drivers/media/v4l2-core/v4l2-dev.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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.
 *
 * Authors:	Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
 *              Mauro Carvalho Chehab <mchehab@kernel.org> (version 2)
 *
 * Fixes:	20000516  Claudio Matsuoka <claudio@conectiva.com>
 *		- Added procfs support
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/debugfs.h>
#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/uaccess.h>

#include <media/v4l2-common.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-event.h>

#define VIDEO_NUM_DEVICES	256
#define VIDEO_NAME              "video4linux"

#define dprintk(fmt, arg...) do {					\
		printk(KERN_DEBUG pr_fmt("%s: " fmt),			\
		       __func__, ##arg);				\
} while (0)

/*
 *	sysfs stuff
 */

static ssize_t index_show(struct device *cd,
			  struct device_attribute *attr, char *buf)
{
	struct video_device *vdev = to_video_device(cd);

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

static ssize_t dev_debug_show(struct device *cd,
			  struct device_attribute *attr, char *buf)
{
	struct video_device *vdev = to_video_device(cd);

	return sprintf(buf, "%i\n", vdev->dev_debug);
}

static ssize_t dev_debug_store(struct device *cd, struct device_attribute *attr,
			  const char *buf, size_t len)
{
	struct video_device *vdev = to_video_device(cd);
	int res = 0;
	u16 value;

	res = kstrtou16(buf, 0, &value);
	if (res)
		return res;

	vdev->dev_debug = value;
	return len;
}
static DEVICE_ATTR_RW(dev_debug);

static ssize_t name_show(struct device *cd,
			 struct device_attribute *attr, char *buf)
{
	struct video_device *vdev = to_video_device(cd);

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

static struct attribute *video_device_attrs[] = {
	&dev_attr_name.attr,
	&dev_attr_dev_debug.attr,
	&dev_attr_index.attr,
	NULL,
};
ATTRIBUTE_GROUPS(video_device);

/*
 *	Active devices
 */
static struct video_device *video_devices[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(enum vfl_devnode_type 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(enum vfl_devnode_type 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_devices[vdev->minor] != vdev)) {
		/* should not happen */
		mutex_unlock(&videodev_lock);
		return;
	}

	/* Free up this device for reuse */
	video_devices[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->mdev && vdev->vfl_dir != VFL_DIR_M2M) {
		/* Remove interfaces and interface links */
		media_devnode_remove(vdev->intf_devnode);
		if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN)
			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->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_groups = video_device_groups,
};

struct video_device *video_devdata(struct file *file)
{
	return video_devices[iminor(file_inode(file))];
}
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 (video_is_registered(vdev))
		ret = vdev->fops->read(filp, buf, sz, off);
	if ((vdev->dev_debug & V4L2_DEV_DEBUG_FOP) &&
	    (vdev->dev_debug & V4L2_DEV_DEBUG_STREAMING))
		dprintk("%s: read: %zd (%d)\n",
			video_device_node_name(vdev), sz, ret);
	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 (video_is_registered(vdev))
		ret = vdev->fops->write(filp, buf, sz, off);
	if ((vdev->dev_debug & V4L2_DEV_DEBUG_FOP) &&
	    (vdev->dev_debug & V4L2_DEV_DEBUG_STREAMING))
		dprintk("%s: write: %zd (%d)\n",
			video_device_node_name(vdev), sz, ret);
	return ret;
}

static __poll_t v4l2_poll(struct file *filp, struct poll_table_struct *poll)
{
	struct video_device *vdev = video_devdata(filp);
	__poll_t res = EPOLLERR | EPOLLHUP | EPOLLPRI;

	if (video_is_registered(vdev)) {
		if (!vdev->fops->poll)
			res = DEFAULT_POLLMASK;
		else
			res = vdev->fops->poll(filp, poll);
	}
	if (vdev->dev_debug & V4L2_DEV_DEBUG_POLL)
		dprintk("%s: poll: %08x %08x\n",
			video_device_node_name(vdev), res,
			poll_requested_events(poll));
	return res;
}

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

	if (!vdev->fops->get_unmapped_area)
		return -ENOSYS;
	if (!video_is_registered(vdev))
		return -ENODEV;
	ret = vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
	if (vdev->dev_debug & V4L2_DEV_DEBUG_FOP)
		dprintk("%s: get_unmapped_area (%d)\n",
			video_device_node_name(vdev), ret);
	return ret;
}
#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 -ENODEV;
	if (video_is_registered(vdev))
		ret = vdev->fops->mmap(filp, vm);
	if (vdev->dev_debug & V4L2_DEV_DEBUG_FOP)
		dprintk("%s: mmap (%d)\n",
			video_device_node_name(vdev), ret);
	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 (video_is_registered(vdev))
			ret = vdev->fops->open(filp);
		else
			ret = -ENODEV;
	}

	if (vdev->dev_debug & V4L2_DEV_DEBUG_FOP)
		dprintk("%s: open (%d)\n",
			video_device_node_name(vdev), ret);
	/* 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;

	/*
	 * We need to serialize the release() with queueing new requests.
	 * The release() may trigger the cancellation of a streaming
	 * operation, and that should not be mixed with queueing a new
	 * request at the same time.
	 */
	if (vdev->fops->release) {
		if (v4l2_device_supports_requests(vdev->v4l2_dev)) {
			mutex_lock(&vdev->v4l2_dev->mdev->req_queue_mutex);
			ret = vdev->fops->release(filp);
			mutex_unlock(&vdev->v4l2_dev->mdev->req_queue_mutex);
		} else {
			ret = vdev->fops->release(filp);
		}
	}

	if (vdev->dev_debug & V4L2_DEV_DEBUG_FOP)
		dprintk("%s: release\n",
			video_device_node_name(vdev));

	/* 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 v4l2_dev
 * @vdev: video_device to assign index number to, vdev->v4l2_dev 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;

	bitmap_zero(used, VIDEO_NUM_DEVICES);

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

	return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
}

#define SET_VALID_IOCTL(ops, cmd, op) \
	do { if ((ops)->op) __set_bit(_IOC_NR(cmd), valid_ioctls); } while (0)

/* This determines which ioctls are actually implemented in the driver.
   It's a one-time thing which simplifies video_ioctl2 as it can just do
   a bit test.

   Note that drivers can override this by setting bits to 1 in
   vdev->valid_ioctls. If an ioctl is marked as 1 when this function is
   called, then that ioctl will actually be marked as unimplemented.

   It does that by first setting up the local valid_ioctls bitmap, and
   at the end do a:

   vdev->valid_ioctls = valid_ioctls & ~(vdev->valid_ioctls)
 */
static void determine_valid_ioctls(struct video_device *vdev)
{
	const u32 vid_caps = V4L2_CAP_VIDEO_CAPTURE |
			     V4L2_CAP_VIDEO_CAPTURE_MPLANE |
			     V4L2_CAP_VIDEO_OUTPUT |
			     V4L2_CAP_VIDEO_OUTPUT_MPLANE |
			     V4L2_CAP_VIDEO_M2M | V4L2_CAP_VIDEO_M2M_MPLANE;
	const u32 meta_caps = V4L2_CAP_META_CAPTURE |
			      V4L2_CAP_META_OUTPUT;
	DECLARE_BITMAP(valid_ioctls, BASE_VIDIOC_PRIVATE);
	const struct v4l2_ioctl_ops *ops = vdev->ioctl_ops;
	bool is_vid = vdev->vfl_type == VFL_TYPE_VIDEO &&
		      (vdev->device_caps & vid_caps);
	bool is_vbi = vdev->vfl_type == VFL_TYPE_VBI;
	bool is_radio = vdev->vfl_type == VFL_TYPE_RADIO;
	bool is_sdr = vdev->vfl_type == VFL_TYPE_SDR;
	bool is_tch = vdev->vfl_type == VFL_TYPE_TOUCH;
	bool is_meta = vdev->vfl_type == VFL_TYPE_VIDEO &&
		       (vdev->device_caps & meta_caps);
	bool is_rx = vdev->vfl_dir != VFL_DIR_TX;
	bool is_tx = vdev->vfl_dir != VFL_DIR_RX;
	bool is_io_mc = vdev->device_caps & V4L2_CAP_IO_MC;

	bitmap_zero(valid_ioctls, BASE_VIDIOC_PRIVATE);

	/* vfl_type and vfl_dir independent ioctls */

	SET_VALID_IOCTL(ops, VIDIOC_QUERYCAP, vidioc_querycap);
	__set_bit(_IOC_NR(VIDIOC_G_PRIORITY), valid_ioctls);
	__set_bit(_IOC_NR(VIDIOC_S_PRIORITY), valid_ioctls);

	/* Note: the control handler can also be passed through the filehandle,
	   and that can't be tested here. If the bit for these control ioctls
	   is set, then the ioctl is valid. But if it is 0, then it can still
	   be valid if the filehandle passed the control handler. */
	if (vdev->ctrl_handler || ops->vidioc_queryctrl)
		__set_bit(_IOC_NR(VIDIOC_QUERYCTRL), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_query_ext_ctrl)
		__set_bit(_IOC_NR(VIDIOC_QUERY_EXT_CTRL), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_g_ctrl || ops->vidioc_g_ext_ctrls)
		__set_bit(_IOC_NR(VIDIOC_G_CTRL), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_s_ctrl || ops->vidioc_s_ext_ctrls)
		__set_bit(_IOC_NR(VIDIOC_S_CTRL), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_g_ext_ctrls)
		__set_bit(_IOC_NR(VIDIOC_G_EXT_CTRLS), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_s_ext_ctrls)
		__set_bit(_IOC_NR(VIDIOC_S_EXT_CTRLS), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_try_ext_ctrls)
		__set_bit(_IOC_NR(VIDIOC_TRY_EXT_CTRLS), valid_ioctls);
	if (vdev->ctrl_handler || ops->vidioc_querymenu)
		__set_bit(_IOC_NR(VIDIOC_QUERYMENU), valid_ioctls);
	if (!is_tch) {
		SET_VALID_IOCTL(ops, VIDIOC_G_FREQUENCY, vidioc_g_frequency);
		SET_VALID_IOCTL(ops, VIDIOC_S_FREQUENCY, vidioc_s_frequency);
	}
	SET_VALID_IOCTL(ops, VIDIOC_LOG_STATUS, vidioc_log_status);
#ifdef CONFIG_VIDEO_ADV_DEBUG
	__set_bit(_IOC_NR(VIDIOC_DBG_G_CHIP_INFO), valid_ioctls);
	__set_bit(_IOC_NR(VIDIOC_DBG_G_REGISTER), valid_ioctls);
	__set_bit(_IOC_NR(VIDIOC_DBG_S_REGISTER), valid_ioctls);
#endif
	/* yes, really vidioc_subscribe_event */
	SET_VALID_IOCTL(ops, VIDIOC_DQEVENT, vidioc_subscribe_event);
	SET_VALID_IOCTL(ops, VIDIOC_SUBSCRIBE_EVENT, vidioc_subscribe_event);
	SET_VALID_IOCTL(ops, VIDIOC_UNSUBSCRIBE_EVENT, vidioc_unsubscribe_event);
	if (ops->vidioc_enum_freq_bands || ops->vidioc_g_tuner || ops->vidioc_g_modulator)
		__set_bit(_IOC_NR(VIDIOC_ENUM_FREQ_BANDS), valid_ioctls);

	if (is_vid) {
		/* video specific ioctls */
		if ((is_rx && (ops->vidioc_enum_fmt_vid_cap ||
			       ops->vidioc_enum_fmt_vid_overlay)) ||
		    (is_tx && ops->vidioc_enum_fmt_vid_out))
			__set_bit(_IOC_NR(VIDIOC_ENUM_FMT), valid_ioctls);
		if ((is_rx && (ops->vidioc_g_fmt_vid_cap ||
			       ops->vidioc_g_fmt_vid_cap_mplane ||
			       ops->vidioc_g_fmt_vid_overlay)) ||
		    (is_tx && (ops->vidioc_g_fmt_vid_out ||
			       ops->vidioc_g_fmt_vid_out_mplane ||
			       ops->vidioc_g_fmt_vid_out_overlay)))
			__set_bit(_IOC_NR(VIDIOC_G_FMT), valid_ioctls);
		if ((is_rx && (ops->vidioc_s_fmt_vid_cap ||
			       ops->vidioc_s_fmt_vid_cap_mplane ||
			       ops->vidioc_s_fmt_vid_overlay)) ||
		    (is_tx && (ops->vidioc_s_fmt_vid_out ||
			       ops->vidioc_s_fmt_vid_out_mplane ||
			       ops->vidioc_s_fmt_vid_out_overlay)))
			__set_bit(_IOC_NR(VIDIOC_S_FMT), valid_ioctls);
		if ((is_rx && (ops->vidioc_try_fmt_vid_cap ||
			       ops->vidioc_try_fmt_vid_cap_mplane ||
			       ops->vidioc_try_fmt_vid_overlay)) ||
		    (is_tx && (ops->vidioc_try_fmt_vid_out ||
			       ops->vidioc_try_fmt_vid_out_mplane ||
			       ops->vidioc_try_fmt_vid_out_overlay)))
			__set_bit(_IOC_NR(VIDIOC_TRY_FMT), valid_ioctls);
		SET_VALID_IOCTL(ops, VIDIOC_OVERLAY, vidioc_overlay);
		SET_VALID_IOCTL(ops, VIDIOC_G_FBUF, vidioc_g_fbuf);
		SET_VALID_IOCTL(ops, VIDIOC_S_FBUF, vidioc_s_fbuf);
		SET_VALID_IOCTL(ops, VIDIOC_G_JPEGCOMP, vidioc_g_jpegcomp);
		SET_VALID_IOCTL(ops, VIDIOC_S_JPEGCOMP, vidioc_s_jpegcomp);
		SET_VALID_IOCTL(ops, VIDIOC_G_ENC_INDEX, vidioc_g_enc_index);
		SET_VALID_IOCTL(ops, VIDIOC_ENCODER_CMD, vidioc_encoder_cmd);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_ENCODER_CMD, vidioc_try_encoder_cmd);
		SET_VALID_IOCTL(ops, VIDIOC_DECODER_CMD, vidioc_decoder_cmd);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_DECODER_CMD, vidioc_try_decoder_cmd);
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMESIZES, vidioc_enum_framesizes);
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMEINTERVALS, vidioc_enum_frameintervals);
		if (ops->vidioc_g_selection) {
			__set_bit(_IOC_NR(VIDIOC_G_CROP), valid_ioctls);
			__set_bit(_IOC_NR(VIDIOC_CROPCAP), valid_ioctls);
		}
		if (ops->vidioc_s_selection)
			__set_bit(_IOC_NR(VIDIOC_S_CROP), valid_ioctls);
		SET_VALID_IOCTL(ops, VIDIOC_G_SELECTION, vidioc_g_selection);
		SET_VALID_IOCTL(ops, VIDIOC_S_SELECTION, vidioc_s_selection);
	}
	if (is_meta && is_rx) {
		/* metadata capture specific ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_meta_cap);
		SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_meta_cap);
		SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_meta_cap);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_meta_cap);
	} else if (is_meta && is_tx) {
		/* metadata output specific ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_meta_out);
		SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_meta_out);
		SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_meta_out);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_meta_out);
	}
	if (is_vbi) {
		/* vbi specific ioctls */
		if ((is_rx && (ops->vidioc_g_fmt_vbi_cap ||
			       ops->vidioc_g_fmt_sliced_vbi_cap)) ||
		    (is_tx && (ops->vidioc_g_fmt_vbi_out ||
			       ops->vidioc_g_fmt_sliced_vbi_out)))
			__set_bit(_IOC_NR(VIDIOC_G_FMT), valid_ioctls);
		if ((is_rx && (ops->vidioc_s_fmt_vbi_cap ||
			       ops->vidioc_s_fmt_sliced_vbi_cap)) ||
		    (is_tx && (ops->vidioc_s_fmt_vbi_out ||
			       ops->vidioc_s_fmt_sliced_vbi_out)))
			__set_bit(_IOC_NR(VIDIOC_S_FMT), valid_ioctls);
		if ((is_rx && (ops->vidioc_try_fmt_vbi_cap ||
			       ops->vidioc_try_fmt_sliced_vbi_cap)) ||
		    (is_tx && (ops->vidioc_try_fmt_vbi_out ||
			       ops->vidioc_try_fmt_sliced_vbi_out)))
			__set_bit(_IOC_NR(VIDIOC_TRY_FMT), valid_ioctls);
		SET_VALID_IOCTL(ops, VIDIOC_G_SLICED_VBI_CAP, vidioc_g_sliced_vbi_cap);
	} else if (is_tch) {
		/* touch specific ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_vid_cap);
		SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_vid_cap);
		SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_vid_cap);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_vid_cap);
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMESIZES, vidioc_enum_framesizes);
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMEINTERVALS, vidioc_enum_frameintervals);
		SET_VALID_IOCTL(ops, VIDIOC_ENUMINPUT, vidioc_enum_input);
		SET_VALID_IOCTL(ops, VIDIOC_G_INPUT, vidioc_g_input);
		SET_VALID_IOCTL(ops, VIDIOC_S_INPUT, vidioc_s_input);
		SET_VALID_IOCTL(ops, VIDIOC_G_PARM, vidioc_g_parm);
		SET_VALID_IOCTL(ops, VIDIOC_S_PARM, vidioc_s_parm);
	} else if (is_sdr && is_rx) {
		/* SDR receiver specific ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_sdr_cap);
		SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_sdr_cap);
		SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_sdr_cap);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_sdr_cap);
	} else if (is_sdr && is_tx) {
		/* SDR transmitter specific ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_sdr_out);
		SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_sdr_out);
		SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_sdr_out);
		SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_sdr_out);
	}

	if (is_vid || is_vbi || is_sdr || is_tch || is_meta) {
		/* ioctls valid for video, vbi, sdr, touch and metadata */
		SET_VALID_IOCTL(ops, VIDIOC_REQBUFS, vidioc_reqbufs);
		SET_VALID_IOCTL(ops, VIDIOC_QUERYBUF, vidioc_querybuf);
		SET_VALID_IOCTL(ops, VIDIOC_QBUF, vidioc_qbuf);
		SET_VALID_IOCTL(ops, VIDIOC_EXPBUF, vidioc_expbuf);
		SET_VALID_IOCTL(ops, VIDIOC_DQBUF, vidioc_dqbuf);
		SET_VALID_IOCTL(ops, VIDIOC_CREATE_BUFS, vidioc_create_bufs);
		SET_VALID_IOCTL(ops, VIDIOC_PREPARE_BUF, vidioc_prepare_buf);
		SET_VALID_IOCTL(ops, VIDIOC_STREAMON, vidioc_streamon);
		SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff);
	}

	if (is_vid || is_vbi || is_meta) {
		/* ioctls valid for video, vbi and metadata */
		if (ops->vidioc_s_std)
			__set_bit(_IOC_NR(VIDIOC_ENUMSTD), valid_ioctls);
		SET_VALID_IOCTL(ops, VIDIOC_S_STD, vidioc_s_std);
		SET_VALID_IOCTL(ops, VIDIOC_G_STD, vidioc_g_std);
		if (is_rx) {
			SET_VALID_IOCTL(ops, VIDIOC_QUERYSTD, vidioc_querystd);
			if (is_io_mc) {
				__set_bit(_IOC_NR(VIDIOC_ENUMINPUT), valid_ioctls);
				__set_bit(_IOC_NR(VIDIOC_G_INPUT), valid_ioctls);
				__set_bit(_IOC_NR(VIDIOC_S_INPUT), valid_ioctls);
			} else {
				SET_VALID_IOCTL(ops, VIDIOC_ENUMINPUT, vidioc_enum_input);
				SET_VALID_IOCTL(ops, VIDIOC_G_INPUT, vidioc_g_input);
				SET_VALID_IOCTL(ops, VIDIOC_S_INPUT, vidioc_s_input);
			}
			SET_VALID_IOCTL(ops, VIDIOC_ENUMAUDIO, vidioc_enumaudio);
			SET_VALID_IOCTL(ops, VIDIOC_G_AUDIO, vidioc_g_audio);
			SET_VALID_IOCTL(ops, VIDIOC_S_AUDIO, vidioc_s_audio);
			SET_VALID_IOCTL(ops, VIDIOC_QUERY_DV_TIMINGS, vidioc_query_dv_timings);
			SET_VALID_IOCTL(ops, VIDIOC_S_EDID, vidioc_s_edid);
		}
		if (is_tx) {
			if (is_io_mc) {
				__set_bit(_IOC_NR(VIDIOC_ENUMOUTPUT), valid_ioctls);
				__set_bit(_IOC_NR(VIDIOC_G_OUTPUT), valid_ioctls);
				__set_bit(_IOC_NR(VIDIOC_S_OUTPUT), valid_ioctls);
			} else {
				SET_VALID_IOCTL(ops, VIDIOC_ENUMOUTPUT, vidioc_enum_output);
				SET_VALID_IOCTL(ops, VIDIOC_G_OUTPUT, vidioc_g_output);
				SET_VALID_IOCTL(ops, VIDIOC_S_OUTPUT, vidioc_s_output);
			}
			SET_VALID_IOCTL(ops, VIDIOC_ENUMAUDOUT, vidioc_enumaudout);
			SET_VALID_IOCTL(ops, VIDIOC_G_AUDOUT, vidioc_g_audout);
			SET_VALID_IOCTL(ops, VIDIOC_S_AUDOUT, vidioc_s_audout);
		}
		if (ops->vidioc_g_parm || ops->vidioc_g_std)
			__set_bit(_IOC_NR(VIDIOC_G_PARM), valid_ioctls);
		SET_VALID_IOCTL(ops, VIDIOC_S_PARM, vidioc_s_parm);
		SET_VALID_IOCTL(ops, VIDIOC_S_DV_TIMINGS, vidioc_s_dv_timings);
		SET_VALID_IOCTL(ops, VIDIOC_G_DV_TIMINGS, vidioc_g_dv_timings);
		SET_VALID_IOCTL(ops, VIDIOC_ENUM_DV_TIMINGS, vidioc_enum_dv_timings);
		SET_VALID_IOCTL(ops, VIDIOC_DV_TIMINGS_CAP, vidioc_dv_timings_cap);
		SET_VALID_IOCTL(ops, VIDIOC_G_EDID, vidioc_g_edid);
	}
	if (is_tx && (is_radio || is_sdr)) {
		/* radio transmitter only ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_G_MODULATOR, vidioc_g_modulator);
		SET_VALID_IOCTL(ops, VIDIOC_S_MODULATOR, vidioc_s_modulator);
	}
	if (is_rx && !is_tch) {
		/* receiver only ioctls */
		SET_VALID_IOCTL(ops, VIDIOC_G_TUNER, vidioc_g_tuner);
		SET_VALID_IOCTL(ops, VIDIOC_S_TUNER, vidioc_s_tuner);
		SET_VALID_IOCTL(ops, VIDIOC_S_HW_FREQ_SEEK, vidioc_s_hw_freq_seek);
	}

	bitmap_andnot(vdev->valid_ioctls, valid_ioctls, vdev->valid_ioctls,
			BASE_VIDIOC_PRIVATE);
}

static int video_register_media_controller(struct video_device *vdev)
{
#if defined(CONFIG_MEDIA_CONTROLLER)
	u32 intf_type;
	int ret;

	/* Memory-to-memory devices are more complex and use
	 * their own function to register its mc entities.
	 */
	if (!vdev->v4l2_dev->mdev || vdev->vfl_dir == VFL_DIR_M2M)
		return 0;

	vdev->entity.obj_type = MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
	vdev->entity.function = MEDIA_ENT_F_UNKNOWN;

	switch (vdev->vfl_type) {
	case VFL_TYPE_VIDEO:
		intf_type = MEDIA_INTF_T_V4L_VIDEO;
		vdev->entity.function = MEDIA_ENT_F_IO_V4L;
		break;
	case VFL_TYPE_VBI:
		intf_type = MEDIA_INTF_T_V4L_VBI;
		vdev->entity.function = MEDIA_ENT_F_IO_VBI;
		break;
	case VFL_TYPE_SDR:
		intf_type = MEDIA_INTF_T_V4L_SWRADIO;
		vdev->entity.function = MEDIA_ENT_F_IO_SWRADIO;
		break;
	case VFL_TYPE_TOUCH:
		intf_type = MEDIA_INTF_T_V4L_TOUCH;
		vdev->entity.function = MEDIA_ENT_F_IO_V4L;
		break;
	case VFL_TYPE_RADIO:
		intf_type = MEDIA_INTF_T_V4L_RADIO;
		/*
		 * Radio doesn't have an entity at the V4L2 side to represent
		 * radio input or output. Instead, the audio input/output goes
		 * via either physical wires or ALSA.
		 */
		break;
	case VFL_TYPE_SUBDEV:
		intf_type = MEDIA_INTF_T_V4L_SUBDEV;
		/* Entity will be created via v4l2_device_register_subdev() */
		break;
	default:
		return 0;
	}

	if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN) {
		vdev->entity.name = vdev->name;

		/* Needed just for backward compatibility with legacy MC API */
		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) {
			pr_warn("%s: media_device_register_entity failed\n",
				__func__);
			return ret;
		}
	}

	vdev->intf_devnode = media_devnode_create(vdev->v4l2_dev->mdev,
						  intf_type,
						  0, VIDEO_MAJOR,
						  vdev->minor);
	if (!vdev->intf_devnode) {
		media_device_unregister_entity(&vdev->entity);
		return -ENOMEM;
	}

	if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN) {
		struct media_link *link;

		link = media_create_intf_link(&vdev->entity,
					      &vdev->intf_devnode->intf,
					      MEDIA_LNK_FL_ENABLED |
					      MEDIA_LNK_FL_IMMUTABLE);
		if (!link) {
			media_devnode_remove(vdev->intf_devnode);
			media_device_unregister_entity(&vdev->entity);
			return -ENOMEM;
		}
	}

	/* FIXME: how to create the other interface links? */

#endif
	return 0;
}

int __video_register_device(struct video_device *vdev,
			    enum vfl_devnode_type 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;
	/* the device_caps field MUST be set for all but subdevs */
	if (WARN_ON(type != VFL_TYPE_SUBDEV && !vdev->device_caps))
		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_VIDEO:
		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;
	case VFL_TYPE_TOUCH:
		name_base = "v4l-touch";
		break;
	default:
		pr_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_VIDEO:
		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) {
		pr_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_devices[i] == NULL)
			break;
	if (i == VIDEO_NUM_DEVICES) {
		mutex_unlock(&videodev_lock);
		pr_err("could not get a free minor\n");
		return -ENFILE;
	}
#endif
	vdev->minor = i + minor_offset;
	vdev->num = nr;

	/* Should not happen since we thought this minor was free */
	if (WARN_ON(video_devices[vdev->minor])) {
		mutex_unlock(&videodev_lock);
		pr_err("video_device not empty!\n");
		return -ENFILE;
	}
	devnode_set(vdev);
	vdev->index = get_index(vdev);
	video_devices[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) {
		pr_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) {
		pr_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)
		pr_warn("%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);

	/* Part 5: Register the entity. */
	ret = video_register_media_controller(vdev);

	/* 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_devices[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);

/**
 *	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);
	if (test_bit(V4L2_FL_USES_V4L2_FH, &vdev->flags))
		v4l2_event_wake_all(vdev);
	device_unregister(&vdev->dev);
}
EXPORT_SYMBOL(video_unregister_device);

#if defined(CONFIG_MEDIA_CONTROLLER)

__must_check int video_device_pipeline_start(struct video_device *vdev,
					     struct media_pipeline *pipe)
{
	struct media_entity *entity = &vdev->entity;

	if (entity->num_pads != 1)
		return -ENODEV;

	return media_pipeline_start(entity, pipe);
}
EXPORT_SYMBOL_GPL(video_device_pipeline_start);

__must_check int __video_device_pipeline_start(struct video_device *vdev,
					       struct media_pipeline *pipe)
{
	struct media_entity *entity = &vdev->entity;

	if (entity->num_pads != 1)
		return -ENODEV;

	return __media_pipeline_start(entity, pipe);
}
EXPORT_SYMBOL_GPL(__video_device_pipeline_start);

void video_device_pipeline_stop(struct video_device *vdev)
{
	struct media_entity *entity = &vdev->entity;

	if (WARN_ON(entity->num_pads != 1))
		return;

	return media_pipeline_stop(entity);
}
EXPORT_SYMBOL_GPL(video_device_pipeline_stop);

void __video_device_pipeline_stop(struct video_device *vdev)
{
	struct media_entity *entity = &vdev->entity;

	if (WARN_ON(entity->num_pads != 1))
		return;

	return __media_pipeline_stop(entity);
}
EXPORT_SYMBOL_GPL(__video_device_pipeline_stop);

__must_check int video_device_pipeline_alloc_start(struct video_device *vdev)
{
	struct media_entity *entity = &vdev->entity;

	if (entity->num_pads != 1)
		return -ENODEV;

	return media_pipeline_alloc_start(entity);
}
EXPORT_SYMBOL_GPL(video_device_pipeline_alloc_start);

struct media_pipeline *video_device_pipeline(struct video_device *vdev)
{
	struct media_entity *entity = &vdev->entity;

	if (WARN_ON(entity->num_pads != 1))
		return NULL;

	return media_entity_pipeline(entity);
}
EXPORT_SYMBOL_GPL(video_device_pipeline);

#endif /* CONFIG_MEDIA_CONTROLLER */

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

	pr_info("Linux video capture interface: v2.00\n");
	ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
	if (ret < 0) {
		pr_warn("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);
		pr_warn("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);
}

subsys_initcall(videodev_init);
module_exit(videodev_exit)

MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@kernel.org>, Bill Dirks, Justin Schoeman, Gerd Knorr");
MODULE_DESCRIPTION("Video4Linux2 core driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);