IO("armjtagew_usb_read, result = %d", result);

#ifdef _DEBUG_USB_COMMS_
	armjtagew_debug_buffer(usb_in_buffer, result);
#endif
	return result;
}

#ifdef _DEBUG_USB_COMMS_
#define BYTES_PER_LINE  16

static void armjtagew_debug_buffer(uint8_t *buffer, int length)
{
	char line[81];
	char s[4];
	int i;
	int j;

	for (i = 0; i < length; i += BYTES_PER_LINE) {
		snprintf(line, 5, "%04x", i);
		for (j = i; j < i + BYTES_PER_LINE && j < length; j++) {
			snprintf(s, 4, " %02x", buffer[j]);
			strcat(line, s);
		}
		LOG_DEBUG("%s", line);

		/* Prevent GDB timeout (writing to log might take some time) */
		keep_alive();
	}
}
#endif