openocd/src/jtag/drivers/vsllink.c

/* SPDX-License-Identifier: GPL-2.0-or-later */

/***************************************************************************
 *   Copyright (C) 2009-2010 by Simon Qian <SimonQian@SimonQian.com>       *
 ***************************************************************************/

/* Versaloon is a programming tool for multiple MCUs.
 * It's distributed under GPLv3.
 * You can find it at http://www.Versaloon.com/.
 */

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

#include <jtag/adapter.h>
#include <jtag/interface.h>
#include <jtag/commands.h>
#include <jtag/swd.h>
#include <libusb.h>

#include "versaloon/versaloon_include.h"
#include "versaloon/versaloon.h"

static int vsllink_tms_offset;

struct pending_scan_result {
	int src_offset;
	int dest_offset;
	int length;	/* Number of bits to read */
	struct scan_command *command;	/* Corresponding scan command */
	uint8_t *ack;
	uint8_t *buffer;
	bool last;	/* indicate the last scan pending */
};

#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];

/* Queue command functions */
static void vsllink_end_state(tap_state_t state);
static void vsllink_state_move(void);
static void vsllink_path_move(int num_states, tap_state_t *path);
static void vsllink_tms(int num_bits, const uint8_t *bits);
static void vsllink_runtest(int num_cycles);
static void vsllink_stableclocks(int num_cycles, int tms);
static void vsllink_scan(bool ir_scan, enum scan_type type,
		uint8_t *buffer, int scan_size, struct scan_command *command);
static int vsllink_reset(int trst, int srst);

/* VSLLink tap buffer functions */
static void vsllink_tap_append_step(int tms, int tdi);
static void vsllink_tap_init(void);
static int  vsllink_tap_execute(void);
static void vsllink_tap_ensure_pending(int scans);
static void vsllink_tap_append_scan(int length, uint8_t *buffer,
		struct scan_command *command);

/* VSLLink SWD functions */
static int_least32_t vsllink_swd_frequency(int_least32_t hz);
static int vsllink_swd_switch_seq(enum swd_special_seq seq);

/* VSLLink lowlevel functions */
struct vsllink {
	struct libusb_context *libusb_ctx;
	struct libusb_device_handle *usb_device_handle;
};

static int vsllink_usb_open(struct vsllink *vsllink);
static void vsllink_usb_close(struct vsllink *vsllink);

static void vsllink_debug_buffer(uint8_t *buffer, int length);

static int tap_length;
static int tap_buffer_size;
static uint8_t *tms_buffer;
static uint8_t *tdi_buffer;
static uint8_t *tdo_buffer;

static bool swd_mode;

static struct vsllink *vsllink_handle;

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

	LOG_DEBUG_IO("-------------------------------------"
		" vsllink "
		"-------------------------------------");

	while (cmd) {
		switch (cmd->type) {
			case JTAG_RUNTEST:
				LOG_DEBUG_IO("runtest %i cycles, end in %s",
						cmd->cmd.runtest->num_cycles,
						tap_state_name(cmd->cmd.runtest->end_state));

				vsllink_end_state(cmd->cmd.runtest->end_state);
				vsllink_runtest(cmd->cmd.runtest->num_cycles);
				break;

			case JTAG_TLR_RESET:
				LOG_DEBUG_IO("statemove end in %s",
						tap_state_name(cmd->cmd.statemove->end_state));

				vsllink_end_state(cmd->cmd.statemove->end_state);
				vsllink_state_move();
				break;

			case JTAG_PATHMOVE:
				LOG_DEBUG_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]));

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

			case JTAG_SCAN:
				LOG_DEBUG_IO("JTAG Scan...");

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

				scan_size = jtag_build_buffer(
						cmd->cmd.scan, &buffer);

				if (cmd->cmd.scan->ir_scan)
					LOG_DEBUG_IO(
							"JTAG Scan write IR(%d bits), "
							"end in %s:",
							scan_size,
							tap_state_name(cmd->cmd.scan->end_state));

				else
					LOG_DEBUG_IO(
							"JTAG Scan write DR(%d bits), "
							"end in %s:",
							scan_size,
							tap_state_name(cmd->cmd.scan->end_state));

				if (LOG_LEVEL_IS(LOG_LVL_DEBUG_IO))
					vsllink_debug_buffer(buffer, DIV_ROUND_UP(scan_size, 8));

				type = jtag_scan_type(cmd->cmd.scan);

				vsllink_scan(cmd->cmd.scan->ir_scan,
						type, buffer, scan_size,
						cmd->cmd.scan);
				break;

			case JTAG_SLEEP:
				LOG_DEBUG_IO("sleep %" PRIu32, cmd->cmd.sleep->us);
				vsllink_tap_execute();
				jtag_sleep(cmd->cmd.sleep->us);
				break;

			case JTAG_STABLECLOCKS:
				LOG_DEBUG_IO("add %d clocks",
						cmd->cmd.stableclocks->num_cycles);

				switch (tap_get_state()) {
				case TAP_RESET:
					/* tms must be '1' to stay
					 * n TAP_RESET mode
					 */
					scan_size = 1;
					break;
				case TAP_DRSHIFT:
				case TAP_IDLE:
				case TAP_DRPAUSE:
				case TAP_IRSHIFT:
				case TAP_IRPAUSE:
					/* else, tms should be '0' */
					scan_size = 0;
					break;
				/* above stable states are OK */
				default:
					LOG_ERROR("jtag_add_clocks() "
							"in non-stable state \"%s\"",
							tap_state_name(tap_get_state())
					);
					exit(-1);
				}
				vsllink_stableclocks(cmd->cmd.stableclocks->num_cycles, scan_size);
				break;

				case JTAG_TMS:
					LOG_DEBUG_IO("add %d jtag tms",
							cmd->cmd.tms->num_bits);

					vsllink_tms(cmd->cmd.tms->num_bits, cmd->cmd.tms->bits);
					break;

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

	return vsllink_tap_execute();
}

static int vsllink_speed(int speed)
{
	if (swd_mode) {
		vsllink_swd_frequency(speed * 1000);
		return ERROR_OK;
	}

	versaloon_interface.adaptors.jtag_raw.config(0, (uint16_t)speed);
	return versaloon_interface.adaptors.peripheral_commit();
}

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

	return ERROR_OK;
}

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

	return ERROR_OK;
}

static void vsllink_free_buffer(void)
{
	free(tdi_buffer);
	tdi_buffer = NULL;

	free(tdo_buffer);
	tdo_buffer = NULL;

	free(tms_buffer);
	tms_buffer = NULL;
}

static int vsllink_quit(void)
{
	versaloon_interface.adaptors.gpio.config(0, GPIO_SRST | GPIO_TRST,
		0, 0, GPIO_SRST | GPIO_TRST);
	versaloon_interface.adaptors.gpio.fini(0);

	if (swd_mode)
		versaloon_interface.adaptors.swd.fini(0);
	else
		versaloon_interface.adaptors.jtag_raw.fini(0);

	versaloon_interface.adaptors.peripheral_commit();
	versaloon_interface.fini();

	vsllink_free_buffer();
	vsllink_usb_close(vsllink_handle);

	libusb_exit(vsllink_handle->libusb_ctx);
	free(vsllink_handle);

	return ERROR_OK;
}

static int vsllink_interface_init(void)
{
	vsllink_handle = malloc(sizeof(struct vsllink));
	if (!vsllink_handle) {
		LOG_ERROR("unable to allocate memory");
		return ERROR_FAIL;
	}

	libusb_init(&vsllink_handle->libusb_ctx);

	if (vsllink_usb_open(vsllink_handle) != ERROR_OK) {
		LOG_ERROR("Can't find USB JTAG Interface!"
			"Please check connection and permissions.");
		return ERROR_JTAG_INIT_FAILED;
	}
	LOG_DEBUG("vsllink found on %04X:%04X",
		versaloon_interface.usb_setting.vid,
		versaloon_interface.usb_setting.pid);
	versaloon_usb_device_handle = vsllink_handle->usb_device_handle;

	if (versaloon_interface.init() != ERROR_OK)
		return ERROR_FAIL;
	if (versaloon_interface.usb_setting.buf_size < 32) {
		versaloon_interface.fini();
		return ERROR_FAIL;
	}

	return ERROR_OK;
}

static int vsllink_init(void)
{
	int retval = vsllink_interface_init();
	if (retval != ERROR_OK)
		return retval;

	versaloon_interface.adaptors.gpio.init(0);
	versaloon_interface.adaptors.gpio.config(0, GPIO_SRST, 0, GPIO_SRST,
		GPIO_SRST);
	versaloon_interface.adaptors.delay.delayms(100);
	versaloon_interface.adaptors.peripheral_commit();

	if (swd_mode) {
		versaloon_interface.adaptors.gpio.config(0, GPIO_TRST, 0,
			GPIO_TRST, GPIO_TRST);
		versaloon_interface.adaptors.swd.init(0);
		vsllink_swd_frequency(adapter_get_speed_khz() * 1000);
		vsllink_swd_switch_seq(JTAG_TO_SWD);

	} else {
		/* malloc buffer size for tap */
		tap_buffer_size = versaloon_interface.usb_setting.buf_size / 2 - 32;
		vsllink_free_buffer();
		tdi_buffer = malloc(tap_buffer_size);
		tdo_buffer = malloc(tap_buffer_size);
		tms_buffer = malloc(tap_buffer_size);
		if ((!tdi_buffer) || (!tdo_buffer) || (!tms_buffer)) {
			vsllink_quit();
			return ERROR_FAIL;
		}

		versaloon_interface.adaptors.jtag_raw.init(0);
		versaloon_interface.adaptors.jtag_raw.config(0, adapter_get_speed_khz());
		versaloon_interface.adaptors.gpio.config(0, GPIO_SRST | GPIO_TRST,
			GPIO_TRST, GPIO_SRST, GPIO_SRST);
	}

	if (versaloon_interface.adaptors.peripheral_commit() != ERROR_OK)
		return ERROR_FAIL;

	vsllink_reset(0, 0);
	vsllink_tap_init();
	return ERROR_OK;
}

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

static void vsllink_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 vsllink_state_move(void)
{
	int i;
	uint8_t tms_scan = tap_get_tms_path(tap_get_state(),
			tap_get_end_state());
	uint8_t tms_scan_bits = tap_get_tms_path_len(tap_get_state(),
			tap_get_end_state());

	for (i = 0; i < tms_scan_bits; i++)
		vsllink_tap_append_step((tms_scan >> i) & 1, 0);

	tap_set_state(tap_get_end_state());
}

static void vsllink_path_move(int num_states, tap_state_t *path)
{
	for (int i = 0; i < num_states; i++) {
		if (path[i] == tap_state_transition(tap_get_state(), false))
			vsllink_tap_append_step(0, 0);
		else if (path[i] == tap_state_transition(tap_get_state(), true))
			vsllink_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 vsllink_tms(int num_bits, const uint8_t *bits)
{
	for (int i = 0; i < num_bits; i++)
		vsllink_tap_append_step((bits[i / 8] >> (i % 8)) & 1, 0);
}

static void vsllink_stableclocks(int num_cycles, int tms)
{
	while (num_cycles > 0) {
		vsllink_tap_append_step(tms, 0);
		num_cycles--;
	}
}

static void vsllink_runtest(int num_cycles)
{
	tap_state_t saved_end_state = tap_get_end_state();

	if (tap_get_state() != TAP_IDLE) {
		/* enter IDLE state */
		vsllink_end_state(TAP_IDLE);
		vsllink_state_move();
	}

	vsllink_stableclocks(num_cycles, 0);

	/* post-process */
	/* set end_state */
	vsllink_end_state(saved_end_state);
	if (tap_get_end_state() != tap_get_end_state())
		vsllink_state_move();
}

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

	saved_end_state = tap_get_end_state();

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

	if (tap_get_state() != tap_get_end_state())
		vsllink_state_move();
	vsllink_end_state(saved_end_state);

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

	/* Goto Pause and record position to insert tms:0 */
	vsllink_tap_append_step(0, 0);
	vsllink_tms_offset = tap_length;

	tap_set_state(ir_scan ? TAP_IRPAUSE : TAP_DRPAUSE);

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

static int vsllink_reset(int trst, int srst)
{
	LOG_DEBUG("trst: %i, srst: %i", trst, srst);

	if (!srst)
		versaloon_interface.adaptors.gpio.config(0, GPIO_SRST, 0, GPIO_SRST, GPIO_SRST);
	else
		versaloon_interface.adaptors.gpio.config(0, GPIO_SRST, GPIO_SRST, 0, 0);

	if (!swd_mode) {
		if (!trst)
			versaloon_interface.adaptors.gpio.out(0, GPIO_TRST, GPIO_TRST);
		else
			versaloon_interface.adaptors.gpio.out(0, GPIO_TRST, 0);
	}

	return versaloon_interface.adaptors.peripheral_commit();
}

COMMAND_HANDLER(vsllink_handle_usb_vid_command)
{
	if (CMD_ARGC != 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	COMMAND_PARSE_NUMBER(u16, CMD_ARGV[0],
		versaloon_interface.usb_setting.vid);
	return ERROR_OK;
}

COMMAND_HANDLER(vsllink_handle_usb_pid_command)
{
	if (CMD_ARGC != 1)
		return ERROR_COMMAND_SYNTAX_ERROR;
	COMMAND_PARSE_NUMBER(u16, CMD_ARGV[0],
		versaloon_interface.usb_setting.pid);
	return ERROR_OK;
}

COMMAND_HANDLER(vsllink_handle_usb_bulkin_command)
{
	if (CMD_ARGC != 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	COMMAND_PARSE_NUMBER(u8, CMD_ARGV[0],
		versaloon_interface.usb_setting.ep_in);

	versaloon_interface.usb_setting.ep_in |= 0x80;

	return ERROR_OK;
}

COMMAND_HANDLER(vsllink_handle_usb_bulkout_command)
{
	if (CMD_ARGC != 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	COMMAND_PARSE_NUMBER(u8, CMD_ARGV[0],
		versaloon_interface.usb_setting.ep_out);

	versaloon_interface.usb_setting.ep_out &= ~0x80;

	return ERROR_OK;
}

COMMAND_HANDLER(vsllink_handle_usb_interface_command)
{
	if (CMD_ARGC != 1)
		return ERROR_COMMAND_SYNTAX_ERROR;

	COMMAND_PARSE_NUMBER(u8, CMD_ARGV[0],
		versaloon_interface.usb_setting.interface);
	return ERROR_OK;
}

/**************************************************************************
 * VSLLink tap functions */

static void vsllink_tap_init(void)
{
	tap_length = 0;
	pending_scan_results_length = 0;
	vsllink_tms_offset = 0;
}

static void vsllink_tap_ensure_pending(int scans)
{
	int available_scans =
		MAX_PENDING_SCAN_RESULTS - pending_scan_results_length;

	if (scans > available_scans)
		vsllink_tap_execute();
}

static void vsllink_tap_append_step(int tms, int tdi)
{
	int index_var = tap_length / 8;

	int bit_index = tap_length % 8;
	uint8_t bit = 1 << bit_index;

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

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

	tap_length++;

	if (tap_buffer_size * 8 <= tap_length)
		vsllink_tap_execute();
}

static void vsllink_tap_append_scan(int length, uint8_t *buffer,
	struct scan_command *command)
{
	struct pending_scan_result *pending_scan_result;
	int len_tmp, len_all, i;

	len_all = 0;
	while (len_all < length) {
		vsllink_tap_ensure_pending(1);
		pending_scan_result =
			&pending_scan_results_buffer[
				pending_scan_results_length];

		if ((length - len_all) > (tap_buffer_size * 8 - tap_length)) {
			/* Use all memory available
			   vsllink_tap_append_step will commit automatically */
			len_tmp = tap_buffer_size * 8 - tap_length;
			pending_scan_result->last = false;
		} else {
			len_tmp = length - len_all;
			pending_scan_result->last = true;
		}
		pending_scan_result->src_offset = tap_length;
		pending_scan_result->dest_offset = len_all;
		pending_scan_result->length = len_tmp;
		pending_scan_result->command = command;
		pending_scan_result->buffer = buffer;
		pending_scan_results_length++;

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

		len_all += len_tmp;
	}
}

static int vsllink_jtag_execute(void)
{
	int i;
	int result;

	if (tap_length <= 0)
		return ERROR_OK;

	versaloon_interface.adaptors.jtag_raw.execute(0, tdi_buffer, tms_buffer,
		tdo_buffer, tap_length);

	result = versaloon_interface.adaptors.peripheral_commit();

	if (result == ERROR_OK) {
		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 src_first = pending_scan_result->src_offset;
			int dest_first = pending_scan_result->dest_offset;
			bool last = pending_scan_result->last;

			struct scan_command *command;

			command = pending_scan_result->command;
			buf_set_buf(tdo_buffer, src_first, buffer, dest_first, length);

			LOG_DEBUG_IO(
				"JTAG scan read(%d bits, from src %d bits to dest %d bits):",
				length, src_first, dest_first);
			if (LOG_LEVEL_IS(LOG_LVL_DEBUG_IO))
				vsllink_debug_buffer(buffer + dest_first / 8, DIV_ROUND_UP(length, 7));

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

				free(pending_scan_result->buffer);
			}
		}
	} else {
		LOG_ERROR("vsllink_jtag_execute failure");
		return ERROR_JTAG_QUEUE_FAILED;
	}

	vsllink_tap_init();

	return ERROR_OK;
}

static int vsllink_tap_execute(void)
{
	if (swd_mode)
		return ERROR_OK;

	return vsllink_jtag_execute();
}

static int vsllink_swd_init(void)
{
	LOG_INFO("VSLLink SWD mode enabled");
	swd_mode = true;

	return ERROR_OK;
}

static int_least32_t vsllink_swd_frequency(int_least32_t hz)
{
	const int_least32_t delay2hz[] = {
		1850000, 235000, 130000, 102000, 85000, 72000
	};

	if (hz > 0) {
		uint16_t delay = UINT16_MAX;

		for (uint16_t i = 0; i < ARRAY_SIZE(delay2hz); i++) {
			if (hz >= delay2hz[i]) {
				hz = delay2hz[i];
				delay = i;
				break;
			}
		}

		if (delay == UINT16_MAX)
			delay = (500000 / hz) - 1;

		/* Calculate retry count after a WAIT response. This will give
		 * a retry timeout at about ~250 ms. 54 is the number of bits
		 * found in a transaction. */
		uint16_t retry_count = 250 * hz / 1000 / 54;

		LOG_DEBUG("SWD delay: %d, retry count: %d", delay, retry_count);

		versaloon_interface.adaptors.swd.config(0, 2, retry_count, delay);
	}

	return hz;
}

static int vsllink_swd_switch_seq(enum swd_special_seq seq)
{
	switch (seq) {
	case LINE_RESET:
		LOG_DEBUG("SWD line reset");
		versaloon_interface.adaptors.swd.seqout(0, swd_seq_line_reset,
				swd_seq_line_reset_len);
		break;
	case JTAG_TO_SWD:
		LOG_DEBUG("JTAG-to-SWD");
		versaloon_interface.adaptors.swd.seqout(0, swd_seq_jtag_to_swd,
				swd_seq_jtag_to_swd_len);
		break;
	case SWD_TO_JTAG:
		LOG_DEBUG("SWD-to-JTAG");
		versaloon_interface.adaptors.swd.seqout(0, swd_seq_swd_to_jtag,
				swd_seq_swd_to_jtag_len);
		break;
	default:
		LOG_ERROR("Sequence %d not supported", seq);
		return ERROR_FAIL;
	}

	return ERROR_OK;
}

static void vsllink_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
{
	versaloon_interface.adaptors.swd.transact(0, cmd, value, NULL);
}

static void vsllink_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
{
	versaloon_interface.adaptors.swd.transact(0, cmd, &value, NULL);
}

static int vsllink_swd_run_queue(void)
{
	return versaloon_interface.adaptors.peripheral_commit();
}

/****************************************************************************
 * VSLLink USB low-level functions */

static int vsllink_check_usb_strings(
	struct libusb_device_handle *usb_device_handle,
	struct libusb_device_descriptor *usb_desc)
{
	char desc_string[256];
	int retval;

	if (adapter_get_required_serial()) {
		retval = libusb_get_string_descriptor_ascii(usb_device_handle,
			usb_desc->iSerialNumber, (unsigned char *)desc_string,
			sizeof(desc_string));
		if (retval < 0)
			return ERROR_FAIL;

		if (strncmp(desc_string, adapter_get_required_serial(),
				sizeof(desc_string)))
			return ERROR_FAIL;
	}

	retval = libusb_get_string_descriptor_ascii(usb_device_handle,
		usb_desc->iProduct, (unsigned char *)desc_string,
		sizeof(desc_string));
	if (retval < 0)
		return ERROR_FAIL;

	if (!strstr(desc_string, "Versaloon"))
		return ERROR_FAIL;

	return ERROR_OK;
}

static int vsllink_usb_open(struct vsllink *vsllink)
{
	ssize_t num_devices, i;
	struct libusb_device **usb_devices;
	struct libusb_device_descriptor usb_desc;
	struct libusb_device_handle *usb_device_handle;
	int retval;

	num_devices = libusb_get_device_list(vsllink->libusb_ctx, &usb_devices);

	if (num_devices <= 0)
		return ERROR_FAIL;

	for (i = 0; i < num_devices; i++) {
		struct libusb_device *device = usb_devices[i];

		retval = libusb_get_device_descriptor(device, &usb_desc);
		if (retval != 0)
			continue;

		if (usb_desc.idVendor != versaloon_interface.usb_setting.vid ||
			usb_desc.idProduct != versaloon_interface.usb_setting.pid)
			continue;

		retval = libusb_open(device, &usb_device_handle);
		if (retval != 0)
			continue;

		retval = vsllink_check_usb_strings(usb_device_handle, &usb_desc);
		if (retval == ERROR_OK)
			break;

		libusb_close(usb_device_handle);
	}

	libusb_free_device_list(usb_devices, 1);

	if (i == num_devices)
		return ERROR_FAIL;

	retval = libusb_claim_interface(usb_device_handle,
		versaloon_interface.usb_setting.interface);
	if (retval != 0) {
		LOG_ERROR("unable to claim interface");
		libusb_close(usb_device_handle);
		return ERROR_FAIL;
	}

	vsllink->usb_device_handle = usb_device_handle;
	return ERROR_OK;
}

static void vsllink_usb_close(struct vsllink *vsllink)
{
	libusb_release_interface(vsllink->usb_device_handle,
		versaloon_interface.usb_setting.interface);
	libusb_close(vsllink->usb_device_handle);
}

#define BYTES_PER_LINE  16

static void vsllink_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 & 0xffff);
		for (j = i; j < i + BYTES_PER_LINE && j < length; j++) {
			snprintf(s, 4, " %02x", buffer[j]);
			strcat(line, s);
		}
		LOG_DEBUG_IO("%s", line);
	}
}

static const struct command_registration vsllink_subcommand_handlers[] = {
	{
		.name = "usb_vid",
		.handler = &vsllink_handle_usb_vid_command,
		.mode = COMMAND_CONFIG,
		.help = "Set USB VID",
		.usage = "<vid>",
	},
	{
		.name = "usb_pid",
		.handler = &vsllink_handle_usb_pid_command,
		.mode = COMMAND_CONFIG,
		.help = "Set USB PID",
		.usage = "<pid>",
	},
	{
		.name = "usb_bulkin",
		.handler = &vsllink_handle_usb_bulkin_command,
		.mode = COMMAND_CONFIG,
		.help = "Set USB input endpoint",
		.usage = "<ep_in>",
	},
	{
		.name = "usb_bulkout",
		.handler = &vsllink_handle_usb_bulkout_command,
		.mode = COMMAND_CONFIG,
		.help = "Set USB output endpoint",
		.usage = "<ep_out>",
	},
	{
		.name = "usb_interface",
		.handler = &vsllink_handle_usb_interface_command,
		.mode = COMMAND_CONFIG,
		.help = "Set USB output interface",
		.usage = "<interface>",
	},
	COMMAND_REGISTRATION_DONE
};

static const struct command_registration vsllink_command_handlers[] = {
	{
		.name = "vsllink",
		.mode = COMMAND_ANY,
		.help = "perform vsllink management",
		.chain = vsllink_subcommand_handlers,
		.usage = "",
	},
	COMMAND_REGISTRATION_DONE
};

static const char * const vsllink_transports[] = {"jtag", "swd", NULL};

static const struct swd_driver vsllink_swd_driver = {
	.init = vsllink_swd_init,
	.switch_seq = vsllink_swd_switch_seq,
	.read_reg = vsllink_swd_read_reg,
	.write_reg = vsllink_swd_write_reg,
	.run = vsllink_swd_run_queue,
};

static struct jtag_interface vsllink_interface = {
	.supported = DEBUG_CAP_TMS_SEQ,
	.execute_queue = vsllink_execute_queue,
};

struct adapter_driver vsllink_adapter_driver = {
	.name = "vsllink",
	.transports = vsllink_transports,
	.commands = vsllink_command_handlers,

	.init = vsllink_init,
	.quit = vsllink_quit,
	.reset = vsllink_reset,
	.speed = vsllink_speed,
	.khz = vsllink_khz,
	.speed_div = vsllink_speed_div,

	.jtag_ops = &vsllink_interface,
	.swd_ops = &vsllink_swd_driver,
};