drivers/media/radio/radio-keene.c - vendor/opensource/backports - Git at Google

 /*
  * Copyright (c) 2012 Hans Verkuil <hverkuil@xs4all.nl>
  *
  * 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
  */

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

 /* driver and module definitions */
 MODULE_AUTHOR("Hans Verkuil <hverkuil@xs4all.nl>");
 MODULE_DESCRIPTION("Keene FM Transmitter driver");
 MODULE_LICENSE("GPL");

 /* Actually, it advertises itself as a Logitech */
 #define USB_KEENE_VENDOR 0x046d
 #define USB_KEENE_PRODUCT 0x0a0e

 /* Probably USB_TIMEOUT should be modified in module parameter */
 #define BUFFER_LENGTH 8
 #define USB_TIMEOUT 500

 /* Frequency limits in MHz */
 #define FREQ_MIN  76U
 #define FREQ_MAX 108U
 #define FREQ_MUL 16000U

 /* USB Device ID List */
 static struct usb_device_id usb_keene_device_table[] = {
 	{USB_DEVICE_AND_INTERFACE_INFO(USB_KEENE_VENDOR, USB_KEENE_PRODUCT,
 							USB_CLASS_HID, 0, 0) },
 	{ }						/* Terminating entry */
 };

 MODULE_DEVICE_TABLE(usb, usb_keene_device_table);

 struct keene_device {
 	struct usb_device *usbdev;
 	struct usb_interface *intf;
 	struct video_device vdev;
 	struct v4l2_device v4l2_dev;
 	struct v4l2_ctrl_handler hdl;
 	struct mutex lock;

 	u8 *buffer;
 	unsigned curfreq;
 	u8 tx;
 	u8 pa;
 	bool stereo;
 	bool muted;
 	bool preemph_75_us;
 };

 static inline struct keene_device *to_keene_dev(struct v4l2_device *v4l2_dev)
 {
 	return container_of(v4l2_dev, struct keene_device, v4l2_dev);
 }

 /* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
 static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
 {
 	unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
 	int ret;

 	radio->buffer[0] = 0x00;
 	radio->buffer[1] = 0x50;
 	radio->buffer[2] = (freq_send >> 8) & 0xff;
 	radio->buffer[3] = freq_send & 0xff;
 	radio->buffer[4] = radio->pa;
 	/* If bit 4 is set, then tune to the frequency.
 	   If bit 3 is set, then unmute; if bit 2 is set, then mute.
 	   If bit 1 is set, then enter idle mode; if bit 0 is set,
 	   then enter transmit mode.
 	 */
 	radio->buffer[5] = (radio->muted ? 4 : 8) | (play ? 1 : 2) |
 							(freq ? 0x10 : 0);
 	radio->buffer[6] = 0x00;
 	radio->buffer[7] = 0x00;

 	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
 		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

 	if (ret < 0) {
 		dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
 		return ret;
 	}
 	if (freq)
 		radio->curfreq = freq;
 	return 0;
 }

 /* Set TX, stereo and preemphasis mode (50 us vs 75 us). */
 static int keene_cmd_set(struct keene_device *radio)
 {
 	int ret;

 	radio->buffer[0] = 0x00;
 	radio->buffer[1] = 0x51;
 	radio->buffer[2] = radio->tx;
 	/* If bit 0 is set, then transmit mono, otherwise stereo.
 	   If bit 2 is set, then enable 75 us preemphasis, otherwise
 	   it is 50 us. */
 	radio->buffer[3] = (radio->stereo ? 0 : 1) | (radio->preemph_75_us ? 4 : 0);
 	radio->buffer[4] = 0x00;
 	radio->buffer[5] = 0x00;
 	radio->buffer[6] = 0x00;
 	radio->buffer[7] = 0x00;

 	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
 		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

 	if (ret < 0) {
 		dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
 		return ret;
 	}
 	return 0;
 }

 /* Handle unplugging the device.
  * We call video_unregister_device in any case.
  * The last function called in this procedure is
  * usb_keene_device_release.
  */
 static void usb_keene_disconnect(struct usb_interface *intf)
 {
 	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

 	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);
 }

 static int usb_keene_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

 	return keene_cmd_main(radio, 0, false);
 }

 static int usb_keene_resume(struct usb_interface *intf)
 {
 	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

 	mdelay(50);
 	keene_cmd_set(radio);
 	keene_cmd_main(radio, radio->curfreq, true);
 	return 0;
 }

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

 	strlcpy(v->driver, "radio-keene", sizeof(v->driver));
 	strlcpy(v->card, "Keene FM Transmitter", sizeof(v->card));
 	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
 	v->device_caps = V4L2_CAP_RADIO | V4L2_CAP_MODULATOR;
 	v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;
 	return 0;
 }

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

 	if (v->index > 0)
 		return -EINVAL;

 	strlcpy(v->name, "FM", sizeof(v->name));
 	v->rangelow = FREQ_MIN * FREQ_MUL;
 	v->rangehigh = FREQ_MAX * FREQ_MUL;
 	v->txsubchans = radio->stereo ? V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
 	v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;
 	return 0;
 }

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

 	if (v->index > 0)
 		return -EINVAL;

 	radio->stereo = (v->txsubchans == V4L2_TUNER_SUB_STEREO);
 	return keene_cmd_set(radio);
 }

 static int vidioc_s_frequency(struct file *file, void *priv,
 				const struct v4l2_frequency *f)
 {
 	struct keene_device *radio = video_drvdata(file);
 	unsigned freq = f->frequency;

 	if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
 		return -EINVAL;
 	freq = clamp(freq, FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL);
 	return keene_cmd_main(radio, freq, true);
 }

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

 	if (f->tuner != 0)
 		return -EINVAL;
 	f->type = V4L2_TUNER_RADIO;
 	f->frequency = radio->curfreq;
 	return 0;
 }

 static int keene_s_ctrl(struct v4l2_ctrl *ctrl)
 {
 	static const u8 db2tx[] = {
 	     /*	 -15,  -12,   -9,   -6,   -3,    0 dB */
 		0x03, 0x13, 0x02, 0x12, 0x22, 0x32,
 	     /*	   3,    6,    9,   12,   15,   18 dB */
 		0x21, 0x31, 0x20, 0x30, 0x40, 0x50
 	};
 	struct keene_device *radio =
 		container_of(ctrl->handler, struct keene_device, hdl);

 	switch (ctrl->id) {
 	case V4L2_CID_AUDIO_MUTE:
 		radio->muted = ctrl->val;
 		return keene_cmd_main(radio, 0, true);

 	case V4L2_CID_TUNE_POWER_LEVEL:
 		/* To go from dBuV to the register value we apply the
 		   following formula: */
 		radio->pa = (ctrl->val - 71) * 100 / 62;
 		return keene_cmd_main(radio, 0, true);

 	case V4L2_CID_TUNE_PREEMPHASIS:
 		radio->preemph_75_us = ctrl->val == V4L2_PREEMPHASIS_75_uS;
 		return keene_cmd_set(radio);

 	case V4L2_CID_AUDIO_COMPRESSION_GAIN:
 		radio->tx = db2tx[(ctrl->val - (s32)ctrl->minimum) / (s32)ctrl->step];
 		return keene_cmd_set(radio);
 	}
 	return -EINVAL;
 }

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

 static const struct v4l2_ctrl_ops keene_ctrl_ops = {
 	.s_ctrl = keene_s_ctrl,
 };

 static const struct v4l2_ioctl_ops usb_keene_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,
 };

 static void usb_keene_video_device_release(struct v4l2_device *v4l2_dev)
 {
 	struct keene_device *radio = to_keene_dev(v4l2_dev);

 	/* free rest memory */
 	v4l2_ctrl_handler_free(&radio->hdl);
 	kfree(radio->buffer);
 	kfree(radio);
 }

 /* check if the device is present and register with v4l and usb if it is */
 static int usb_keene_probe(struct usb_interface *intf,
 				const struct usb_device_id *id)
 {
 	struct usb_device *dev = interface_to_usbdev(intf);
 	struct keene_device *radio;
 	struct v4l2_ctrl_handler *hdl;
 	int retval = 0;

 	/*
 	 * The Keene FM transmitter USB device has the same USB ID as
 	 * the Logitech AudioHub Speaker, but it should ignore the hid.
 	 * Check if the name is that of the Keene device.
 	 * If not, then someone connected the AudioHub and we shouldn't
 	 * attempt to handle this driver.
 	 * For reference: the product name of the AudioHub is
 	 * "AudioHub Speaker".
 	 */
 	if (dev->product && strcmp(dev->product, "B-LINK USB Audio  "))
 		return -ENODEV;

 	radio = kzalloc(sizeof(struct keene_device), GFP_KERNEL);
 	if (radio)
 		radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

 	if (!radio || !radio->buffer) {
 		dev_err(&intf->dev, "kmalloc for keene_device failed\n");
 		kfree(radio);
 		retval = -ENOMEM;
 		goto err;
 	}

 	hdl = &radio->hdl;
 	v4l2_ctrl_handler_init(hdl, 4);
 	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_MUTE,
 			0, 1, 1, 0);
 	v4l2_ctrl_new_std_menu(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_PREEMPHASIS,
 			V4L2_PREEMPHASIS_75_uS, 1, V4L2_PREEMPHASIS_50_uS);
 	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_POWER_LEVEL,
 			84, 118, 1, 118);
 	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_COMPRESSION_GAIN,
 			-15, 18, 3, 0);
 	radio->pa = 118;
 	radio->tx = 0x32;
 	radio->stereo = true;
 	if (hdl->error) {
 		retval = hdl->error;

 		v4l2_ctrl_handler_free(hdl);
 		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;
 	}

 	mutex_init(&radio->lock);

 	radio->v4l2_dev.ctrl_handler = hdl;
 	radio->v4l2_dev.release = usb_keene_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_keene_fops;
 	radio->vdev.ioctl_ops = &usb_keene_ioctl_ops;
 	radio->vdev.lock = &radio->lock;
 	radio->vdev.release = video_device_release_empty;
 	radio->vdev.vfl_dir = VFL_DIR_TX;

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

 	video_set_drvdata(&radio->vdev, radio);

 	/* at least 11ms is needed in order to settle hardware */
 	msleep(20);
 	keene_cmd_main(radio, 95.16 * FREQ_MUL, false);

 	retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
 	if (retval < 0) {
 		dev_err(&intf->dev, "could not register video device\n");
 		goto err_vdev;
 	}
 	v4l2_ctrl_handler_setup(hdl);
 	dev_info(&intf->dev, "V4L2 device registered as %s\n",
 			video_device_node_name(&radio->vdev));
 	return 0;

 err_vdev:
 	v4l2_device_unregister(&radio->v4l2_dev);
 err_v4l2:
 	kfree(radio->buffer);
 	kfree(radio);
 err:
 	return retval;
 }

 /* USB subsystem interface */
 static struct usb_driver usb_keene_driver = {
 	.name			= "radio-keene",
 	.probe			= usb_keene_probe,
 	.disconnect		= usb_keene_disconnect,
 	.id_table		= usb_keene_device_table,
 	.suspend		= usb_keene_suspend,
 	.resume			= usb_keene_resume,
 	.reset_resume		= usb_keene_resume,
 };

 module_usb_driver(usb_keene_driver);
	/*
	* Copyright (c) 2012 Hans Verkuil <hverkuil@xs4all.nl>
	*
	* 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
	*/

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

	/* driver and module definitions */
	MODULE_AUTHOR("Hans Verkuil <hverkuil@xs4all.nl>");
	MODULE_DESCRIPTION("Keene FM Transmitter driver");
	MODULE_LICENSE("GPL");

	/* Actually, it advertises itself as a Logitech */
	#define USB_KEENE_VENDOR 0x046d
	#define USB_KEENE_PRODUCT 0x0a0e

	/* Probably USB_TIMEOUT should be modified in module parameter */
	#define BUFFER_LENGTH 8
	#define USB_TIMEOUT 500

	/* Frequency limits in MHz */
	#define FREQ_MIN 76U
	#define FREQ_MAX 108U
	#define FREQ_MUL 16000U

	/* USB Device ID List */
	static struct usb_device_id usb_keene_device_table[] = {
	{USB_DEVICE_AND_INTERFACE_INFO(USB_KEENE_VENDOR, USB_KEENE_PRODUCT,
	USB_CLASS_HID, 0, 0) },
	{ } /* Terminating entry */
	};

	MODULE_DEVICE_TABLE(usb, usb_keene_device_table);

	struct keene_device {
	struct usb_device *usbdev;
	struct usb_interface *intf;
	struct video_device vdev;
	struct v4l2_device v4l2_dev;
	struct v4l2_ctrl_handler hdl;
	struct mutex lock;

	u8 *buffer;
	unsigned curfreq;
	u8 tx;
	u8 pa;
	bool stereo;
	bool muted;
	bool preemph_75_us;
	};

	static inline struct keene_device to_keene_dev(struct v4l2_device v4l2_dev)
	{
	return container_of(v4l2_dev, struct keene_device, v4l2_dev);
	}

	/* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
	static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
	{
	unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
	int ret;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x50;
	radio->buffer[2] = (freq_send >> 8) & 0xff;
	radio->buffer[3] = freq_send & 0xff;
	radio->buffer[4] = radio->pa;
	/* If bit 4 is set, then tune to the frequency.
	If bit 3 is set, then unmute; if bit 2 is set, then mute.
	If bit 1 is set, then enter idle mode; if bit 0 is set,
	then enter transmit mode.
	*/
	radio->buffer[5] = (radio->muted ? 4 : 8) \| (play ? 1 : 2) \|
	(freq ? 0x10 : 0);
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
	9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

	if (ret < 0) {
	dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
	return ret;
	}
	if (freq)
	radio->curfreq = freq;
	return 0;
	}

	/* Set TX, stereo and preemphasis mode (50 us vs 75 us). */
	static int keene_cmd_set(struct keene_device *radio)
	{
	int ret;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x51;
	radio->buffer[2] = radio->tx;
	/* If bit 0 is set, then transmit mono, otherwise stereo.
	If bit 2 is set, then enable 75 us preemphasis, otherwise
	it is 50 us. */
	radio->buffer[3] = (radio->stereo ? 0 : 1) \| (radio->preemph_75_us ? 4 : 0);
	radio->buffer[4] = 0x00;
	radio->buffer[5] = 0x00;
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
	9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

	if (ret < 0) {
	dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
	return ret;
	}
	return 0;
	}

	/* Handle unplugging the device.
	* We call video_unregister_device in any case.
	* The last function called in this procedure is
	* usb_keene_device_release.
	*/
	static void usb_keene_disconnect(struct usb_interface *intf)
	{
	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

	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);
	}

	static int usb_keene_suspend(struct usb_interface *intf, pm_message_t message)
	{
	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

	return keene_cmd_main(radio, 0, false);
	}

	static int usb_keene_resume(struct usb_interface *intf)
	{
	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

	mdelay(50);
	keene_cmd_set(radio);
	keene_cmd_main(radio, radio->curfreq, true);
	return 0;
	}

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

	strlcpy(v->driver, "radio-keene", sizeof(v->driver));
	strlcpy(v->card, "Keene FM Transmitter", sizeof(v->card));
	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
	v->device_caps = V4L2_CAP_RADIO \| V4L2_CAP_MODULATOR;
	v->capabilities = v->device_caps \| V4L2_CAP_DEVICE_CAPS;
	return 0;
	}

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

	if (v->index > 0)
	return -EINVAL;

	strlcpy(v->name, "FM", sizeof(v->name));
	v->rangelow = FREQ_MIN * FREQ_MUL;
	v->rangehigh = FREQ_MAX * FREQ_MUL;
	v->txsubchans = radio->stereo ? V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
	v->capability = V4L2_TUNER_CAP_LOW \| V4L2_TUNER_CAP_STEREO;
	return 0;
	}

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

	if (v->index > 0)
	return -EINVAL;

	radio->stereo = (v->txsubchans == V4L2_TUNER_SUB_STEREO);
	return keene_cmd_set(radio);
	}

	static int vidioc_s_frequency(struct file file, void priv,
	const struct v4l2_frequency *f)
	{
	struct keene_device *radio = video_drvdata(file);
	unsigned freq = f->frequency;

	if (f->tuner != 0 \|\| f->type != V4L2_TUNER_RADIO)
	return -EINVAL;
	freq = clamp(freq, FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL);
	return keene_cmd_main(radio, freq, true);
	}

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

	if (f->tuner != 0)
	return -EINVAL;
	f->type = V4L2_TUNER_RADIO;
	f->frequency = radio->curfreq;
	return 0;
	}

	static int keene_s_ctrl(struct v4l2_ctrl *ctrl)
	{
	static const u8 db2tx[] = {
	/* -15, -12, -9, -6, -3, 0 dB */
	0x03, 0x13, 0x02, 0x12, 0x22, 0x32,
	/* 3, 6, 9, 12, 15, 18 dB */
	0x21, 0x31, 0x20, 0x30, 0x40, 0x50
	};
	struct keene_device *radio =
	container_of(ctrl->handler, struct keene_device, hdl);

	switch (ctrl->id) {
	case V4L2_CID_AUDIO_MUTE:
	radio->muted = ctrl->val;
	return keene_cmd_main(radio, 0, true);

	case V4L2_CID_TUNE_POWER_LEVEL:
	/* To go from dBuV to the register value we apply the
	following formula: */
	radio->pa = (ctrl->val - 71) * 100 / 62;
	return keene_cmd_main(radio, 0, true);

	case V4L2_CID_TUNE_PREEMPHASIS:
	radio->preemph_75_us = ctrl->val == V4L2_PREEMPHASIS_75_uS;
	return keene_cmd_set(radio);

	case V4L2_CID_AUDIO_COMPRESSION_GAIN:
	radio->tx = db2tx[(ctrl->val - (s32)ctrl->minimum) / (s32)ctrl->step];
	return keene_cmd_set(radio);
	}
	return -EINVAL;
	}

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

	static const struct v4l2_ctrl_ops keene_ctrl_ops = {
	.s_ctrl = keene_s_ctrl,
	};

	static const struct v4l2_ioctl_ops usb_keene_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,
	};

	static void usb_keene_video_device_release(struct v4l2_device *v4l2_dev)
	{
	struct keene_device *radio = to_keene_dev(v4l2_dev);

	/* free rest memory */
	v4l2_ctrl_handler_free(&radio->hdl);
	kfree(radio->buffer);
	kfree(radio);
	}

	/* check if the device is present and register with v4l and usb if it is */
	static int usb_keene_probe(struct usb_interface *intf,
	const struct usb_device_id *id)
	{
	struct usb_device *dev = interface_to_usbdev(intf);
	struct keene_device *radio;
	struct v4l2_ctrl_handler *hdl;
	int retval = 0;

	/*
	* The Keene FM transmitter USB device has the same USB ID as
	* the Logitech AudioHub Speaker, but it should ignore the hid.
	* Check if the name is that of the Keene device.
	* If not, then someone connected the AudioHub and we shouldn't
	* attempt to handle this driver.
	* For reference: the product name of the AudioHub is
	* "AudioHub Speaker".
	*/
	if (dev->product && strcmp(dev->product, "B-LINK USB Audio "))
	return -ENODEV;

	radio = kzalloc(sizeof(struct keene_device), GFP_KERNEL);
	if (radio)
	radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

	if (!radio \|\| !radio->buffer) {
	dev_err(&intf->dev, "kmalloc for keene_device failed\n");
	kfree(radio);
	retval = -ENOMEM;
	goto err;
	}

	hdl = &radio->hdl;
	v4l2_ctrl_handler_init(hdl, 4);
	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_MUTE,
	0, 1, 1, 0);
	v4l2_ctrl_new_std_menu(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_PREEMPHASIS,
	V4L2_PREEMPHASIS_75_uS, 1, V4L2_PREEMPHASIS_50_uS);
	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_POWER_LEVEL,
	84, 118, 1, 118);
	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_COMPRESSION_GAIN,
	-15, 18, 3, 0);
	radio->pa = 118;
	radio->tx = 0x32;
	radio->stereo = true;
	if (hdl->error) {
	retval = hdl->error;

	v4l2_ctrl_handler_free(hdl);
	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;
	}

	mutex_init(&radio->lock);

	radio->v4l2_dev.ctrl_handler = hdl;
	radio->v4l2_dev.release = usb_keene_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_keene_fops;
	radio->vdev.ioctl_ops = &usb_keene_ioctl_ops;
	radio->vdev.lock = &radio->lock;
	radio->vdev.release = video_device_release_empty;
	radio->vdev.vfl_dir = VFL_DIR_TX;

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

	video_set_drvdata(&radio->vdev, radio);

	/* at least 11ms is needed in order to settle hardware */
	msleep(20);
	keene_cmd_main(radio, 95.16 * FREQ_MUL, false);

	retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
	if (retval < 0) {
	dev_err(&intf->dev, "could not register video device\n");
	goto err_vdev;
	}
	v4l2_ctrl_handler_setup(hdl);
	dev_info(&intf->dev, "V4L2 device registered as %s\n",
	video_device_node_name(&radio->vdev));
	return 0;

	err_vdev:
	v4l2_device_unregister(&radio->v4l2_dev);
	err_v4l2:
	kfree(radio->buffer);
	kfree(radio);
	err:
	return retval;
	}

	/* USB subsystem interface */
	static struct usb_driver usb_keene_driver = {
	.name = "radio-keene",
	.probe = usb_keene_probe,
	.disconnect = usb_keene_disconnect,
	.id_table = usb_keene_device_table,
	.suspend = usb_keene_suspend,
	.resume = usb_keene_resume,
	.reset_resume = usb_keene_resume,
	};

	module_usb_driver(usb_keene_driver);