/*
   * 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 <asm/uaccess.h>
  #include <asm/system.h>
  
  #include <media/v4l2-common.h>

  #include <media/v4l2-device.h>

  #include <media/v4l2-ioctl.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 *vdev = to_video_device(cd);

  	return sprintf(buf, "%i
  ", vdev->index);

  }
  
  static ssize_t show_name(struct device *cd,
  			 struct device_attribute *attr, char *buf)
  {

  	struct video_device *vdev = to_video_device(cd);

  	return sprintf(buf, "%.*s
  ", (int)sizeof(vdev->name), vdev->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(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);

  /* Device node utility functions */
  
  /* Note: these utility functions all assume that vfl_type is in the range
     [0, VFL_TYPE_MAX-1]. */
  
  #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
  /* Return the bitmap corresponding to vfl_type. */
  static inline unsigned long *devnode_bits(int vfl_type)
  {
  	/* Any types not assigned to fixed minor ranges must be mapped to
  	   one single bitmap for the purposes of finding a free node number
  	   since all those unassigned types use the same minor range. */

  	int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;

  
  	return devnode_nums[idx];
  }
  #else
  /* Return the bitmap corresponding to vfl_type. */
  static inline unsigned long *devnode_bits(int vfl_type)
  {
  	return devnode_nums[vfl_type];
  }
  #endif
  
  /* Mark device node number vdev->num as used */
  static inline void devnode_set(struct video_device *vdev)
  {
  	set_bit(vdev->num, devnode_bits(vdev->vfl_type));
  }
  
  /* Mark device node number vdev->num as unused */
  static inline void devnode_clear(struct video_device *vdev)
  {
  	clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
  }
  
  /* Try to find a free device node number in the range [from, to> */
  static inline int devnode_find(struct video_device *vdev, int from, int to)
  {
  	return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
  }

  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 *vdev)

  {

  	kfree(vdev);

  }
  EXPORT_SYMBOL(video_device_release);

  void video_device_release_empty(struct video_device *vdev)

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

  static inline void video_get(struct video_device *vdev)

  {

  	get_device(&vdev->dev);
  }
  
  static inline void video_put(struct video_device *vdev)
  {
  	put_device(&vdev->dev);
  }
  
  /* Called when the last user of the video device exits. */
  static void v4l2_device_release(struct device *cd)
  {
  	struct video_device *vdev = to_video_device(cd);

  	struct v4l2_device *v4l2_dev = vdev->v4l2_dev;

  
  	mutex_lock(&videodev_lock);

  	if (WARN_ON(video_device[vdev->minor] != vdev)) {

  		/* should not happen */

  		mutex_unlock(&videodev_lock);

  		return;
  	}

  
  	/* Free up this device for reuse */

  	video_device[vdev->minor] = NULL;

  	/* Delete the cdev on this minor as well */
  	cdev_del(vdev->cdev);
  	/* Just in case some driver tries to access this from
  	   the release() callback. */
  	vdev->cdev = NULL;

  	/* Mark device node number as free */

  	devnode_clear(vdev);

  	mutex_unlock(&videodev_lock);

  #if defined(CONFIG_MEDIA_CONTROLLER)

  	if (v4l2_dev && v4l2_dev->mdev &&

  	    vdev->vfl_type != VFL_TYPE_SUBDEV)
  		media_device_unregister_entity(&vdev->entity);
  #endif

  	/* Do not call v4l2_device_put if there is no release callback set.
  	 * Drivers that have no v4l2_device release callback might free the
  	 * v4l2_dev instance in the video_device release callback below, so we
  	 * must perform this check here.
  	 *
  	 * TODO: In the long run all drivers that use v4l2_device should use the
  	 * v4l2_device release callback. This check will then be unnecessary.
  	 */

  	if (v4l2_dev && v4l2_dev->release == NULL)

  		v4l2_dev = NULL;

  	/* Release video_device and perform other
  	   cleanups as needed. */
  	vdev->release(vdev);

  
  	/* Decrease v4l2_device refcount */
  	if (v4l2_dev)
  		v4l2_device_put(v4l2_dev);

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

  };

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

  
  /* Priority handling */
  
  static inline bool prio_is_valid(enum v4l2_priority prio)
  {
  	return prio == V4L2_PRIORITY_BACKGROUND ||
  	       prio == V4L2_PRIORITY_INTERACTIVE ||
  	       prio == V4L2_PRIORITY_RECORD;
  }
  
  void v4l2_prio_init(struct v4l2_prio_state *global)
  {
  	memset(global, 0, sizeof(*global));
  }
  EXPORT_SYMBOL(v4l2_prio_init);
  
  int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local,
  		     enum v4l2_priority new)
  {
  	if (!prio_is_valid(new))
  		return -EINVAL;
  	if (*local == new)
  		return 0;
  
  	atomic_inc(&global->prios[new]);
  	if (prio_is_valid(*local))
  		atomic_dec(&global->prios[*local]);
  	*local = new;
  	return 0;
  }
  EXPORT_SYMBOL(v4l2_prio_change);
  
  void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local)
  {
  	v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT);
  }
  EXPORT_SYMBOL(v4l2_prio_open);
  
  void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local)
  {
  	if (prio_is_valid(local))
  		atomic_dec(&global->prios[local]);
  }
  EXPORT_SYMBOL(v4l2_prio_close);
  
  enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global)
  {
  	if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0)
  		return V4L2_PRIORITY_RECORD;
  	if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0)
  		return V4L2_PRIORITY_INTERACTIVE;
  	if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0)
  		return V4L2_PRIORITY_BACKGROUND;
  	return V4L2_PRIORITY_UNSET;
  }
  EXPORT_SYMBOL(v4l2_prio_max);
  
  int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local)
  {
  	return (local < v4l2_prio_max(global)) ? -EBUSY : 0;
  }
  EXPORT_SYMBOL(v4l2_prio_check);

  static ssize_t v4l2_read(struct file *filp, char __user *buf,
  		size_t sz, loff_t *off)
  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = -ENODEV;

  
  	if (!vdev->fops->read)
  		return -EINVAL;

  	if (vdev->lock && mutex_lock_interruptible(vdev->lock))
  		return -ERESTARTSYS;

  	if (video_is_registered(vdev))
  		ret = vdev->fops->read(filp, buf, sz, off);
  	if (vdev->lock)
  		mutex_unlock(vdev->lock);
  	return ret;

  }
  
  static ssize_t v4l2_write(struct file *filp, const char __user *buf,
  		size_t sz, loff_t *off)
  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = -ENODEV;

  
  	if (!vdev->fops->write)
  		return -EINVAL;

  	if (vdev->lock && mutex_lock_interruptible(vdev->lock))
  		return -ERESTARTSYS;

  	if (video_is_registered(vdev))
  		ret = vdev->fops->write(filp, buf, sz, off);
  	if (vdev->lock)
  		mutex_unlock(vdev->lock);
  	return ret;

  }
  
  static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = POLLERR | POLLHUP;

  
  	if (!vdev->fops->poll)

  		return DEFAULT_POLLMASK;

  	if (vdev->lock)
  		mutex_lock(vdev->lock);
  	if (video_is_registered(vdev))
  		ret = vdev->fops->poll(filp, poll);
  	if (vdev->lock)
  		mutex_unlock(vdev->lock);
  	return ret;

  }

  static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = -ENODEV;

  	if (vdev->fops->unlocked_ioctl) {

  		if (vdev->lock && mutex_lock_interruptible(vdev->lock))
  			return -ERESTARTSYS;

  		if (video_is_registered(vdev))
  			ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);

  		if (vdev->lock)
  			mutex_unlock(vdev->lock);

  	} else if (vdev->fops->ioctl) {

  		/* This code path is a replacement for the BKL. It is a major
  		 * hack but it will have to do for those drivers that are not
  		 * yet converted to use unlocked_ioctl.
  		 *
  		 * There are two options: if the driver implements struct
  		 * v4l2_device, then the lock defined there is used to
  		 * serialize the ioctls. Otherwise the v4l2 core lock defined
  		 * below is used. This lock is really bad since it serializes
  		 * completely independent devices.
  		 *
  		 * Both variants suffer from the same problem: if the driver
  		 * sleeps, then it blocks all ioctls since the lock is still
  		 * held. This is very common for VIDIOC_DQBUF since that
  		 * normally waits for a frame to arrive. As a result any other
  		 * ioctl calls will proceed very, very slowly since each call
  		 * will have to wait for the VIDIOC_QBUF to finish. Things that
  		 * should take 0.01s may now take 10-20 seconds.
  		 *
  		 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
  		 * This actually works OK for videobuf-based drivers, since
  		 * videobuf will take its own internal lock.
  		 */

  		static DEFINE_MUTEX(v4l2_ioctl_mutex);

  		struct mutex *m = vdev->v4l2_dev ?
  			&vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;

  		if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
  			return -ERESTARTSYS;

  		if (video_is_registered(vdev))
  			ret = vdev->fops->ioctl(filp, cmd, arg);

  		if (cmd != VIDIOC_DQBUF)
  			mutex_unlock(m);

  	} else
  		ret = -ENOTTY;

  	return ret;

  }

  #ifdef CONFIG_MMU
  #define v4l2_get_unmapped_area NULL
  #else
  static unsigned long v4l2_get_unmapped_area(struct file *filp,
  		unsigned long addr, unsigned long len, unsigned long pgoff,
  		unsigned long flags)
  {
  	struct video_device *vdev = video_devdata(filp);
  
  	if (!vdev->fops->get_unmapped_area)
  		return -ENOSYS;
  	if (!video_is_registered(vdev))
  		return -ENODEV;
  	return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
  }
  #endif

  static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = -ENODEV;
  
  	if (!vdev->fops->mmap)
  		return ret;

  	if (vdev->lock && mutex_lock_interruptible(vdev->lock))
  		return -ERESTARTSYS;

  	if (video_is_registered(vdev))
  		ret = vdev->fops->mmap(filp, vm);
  	if (vdev->lock)
  		mutex_unlock(vdev->lock);
  	return ret;

  }
  
  /* Override for the open function */
  static int v4l2_open(struct inode *inode, struct file *filp)
  {
  	struct video_device *vdev;

  	int ret = 0;

  
  	/* Check if the video device is available */
  	mutex_lock(&videodev_lock);
  	vdev = video_devdata(filp);

  	/* return ENODEV if the video device has already been removed. */

  	if (vdev == NULL || !video_is_registered(vdev)) {

  		mutex_unlock(&videodev_lock);
  		return -ENODEV;
  	}
  	/* and increase the device refcount */
  	video_get(vdev);
  	mutex_unlock(&videodev_lock);

  	if (vdev->fops->open) {

  		if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
  			ret = -ERESTARTSYS;
  			goto err;
  		}

  		if (video_is_registered(vdev))
  			ret = vdev->fops->open(filp);
  		else
  			ret = -ENODEV;
  		if (vdev->lock)
  			mutex_unlock(vdev->lock);
  	}

  err:

  	/* decrease the refcount in case of an error */

  	if (ret)

  		video_put(vdev);
  	return ret;
  }
  
  /* Override for the release function */
  static int v4l2_release(struct inode *inode, struct file *filp)
  {
  	struct video_device *vdev = video_devdata(filp);

  	int ret = 0;

  	if (vdev->fops->release) {
  		if (vdev->lock)
  			mutex_lock(vdev->lock);

  		vdev->fops->release(filp);

  		if (vdev->lock)
  			mutex_unlock(vdev->lock);
  	}

  	/* decrease the refcount unconditionally since the release()
  	   return value is ignored. */
  	video_put(vdev);
  	return ret;
  }

  static const struct file_operations v4l2_fops = {
  	.owner = THIS_MODULE,
  	.read = v4l2_read,
  	.write = v4l2_write,
  	.open = v4l2_open,

  	.get_unmapped_area = v4l2_get_unmapped_area,

  	.mmap = v4l2_mmap,

  	.unlocked_ioctl = v4l2_ioctl,

  #ifdef CONFIG_COMPAT

  	.compat_ioctl = v4l2_compat_ioctl32,

  #endif
  	.release = v4l2_release,
  	.poll = v4l2_poll,
  	.llseek = no_llseek,
  };

  /**

   * get_index - assign stream index number based on parent device

   * @vdev: video_device to assign index number to, vdev->parent should be assigned

   *

   * Note that when this is called the new device has not yet been registered

   * in the video_device array, but it was able to obtain a minor number.

   *

   * This means that we can always obtain a free stream index number since
   * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
   * use of the video_device array.
   *
   * Returns a free index number.

   */

  static int get_index(struct video_device *vdev)

  {

  	/* This can be static since this function is called with the global
  	   videodev_lock held. */
  	static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);

  	int i;

  	/* Some drivers do not set the parent. In that case always return 0. */

  	if (vdev->parent == NULL)

  		return 0;

  
  	bitmap_zero(used, VIDEO_NUM_DEVICES);

  	for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
  		if (video_device[i] != NULL &&

  		    video_device[i]->parent == vdev->parent) {

  			set_bit(video_device[i]->index, used);

  		}
  	}

  	return find_first_zero_bit(used, VIDEO_NUM_DEVICES);

  }

  /**

   *	__video_register_device - register video4linux devices

   *	@vdev: video device structure we want to register

   *	@type: type of device to register

   *	@nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...

   *             -1 == first free)

   *	@warn_if_nr_in_use: warn if the desired device node number
   *	       was already in use and another number was chosen instead.

   *	@owner: module that owns the video device node

   *

   *	The registration code assigns minor numbers and device node numbers
   *	based on the requested type and registers the new device node with
   *	the kernel.

   *
   *	This function assumes that struct video_device was zeroed when it
   *	was allocated and does not contain any stale date.
   *

   *	An error is returned if no free minor or device node number could be
   *	found, or if the registration of the device node failed.

   *
   *	Zero is returned on success.
   *
   *	Valid types are
   *
   *	%VFL_TYPE_GRABBER - A frame grabber
   *

   *	%VFL_TYPE_VBI - Vertical blank data (undecoded)
   *
   *	%VFL_TYPE_RADIO - A radio card

   *
   *	%VFL_TYPE_SUBDEV - A subdevice

   */

  int __video_register_device(struct video_device *vdev, int type, int nr,
  		int warn_if_nr_in_use, struct module *owner)

  {
  	int i = 0;

  	int ret;

  	int minor_offset = 0;
  	int minor_cnt = VIDEO_NUM_DEVICES;
  	const char *name_base;

  	/* A minor value of -1 marks this video device as never
  	   having been registered */

  	vdev->minor = -1;

  	/* the release callback MUST be present */

  	if (WARN_ON(!vdev->release))

  		return -EINVAL;

  	/* v4l2_fh support */
  	spin_lock_init(&vdev->fh_lock);
  	INIT_LIST_HEAD(&vdev->fh_list);

  	/* Part 1: check device type */

  	switch (type) {
  	case VFL_TYPE_GRABBER:

  		name_base = "video";
  		break;

  	case VFL_TYPE_VBI:

  		name_base = "vbi";
  		break;
  	case VFL_TYPE_RADIO:

  		name_base = "radio";
  		break;

  	case VFL_TYPE_SUBDEV:
  		name_base = "v4l-subdev";
  		break;

  	default:
  		printk(KERN_ERR "%s called with unknown type: %d
  ",
  		       __func__, type);

  		return -EINVAL;

  	}

  	vdev->vfl_type = type;
  	vdev->cdev = NULL;

  	if (vdev->v4l2_dev) {
  		if (vdev->v4l2_dev->dev)
  			vdev->parent = vdev->v4l2_dev->dev;
  		if (vdev->ctrl_handler == NULL)
  			vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;

  		/* If the prio state pointer is NULL, then use the v4l2_device
  		   prio state. */
  		if (vdev->prio == NULL)

  			vdev->prio = &vdev->v4l2_dev->prio;

  	}

  	/* Part 2: find a free minor, device node number and device index. */

  #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_VBI:
  		minor_offset = 224;
  		minor_cnt = 32;
  		break;
  	default:
  		minor_offset = 128;
  		minor_cnt = 64;
  		break;
  	}
  #endif

  	/* Pick a device node number */

  	mutex_lock(&videodev_lock);

  	nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);

  	if (nr == minor_cnt)

  		nr = devnode_find(vdev, 0, minor_cnt);

  	if (nr == minor_cnt) {

  		printk(KERN_ERR "could not get a free device node number
  ");

  		mutex_unlock(&videodev_lock);
  		return -ENFILE;

  	}

  #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES

  	/* 1-on-1 mapping of device node number to minor number */

  	i = nr;
  #else

  	/* The device node number and minor numbers are independent, so
  	   we just find the first free minor number. */

  	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
  ");
  		return -ENFILE;
  	}
  #endif

  	vdev->minor = i + minor_offset;
  	vdev->num = nr;

  	devnode_set(vdev);

  	/* Should not happen since we thought this minor was free */
  	WARN_ON(video_device[vdev->minor] != NULL);

  	vdev->index = get_index(vdev);

  	mutex_unlock(&videodev_lock);

  	/* Part 3: Initialize the character device */
  	vdev->cdev = cdev_alloc();
  	if (vdev->cdev == NULL) {
  		ret = -ENOMEM;
  		goto cleanup;
  	}

  	vdev->cdev->ops = &v4l2_fops;

  	vdev->cdev->owner = owner;

  	ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);

  	if (ret < 0) {
  		printk(KERN_ERR "%s: cdev_add failed
  ", __func__);

  		kfree(vdev->cdev);
  		vdev->cdev = NULL;
  		goto cleanup;

  	}

  
  	/* Part 4: register the device with sysfs */

  	vdev->dev.class = &video_class;
  	vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
  	if (vdev->parent)
  		vdev->dev.parent = vdev->parent;

  	dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);

  	ret = device_register(&vdev->dev);

  	if (ret < 0) {
  		printk(KERN_ERR "%s: device_register failed
  ", __func__);

  		goto cleanup;

  	}

  	/* Register the release callback that will be called when the last
  	   reference to the device goes away. */
  	vdev->dev.release = v4l2_device_release;

  	if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)

  		printk(KERN_WARNING "%s: requested %s%d, got %s
  ", __func__,
  			name_base, nr, video_device_node_name(vdev));

  
  	/* Increase v4l2_device refcount */
  	if (vdev->v4l2_dev)
  		v4l2_device_get(vdev->v4l2_dev);

  #if defined(CONFIG_MEDIA_CONTROLLER)
  	/* Part 5: Register the entity. */

  	if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
  	    vdev->vfl_type != VFL_TYPE_SUBDEV) {

  		vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
  		vdev->entity.name = vdev->name;

  		vdev->entity.info.v4l.major = VIDEO_MAJOR;
  		vdev->entity.info.v4l.minor = vdev->minor;

  		ret = media_device_register_entity(vdev->v4l2_dev->mdev,
  			&vdev->entity);
  		if (ret < 0)
  			printk(KERN_WARNING
  			       "%s: media_device_register_entity failed
  ",
  			       __func__);
  	}
  #endif
  	/* Part 6: Activate this minor. The char device can now be used. */

  	set_bit(V4L2_FL_REGISTERED, &vdev->flags);

  	mutex_lock(&videodev_lock);
  	video_device[vdev->minor] = vdev;
  	mutex_unlock(&videodev_lock);

  	return 0;

  cleanup:

  	mutex_lock(&videodev_lock);

  	if (vdev->cdev)
  		cdev_del(vdev->cdev);

  	devnode_clear(vdev);

  	mutex_unlock(&videodev_lock);

  	/* Mark this video device as never having been registered. */
  	vdev->minor = -1;

  	return ret;
  }

  EXPORT_SYMBOL(__video_register_device);

  /**
   *	video_unregister_device - unregister a video4linux device

   *	@vdev: the device to unregister

   *

   *	This unregisters the passed device. Future open calls will
   *	be met with errors.

   */

  void video_unregister_device(struct video_device *vdev)

  {

  	/* Check if vdev was ever registered at all */

  	if (!vdev || !video_is_registered(vdev))

  		return;

  	mutex_lock(&videodev_lock);
  	/* This must be in a critical section to prevent a race with v4l2_open.
  	 * Once this bit has been cleared video_get may never be called again.
  	 */

  	clear_bit(V4L2_FL_REGISTERED, &vdev->flags);

  	mutex_unlock(&videodev_lock);

  	device_unregister(&vdev->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
  ");

  	ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
  	if (ret < 0) {
  		printk(KERN_WARNING "videodev: unable to get major %d
  ",
  				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
  ");
  		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");

  MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);

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