cmsis_dap_usb.c

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/***************************************************************************
 *   Copyright (C) 2016 by Maksym Hilliaka                                 *
 *   oter@frozen-team.com                                                  *
 *                                                                         *
 *   Copyright (C) 2016 by Phillip Pearson                                 *
 *   pp@myelin.co.nz                                                       *
 *                                                                         *
 *   Copyright (C) 2014 by Paul Fertser                                    *
 *   fercerpav@gmail.com                                                   *
 *                                                                         *
 *   Copyright (C) 2013 by mike brown                                      *
 *   mike@theshedworks.org.uk                                              *
 *                                                                         *
 *   Copyright (C) 2013 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   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, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

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

#include <transport/transport.h>
#include <jtag/swd.h>
#include <jtag/interface.h>
#include <jtag/commands.h>
#include <jtag/tcl.h>

#include <hidapi.h>

/*
 * See CMSIS-DAP documentation:
 * Version 0.01 - Beta.
 */

/* USB Config */

/* Known vid/pid pairs:
 * VID 0xc251: Keil Software
 * PID 0xf001: LPC-Link-II CMSIS_DAP
 * PID 0xf002: OPEN-SDA CMSIS_DAP (Freedom Board)
 * PID 0x2722: Keil ULINK2 CMSIS-DAP
 *
 * VID 0x0d28: mbed Software
 * PID 0x0204: MBED CMSIS-DAP
 */

#define MAX_USB_IDS 8
/* vid = pid = 0 marks the end of the list */
static uint16_t cmsis_dap_vid[MAX_USB_IDS + 1] = { 0 };
static uint16_t cmsis_dap_pid[MAX_USB_IDS + 1] = { 0 };
static wchar_t *cmsis_dap_serial;
static bool swd_mode;

#define PACKET_SIZE       (64 + 1)  /* 64 bytes plus report id */
#define USB_TIMEOUT       1000

/* CMSIS-DAP General Commands */
#define CMD_DAP_INFO              0x00
#define CMD_DAP_LED               0x01
#define CMD_DAP_CONNECT           0x02
#define CMD_DAP_DISCONNECT        0x03
#define CMD_DAP_WRITE_ABORT       0x08
#define CMD_DAP_DELAY             0x09
#define CMD_DAP_RESET_TARGET      0x0A

/* CMD_INFO */
#define INFO_ID_VID               0x00      /* string */
#define INFO_ID_PID               0x02      /* string */
#define INFO_ID_SERNUM            0x03      /* string */
#define INFO_ID_FW_VER            0x04      /* string */
#define INFO_ID_TD_VEND           0x05      /* string */
#define INFO_ID_TD_NAME           0x06      /* string */
#define INFO_ID_CAPS              0xf0      /* byte */
#define INFO_ID_PKT_CNT           0xfe      /* byte */
#define INFO_ID_PKT_SZ            0xff      /* short */

#define INFO_CAPS_SWD             0x01
#define INFO_CAPS_JTAG            0x02

/* CMD_LED */
#define LED_ID_CONNECT            0x00
#define LED_ID_RUN                0x01

#define LED_OFF                   0x00
#define LED_ON                    0x01

/* CMD_CONNECT */
#define CONNECT_DEFAULT           0x00
#define CONNECT_SWD               0x01
#define CONNECT_JTAG              0x02

/* CMSIS-DAP Common SWD/JTAG Commands */
#define CMD_DAP_DELAY             0x09
#define CMD_DAP_SWJ_PINS          0x10
#define CMD_DAP_SWJ_CLOCK         0x11
#define CMD_DAP_SWJ_SEQ           0x12

/*
 * PINS
 * Bit 0: SWCLK/TCK
 * Bit 1: SWDIO/TMS
 * Bit 2: TDI
 * Bit 3: TDO
 * Bit 5: nTRST
 * Bit 7: nRESET
 */

#define SWJ_PIN_TCK               (1<<0)
#define SWJ_PIN_TMS               (1<<1)
#define SWJ_PIN_TDI               (1<<2)
#define SWJ_PIN_TDO               (1<<3)
#define SWJ_PIN_TRST              (1<<5)
#define SWJ_PIN_SRST              (1<<7)

/* CMSIS-DAP SWD Commands */
#define CMD_DAP_SWD_CONFIGURE     0x13

/* CMSIS-DAP JTAG Commands */
#define CMD_DAP_JTAG_SEQ          0x14
#define CMD_DAP_JTAG_CONFIGURE    0x15
#define CMD_DAP_JTAG_IDCODE       0x16

/* CMSIS-DAP JTAG sequence info masks */
/* Number of bits to clock through (0 means 64) */
#define DAP_JTAG_SEQ_TCK          0x3F
/* TMS will be set during the sequence if this bit is set */
#define DAP_JTAG_SEQ_TMS          0x40
/* TDO output will be captured if this bit is set */
#define DAP_JTAG_SEQ_TDO          0x80


/* CMSIS-DAP Transfer Commands */
#define CMD_DAP_TFER_CONFIGURE    0x04
#define CMD_DAP_TFER              0x05
#define CMD_DAP_TFER_BLOCK        0x06
#define CMD_DAP_TFER_ABORT        0x07

/* DAP Status Code */
#define DAP_OK                    0
#define DAP_ERROR                 0xFF

/* CMSIS-DAP Vendor Commands
 * None as yet... */

static const char * const info_caps_str[] = {
    "SWD  Supported",
    "JTAG Supported"
};

/* max clock speed (kHz) */
#define DAP_MAX_CLOCK             5000

struct cmsis_dap {
    hid_device *dev_handle;
    uint16_t packet_size;
    uint16_t packet_count;
    uint8_t *packet_buffer;
    uint8_t caps;
    uint8_t mode;
};

struct pending_transfer_result {
    uint8_t cmd;
    uint32_t data;
    void *buffer;
};

struct pending_scan_result {
    unsigned first;
    unsigned length;
    uint8_t *buffer;
    unsigned buffer_offset;
};

static int pending_transfer_count, pending_queue_len;
static struct pending_transfer_result *pending_transfers;

/* pointers to buffers that will receive jtag scan results on the next flush */
#define MAX_PENDING_SCAN_RESULTS 256
static int pending_scan_result_count;
static struct pending_scan_result pending_scan_results[MAX_PENDING_SCAN_RESULTS];

/* queued JTAG sequences that will be executed on the next flush */
#define QUEUED_SEQ_BUF_LEN (cmsis_dap_handle->packet_size - 3)
static int queued_seq_count;
static int queued_seq_buf_end;
static int queued_seq_tdo_ptr;
static uint8_t queued_seq_buf[1024]; /* TODO: make dynamic / move into cmsis object */

static int queued_retval;

static struct cmsis_dap *cmsis_dap_handle;

static int cmsis_dap_usb_open(void)
{
    hid_device *dev = NULL;
    int i;
    struct hid_device_info *devs, *cur_dev;
    unsigned short target_vid, target_pid;
    wchar_t *target_serial = NULL;

    bool found = false;
    bool serial_found = false;

    target_vid = 0;
    target_pid = 0;

    /*
     * The CMSIS-DAP specification stipulates:
     * "The Product String must contain "CMSIS-DAP" somewhere in the string. This is used by the
     * debuggers to identify a CMSIS-DAP compliant Debug Unit that is connected to a host computer."
     */
    devs = hid_enumerate(0x0, 0x0);
    cur_dev = devs;
    while (NULL != cur_dev) {
        if (0 == cmsis_dap_vid[0]) {
            if (NULL == cur_dev->product_string) {
                LOG_DEBUG("Cannot read product string of device 0x%x:0x%x",
                      cur_dev->vendor_id, cur_dev->product_id);
            } else {
                if (wcsstr(cur_dev->product_string, L"CMSIS-DAP")) {
                    /* if the user hasn't specified VID:PID *and*
                     * product string contains "CMSIS-DAP", pick it
                     */
                    found = true;
                }
            }
        } else {
            /* otherwise, exhaustively compare against all VID:PID in list */
            for (i = 0; cmsis_dap_vid[i] || cmsis_dap_pid[i]; i++) {
                if ((cmsis_dap_vid[i] == cur_dev->vendor_id) && (cmsis_dap_pid[i] == cur_dev->product_id))
                    found = true;
            }

            if (cmsis_dap_vid[i] || cmsis_dap_pid[i])
                found = true;
        }

        if (found) {
            /* we have found an adapter, so exit further checks */
            /* check serial number matches if given */
            if (cmsis_dap_serial != NULL) {
                if ((cur_dev->serial_number != NULL) && wcscmp(cmsis_dap_serial, cur_dev->serial_number) == 0) {
                    serial_found = true;
                    break;
                }
            } else
                break;

            found = false;
        }

        cur_dev = cur_dev->next;
    }

    if (NULL != cur_dev) {
        target_vid = cur_dev->vendor_id;
        target_pid = cur_dev->product_id;
        if (serial_found)
            target_serial = cmsis_dap_serial;
    }

    hid_free_enumeration(devs);

    if (target_vid == 0 && target_pid == 0) {
        LOG_ERROR("unable to find CMSIS-DAP device");
        return ERROR_FAIL;
    }

    if (hid_init() != 0) {
        LOG_ERROR("unable to open HIDAPI");
        return ERROR_FAIL;
    }

    dev = hid_open(target_vid, target_pid, target_serial);

    if (dev == NULL) {
        LOG_ERROR("unable to open CMSIS-DAP device 0x%x:0x%x", target_vid, target_pid);
        return ERROR_FAIL;
    }

    struct cmsis_dap *dap = malloc(sizeof(struct cmsis_dap));
    if (dap == NULL) {
        LOG_ERROR("unable to allocate memory");
        return ERROR_FAIL;
    }

    dap->dev_handle = dev;
    dap->caps = 0;
    dap->mode = 0;

    cmsis_dap_handle = dap;

    /* allocate default packet buffer, may be changed later.
     * currently with HIDAPI we have no way of getting the output report length
     * without this info we cannot communicate with the adapter.
     * For the moment we ahve to hard code the packet size */

    int packet_size = PACKET_SIZE;

    /* atmel cmsis-dap uses 512 byte reports */
    /* except when it doesn't e.g. with mEDBG on SAMD10 Xplained
     * board */
    /* TODO: HID report descriptor should be parsed instead of
     * hardcoding a match by VID */
    if (target_vid == 0x03eb && target_pid != 0x2145)
        packet_size = 512 + 1;

    cmsis_dap_handle->packet_buffer = malloc(packet_size);
    cmsis_dap_handle->packet_size = packet_size;

    if (cmsis_dap_handle->packet_buffer == NULL) {
        LOG_ERROR("unable to allocate memory");
        return ERROR_FAIL;
    }

    return ERROR_OK;
}

static void cmsis_dap_usb_close(struct cmsis_dap *dap)
{
    hid_close(dap->dev_handle);
    hid_exit();

    free(cmsis_dap_handle->packet_buffer);
    free(cmsis_dap_handle);
    cmsis_dap_handle = NULL;
    free(cmsis_dap_serial);
    cmsis_dap_serial = NULL;
    free(pending_transfers);
    pending_transfers = NULL;

    return;
}

/* Send a message and receive the reply */
static int cmsis_dap_usb_xfer(struct cmsis_dap *dap, int txlen)
{
#ifdef CMSIS_DAP_JTAG_DEBUG
    LOG_DEBUG("cmsis-dap usb xfer cmd=%02X", dap->packet_buffer[1]);
#endif
    /* Pad the rest of the TX buffer with 0's */
    memset(dap->packet_buffer + txlen, 0, dap->packet_size - txlen);

    /* write data to device */
    int retval = hid_write(dap->dev_handle, dap->packet_buffer, dap->packet_size);
    if (retval == -1) {
        LOG_ERROR("error writing data: %ls", hid_error(dap->dev_handle));
        return ERROR_FAIL;
    }

    /* get reply */
    retval = hid_read_timeout(dap->dev_handle, dap->packet_buffer, dap->packet_size, USB_TIMEOUT);
    if (retval == -1 || retval == 0) {
        LOG_DEBUG("error reading data: %ls", hid_error(dap->dev_handle));
        return ERROR_FAIL;
    }

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWJ_Pins(uint8_t pins, uint8_t mask, uint32_t delay, uint8_t *input)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_SWJ_PINS;
    buffer[2] = pins;
    buffer[3] = mask;
    buffer[4] = delay & 0xff;
    buffer[5] = (delay >> 8) & 0xff;
    buffer[6] = (delay >> 16) & 0xff;
    buffer[7] = (delay >> 24) & 0xff;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 8);

    if (retval != ERROR_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_DAP_SWJ_PINS failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    if (input)
        *input = buffer[1];

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWJ_Clock(uint32_t swj_clock)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    /* set clock in Hz */
    swj_clock *= 1000;
    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_SWJ_CLOCK;
    buffer[2] = swj_clock & 0xff;
    buffer[3] = (swj_clock >> 8) & 0xff;
    buffer[4] = (swj_clock >> 16) & 0xff;
    buffer[5] = (swj_clock >> 24) & 0xff;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 6);

    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_DAP_SWJ_CLOCK failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

/* clock a sequence of bits out on TMS, to change JTAG states */
static int cmsis_dap_cmd_DAP_SWJ_Sequence(uint8_t s_len, const uint8_t *sequence)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

#ifdef CMSIS_DAP_JTAG_DEBUG
    LOG_DEBUG("cmsis-dap TMS sequence: len=%d", s_len);
    for (int i = 0; i < DIV_ROUND_UP(s_len, 8); ++i)
        printf("%02X ", sequence[i]);

    printf("\n");
#endif

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_SWJ_SEQ;
    buffer[2] = s_len;
    bit_copy(&buffer[3], 0, sequence, 0, s_len);

    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, DIV_ROUND_UP(s_len, 8) + 3);

    if (retval != ERROR_OK || buffer[1] != DAP_OK)
        return ERROR_FAIL;

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Info(uint8_t info, uint8_t **data)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_INFO;
    buffer[2] = info;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

    if (retval != ERROR_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_INFO failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    *data = &(buffer[1]);

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_LED(uint8_t leds)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_LED;
    buffer[2] = 0x00;
    buffer[3] = leds;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 4);

    if (retval != ERROR_OK || buffer[1] != 0x00) {
        LOG_ERROR("CMSIS-DAP command CMD_LED failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Connect(uint8_t mode)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_CONNECT;
    buffer[2] = mode;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

    if (retval != ERROR_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_CONNECT failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    if (buffer[1] != mode) {
        LOG_ERROR("CMSIS-DAP failed to connect in mode (%d)", mode);
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Disconnect(void)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_DISCONNECT;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 2);

    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_DISCONNECT failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_TFER_Configure(uint8_t idle, uint16_t retry_count, uint16_t match_retry)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_TFER_CONFIGURE;
    buffer[2] = idle;
    buffer[3] = retry_count & 0xff;
    buffer[4] = (retry_count >> 8) & 0xff;
    buffer[5] = match_retry & 0xff;
    buffer[6] = (match_retry >> 8) & 0xff;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 7);

    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_TFER_Configure failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWD_Configure(uint8_t cfg)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_SWD_CONFIGURE;
    buffer[2] = cfg;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_SWD_Configure failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}

#if 0
static int cmsis_dap_cmd_DAP_Delay(uint16_t delay_us)
{
    int retval;
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_DELAY;
    buffer[2] = delay_us & 0xff;
    buffer[3] = (delay_us >> 8) & 0xff;
    retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 4);

    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_Delay failed.");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    return ERROR_OK;
}
#endif

static int cmsis_dap_swd_run_queue(void)
{
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;

    LOG_DEBUG("Executing %d queued transactions", pending_transfer_count);

    if (queued_retval != ERROR_OK) {
        LOG_DEBUG("Skipping due to previous errors: %d", queued_retval);
        goto skip;
    }

    if (!pending_transfer_count)
        goto skip;

    size_t idx = 0;
    buffer[idx++] = 0;  /* report number */
    buffer[idx++] = CMD_DAP_TFER;
    buffer[idx++] = 0x00;   /* DAP Index */
    buffer[idx++] = pending_transfer_count;

    for (int i = 0; i < pending_transfer_count; i++) {
        uint8_t cmd = pending_transfers[i].cmd;
        uint32_t data = pending_transfers[i].data;

        LOG_DEBUG("%s %s reg %x %"PRIx32,
                cmd & SWD_CMD_APnDP ? "AP" : "DP",
                cmd & SWD_CMD_RnW ? "read" : "write",
              (cmd & SWD_CMD_A32) >> 1, data);

        /* When proper WAIT handling is implemented in the
         * common SWD framework, this kludge can be
         * removed. However, this might lead to minor
         * performance degradation as the adapter wouldn't be
         * able to automatically retry anything (because ARM
         * has forgotten to implement sticky error flags
         * clearing). See also comments regarding
         * cmsis_dap_cmd_DAP_TFER_Configure() and
         * cmsis_dap_cmd_DAP_SWD_Configure() in
         * cmsis_dap_init().
         */
        if (!(cmd & SWD_CMD_RnW) &&
            !(cmd & SWD_CMD_APnDP) &&
            (cmd & SWD_CMD_A32) >> 1 == DP_CTRL_STAT &&
            (data & CORUNDETECT)) {
            LOG_DEBUG("refusing to enable sticky overrun detection");
            data &= ~CORUNDETECT;
        }

        buffer[idx++] = (cmd >> 1) & 0x0f;
        if (!(cmd & SWD_CMD_RnW)) {
            buffer[idx++] = (data) & 0xff;
            buffer[idx++] = (data >> 8) & 0xff;
            buffer[idx++] = (data >> 16) & 0xff;
            buffer[idx++] = (data >> 24) & 0xff;
        }
    }

    queued_retval = cmsis_dap_usb_xfer(cmsis_dap_handle, idx);
    if (queued_retval != ERROR_OK)
        goto skip;

    idx = 2;
    uint8_t ack = buffer[idx] & 0x07;
    if (ack != SWD_ACK_OK || (buffer[idx] & 0x08)) {
        LOG_DEBUG("SWD ack not OK: %d %s", buffer[idx-1],
              ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK");
        queued_retval = ack == SWD_ACK_WAIT ? ERROR_WAIT : ERROR_FAIL;
        goto skip;
    }
    idx++;

    if (pending_transfer_count != buffer[1])
        LOG_ERROR("CMSIS-DAP transfer count mismatch: expected %d, got %d",
              pending_transfer_count, buffer[1]);

    for (int i = 0; i < buffer[1]; i++) {
        if (pending_transfers[i].cmd & SWD_CMD_RnW) {
            static uint32_t last_read;
            uint32_t data = le_to_h_u32(&buffer[idx]);
            uint32_t tmp = data;
            idx += 4;

            LOG_DEBUG("Read result: %"PRIx32, data);

            /* Imitate posted AP reads */
            if ((pending_transfers[i].cmd & SWD_CMD_APnDP) ||
                ((pending_transfers[i].cmd & SWD_CMD_A32) >> 1 == DP_RDBUFF)) {
                tmp = last_read;
                last_read = data;
            }

            if (pending_transfers[i].buffer)
                *(uint32_t *)pending_transfers[i].buffer = tmp;
        }
    }

skip:
    pending_transfer_count = 0;
    int retval = queued_retval;
    queued_retval = ERROR_OK;

    return retval;
}

static void cmsis_dap_swd_queue_cmd(uint8_t cmd, uint32_t *dst, uint32_t data)
{
    if (pending_transfer_count == pending_queue_len) {
        /* Not enough room in the queue. Run the queue. */
        queued_retval = cmsis_dap_swd_run_queue();
    }

    if (queued_retval != ERROR_OK)
        return;

    pending_transfers[pending_transfer_count].data = data;
    pending_transfers[pending_transfer_count].cmd = cmd;
    if (cmd & SWD_CMD_RnW) {
        /* Queue a read transaction */
        pending_transfers[pending_transfer_count].buffer = dst;
    }
    pending_transfer_count++;
}

static void cmsis_dap_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
{
    assert(!(cmd & SWD_CMD_RnW));
    cmsis_dap_swd_queue_cmd(cmd, NULL, value);
}

static void cmsis_dap_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
{
    assert(cmd & SWD_CMD_RnW);
    cmsis_dap_swd_queue_cmd(cmd, value, 0);
}

static int cmsis_dap_get_version_info(void)
{
    uint8_t *data;

    /* INFO_ID_FW_VER - string */
    int retval = cmsis_dap_cmd_DAP_Info(INFO_ID_FW_VER, &data);
    if (retval != ERROR_OK)
        return retval;

    if (data[0]) /* strlen */
        LOG_INFO("CMSIS-DAP: FW Version = %s", &data[1]);

    return ERROR_OK;
}

static int cmsis_dap_get_caps_info(void)
{
    uint8_t *data;

    /* INFO_ID_CAPS - byte */
    int retval = cmsis_dap_cmd_DAP_Info(INFO_ID_CAPS, &data);
    if (retval != ERROR_OK)
        return retval;

    if (data[0] == 1) {
        uint8_t caps = data[1];

        cmsis_dap_handle->caps = caps;

        if (caps & INFO_CAPS_SWD)
            LOG_INFO("CMSIS-DAP: %s", info_caps_str[0]);
        if (caps & INFO_CAPS_JTAG)
            LOG_INFO("CMSIS-DAP: %s", info_caps_str[1]);
    }

    return ERROR_OK;
}

static int cmsis_dap_get_status(void)
{
    uint8_t d;

    int retval = cmsis_dap_cmd_DAP_SWJ_Pins(0, 0, 0, &d);

    if (retval == ERROR_OK) {
        LOG_INFO("SWCLK/TCK = %d SWDIO/TMS = %d TDI = %d TDO = %d nTRST = %d nRESET = %d",
            (d & SWJ_PIN_TCK) ? 1 : 0,
            (d & SWJ_PIN_TMS) ? 1 : 0,
            (d & SWJ_PIN_TDI) ? 1 : 0,
            (d & SWJ_PIN_TDO) ? 1 : 0,
            (d & SWJ_PIN_TRST) ? 1 : 0,
            (d & SWJ_PIN_SRST) ? 1 : 0);
    }

    return retval;
}

static int cmsis_dap_swd_switch_seq(enum swd_special_seq seq)
{
    const uint8_t *s;
    unsigned int s_len;
    int retval;

    /* First disconnect before connecting, Atmel EDBG needs it for SAMD/R/L/C */
    cmsis_dap_cmd_DAP_Disconnect();

    /* When we are reconnecting, DAP_Connect needs to be rerun, at
     * least on Keil ULINK-ME */
    retval = cmsis_dap_cmd_DAP_Connect(seq == LINE_RESET || seq == JTAG_TO_SWD ?
                       CONNECT_SWD : CONNECT_JTAG);
    if (retval != ERROR_OK)
        return retval;

    switch (seq) {
    case LINE_RESET:
        LOG_DEBUG("SWD line reset");
        s = swd_seq_line_reset;
        s_len = swd_seq_line_reset_len;
        break;
    case JTAG_TO_SWD:
        LOG_DEBUG("JTAG-to-SWD");
        s = swd_seq_jtag_to_swd;
        s_len = swd_seq_jtag_to_swd_len;
        break;
    case SWD_TO_JTAG:
        LOG_DEBUG("SWD-to-JTAG");
        s = swd_seq_swd_to_jtag;
        s_len = swd_seq_swd_to_jtag_len;
        break;
    default:
        LOG_ERROR("Sequence %d not supported", seq);
        return ERROR_FAIL;
    }

    return cmsis_dap_cmd_DAP_SWJ_Sequence(s_len, s);
}

static int cmsis_dap_swd_open(void)
{
    int retval;

    if (cmsis_dap_handle == NULL) {
        /* SWD init */
        retval = cmsis_dap_usb_open();
        if (retval != ERROR_OK)
            return retval;

        retval = cmsis_dap_get_caps_info();
        if (retval != ERROR_OK)
            return retval;
    }

    if (!(cmsis_dap_handle->caps & INFO_CAPS_SWD)) {
        LOG_ERROR("CMSIS-DAP: SWD not supported");
        return ERROR_JTAG_DEVICE_ERROR;
    }

    retval = cmsis_dap_cmd_DAP_Connect(CONNECT_SWD);
    if (retval != ERROR_OK)
        return retval;

    /* Add more setup here.??... */

    LOG_INFO("CMSIS-DAP: Interface Initialised (SWD)");
    return ERROR_OK;
}

static int cmsis_dap_init(void)
{
    int retval;
    uint8_t *data;

    if (swd_mode) {
        retval = cmsis_dap_swd_open();
        if (retval != ERROR_OK)
            return retval;
    }

    if (cmsis_dap_handle == NULL) {

        /* JTAG init */
        retval = cmsis_dap_usb_open();
        if (retval != ERROR_OK)
            return retval;

        retval = cmsis_dap_get_caps_info();
        if (retval != ERROR_OK)
            return retval;

        /* Connect in JTAG mode */
        if (!(cmsis_dap_handle->caps & INFO_CAPS_JTAG)) {
            LOG_ERROR("CMSIS-DAP: JTAG not supported");
            return ERROR_JTAG_DEVICE_ERROR;
        }

        retval = cmsis_dap_cmd_DAP_Connect(CONNECT_JTAG);
        if (retval != ERROR_OK)
            return retval;

        LOG_INFO("CMSIS-DAP: Interface Initialised (JTAG)");
    }

    retval = cmsis_dap_get_version_info();
    if (retval != ERROR_OK)
        return retval;

    /* INFO_ID_PKT_SZ - short */
    retval = cmsis_dap_cmd_DAP_Info(INFO_ID_PKT_SZ, &data);
    if (retval != ERROR_OK)
        return retval;

    if (data[0] == 2) {  /* short */
        uint16_t pkt_sz = data[1] + (data[2] << 8);

        /* 4 bytes of command header + 5 bytes per register
         * write. For bulk read sequences just 4 bytes are
         * needed per transfer, so this is suboptimal. */
        pending_queue_len = (pkt_sz - 4) / 5;
        pending_transfers = malloc(pending_queue_len * sizeof(*pending_transfers));
        if (!pending_transfers) {
            LOG_ERROR("Unable to allocate memory for CMSIS-DAP queue");
            return ERROR_FAIL;
        }

        if (cmsis_dap_handle->packet_size != pkt_sz + 1) {
            /* reallocate buffer */
            cmsis_dap_handle->packet_size = pkt_sz + 1;
            cmsis_dap_handle->packet_buffer = realloc(cmsis_dap_handle->packet_buffer,
                    cmsis_dap_handle->packet_size);
            if (cmsis_dap_handle->packet_buffer == NULL) {
                LOG_ERROR("unable to reallocate memory");
                return ERROR_FAIL;
            }
        }

        LOG_DEBUG("CMSIS-DAP: Packet Size = %" PRId16, pkt_sz);
    }

    /* INFO_ID_PKT_CNT - byte */
    retval = cmsis_dap_cmd_DAP_Info(INFO_ID_PKT_CNT, &data);
    if (retval != ERROR_OK)
        return retval;

    if (data[0] == 1) { /* byte */
        uint16_t pkt_cnt = data[1];
        cmsis_dap_handle->packet_count = pkt_cnt;
        LOG_DEBUG("CMSIS-DAP: Packet Count = %" PRId16, pkt_cnt);
    }

    retval = cmsis_dap_get_status();
    if (retval != ERROR_OK)
        return ERROR_FAIL;

    /* Now try to connect to the target
     * TODO: This is all SWD only @ present */
    retval = cmsis_dap_cmd_DAP_SWJ_Clock(jtag_get_speed_khz());
    if (retval != ERROR_OK)
        return ERROR_FAIL;

    /* Ask CMSIS-DAP to automatically retry on receiving WAIT for
     * up to 64 times. This must be changed to 0 if sticky
     * overrun detection is enabled. */
    retval = cmsis_dap_cmd_DAP_TFER_Configure(0, 64, 0);
    if (retval != ERROR_OK)
        return ERROR_FAIL;
    /* Data Phase (bit 2) must be set to 1 if sticky overrun
     * detection is enabled */
    retval = cmsis_dap_cmd_DAP_SWD_Configure(0);    /* 1 TRN, no Data Phase */
    if (retval != ERROR_OK)
        return ERROR_FAIL;

    retval = cmsis_dap_cmd_DAP_LED(0x03);       /* Both LEDs on */
    if (retval != ERROR_OK)
        return ERROR_FAIL;

    /* support connecting with srst asserted */
    enum reset_types jtag_reset_config = jtag_get_reset_config();

    if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
        if (jtag_reset_config & RESET_SRST_NO_GATING) {
            retval = cmsis_dap_cmd_DAP_SWJ_Pins(0, (1 << 7), 0, NULL);
            if (retval != ERROR_OK)
                return ERROR_FAIL;
            LOG_INFO("Connecting under reset");
        }
    }

    cmsis_dap_cmd_DAP_LED(0x00);            /* Both LEDs off */

    LOG_INFO("CMSIS-DAP: Interface ready");

    return ERROR_OK;
}

static int cmsis_dap_swd_init(void)
{
    swd_mode = true;
    return ERROR_OK;
}

static int cmsis_dap_quit(void)
{
    cmsis_dap_cmd_DAP_Disconnect();
    cmsis_dap_cmd_DAP_LED(0x00);        /* Both LEDs off */

    cmsis_dap_usb_close(cmsis_dap_handle);

    return ERROR_OK;
}

static void cmsis_dap_execute_reset(struct jtag_command *cmd)
{
    /* Set both TRST and SRST even if they're not enabled as
     * there's no way to tristate them */
    uint8_t pins = 0;

    if (!cmd->cmd.reset->srst)
        pins |= SWJ_PIN_SRST;
    if (!cmd->cmd.reset->trst)
        pins |= SWJ_PIN_TRST;

    int retval = cmsis_dap_cmd_DAP_SWJ_Pins(pins,
            SWJ_PIN_TRST | SWJ_PIN_SRST, 0, NULL);
    if (retval != ERROR_OK)
        LOG_ERROR("CMSIS-DAP: Interface reset failed");
}

static void cmsis_dap_execute_sleep(struct jtag_command *cmd)
{
#if 0
    int retval = cmsis_dap_cmd_DAP_Delay(cmd->cmd.sleep->us);
    if (retval != ERROR_OK)
#endif
        jtag_sleep(cmd->cmd.sleep->us);
}

/* Set TMS high for five TCK clocks, to move the TAP to the Test-Logic-Reset state */
static int cmsis_dap_execute_tlr_reset(struct jtag_command *cmd)
{
    LOG_INFO("cmsis-dap JTAG TLR_RESET");
    uint8_t seq = 0xff;
    int ret = cmsis_dap_cmd_DAP_SWJ_Sequence(8, &seq);
    if (ret == ERROR_OK)
        tap_set_state(TAP_RESET);
    return ret;
}

/* Set new end state */
static void cmsis_dap_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);
    }
}

#ifdef SPRINT_BINARY
static void sprint_binary(char *s, const uint8_t *buf, int offset, int len)
{
    if (!len)
        return;

    /*
    buf = { 0x18 } len=5 should result in: 11000
    buf = { 0xff 0x18 } len=13 should result in: 11111111 11000
    buf = { 0xc0 0x18 } offset=3 len=10 should result in: 11000 11000
        i=3 there means i/8 = 0 so c = 0xFF, and
    */
    for (int i = offset; i < offset + len; ++i) {
        uint8_t c = buf[i / 8], mask = 1 << (i % 8);
        if ((i != offset) && !(i % 8))
            putchar(' ');
        *s++ = (c & mask) ? '1' : '0';
    }
    *s = 0;
}
#endif

#ifdef CMSIS_DAP_JTAG_DEBUG
static void debug_parse_cmsis_buf(const uint8_t *cmd, int cmdlen)
{
    /* cmd is a usb packet to go to the cmsis-dap interface */
    printf("cmsis-dap buffer (%d b): ", cmdlen);
    for (int i = 0; i < cmdlen; ++i)
        printf(" %02x", cmd[i]);
    printf("\n");
    switch (cmd[1]) {
        case CMD_DAP_JTAG_SEQ: {
            printf("cmsis-dap jtag sequence command %02x (n=%d)\n", cmd[1], cmd[2]);
            /*
             * #2 = number of sequences
             * #3 = sequence info 1
             * #4...4+n_bytes-1 = sequence 1
             * #4+n_bytes = sequence info 2
             * #5+n_bytes = sequence 2 (single bit)
             */
            int pos = 3;
            for (int seq = 0; seq < cmd[2]; ++seq) {
                uint8_t info = cmd[pos++];
                int len = info & DAP_JTAG_SEQ_TCK;
                if (len == 0)
                    len = 64;
                printf("  sequence %d starting %d: info %02x (len=%d tms=%d read_tdo=%d): ",
                    seq, pos, info, len, info & DAP_JTAG_SEQ_TMS, info & DAP_JTAG_SEQ_TDO);
                for (int i = 0; i < DIV_ROUND_UP(len, 8); ++i)
                    printf(" %02x", cmd[pos+i]);
                pos += DIV_ROUND_UP(len, 8);
                printf("\n");
            }
            if (pos != cmdlen) {
                printf("BUFFER LENGTH MISMATCH looks like %d but %d specified", pos, cmdlen);
                exit(-1);
            }

            break;
        }
        default:
            LOG_DEBUG("unknown cmsis-dap command %02x", cmd[1]);
            break;
    }
}
#endif

static void cmsis_dap_flush(void)
{
    if (!queued_seq_count)
        return;

    DEBUG_JTAG_IO("Flushing %d queued sequences (%d bytes) with %d pending scan results to capture",
        queued_seq_count, queued_seq_buf_end, pending_scan_result_count);

    /* prep CMSIS-DAP packet */
    uint8_t *buffer = cmsis_dap_handle->packet_buffer;
    buffer[0] = 0;  /* report number */
    buffer[1] = CMD_DAP_JTAG_SEQ;
    buffer[2] = queued_seq_count;
    memcpy(buffer + 3, queued_seq_buf, queued_seq_buf_end);

#ifdef CMSIS_DAP_JTAG_DEBUG
    debug_parse_cmsis_buf(buffer, queued_seq_buf_end + 3);
#endif

    /* send command to USB device */
    int retval = cmsis_dap_usb_xfer(cmsis_dap_handle, queued_seq_buf_end + 3);
    if (retval != ERROR_OK || buffer[1] != DAP_OK) {
        LOG_ERROR("CMSIS-DAP command CMD_DAP_JTAG_SEQ failed.");
        exit(-1);
    }

#ifdef CMSIS_DAP_JTAG_DEBUG
    DEBUG_JTAG_IO("USB response buf:");
    for (int c = 0; c < queued_seq_buf_end + 3; ++c)
        printf("%02X ", buffer[c]);
    printf("\n");
#endif

    /* copy scan results into client buffers */
    for (int i = 0; i < pending_scan_result_count; ++i) {
        struct pending_scan_result *scan = &pending_scan_results[i];
        DEBUG_JTAG_IO("Copying pending_scan_result %d/%d: %d bits from byte %d -> buffer + %d bits",
            i, pending_scan_result_count, scan->length, scan->first + 2, scan->buffer_offset);
#ifdef CMSIS_DAP_JTAG_DEBUG
        for (uint32_t b = 0; b < DIV_ROUND_UP(scan->length, 8); ++b)
            printf("%02X ", buffer[2+scan->first+b]);
        printf("\n");
#endif
        bit_copy(scan->buffer, scan->buffer_offset, buffer + 2 + scan->first, 0, scan->length);
    }

    /* reset */
    queued_seq_count = 0;
    queued_seq_buf_end = 0;
    queued_seq_tdo_ptr = 0;
    pending_scan_result_count = 0;
}

/* queue a sequence of bits to clock out TDI / in TDO, executing if the buffer is full.
 *
 * sequence=NULL means clock out zeros on TDI
 * tdo_buffer=NULL means don't capture TDO
 */
static void cmsis_dap_add_jtag_sequence(int s_len, const uint8_t *sequence, int s_offset,
                    bool tms, uint8_t *tdo_buffer, int tdo_buffer_offset)
{
    DEBUG_JTAG_IO("[at %d] %d bits, tms %s, seq offset %d, tdo buf %p, tdo offset %d",
        queued_seq_buf_end,
        s_len, tms ? "HIGH" : "LOW", s_offset, tdo_buffer, tdo_buffer_offset);

    if (s_len == 0)
        return;

    if (s_len > 64) {
        DEBUG_JTAG_IO("START JTAG SEQ SPLIT");
        for (int offset = 0; offset < s_len; offset += 64) {
            int len = s_len - offset;
            if (len > 64)
                len = 64;
            DEBUG_JTAG_IO("Splitting long jtag sequence: %d-bit chunk starting at offset %d", len, offset);
            cmsis_dap_add_jtag_sequence(
                len,
                sequence,
                s_offset + offset,
                tms,
                tdo_buffer,
                tdo_buffer == NULL ? 0 : (tdo_buffer_offset + offset)
                );
        }
        DEBUG_JTAG_IO("END JTAG SEQ SPLIT");
        return;
    }

    int cmd_len = 1 + DIV_ROUND_UP(s_len, 8);
    if (queued_seq_count >= 255 || queued_seq_buf_end + cmd_len > QUEUED_SEQ_BUF_LEN)
        /* empty out the buffer */
        cmsis_dap_flush();

    ++queued_seq_count;

    /* control byte */
    queued_seq_buf[queued_seq_buf_end] =
        (tms ? DAP_JTAG_SEQ_TMS : 0) |
        (tdo_buffer != NULL ? DAP_JTAG_SEQ_TDO : 0) |
        (s_len == 64 ? 0 : s_len);

    if (sequence != NULL)
        bit_copy(&queued_seq_buf[queued_seq_buf_end + 1], 0, sequence, s_offset, s_len);
    else
        memset(&queued_seq_buf[queued_seq_buf_end + 1], 0, DIV_ROUND_UP(s_len, 8));

    queued_seq_buf_end += cmd_len;

    if (tdo_buffer != NULL) {
        struct pending_scan_result *scan = &pending_scan_results[pending_scan_result_count++];
        scan->first = queued_seq_tdo_ptr;
        queued_seq_tdo_ptr += DIV_ROUND_UP(s_len, 8);
        scan->length = s_len;
        scan->buffer = tdo_buffer;
        scan->buffer_offset = tdo_buffer_offset;
    }
}

/* queue a sequence of bits to clock out TMS, executing if the buffer is full */
static void cmsis_dap_add_tms_sequence(const uint8_t *sequence, int s_len)
{
    DEBUG_JTAG_IO("%d bits: %02X", s_len, *sequence);
    /* we use a series of CMD_DAP_JTAG_SEQ commands to toggle TMS,
       because even though it seems ridiculously inefficient, it
       allows us to combine TMS and scan sequences into the same
       USB packet. */
    /* TODO: combine runs of the same tms value */
    for (int i = 0; i < s_len; ++i) {
        bool bit = (sequence[i / 8] & (1 << (i % 8))) != 0;
        cmsis_dap_add_jtag_sequence(1, NULL, 0, bit, NULL, 0);
    }
}

/* Move to the end state by queuing a sequence to clock into TMS */
static void cmsis_dap_state_move(void)
{
    uint8_t tms_scan;
    uint8_t tms_scan_bits;

    tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
    tms_scan_bits = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());

    DEBUG_JTAG_IO("state move from %s to %s: %d clocks, %02X on tms",
        tap_state_name(tap_get_state()), tap_state_name(tap_get_end_state()),
        tms_scan_bits, tms_scan);
    cmsis_dap_add_tms_sequence(&tms_scan, tms_scan_bits);

    tap_set_state(tap_get_end_state());
}


/* Execute a JTAG scan operation by queueing TMS and TDI/TDO sequences */
static void cmsis_dap_execute_scan(struct jtag_command *cmd)
{
    DEBUG_JTAG_IO("%s type:%d", cmd->cmd.scan->ir_scan ? "IRSCAN" : "DRSCAN",
        jtag_scan_type(cmd->cmd.scan));

    /* Make sure there are no trailing fields with num_bits == 0, or the logic below will fail. */
    while (cmd->cmd.scan->num_fields > 0
            && cmd->cmd.scan->fields[cmd->cmd.scan->num_fields - 1].num_bits == 0) {
        cmd->cmd.scan->num_fields--;
        LOG_DEBUG("discarding trailing empty field");
    }

    if (cmd->cmd.scan->num_fields == 0) {
        LOG_DEBUG("empty scan, doing nothing");
        return;
    }

    if (cmd->cmd.scan->ir_scan) {
        if (tap_get_state() != TAP_IRSHIFT) {
            cmsis_dap_end_state(TAP_IRSHIFT);
            cmsis_dap_state_move();
        }
    } else {
        if (tap_get_state() != TAP_DRSHIFT) {
            cmsis_dap_end_state(TAP_DRSHIFT);
            cmsis_dap_state_move();
        }
    }

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

    struct scan_field *field = cmd->cmd.scan->fields;
    unsigned scan_size = 0;

    for (int i = 0; i < cmd->cmd.scan->num_fields; i++, field++) {
        scan_size += field->num_bits;
        DEBUG_JTAG_IO("%s%s field %d/%d %d bits",
            field->in_value ? "in" : "",
            field->out_value ? "out" : "",
            i,
            cmd->cmd.scan->num_fields,
            field->num_bits);

        if (i == cmd->cmd.scan->num_fields - 1 && tap_get_state() != tap_get_end_state()) {
            DEBUG_JTAG_IO("Last field and have to move out of SHIFT state");
            /* Last field, and we're leaving IRSHIFT/DRSHIFT. Clock last bit during tap
             * movement. This last field can't have length zero, it was checked above. */
            cmsis_dap_add_jtag_sequence(
                field->num_bits - 1, /* number of bits to clock */
                field->out_value, /* output sequence */
                0, /* output offset */
                false, /* TMS low */
                field->in_value,
                0);

            /* Clock the last bit out, with TMS high */
            uint8_t last_bit = 0;
            if (field->out_value)
                bit_copy(&last_bit, 0, field->out_value, field->num_bits - 1, 1);
            cmsis_dap_add_jtag_sequence(
                1,
                &last_bit,
                0,
                true,
                field->in_value,
                field->num_bits - 1);
            tap_set_state(tap_state_transition(tap_get_state(), 1));

            /* Now clock one more cycle, with TMS low, to get us into a PAUSE state */
            cmsis_dap_add_jtag_sequence(
                1,
                &last_bit,
                0,
                false,
                NULL,
                0);
            tap_set_state(tap_state_transition(tap_get_state(), 0));
        } else {
            DEBUG_JTAG_IO("Internal field, staying in SHIFT state afterwards");
            /* Clocking part of a sequence into DR or IR with TMS=0,
               leaving TMS=0 at the end so we can continue later */
            cmsis_dap_add_jtag_sequence(
                field->num_bits,
                field->out_value,
                0,
                false,
                field->in_value,
                0);
        }
    }

    if (tap_get_state() != tap_get_end_state()) {
        cmsis_dap_end_state(tap_get_end_state());
        cmsis_dap_state_move();
    }

    DEBUG_JTAG_IO("%s scan, %i bits, end in %s",
        (cmd->cmd.scan->ir_scan) ? "IR" : "DR", scan_size,
        tap_state_name(tap_get_end_state()));
}

static void cmsis_dap_pathmove(int num_states, tap_state_t *path)
{
    int i;
    uint8_t tms0 = 0x00;
    uint8_t tms1 = 0xff;

    for (i = 0; i < num_states; i++) {
        if (path[i] == tap_state_transition(tap_get_state(), false))
            cmsis_dap_add_tms_sequence(&tms0, 1);
        else if (path[i] == tap_state_transition(tap_get_state(), true))
            cmsis_dap_add_tms_sequence(&tms1, 1);
        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]);
    }

    cmsis_dap_end_state(tap_get_state());
}

static void cmsis_dap_execute_pathmove(struct jtag_command *cmd)
{
    DEBUG_JTAG_IO("pathmove: %i states, end in %i",
              cmd->cmd.pathmove->num_states,
           cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]);

    cmsis_dap_pathmove(cmd->cmd.pathmove->num_states, cmd->cmd.pathmove->path);
}

static void cmsis_dap_stableclocks(int num_cycles)
{
    int i;

    uint8_t tms = tap_get_state() == TAP_RESET;
    /* TODO: Perform optimizations? */
    /* Execute num_cycles. */
    for (i = 0; i < num_cycles; i++)
        cmsis_dap_add_tms_sequence(&tms, 1);
}

static void cmsis_dap_runtest(int num_cycles)
{
    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) {
        cmsis_dap_end_state(TAP_IDLE);
        cmsis_dap_state_move();
    }
    cmsis_dap_stableclocks(num_cycles);

    /* Finish in end_state. */
    cmsis_dap_end_state(saved_end_state);

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

static void cmsis_dap_execute_runtest(struct jtag_command *cmd)
{
    DEBUG_JTAG_IO("runtest %i cycles, end in %i", cmd->cmd.runtest->num_cycles,
              cmd->cmd.runtest->end_state);

    cmsis_dap_end_state(cmd->cmd.runtest->end_state);
    cmsis_dap_runtest(cmd->cmd.runtest->num_cycles);
}

static void cmsis_dap_execute_stableclocks(struct jtag_command *cmd)
{
    DEBUG_JTAG_IO("stableclocks %i cycles", cmd->cmd.runtest->num_cycles);
    cmsis_dap_stableclocks(cmd->cmd.runtest->num_cycles);
}

/* TODO: Is there need to call cmsis_dap_flush() for the JTAG_PATHMOVE,
 * JTAG_RUNTEST, JTAG_STABLECLOCKS? */
static void cmsis_dap_execute_command(struct jtag_command *cmd)
{
    switch (cmd->type) {
        case JTAG_RESET:
            cmsis_dap_flush();
            cmsis_dap_execute_reset(cmd);
            break;
        case JTAG_SLEEP:
            cmsis_dap_flush();
            cmsis_dap_execute_sleep(cmd);
            break;
        case JTAG_TLR_RESET:
            cmsis_dap_flush();
            cmsis_dap_execute_tlr_reset(cmd);
            break;
        case JTAG_SCAN:
            cmsis_dap_execute_scan(cmd);
            break;
        case JTAG_PATHMOVE:
            cmsis_dap_execute_pathmove(cmd);
            break;
        case JTAG_RUNTEST:
            cmsis_dap_execute_runtest(cmd);
            break;
        case JTAG_STABLECLOCKS:
            cmsis_dap_execute_stableclocks(cmd);
            break;
        case JTAG_TMS:
        default:
            LOG_ERROR("BUG: unknown JTAG command type 0x%X encountered", cmd->type);
            exit(-1);
    }
}

static int cmsis_dap_execute_queue(void)
{
    struct jtag_command *cmd = jtag_command_queue;

    while (cmd != NULL) {
        cmsis_dap_execute_command(cmd);
        cmd = cmd->next;
    }

    cmsis_dap_flush();

    return ERROR_OK;
}

static int cmsis_dap_speed(int speed)
{
    if (speed > DAP_MAX_CLOCK) {
        LOG_INFO("reduce speed request: %dkHz to %dkHz maximum", speed, DAP_MAX_CLOCK);
        speed = DAP_MAX_CLOCK;
    }

    if (speed == 0) {
        LOG_INFO("RTCK not supported");
        return ERROR_JTAG_NOT_IMPLEMENTED;
    }

    return cmsis_dap_cmd_DAP_SWJ_Clock(speed);
}

static int cmsis_dap_speed_div(int speed, int *khz)
{
    *khz = speed;
    return ERROR_OK;
}

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

static int_least32_t cmsis_dap_swd_frequency(int_least32_t hz)
{
    if (hz > 0)
        cmsis_dap_speed(hz / 1000);

    return hz;
}


COMMAND_HANDLER(cmsis_dap_handle_info_command)
{
    if (cmsis_dap_get_version_info() == ERROR_OK)
        cmsis_dap_get_status();

    return ERROR_OK;
}

COMMAND_HANDLER(cmsis_dap_handle_vid_pid_command)
{
    if (CMD_ARGC > MAX_USB_IDS * 2) {
        LOG_WARNING("ignoring extra IDs in cmsis_dap_vid_pid "
            "(maximum is %d pairs)", MAX_USB_IDS);
        CMD_ARGC = MAX_USB_IDS * 2;
    }
    if (CMD_ARGC < 2 || (CMD_ARGC & 1)) {
        LOG_WARNING("incomplete cmsis_dap_vid_pid configuration directive");
        if (CMD_ARGC < 2)
            return ERROR_COMMAND_SYNTAX_ERROR;
        /* remove the incomplete trailing id */
        CMD_ARGC -= 1;
    }

    unsigned i;
    for (i = 0; i < CMD_ARGC; i += 2) {
        COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i], cmsis_dap_vid[i >> 1]);
        COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i + 1], cmsis_dap_pid[i >> 1]);
    }

    /*
     * Explicitly terminate, in case there are multiples instances of
     * cmsis_dap_vid_pid.
     */
    cmsis_dap_vid[i >> 1] = cmsis_dap_pid[i >> 1] = 0;

    return ERROR_OK;
}

COMMAND_HANDLER(cmsis_dap_handle_serial_command)
{
    if (CMD_ARGC == 1) {
        size_t len = mbstowcs(NULL, CMD_ARGV[0], 0);
        cmsis_dap_serial = calloc(len + 1, sizeof(wchar_t));
        if (cmsis_dap_serial == NULL) {
            LOG_ERROR("unable to allocate memory");
            return ERROR_OK;
        }
        if (mbstowcs(cmsis_dap_serial, CMD_ARGV[0], len + 1) == (size_t)-1) {
            free(cmsis_dap_serial);
            cmsis_dap_serial = NULL;
            LOG_ERROR("unable to convert serial");
        }
    } else {
        LOG_ERROR("expected exactly one argument to cmsis_dap_serial <serial-number>");
    }

    return ERROR_OK;
}

static const struct command_registration cmsis_dap_subcommand_handlers[] = {
    {
        .name = "info",
        .handler = &cmsis_dap_handle_info_command,
        .mode = COMMAND_EXEC,
        .usage = "",
        .help = "show cmsis-dap info",
    },
    COMMAND_REGISTRATION_DONE
};

static const struct command_registration cmsis_dap_command_handlers[] = {
    {
        .name = "cmsis-dap",
        .mode = COMMAND_ANY,
        .help = "perform CMSIS-DAP management",
        .usage = "<cmd>",
        .chain = cmsis_dap_subcommand_handlers,
    },
    {
        .name = "cmsis_dap_vid_pid",
        .handler = &cmsis_dap_handle_vid_pid_command,
        .mode = COMMAND_CONFIG,
        .help = "the vendor ID and product ID of the CMSIS-DAP device",
        .usage = "(vid pid)* ",
    },
    {
        .name = "cmsis_dap_serial",
        .handler = &cmsis_dap_handle_serial_command,
        .mode = COMMAND_CONFIG,
        .help = "set the serial number of the adapter",
        .usage = "serial_string",
    },
    COMMAND_REGISTRATION_DONE
};

static const struct swd_driver cmsis_dap_swd_driver = {
    .init = cmsis_dap_swd_init,
    .frequency = cmsis_dap_swd_frequency,
    .switch_seq = cmsis_dap_swd_switch_seq,
    .read_reg = cmsis_dap_swd_read_reg,
    .write_reg = cmsis_dap_swd_write_reg,
    .run = cmsis_dap_swd_run_queue,
};

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

struct jtag_interface cmsis_dap_interface = {
    .name = "cmsis-dap",
    .commands = cmsis_dap_command_handlers,
    .swd = &cmsis_dap_swd_driver,
    .transports = cmsis_dap_transport,

    .execute_queue = cmsis_dap_execute_queue,
    .speed = cmsis_dap_speed,
    .speed_div = cmsis_dap_speed_div,
    .khz = cmsis_dap_khz,
    .init = cmsis_dap_init,
    .quit = cmsis_dap_quit,
};