path: root/chromium-twinkie-driver.patch

From 8147e36b8ffa48a23cf898332c351f6a6d85484b Mon Sep 17 00:00:00 2001
From: Vincent Palatin <vpalatin@chromium.org>
Date: Tue, 24 Jun 2014 16:35:48 -0700
Subject: [PATCH] CHROMIUM: Add driver for Chromium Twinkie dongle

Add the hardware driver to acquire both Control Channels using the
Chromium "Twinkie" dongle.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
---
 Makefile.am                              |   6 +
 configure.ac                             |   1 +
 contrib/60-libsigrok.rules               |   3 +
 src/hardware/chromium-twinkie/api.c      | 524 +++++++++++++++++++++++
 src/hardware/chromium-twinkie/protocol.c | 248 +++++++++++
 src/hardware/chromium-twinkie/protocol.h |  59 +++
 6 files changed, 841 insertions(+)
 create mode 100644 src/hardware/chromium-twinkie/api.c
 create mode 100644 src/hardware/chromium-twinkie/protocol.c
 create mode 100644 src/hardware/chromium-twinkie/protocol.h

diff --git a/Makefile.am b/Makefile.am
index 2e111e93..6478d9db 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -273,6 +273,12 @@ src_libdrivers_la_SOURCES += \
 	src/hardware/center-3xx/protocol.c \
 	src/hardware/center-3xx/api.c
 endif
+if HW_CHROMIUM_TWINKIE
+src_libdrivers_la_SOURCES += \
+	src/hardware/chromium-twinkie/protocol.h \
+	src/hardware/chromium-twinkie/protocol.c \
+	src/hardware/chromium-twinkie/api.c
+endif
 if HW_CHRONOVU_LA
 src_libdrivers_la_SOURCES += \
 	src/hardware/chronovu-la/protocol.h \
diff --git a/configure.ac b/configure.ac
index 9c42cf3b..d6ce93b5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -262,6 +262,7 @@ SR_DRIVER([BeagleLogic], [beaglelogic], [sys_mman_h sys_ioctl_h])
 SR_DRIVER([Brymen DMM], [brymen-dmm], [serial_comm])
 SR_DRIVER([CEM DT-885x], [cem-dt-885x], [serial_comm])
 SR_DRIVER([Center 3xx], [center-3xx], [serial_comm])
+SR_DRIVER([Chromium Twinkie], [chromium-twinkie], [libusb])
 SR_DRIVER([ChronoVu LA], [chronovu-la], [libusb libftdi])
 SR_DRIVER([Colead SLM], [colead-slm], [serial_comm])
 SR_DRIVER([Conrad DIGI 35 CPU], [conrad-digi-35-cpu], [serial_comm])
diff --git a/contrib/60-libsigrok.rules b/contrib/60-libsigrok.rules
index 294118cf..704dbd68 100644
--- a/contrib/60-libsigrok.rules
+++ b/contrib/60-libsigrok.rules
@@ -55,6 +55,9 @@ ATTRS{idVendor}=="16d0", ATTRS{idProduct}=="0498", ENV{ID_SIGROK}="1"
 # Brymen BU-86X adapter (e.g. for Brymen BM867/BM869 and possibly others).
 ATTRS{idVendor}=="0820", ATTRS{idProduct}=="0001", ENV{ID_SIGROK}="1"
 
+# Chromium Twinkie dongle
+ATTRS{idVendor}=="18d1", ATTRS{idProduct}=="500a", ENV{ID_SIGROK}="1"
+
 # ChronoVu LA8 (new VID/PID)
 # ChronoVu LA16 (new VID/PID)
 ATTRS{idVendor}=="0403", ATTRS{idProduct}=="8867", ENV{ID_SIGROK}="1"
diff --git a/src/hardware/chromium-twinkie/api.c b/src/hardware/chromium-twinkie/api.c
new file mode 100644
index 00000000..7e9f20a8
--- /dev/null
+++ b/src/hardware/chromium-twinkie/api.c
@@ -0,0 +1,524 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright 2014 Google, Inc
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <libusb.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+#include "protocol.h"
+
+#define TWINKIE_VID		0x18d1
+#define TWINKIE_PID		0x500a
+
+#define USB_INTERFACE		1
+#define USB_CONFIGURATION	1
+
+#define MAX_RENUM_DELAY_MS	3000
+#define NUM_SIMUL_TRANSFERS	32
+
+#define SAMPLE_RATE		SR_KHZ(2400)
+
+static const int32_t hwopts[] = {
+	SR_CONF_CONN,
+};
+
+static const int32_t hwcaps[] = {
+	SR_CONF_LOGIC_ANALYZER,
+	SR_CONF_CONTINUOUS,
+	SR_CONF_CONN | SR_CONF_GET,
+	SR_CONF_SAMPLERATE | SR_CONF_GET,
+	SR_CONF_LIMIT_SAMPLES | SR_CONF_SET,
+};
+
+static const struct chan {
+	char *name;
+	int type;
+} chan_defs[] = {
+	{"CC1", SR_CHANNEL_LOGIC},
+	{"CC2", SR_CHANNEL_LOGIC},
+
+	{NULL, 0}
+};
+
+static GSList *scan(struct sr_dev_driver *di, GSList *options)
+{
+	struct drv_context *drvc;
+	struct dev_context *devc;
+	struct sr_dev_inst *sdi;
+	struct sr_usb_dev_inst *usb;
+	struct sr_channel *ch;
+	struct sr_config *src;
+	GSList *l, *devices, *conn_devices;
+	struct libusb_device_descriptor des;
+	libusb_device **devlist;
+	int ret, i, j;
+	const char *conn;
+	char connection_id[64];
+
+	drvc = di->context;
+
+	conn = NULL;
+	for (l = options; l; l = l->next) {
+		src = l->data;
+		switch (src->key) {
+		case SR_CONF_CONN:
+			conn = g_variant_get_string(src->data, NULL);
+			break;
+		}
+	}
+	if (conn)
+		conn_devices = sr_usb_find(drvc->sr_ctx->libusb_ctx, conn);
+	else
+		conn_devices = NULL;
+
+	/* Find all Twinkie devices */
+	devices = NULL;
+	libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
+	for (i = 0; devlist[i]; i++) {
+		if (conn) {
+			usb = NULL;
+			for (l = conn_devices; l; l = l->next) {
+				usb = l->data;
+				if (usb->bus == libusb_get_bus_number(devlist[i])
+				    && usb->address == libusb_get_device_address(devlist[i]))
+					break;
+			}
+			if (!l)
+				/* This device matched none of the ones that
+				 * matched the conn specification. */
+				continue;
+		}
+
+		if ((ret = libusb_get_device_descriptor(devlist[i], &des)) != 0) {
+			sr_warn("Failed to get device descriptor: %s.",
+				libusb_error_name(ret));
+			continue;
+		}
+
+		if (des.idVendor != TWINKIE_VID || des.idProduct != TWINKIE_PID)
+			continue;
+
+		usb_get_port_path(devlist[i], connection_id, sizeof(connection_id));
+
+		sdi = g_malloc0(sizeof(struct sr_dev_inst));
+		sdi->status = SR_ST_INITIALIZING;
+		sdi->vendor = g_strdup("Chromium");
+		sdi->model = g_strdup("Twinkie");
+		sdi->driver = di;
+		sdi->connection_id = g_strdup(connection_id);
+
+		for (j = 0; chan_defs[j].name; j++)
+			if (!(ch = sr_channel_new(sdi, j, chan_defs[j].type,
+						  TRUE, chan_defs[j].name)))
+				return NULL;
+
+		if (!(devc = g_try_malloc0(sizeof(struct dev_context))))
+			return NULL;
+		sdi->priv = devc;
+		drvc->instances = g_slist_append(drvc->instances, sdi);
+		devices = g_slist_append(devices, sdi);
+
+		sr_dbg("Found a Twinkie dongle.");
+		sdi->status = SR_ST_INACTIVE;
+		sdi->inst_type = SR_INST_USB;
+		sdi->conn = sr_usb_dev_inst_new(
+			libusb_get_bus_number(devlist[i]),
+			libusb_get_device_address(devlist[i]), NULL);
+	}
+	libusb_free_device_list(devlist, 1);
+	g_slist_free_full(conn_devices, (GDestroyNotify)sr_usb_dev_inst_free);
+
+	return devices;
+}
+
+static int twinkie_dev_open(struct sr_dev_inst *sdi)
+{
+	struct sr_dev_driver *di;
+	libusb_device **devlist;
+	struct sr_usb_dev_inst *usb;
+	struct libusb_device_descriptor des;
+	struct drv_context *drvc;
+	int ret, i, device_count;
+	char connection_id[64];
+
+	di = sdi->driver;
+	drvc = di->context;
+	usb = sdi->conn;
+
+	if (sdi->status == SR_ST_ACTIVE)
+		/* Device is already in use. */
+		return SR_ERR;
+
+	device_count = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
+	if (device_count < 0) {
+		sr_err("Failed to get device list: %s.",
+		       libusb_error_name(device_count));
+		return SR_ERR;
+	}
+
+	for (i = 0; i < device_count; i++) {
+		if ((ret = libusb_get_device_descriptor(devlist[i], &des))) {
+			sr_err("Failed to get device descriptor: %s.",
+			       libusb_error_name(ret));
+			continue;
+		}
+
+		if (des.idVendor != TWINKIE_VID || des.idProduct != TWINKIE_PID)
+			continue;
+
+		if ((sdi->status == SR_ST_INITIALIZING) ||
+				(sdi->status == SR_ST_INACTIVE)) {
+			/*
+			 * Check device by its physical USB bus/port address.
+			 */
+			usb_get_port_path(devlist[i], connection_id, sizeof(connection_id));
+			if (strcmp(sdi->connection_id, connection_id))
+				/* This is not the one. */
+				continue;
+		}
+
+		if (!(ret = libusb_open(devlist[i], &usb->devhdl))) {
+			if (usb->address == 0xff)
+				/*
+				 * First time we touch this device after FW
+				 * upload, so we don't know the address yet.
+				 */
+				usb->address = libusb_get_device_address(devlist[i]);
+		} else {
+			sr_err("Failed to open device: %s.",
+			       libusb_error_name(ret));
+			break;
+		}
+
+		ret = libusb_claim_interface(usb->devhdl, USB_INTERFACE);
+		if (ret == LIBUSB_ERROR_BUSY) {
+			sr_err("Unable to claim USB interface. Another "
+			       "program or driver has already claimed it.");
+			break;
+		} else if (ret == LIBUSB_ERROR_NO_DEVICE) {
+			sr_err("Device has been disconnected.");
+			break;
+		} else if (ret != 0) {
+			sr_err("Unable to claim interface: %s.",
+			       libusb_error_name(ret));
+			break;
+		}
+
+		if ((ret = twinkie_init_device(sdi)) != SR_OK) {
+			sr_err("Failed to init device.");
+			break;
+		}
+
+		sdi->status = SR_ST_ACTIVE;
+		sr_info("Opened device %d.%d, interface %d.",
+			usb->bus, usb->address, USB_INTERFACE);
+
+		break;
+	}
+	libusb_free_device_list(devlist, 1);
+
+	if (sdi->status != SR_ST_ACTIVE) {
+		if (usb->devhdl) {
+			libusb_release_interface(usb->devhdl, USB_INTERFACE);
+			libusb_close(usb->devhdl);
+			usb->devhdl = NULL;
+		}
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
+
+static int dev_open(struct sr_dev_inst *sdi)
+{
+	int ret;
+
+	ret = twinkie_dev_open(sdi);
+	if (ret != SR_OK) {
+		sr_err("Unable to open device.");
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
+
+static int dev_close(struct sr_dev_inst *sdi)
+{
+	struct sr_usb_dev_inst *usb;
+
+	usb = sdi->conn;
+	if (usb->devhdl == NULL)
+		return SR_ERR;
+
+	sr_info("Closing device %d.%d interface %d.",
+		usb->bus, usb->address, USB_INTERFACE);
+	libusb_release_interface(usb->devhdl, USB_INTERFACE);
+	libusb_close(usb->devhdl);
+	usb->devhdl = NULL;
+	sdi->status = SR_ST_INACTIVE;
+
+	return SR_OK;
+}
+
+static int dev_clear(const struct sr_dev_driver *di)
+{
+	return std_dev_clear(di, NULL);
+}
+
+static int config_get(uint32_t key, GVariant **data,
+		const struct sr_dev_inst *sdi,
+		const struct sr_channel_group *cg)
+{
+	struct sr_usb_dev_inst *usb;
+	char str[128];
+	int ret;
+
+	(void)cg;
+
+	ret = SR_OK;
+	switch (key) {
+	case SR_CONF_CONN:
+		if (!sdi || !sdi->conn)
+			return SR_ERR_ARG;
+		usb = sdi->conn;
+		if (usb->address == 255)
+			/* Device still needs to re-enumerate after firmware
+			 * upload, so we don't know its (future) address. */
+			return SR_ERR;
+		snprintf(str, 128, "%d.%d", usb->bus, usb->address);
+		*data = g_variant_new_string(str);
+		break;
+	case SR_CONF_SAMPLERATE:
+		*data = g_variant_new_uint64(SAMPLE_RATE);
+		break;
+	default:
+		return SR_ERR_NA;
+	}
+
+	return ret;
+}
+
+static int config_set(uint32_t key, GVariant *data,
+		const struct sr_dev_inst *sdi,
+		const struct sr_channel_group *cg)
+{
+	struct dev_context *devc;
+	int ret;
+
+	(void)cg;
+
+	if (sdi->status != SR_ST_ACTIVE)
+		return SR_ERR_DEV_CLOSED;
+
+	devc = sdi->priv;
+
+	ret = SR_OK;
+	switch (key) {
+	case SR_CONF_LIMIT_SAMPLES:
+		devc->limit_samples = g_variant_get_uint64(data);
+		break;
+	default:
+		ret = SR_ERR_NA;
+	}
+
+	return ret;
+}
+
+static int config_list(uint32_t key, GVariant **data,
+		const struct sr_dev_inst *sdi,
+		const struct sr_channel_group *cg)
+{
+	int ret;
+
+	(void)sdi;
+	(void)cg;
+
+	ret = SR_OK;
+	switch (key) {
+	case SR_CONF_SCAN_OPTIONS:
+		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
+				hwopts, ARRAY_SIZE(hwopts), sizeof(int32_t));
+		break;
+	case SR_CONF_DEVICE_OPTIONS:
+		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
+				hwcaps, ARRAY_SIZE(hwcaps), sizeof(int32_t));
+		break;
+	default:
+		return SR_ERR_NA;
+	}
+
+	return ret;
+}
+
+static void abort_acquisition(struct dev_context *devc)
+{
+	int i;
+
+	devc->sent_samples = -1;
+
+	for (i = devc->num_transfers - 1; i >= 0; i--) {
+		if (devc->transfers[i])
+			libusb_cancel_transfer(devc->transfers[i]);
+	}
+}
+
+static int receive_data(int fd, int revents, void *cb_data)
+{
+	struct timeval tv;
+	struct dev_context *devc;
+	struct drv_context *drvc;
+	const struct sr_dev_inst *sdi;
+	struct sr_dev_driver *di;
+
+	(void)fd;
+	(void)revents;
+
+	sdi = cb_data;
+	di = sdi->driver;
+	drvc = di->context;
+	devc = sdi->priv;
+
+	tv.tv_sec = tv.tv_usec = 0;
+	libusb_handle_events_timeout(drvc->sr_ctx->libusb_ctx, &tv);
+
+	if (devc->sent_samples == -2) {
+		abort_acquisition(devc);
+	}
+
+	return TRUE;
+}
+
+static int dev_acquisition_start(const struct sr_dev_inst *sdi)
+{
+	struct sr_dev_driver *di = sdi->driver;
+	struct dev_context *devc;
+	struct drv_context *drvc;
+	struct sr_usb_dev_inst *usb;
+	struct libusb_transfer *transfer;
+	unsigned int i, timeout, num_transfers;
+	int ret;
+	unsigned char *buf;
+	size_t size, convsize;
+
+	if (sdi->status != SR_ST_ACTIVE)
+		return SR_ERR_DEV_CLOSED;
+
+	drvc = di->context;
+	devc = sdi->priv;
+	usb = sdi->conn;
+
+	devc->sent_samples = 0;
+	/* reset per-CC context */
+	memset(devc->cc, 0, sizeof(devc->cc));
+
+	timeout = 1000;
+	num_transfers = 10;
+	size = 10*1024;
+	convsize = size * 8 * 256 /* largest size : only rollbacks/no edges */;
+	devc->submitted_transfers = 0;
+
+	devc->convbuffer_size = convsize;
+	if (!(devc->convbuffer = g_try_malloc(convsize))) {
+		sr_err("Conversion buffer malloc failed.");
+		return SR_ERR_MALLOC;
+	}
+	memset(devc->convbuffer, 0, devc->convbuffer_size);
+
+	devc->transfers = g_try_malloc0(sizeof(*devc->transfers) * num_transfers);
+	if (!devc->transfers) {
+		sr_err("USB transfers malloc failed.");
+		g_free(devc->convbuffer);
+		return SR_ERR_MALLOC;
+	}
+
+	devc->num_transfers = num_transfers;
+	for (i = 0; i < num_transfers; i++) {
+		if (!(buf = g_try_malloc(size))) {
+			sr_err("USB transfer buffer malloc failed.");
+			if (devc->submitted_transfers)
+				abort_acquisition(devc);
+			else {
+				g_free(devc->transfers);
+				g_free(devc->convbuffer);
+			}
+			return SR_ERR_MALLOC;
+		}
+		transfer = libusb_alloc_transfer(0);
+		libusb_fill_bulk_transfer(transfer, usb->devhdl,
+				3 | LIBUSB_ENDPOINT_IN, buf, size,
+				twinkie_receive_transfer, (void *)sdi, timeout);
+		if ((ret = libusb_submit_transfer(transfer)) != 0) {
+			sr_err("Failed to submit transfer: %s.",
+			       libusb_error_name(ret));
+			libusb_free_transfer(transfer);
+			g_free(buf);
+			abort_acquisition(devc);
+			return SR_ERR;
+		}
+		devc->transfers[i] = transfer;
+		devc->submitted_transfers++;
+	}
+
+	devc->ctx = drvc->sr_ctx;
+
+	usb_source_add(sdi->session, devc->ctx, timeout, receive_data,
+		      (void *)sdi);
+
+	/* Send header packet to the session bus. */
+	std_session_send_df_header(sdi);
+
+	if ((ret = twinkie_start_acquisition(sdi)) != SR_OK) {
+		abort_acquisition(devc);
+		return ret;
+	}
+
+	return SR_OK;
+}
+
+static int dev_acquisition_stop(struct sr_dev_inst *sdi)
+{
+	if (sdi->status != SR_ST_ACTIVE)
+		return SR_ERR_DEV_CLOSED;
+
+	abort_acquisition(sdi->priv);
+
+	return SR_OK;
+}
+
+static struct sr_dev_driver chromium_twinkie_driver_info = {
+	.name = "chromium-twinkie",
+	.longname = "Chromium Twinkie",
+	.api_version = 1,
+	.init = std_init,
+	.cleanup = std_cleanup,
+	.scan = scan,
+	.dev_list = std_dev_list,
+	.dev_clear = dev_clear,
+	.config_get = config_get,
+	.config_set = config_set,
+	.config_list = config_list,
+	.dev_open = dev_open,
+	.dev_close = dev_close,
+	.dev_acquisition_start = dev_acquisition_start,
+	.dev_acquisition_stop = dev_acquisition_stop,
+};
+SR_REGISTER_DEV_DRIVER(chromium_twinkie_driver_info);
diff --git a/src/hardware/chromium-twinkie/protocol.c b/src/hardware/chromium-twinkie/protocol.c
new file mode 100644
index 00000000..e9d334d6
--- /dev/null
+++ b/src/hardware/chromium-twinkie/protocol.c
@@ -0,0 +1,248 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright 2014 Google, Inc
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdint.h>
+#include <string.h>
+#include <libusb.h>
+#include <stdio.h>
+#include <errno.h>
+#include <math.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+#include "protocol.h"
+
+SR_PRIV int twinkie_start_acquisition(const struct sr_dev_inst *sdi)
+{
+	(void)sdi;
+
+	return SR_OK;
+}
+
+SR_PRIV int twinkie_init_device(const struct sr_dev_inst *sdi)
+{
+	(void)sdi;
+
+	return SR_OK;
+}
+
+static void finish_acquisition(struct sr_dev_inst *sdi)
+{
+	struct sr_datafeed_packet packet;
+	struct dev_context *devc = sdi->priv;
+
+	/* Terminate session. */
+	packet.type = SR_DF_END;
+	sr_session_send(sdi, &packet);
+
+	/* Remove fds from polling. */
+	usb_source_remove(sdi->session, devc->ctx);
+
+	devc->num_transfers = 0;
+	g_free(devc->transfers);
+	g_free(devc->convbuffer);
+}
+
+static void free_transfer(struct libusb_transfer *transfer)
+{
+	struct sr_dev_inst *sdi;
+	struct dev_context *devc;
+	unsigned int i;
+
+	sdi = transfer->user_data;
+	devc = sdi->priv;
+
+	g_free(transfer->buffer);
+	transfer->buffer = NULL;
+	libusb_free_transfer(transfer);
+
+	for (i = 0; i < devc->num_transfers; i++) {
+		if (devc->transfers[i] == transfer) {
+			devc->transfers[i] = NULL;
+			break;
+		}
+	}
+
+	devc->submitted_transfers--;
+	if (devc->submitted_transfers == 0)
+		finish_acquisition(sdi);
+}
+
+static void export_samples(const struct sr_dev_inst *sdi, size_t cnt)
+{
+	struct sr_datafeed_packet packet;
+	struct sr_datafeed_logic logic;
+	struct dev_context *devc = sdi->priv;
+
+	/* export the received data */
+	packet.type = SR_DF_LOGIC;
+	packet.payload = &logic;
+	if (devc->limit_samples &&
+	    cnt > devc->limit_samples - devc->sent_samples)
+		cnt = devc->limit_samples - devc->sent_samples;
+	logic.length = cnt;
+	logic.unitsize = 1;
+	logic.data = devc->convbuffer;
+	sr_session_send(sdi, &packet);
+	devc->sent_samples += cnt;
+}
+
+static void expand_sample_data(const struct sr_dev_inst *sdi,
+			       const uint8_t *src, size_t srccnt)
+{
+	struct dev_context *devc = sdi->priv;
+	int i, f;
+	size_t b;
+	size_t rdy_samples, left_samples;
+	int frames = srccnt / 64;
+
+	for (f = 0; f < frames; f++) {
+		int ch = (src[1] >> 4) & 3; /* samples channel number */
+		int bit = 1 << ch; /* channel bit mask */
+		struct cc_context *cc = devc->cc + ch;
+		uint8_t *dest = devc->convbuffer + cc->idx;
+
+		if (ch >= 2) /* only acquires CCx channels */
+			continue;
+
+		/* TODO: check timestamp, overflow, sequence number */
+
+		/* skip header, go to edges data */
+		src+=4;
+		for (i = 0; i < 60; i++,src++)
+			if (*src == cc->prev_src) {
+				cc->rollbacks++;
+			} else {
+				uint8_t diff = *src - cc->prev_src;
+				int fixup = cc->rollbacks && (((int)*src < (int)cc->prev_src) || (*src == 0xff));
+				size_t total = (fixup ? cc->rollbacks - 1 : cc->rollbacks) * 256 + diff;
+
+				if (total + cc->idx > devc->convbuffer_size) {
+					sr_warn("overflow %d+%zd/%zd\n",
+						cc->idx, total,
+						devc->convbuffer_size);
+					/* reset current decoding */
+					cc->rollbacks = 0;
+					break;
+				}
+
+				/* insert bits in the buffer */
+				if (cc->level)
+					for (b = 0 ; b < total ; b++, dest++)
+						*dest |= bit;
+				else
+					dest += total;
+				cc->idx += total;
+
+				/* flip level on the next edge */
+				cc->level = ~cc->level;
+
+				cc->rollbacks = 0;
+				cc->prev_src = *src;
+			}
+		/* expand repeated rollbacks */
+		if (cc->rollbacks > 1) {
+			size_t total = 256 * (cc->rollbacks - 1);
+			if (total + cc->idx > devc->convbuffer_size) {
+				sr_warn("overflow %d+%zd/%zd\n",
+					cc->idx, total, devc->convbuffer_size);
+				/* reset current decoding */
+				total = 0;
+			}
+			/* insert bits in the buffer */
+			if (cc->level)
+				for (b = 0 ; b < total ; b++, dest++)
+					*dest |= bit ;
+			cc->idx += total;
+			cc->rollbacks = 1;
+		}
+	}
+
+	/* samples ready to be pushed (with both channels) */
+	rdy_samples = MIN(devc->cc[0].idx, devc->cc[1].idx);
+	left_samples = MAX(devc->cc[0].idx, devc->cc[1].idx) - rdy_samples;
+	/* skip empty transfer */
+	if (rdy_samples == 0)
+		return;
+
+	export_samples(sdi, rdy_samples);
+
+	/* clean up what we have sent */
+	memmove(devc->convbuffer, devc->convbuffer + rdy_samples, left_samples);
+	memset(devc->convbuffer + left_samples, 0, rdy_samples);
+	devc->cc[0].idx -= rdy_samples;
+	devc->cc[1].idx -= rdy_samples;
+}
+
+SR_PRIV void LIBUSB_CALL twinkie_receive_transfer(struct libusb_transfer *transfer)
+{
+	gboolean packet_has_error = FALSE;
+	struct sr_dev_inst *sdi;
+	struct dev_context *devc;
+
+	sdi = transfer->user_data;
+	devc = sdi->priv;
+
+	/*
+	 * If acquisition has already ended, just free any queued up
+	 * transfer that come in.
+	 */
+	if (devc->sent_samples < 0) {
+		free_transfer(transfer);
+		return;
+	}
+
+	if (transfer->status || transfer->actual_length)
+		sr_info("receive_transfer(): status %d received %d bytes.",
+			transfer->status, transfer->actual_length);
+
+	switch (transfer->status) {
+	case LIBUSB_TRANSFER_NO_DEVICE:
+		devc->sent_samples = -2;
+		free_transfer(transfer);
+		return;
+	case LIBUSB_TRANSFER_COMPLETED:
+	case LIBUSB_TRANSFER_TIMED_OUT: /* We may have received some data though. */
+		break;
+	default:
+		packet_has_error = TRUE;
+		break;
+	}
+
+	if (transfer->actual_length % 64) {
+		sr_err("Bad USB packet size.");
+		packet_has_error = TRUE;
+	}
+
+	if (transfer->actual_length == 0 || packet_has_error)
+		goto resubmit;
+
+	/* decode received edges */
+	expand_sample_data(sdi, transfer->buffer, transfer->actual_length);
+
+	if (devc->limit_samples &&
+			(uint64_t)devc->sent_samples >= devc->limit_samples) {
+		devc->sent_samples = -2;
+		free_transfer(transfer);
+		return;
+	}
+resubmit:
+	if (libusb_submit_transfer(transfer) != LIBUSB_SUCCESS)
+		free_transfer(transfer);
+}
diff --git a/src/hardware/chromium-twinkie/protocol.h b/src/hardware/chromium-twinkie/protocol.h
new file mode 100644
index 00000000..8ed6987b
--- /dev/null
+++ b/src/hardware/chromium-twinkie/protocol.h
@@ -0,0 +1,59 @@
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright 2014 Google, Inc
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBSIGROK_HARDWARE_CHROMIUM_TWINKIE_PROTOCOL_H
+#define LIBSIGROK_HARDWARE_CHROMIUM_TWINKIE_PROTOCOL_H
+
+#include <stdint.h>
+#include <glib.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+
+#define LOG_PREFIX "twinkie"
+
+/** Private, per-CC logical channel context. */
+struct cc_context {
+	int idx;
+	int rollbacks;
+	uint8_t prev_src;
+	uint8_t level;
+};
+
+/** Private, per-device-instance driver context. */
+struct dev_context {
+	/** Maximum number of samples to capture, if nonzero. */
+	uint64_t limit_samples;
+
+	int64_t sent_samples;
+	int submitted_transfers;
+	uint8_t *convbuffer;
+	size_t convbuffer_size;
+
+	unsigned int num_transfers;
+	struct libusb_transfer **transfers;
+	struct sr_context *ctx;
+
+	struct cc_context cc[2];
+};
+
+SR_PRIV int twinkie_start_acquisition(const struct sr_dev_inst *sdi);
+SR_PRIV int twinkie_init_device(const struct sr_dev_inst *sdi);
+SR_PRIV void LIBUSB_CALL twinkie_receive_transfer(struct libusb_transfer *transfer);
+
+#endif