drivers/media/radio/si4713/radio-usb-si4713.c - arm/linux-arm-legacy - Git at Google

 /*
  * Copyright 2013 Cisco Systems, Inc. and/or its affiliates.
  * All rights reserved.
  *
  * This program is free software; you may redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; version 2 of the License.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */

 /* kernel includes */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/usb.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/input.h>
 #include <linux/mutex.h>
 #include <linux/i2c.h>
 /* V4l includes */
 #include <linux/videodev2.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
 #include <media/v4l2-event.h>
 #include <media/si4713.h>

 #include "si4713.h"

 /* driver and module definitions */
 MODULE_AUTHOR("Dinesh Ram <dinesh.ram@cern.ch>");
 MODULE_DESCRIPTION("Si4713 FM Transmitter USB driver");
 MODULE_LICENSE("GPL v2");

 /* The Device announces itself as Cygnal Integrated Products, Inc. */
 #define USB_SI4713_VENDOR		0x10c4
 #define USB_SI4713_PRODUCT		0x8244

 #define BUFFER_LENGTH			64
 #define USB_TIMEOUT			1000
 #define USB_RESP_TIMEOUT		50000

 /* USB Device ID List */
 static struct usb_device_id usb_si4713_usb_device_table[] = {
 	{USB_DEVICE_AND_INTERFACE_INFO(USB_SI4713_VENDOR, USB_SI4713_PRODUCT,
 							USB_CLASS_HID, 0, 0) },
 	{ }						/* Terminating entry */
 };

 MODULE_DEVICE_TABLE(usb, usb_si4713_usb_device_table);

 struct si4713_usb_device {
 	struct usb_device	*usbdev;
 	struct usb_interface	*intf;
 	struct video_device	vdev;
 	struct v4l2_device	v4l2_dev;
 	struct v4l2_subdev	*v4l2_subdev;
 	struct mutex		lock;
 	struct i2c_adapter	i2c_adapter;

 	u8			*buffer;
 };

 static inline struct si4713_usb_device *to_si4713_dev(struct v4l2_device *v4l2_dev)
 {
 	return container_of(v4l2_dev, struct si4713_usb_device, v4l2_dev);
 }

 static int vidioc_querycap(struct file *file, void *priv,
 					struct v4l2_capability *v)
 {
 	struct si4713_usb_device *radio = video_drvdata(file);

 	strlcpy(v->driver, "radio-usb-si4713", sizeof(v->driver));
 	strlcpy(v->card, "Si4713 FM Transmitter", sizeof(v->card));
 	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
 	v->device_caps = V4L2_CAP_MODULATOR | V4L2_CAP_RDS_OUTPUT;
 	v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;

 	return 0;
 }

 static int vidioc_g_modulator(struct file *file, void *priv,
 				struct v4l2_modulator *vm)
 {
 	struct si4713_usb_device *radio = video_drvdata(file);

 	return v4l2_subdev_call(radio->v4l2_subdev, tuner, g_modulator, vm);
 }

 static int vidioc_s_modulator(struct file *file, void *priv,
 				const struct v4l2_modulator *vm)
 {
 	struct si4713_usb_device *radio = video_drvdata(file);

 	return v4l2_subdev_call(radio->v4l2_subdev, tuner, s_modulator, vm);
 }

 static int vidioc_s_frequency(struct file *file, void *priv,
 				const struct v4l2_frequency *vf)
 {
 	struct si4713_usb_device *radio = video_drvdata(file);

 	return v4l2_subdev_call(radio->v4l2_subdev, tuner, s_frequency, vf);
 }

 static int vidioc_g_frequency(struct file *file, void *priv,
 				struct v4l2_frequency *vf)
 {
 	struct si4713_usb_device *radio = video_drvdata(file);

 	return v4l2_subdev_call(radio->v4l2_subdev, tuner, g_frequency, vf);
 }

 static const struct v4l2_ioctl_ops usb_si4713_ioctl_ops = {
 	.vidioc_querycap	  = vidioc_querycap,
 	.vidioc_g_modulator	  = vidioc_g_modulator,
 	.vidioc_s_modulator	  = vidioc_s_modulator,
 	.vidioc_g_frequency	  = vidioc_g_frequency,
 	.vidioc_s_frequency	  = vidioc_s_frequency,
 	.vidioc_log_status	  = v4l2_ctrl_log_status,
 	.vidioc_subscribe_event   = v4l2_ctrl_subscribe_event,
 	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
 };

 /* File system interface */
 static const struct v4l2_file_operations usb_si4713_fops = {
 	.owner		= THIS_MODULE,
 	.open           = v4l2_fh_open,
 	.release        = v4l2_fh_release,
 	.poll           = v4l2_ctrl_poll,
 	.unlocked_ioctl	= video_ioctl2,
 };

 static void usb_si4713_video_device_release(struct v4l2_device *v4l2_dev)
 {
 	struct si4713_usb_device *radio = to_si4713_dev(v4l2_dev);
 	struct i2c_adapter *adapter = &radio->i2c_adapter;

 	i2c_del_adapter(adapter);
 	v4l2_device_unregister(&radio->v4l2_dev);
 	kfree(radio->buffer);
 	kfree(radio);
 }

 /*
  * This command sequence emulates the behaviour of the Windows driver.
  * The structure of these commands was determined by sniffing the
  * usb traffic of the device during startup.
  * Most likely, these commands make some queries to the device.
  * Commands are sent to enquire parameters like the bus mode,
  * component revision, boot mode, the device serial number etc.
  *
  * These commands are necessary to be sent in this order during startup.
  * The device fails to powerup if these commands are not sent.
  *
  * The complete list of startup commands is given in the start_seq table below.
  */
 static int si4713_send_startup_command(struct si4713_usb_device *radio)
 {
 	unsigned long until_jiffies = jiffies + usecs_to_jiffies(USB_RESP_TIMEOUT) + 1;
 	u8 *buffer = radio->buffer;
 	int retval;

 	/* send the command */
 	retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
 					0x09, 0x21, 0x033f, 0, radio->buffer,
 					BUFFER_LENGTH, USB_TIMEOUT);
 	if (retval < 0)
 		return retval;

 	for (;;) {
 		/* receive the response */
 		retval = usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 				0x01, 0xa1, 0x033f, 0, radio->buffer,
 				BUFFER_LENGTH, USB_TIMEOUT);
 		if (retval < 0)
 			return retval;
 		if (!radio->buffer[1]) {
 			/* USB traffic sniffing showed that some commands require
 			 * additional checks. */
 			switch (buffer[1]) {
 			case 0x32:
 				if (radio->buffer[2] == 0)
 					return 0;
 				break;
 			case 0x14:
 			case 0x12:
 				if (radio->buffer[2] & SI4713_CTS)
 					return 0;
 				break;
 			case 0x06:
 				if ((radio->buffer[2] & SI4713_CTS) && radio->buffer[9] == 0x08)
 					return 0;
 				break;
 			default:
 				return 0;
 			}
 		}
 		if (time_is_before_jiffies(until_jiffies))
 			return -EIO;
 		msleep(3);
 	}

 	return retval;
 }

 struct si4713_start_seq_table {
 	int len;
 	u8 payload[8];
 };

 /*
  * Some of the startup commands that could be recognized are :
  * (0x03): Get serial number of the board (Response : CB000-00-00)
  * (0x06, 0x03, 0x03, 0x08, 0x01, 0x0f) : Get Component revision
  */
 static struct si4713_start_seq_table start_seq[] = {

 	{ 1, { 0x03 } },
 	{ 2, { 0x32, 0x7f } },
 	{ 6, { 0x06, 0x03, 0x03, 0x08, 0x01, 0x0f } },
 	{ 2, { 0x14, 0x02 } },
 	{ 2, { 0x09, 0x90 } },
 	{ 3, { 0x08, 0x90, 0xfa } },
 	{ 2, { 0x36, 0x01 } },
 	{ 2, { 0x05, 0x03 } },
 	{ 7, { 0x06, 0x00, 0x06, 0x0e, 0x01, 0x0f, 0x05 } },
 	{ 1, { 0x12 } },
 	/* Commands that are sent after pressing the 'Initialize'
 		button in the windows application */
 	{ 1, { 0x03 } },
 	{ 1, { 0x01 } },
 	{ 2, { 0x09, 0x90 } },
 	{ 3, { 0x08, 0x90, 0xfa } },
 	{ 1, { 0x34 } },
 	{ 2, { 0x35, 0x01 } },
 	{ 2, { 0x36, 0x01 } },
 	{ 2, { 0x30, 0x09 } },
 	{ 4, { 0x30, 0x06, 0x00, 0xe2 } },
 	{ 3, { 0x31, 0x01, 0x30 } },
 	{ 3, { 0x31, 0x04, 0x09 } },
 	{ 2, { 0x05, 0x02 } },
 	{ 6, { 0x06, 0x03, 0x03, 0x08, 0x01, 0x0f } },
 };

 static int si4713_start_seq(struct si4713_usb_device *radio)
 {
 	int retval = 0;
 	int i;

 	radio->buffer[0] = 0x3f;

 	for (i = 0; i < ARRAY_SIZE(start_seq); i++) {
 		int len = start_seq[i].len;
 		u8 *payload = start_seq[i].payload;

 		memcpy(radio->buffer + 1, payload, len);
 		memset(radio->buffer + len + 1, 0, BUFFER_LENGTH - 1 - len);
 		retval = si4713_send_startup_command(radio);
 	}

 	return retval;
 }

 static struct i2c_board_info si4713_board_info = {
 	I2C_BOARD_INFO("si4713", SI4713_I2C_ADDR_BUSEN_HIGH),
 };

 struct si4713_command_table {
 	int command_id;
 	u8 payload[8];
 };

 /*
  * Structure of a command :
  *	Byte 1 : 0x3f (always)
  *	Byte 2 : 0x06 (send a command)
  *	Byte 3 : Unknown
  *	Byte 4 : Number of arguments + 1 (for the command byte)
  *	Byte 5 : Number of response bytes
  */
 static struct si4713_command_table command_table[] = {

 	{ SI4713_CMD_POWER_UP,		{ 0x00, SI4713_PWUP_NARGS + 1, SI4713_PWUP_NRESP} },
 	{ SI4713_CMD_GET_REV,		{ 0x03, 0x01, SI4713_GETREV_NRESP } },
 	{ SI4713_CMD_POWER_DOWN,	{ 0x00, 0x01, SI4713_PWDN_NRESP} },
 	{ SI4713_CMD_SET_PROPERTY,	{ 0x00, SI4713_SET_PROP_NARGS + 1, SI4713_SET_PROP_NRESP } },
 	{ SI4713_CMD_GET_PROPERTY,	{ 0x00, SI4713_GET_PROP_NARGS + 1, SI4713_GET_PROP_NRESP } },
 	{ SI4713_CMD_TX_TUNE_FREQ,	{ 0x03, SI4713_TXFREQ_NARGS + 1, SI4713_TXFREQ_NRESP } },
 	{ SI4713_CMD_TX_TUNE_POWER,	{ 0x03, SI4713_TXPWR_NARGS + 1, SI4713_TXPWR_NRESP } },
 	{ SI4713_CMD_TX_TUNE_MEASURE,	{ 0x03, SI4713_TXMEA_NARGS + 1, SI4713_TXMEA_NRESP } },
 	{ SI4713_CMD_TX_TUNE_STATUS,	{ 0x00, SI4713_TXSTATUS_NARGS + 1, SI4713_TXSTATUS_NRESP } },
 	{ SI4713_CMD_TX_ASQ_STATUS,	{ 0x03, SI4713_ASQSTATUS_NARGS + 1, SI4713_ASQSTATUS_NRESP } },
 	{ SI4713_CMD_GET_INT_STATUS,	{ 0x03, 0x01, SI4713_GET_STATUS_NRESP } },
 	{ SI4713_CMD_TX_RDS_BUFF,	{ 0x03, SI4713_RDSBUFF_NARGS + 1, SI4713_RDSBUFF_NRESP } },
 	{ SI4713_CMD_TX_RDS_PS,		{ 0x00, SI4713_RDSPS_NARGS + 1, SI4713_RDSPS_NRESP } },
 };

 static int send_command(struct si4713_usb_device *radio, u8 *payload, char *data, int len)
 {
 	int retval;

 	radio->buffer[0] = 0x3f;
 	radio->buffer[1] = 0x06;

 	memcpy(radio->buffer + 2, payload, 3);
 	memcpy(radio->buffer + 5, data, len);
 	memset(radio->buffer + 5 + len, 0, BUFFER_LENGTH - 5 - len);

 	/* send the command */
 	retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
 					0x09, 0x21, 0x033f, 0, radio->buffer,
 					BUFFER_LENGTH, USB_TIMEOUT);

 	return retval < 0 ? retval : 0;
 }

 static int si4713_i2c_read(struct si4713_usb_device *radio, char *data, int len)
 {
 	unsigned long until_jiffies = jiffies + usecs_to_jiffies(USB_RESP_TIMEOUT) + 1;
 	int retval;

 	/* receive the response */
 	for (;;) {
 		retval = usb_control_msg(radio->usbdev,
 					usb_rcvctrlpipe(radio->usbdev, 0),
 					0x01, 0xa1, 0x033f, 0, radio->buffer,
 					BUFFER_LENGTH, USB_TIMEOUT);
 		if (retval < 0)
 			return retval;

 		/*
 		 * Check that we get a valid reply back (buffer[1] == 0) and
 		 * that CTS is set before returning, otherwise we wait and try
 		 * again. The i2c driver also does the CTS check, but the timeouts
 		 * used there are much too small for this USB driver, so we wait
 		 * for it here.
 		 */
 		if (radio->buffer[1] == 0 && (radio->buffer[2] & SI4713_CTS)) {
 			memcpy(data, radio->buffer + 2, len);
 			return 0;
 		}
 		if (time_is_before_jiffies(until_jiffies)) {
 			/* Zero the status value, ensuring CTS isn't set */
 			data[0] = 0;
 			return 0;
 		}
 		msleep(3);
 	}
 }

 static int si4713_i2c_write(struct si4713_usb_device *radio, char *data, int len)
 {
 	int retval = -EINVAL;
 	int i;

 	if (len > BUFFER_LENGTH - 5)
 		return -EINVAL;

 	for (i = 0; i < ARRAY_SIZE(command_table); i++) {
 		if (data[0] == command_table[i].command_id)
 			retval = send_command(radio, command_table[i].payload,
 						data, len);
 	}

 	return retval < 0 ? retval : 0;
 }

 static int si4713_transfer(struct i2c_adapter *i2c_adapter,
 				struct i2c_msg *msgs, int num)
 {
 	struct si4713_usb_device *radio = i2c_get_adapdata(i2c_adapter);
 	int retval = -EINVAL;
 	int i;

 	if (num <= 0)
 		return 0;

 	for (i = 0; i < num; i++) {
 		if (msgs[i].flags & I2C_M_RD)
 			retval = si4713_i2c_read(radio, msgs[i].buf, msgs[i].len);
 		else
 			retval = si4713_i2c_write(radio, msgs[i].buf, msgs[i].len);
 		if (retval)
 			break;
 	}

 	return retval ? retval : num;
 }

 static u32 si4713_functionality(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 static struct i2c_algorithm si4713_algo = {
 	.master_xfer   = si4713_transfer,
 	.functionality = si4713_functionality,
 };

 /* This name value shows up in the sysfs filename associated
 		with this I2C adapter */
 static struct i2c_adapter si4713_i2c_adapter_template = {
 	.name   = "si4713-i2c",
 	.owner  = THIS_MODULE,
 	.algo   = &si4713_algo,
 };

 static int si4713_register_i2c_adapter(struct si4713_usb_device *radio)
 {
 	radio->i2c_adapter = si4713_i2c_adapter_template;
 	/* set up sysfs linkage to our parent device */
 	radio->i2c_adapter.dev.parent = &radio->usbdev->dev;
 	i2c_set_adapdata(&radio->i2c_adapter, radio);

 	return i2c_add_adapter(&radio->i2c_adapter);
 }

 /* check if the device is present and register with v4l and usb if it is */
 static int usb_si4713_probe(struct usb_interface *intf,
 				const struct usb_device_id *id)
 {
 	struct si4713_usb_device *radio;
 	struct i2c_adapter *adapter;
 	struct v4l2_subdev *sd;
 	int retval = -ENOMEM;

 	dev_info(&intf->dev, "Si4713 development board discovered: (%04X:%04X)\n",
 			id->idVendor, id->idProduct);

 	/* Initialize local device structure */
 	radio = kzalloc(sizeof(struct si4713_usb_device), GFP_KERNEL);
 	if (radio)
 		radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

 	if (!radio || !radio->buffer) {
 		dev_err(&intf->dev, "kmalloc for si4713_usb_device failed\n");
 		kfree(radio);
 		return -ENOMEM;
 	}

 	mutex_init(&radio->lock);

 	radio->usbdev = interface_to_usbdev(intf);
 	radio->intf = intf;
 	usb_set_intfdata(intf, &radio->v4l2_dev);

 	retval = si4713_start_seq(radio);
 	if (retval < 0)
 		goto err_v4l2;

 	retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
 	if (retval < 0) {
 		dev_err(&intf->dev, "couldn't register v4l2_device\n");
 		goto err_v4l2;
 	}

 	retval = si4713_register_i2c_adapter(radio);
 	if (retval < 0) {
 		dev_err(&intf->dev, "could not register i2c device\n");
 		goto err_i2cdev;
 	}

 	adapter = &radio->i2c_adapter;
 	sd = v4l2_i2c_new_subdev_board(&radio->v4l2_dev, adapter,
 					  &si4713_board_info, NULL);
 	radio->v4l2_subdev = sd;
 	if (!sd) {
 		dev_err(&intf->dev, "cannot get v4l2 subdevice\n");
 		retval = -ENODEV;
 		goto del_adapter;
 	}

 	radio->vdev.ctrl_handler = sd->ctrl_handler;
 	radio->v4l2_dev.release = usb_si4713_video_device_release;
 	strlcpy(radio->vdev.name, radio->v4l2_dev.name,
 		sizeof(radio->vdev.name));
 	radio->vdev.v4l2_dev = &radio->v4l2_dev;
 	radio->vdev.fops = &usb_si4713_fops;
 	radio->vdev.ioctl_ops = &usb_si4713_ioctl_ops;
 	radio->vdev.lock = &radio->lock;
 	radio->vdev.release = video_device_release_empty;
 	radio->vdev.vfl_dir = VFL_DIR_TX;

 	video_set_drvdata(&radio->vdev, radio);
 	set_bit(V4L2_FL_USE_FH_PRIO, &radio->vdev.flags);

 	retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
 	if (retval < 0) {
 		dev_err(&intf->dev, "could not register video device\n");
 		goto del_adapter;
 	}

 	dev_info(&intf->dev, "V4L2 device registered as %s\n",
 			video_device_node_name(&radio->vdev));

 	return 0;

 del_adapter:
 	i2c_del_adapter(adapter);
 err_i2cdev:
 	v4l2_device_unregister(&radio->v4l2_dev);
 err_v4l2:
 	kfree(radio->buffer);
 	kfree(radio);
 	return retval;
 }

 static void usb_si4713_disconnect(struct usb_interface *intf)
 {
 	struct si4713_usb_device *radio = to_si4713_dev(usb_get_intfdata(intf));

 	dev_info(&intf->dev, "Si4713 development board now disconnected\n");

 	mutex_lock(&radio->lock);
 	usb_set_intfdata(intf, NULL);
 	video_unregister_device(&radio->vdev);
 	v4l2_device_disconnect(&radio->v4l2_dev);
 	mutex_unlock(&radio->lock);
 	v4l2_device_put(&radio->v4l2_dev);
 }

 /* USB subsystem interface */
 static struct usb_driver usb_si4713_driver = {
 	.name			= "radio-usb-si4713",
 	.probe			= usb_si4713_probe,
 	.disconnect		= usb_si4713_disconnect,
 	.id_table		= usb_si4713_usb_device_table,
 };

 module_usb_driver(usb_si4713_driver);
	/*
	* Copyright 2013 Cisco Systems, Inc. and/or its affiliates.
	* All rights reserved.
	*
	* This program is free software; you may redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; version 2 of the License.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
	* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
	* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	* SOFTWARE.
	*/

	/* kernel includes */
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/usb.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/input.h>
	#include <linux/mutex.h>
	#include <linux/i2c.h>
	/* V4l includes */
	#include <linux/videodev2.h>
	#include <media/v4l2-common.h>
	#include <media/v4l2-device.h>
	#include <media/v4l2-ioctl.h>
	#include <media/v4l2-event.h>
	#include <media/si4713.h>

	#include "si4713.h"

	/* driver and module definitions */
	MODULE_AUTHOR("Dinesh Ram <dinesh.ram@cern.ch>");
	MODULE_DESCRIPTION("Si4713 FM Transmitter USB driver");
	MODULE_LICENSE("GPL v2");

	/* The Device announces itself as Cygnal Integrated Products, Inc. */
	#define USB_SI4713_VENDOR 0x10c4
	#define USB_SI4713_PRODUCT 0x8244

	#define BUFFER_LENGTH 64
	#define USB_TIMEOUT 1000
	#define USB_RESP_TIMEOUT 50000

	/* USB Device ID List */
	static struct usb_device_id usb_si4713_usb_device_table[] = {
	{USB_DEVICE_AND_INTERFACE_INFO(USB_SI4713_VENDOR, USB_SI4713_PRODUCT,
	USB_CLASS_HID, 0, 0) },
	{ } /* Terminating entry */
	};

	MODULE_DEVICE_TABLE(usb, usb_si4713_usb_device_table);

	struct si4713_usb_device {
	struct usb_device *usbdev;
	struct usb_interface *intf;
	struct video_device vdev;
	struct v4l2_device v4l2_dev;
	struct v4l2_subdev *v4l2_subdev;
	struct mutex lock;
	struct i2c_adapter i2c_adapter;

	u8 *buffer;
	};

	static inline struct si4713_usb_device to_si4713_dev(struct v4l2_device v4l2_dev)
	{
	return container_of(v4l2_dev, struct si4713_usb_device, v4l2_dev);
	}

	static int vidioc_querycap(struct file file, void priv,
	struct v4l2_capability *v)
	{
	struct si4713_usb_device *radio = video_drvdata(file);

	strlcpy(v->driver, "radio-usb-si4713", sizeof(v->driver));
	strlcpy(v->card, "Si4713 FM Transmitter", sizeof(v->card));
	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
	v->device_caps = V4L2_CAP_MODULATOR \| V4L2_CAP_RDS_OUTPUT;
	v->capabilities = v->device_caps \| V4L2_CAP_DEVICE_CAPS;

	return 0;
	}

	static int vidioc_g_modulator(struct file file, void priv,
	struct v4l2_modulator *vm)
	{
	struct si4713_usb_device *radio = video_drvdata(file);

	return v4l2_subdev_call(radio->v4l2_subdev, tuner, g_modulator, vm);
	}

	static int vidioc_s_modulator(struct file file, void priv,
	const struct v4l2_modulator *vm)
	{
	struct si4713_usb_device *radio = video_drvdata(file);

	return v4l2_subdev_call(radio->v4l2_subdev, tuner, s_modulator, vm);
	}

	static int vidioc_s_frequency(struct file file, void priv,
	const struct v4l2_frequency *vf)
	{
	struct si4713_usb_device *radio = video_drvdata(file);

	return v4l2_subdev_call(radio->v4l2_subdev, tuner, s_frequency, vf);
	}

	static int vidioc_g_frequency(struct file file, void priv,
	struct v4l2_frequency *vf)
	{
	struct si4713_usb_device *radio = video_drvdata(file);

	return v4l2_subdev_call(radio->v4l2_subdev, tuner, g_frequency, vf);
	}

	static const struct v4l2_ioctl_ops usb_si4713_ioctl_ops = {
	.vidioc_querycap = vidioc_querycap,
	.vidioc_g_modulator = vidioc_g_modulator,
	.vidioc_s_modulator = vidioc_s_modulator,
	.vidioc_g_frequency = vidioc_g_frequency,
	.vidioc_s_frequency = vidioc_s_frequency,
	.vidioc_log_status = v4l2_ctrl_log_status,
	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
	};

	/* File system interface */
	static const struct v4l2_file_operations usb_si4713_fops = {
	.owner = THIS_MODULE,
	.open = v4l2_fh_open,
	.release = v4l2_fh_release,
	.poll = v4l2_ctrl_poll,
	.unlocked_ioctl = video_ioctl2,
	};

	static void usb_si4713_video_device_release(struct v4l2_device *v4l2_dev)
	{
	struct si4713_usb_device *radio = to_si4713_dev(v4l2_dev);
	struct i2c_adapter *adapter = &radio->i2c_adapter;

	i2c_del_adapter(adapter);
	v4l2_device_unregister(&radio->v4l2_dev);
	kfree(radio->buffer);
	kfree(radio);
	}

	/*
	* This command sequence emulates the behaviour of the Windows driver.
	* The structure of these commands was determined by sniffing the
	* usb traffic of the device during startup.
	* Most likely, these commands make some queries to the device.
	* Commands are sent to enquire parameters like the bus mode,
	* component revision, boot mode, the device serial number etc.
	*
	* These commands are necessary to be sent in this order during startup.
	* The device fails to powerup if these commands are not sent.
	*
	* The complete list of startup commands is given in the start_seq table below.
	*/
	static int si4713_send_startup_command(struct si4713_usb_device *radio)
	{
	unsigned long until_jiffies = jiffies + usecs_to_jiffies(USB_RESP_TIMEOUT) + 1;
	u8 *buffer = radio->buffer;
	int retval;

	/* send the command */
	retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
	0x09, 0x21, 0x033f, 0, radio->buffer,
	BUFFER_LENGTH, USB_TIMEOUT);
	if (retval < 0)
	return retval;

	for (;;) {
	/* receive the response */
	retval = usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
	0x01, 0xa1, 0x033f, 0, radio->buffer,
	BUFFER_LENGTH, USB_TIMEOUT);
	if (retval < 0)
	return retval;
	if (!radio->buffer[1]) {
	/* USB traffic sniffing showed that some commands require
	* additional checks. */
	switch (buffer[1]) {
	case 0x32:
	if (radio->buffer[2] == 0)
	return 0;
	break;
	case 0x14:
	case 0x12:
	if (radio->buffer[2] & SI4713_CTS)
	return 0;
	break;
	case 0x06:
	if ((radio->buffer[2] & SI4713_CTS) && radio->buffer[9] == 0x08)
	return 0;
	break;
	default:
	return 0;
	}
	}
	if (time_is_before_jiffies(until_jiffies))
	return -EIO;
	msleep(3);
	}

	return retval;
	}

	struct si4713_start_seq_table {
	int len;
	u8 payload[8];
	};

	/*
	* Some of the startup commands that could be recognized are :
	* (0x03): Get serial number of the board (Response : CB000-00-00)
	* (0x06, 0x03, 0x03, 0x08, 0x01, 0x0f) : Get Component revision
	*/
	static struct si4713_start_seq_table start_seq[] = {

	{ 1, { 0x03 } },
	{ 2, { 0x32, 0x7f } },
	{ 6, { 0x06, 0x03, 0x03, 0x08, 0x01, 0x0f } },
	{ 2, { 0x14, 0x02 } },
	{ 2, { 0x09, 0x90 } },
	{ 3, { 0x08, 0x90, 0xfa } },
	{ 2, { 0x36, 0x01 } },
	{ 2, { 0x05, 0x03 } },
	{ 7, { 0x06, 0x00, 0x06, 0x0e, 0x01, 0x0f, 0x05 } },
	{ 1, { 0x12 } },
	/* Commands that are sent after pressing the 'Initialize'
	button in the windows application */
	{ 1, { 0x03 } },
	{ 1, { 0x01 } },
	{ 2, { 0x09, 0x90 } },
	{ 3, { 0x08, 0x90, 0xfa } },
	{ 1, { 0x34 } },
	{ 2, { 0x35, 0x01 } },
	{ 2, { 0x36, 0x01 } },
	{ 2, { 0x30, 0x09 } },
	{ 4, { 0x30, 0x06, 0x00, 0xe2 } },
	{ 3, { 0x31, 0x01, 0x30 } },
	{ 3, { 0x31, 0x04, 0x09 } },
	{ 2, { 0x05, 0x02 } },
	{ 6, { 0x06, 0x03, 0x03, 0x08, 0x01, 0x0f } },
	};

	static int si4713_start_seq(struct si4713_usb_device *radio)
	{
	int retval = 0;
	int i;

	radio->buffer[0] = 0x3f;

	for (i = 0; i < ARRAY_SIZE(start_seq); i++) {
	int len = start_seq[i].len;
	u8 *payload = start_seq[i].payload;

	memcpy(radio->buffer + 1, payload, len);
	memset(radio->buffer + len + 1, 0, BUFFER_LENGTH - 1 - len);
	retval = si4713_send_startup_command(radio);
	}

	return retval;
	}

	static struct i2c_board_info si4713_board_info = {
	I2C_BOARD_INFO("si4713", SI4713_I2C_ADDR_BUSEN_HIGH),
	};

	struct si4713_command_table {
	int command_id;
	u8 payload[8];
	};

	/*
	* Structure of a command :
	* Byte 1 : 0x3f (always)
	* Byte 2 : 0x06 (send a command)
	* Byte 3 : Unknown
	* Byte 4 : Number of arguments + 1 (for the command byte)
	* Byte 5 : Number of response bytes
	*/
	static struct si4713_command_table command_table[] = {

	{ SI4713_CMD_POWER_UP, { 0x00, SI4713_PWUP_NARGS + 1, SI4713_PWUP_NRESP} },
	{ SI4713_CMD_GET_REV, { 0x03, 0x01, SI4713_GETREV_NRESP } },
	{ SI4713_CMD_POWER_DOWN, { 0x00, 0x01, SI4713_PWDN_NRESP} },
	{ SI4713_CMD_SET_PROPERTY, { 0x00, SI4713_SET_PROP_NARGS + 1, SI4713_SET_PROP_NRESP } },
	{ SI4713_CMD_GET_PROPERTY, { 0x00, SI4713_GET_PROP_NARGS + 1, SI4713_GET_PROP_NRESP } },
	{ SI4713_CMD_TX_TUNE_FREQ, { 0x03, SI4713_TXFREQ_NARGS + 1, SI4713_TXFREQ_NRESP } },
	{ SI4713_CMD_TX_TUNE_POWER, { 0x03, SI4713_TXPWR_NARGS + 1, SI4713_TXPWR_NRESP } },
	{ SI4713_CMD_TX_TUNE_MEASURE, { 0x03, SI4713_TXMEA_NARGS + 1, SI4713_TXMEA_NRESP } },
	{ SI4713_CMD_TX_TUNE_STATUS, { 0x00, SI4713_TXSTATUS_NARGS + 1, SI4713_TXSTATUS_NRESP } },
	{ SI4713_CMD_TX_ASQ_STATUS, { 0x03, SI4713_ASQSTATUS_NARGS + 1, SI4713_ASQSTATUS_NRESP } },
	{ SI4713_CMD_GET_INT_STATUS, { 0x03, 0x01, SI4713_GET_STATUS_NRESP } },
	{ SI4713_CMD_TX_RDS_BUFF, { 0x03, SI4713_RDSBUFF_NARGS + 1, SI4713_RDSBUFF_NRESP } },
	{ SI4713_CMD_TX_RDS_PS, { 0x00, SI4713_RDSPS_NARGS + 1, SI4713_RDSPS_NRESP } },
	};

	static int send_command(struct si4713_usb_device radio, u8 payload, char *data, int len)
	{
	int retval;

	radio->buffer[0] = 0x3f;
	radio->buffer[1] = 0x06;

	memcpy(radio->buffer + 2, payload, 3);
	memcpy(radio->buffer + 5, data, len);
	memset(radio->buffer + 5 + len, 0, BUFFER_LENGTH - 5 - len);

	/* send the command */
	retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
	0x09, 0x21, 0x033f, 0, radio->buffer,
	BUFFER_LENGTH, USB_TIMEOUT);

	return retval < 0 ? retval : 0;
	}

	static int si4713_i2c_read(struct si4713_usb_device radio, char data, int len)
	{
	unsigned long until_jiffies = jiffies + usecs_to_jiffies(USB_RESP_TIMEOUT) + 1;
	int retval;

	/* receive the response */
	for (;;) {
	retval = usb_control_msg(radio->usbdev,
	usb_rcvctrlpipe(radio->usbdev, 0),
	0x01, 0xa1, 0x033f, 0, radio->buffer,
	BUFFER_LENGTH, USB_TIMEOUT);
	if (retval < 0)
	return retval;

	/*
	* Check that we get a valid reply back (buffer[1] == 0) and
	* that CTS is set before returning, otherwise we wait and try
	* again. The i2c driver also does the CTS check, but the timeouts
	* used there are much too small for this USB driver, so we wait
	* for it here.
	*/
	if (radio->buffer[1] == 0 && (radio->buffer[2] & SI4713_CTS)) {
	memcpy(data, radio->buffer + 2, len);
	return 0;
	}
	if (time_is_before_jiffies(until_jiffies)) {
	/* Zero the status value, ensuring CTS isn't set */
	data[0] = 0;
	return 0;
	}
	msleep(3);
	}
	}

	static int si4713_i2c_write(struct si4713_usb_device radio, char data, int len)
	{
	int retval = -EINVAL;
	int i;

	if (len > BUFFER_LENGTH - 5)
	return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(command_table); i++) {
	if (data[0] == command_table[i].command_id)
	retval = send_command(radio, command_table[i].payload,
	data, len);
	}

	return retval < 0 ? retval : 0;
	}

	static int si4713_transfer(struct i2c_adapter *i2c_adapter,
	struct i2c_msg *msgs, int num)
	{
	struct si4713_usb_device *radio = i2c_get_adapdata(i2c_adapter);
	int retval = -EINVAL;
	int i;

	if (num <= 0)
	return 0;

	for (i = 0; i < num; i++) {
	if (msgs[i].flags & I2C_M_RD)
	retval = si4713_i2c_read(radio, msgs[i].buf, msgs[i].len);
	else
	retval = si4713_i2c_write(radio, msgs[i].buf, msgs[i].len);
	if (retval)
	break;
	}

	return retval ? retval : num;
	}

	static u32 si4713_functionality(struct i2c_adapter *adapter)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	static struct i2c_algorithm si4713_algo = {
	.master_xfer = si4713_transfer,
	.functionality = si4713_functionality,
	};

	/* This name value shows up in the sysfs filename associated
	with this I2C adapter */
	static struct i2c_adapter si4713_i2c_adapter_template = {
	.name = "si4713-i2c",
	.owner = THIS_MODULE,
	.algo = &si4713_algo,
	};

	static int si4713_register_i2c_adapter(struct si4713_usb_device *radio)
	{
	radio->i2c_adapter = si4713_i2c_adapter_template;
	/* set up sysfs linkage to our parent device */
	radio->i2c_adapter.dev.parent = &radio->usbdev->dev;
	i2c_set_adapdata(&radio->i2c_adapter, radio);

	return i2c_add_adapter(&radio->i2c_adapter);
	}

	/* check if the device is present and register with v4l and usb if it is */
	static int usb_si4713_probe(struct usb_interface *intf,
	const struct usb_device_id *id)
	{
	struct si4713_usb_device *radio;
	struct i2c_adapter *adapter;
	struct v4l2_subdev *sd;
	int retval = -ENOMEM;

	dev_info(&intf->dev, "Si4713 development board discovered: (%04X:%04X)\n",
	id->idVendor, id->idProduct);

	/* Initialize local device structure */
	radio = kzalloc(sizeof(struct si4713_usb_device), GFP_KERNEL);
	if (radio)
	radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

	if (!radio \|\| !radio->buffer) {
	dev_err(&intf->dev, "kmalloc for si4713_usb_device failed\n");
	kfree(radio);
	return -ENOMEM;
	}

	mutex_init(&radio->lock);

	radio->usbdev = interface_to_usbdev(intf);
	radio->intf = intf;
	usb_set_intfdata(intf, &radio->v4l2_dev);

	retval = si4713_start_seq(radio);
	if (retval < 0)
	goto err_v4l2;

	retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
	if (retval < 0) {
	dev_err(&intf->dev, "couldn't register v4l2_device\n");
	goto err_v4l2;
	}

	retval = si4713_register_i2c_adapter(radio);
	if (retval < 0) {
	dev_err(&intf->dev, "could not register i2c device\n");
	goto err_i2cdev;
	}

	adapter = &radio->i2c_adapter;
	sd = v4l2_i2c_new_subdev_board(&radio->v4l2_dev, adapter,
	&si4713_board_info, NULL);
	radio->v4l2_subdev = sd;
	if (!sd) {
	dev_err(&intf->dev, "cannot get v4l2 subdevice\n");
	retval = -ENODEV;
	goto del_adapter;
	}

	radio->vdev.ctrl_handler = sd->ctrl_handler;
	radio->v4l2_dev.release = usb_si4713_video_device_release;
	strlcpy(radio->vdev.name, radio->v4l2_dev.name,
	sizeof(radio->vdev.name));
	radio->vdev.v4l2_dev = &radio->v4l2_dev;
	radio->vdev.fops = &usb_si4713_fops;
	radio->vdev.ioctl_ops = &usb_si4713_ioctl_ops;
	radio->vdev.lock = &radio->lock;
	radio->vdev.release = video_device_release_empty;
	radio->vdev.vfl_dir = VFL_DIR_TX;

	video_set_drvdata(&radio->vdev, radio);
	set_bit(V4L2_FL_USE_FH_PRIO, &radio->vdev.flags);

	retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
	if (retval < 0) {
	dev_err(&intf->dev, "could not register video device\n");
	goto del_adapter;
	}

	dev_info(&intf->dev, "V4L2 device registered as %s\n",
	video_device_node_name(&radio->vdev));

	return 0;

	del_adapter:
	i2c_del_adapter(adapter);
	err_i2cdev:
	v4l2_device_unregister(&radio->v4l2_dev);
	err_v4l2:
	kfree(radio->buffer);
	kfree(radio);
	return retval;
	}

	static void usb_si4713_disconnect(struct usb_interface *intf)
	{
	struct si4713_usb_device *radio = to_si4713_dev(usb_get_intfdata(intf));

	dev_info(&intf->dev, "Si4713 development board now disconnected\n");

	mutex_lock(&radio->lock);
	usb_set_intfdata(intf, NULL);
	video_unregister_device(&radio->vdev);
	v4l2_device_disconnect(&radio->v4l2_dev);
	mutex_unlock(&radio->lock);
	v4l2_device_put(&radio->v4l2_dev);
	}

	/* USB subsystem interface */
	static struct usb_driver usb_si4713_driver = {
	.name = "radio-usb-si4713",
	.probe = usb_si4713_probe,
	.disconnect = usb_si4713_disconnect,
	.id_table = usb_si4713_usb_device_table,
	};

	module_usb_driver(usb_si4713_driver);