vsllink.c

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// 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(unsigned int num_states, tap_state_t *path);
static void vsllink_tms(int num_bits, const uint8_t *bits);
static void vsllink_runtest(unsigned int num_cycles);
static void vsllink_stableclocks(unsigned 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(struct jtag_command *cmd_queue)
{
    struct jtag_command *cmd = cmd_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 %u 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: %u 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 %u 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(unsigned int num_states, tap_state_t *path)
{
    for (unsigned 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(unsigned int num_cycles, int tms)
{
    while (num_cycles > 0) {
        vsllink_tap_append_step(tms, 0);
        num_cycles--;
    }
}
 
static void vsllink_runtest(unsigned 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,
};