Add MPSSE communications layer for FTDI chips

This is a higher-level libftdi replacement for use when implementing
protocol drivers for FT2232, FT2232H or FT4232H. It takes care of device
open/close and, unlike libftdi, also MPSSE command abstraction, command
queueing, buffer handling and return data parsing.

The FTDI device is accessed through libusb-1.0 in asynchronous mode.

Change-Id: I051adb574dcc39f8ca9cd7f6dbe6ae4aeea5f4c8
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/451
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>
Reviewed-by: Peter Stuge <peter@stuge.se>

2 files changed, 917 insertions, 0 deletions

diff --git a/src/jtag/drivers/mpsse.c b/src/jtag/drivers/mpsse.c
new file mode 100644
index 00000000..dbca535f
--- /dev/null
+++ b/src/jtag/drivers/mpsse.c
@@ -0,0 +1,838 @@
+/**************************************************************************
+ *   Copyright (C) 2012 by Andreas Fritiofson                              *
+ *   andreas.fritiofson@gmail.com                                          *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "mpsse.h"
+#include "helper/log.h"
+#include <libusb-1.0/libusb.h>
+
+/* Compatibility define for older libusb-1.0 */
+#ifndef LIBUSB_CALL
+#define LIBUSB_CALL
+#endif
+
+#ifdef _DEBUG_JTAG_IO_
+#define DEBUG_IO(expr...) LOG_DEBUG(expr)
+#define DEBUG_PRINT_BUF(buf, len) \
+	do { \
+		char buf_string[32 * 3 + 1]; \
+		int buf_string_pos = 0; \
+		for (int i = 0; i < len; i++) { \
+			buf_string_pos += sprintf(buf_string + buf_string_pos, " %02x", buf[i]); \
+			if (i % 32 == 32 - 1) { \
+				LOG_DEBUG("%s", buf_string); \
+				buf_string_pos = 0; \
+			} \
+		} \
+		if (buf_string_pos > 0) \
+			LOG_DEBUG("%s", buf_string);\
+	} while (0)
+#else
+#define DEBUG_IO(expr...) do {} while (0)
+#define DEBUG_PRINT_BUF(buf, len) do {} while (0)
+#endif
+
+#define FTDI_DEVICE_OUT_REQTYPE (LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE)
+#define FTDI_DEVICE_IN_REQTYPE (0x80 | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE)
+
+#define BITMODE_MPSSE 0x02
+
+#define SIO_RESET_REQUEST             0x00
+#define SIO_SET_LATENCY_TIMER_REQUEST 0x09
+#define SIO_GET_LATENCY_TIMER_REQUEST 0x0A
+#define SIO_SET_BITMODE_REQUEST       0x0B
+
+#define SIO_RESET_SIO 0
+#define SIO_RESET_PURGE_RX 1
+#define SIO_RESET_PURGE_TX 2
+
+struct mpsse_ctx {
+	libusb_context *usb_ctx;
+	libusb_device_handle *usb_dev;
+	unsigned int usb_write_timeout;
+	unsigned int usb_read_timeout;
+	uint8_t in_ep;
+	uint8_t out_ep;
+	uint16_t max_packet_size;
+	uint16_t index;
+	uint8_t interface;
+	enum ftdi_chip_type type;
+	uint8_t *write_buffer;
+	unsigned write_size;
+	unsigned write_count;
+	uint8_t *read_buffer;
+	unsigned read_size;
+	unsigned read_count;
+	uint8_t *read_chunk;
+	unsigned read_chunk_size;
+	struct bit_copy_queue read_queue;
+};
+
+/* Returns true if the string descriptor indexed by str_index in device matches string */
+static bool string_descriptor_equal(libusb_device_handle *device, uint8_t str_index,
+	const char *string)
+{
+	int retval;
+	char desc_string[256]; /* Max size of string descriptor */
+	retval = libusb_get_string_descriptor_ascii(device, str_index, (unsigned char *)desc_string,
+			sizeof(desc_string));
+	if (retval < 0) {
+		LOG_ERROR("libusb_get_string_descriptor_ascii() failed with %d", retval);
+		return false;
+	}
+	return strncmp(string, desc_string, sizeof(desc_string)) == 0;
+}
+
+/* Helper to open a libusb device that matches vid, pid, product string and/or serial string.
+ * Set any field to 0 as a wildcard. If the device is found true is returned, with ctx containing
+ * the already opened handle. ctx->interface must be set to the desired interface (channel) number
+ * prior to calling this function. */
+static bool open_matching_device(struct mpsse_ctx *ctx, const uint16_t *vid, const uint16_t *pid,
+	const char *product, const char *serial)
+{
+	libusb_device **list;
+	struct libusb_device_descriptor desc;
+	struct libusb_config_descriptor *config0;
+	int err;
+	bool found = false;
+	ssize_t cnt = libusb_get_device_list(ctx->usb_ctx, &list);
+	if (cnt < 0)
+		LOG_ERROR("libusb_get_device_list() failed with %zi", cnt);
+
+	for (ssize_t i = 0; i < cnt; i++) {
+		libusb_device *device = list[i];
+
+		err = libusb_get_device_descriptor(device, &desc);
+		if (err != LIBUSB_SUCCESS) {
+			LOG_ERROR("libusb_get_device_descriptor() failed with %d", err);
+			continue;
+		}
+
+		if (vid && *vid != desc.idVendor)
+			continue;
+		if (pid && *pid != desc.idProduct)
+			continue;
+
+		err = libusb_open(device, &ctx->usb_dev);
+		if (err != LIBUSB_SUCCESS) {
+			LOG_ERROR("libusb_open() failed with %d", err);
+			continue;
+		}
+
+		if (product && !string_descriptor_equal(ctx->usb_dev, desc.iProduct, product)) {
+			libusb_close(ctx->usb_dev);
+			continue;
+		}
+
+		if (serial && !string_descriptor_equal(ctx->usb_dev, desc.iSerialNumber, serial)) {
+			libusb_close(ctx->usb_dev);
+			continue;
+		}
+
+		found = true;
+		break;
+	}
+
+	libusb_free_device_list(list, 1);
+
+	if (!found) {
+		LOG_ERROR("no device found");
+		return false;
+	}
+
+	err = libusb_get_config_descriptor(libusb_get_device(ctx->usb_dev), 0, &config0);
+	if (err != LIBUSB_SUCCESS) {
+		LOG_ERROR("libusb_get_config_descriptor() failed with %d", err);
+		libusb_close(ctx->usb_dev);
+		return false;
+	}
+
+	/* Make sure the first configuration is selected */
+	int cfg;
+	err = libusb_get_configuration(ctx->usb_dev, &cfg);
+	if (err != LIBUSB_SUCCESS) {
+		LOG_ERROR("libusb_get_configuration() failed with %d", err);
+		goto error;
+	}
+
+	if (desc.bNumConfigurations > 0 && cfg != config0->bConfigurationValue) {
+		err = libusb_set_configuration(ctx->usb_dev, config0->bConfigurationValue);
+		if (err != LIBUSB_SUCCESS) {
+			LOG_ERROR("libusb_set_configuration() failed with %d", err);
+			goto error;
+		}
+	}
+
+	/* Try to detach ftdi_sio kernel module */
+	err = libusb_detach_kernel_driver(ctx->usb_dev, ctx->interface);
+	if (err != LIBUSB_SUCCESS && err != LIBUSB_ERROR_NOT_FOUND
+			&& err != LIBUSB_ERROR_NOT_SUPPORTED) {
+		LOG_ERROR("libusb_detach_kernel_driver() failed with %d", err);
+		goto error;
+	}
+
+	err = libusb_claim_interface(ctx->usb_dev, ctx->interface);
+	if (err != LIBUSB_SUCCESS) {
+		LOG_ERROR("libusb_claim_interface() failed with %d", err);
+		goto error;
+	}
+
+	/* Reset FTDI device */
+	err = libusb_control_transfer(ctx->usb_dev, FTDI_DEVICE_OUT_REQTYPE,
+			SIO_RESET_REQUEST, SIO_RESET_SIO,
+			ctx->index, NULL, 0, ctx->usb_write_timeout);
+	if (err < 0) {
+		LOG_ERROR("failed to reset FTDI device: %d", err);
+		goto error;
+	}
+
+	switch (desc.bcdDevice) {
+	case 0x500:
+		ctx->type = TYPE_FT2232C;
+		break;
+	case 0x700:
+		ctx->type = TYPE_FT2232H;
+		break;
+	case 0x800:
+		ctx->type = TYPE_FT4232H;
+		break;
+	default:
+		LOG_ERROR("unsupported FTDI chip type: 0x%04x", desc.bcdDevice);
+		goto error;
+	}
+
+	/* Determine maximum packet size and endpoint addresses */
+	if (!(desc.bNumConfigurations > 0 && ctx->interface < config0->bNumInterfaces
+			&& config0->interface[ctx->interface].num_altsetting > 0))
+		goto desc_error;
+
+	const struct libusb_interface_descriptor *descriptor;
+	descriptor = &config0->interface[ctx->interface].altsetting[0];
+	if (descriptor->bNumEndpoints != 2)
+		goto desc_error;
+
+	ctx->in_ep = 0;
+	ctx->out_ep = 0;
+	for (int i = 0; i < descriptor->bNumEndpoints; i++) {
+		if (descriptor->endpoint[i].bEndpointAddress & 0x80) {
+			ctx->in_ep = descriptor->endpoint[i].bEndpointAddress;
+			ctx->max_packet_size =
+					descriptor->endpoint[i].wMaxPacketSize;
+		} else {
+			ctx->out_ep = descriptor->endpoint[i].bEndpointAddress;
+		}
+	}
+
+	if (ctx->in_ep == 0 || ctx->out_ep == 0)
+		goto desc_error;
+
+	libusb_free_config_descriptor(config0);
+	return true;
+
+desc_error:
+	LOG_ERROR("unrecognized USB device descriptor");
+error:
+	libusb_free_config_descriptor(config0);
+	libusb_close(ctx->usb_dev);
+	return false;
+}
+
+struct mpsse_ctx *mpsse_open(const uint16_t *vid, const uint16_t *pid, const char *description,
+	const char *serial, int channel)
+{
+	struct mpsse_ctx *ctx = calloc(1, sizeof(*ctx));
+	int err;
+
+	if (!ctx)
+		return 0;
+
+	bit_copy_queue_init(&ctx->read_queue);
+	ctx->read_chunk_size = 16384;
+	ctx->read_size = 16384;
+	ctx->write_size = 16384;
+	ctx->read_chunk = malloc(ctx->read_chunk_size);
+	ctx->read_buffer = malloc(ctx->read_size);
+	ctx->write_buffer = malloc(ctx->write_size);
+	if (!ctx->read_chunk || !ctx->read_buffer || !ctx->write_buffer)
+		goto error;
+
+	ctx->interface = channel;
+	ctx->index = channel + 1;
+	ctx->usb_read_timeout = 5000;
+	ctx->usb_write_timeout = 5000;
+
+	err = libusb_init(&ctx->usb_ctx);
+	if (err != LIBUSB_SUCCESS) {
+		LOG_ERROR("libusb_init() failed with %d", err);
+		goto error;
+	}
+
+	if (!open_matching_device(ctx, vid, pid, description, serial)) {
+		/* Four hex digits plus terminating zero each */
+		char vidstr[5];
+		char pidstr[5];
+		LOG_ERROR("unable to open ftdi device with vid %s, pid %s, description '%s' and "
+				"serial '%s'",
+				vid ? sprintf(vidstr, "%04x", *vid), vidstr : "*",
+				pid ? sprintf(pidstr, "%04x", *pid), pidstr : "*",
+				description ? description : "*",
+				serial ? serial : "*");
+		ctx->usb_dev = 0;
+		goto error;
+	}
+
+	err = libusb_control_transfer(ctx->usb_dev, FTDI_DEVICE_OUT_REQTYPE,
+			SIO_SET_LATENCY_TIMER_REQUEST, 255, ctx->index, NULL, 0,
+			ctx->usb_write_timeout);
+	if (err < 0) {
+		LOG_ERROR("unable to set latency timer: %d", err);
+		goto error;
+	}
+
+	err = libusb_control_transfer(ctx->usb_dev,
+			FTDI_DEVICE_OUT_REQTYPE,
+			SIO_SET_BITMODE_REQUEST,
+			0x0b | (BITMODE_MPSSE << 8),
+			ctx->index,
+			NULL,
+			0,
+			ctx->usb_write_timeout);
+	if (err < 0) {
+		LOG_ERROR("unable to set MPSSE bitmode: %d", err);
+		goto error;
+	}
+
+	mpsse_purge(ctx);
+
+	return ctx;
+error:
+	mpsse_close(ctx);
+	return 0;
+}
+
+void mpsse_close(struct mpsse_ctx *ctx)
+{
+	if (ctx->usb_dev)
+		libusb_close(ctx->usb_dev);
+	if (ctx->usb_ctx)
+		libusb_exit(ctx->usb_ctx);
+	bit_copy_discard(&ctx->read_queue);
+	if (ctx->write_buffer)
+		free(ctx->write_buffer);
+	if (ctx->read_buffer)
+		free(ctx->read_buffer);
+	if (ctx->read_chunk)
+		free(ctx->read_chunk);
+
+	free(ctx);
+}
+
+bool mpsse_is_high_speed(struct mpsse_ctx *ctx)
+{
+	return ctx->type != TYPE_FT2232C;
+}
+
+void mpsse_purge(struct mpsse_ctx *ctx)
+{
+	int err;
+	LOG_DEBUG("-");
+	ctx->write_count = 0;
+	ctx->read_count = 0;
+	bit_copy_discard(&ctx->read_queue);
+	err = libusb_control_transfer(ctx->usb_dev, FTDI_DEVICE_OUT_REQTYPE, SIO_RESET_REQUEST,
+			SIO_RESET_PURGE_RX, ctx->index, NULL, 0, ctx->usb_write_timeout);
+	if (err < 0) {
+		LOG_ERROR("unable to purge ftdi rx buffers: %d", err);
+		return;
+	}
+
+	err = libusb_control_transfer(ctx->usb_dev, FTDI_DEVICE_OUT_REQTYPE, SIO_RESET_REQUEST,
+			SIO_RESET_PURGE_TX, ctx->index, NULL, 0, ctx->usb_write_timeout);
+	if (err < 0) {
+		LOG_ERROR("unable to purge ftdi tx buffers: %d", err);
+		return;
+	}
+}
+
+static unsigned buffer_write_space(struct mpsse_ctx *ctx)
+{
+	/* Reserve one byte for SEND_IMMEDIATE */
+	return ctx->write_size - ctx->write_count - 1;
+}
+
+static unsigned buffer_read_space(struct mpsse_ctx *ctx)
+{
+	return ctx->read_size - ctx->read_count;
+}
+
+static void buffer_write_byte(struct mpsse_ctx *ctx, uint8_t data)
+{
+	DEBUG_IO("%02x", data);
+	assert(ctx->write_count < ctx->write_size);
+	ctx->write_buffer[ctx->write_count++] = data;
+}
+
+static unsigned buffer_write(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset,
+	unsigned bit_count)
+{
+	DEBUG_IO("%d bits", bit_count);
+	assert(ctx->write_count + DIV_ROUND_UP(bit_count, 8) <= ctx->write_size);
+	bit_copy(ctx->write_buffer + ctx->write_count, 0, out, out_offset, bit_count);
+	ctx->write_count += DIV_ROUND_UP(bit_count, 8);
+	return bit_count;
+}
+
+static unsigned buffer_add_read(struct mpsse_ctx *ctx, uint8_t *in, unsigned in_offset,
+	unsigned bit_count, unsigned offset)
+{
+	DEBUG_IO("%d bits, offset %d", bit_count, offset);
+	assert(ctx->read_count + DIV_ROUND_UP(bit_count, 8) <= ctx->read_size);
+	bit_copy_queued(&ctx->read_queue, in, in_offset, ctx->read_buffer + ctx->read_count, offset,
+		bit_count);
+	ctx->read_count += DIV_ROUND_UP(bit_count, 8);
+	return bit_count;
+}
+
+int mpsse_clock_data_out(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset,
+	unsigned length, uint8_t mode)
+{
+	return mpsse_clock_data(ctx, out, out_offset, 0, 0, length, mode);
+}
+
+int mpsse_clock_data_in(struct mpsse_ctx *ctx, uint8_t *in, unsigned in_offset, unsigned length,
+	uint8_t mode)
+{
+	return mpsse_clock_data(ctx, 0, 0, in, in_offset, length, mode);
+}
+
+int mpsse_clock_data(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset, uint8_t *in,
+	unsigned in_offset, unsigned length, uint8_t mode)
+{
+	/* TODO: Fix MSB first modes */
+	DEBUG_IO("%s%s %d bits", in ? "in" : "", out ? "out" : "", length);
+	int retval = ERROR_OK;
+
+	/* TODO: On H chips, use command 0x8E/0x8F if in and out are both 0 */
+	if (out || (!out && !in))
+		mode |= 0x10;
+	if (in)
+		mode |= 0x20;
+
+	while (length > 0) {
+		/* Guarantee buffer space enough for a minimum size transfer */
+		if (buffer_write_space(ctx) + (length < 8) < (out ? 4 : 3)
+		    || (in && buffer_read_space(ctx) < 1))
+			retval = mpsse_flush(ctx);
+
+		if (length < 8) {
+			/* Transfer remaining bits in bit mode */
+			buffer_write_byte(ctx, 0x02 | mode);
+			buffer_write_byte(ctx, length - 1);
+			if (out)
+				out_offset += buffer_write(ctx, out, out_offset, length);
+			if (in)
+				in_offset += buffer_add_read(ctx, in, in_offset, length, 8 - length);
+			if (!out && !in)
+				buffer_write_byte(ctx, 0x00);
+			length = 0;
+		} else {
+			/* Byte transfer */
+			unsigned this_bytes = length / 8;
+			/* MPSSE command limit */
+			if (this_bytes > 65536)
+				this_bytes = 65536;
+			/* Buffer space limit. We already made sure there's space for the minimum
+			 *transfer. */
+			if (out && this_bytes + 3 > buffer_write_space(ctx))
+				this_bytes = buffer_write_space(ctx) - 3;
+			if (in && this_bytes > buffer_read_space(ctx))
+				this_bytes = buffer_read_space(ctx);
+
+			if (this_bytes > 0) {
+				buffer_write_byte(ctx, mode);
+				buffer_write_byte(ctx, (this_bytes - 1) & 0xff);
+				buffer_write_byte(ctx, (this_bytes - 1) >> 8);
+				if (out)
+					out_offset += buffer_write(ctx,
+							out,
+							out_offset,
+							this_bytes * 8);
+				if (in)
+					in_offset += buffer_add_read(ctx,
+							in,
+							in_offset,
+							this_bytes * 8,
+							0);
+				if (!out && !in)
+					for (unsigned n = 0; n < this_bytes; n++)
+						buffer_write_byte(ctx, 0x00);
+				length -= this_bytes * 8;
+			}
+		}
+	}
+	return retval;
+}
+
+int mpsse_clock_tms_cs_out(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset,
+	unsigned length, bool tdi, uint8_t mode)
+{
+	return mpsse_clock_tms_cs(ctx, out, out_offset, 0, 0, length, tdi, mode);
+}
+
+int mpsse_clock_tms_cs(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset, uint8_t *in,
+	unsigned in_offset, unsigned length, bool tdi, uint8_t mode)
+{
+	DEBUG_IO("%sout %d bits, tdi=%d", in ? "in" : "", length, tdi);
+	assert(out);
+	int retval = ERROR_OK;
+
+	mode |= 0x42;
+	if (in)
+		mode |= 0x20;
+
+	while (length > 0) {
+		/* Guarantee buffer space enough for a minimum size transfer */
+		if (buffer_write_space(ctx) < 3 || (in && buffer_read_space(ctx) < 1))
+			retval = mpsse_flush(ctx);
+
+		/* Byte transfer */
+		unsigned this_bits = length;
+		/* MPSSE command limit */
+		/* NOTE: there's a report of an FT2232 bug in this area, where shifting
+		 * exactly 7 bits can make problems with TMS signaling for the last
+		 * clock cycle:
+		 *
+		 * http://developer.intra2net.com/mailarchive/html/libftdi/2009/msg00292.html
+		 */
+		if (this_bits > 7)
+			this_bits = 7;
+
+		if (this_bits > 0) {
+			buffer_write_byte(ctx, mode);
+			buffer_write_byte(ctx, this_bits - 1);
+			uint8_t data = 0;
+			/* TODO: Fix MSB first, if allowed in MPSSE */
+			bit_copy(&data, 0, out, out_offset, this_bits);
+			out_offset += this_bits;
+			buffer_write_byte(ctx, data | (tdi ? 0x80 : 0x00));
+			if (in)
+				in_offset += buffer_add_read(ctx,
+						in,
+						in_offset,
+						this_bits,
+						8 - this_bits);
+			length -= this_bits;
+		}
+	}
+	return retval;
+}
+
+int mpsse_set_data_bits_low_byte(struct mpsse_ctx *ctx, uint8_t data, uint8_t dir)
+{
+	DEBUG_IO("-");
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 3)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, 0x80);
+	buffer_write_byte(ctx, data);
+	buffer_write_byte(ctx, dir);
+
+	return retval;
+}
+
+int mpsse_set_data_bits_high_byte(struct mpsse_ctx *ctx, uint8_t data, uint8_t dir)
+{
+	DEBUG_IO("-");
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 3)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, 0x82);
+	buffer_write_byte(ctx, data);
+	buffer_write_byte(ctx, dir);
+
+	return retval;
+}
+
+int mpsse_read_data_bits_low_byte(struct mpsse_ctx *ctx, uint8_t *data)
+{
+	DEBUG_IO("-");
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 1)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, 0x81);
+	buffer_add_read(ctx, data, 0, 8, 0);
+
+	return retval;
+}
+
+int mpsse_read_data_bits_high_byte(struct mpsse_ctx *ctx, uint8_t *data)
+{
+	DEBUG_IO("-");
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 1)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, 0x83);
+	buffer_add_read(ctx, data, 0, 8, 0);
+
+	return retval;
+}
+
+static int single_byte_boolean_helper(struct mpsse_ctx *ctx, bool var, uint8_t val_if_true,
+	uint8_t val_if_false)
+{
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 1)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, var ? val_if_true : val_if_false);
+
+	return retval;
+}
+
+int mpsse_loopback_config(struct mpsse_ctx *ctx, bool enable)
+{
+	LOG_DEBUG("%s", enable ? "on" : "off");
+	return single_byte_boolean_helper(ctx, enable, 0x84, 0x85);
+}
+
+int mpsse_set_divisor(struct mpsse_ctx *ctx, uint16_t divisor)
+{
+	LOG_DEBUG("%d", divisor);
+	int retval = ERROR_OK;
+
+	if (buffer_write_space(ctx) < 3)
+		retval = mpsse_flush(ctx);
+
+	buffer_write_byte(ctx, 0x86);
+	buffer_write_byte(ctx, divisor & 0xff);
+	buffer_write_byte(ctx, divisor >> 8);
+
+	return retval;
+}
+
+int mpsse_divide_by_5_config(struct mpsse_ctx *ctx, bool enable)
+{
+	if (!mpsse_is_high_speed(ctx))
+		return ERROR_FAIL;
+
+	LOG_DEBUG("%s", enable ? "on" : "off");
+
+	return single_byte_boolean_helper(ctx, enable, 0x8b, 0x8a);
+}
+
+int mpsse_rtck_config(struct mpsse_ctx *ctx, bool enable)
+{
+	if (!mpsse_is_high_speed(ctx))
+		return ERROR_FAIL;
+
+	LOG_DEBUG("%s", enable ? "on" : "off");
+
+	return single_byte_boolean_helper(ctx, enable, 0x96, 0x97);
+}
+
+int mpsse_set_frequency(struct mpsse_ctx *ctx, int frequency)
+{
+	LOG_DEBUG("target %d Hz", frequency);
+	assert(frequency >= 0);
+	int base_clock;
+
+	if (frequency == 0)
+		return mpsse_rtck_config(ctx, true);
+
+	mpsse_rtck_config(ctx, false); /* just try */
+
+	if (frequency > 60000000 / 2 / 65536 && mpsse_is_high_speed(ctx)) {
+		int retval = mpsse_divide_by_5_config(ctx, false);
+		if (retval != ERROR_OK)
+			return retval;
+		base_clock = 60000000;
+	} else {
+		mpsse_divide_by_5_config(ctx, true); /* just try */
+		base_clock = 12000000;
+	}
+
+	int divisor = (base_clock / 2 + frequency - 1) / frequency - 1;
+	if (divisor > 65535)
+		divisor = 65535;
+	assert(divisor >= 0);
+
+	int retval = mpsse_set_divisor(ctx, divisor);
+	if (retval != ERROR_OK)
+		return retval;
+
+	frequency = base_clock / 2 / (1 + divisor);
+	LOG_DEBUG("actually %d Hz", frequency);
+
+	return frequency;
+}
+
+/* Context needed by the callbacks */
+struct transfer_result {
+	struct mpsse_ctx *ctx;
+	bool done;
+	unsigned transferred;
+};
+
+static LIBUSB_CALL void read_cb(struct libusb_transfer *transfer)
+{
+	struct transfer_result *res = (struct transfer_result *)transfer->user_data;
+	struct mpsse_ctx *ctx = res->ctx;
+
+	unsigned packet_size = ctx->max_packet_size;
+
+	DEBUG_PRINT_BUF(transfer->buffer, transfer->actual_length);
+
+	/* Strip the two status bytes sent at the beginning of each USB packet
+	 * while copying the chunk buffer to the read buffer */
+	unsigned num_packets = DIV_ROUND_UP(transfer->actual_length, packet_size);
+	unsigned chunk_remains = transfer->actual_length;
+	for (unsigned i = 0; i < num_packets && chunk_remains > 2; i++) {
+		unsigned this_size = packet_size - 2;
+		if (this_size > chunk_remains - 2)
+			this_size = chunk_remains - 2;
+		if (this_size > ctx->read_count - res->transferred)
+			this_size = ctx->read_count - res->transferred;
+		memcpy(ctx->read_buffer + res->transferred,
+			ctx->read_chunk + packet_size * i + 2,
+			this_size);
+		res->transferred += this_size;
+		chunk_remains -= this_size + 2;
+		if (res->transferred == ctx->read_count) {
+			res->done = true;
+			break;
+		}
+	}
+
+	DEBUG_IO("raw chunk %d, transferred %d of %d", transfer->actual_length, res->transferred,
+		ctx->read_count);
+
+	if (!res->done)
+		if (libusb_submit_transfer(transfer) != LIBUSB_SUCCESS)
+			res->done = true;
+}
+
+static LIBUSB_CALL void write_cb(struct libusb_transfer *transfer)
+{
+	struct transfer_result *res = (struct transfer_result *)transfer->user_data;
+	struct mpsse_ctx *ctx = res->ctx;
+
+	res->transferred += transfer->actual_length;
+
+	DEBUG_IO("transferred %d of %d", res->transferred, ctx->write_count);
+
+	DEBUG_PRINT_BUF(transfer->buffer, transfer->actual_length);
+
+	if (res->transferred == ctx->write_count)
+		res->done = true;
+	else {
+		transfer->length = ctx->write_count - res->transferred;
+		transfer->buffer = ctx->write_buffer + res->transferred;
+		if (libusb_submit_transfer(transfer) != LIBUSB_SUCCESS)
+			res->done = true;
+	}
+}
+
+int mpsse_flush(struct mpsse_ctx *ctx)
+{
+	DEBUG_IO("write %d%s, read %d", ctx->write_count, ctx->read_count ? "+1" : "",
+			ctx->read_count);
+	assert(ctx->write_count > 0 || ctx->read_count == 0); /* No read data without write data */
+	int retval = ERROR_OK;
+
+	if (ctx->write_count == 0)
+		return retval;
+
+	struct libusb_transfer *read_transfer = 0;
+	struct transfer_result read_result = { .ctx = ctx, .done = true };
+	if (ctx->read_count) {
+		buffer_write_byte(ctx, 0x87); /* SEND_IMMEDIATE */
+		read_result.done = false;
+		read_transfer = libusb_alloc_transfer(0);
+		libusb_fill_bulk_transfer(read_transfer, ctx->usb_dev, ctx->in_ep, ctx->read_chunk,
+			ctx->read_chunk_size, read_cb, &read_result,
+			ctx->usb_read_timeout);
+		retval = libusb_submit_transfer(read_transfer);
+	}
+
+	struct transfer_result write_result = { .ctx = ctx, .done = false };
+	struct libusb_transfer *write_transfer = libusb_alloc_transfer(0);
+	libusb_fill_bulk_transfer(write_transfer, ctx->usb_dev, ctx->out_ep, ctx->write_buffer,
+		ctx->write_count, write_cb, &write_result, ctx->usb_write_timeout);
+	retval = libusb_submit_transfer(write_transfer);
+
+	/* Polling loop, more or less taken from libftdi */
+	while (!write_result.done || !read_result.done) {
+		retval = libusb_handle_events(ctx->usb_ctx);
+		keep_alive();
+		if (retval != LIBUSB_SUCCESS && retval != LIBUSB_ERROR_INTERRUPTED) {
+			libusb_cancel_transfer(write_transfer);
+			if (read_transfer)
+				libusb_cancel_transfer(read_transfer);
+			while (!write_result.done || !read_result.done)
+				if (libusb_handle_events(ctx->usb_ctx) != LIBUSB_SUCCESS)
+					break;
+		}
+	}
+
+	if (retval != LIBUSB_SUCCESS) {
+		LOG_ERROR("libusb_handle_events() failed with %d", retval);
+		retval = ERROR_FAIL;
+	} else if (write_result.transferred < ctx->write_count) {
+		LOG_ERROR("ftdi device did not accept all data: %d, tried %d",
+			write_result.transferred,
+			ctx->write_count);
+		retval = ERROR_FAIL;
+	} else if (read_result.transferred < ctx->read_count) {
+		LOG_ERROR("ftdi device did not return all data: %d, expected %d",
+			read_result.transferred,
+			ctx->read_count);
+		retval = ERROR_FAIL;
+	} else if (ctx->read_count) {
+		ctx->write_count = 0;
+		ctx->read_count = 0;
+		bit_copy_execute(&ctx->read_queue);
+		retval = ERROR_OK;
+	} else {
+		ctx->write_count = 0;
+		bit_copy_discard(&ctx->read_queue);
+		retval = ERROR_OK;
+	}
+
+	libusb_free_transfer(write_transfer);
+	if (read_transfer)
+		libusb_free_transfer(read_transfer);
+
+	if (retval != ERROR_OK)
+		mpsse_purge(ctx);
+
+	return retval;
+}
diff --git a/src/jtag/drivers/mpsse.h b/src/jtag/drivers/mpsse.h
new file mode 100644
index 00000000..766a2158
--- /dev/null
+++ b/src/jtag/drivers/mpsse.h
@@ -0,0 +1,79 @@
+/**************************************************************************
+ *   Copyright (C) 2012 by Andreas Fritiofson                              *
+ *   andreas.fritiofson@gmail.com                                          *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#ifndef MPSSE_H_
+#define MPSSE_H_
+
+#include <stdbool.h>
+#include "helper/binarybuffer.h"
+
+/* Mode flags */
+#define POS_EDGE_OUT 0x00
+#define NEG_EDGE_OUT 0x01
+#define POS_EDGE_IN 0x00
+#define NEG_EDGE_IN 0x04
+#define MSB_FIRST 0x00
+#define LSB_FIRST 0x08
+
+enum ftdi_chip_type {
+	TYPE_FT2232C,
+	TYPE_FT2232H,
+	TYPE_FT4232H,
+};
+
+struct mpsse_ctx;
+
+/* Device handling */
+struct mpsse_ctx *mpsse_open(const uint16_t *vid, const uint16_t *pid, const char *description,
+	const char *serial, int channel);
+void mpsse_close(struct mpsse_ctx *ctx);
+bool mpsse_is_high_speed(struct mpsse_ctx *ctx);
+
+/* Command queuing. These correspond to the MPSSE commands with the same names, but no need to care
+ * about bit/byte transfer or data length limitation. Read data is guaranteed to be available only
+ * after the following mpsse_flush(). */
+int mpsse_clock_data_out(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset,
+			 unsigned length, uint8_t mode);
+int mpsse_clock_data_in(struct mpsse_ctx *ctx, uint8_t *in, unsigned in_offset, unsigned length,
+			uint8_t mode);
+int mpsse_clock_data(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset, uint8_t *in,
+		     unsigned in_offset, unsigned length, uint8_t mode);
+int mpsse_clock_tms_cs_out(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset,
+			   unsigned length, bool tdi, uint8_t mode);
+int mpsse_clock_tms_cs(struct mpsse_ctx *ctx, const uint8_t *out, unsigned out_offset, uint8_t *in,
+		       unsigned in_offset, unsigned length, bool tdi, uint8_t mode);
+int mpsse_set_data_bits_low_byte(struct mpsse_ctx *ctx, uint8_t data, uint8_t dir);
+int mpsse_set_data_bits_high_byte(struct mpsse_ctx *ctx, uint8_t data, uint8_t dir);
+int mpsse_read_data_bits_low_byte(struct mpsse_ctx *ctx, uint8_t *data);
+int mpsse_read_data_bits_high_byte(struct mpsse_ctx *ctx, uint8_t *data);
+int mpsse_loopback_config(struct mpsse_ctx *ctx, bool enable);
+int mpsse_set_divisor(struct mpsse_ctx *ctx, uint16_t divisor);
+int mpsse_divide_by_5_config(struct mpsse_ctx *ctx, bool enable);
+int mpsse_rtck_config(struct mpsse_ctx *ctx, bool enable);
+
+/* Helper to set frequency in Hertz. Returns actual realizable frequency or negative error.
+ * Frequency 0 means RTCK. */
+int mpsse_set_frequency(struct mpsse_ctx *ctx, int frequency);
+
+/* Queue handling */
+int mpsse_flush(struct mpsse_ctx *ctx);
+void mpsse_purge(struct mpsse_ctx *ctx);
+
+#endif /* MPSSE_H_ */