drivers/media/video/v4l2-dev.c - kernel/msm-4.19 - Gitiles

 /*
  * Video capture interface for Linux version 2
  *
  *	A generic video device interface for the LINUX operating system
  *	using a set of device structures/vectors for low level operations.
  *
  *	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.
  *
  * Authors:	Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
  *              Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
  *
  * Fixes:	20000516  Claudio Matsuoka <claudio@conectiva.com>
  *		- Added procfs support
  */

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kmod.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>

 #include <media/v4l2-common.h>

 #define VIDEO_NUM_DEVICES	256
 #define VIDEO_NAME              "video4linux"

 /*
  *	sysfs stuff
  */

 static ssize_t show_index(struct device *cd,
 			 struct device_attribute *attr, char *buf)
 {
 	struct video_device *vfd = container_of(cd, struct video_device, dev);

 	return sprintf(buf, "%i\n", vfd->index);
 }

 static ssize_t show_name(struct device *cd,
 			 struct device_attribute *attr, char *buf)
 {
 	struct video_device *vfd = container_of(cd, struct video_device, dev);

 	return sprintf(buf, "%.*s\n", (int)sizeof(vfd->name), vfd->name);
 }

 static struct device_attribute video_device_attrs[] = {
 	__ATTR(name, S_IRUGO, show_name, NULL),
 	__ATTR(index, S_IRUGO, show_index, NULL),
 	__ATTR_NULL
 };

 /*
  *	Active devices
  */
 static struct video_device *video_device[VIDEO_NUM_DEVICES];
 static DEFINE_MUTEX(videodev_lock);
 static DECLARE_BITMAP(video_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);

 struct video_device *video_device_alloc(void)
 {
 	return kzalloc(sizeof(struct video_device), GFP_KERNEL);
 }
 EXPORT_SYMBOL(video_device_alloc);

 void video_device_release(struct video_device *vfd)
 {
 	kfree(vfd);
 }
 EXPORT_SYMBOL(video_device_release);

 void video_device_release_empty(struct video_device *vfd)
 {
 	/* Do nothing */
 	/* Only valid when the video_device struct is a static. */
 }
 EXPORT_SYMBOL(video_device_release_empty);

 /* Called when the last user of the character device is gone. */
 static void v4l2_chardev_release(struct kobject *kobj)
 {
 	struct video_device *vfd = container_of(kobj, struct video_device, cdev.kobj);

 	mutex_lock(&videodev_lock);
 	if (video_device[vfd->minor] != vfd) {
 		mutex_unlock(&videodev_lock);
 		BUG();
 		return;
 	}

 	/* Free up this device for reuse */
 	video_device[vfd->minor] = NULL;
 	clear_bit(vfd->num, video_nums[vfd->vfl_type]);
 	mutex_unlock(&videodev_lock);

 	/* Release the character device */
 	vfd->cdev_release(kobj);
 	/* Release video_device and perform other
 	   cleanups as needed. */
 	if (vfd->release)
 		vfd->release(vfd);
 }

 /* The new kobj_type for the character device */
 static struct kobj_type v4l2_ktype_cdev_default = {
 	.release = v4l2_chardev_release,
 };

 static void video_release(struct device *cd)
 {
 	struct video_device *vfd = container_of(cd, struct video_device, dev);

 	/* It's now safe to delete the char device.
 	   This will either trigger the v4l2_chardev_release immediately (if
 	   the refcount goes to 0) or later when the last user of the
 	   character device closes it. */
 	cdev_del(&vfd->cdev);
 }

 static struct class video_class = {
 	.name = VIDEO_NAME,
 	.dev_attrs = video_device_attrs,
 	.dev_release = video_release,
 };

 struct video_device *video_devdata(struct file *file)
 {
 	return video_device[iminor(file->f_path.dentry->d_inode)];
 }
 EXPORT_SYMBOL(video_devdata);

 /**
  * get_index - assign stream number based on parent device
  * @vdev: video_device to assign index number to, vdev->dev should be assigned
  * @num: -1 if auto assign, requested number otherwise
  *
  *
  * returns -ENFILE if num is already in use, a free index number if
  * successful.
  */
 static int get_index(struct video_device *vdev, int num)
 {
 	u32 used = 0;
 	const int max_index = sizeof(used) * 8 - 1;
 	int i;

 	/* Currently a single v4l driver instance cannot create more than
 	   32 devices.
 	   Increase to u64 or an array of u32 if more are needed. */
 	if (num > max_index) {
 		printk(KERN_ERR "videodev: %s num is too large\n", __func__);
 		return -EINVAL;
 	}

 	for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 		if (video_device[i] != NULL &&
 		    video_device[i] != vdev &&
 		    video_device[i]->parent == vdev->parent) {
 			used |= 1 << video_device[i]->index;
 		}
 	}

 	if (num >= 0) {
 		if (used & (1 << num))
 			return -ENFILE;
 		return num;
 	}

 	i = ffz(used);
 	return i > max_index ? -ENFILE : i;
 }

 static const struct file_operations video_fops;

 int video_register_device(struct video_device *vfd, int type, int nr)
 {
 	return video_register_device_index(vfd, type, nr, -1);
 }
 EXPORT_SYMBOL(video_register_device);

 /**
  *	video_register_device_index - register video4linux devices
  *	@vfd:  video device structure we want to register
  *	@type: type of device to register
  *	@nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
  *             -1 == first free)
  *	@index: stream number based on parent device;
  *		-1 if auto assign, requested number otherwise
  *
  *	The registration code assigns minor numbers based on the type
  *	requested. -ENFILE is returned in all the device slots for this
  *	category are full. If not then the minor field is set and the
  *	driver initialize function is called (if non %NULL).
  *
  *	Zero is returned on success.
  *
  *	Valid types are
  *
  *	%VFL_TYPE_GRABBER - A frame grabber
  *
  *	%VFL_TYPE_VTX - A teletext device
  *
  *	%VFL_TYPE_VBI - Vertical blank data (undecoded)
  *
  *	%VFL_TYPE_RADIO - A radio card
  */

 int video_register_device_index(struct video_device *vfd, int type, int nr,
 					int index)
 {
 	int i = 0;
 	int ret;
 	int minor_offset = 0;
 	int minor_cnt = VIDEO_NUM_DEVICES;
 	const char *name_base;
 	void *priv = video_get_drvdata(vfd);

 	/* the release callback MUST be present */
 	BUG_ON(!vfd->release);

 	if (vfd == NULL)
 		return -EINVAL;

 	switch (type) {
 	case VFL_TYPE_GRABBER:
 		name_base = "video";
 		break;
 	case VFL_TYPE_VTX:
 		name_base = "vtx";
 		break;
 	case VFL_TYPE_VBI:
 		name_base = "vbi";
 		break;
 	case VFL_TYPE_RADIO:
 		name_base = "radio";
 		break;
 	default:
 		printk(KERN_ERR "%s called with unknown type: %d\n",
 		       __func__, type);
 		return -EINVAL;
 	}

 	vfd->vfl_type = type;

 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 	/* Keep the ranges for the first four types for historical
 	 * reasons.
 	 * Newer devices (not yet in place) should use the range
 	 * of 128-191 and just pick the first free minor there
 	 * (new style). */
 	switch (type) {
 	case VFL_TYPE_GRABBER:
 		minor_offset = 0;
 		minor_cnt = 64;
 		break;
 	case VFL_TYPE_RADIO:
 		minor_offset = 64;
 		minor_cnt = 64;
 		break;
 	case VFL_TYPE_VTX:
 		minor_offset = 192;
 		minor_cnt = 32;
 		break;
 	case VFL_TYPE_VBI:
 		minor_offset = 224;
 		minor_cnt = 32;
 		break;
 	default:
 		minor_offset = 128;
 		minor_cnt = 64;
 		break;
 	}
 #endif

 	/* Initialize the character device */
 	cdev_init(&vfd->cdev, vfd->fops);
 	vfd->cdev.owner = vfd->fops->owner;
 	/* pick a minor number */
 	mutex_lock(&videodev_lock);
 	nr = find_next_zero_bit(video_nums[type], minor_cnt, nr == -1 ? 0 : nr);
 	if (nr == minor_cnt)
 		nr = find_first_zero_bit(video_nums[type], minor_cnt);
 	if (nr == minor_cnt) {
 		printk(KERN_ERR "could not get a free kernel number\n");
 		mutex_unlock(&videodev_lock);
 		return -ENFILE;
 	}
 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 	/* 1-on-1 mapping of kernel number to minor number */
 	i = nr;
 #else
 	/* The kernel number and minor numbers are independent */
 	for (i = 0; i < VIDEO_NUM_DEVICES; i++)
 		if (video_device[i] == NULL)
 			break;
 	if (i == VIDEO_NUM_DEVICES) {
 		mutex_unlock(&videodev_lock);
 		printk(KERN_ERR "could not get a free minor\n");
 		return -ENFILE;
 	}
 #endif
 	vfd->minor = i + minor_offset;
 	vfd->num = nr;
 	set_bit(nr, video_nums[type]);
 	BUG_ON(video_device[vfd->minor]);
 	video_device[vfd->minor] = vfd;

 	ret = get_index(vfd, index);
 	vfd->index = ret;

 	mutex_unlock(&videodev_lock);

 	if (ret < 0) {
 		printk(KERN_ERR "%s: get_index failed\n", __func__);
 		goto fail_minor;
 	}

 	ret = cdev_add(&vfd->cdev, MKDEV(VIDEO_MAJOR, vfd->minor), 1);
 	if (ret < 0) {
 		printk(KERN_ERR "%s: cdev_add failed\n", __func__);
 		goto fail_minor;
 	}
 	/* sysfs class */
 	memset(&vfd->dev, 0, sizeof(vfd->dev));
 	/* The memset above cleared the device's drvdata, so
 	   put back the copy we made earlier. */
 	video_set_drvdata(vfd, priv);
 	vfd->dev.class = &video_class;
 	vfd->dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
 	if (vfd->parent)
 		vfd->dev.parent = vfd->parent;
 	dev_set_name(&vfd->dev, "%s%d", name_base, nr);
 	ret = device_register(&vfd->dev);
 	if (ret < 0) {
 		printk(KERN_ERR "%s: device_register failed\n", __func__);
 		goto del_cdev;
 	}
 	/* Remember the cdev's release function */
 	vfd->cdev_release = vfd->cdev.kobj.ktype->release;
 	/* Install our own */
 	vfd->cdev.kobj.ktype = &v4l2_ktype_cdev_default;
 	return 0;

 del_cdev:
 	cdev_del(&vfd->cdev);

 fail_minor:
 	mutex_lock(&videodev_lock);
 	video_device[vfd->minor] = NULL;
 	clear_bit(vfd->num, video_nums[type]);
 	mutex_unlock(&videodev_lock);
 	vfd->minor = -1;
 	return ret;
 }
 EXPORT_SYMBOL(video_register_device_index);

 /**
  *	video_unregister_device - unregister a video4linux device
  *	@vfd: the device to unregister
  *
  *	This unregisters the passed device and deassigns the minor
  *	number. Future open calls will be met with errors.
  */

 void video_unregister_device(struct video_device *vfd)
 {
 	device_unregister(&vfd->dev);
 }
 EXPORT_SYMBOL(video_unregister_device);

 /*
  *	Initialise video for linux
  */
 static int __init videodev_init(void)
 {
 	dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 	int ret;

 	printk(KERN_INFO "Linux video capture interface: v2.00\n");
 	ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 	if (ret < 0) {
 		printk(KERN_WARNING "videodev: unable to get major %d\n",
 				VIDEO_MAJOR);
 		return ret;
 	}

 	ret = class_register(&video_class);
 	if (ret < 0) {
 		unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 		printk(KERN_WARNING "video_dev: class_register failed\n");
 		return -EIO;
 	}

 	return 0;
 }

 static void __exit videodev_exit(void)
 {
 	dev_t dev = MKDEV(VIDEO_MAJOR, 0);

 	class_unregister(&video_class);
 	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 }

 module_init(videodev_init)
 module_exit(videodev_exit)

 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 MODULE_LICENSE("GPL");


 /*
  * Local variables:
  * c-basic-offset: 8
  * End:
  */
	/*
	* Video capture interface for Linux version 2
	*
	* A generic video device interface for the LINUX operating system
	* using a set of device structures/vectors for low level operations.
	*
	* 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.
	*
	* Authors: Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
	* Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
	*
	* Fixes: 20000516 Claudio Matsuoka <claudio@conectiva.com>
	* - Added procfs support
	*/

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/kmod.h>
	#include <linux/slab.h>
	#include <linux/smp_lock.h>
	#include <asm/uaccess.h>
	#include <asm/system.h>

	#include <media/v4l2-common.h>

	#define VIDEO_NUM_DEVICES 256
	#define VIDEO_NAME "video4linux"

	/*
	* sysfs stuff
	*/

	static ssize_t show_index(struct device *cd,
	struct device_attribute attr, char buf)
	{
	struct video_device *vfd = container_of(cd, struct video_device, dev);

	return sprintf(buf, "%i\n", vfd->index);
	}

	static ssize_t show_name(struct device *cd,
	struct device_attribute attr, char buf)
	{
	struct video_device *vfd = container_of(cd, struct video_device, dev);

	return sprintf(buf, "%.*s\n", (int)sizeof(vfd->name), vfd->name);
	}

	static struct device_attribute video_device_attrs[] = {
	__ATTR(name, S_IRUGO, show_name, NULL),
	__ATTR(index, S_IRUGO, show_index, NULL),
	__ATTR_NULL
	};

	/*
	* Active devices
	*/
	static struct video_device *video_device[VIDEO_NUM_DEVICES];
	static DEFINE_MUTEX(videodev_lock);
	static DECLARE_BITMAP(video_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);

	struct video_device *video_device_alloc(void)
	{
	return kzalloc(sizeof(struct video_device), GFP_KERNEL);
	}
	EXPORT_SYMBOL(video_device_alloc);

	void video_device_release(struct video_device *vfd)
	{
	kfree(vfd);
	}
	EXPORT_SYMBOL(video_device_release);

	void video_device_release_empty(struct video_device *vfd)
	{
	/* Do nothing */
	/* Only valid when the video_device struct is a static. */
	}
	EXPORT_SYMBOL(video_device_release_empty);

	/* Called when the last user of the character device is gone. */
	static void v4l2_chardev_release(struct kobject *kobj)
	{
	struct video_device *vfd = container_of(kobj, struct video_device, cdev.kobj);

	mutex_lock(&videodev_lock);
	if (video_device[vfd->minor] != vfd) {
	mutex_unlock(&videodev_lock);
	BUG();
	return;
	}

	/* Free up this device for reuse */
	video_device[vfd->minor] = NULL;
	clear_bit(vfd->num, video_nums[vfd->vfl_type]);
	mutex_unlock(&videodev_lock);

	/* Release the character device */
	vfd->cdev_release(kobj);
	/* Release video_device and perform other
	cleanups as needed. */
	if (vfd->release)
	vfd->release(vfd);
	}

	/* The new kobj_type for the character device */
	static struct kobj_type v4l2_ktype_cdev_default = {
	.release = v4l2_chardev_release,
	};

	static void video_release(struct device *cd)
	{
	struct video_device *vfd = container_of(cd, struct video_device, dev);

	/* It's now safe to delete the char device.
	This will either trigger the v4l2_chardev_release immediately (if
	the refcount goes to 0) or later when the last user of the
	character device closes it. */
	cdev_del(&vfd->cdev);
	}

	static struct class video_class = {
	.name = VIDEO_NAME,
	.dev_attrs = video_device_attrs,
	.dev_release = video_release,
	};

	struct video_device video_devdata(struct file file)
	{
	return video_device[iminor(file->f_path.dentry->d_inode)];
	}
	EXPORT_SYMBOL(video_devdata);

	/**
	* get_index - assign stream number based on parent device
	* @vdev: video_device to assign index number to, vdev->dev should be assigned
	* @num: -1 if auto assign, requested number otherwise
	*
	*
	* returns -ENFILE if num is already in use, a free index number if
	* successful.
	*/
	static int get_index(struct video_device *vdev, int num)
	{
	u32 used = 0;
	const int max_index = sizeof(used) * 8 - 1;
	int i;

	/* Currently a single v4l driver instance cannot create more than
	32 devices.
	Increase to u64 or an array of u32 if more are needed. */
	if (num > max_index) {
	printk(KERN_ERR "videodev: %s num is too large\n", __func__);
	return -EINVAL;
	}

	for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
	if (video_device[i] != NULL &&
	video_device[i] != vdev &&
	video_device[i]->parent == vdev->parent) {
	used \|= 1 << video_device[i]->index;
	}
	}

	if (num >= 0) {
	if (used & (1 << num))
	return -ENFILE;
	return num;
	}

	i = ffz(used);
	return i > max_index ? -ENFILE : i;
	}

	static const struct file_operations video_fops;

	int video_register_device(struct video_device *vfd, int type, int nr)
	{
	return video_register_device_index(vfd, type, nr, -1);
	}
	EXPORT_SYMBOL(video_register_device);

	/**
	* video_register_device_index - register video4linux devices
	* @vfd: video device structure we want to register
	* @type: type of device to register
	* @nr: which device number (0 == /dev/video0, 1 == /dev/video1, ...
	* -1 == first free)
	* @index: stream number based on parent device;
	* -1 if auto assign, requested number otherwise
	*
	* The registration code assigns minor numbers based on the type
	* requested. -ENFILE is returned in all the device slots for this
	* category are full. If not then the minor field is set and the
	* driver initialize function is called (if non %NULL).
	*
	* Zero is returned on success.
	*
	* Valid types are
	*
	* %VFL_TYPE_GRABBER - A frame grabber
	*
	* %VFL_TYPE_VTX - A teletext device
	*
	* %VFL_TYPE_VBI - Vertical blank data (undecoded)
	*
	* %VFL_TYPE_RADIO - A radio card
	*/

	int video_register_device_index(struct video_device *vfd, int type, int nr,
	int index)
	{
	int i = 0;
	int ret;
	int minor_offset = 0;
	int minor_cnt = VIDEO_NUM_DEVICES;
	const char *name_base;
	void *priv = video_get_drvdata(vfd);

	/* the release callback MUST be present */
	BUG_ON(!vfd->release);

	if (vfd == NULL)
	return -EINVAL;

	switch (type) {
	case VFL_TYPE_GRABBER:
	name_base = "video";
	break;
	case VFL_TYPE_VTX:
	name_base = "vtx";
	break;
	case VFL_TYPE_VBI:
	name_base = "vbi";
	break;
	case VFL_TYPE_RADIO:
	name_base = "radio";
	break;
	default:
	printk(KERN_ERR "%s called with unknown type: %d\n",
	__func__, type);
	return -EINVAL;
	}

	vfd->vfl_type = type;

	#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
	/* Keep the ranges for the first four types for historical
	* reasons.
	* Newer devices (not yet in place) should use the range
	* of 128-191 and just pick the first free minor there
	* (new style). */
	switch (type) {
	case VFL_TYPE_GRABBER:
	minor_offset = 0;
	minor_cnt = 64;
	break;
	case VFL_TYPE_RADIO:
	minor_offset = 64;
	minor_cnt = 64;
	break;
	case VFL_TYPE_VTX:
	minor_offset = 192;
	minor_cnt = 32;
	break;
	case VFL_TYPE_VBI:
	minor_offset = 224;
	minor_cnt = 32;
	break;
	default:
	minor_offset = 128;
	minor_cnt = 64;
	break;
	}
	#endif

	/* Initialize the character device */
	cdev_init(&vfd->cdev, vfd->fops);
	vfd->cdev.owner = vfd->fops->owner;
	/* pick a minor number */
	mutex_lock(&videodev_lock);
	nr = find_next_zero_bit(video_nums[type], minor_cnt, nr == -1 ? 0 : nr);
	if (nr == minor_cnt)
	nr = find_first_zero_bit(video_nums[type], minor_cnt);
	if (nr == minor_cnt) {
	printk(KERN_ERR "could not get a free kernel number\n");
	mutex_unlock(&videodev_lock);
	return -ENFILE;
	}
	#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
	/* 1-on-1 mapping of kernel number to minor number */
	i = nr;
	#else
	/* The kernel number and minor numbers are independent */
	for (i = 0; i < VIDEO_NUM_DEVICES; i++)
	if (video_device[i] == NULL)
	break;
	if (i == VIDEO_NUM_DEVICES) {
	mutex_unlock(&videodev_lock);
	printk(KERN_ERR "could not get a free minor\n");
	return -ENFILE;
	}
	#endif
	vfd->minor = i + minor_offset;
	vfd->num = nr;
	set_bit(nr, video_nums[type]);
	BUG_ON(video_device[vfd->minor]);
	video_device[vfd->minor] = vfd;

	ret = get_index(vfd, index);
	vfd->index = ret;

	mutex_unlock(&videodev_lock);

	if (ret < 0) {
	printk(KERN_ERR "%s: get_index failed\n", __func__);
	goto fail_minor;
	}

	ret = cdev_add(&vfd->cdev, MKDEV(VIDEO_MAJOR, vfd->minor), 1);
	if (ret < 0) {
	printk(KERN_ERR "%s: cdev_add failed\n", __func__);
	goto fail_minor;
	}
	/* sysfs class */
	memset(&vfd->dev, 0, sizeof(vfd->dev));
	/* The memset above cleared the device's drvdata, so
	put back the copy we made earlier. */
	video_set_drvdata(vfd, priv);
	vfd->dev.class = &video_class;
	vfd->dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
	if (vfd->parent)
	vfd->dev.parent = vfd->parent;
	dev_set_name(&vfd->dev, "%s%d", name_base, nr);
	ret = device_register(&vfd->dev);
	if (ret < 0) {
	printk(KERN_ERR "%s: device_register failed\n", __func__);
	goto del_cdev;
	}
	/* Remember the cdev's release function */
	vfd->cdev_release = vfd->cdev.kobj.ktype->release;
	/* Install our own */
	vfd->cdev.kobj.ktype = &v4l2_ktype_cdev_default;
	return 0;

	del_cdev:
	cdev_del(&vfd->cdev);

	fail_minor:
	mutex_lock(&videodev_lock);
	video_device[vfd->minor] = NULL;
	clear_bit(vfd->num, video_nums[type]);
	mutex_unlock(&videodev_lock);
	vfd->minor = -1;
	return ret;
	}
	EXPORT_SYMBOL(video_register_device_index);

	/**
	* video_unregister_device - unregister a video4linux device
	* @vfd: the device to unregister
	*
	* This unregisters the passed device and deassigns the minor
	* number. Future open calls will be met with errors.
	*/

	void video_unregister_device(struct video_device *vfd)
	{
	device_unregister(&vfd->dev);
	}
	EXPORT_SYMBOL(video_unregister_device);

	/*
	* Initialise video for linux
	*/
	static int __init videodev_init(void)
	{
	dev_t dev = MKDEV(VIDEO_MAJOR, 0);
	int ret;

	printk(KERN_INFO "Linux video capture interface: v2.00\n");
	ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
	if (ret < 0) {
	printk(KERN_WARNING "videodev: unable to get major %d\n",
	VIDEO_MAJOR);
	return ret;
	}

	ret = class_register(&video_class);
	if (ret < 0) {
	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
	printk(KERN_WARNING "video_dev: class_register failed\n");
	return -EIO;
	}

	return 0;
	}

	static void __exit videodev_exit(void)
	{
	dev_t dev = MKDEV(VIDEO_MAJOR, 0);

	class_unregister(&video_class);
	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
	}

	module_init(videodev_init)
	module_exit(videodev_exit)

	MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
	MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
	MODULE_LICENSE("GPL");


	/*
	* Local variables:
	* c-basic-offset: 8
	* End:
	*/