参照元†
- struct video_device *vdev
- int type
- int nr
- int warn_if_nr_in_use
- struct module *owner
返り値†
/**
* __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);
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);
コメント†