static int uvc_probe(struct usb_interface *intf,
		     const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct uvc_device *dev;
	const struct uvc_device_info *info =
		(const struct uvc_device_info *)id->driver_info;
	u32 quirks = info ? info->quirks : 0;
	...
	uvc_printk(KERN_INFO, "Found UVC %u.%02x device %s (%04x:%04x)\n",
		dev->uvc_version >> 8, dev->uvc_version & 0xff,
		udev->product ? udev->product : "<unnamed>",
		le16_to_cpu(udev->descriptor.idVendor),
		le16_to_cpu(udev->descriptor.idProduct));
	...
	/* Register video device nodes. */
	if (uvc_register_chains(dev) < 0)
		goto error;

	...
}

static int uvc_register_chains(struct uvc_device *dev)
{
	struct uvc_video_chain *chain;
	int ret;
	list_for_each_entry(chain, &dev->chains, list) {
		ret = uvc_register_terms(dev, chain);
		if (ret < 0)
			return ret;
    ...
}

/*
 * Register all video devices in all chains.
 */
static int uvc_register_terms(struct uvc_device *dev,
	struct uvc_video_chain *chain)
{
	struct uvc_streaming *stream;
	struct uvc_entity *term;
	int ret;
	list_for_each_entry(term, &chain->entities, chain) {
		if (UVC_ENTITY_TYPE(term) != UVC_TT_STREAMING)
			continue;

		stream = uvc_stream_by_id(dev, term->id);
		if (stream == NULL) {
			uvc_printk(KERN_INFO, "No streaming interface found "
				   "for terminal %u.", term->id);
			continue;
		}

		stream->chain = chain;
		ret = uvc_register_video(dev, stream);
		if (ret < 0)
			return ret;

		/* Register a metadata node, but ignore a possible failure,
		 * complete registration of video nodes anyway.
		 */
		uvc_meta_register(stream);

		term->vdev = &stream->vdev;
	}

	return 0;
}

static int uvc_register_video(struct uvc_device *dev,
		struct uvc_streaming *stream)
{
	int ret;

	/* Initialize the streaming interface with default parameters. */
	ret = uvc_video_init(stream);
	if (ret < 0) {
		uvc_printk(KERN_ERR, "Failed to initialize the device (%d).\n",
			   ret);
		return ret;
	}

	if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
		stream->chain->caps |= V4L2_CAP_VIDEO_CAPTURE
			| V4L2_CAP_META_CAPTURE;
	else
		stream->chain->caps |= V4L2_CAP_VIDEO_OUTPUT;

	uvc_debugfs_init_stream(stream);

	/* Register the device with V4L. */
	return uvc_register_video_device(dev, stream, &stream->vdev,
					 &stream->queue, stream->type,
					 &uvc_fops, &uvc_ioctl_ops);
}

int uvc_meta_register(struct uvc_streaming *stream)
{
	struct uvc_device *dev = stream->dev;
	struct video_device *vdev = &stream->meta.vdev;
	struct uvc_video_queue *queue = &stream->meta.queue;

	stream->meta.format = V4L2_META_FMT_UVC;

	/*
	 * The video interface queue uses manual locking and thus does not set
	 * the queue pointer. Set it manually here.
	 */
	vdev->queue = &queue->queue;
	return uvc_register_video_device(dev, stream, vdev, queue,
					 V4L2_BUF_TYPE_META_CAPTURE,
					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
}

int uvc_register_video_device(struct uvc_device *dev,
			      struct uvc_streaming *stream,
			      struct video_device *vdev,
			      struct uvc_video_queue *queue,
			      enum v4l2_buf_type type,
			      const struct v4l2_file_operations *fops,
			      const struct v4l2_ioctl_ops *ioctl_ops)
{
	int ret;

	/* Initialize the video buffers queue. */
	ret = uvc_queue_init(queue, type, !uvc_no_drop_param);
	if (ret)
		return ret;

	/* Register the device with V4L. */

	/*
	 * We already hold a reference to dev->udev. The video device will be
	 * unregistered before the reference is released, so we don't need to
	 * get another one.
	 */
	vdev->v4l2_dev = &dev->vdev;
	vdev->fops = fops;
	vdev->ioctl_ops = ioctl_ops;
	vdev->release = uvc_release;
	vdev->prio = &stream->chain->prio;
	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
		vdev->vfl_dir = VFL_DIR_TX;
	else
		vdev->vfl_dir = VFL_DIR_RX;

	switch (type) {
	case V4L2_BUF_TYPE_VIDEO_CAPTURE:
	default:
		vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
		break;
	case V4L2_BUF_TYPE_VIDEO_OUTPUT:
		vdev->device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
		break;
	case V4L2_BUF_TYPE_META_CAPTURE:
		vdev->device_caps = V4L2_CAP_META_CAPTURE | V4L2_CAP_STREAMING;
		break;
	}

	strlcpy(vdev->name, dev->name, sizeof vdev->name);

	/*
	 * Set the driver data before calling video_register_device, otherwise
	 * the file open() handler might race us.
	 */
	video_set_drvdata(vdev, stream);
	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
	if (ret < 0) {
		uvc_printk(KERN_ERR, "Failed to register %s device (%d).\n",
			   v4l2_type_names[type], ret);
		return ret;
	}

	kref_get(&dev->ref);
	return 0;
}

/* Register video devices. Note that if video_register_device fails,
   the release() callback of the video_device structure is *not* called, so
   the caller is responsible for freeing any data. Usually that means that
   you call video_device_release() on failure. */
static inline int __must_check video_register_device(struct video_device *vdev,
		int type, int nr)
{
	return __video_register_device(vdev, type, nr, 1, vdev->fops->owner);
}

/**
 *	__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
 *
 *	%VFL_TYPE_SDR - Software Defined Radio
 */
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;
	/* the v4l2_dev pointer MUST be present */
	if (WARN_ON(!vdev->v4l2_dev))
		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;
	case VFL_TYPE_SDR:
		/* Use device name 'swradio' because 'sdr' was already taken. */
		name_base = "swradio";
		break;
	default:
		printk(KERN_ERR "%s called with unknown type: %d\n",
		       __func__, type);
		return -EINVAL;
	}	   
	vdev->vfl_type = type;
	vdev->cdev = NULL;
	if (vdev->dev_parent == NULL)
		vdev->dev_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);
	printk(KERN_WARNING "%s vanelst nr:%d\n", __func__, nr);
	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\n");
		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\n");
		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);
	video_device[vdev->minor] = vdev;
	mutex_unlock(&videodev_lock);

	if (vdev->ioctl_ops)
		determine_valid_ioctls(vdev);

	/* 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\n", __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);
	vdev->dev.parent = vdev->dev_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\n", __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\n", __func__,
			name_base, nr, video_device_node_name(vdev));

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

#if defined(CONFIG_MEDIA_CONTROLLER)
	/* Part 5: Register the entity. */
	if (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.dev.major = VIDEO_MAJOR;
		vdev->entity.info.dev.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\n",
			       __func__);
	}
#endif
	/* Part 6: Activate this minor. The char device can now be used. */
	set_bit(V4L2_FL_REGISTERED, &vdev->flags);

	return 0;

cleanup:
	mutex_lock(&videodev_lock);
	if (vdev->cdev)
		cdev_del(vdev->cdev);
	video_device[vdev->minor] = NULL;
	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);

/* 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);
}

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;

	bitmap_zero(used, VIDEO_NUM_DEVICES);

	for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
		if (video_device[i] != NULL &&
		    video_device[i]->v4l2_dev == vdev->v4l2_dev) {
			set_bit(video_device[i]->index, used);
		}
	}

	return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
}