- 根目录:
- drivers
- media
- video
- v4l2-dev.c
/*
* 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 <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\n", 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\n", (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\n",
__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\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);
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\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);
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\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 */
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\n",
__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\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);
}
subsys_initcall(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:
*/