dirtyjtag_spi.c - flashprog - Gitiles

 /*
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2021-2022 Jean THOMAS <virgule@jeanthomas.me>
  *
  * 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.
  */

 /*
  * Driver for the DirtyJTAG project.
  * See https://github.com/jeanthom/dirtyjtag for more info.
  *
  *  SPI-JTAG Pin Mapping
  * |=========|==========|
  * | SPI pin | JTAG pin |
  * |=========|==========|
  * | #CS     | TMS      |
  * | #WP     | SRST     |
  * | #HOLD   | TRST     |
  * | MISO    | TDO      |
  * | MOSI    | TDI      |
  * | CLK     | TCK      |
  * |=========|==========|
  */

 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <libusb.h>
 #include "programmer.h"

 struct dirtyjtag_spi_data {
 	struct libusb_context *libusb_ctx;
 	struct libusb_device_handle *libusb_handle;
 };

 static const struct dev_entry devs_dirtyjtag_spi[] = {
 	{ 0x1209, 0xc0ca, OK, "DirtyJTAG", "JTAG probe" },
 	{ 0 },
 };

 static const char dirtyjtag_write_endpoint = 0x01;
 static const char dirtyjtag_read_endpoint = 0x82;
 static const int dirtyjtag_timeout = 100 * 10; /* 100 ms */

 enum dirtyjtag_command_identifier {
 	CMD_STOP = 0x00,
 	CMD_INFO = 0x01,
 	CMD_FREQ = 0x02,
 	CMD_XFER = 0x03,
 	CMD_SETSIG = 0x04,
 	CMD_GETSIG = 0x05,
 	CMD_CLK = 0x06
 };

 enum dirtyjtag_command_modifier {
 	/* CMD_XFER */
 	NO_READ		= 0x80,
 	EXTEND_LENGTH	= 0x40,
 	/* CMD_CLK */
 	READOUT		= 0x80,
 };

 enum dirtyjtag_signal_identifier {
 	SIG_TCK = 1 << 1,
 	SIG_TDI = 1 << 2,
 	SIG_TDO = 1 << 3,
 	SIG_TMS = 1 << 4,
 	SIG_TRST = 1 << 5,
 	SIG_SRST = 1 << 6
 };

 static int dirtyjtag_send(struct dirtyjtag_spi_data *djtag_data, uint8_t *data, size_t len)
 {
 	int transferred;
 	int ret = libusb_bulk_transfer(djtag_data->libusb_handle,
 		dirtyjtag_write_endpoint,
 		data,
 		len,
 		&transferred,
 		dirtyjtag_timeout);
 	if (ret != 0) {
 		msg_perr("%s: failed to send query command\n", __func__);
 		return -1;
 	}
 	if (transferred != (int)len) {
 		msg_perr("%s: failed to send whole packet\n", __func__);
 		return -1;
 	}

 	return 0;
 }

 static int dirtyjtag_receive(struct dirtyjtag_spi_data *djtag_data, uint8_t *data, size_t buffer_len, int expected)
 {
 	int transferred;
 	int ret = libusb_bulk_transfer(djtag_data->libusb_handle,
 		dirtyjtag_read_endpoint,
 		data,
 		buffer_len,
 		&transferred,
 		dirtyjtag_timeout);
 	if (ret != 0) {
 		msg_perr("%s: Failed to read SPI commands\n", __func__);
 		return -1;
 	}

 	if (expected != -1 && transferred != expected) {
 		msg_perr("%s: failed to meet expected\n", __func__);
 		return -1;
 	}

 	return transferred;
 }

 static char *dirtyjtag_info(struct dirtyjtag_spi_data *djtag_data)
 {
 	uint8_t buffer[64] = {
 		CMD_INFO,
 	};

 	if (dirtyjtag_send(djtag_data, buffer, 1))
 		return NULL;

 	const int transferred = dirtyjtag_receive(djtag_data, buffer, sizeof(buffer), -1);
 	if (transferred < 1)
 		return NULL;

 	return strndup((char *)buffer, transferred);
 }

 static unsigned int dirtyjtag_version(const char *info)
 {
 	if (!strncmp(info, "DJTAG1\n", 7))
 		return 1;
 	if (!strncmp(info, "DJTAG2\n", 7))
 		return 2;
 	return 0;
 }

 static int dirtyjtag_spi_shutdown(void *data)
 {
 	struct dirtyjtag_spi_data *djtag_data = (struct dirtyjtag_spi_data*)data;
 	libusb_release_interface(djtag_data->libusb_handle, 0);
 	libusb_attach_kernel_driver(djtag_data->libusb_handle, 0);
 	libusb_close(djtag_data->libusb_handle);
 	libusb_exit(djtag_data->libusb_ctx);
 	free(data);
 	return 0;
 }

 static int dirtyjtag_reset_tms(struct dirtyjtag_spi_data *context)
 {
 	uint8_t tms_reset_buffer[] = {
 		CMD_SETSIG,
 		SIG_TMS,
 		SIG_TMS,

 		CMD_STOP,
 	};
 	return dirtyjtag_send(context, tms_reset_buffer, sizeof(tms_reset_buffer));
 }

 static int dirtyjtag_djtag1_spi_send_command(const struct flashctx *flash,
 					     unsigned int writecnt, unsigned int readcnt,
 					     const unsigned char *writearr, unsigned char *readarr)
 {
 	struct dirtyjtag_spi_data *context = flash->mst.spi->data;
 	const size_t max_xfer_size = 30; // max transfer size in DJTAG1
 	size_t len = writecnt + readcnt;
 	size_t num_xfer = (len + max_xfer_size - 1 ) / max_xfer_size; // ceil(len/max_xfer_size)
 	size_t i;

 	uint8_t *rxtx_buffer = malloc(max_xfer_size * num_xfer);
 	if (!rxtx_buffer) {
 		msg_perr("%s: Failed rxtx_buffer allocation\n", __func__);
 		return -1;
 	}

 	memcpy(rxtx_buffer, writearr, writecnt);
 	for (i = 0; i < num_xfer; i++) {
 		const size_t xfer_offset = i * max_xfer_size;
 		size_t txn_size = max_xfer_size;
 		if (i == num_xfer-1 && len % max_xfer_size != 0)
 			txn_size = len % max_xfer_size;

 		uint8_t transfer_buffer[32] = {
 			CMD_XFER,
 			txn_size * 8
 		};
 		memcpy(transfer_buffer + 2, rxtx_buffer + xfer_offset, txn_size);

 		if (dirtyjtag_send(context, transfer_buffer, sizeof(transfer_buffer)))
 			goto cleanup_fail;

 		if (dirtyjtag_receive(context, transfer_buffer, sizeof(transfer_buffer), 32) < 0)
 			goto cleanup_fail;

 		memcpy(rxtx_buffer + xfer_offset, transfer_buffer, txn_size);
 	}
 	memcpy(readarr, rxtx_buffer + writecnt, readcnt);

 	free(rxtx_buffer);

 	dirtyjtag_reset_tms(context);

 	return 0;

 cleanup_fail:
 	free(rxtx_buffer);
 	return -1;
 }

 static int dirtyjtag_djtag2_spi_send_command(const struct flashctx *flash,
 					     unsigned int writecnt, unsigned int readcnt,
 					     const unsigned char *writearr, unsigned char *readarr)
 {
 	struct dirtyjtag_spi_data *const context = flash->mst.spi->data;
 	const size_t max_xfer_size = 62; /* max transfer size in DJTAG2 */
 	uint8_t transfer_buffer[2 + max_xfer_size]; /* 1B command + 1B len + payload */
 	size_t i;

 	i = 0;
 	while (i < writecnt) {
 		const size_t txn_size = MIN(max_xfer_size, writecnt - i);

 		transfer_buffer[0] = CMD_XFER | NO_READ;
 		if (txn_size * 8 >= 256)
 			transfer_buffer[0] |= EXTEND_LENGTH;
 		transfer_buffer[1] = (txn_size * 8) % 256;
 		memcpy(transfer_buffer + 2, writearr + i, txn_size);

 		if (dirtyjtag_send(context, transfer_buffer, 2 + txn_size))
 			return -1;

 		i += txn_size;
 	}

 	i = 0;
 	while (i < readcnt) {
 		const size_t rxn_size = MIN(max_xfer_size, readcnt - i);

 		transfer_buffer[0] = CMD_XFER;
 		if (rxn_size * 8 >= 256)
 			transfer_buffer[0] |= EXTEND_LENGTH;
 		transfer_buffer[1] = (rxn_size * 8) % 256;

 		if (dirtyjtag_send(context, transfer_buffer, 2 + rxn_size))
 			return -1;

 		if (dirtyjtag_receive(context, readarr + i, rxn_size, rxn_size) < 0)
 			return -1;

 		i += rxn_size;
 	}

 	dirtyjtag_reset_tms(context);

 	return 0;
 }

 static const struct spi_master spi_master_dirtyjtag_spi = {
 	.features	= SPI_MASTER_4BA,
 	.max_data_read	= MAX_DATA_READ_UNLIMITED,
 	.max_data_write	= MAX_DATA_WRITE_UNLIMITED,
 	.multicommand	= default_spi_send_multicommand,
 	.read		= default_spi_read,
 	.write_256	= default_spi_write_256,
 	.shutdown	= dirtyjtag_spi_shutdown,
 	.probe_opcode	= default_spi_probe_opcode,
 };

 static int dirtyjtag_spi_init(struct flashprog_programmer *const prog)
 {
 	struct spi_master dirtyjtag_spi = spi_master_dirtyjtag_spi;
 	struct libusb_device_handle *handle = NULL;
 	struct dirtyjtag_spi_data *djtag_data = NULL;

 	djtag_data = calloc(1, sizeof(struct dirtyjtag_spi_data));
 	if (djtag_data == NULL) {
 		msg_perr("%s: failed to allocate internal driver data structure\n", __func__);
 		return -1;
 	}

 	int ret = libusb_init(&djtag_data->libusb_ctx);
 	if (ret < 0) {
 		msg_perr("%s: couldn't initialize libusb!\n", __func__);
 		goto cleanup_djtag_struct;
 	}

 #if LIBUSB_API_VERSION < 0x01000106
 	libusb_set_debug(djtag_data->libusb_ctx, 3);
 #else
 	libusb_set_option(djtag_data->libusb_ctx, LIBUSB_OPTION_LOG_LEVEL, LIBUSB_LOG_LEVEL_INFO);
 #endif

 	uint16_t vid = devs_dirtyjtag_spi[0].vendor_id;
 	uint16_t pid = devs_dirtyjtag_spi[0].device_id;
 	handle = libusb_open_device_with_vid_pid(djtag_data->libusb_ctx, vid, pid);
 	if (handle == NULL) {
 		msg_perr("%s: couldn't open device %04x:%04x.\n", __func__, vid, pid);
 		goto cleanup_libusb_ctx;
 	}

 	ret = libusb_detach_kernel_driver(handle, 0);
 	if (ret != 0 && ret != LIBUSB_ERROR_NOT_FOUND) {
 		msg_pwarn("Cannot detach the existing USB driver. Claiming the interface may fail. %s\n",
 			libusb_error_name(ret));
 	}

 	ret = libusb_claim_interface(handle, 0);
 	if (ret != 0) {
 		msg_perr("%s: failed to claim interface 0: '%s'\n", __func__, libusb_error_name(ret));
 		goto cleanup_libusb_handle;
 	}

 	djtag_data->libusb_handle = handle;

 	unsigned long int freq = 100;
 	char *tmp = extract_programmer_param("spispeed");
 	if (tmp) {
 		char *units = tmp;

 		errno = 0;
 		freq = strtoul(tmp, &units, 0);
 		if (errno) {
 			msg_perr("Invalid frequency \"%s\", %s\n", tmp, strerror(errno));
 			free(tmp);
 			goto cleanup_libusb_handle;
 		}

 		if (!strcasecmp(units, "hz")) {
 			freq /= 1000;
 		} else if (!strcasecmp(units, "khz")) {
 			/* Do nothing, already in the right unit */
 		} else if (!strcasecmp(units, "mhz")) {
 			freq *= 1000;
 		} else {
 			msg_perr("Invalid unit: %s, use hz, khz or mhz\n", units);
 			free(tmp);
 			goto cleanup_libusb_handle;
 		}

 		if (freq > UINT16_MAX) {
 			msg_perr("%s: Frequency set above DJTAG1/2 limits (%d kHz)\n", __func__, UINT16_MAX);
 			free(tmp);
 			goto cleanup_libusb_handle;
 		}

 		msg_pinfo("%s: programmer speed set to %lu kHz\n", __func__, freq);
 	}
 	free(tmp);

 	char *const info = dirtyjtag_info(djtag_data);
 	if (!info) {
 		msg_perr("Failed to read DirtyJTAG Info.\n");
 		goto cleanup_libusb_handle;
 	}

 	msg_pinfo("DirtyJTAG Info: %s\n", info);
 	const unsigned int djtag_version = dirtyjtag_version(info);
 	switch (djtag_version) {
 	default:
 		msg_pwarn("Warning: Unknown DJTAG version %u. Assuming DJTAG2 compatibility.\n",
 			  djtag_version);
 		/* fall-through */
 	case 2:
 		dirtyjtag_spi.command = dirtyjtag_djtag2_spi_send_command;
 		break;
 	case 1:
 		dirtyjtag_spi.command = dirtyjtag_djtag1_spi_send_command;
 		break;
 	}
 	free(info);

 	uint8_t commands[] = {
 		CMD_SETSIG, /* Set TDI/TCK to low, SRST/TRST/TMS to high */
 		SIG_TDI | SIG_TMS | SIG_TCK | SIG_SRST | SIG_TRST,
 		SIG_SRST | SIG_TRST | SIG_TMS,

 		CMD_FREQ, /* Set frequency */
 		(freq >> 8) & 0xff,
 		freq & 0xff,

 		CMD_STOP,
 	};
 	ret = dirtyjtag_send(djtag_data, commands, sizeof(commands));
 	if (ret != 0) {
 		msg_perr("%s: failed to configure DirtyJTAG into initialized state\n", __func__);
 		goto cleanup_libusb_handle;
 	}

 	return register_spi_master(&dirtyjtag_spi, 0, djtag_data);

 cleanup_libusb_handle:
 	libusb_attach_kernel_driver(handle, 0);
 	libusb_close(handle);

 cleanup_libusb_ctx:
 	libusb_exit(djtag_data->libusb_ctx);

 cleanup_djtag_struct:
 	free(djtag_data);
 	return -1;
 }

 const struct programmer_entry programmer_dirtyjtag_spi = {
 	.name			= "dirtyjtag_spi",
 	.type			= USB,
 	.devs.dev		= devs_dirtyjtag_spi,
 	.init			= dirtyjtag_spi_init,
 };
	/*
	* This file is part of the flashrom project.
	*
	* Copyright (C) 2021-2022 Jean THOMAS <virgule@jeanthomas.me>
	*
	* 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.
	*/

	/*
	* Driver for the DirtyJTAG project.
	* See https://github.com/jeanthom/dirtyjtag for more info.
	*
	* SPI-JTAG Pin Mapping
	* \|=========\|==========\|
	* \| SPI pin \| JTAG pin \|
	* \|=========\|==========\|
	* \| #CS \| TMS \|
	* \| #WP \| SRST \|
	* \| #HOLD \| TRST \|
	* \| MISO \| TDO \|
	* \| MOSI \| TDI \|
	* \| CLK \| TCK \|
	* \|=========\|==========\|
	*/

	#include <assert.h>
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <libusb.h>
	#include "programmer.h"

	struct dirtyjtag_spi_data {
	struct libusb_context *libusb_ctx;
	struct libusb_device_handle *libusb_handle;
	};

	static const struct dev_entry devs_dirtyjtag_spi[] = {
	{ 0x1209, 0xc0ca, OK, "DirtyJTAG", "JTAG probe" },
	{ 0 },
	};

	static const char dirtyjtag_write_endpoint = 0x01;
	static const char dirtyjtag_read_endpoint = 0x82;
	static const int dirtyjtag_timeout = 100 * 10; /* 100 ms */

	enum dirtyjtag_command_identifier {
	CMD_STOP = 0x00,
	CMD_INFO = 0x01,
	CMD_FREQ = 0x02,
	CMD_XFER = 0x03,
	CMD_SETSIG = 0x04,
	CMD_GETSIG = 0x05,
	CMD_CLK = 0x06
	};

	enum dirtyjtag_command_modifier {
	/* CMD_XFER */
	NO_READ = 0x80,
	EXTEND_LENGTH = 0x40,
	/* CMD_CLK */
	READOUT = 0x80,
	};

	enum dirtyjtag_signal_identifier {
	SIG_TCK = 1 << 1,
	SIG_TDI = 1 << 2,
	SIG_TDO = 1 << 3,
	SIG_TMS = 1 << 4,
	SIG_TRST = 1 << 5,
	SIG_SRST = 1 << 6
	};

	static int dirtyjtag_send(struct dirtyjtag_spi_data djtag_data, uint8_t data, size_t len)
	{
	int transferred;
	int ret = libusb_bulk_transfer(djtag_data->libusb_handle,
	dirtyjtag_write_endpoint,
	data,
	len,
	&transferred,
	dirtyjtag_timeout);
	if (ret != 0) {
	msg_perr("%s: failed to send query command\n", __func__);
	return -1;
	}
	if (transferred != (int)len) {
	msg_perr("%s: failed to send whole packet\n", __func__);
	return -1;
	}

	return 0;
	}

	static int dirtyjtag_receive(struct dirtyjtag_spi_data djtag_data, uint8_t data, size_t buffer_len, int expected)
	{
	int transferred;
	int ret = libusb_bulk_transfer(djtag_data->libusb_handle,
	dirtyjtag_read_endpoint,
	data,
	buffer_len,
	&transferred,
	dirtyjtag_timeout);
	if (ret != 0) {
	msg_perr("%s: Failed to read SPI commands\n", __func__);
	return -1;
	}

	if (expected != -1 && transferred != expected) {
	msg_perr("%s: failed to meet expected\n", __func__);
	return -1;
	}

	return transferred;
	}

	static char dirtyjtag_info(struct dirtyjtag_spi_data djtag_data)
	{
	uint8_t buffer[64] = {
	CMD_INFO,
	};

	if (dirtyjtag_send(djtag_data, buffer, 1))
	return NULL;

	const int transferred = dirtyjtag_receive(djtag_data, buffer, sizeof(buffer), -1);
	if (transferred < 1)
	return NULL;

	return strndup((char *)buffer, transferred);
	}

	static unsigned int dirtyjtag_version(const char *info)
	{
	if (!strncmp(info, "DJTAG1\n", 7))
	return 1;
	if (!strncmp(info, "DJTAG2\n", 7))
	return 2;
	return 0;
	}

	static int dirtyjtag_spi_shutdown(void *data)
	{
	struct dirtyjtag_spi_data djtag_data = (struct dirtyjtag_spi_data)data;
	libusb_release_interface(djtag_data->libusb_handle, 0);
	libusb_attach_kernel_driver(djtag_data->libusb_handle, 0);
	libusb_close(djtag_data->libusb_handle);
	libusb_exit(djtag_data->libusb_ctx);
	free(data);
	return 0;
	}

	static int dirtyjtag_reset_tms(struct dirtyjtag_spi_data *context)
	{
	uint8_t tms_reset_buffer[] = {
	CMD_SETSIG,
	SIG_TMS,
	SIG_TMS,

	CMD_STOP,
	};
	return dirtyjtag_send(context, tms_reset_buffer, sizeof(tms_reset_buffer));
	}

	static int dirtyjtag_djtag1_spi_send_command(const struct flashctx *flash,
	unsigned int writecnt, unsigned int readcnt,
	const unsigned char writearr, unsigned char readarr)
	{
	struct dirtyjtag_spi_data *context = flash->mst.spi->data;
	const size_t max_xfer_size = 30; // max transfer size in DJTAG1
	size_t len = writecnt + readcnt;
	size_t num_xfer = (len + max_xfer_size - 1 ) / max_xfer_size; // ceil(len/max_xfer_size)
	size_t i;

	uint8_t rxtx_buffer = malloc(max_xfer_size num_xfer);
	if (!rxtx_buffer) {
	msg_perr("%s: Failed rxtx_buffer allocation\n", __func__);
	return -1;
	}

	memcpy(rxtx_buffer, writearr, writecnt);
	for (i = 0; i < num_xfer; i++) {
	const size_t xfer_offset = i * max_xfer_size;
	size_t txn_size = max_xfer_size;
	if (i == num_xfer-1 && len % max_xfer_size != 0)
	txn_size = len % max_xfer_size;

	uint8_t transfer_buffer[32] = {
	CMD_XFER,
	txn_size * 8
	};
	memcpy(transfer_buffer + 2, rxtx_buffer + xfer_offset, txn_size);

	if (dirtyjtag_send(context, transfer_buffer, sizeof(transfer_buffer)))
	goto cleanup_fail;

	if (dirtyjtag_receive(context, transfer_buffer, sizeof(transfer_buffer), 32) < 0)
	goto cleanup_fail;

	memcpy(rxtx_buffer + xfer_offset, transfer_buffer, txn_size);
	}
	memcpy(readarr, rxtx_buffer + writecnt, readcnt);

	free(rxtx_buffer);

	dirtyjtag_reset_tms(context);

	return 0;

	cleanup_fail:
	free(rxtx_buffer);
	return -1;
	}

	static int dirtyjtag_djtag2_spi_send_command(const struct flashctx *flash,
	unsigned int writecnt, unsigned int readcnt,
	const unsigned char writearr, unsigned char readarr)
	{
	struct dirtyjtag_spi_data *const context = flash->mst.spi->data;
	const size_t max_xfer_size = 62; /* max transfer size in DJTAG2 */
	uint8_t transfer_buffer[2 + max_xfer_size]; /* 1B command + 1B len + payload */
	size_t i;

	i = 0;
	while (i < writecnt) {
	const size_t txn_size = MIN(max_xfer_size, writecnt - i);

	transfer_buffer[0] = CMD_XFER \| NO_READ;
	if (txn_size * 8 >= 256)
	transfer_buffer[0] \|= EXTEND_LENGTH;
	transfer_buffer[1] = (txn_size * 8) % 256;
	memcpy(transfer_buffer + 2, writearr + i, txn_size);

	if (dirtyjtag_send(context, transfer_buffer, 2 + txn_size))
	return -1;

	i += txn_size;
	}

	i = 0;
	while (i < readcnt) {
	const size_t rxn_size = MIN(max_xfer_size, readcnt - i);

	transfer_buffer[0] = CMD_XFER;
	if (rxn_size * 8 >= 256)
	transfer_buffer[0] \|= EXTEND_LENGTH;
	transfer_buffer[1] = (rxn_size * 8) % 256;

	if (dirtyjtag_send(context, transfer_buffer, 2 + rxn_size))
	return -1;

	if (dirtyjtag_receive(context, readarr + i, rxn_size, rxn_size) < 0)
	return -1;

	i += rxn_size;
	}

	dirtyjtag_reset_tms(context);

	return 0;
	}

	static const struct spi_master spi_master_dirtyjtag_spi = {
	.features = SPI_MASTER_4BA,
	.max_data_read = MAX_DATA_READ_UNLIMITED,
	.max_data_write = MAX_DATA_WRITE_UNLIMITED,
	.multicommand = default_spi_send_multicommand,
	.read = default_spi_read,
	.write_256 = default_spi_write_256,
	.shutdown = dirtyjtag_spi_shutdown,
	.probe_opcode = default_spi_probe_opcode,
	};

	static int dirtyjtag_spi_init(struct flashprog_programmer *const prog)
	{
	struct spi_master dirtyjtag_spi = spi_master_dirtyjtag_spi;
	struct libusb_device_handle *handle = NULL;
	struct dirtyjtag_spi_data *djtag_data = NULL;

	djtag_data = calloc(1, sizeof(struct dirtyjtag_spi_data));
	if (djtag_data == NULL) {
	msg_perr("%s: failed to allocate internal driver data structure\n", __func__);
	return -1;
	}

	int ret = libusb_init(&djtag_data->libusb_ctx);
	if (ret < 0) {
	msg_perr("%s: couldn't initialize libusb!\n", __func__);
	goto cleanup_djtag_struct;
	}

	#if LIBUSB_API_VERSION < 0x01000106
	libusb_set_debug(djtag_data->libusb_ctx, 3);
	#else
	libusb_set_option(djtag_data->libusb_ctx, LIBUSB_OPTION_LOG_LEVEL, LIBUSB_LOG_LEVEL_INFO);
	#endif

	uint16_t vid = devs_dirtyjtag_spi[0].vendor_id;
	uint16_t pid = devs_dirtyjtag_spi[0].device_id;
	handle = libusb_open_device_with_vid_pid(djtag_data->libusb_ctx, vid, pid);
	if (handle == NULL) {
	msg_perr("%s: couldn't open device %04x:%04x.\n", __func__, vid, pid);
	goto cleanup_libusb_ctx;
	}

	ret = libusb_detach_kernel_driver(handle, 0);
	if (ret != 0 && ret != LIBUSB_ERROR_NOT_FOUND) {
	msg_pwarn("Cannot detach the existing USB driver. Claiming the interface may fail. %s\n",
	libusb_error_name(ret));
	}

	ret = libusb_claim_interface(handle, 0);
	if (ret != 0) {
	msg_perr("%s: failed to claim interface 0: '%s'\n", __func__, libusb_error_name(ret));
	goto cleanup_libusb_handle;
	}

	djtag_data->libusb_handle = handle;

	unsigned long int freq = 100;
	char *tmp = extract_programmer_param("spispeed");
	if (tmp) {
	char *units = tmp;

	errno = 0;
	freq = strtoul(tmp, &units, 0);
	if (errno) {
	msg_perr("Invalid frequency \"%s\", %s\n", tmp, strerror(errno));
	free(tmp);
	goto cleanup_libusb_handle;
	}

	if (!strcasecmp(units, "hz")) {
	freq /= 1000;
	} else if (!strcasecmp(units, "khz")) {
	/* Do nothing, already in the right unit */
	} else if (!strcasecmp(units, "mhz")) {
	freq *= 1000;
	} else {
	msg_perr("Invalid unit: %s, use hz, khz or mhz\n", units);
	free(tmp);
	goto cleanup_libusb_handle;
	}

	if (freq > UINT16_MAX) {
	msg_perr("%s: Frequency set above DJTAG1/2 limits (%d kHz)\n", __func__, UINT16_MAX);
	free(tmp);
	goto cleanup_libusb_handle;
	}

	msg_pinfo("%s: programmer speed set to %lu kHz\n", __func__, freq);
	}
	free(tmp);

	char *const info = dirtyjtag_info(djtag_data);
	if (!info) {
	msg_perr("Failed to read DirtyJTAG Info.\n");
	goto cleanup_libusb_handle;
	}

	msg_pinfo("DirtyJTAG Info: %s\n", info);
	const unsigned int djtag_version = dirtyjtag_version(info);
	switch (djtag_version) {
	default:
	msg_pwarn("Warning: Unknown DJTAG version %u. Assuming DJTAG2 compatibility.\n",
	djtag_version);
	/* fall-through */
	case 2:
	dirtyjtag_spi.command = dirtyjtag_djtag2_spi_send_command;
	break;
	case 1:
	dirtyjtag_spi.command = dirtyjtag_djtag1_spi_send_command;
	break;
	}
	free(info);

	uint8_t commands[] = {
	CMD_SETSIG, /* Set TDI/TCK to low, SRST/TRST/TMS to high */
	SIG_TDI \| SIG_TMS \| SIG_TCK \| SIG_SRST \| SIG_TRST,
	SIG_SRST \| SIG_TRST \| SIG_TMS,

	CMD_FREQ, /* Set frequency */
	(freq >> 8) & 0xff,
	freq & 0xff,

	CMD_STOP,
	};
	ret = dirtyjtag_send(djtag_data, commands, sizeof(commands));
	if (ret != 0) {
	msg_perr("%s: failed to configure DirtyJTAG into initialized state\n", __func__);
	goto cleanup_libusb_handle;
	}

	return register_spi_master(&dirtyjtag_spi, 0, djtag_data);

	cleanup_libusb_handle:
	libusb_attach_kernel_driver(handle, 0);
	libusb_close(handle);

	cleanup_libusb_ctx:
	libusb_exit(djtag_data->libusb_ctx);

	cleanup_djtag_struct:
	free(djtag_data);
	return -1;
	}

	const struct programmer_entry programmer_dirtyjtag_spi = {
	.name = "dirtyjtag_spi",
	.type = USB,
	.devs.dev = devs_dirtyjtag_spi,
	.init = dirtyjtag_spi_init,
	};