[openocd.git] / src / jtag / drivers / cmsis_dap.c

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

/***************************************************************************
 *   Copyright (C) 2021 by Adrian Negreanu                                 *
 *   groleo@gmail.com                                                      *
 *                                                                         *
 *   Copyright (C) 2018 by Mickaël Thomas                                  *
 *   mickael9@gmail.com                                                    *
 *                                                                         *
 *   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                                                  *
 ***************************************************************************/

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

#include <transport/transport.h>
#include "helper/replacements.h"
#include <jtag/adapter.h>
#include <jtag/swd.h>
#include <jtag/interface.h>
#include <jtag/commands.h>
#include <jtag/tcl.h>
#include <target/cortex_m.h>

#include "cmsis_dap.h"
#include "libusb_helper.h"

static const struct cmsis_dap_backend *const cmsis_dap_backends[] = {
#if BUILD_CMSIS_DAP_USB == 1
        &cmsis_dap_usb_backend,
#endif

#if BUILD_CMSIS_DAP_HID == 1
        &cmsis_dap_hid_backend,
#endif
};

/* 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
 * PID 0x2750: Keil ULINKplus 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 int cmsis_dap_backend = -1;
static bool swd_mode;

/* 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_VENDOR            0x01      /* string */
#define INFO_ID_PRODUCT           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_ID_SWO_BUF_SZ        0xfd      /* word */

#define INFO_CAPS_SWD                 BIT(0)
#define INFO_CAPS_JTAG                BIT(1)
#define INFO_CAPS_SWO_UART            BIT(2)
#define INFO_CAPS_SWO_MANCHESTER      BIT(3)
#define INFO_CAPS_ATOMIC_CMDS         BIT(4)
#define INFO_CAPS_TEST_DOMAIN_TIMER   BIT(5)
#define INFO_CAPS_SWO_STREAMING_TRACE BIT(6)
#define INFO_CAPS_UART_PORT           BIT(7)
#define INFO_CAPS_USB_COM_PORT        BIT(8)
#define INFO_CAPS__NUM_CAPS               9

/* 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
#define CMD_DAP_SWD_SEQUENCE      0x1D

/* 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 SWO Commands */
#define CMD_DAP_SWO_TRANSPORT     0x17
#define CMD_DAP_SWO_MODE          0x18
#define CMD_DAP_SWO_BAUDRATE      0x19
#define CMD_DAP_SWO_CONTROL       0x1A
#define CMD_DAP_SWO_STATUS        0x1B
#define CMD_DAP_SWO_DATA          0x1C
#define CMD_DAP_SWO_EX_STATUS     0x1E

/* SWO transport mode for reading trace data */
#define DAP_SWO_TRANSPORT_NONE    0
#define DAP_SWO_TRANSPORT_DATA    1
#define DAP_SWO_TRANSPORT_WINUSB  2

/* SWO trace capture mode */
#define DAP_SWO_MODE_OFF          0
#define DAP_SWO_MODE_UART         1
#define DAP_SWO_MODE_MANCHESTER   2

/* SWO trace data capture */
#define DAP_SWO_CONTROL_STOP      0
#define DAP_SWO_CONTROL_START     1

/* SWO trace status */
#define DAP_SWO_STATUS_CAPTURE_INACTIVE      0
#define DAP_SWO_STATUS_CAPTURE_ACTIVE        1
#define DAP_SWO_STATUS_CAPTURE_MASK          BIT(0)
#define DAP_SWO_STATUS_STREAM_ERROR_MASK     BIT(6)
#define DAP_SWO_STATUS_BUFFER_OVERRUN_MASK   BIT(7)

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

static const char * const info_caps_str[INFO_CAPS__NUM_CAPS] = {
        "SWD supported",
        "JTAG supported",
        "SWO-UART supported",
        "SWO-MANCHESTER supported",
        "Atomic commands supported",
        "Test domain timer supported",
        "SWO streaming trace supported",
        "UART communication port supported",
        "UART via USB COM port supported",
};

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

struct pending_request_block {
        struct pending_transfer_result *transfers;
        int transfer_count;
};

struct pending_scan_result {
        /** Offset in bytes in the CMD_DAP_JTAG_SEQ response buffer. */
        unsigned first;
        /** Number of bits to read. */
        unsigned length;
        /** Location to store the result */
        uint8_t *buffer;
        /** Offset in the destination buffer */
        unsigned buffer_offset;
};

/* Up to MIN(packet_count, MAX_PENDING_REQUESTS) requests may be issued
 * until the first response arrives */
#define MAX_PENDING_REQUESTS 3

/* Pending requests are organized as a FIFO - circular buffer */
/* Each block in FIFO can contain up to pending_queue_len transfers */
static int pending_queue_len;
static struct pending_request_block pending_fifo[MAX_PENDING_REQUESTS];
static int pending_fifo_put_idx, pending_fifo_get_idx;
static int pending_fifo_block_count;

/* 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 uint8_t output_pins = SWJ_PIN_SRST | SWJ_PIN_TRST;

static struct cmsis_dap *cmsis_dap_handle;


static int cmsis_dap_quit(void);

static int cmsis_dap_open(void)
{
        const struct cmsis_dap_backend *backend = NULL;

        struct cmsis_dap *dap = calloc(1, sizeof(struct cmsis_dap));
        if (!dap) {
                LOG_ERROR("unable to allocate memory");
                return ERROR_FAIL;
        }

        if (cmsis_dap_backend >= 0) {
                /* Use forced backend */
                backend = cmsis_dap_backends[cmsis_dap_backend];
                if (backend->open(dap, cmsis_dap_vid, cmsis_dap_pid, adapter_get_required_serial()) != ERROR_OK)
                        backend = NULL;
        } else {
                /* Try all backends */
                for (unsigned int i = 0; i < ARRAY_SIZE(cmsis_dap_backends); i++) {
                        backend = cmsis_dap_backends[i];
                        if (backend->open(dap, cmsis_dap_vid, cmsis_dap_pid, adapter_get_required_serial()) == ERROR_OK)
                                break;
                        else
                                backend = NULL;
                }
        }

        if (!backend) {
                LOG_ERROR("unable to find a matching CMSIS-DAP device");
                free(dap);
                return ERROR_FAIL;
        }

        dap->backend = backend;

        cmsis_dap_handle = dap;

        return ERROR_OK;
}

static void cmsis_dap_close(struct cmsis_dap *dap)
{
        if (dap->backend) {
                dap->backend->close(dap);
                dap->backend = NULL;
        }

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

        for (int i = 0; i < MAX_PENDING_REQUESTS; i++) {
                free(pending_fifo[i].transfers);
                pending_fifo[i].transfers = NULL;
        }
}

static void cmsis_dap_flush_read(struct cmsis_dap *dap)
{
        unsigned int i;
        /* Some CMSIS-DAP adapters keep buffered packets over
         * USB close/open so we need to flush up to 64 old packets
         * to be sure all buffers are empty */
        for (i = 0; i < 64; i++) {
                int retval = dap->backend->read(dap, 10);
                if (retval == ERROR_TIMEOUT_REACHED)
                        break;
        }
        if (i)
                LOG_DEBUG("Flushed %u packets", i);
}

/* Send a message and receive the reply */
static int cmsis_dap_xfer(struct cmsis_dap *dap, int txlen)
{
        if (pending_fifo_block_count) {
                LOG_ERROR("pending %d blocks, flushing", pending_fifo_block_count);
                while (pending_fifo_block_count) {
                        dap->backend->read(dap, 10);
                        pending_fifo_block_count--;
                }
                pending_fifo_put_idx = 0;
                pending_fifo_get_idx = 0;
        }

        uint8_t current_cmd = cmsis_dap_handle->command[0];
        int retval = dap->backend->write(dap, txlen, LIBUSB_TIMEOUT_MS);
        if (retval < 0)
                return retval;

        /* get reply */
        retval = dap->backend->read(dap, LIBUSB_TIMEOUT_MS);
        if (retval < 0)
                return retval;

        uint8_t *resp = cmsis_dap_handle->response;
        if (resp[0] == DAP_ERROR) {
                LOG_ERROR("CMSIS-DAP command 0x%" PRIx8 " not implemented", current_cmd);
                return ERROR_NOT_IMPLEMENTED;
        }

        if (resp[0] != current_cmd) {
                LOG_ERROR("CMSIS-DAP command mismatch. Sent 0x%" PRIx8
                         " received 0x%" PRIx8, current_cmd, resp[0]);

                cmsis_dap_flush_read(dap);
                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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWJ_PINS;
        command[1] = pins;
        command[2] = mask;
        h_u32_to_le(&command[3], delay);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 7);
        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DAP_SWJ_PINS failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (input)
                *input = cmsis_dap_handle->response[1];

        return ERROR_OK;
}

static int cmsis_dap_cmd_dap_swj_clock(uint32_t swj_clock)
{
        uint8_t *command = cmsis_dap_handle->command;

        /* set clock in Hz */
        swj_clock *= 1000;

        command[0] = CMD_DAP_SWJ_CLOCK;
        h_u32_to_le(&command[1], swj_clock);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 5);
        if (retval != ERROR_OK || cmsis_dap_handle->response[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)
{
        uint8_t *command = cmsis_dap_handle->command;

#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

        command[0] = CMD_DAP_SWJ_SEQ;
        command[1] = s_len;
        bit_copy(&command[2], 0, sequence, 0, s_len);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2 + DIV_ROUND_UP(s_len, 8));
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK)
                return ERROR_FAIL;

        return ERROR_OK;
}

static int cmsis_dap_cmd_dap_info(uint8_t info, uint8_t **data)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_INFO;
        command[1] = info;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_INFO failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        *data = &cmsis_dap_handle->response[1];

        return ERROR_OK;
}

static int cmsis_dap_cmd_dap_led(uint8_t led, uint8_t state)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_LED;
        command[1] = led;
        command[2] = state;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 3);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_CONNECT;
        command[1] = mode;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_CONNECT failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (cmsis_dap_handle->response[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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_DISCONNECT;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 1);
        if (retval != ERROR_OK || cmsis_dap_handle->response[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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_TFER_CONFIGURE;
        command[1] = idle;
        h_u16_to_le(&command[2], retry_count);
        h_u16_to_le(&command[4], match_retry);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 6);
        if (retval != ERROR_OK || cmsis_dap_handle->response[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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWD_CONFIGURE;
        command[1] = cfg;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK || cmsis_dap_handle->response[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)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_DELAY;
        h_u16_to_le(&command[1], delay_us);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 3);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_Delay failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}
#endif

static int cmsis_dap_metacmd_targetsel(uint32_t instance_id)
{
        uint8_t *command = cmsis_dap_handle->command;
        const uint32_t SEQ_RD = 0x80, SEQ_WR = 0x00;

        /* SWD multi-drop requires a transfer ala CMD_DAP_TFER,
        but with no expectation of an SWD ACK response.  In
        CMSIS-DAP v1.20 and v2.00, CMD_DAP_SWD_SEQUENCE was
        added to allow this special sequence to be generated.
        The purpose of this operation is to select the target
        corresponding to the instance_id that is written */

        LOG_DEBUG_IO("DP write reg TARGETSEL %" PRIx32, instance_id);

        size_t idx = 0;
        command[idx++] = CMD_DAP_SWD_SEQUENCE;
        command[idx++] = 3;     /* sequence count */

        /* sequence 0: packet request for TARGETSEL */
        command[idx++] = SEQ_WR | 8;
        command[idx++] = SWD_CMD_START | swd_cmd(false, false, DP_TARGETSEL) | SWD_CMD_STOP | SWD_CMD_PARK;

        /* sequence 1: read Trn ACK Trn, no expectation for target to ACK  */
        command[idx++] = SEQ_RD | 5;

        /* sequence 2: WDATA plus parity */
        command[idx++] = SEQ_WR | (32 + 1);
        h_u32_to_le(command + idx, instance_id);
        idx += 4;
        command[idx++] = parity_u32(instance_id);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, idx);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command SWD_Sequence failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/**
 * Sets the SWO transport mode.
 * @param[in] transport     The transport mode. Can be None, SWO_Data or
 *                          WinUSB (requires CMSIS-DAP v2).
 */
static int cmsis_dap_cmd_dap_swo_transport(uint8_t transport)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_TRANSPORT;
        command[1] = transport;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Transport(%d) failed.", transport);
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/**
 * Sets the SWO trace capture mode.
 * @param[in] mode          Trace capture mode. Can be UART or MANCHESTER.
 */
static int cmsis_dap_cmd_dap_swo_mode(uint8_t mode)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_MODE;
        command[1] = mode;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Mode(%d) failed.", mode);
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/**
 * Sets the baudrate for capturing SWO trace data.
 * Can be called iteratively to determine supported baudrates.
 * @param[in]  in_baudrate  Requested baudrate.
 * @param[out] dev_baudrate Actual baudrate or 0 (baudrate not configured).
 *                          When requested baudrate is not achievable the
 *                          closest configured baudrate can be returned or
 *                          0 which indicates that baudrate was not configured.
 */
static int cmsis_dap_cmd_dap_swo_baudrate(
                                        uint32_t in_baudrate,
                                        uint32_t *dev_baudrate)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_BAUDRATE;
        h_u32_to_le(&command[1], in_baudrate);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 5);
        uint32_t rvbr = le_to_h_u32(&cmsis_dap_handle->response[1]);
        if (retval != ERROR_OK || rvbr == 0) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Baudrate(%u) -> %u failed.", in_baudrate, rvbr);
                if (dev_baudrate)
                        *dev_baudrate = 0;
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (dev_baudrate)
                *dev_baudrate = rvbr;

        return ERROR_OK;
}

/**
 * Controls the SWO trace data capture.
 * @param[in] control       Start or stop a trace. Starting capture automatically
 *                          flushes any existing trace data in buffers which has
 *                          not yet been read.
 */
static int cmsis_dap_cmd_dap_swo_control(uint8_t control)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_CONTROL;
        command[1] = control;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 2);
        if (retval != ERROR_OK || cmsis_dap_handle->response[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Control(%d) failed.", control);
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/**
 * Reads the SWO trace status.
 * @param[out] trace_status The trace's status.
 *                          Bit0: Trace Capture (1 - active, 0 - inactive).
 *                          Bit6: Trace Stream Error.
 *                          Bit7: Trace Buffer Overrun.
 * @param[out] trace_count  Number of bytes in Trace Buffer (not yet read).
 */
static int cmsis_dap_cmd_dap_swo_status(
                                        uint8_t *trace_status,
                                        size_t *trace_count)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_STATUS;

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 1);
        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Status failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (trace_status)
                *trace_status = cmsis_dap_handle->response[1];
        if (trace_count)
                *trace_count = le_to_h_u32(&cmsis_dap_handle->response[2]);

        return ERROR_OK;
}

/**
 * Reads the captured SWO trace data from Trace Buffer.
 * @param[in]  max_trace_count Maximum number of Trace Data bytes to read.
 * @param[out] trace_status The trace's status.
 * @param[out] trace_count  Number of Trace Data bytes read.
 * @param[out] data         Trace Data bytes read.
 */
static int cmsis_dap_cmd_dap_swo_data(
                                        size_t max_trace_count,
                                        uint8_t *trace_status,
                                        size_t *trace_count,
                                        uint8_t *data)
{
        uint8_t *command = cmsis_dap_handle->command;

        command[0] = CMD_DAP_SWO_DATA;
        h_u16_to_le(&command[1], max_trace_count);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, 3);
        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP: command CMD_SWO_Data failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        *trace_status = cmsis_dap_handle->response[1];
        *trace_count = le_to_h_u16(&cmsis_dap_handle->response[2]);

        if (*trace_count > 0)
                memcpy(data, &cmsis_dap_handle->response[4], *trace_count);

        return ERROR_OK;
}

static void cmsis_dap_swd_write_from_queue(struct cmsis_dap *dap)
{
        uint8_t *command = cmsis_dap_handle->command;
        struct pending_request_block *block = &pending_fifo[pending_fifo_put_idx];

        LOG_DEBUG_IO("Executing %d queued transactions from FIFO index %d", block->transfer_count, pending_fifo_put_idx);

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

        if (block->transfer_count == 0)
                goto skip;

        command[0] = CMD_DAP_TFER;
        command[1] = 0x00;      /* DAP Index */
        command[2] = block->transfer_count;
        size_t idx = 3;

        for (int i = 0; i < block->transfer_count; i++) {
                struct pending_transfer_result *transfer = &(block->transfers[i]);
                uint8_t cmd = transfer->cmd;
                uint32_t data = transfer->data;

                LOG_DEBUG_IO("%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;
                }

                command[idx++] = (cmd >> 1) & 0x0f;
                if (!(cmd & SWD_CMD_RNW)) {
                        h_u32_to_le(&command[idx], data);
                        idx += 4;
                }
        }

        int retval = dap->backend->write(dap, idx, LIBUSB_TIMEOUT_MS);
        if (retval < 0) {
                queued_retval = retval;
                goto skip;
        } else {
                queued_retval = ERROR_OK;
        }

        pending_fifo_put_idx = (pending_fifo_put_idx + 1) % dap->packet_count;
        pending_fifo_block_count++;
        if (pending_fifo_block_count > dap->packet_count)
                LOG_ERROR("too much pending writes %d", pending_fifo_block_count);

        return;

skip:
        block->transfer_count = 0;
}

static void cmsis_dap_swd_read_process(struct cmsis_dap *dap, int timeout_ms)
{
        struct pending_request_block *block = &pending_fifo[pending_fifo_get_idx];

        if (pending_fifo_block_count == 0)
                LOG_ERROR("no pending write");

        /* get reply */
        int retval = dap->backend->read(dap, timeout_ms);
        if (retval == ERROR_TIMEOUT_REACHED && timeout_ms < LIBUSB_TIMEOUT_MS)
                return;

        if (retval <= 0) {
                LOG_DEBUG("error reading data");
                queued_retval = ERROR_FAIL;
                goto skip;
        }

        uint8_t *resp = dap->response;
        if (resp[0] != CMD_DAP_TFER) {
                LOG_ERROR("CMSIS-DAP command mismatch. Expected 0x%x received 0x%" PRIx8,
                        CMD_DAP_TFER, resp[0]);
                queued_retval = ERROR_FAIL;
                goto skip;
        }

        uint8_t transfer_count = resp[1];
        uint8_t ack = resp[2] & 0x07;
        if (resp[2] & 0x08) {
                LOG_DEBUG("CMSIS-DAP Protocol Error @ %d (wrong parity)", transfer_count);
                queued_retval = ERROR_FAIL;
                goto skip;
        }
        if (ack != SWD_ACK_OK) {
                LOG_DEBUG("SWD ack not OK @ %d %s", transfer_count,
                          ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK");
                queued_retval = ack == SWD_ACK_WAIT ? ERROR_WAIT : ERROR_FAIL;
                /* TODO: use results of transfers completed before the error occurred? */
                goto skip;
        }

        if (block->transfer_count != transfer_count)
                LOG_ERROR("CMSIS-DAP transfer count mismatch: expected %d, got %d",
                          block->transfer_count, transfer_count);

        LOG_DEBUG_IO("Received results of %d queued transactions FIFO index %d",
                 transfer_count, pending_fifo_get_idx);
        size_t idx = 3;
        for (int i = 0; i < transfer_count; i++) {
                struct pending_transfer_result *transfer = &(block->transfers[i]);
                if (transfer->cmd & SWD_CMD_RNW) {
                        static uint32_t last_read;
                        uint32_t data = le_to_h_u32(&resp[idx]);
                        uint32_t tmp = data;
                        idx += 4;

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

                        /* Imitate posted AP reads */
                        if ((transfer->cmd & SWD_CMD_APNDP) ||
                            ((transfer->cmd & SWD_CMD_A32) >> 1 == DP_RDBUFF)) {
                                tmp = last_read;
                                last_read = data;
                        }

                        if (transfer->buffer)
                                *(uint32_t *)(transfer->buffer) = tmp;
                }
        }

skip:
        block->transfer_count = 0;
        pending_fifo_get_idx = (pending_fifo_get_idx + 1) % dap->packet_count;
        pending_fifo_block_count--;
}

static int cmsis_dap_swd_run_queue(void)
{
        if (pending_fifo_block_count)
                cmsis_dap_swd_read_process(cmsis_dap_handle, 0);

        cmsis_dap_swd_write_from_queue(cmsis_dap_handle);

        while (pending_fifo_block_count)
                cmsis_dap_swd_read_process(cmsis_dap_handle, LIBUSB_TIMEOUT_MS);

        pending_fifo_put_idx = 0;
        pending_fifo_get_idx = 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)
{
        bool targetsel_cmd = swd_cmd(false, false, DP_TARGETSEL) == cmd;

        if (pending_fifo[pending_fifo_put_idx].transfer_count == pending_queue_len
                         || targetsel_cmd) {
                if (pending_fifo_block_count)
                        cmsis_dap_swd_read_process(cmsis_dap_handle, 0);

                /* Not enough room in the queue. Run the queue. */
                cmsis_dap_swd_write_from_queue(cmsis_dap_handle);

                if (pending_fifo_block_count >= cmsis_dap_handle->packet_count)
                        cmsis_dap_swd_read_process(cmsis_dap_handle, LIBUSB_TIMEOUT_MS);
        }

        if (queued_retval != ERROR_OK)
                return;

        if (targetsel_cmd) {
                cmsis_dap_metacmd_targetsel(data);
                return;
        }

        struct pending_request_block *block = &pending_fifo[pending_fifo_put_idx];
        struct pending_transfer_result *transfer = &(block->transfers[block->transfer_count]);
        transfer->data = data;
        transfer->cmd = cmd;
        if (cmd & SWD_CMD_RNW) {
                /* Queue a read transaction */
                transfer->buffer = dst;
        }
        block->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_serial_info(void)
{
        uint8_t *data;

        int retval = cmsis_dap_cmd_dap_info(INFO_ID_SERNUM, &data);
        if (retval != ERROR_OK)
                return retval;

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

        return ERROR_OK;
}

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 || data[0] == 2) {
                uint16_t caps = data[1];
                if (data[0] == 2)
                        caps |= (uint16_t)data[2] << 8;

                cmsis_dap_handle->caps = caps;

                for (int i = 0; i < INFO_CAPS__NUM_CAPS; ++i) {
                        if (caps & BIT(i))
                                LOG_INFO("CMSIS-DAP: %s", info_caps_str[i]);
                }
        }

        return ERROR_OK;
}

static int cmsis_dap_get_swo_buf_sz(uint32_t *swo_buf_sz)
{
        uint8_t *data;

        /* INFO_ID_SWO_BUF_SZ - word */
        int retval = cmsis_dap_cmd_dap_info(INFO_ID_SWO_BUF_SZ, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0] != 4)
                return ERROR_FAIL;

        *swo_buf_sz = le_to_h_u32(&data[1]);

        LOG_INFO("CMSIS-DAP: SWO Trace Buffer Size = %u bytes", *swo_buf_sz);

        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;

        if ((output_pins & (SWJ_PIN_SRST | SWJ_PIN_TRST)) == (SWJ_PIN_SRST | SWJ_PIN_TRST)) {
                /* Following workaround deasserts reset on most adapters.
                 * Do not reconnect if a reset line is active!
                 * Reconnecting would break connecting under reset. */

                /* 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(CONNECT_SWD);
                if (retval != ERROR_OK)
                        return retval;
        }

        switch (seq) {
        case LINE_RESET:
                LOG_DEBUG_IO("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 JTAG_TO_DORMANT:
                LOG_DEBUG("JTAG-to-DORMANT");
                s = swd_seq_jtag_to_dormant;
                s_len = swd_seq_jtag_to_dormant_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;
        case SWD_TO_DORMANT:
                LOG_DEBUG("SWD-to-DORMANT");
                s = swd_seq_swd_to_dormant;
                s_len = swd_seq_swd_to_dormant_len;
                break;
        case DORMANT_TO_SWD:
                LOG_DEBUG("DORMANT-to-SWD");
                s = swd_seq_dormant_to_swd;
                s_len = swd_seq_dormant_to_swd_len;
                break;
        case DORMANT_TO_JTAG:
                LOG_DEBUG("DORMANT-to-JTAG");
                s = swd_seq_dormant_to_jtag;
                s_len = swd_seq_dormant_to_jtag_len;
                break;
        default:
                LOG_ERROR("Sequence %d not supported", seq);
                return ERROR_FAIL;
        }

        retval = cmsis_dap_cmd_dap_swj_sequence(s_len, s);
        if (retval != ERROR_OK)
                return retval;

        /* Atmel EDBG needs renew clock setting after SWJ_Sequence
         * otherwise default frequency is used */
        return cmsis_dap_cmd_dap_swj_clock(adapter_get_speed_khz());
}

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

        int 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)
{
        uint8_t *data;

        int retval = cmsis_dap_open();
        if (retval != ERROR_OK)
                return retval;

        cmsis_dap_flush_read(cmsis_dap_handle);

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

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

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

        if (swd_mode) {
                retval = cmsis_dap_swd_open();
                if (retval != ERROR_OK)
                        return retval;
        } else {
                /* 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)");
        }

        /* Be conservative and suppress submitting multiple HID requests
         * until we get packet count info from the adaptor */
        cmsis_dap_handle->packet_count = 1;
        pending_queue_len = 12;

        /* INFO_ID_PKT_SZ - short */
        retval = cmsis_dap_cmd_dap_info(INFO_ID_PKT_SZ, &data);
        if (retval != ERROR_OK)
                goto init_err;

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

                        /* 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;

                        free(cmsis_dap_handle->packet_buffer);
                        retval = cmsis_dap_handle->backend->packet_buffer_alloc(cmsis_dap_handle, pkt_sz);
                        if (retval != ERROR_OK)
                                goto init_err;

                        LOG_DEBUG("CMSIS-DAP: Packet Size = %" PRIu16, pkt_sz);
                }
        }

        /* INFO_ID_PKT_CNT - byte */
        retval = cmsis_dap_cmd_dap_info(INFO_ID_PKT_CNT, &data);
        if (retval != ERROR_OK)
                goto init_err;

        if (data[0] == 1) { /* byte */
                int pkt_cnt = data[1];
                if (pkt_cnt > 1)
                        cmsis_dap_handle->packet_count = MIN(MAX_PENDING_REQUESTS, pkt_cnt);

                LOG_DEBUG("CMSIS-DAP: Packet Count = %d", pkt_cnt);
        }

        LOG_DEBUG("Allocating FIFO for %d pending packets", cmsis_dap_handle->packet_count);
        for (int i = 0; i < cmsis_dap_handle->packet_count; i++) {
                pending_fifo[i].transfers = malloc(pending_queue_len * sizeof(struct pending_transfer_result));
                if (!pending_fifo[i].transfers) {
                        LOG_ERROR("Unable to allocate memory for CMSIS-DAP queue");
                        retval = ERROR_FAIL;
                        goto init_err;
                }
        }

        /* Intentionally not checked for error, just logs an info message
         * not vital for further debugging */
        (void)cmsis_dap_get_status();

        /* Now try to connect to the target
         * TODO: This is all SWD only @ present */
        retval = cmsis_dap_cmd_dap_swj_clock(adapter_get_speed_khz());
        if (retval != ERROR_OK)
                goto init_err;

        /* 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)
                goto init_err;

        if (swd_mode) {
                /* 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)
                        goto init_err;
        }
        /* Both LEDs on */
        /* Intentionally not checked for error, debugging will work
         * without LEDs */
        (void)cmsis_dap_cmd_dap_led(LED_ID_CONNECT, LED_ON);
        (void)cmsis_dap_cmd_dap_led(LED_ID_RUN, LED_ON);

        /* 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, SWJ_PIN_SRST, 0, NULL);
                        if (retval != ERROR_OK)
                                goto init_err;
                        LOG_INFO("Connecting under reset");
                }
        }
        LOG_INFO("CMSIS-DAP: Interface ready");
        return ERROR_OK;

init_err:
        cmsis_dap_quit();
        return retval;
}

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

static int cmsis_dap_quit(void)
{
        cmsis_dap_cmd_dap_disconnect();

        /* Both LEDs off */
        cmsis_dap_cmd_dap_led(LED_ID_RUN, LED_OFF);
        cmsis_dap_cmd_dap_led(LED_ID_CONNECT, LED_OFF);

        cmsis_dap_close(cmsis_dap_handle);

        return ERROR_OK;
}

static int cmsis_dap_reset(int trst, int srst)
{
        /* Set both TRST and SRST even if they're not enabled as
         * there's no way to tristate them */

        output_pins = 0;
        if (!srst)
                output_pins |= SWJ_PIN_SRST;
        if (!trst)
                output_pins |= SWJ_PIN_TRST;

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

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 retval = cmsis_dap_cmd_dap_swj_sequence(8, &seq);
        if (retval == ERROR_OK)
                tap_set_state(TAP_RESET);
        return retval;
}

/* 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[0]) {
                case CMD_DAP_JTAG_SEQ: {
                        printf("cmsis-dap jtag sequence command %02x (n=%d)\n", cmd[0], cmd[1]);
                        /*
                         * #1 = number of sequences
                         * #2 = sequence info 1
                         * #3...4+n_bytes-1 = sequence 1
                         * #4+n_bytes = sequence info 2
                         * #5+n_bytes = sequence 2 (single bit)
                         */
                        int pos = 2;
                        for (int seq = 0; seq < cmd[1]; ++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;

        LOG_DEBUG_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);

        /* prepare CMSIS-DAP packet */
        uint8_t *command = cmsis_dap_handle->command;
        command[0] = CMD_DAP_JTAG_SEQ;
        command[1] = queued_seq_count;
        memcpy(&command[2], queued_seq_buf, queued_seq_buf_end);

#ifdef CMSIS_DAP_JTAG_DEBUG
        debug_parse_cmsis_buf(command, queued_seq_buf_end + 2);
#endif

        /* send command to USB device */
        int retval = cmsis_dap_xfer(cmsis_dap_handle, queued_seq_buf_end + 2);

        uint8_t *resp = cmsis_dap_handle->response;
        if (retval != ERROR_OK || resp[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DAP_JTAG_SEQ failed.");
                exit(-1);
        }

#ifdef CMSIS_DAP_JTAG_DEBUG
        LOG_DEBUG_IO("USB response buf:");
        for (int c = 0; c < queued_seq_buf_end + 3; ++c)
                printf("%02X ", resp[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];
                LOG_DEBUG_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 ", resp[2+scan->first+b]);
                printf("\n");
#endif
                bit_copy(scan->buffer, scan->buffer_offset, &resp[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)
{
        LOG_DEBUG_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) {
                LOG_DEBUG_IO("START JTAG SEQ SPLIT");
                for (int offset = 0; offset < s_len; offset += 64) {
                        int len = s_len - offset;
                        if (len > 64)
                                len = 64;
                        LOG_DEBUG_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 ? 0 : (tdo_buffer_offset + offset)
                                );
                }
                LOG_DEBUG_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 ? DAP_JTAG_SEQ_TDO : 0) |
                (s_len == 64 ? 0 : s_len);

        if (sequence)
                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) {
                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)
{
        LOG_DEBUG_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 = 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());

        LOG_DEBUG_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)
{
        LOG_DEBUG_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;
                LOG_DEBUG_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()) {
                        LOG_DEBUG_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 {
                        LOG_DEBUG_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();
        }

        LOG_DEBUG_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)
{
        uint8_t tms0 = 0x00;
        uint8_t tms1 = 0xff;

        for (int 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)
{
        LOG_DEBUG_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)
{
        uint8_t tms = tap_get_state() == TAP_RESET;
        /* TODO: Perform optimizations? */
        /* Execute num_cycles. */
        for (int 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)
{
        LOG_DEBUG_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)
{
        LOG_DEBUG_IO("stableclocks %i cycles", cmd->cmd.runtest->num_cycles);
        cmsis_dap_stableclocks(cmd->cmd.runtest->num_cycles);
}

static void cmsis_dap_execute_tms(struct jtag_command *cmd)
{
        LOG_DEBUG_IO("TMS: %d bits", cmd->cmd.tms->num_bits);
        cmsis_dap_cmd_dap_swj_sequence(cmd->cmd.tms->num_bits, cmd->cmd.tms->bits);
}

/* 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_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:
                        cmsis_dap_execute_tms(cmd);
                        break;
                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) {
                cmsis_dap_execute_command(cmd);
                cmd = cmd->next;
        }

        cmsis_dap_flush();

        return ERROR_OK;
}

static int cmsis_dap_speed(int speed)
{
        if (speed == 0) {
                LOG_ERROR("RTCK not supported. Set nonzero \"adapter speed\".");
                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 bool calculate_swo_prescaler(unsigned int traceclkin_freq,
                uint32_t trace_freq, uint16_t *prescaler)
{
        unsigned int presc = (traceclkin_freq + trace_freq / 2) / trace_freq;
        if (presc == 0 || presc > TPIU_ACPR_MAX_SWOSCALER + 1)
                return false;

        /* Probe's UART speed must be within 3% of the TPIU's SWO baud rate. */
        unsigned int max_deviation = (traceclkin_freq * 3) / 100;
        if (presc * trace_freq < traceclkin_freq - max_deviation ||
            presc * trace_freq > traceclkin_freq + max_deviation)
                return false;

        *prescaler = presc;

        return true;
}

/**
 * @see adapter_driver::config_trace
 */
static int cmsis_dap_config_trace(
                                bool trace_enabled,
                                enum tpiu_pin_protocol pin_protocol,
                                uint32_t port_size,
                                unsigned int *swo_freq,
                                unsigned int traceclkin_hz,
                                uint16_t *swo_prescaler)
{
        int retval;

        if (!trace_enabled) {
                if (cmsis_dap_handle->trace_enabled) {
                        retval = cmsis_dap_cmd_dap_swo_control(DAP_SWO_CONTROL_STOP);
                        if (retval != ERROR_OK) {
                                LOG_ERROR("Failed to disable the SWO-trace.");
                                return retval;
                        }
                }
                cmsis_dap_handle->trace_enabled = false;
                LOG_INFO("SWO-trace disabled.");
                return ERROR_OK;
        }

        if (!(cmsis_dap_handle->caps & INFO_CAPS_SWO_UART) &&
            !(cmsis_dap_handle->caps & INFO_CAPS_SWO_MANCHESTER)) {
                LOG_ERROR("SWO-trace is not supported by the device.");
                return ERROR_FAIL;
        }

        uint8_t swo_mode;
        if (pin_protocol == TPIU_PIN_PROTOCOL_ASYNC_UART &&
           (cmsis_dap_handle->caps & INFO_CAPS_SWO_UART)) {
                swo_mode = DAP_SWO_MODE_UART;
        } else if (pin_protocol == TPIU_PIN_PROTOCOL_ASYNC_MANCHESTER &&
                  (cmsis_dap_handle->caps & INFO_CAPS_SWO_MANCHESTER)) {
                swo_mode = DAP_SWO_MODE_MANCHESTER;
        } else {
                LOG_ERROR("Selected pin protocol is not supported.");
                return ERROR_FAIL;
        }

        if (*swo_freq == 0) {
                LOG_INFO("SWO-trace frequency autodetection not implemented.");
                return ERROR_FAIL;
        }

        retval = cmsis_dap_cmd_dap_swo_control(DAP_SWO_CONTROL_STOP);
        if (retval != ERROR_OK)
                return retval;

        cmsis_dap_handle->trace_enabled = false;

        retval = cmsis_dap_get_swo_buf_sz(&cmsis_dap_handle->swo_buf_sz);
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_cmd_dap_swo_transport(DAP_SWO_TRANSPORT_DATA);
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_cmd_dap_swo_mode(swo_mode);
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_cmd_dap_swo_baudrate(*swo_freq, swo_freq);
        if (retval != ERROR_OK)
                return retval;

        if (!calculate_swo_prescaler(traceclkin_hz, *swo_freq,
                        swo_prescaler)) {
                LOG_ERROR("SWO frequency is not suitable. Please choose a "
                        "different frequency or use auto-detection.");
                return ERROR_FAIL;
        }

        LOG_INFO("SWO frequency: %u Hz.", *swo_freq);
        LOG_INFO("SWO prescaler: %u.", *swo_prescaler);

        retval = cmsis_dap_cmd_dap_swo_control(DAP_SWO_CONTROL_START);
        if (retval != ERROR_OK)
                return retval;

        cmsis_dap_handle->trace_enabled = true;

        return ERROR_OK;
}

/**
 * @see adapter_driver::poll_trace
 */
static int cmsis_dap_poll_trace(uint8_t *buf, size_t *size)
{
        uint8_t trace_status;
        size_t trace_count;

        if (!cmsis_dap_handle->trace_enabled) {
                *size = 0;
                return ERROR_OK;
        }

        int retval = cmsis_dap_cmd_dap_swo_status(&trace_status, &trace_count);
        if (retval != ERROR_OK)
                return retval;
        if ((trace_status & DAP_SWO_STATUS_CAPTURE_MASK) != DAP_SWO_STATUS_CAPTURE_ACTIVE)
                return ERROR_FAIL;

        *size = trace_count < *size ? trace_count : *size;
        size_t read_so_far = 0;
        do {
                size_t rb = 0;
                uint32_t packet_size = cmsis_dap_handle->packet_size - 4 /*data-reply*/;
                uint32_t remaining = *size - read_so_far;
                if (remaining < packet_size)
                        packet_size = remaining;
                retval = cmsis_dap_cmd_dap_swo_data(
                                                packet_size,
                                                &trace_status,
                                                &rb,
                                                &buf[read_so_far]);
                if (retval != ERROR_OK)
                        return retval;
                if ((trace_status & DAP_SWO_STATUS_CAPTURE_MASK) != DAP_SWO_STATUS_CAPTURE_ACTIVE)
                        return ERROR_FAIL;

                read_so_far += rb;
        } while (read_so_far < *size);

        return ERROR_OK;
}

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_cmd_command)
{
        uint8_t *command = cmsis_dap_handle->command;

        for (unsigned i = 0; i < CMD_ARGC; i++)
                COMMAND_PARSE_NUMBER(u8, CMD_ARGV[i], command[i]);

        int retval = cmsis_dap_xfer(cmsis_dap_handle, CMD_ARGC);

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

        uint8_t *resp = cmsis_dap_handle->response;
        LOG_INFO("Returned data %02" PRIx8 " %02" PRIx8 " %02" PRIx8 " %02" PRIx8,
                resp[1], resp[2], resp[3], resp[4]);

        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_backend_command)
{
        if (CMD_ARGC == 1) {
                if (strcmp(CMD_ARGV[0], "auto") == 0) {
                        cmsis_dap_backend = -1; /* autoselect */
                } else {
                        for (unsigned int i = 0; i < ARRAY_SIZE(cmsis_dap_backends); i++) {
                                if (strcasecmp(cmsis_dap_backends[i]->name, CMD_ARGV[0]) == 0) {
                                        cmsis_dap_backend = i;
                                        return ERROR_OK;
                                }
                        }

                        LOG_ERROR("invalid backend argument to cmsis_dap_backend <backend>");
                }
        } else {
                LOG_ERROR("expected exactly one argument to cmsis_dap_backend <backend>");
        }

        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",
        },
        {
                .name = "cmd",
                .handler = &cmsis_dap_handle_cmd_command,
                .mode = COMMAND_EXEC,
                .usage = "",
                .help = "issue cmsis-dap command",
        },
        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_backend",
                .handler = &cmsis_dap_handle_backend_command,
                .mode = COMMAND_CONFIG,
                .help = "set the communication backend to use (USB bulk or HID).",
                .usage = "(auto | usb_bulk | hid)",
        },
#if BUILD_CMSIS_DAP_USB
        {
                .name = "cmsis_dap_usb",
                .chain = cmsis_dap_usb_subcommand_handlers,
                .mode = COMMAND_ANY,
                .help = "USB bulk backend-specific commands",
                .usage = "<cmd>",
        },
#endif
        COMMAND_REGISTRATION_DONE
};

static const struct swd_driver cmsis_dap_swd_driver = {
        .init = cmsis_dap_swd_init,
        .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 };

static struct jtag_interface cmsis_dap_interface = {
        .supported = DEBUG_CAP_TMS_SEQ,
        .execute_queue = cmsis_dap_execute_queue,
};

struct adapter_driver cmsis_dap_adapter_driver = {
        .name = "cmsis-dap",
        .transports = cmsis_dap_transport,
        .commands = cmsis_dap_command_handlers,

        .init = cmsis_dap_init,
        .quit = cmsis_dap_quit,
        .reset = cmsis_dap_reset,
        .speed = cmsis_dap_speed,
        .khz = cmsis_dap_khz,
        .speed_div = cmsis_dap_speed_div,
        .config_trace = cmsis_dap_config_trace,
        .poll_trace = cmsis_dap_poll_trace,

        .jtag_ops = &cmsis_dap_interface,
        .swd_ops = &cmsis_dap_swd_driver,
};