Merge remote-tracking branch 'moduleh/module.h-split'
[linux-2.6/next.git] / drivers / media / video / v4l2-dev.c
blob06f14008b346443a50a55cc58c2a2009e1664ecd
1 /*
2 * Video capture interface for Linux version 2
4 * A generic video device interface for the LINUX operating system
5 * using a set of device structures/vectors for low level operations.
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
12 * Authors: Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
13 * Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
15 * Fixes: 20000516 Claudio Matsuoka <claudio@conectiva.com>
16 * - Added procfs support
19 #include <linux/module.h>
20 #include <linux/types.h>
21 #include <linux/kernel.h>
22 #include <linux/mm.h>
23 #include <linux/string.h>
24 #include <linux/errno.h>
25 #include <linux/init.h>
26 #include <linux/kmod.h>
27 #include <linux/slab.h>
28 #include <asm/uaccess.h>
29 #include <asm/system.h>
31 #include <media/v4l2-common.h>
32 #include <media/v4l2-device.h>
33 #include <media/v4l2-ioctl.h>
35 #define VIDEO_NUM_DEVICES 256
36 #define VIDEO_NAME "video4linux"
39 * sysfs stuff
42 static ssize_t show_index(struct device *cd,
43 struct device_attribute *attr, char *buf)
45 struct video_device *vdev = to_video_device(cd);
47 return sprintf(buf, "%i\n", vdev->index);
50 static ssize_t show_name(struct device *cd,
51 struct device_attribute *attr, char *buf)
53 struct video_device *vdev = to_video_device(cd);
55 return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
58 static struct device_attribute video_device_attrs[] = {
59 __ATTR(name, S_IRUGO, show_name, NULL),
60 __ATTR(index, S_IRUGO, show_index, NULL),
61 __ATTR_NULL
65 * Active devices
67 static struct video_device *video_device[VIDEO_NUM_DEVICES];
68 static DEFINE_MUTEX(videodev_lock);
69 static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
71 /* Device node utility functions */
73 /* Note: these utility functions all assume that vfl_type is in the range
74 [0, VFL_TYPE_MAX-1]. */
76 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
77 /* Return the bitmap corresponding to vfl_type. */
78 static inline unsigned long *devnode_bits(int vfl_type)
80 /* Any types not assigned to fixed minor ranges must be mapped to
81 one single bitmap for the purposes of finding a free node number
82 since all those unassigned types use the same minor range. */
83 int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;
85 return devnode_nums[idx];
87 #else
88 /* Return the bitmap corresponding to vfl_type. */
89 static inline unsigned long *devnode_bits(int vfl_type)
91 return devnode_nums[vfl_type];
93 #endif
95 /* Mark device node number vdev->num as used */
96 static inline void devnode_set(struct video_device *vdev)
98 set_bit(vdev->num, devnode_bits(vdev->vfl_type));
101 /* Mark device node number vdev->num as unused */
102 static inline void devnode_clear(struct video_device *vdev)
104 clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
107 /* Try to find a free device node number in the range [from, to> */
108 static inline int devnode_find(struct video_device *vdev, int from, int to)
110 return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
113 struct video_device *video_device_alloc(void)
115 return kzalloc(sizeof(struct video_device), GFP_KERNEL);
117 EXPORT_SYMBOL(video_device_alloc);
119 void video_device_release(struct video_device *vdev)
121 kfree(vdev);
123 EXPORT_SYMBOL(video_device_release);
125 void video_device_release_empty(struct video_device *vdev)
127 /* Do nothing */
128 /* Only valid when the video_device struct is a static. */
130 EXPORT_SYMBOL(video_device_release_empty);
132 static inline void video_get(struct video_device *vdev)
134 get_device(&vdev->dev);
137 static inline void video_put(struct video_device *vdev)
139 put_device(&vdev->dev);
142 /* Called when the last user of the video device exits. */
143 static void v4l2_device_release(struct device *cd)
145 struct video_device *vdev = to_video_device(cd);
146 struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
148 mutex_lock(&videodev_lock);
149 if (video_device[vdev->minor] != vdev) {
150 mutex_unlock(&videodev_lock);
151 /* should not happen */
152 WARN_ON(1);
153 return;
156 /* Free up this device for reuse */
157 video_device[vdev->minor] = NULL;
159 /* Delete the cdev on this minor as well */
160 cdev_del(vdev->cdev);
161 /* Just in case some driver tries to access this from
162 the release() callback. */
163 vdev->cdev = NULL;
165 /* Mark device node number as free */
166 devnode_clear(vdev);
168 mutex_unlock(&videodev_lock);
170 #if defined(CONFIG_MEDIA_CONTROLLER)
171 if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
172 vdev->vfl_type != VFL_TYPE_SUBDEV)
173 media_device_unregister_entity(&vdev->entity);
174 #endif
176 /* Release video_device and perform other
177 cleanups as needed. */
178 vdev->release(vdev);
180 /* Decrease v4l2_device refcount */
181 if (v4l2_dev)
182 v4l2_device_put(v4l2_dev);
185 static struct class video_class = {
186 .name = VIDEO_NAME,
187 .dev_attrs = video_device_attrs,
190 struct video_device *video_devdata(struct file *file)
192 return video_device[iminor(file->f_path.dentry->d_inode)];
194 EXPORT_SYMBOL(video_devdata);
197 /* Priority handling */
199 static inline bool prio_is_valid(enum v4l2_priority prio)
201 return prio == V4L2_PRIORITY_BACKGROUND ||
202 prio == V4L2_PRIORITY_INTERACTIVE ||
203 prio == V4L2_PRIORITY_RECORD;
206 void v4l2_prio_init(struct v4l2_prio_state *global)
208 memset(global, 0, sizeof(*global));
210 EXPORT_SYMBOL(v4l2_prio_init);
212 int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local,
213 enum v4l2_priority new)
215 if (!prio_is_valid(new))
216 return -EINVAL;
217 if (*local == new)
218 return 0;
220 atomic_inc(&global->prios[new]);
221 if (prio_is_valid(*local))
222 atomic_dec(&global->prios[*local]);
223 *local = new;
224 return 0;
226 EXPORT_SYMBOL(v4l2_prio_change);
228 void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local)
230 v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT);
232 EXPORT_SYMBOL(v4l2_prio_open);
234 void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local)
236 if (prio_is_valid(local))
237 atomic_dec(&global->prios[local]);
239 EXPORT_SYMBOL(v4l2_prio_close);
241 enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global)
243 if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0)
244 return V4L2_PRIORITY_RECORD;
245 if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0)
246 return V4L2_PRIORITY_INTERACTIVE;
247 if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0)
248 return V4L2_PRIORITY_BACKGROUND;
249 return V4L2_PRIORITY_UNSET;
251 EXPORT_SYMBOL(v4l2_prio_max);
253 int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local)
255 return (local < v4l2_prio_max(global)) ? -EBUSY : 0;
257 EXPORT_SYMBOL(v4l2_prio_check);
260 static ssize_t v4l2_read(struct file *filp, char __user *buf,
261 size_t sz, loff_t *off)
263 struct video_device *vdev = video_devdata(filp);
264 int ret = -ENODEV;
266 if (!vdev->fops->read)
267 return -EINVAL;
268 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
269 return -ERESTARTSYS;
270 if (video_is_registered(vdev))
271 ret = vdev->fops->read(filp, buf, sz, off);
272 if (vdev->lock)
273 mutex_unlock(vdev->lock);
274 return ret;
277 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
278 size_t sz, loff_t *off)
280 struct video_device *vdev = video_devdata(filp);
281 int ret = -ENODEV;
283 if (!vdev->fops->write)
284 return -EINVAL;
285 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
286 return -ERESTARTSYS;
287 if (video_is_registered(vdev))
288 ret = vdev->fops->write(filp, buf, sz, off);
289 if (vdev->lock)
290 mutex_unlock(vdev->lock);
291 return ret;
294 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
296 struct video_device *vdev = video_devdata(filp);
297 int ret = POLLERR | POLLHUP;
299 if (!vdev->fops->poll)
300 return DEFAULT_POLLMASK;
301 if (vdev->lock)
302 mutex_lock(vdev->lock);
303 if (video_is_registered(vdev))
304 ret = vdev->fops->poll(filp, poll);
305 if (vdev->lock)
306 mutex_unlock(vdev->lock);
307 return ret;
310 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
312 struct video_device *vdev = video_devdata(filp);
313 int ret = -ENODEV;
315 if (vdev->fops->unlocked_ioctl) {
316 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
317 return -ERESTARTSYS;
318 if (video_is_registered(vdev))
319 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
320 if (vdev->lock)
321 mutex_unlock(vdev->lock);
322 } else if (vdev->fops->ioctl) {
323 /* This code path is a replacement for the BKL. It is a major
324 * hack but it will have to do for those drivers that are not
325 * yet converted to use unlocked_ioctl.
327 * There are two options: if the driver implements struct
328 * v4l2_device, then the lock defined there is used to
329 * serialize the ioctls. Otherwise the v4l2 core lock defined
330 * below is used. This lock is really bad since it serializes
331 * completely independent devices.
333 * Both variants suffer from the same problem: if the driver
334 * sleeps, then it blocks all ioctls since the lock is still
335 * held. This is very common for VIDIOC_DQBUF since that
336 * normally waits for a frame to arrive. As a result any other
337 * ioctl calls will proceed very, very slowly since each call
338 * will have to wait for the VIDIOC_QBUF to finish. Things that
339 * should take 0.01s may now take 10-20 seconds.
341 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
342 * This actually works OK for videobuf-based drivers, since
343 * videobuf will take its own internal lock.
345 static DEFINE_MUTEX(v4l2_ioctl_mutex);
346 struct mutex *m = vdev->v4l2_dev ?
347 &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
349 if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
350 return -ERESTARTSYS;
351 if (video_is_registered(vdev))
352 ret = vdev->fops->ioctl(filp, cmd, arg);
353 if (cmd != VIDIOC_DQBUF)
354 mutex_unlock(m);
355 } else
356 ret = -ENOTTY;
358 return ret;
361 #ifdef CONFIG_MMU
362 #define v4l2_get_unmapped_area NULL
363 #else
364 static unsigned long v4l2_get_unmapped_area(struct file *filp,
365 unsigned long addr, unsigned long len, unsigned long pgoff,
366 unsigned long flags)
368 struct video_device *vdev = video_devdata(filp);
370 if (!vdev->fops->get_unmapped_area)
371 return -ENOSYS;
372 if (!video_is_registered(vdev))
373 return -ENODEV;
374 return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
376 #endif
378 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
380 struct video_device *vdev = video_devdata(filp);
381 int ret = -ENODEV;
383 if (!vdev->fops->mmap)
384 return ret;
385 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
386 return -ERESTARTSYS;
387 if (video_is_registered(vdev))
388 ret = vdev->fops->mmap(filp, vm);
389 if (vdev->lock)
390 mutex_unlock(vdev->lock);
391 return ret;
394 /* Override for the open function */
395 static int v4l2_open(struct inode *inode, struct file *filp)
397 struct video_device *vdev;
398 int ret = 0;
400 /* Check if the video device is available */
401 mutex_lock(&videodev_lock);
402 vdev = video_devdata(filp);
403 /* return ENODEV if the video device has already been removed. */
404 if (vdev == NULL || !video_is_registered(vdev)) {
405 mutex_unlock(&videodev_lock);
406 return -ENODEV;
408 /* and increase the device refcount */
409 video_get(vdev);
410 mutex_unlock(&videodev_lock);
411 if (vdev->fops->open) {
412 if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
413 ret = -ERESTARTSYS;
414 goto err;
416 if (video_is_registered(vdev))
417 ret = vdev->fops->open(filp);
418 else
419 ret = -ENODEV;
420 if (vdev->lock)
421 mutex_unlock(vdev->lock);
424 err:
425 /* decrease the refcount in case of an error */
426 if (ret)
427 video_put(vdev);
428 return ret;
431 /* Override for the release function */
432 static int v4l2_release(struct inode *inode, struct file *filp)
434 struct video_device *vdev = video_devdata(filp);
435 int ret = 0;
437 if (vdev->fops->release) {
438 if (vdev->lock)
439 mutex_lock(vdev->lock);
440 vdev->fops->release(filp);
441 if (vdev->lock)
442 mutex_unlock(vdev->lock);
444 /* decrease the refcount unconditionally since the release()
445 return value is ignored. */
446 video_put(vdev);
447 return ret;
450 static const struct file_operations v4l2_fops = {
451 .owner = THIS_MODULE,
452 .read = v4l2_read,
453 .write = v4l2_write,
454 .open = v4l2_open,
455 .get_unmapped_area = v4l2_get_unmapped_area,
456 .mmap = v4l2_mmap,
457 .unlocked_ioctl = v4l2_ioctl,
458 #ifdef CONFIG_COMPAT
459 .compat_ioctl = v4l2_compat_ioctl32,
460 #endif
461 .release = v4l2_release,
462 .poll = v4l2_poll,
463 .llseek = no_llseek,
467 * get_index - assign stream index number based on parent device
468 * @vdev: video_device to assign index number to, vdev->parent should be assigned
470 * Note that when this is called the new device has not yet been registered
471 * in the video_device array, but it was able to obtain a minor number.
473 * This means that we can always obtain a free stream index number since
474 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
475 * use of the video_device array.
477 * Returns a free index number.
479 static int get_index(struct video_device *vdev)
481 /* This can be static since this function is called with the global
482 videodev_lock held. */
483 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
484 int i;
486 /* Some drivers do not set the parent. In that case always return 0. */
487 if (vdev->parent == NULL)
488 return 0;
490 bitmap_zero(used, VIDEO_NUM_DEVICES);
492 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
493 if (video_device[i] != NULL &&
494 video_device[i]->parent == vdev->parent) {
495 set_bit(video_device[i]->index, used);
499 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
503 * __video_register_device - register video4linux devices
504 * @vdev: video device structure we want to register
505 * @type: type of device to register
506 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
507 * -1 == first free)
508 * @warn_if_nr_in_use: warn if the desired device node number
509 * was already in use and another number was chosen instead.
510 * @owner: module that owns the video device node
512 * The registration code assigns minor numbers and device node numbers
513 * based on the requested type and registers the new device node with
514 * the kernel.
516 * This function assumes that struct video_device was zeroed when it
517 * was allocated and does not contain any stale date.
519 * An error is returned if no free minor or device node number could be
520 * found, or if the registration of the device node failed.
522 * Zero is returned on success.
524 * Valid types are
526 * %VFL_TYPE_GRABBER - A frame grabber
528 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
530 * %VFL_TYPE_RADIO - A radio card
532 * %VFL_TYPE_SUBDEV - A subdevice
534 int __video_register_device(struct video_device *vdev, int type, int nr,
535 int warn_if_nr_in_use, struct module *owner)
537 int i = 0;
538 int ret;
539 int minor_offset = 0;
540 int minor_cnt = VIDEO_NUM_DEVICES;
541 const char *name_base;
543 /* A minor value of -1 marks this video device as never
544 having been registered */
545 vdev->minor = -1;
547 /* the release callback MUST be present */
548 WARN_ON(!vdev->release);
549 if (!vdev->release)
550 return -EINVAL;
552 /* v4l2_fh support */
553 spin_lock_init(&vdev->fh_lock);
554 INIT_LIST_HEAD(&vdev->fh_list);
556 /* Part 1: check device type */
557 switch (type) {
558 case VFL_TYPE_GRABBER:
559 name_base = "video";
560 break;
561 case VFL_TYPE_VBI:
562 name_base = "vbi";
563 break;
564 case VFL_TYPE_RADIO:
565 name_base = "radio";
566 break;
567 case VFL_TYPE_SUBDEV:
568 name_base = "v4l-subdev";
569 break;
570 default:
571 printk(KERN_ERR "%s called with unknown type: %d\n",
572 __func__, type);
573 return -EINVAL;
576 vdev->vfl_type = type;
577 vdev->cdev = NULL;
578 if (vdev->v4l2_dev) {
579 if (vdev->v4l2_dev->dev)
580 vdev->parent = vdev->v4l2_dev->dev;
581 if (vdev->ctrl_handler == NULL)
582 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
583 /* If the prio state pointer is NULL, then use the v4l2_device
584 prio state. */
585 if (vdev->prio == NULL)
586 vdev->prio = &vdev->v4l2_dev->prio;
589 /* Part 2: find a free minor, device node number and device index. */
590 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
591 /* Keep the ranges for the first four types for historical
592 * reasons.
593 * Newer devices (not yet in place) should use the range
594 * of 128-191 and just pick the first free minor there
595 * (new style). */
596 switch (type) {
597 case VFL_TYPE_GRABBER:
598 minor_offset = 0;
599 minor_cnt = 64;
600 break;
601 case VFL_TYPE_RADIO:
602 minor_offset = 64;
603 minor_cnt = 64;
604 break;
605 case VFL_TYPE_VBI:
606 minor_offset = 224;
607 minor_cnt = 32;
608 break;
609 default:
610 minor_offset = 128;
611 minor_cnt = 64;
612 break;
614 #endif
616 /* Pick a device node number */
617 mutex_lock(&videodev_lock);
618 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
619 if (nr == minor_cnt)
620 nr = devnode_find(vdev, 0, minor_cnt);
621 if (nr == minor_cnt) {
622 printk(KERN_ERR "could not get a free device node number\n");
623 mutex_unlock(&videodev_lock);
624 return -ENFILE;
626 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
627 /* 1-on-1 mapping of device node number to minor number */
628 i = nr;
629 #else
630 /* The device node number and minor numbers are independent, so
631 we just find the first free minor number. */
632 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
633 if (video_device[i] == NULL)
634 break;
635 if (i == VIDEO_NUM_DEVICES) {
636 mutex_unlock(&videodev_lock);
637 printk(KERN_ERR "could not get a free minor\n");
638 return -ENFILE;
640 #endif
641 vdev->minor = i + minor_offset;
642 vdev->num = nr;
643 devnode_set(vdev);
645 /* Should not happen since we thought this minor was free */
646 WARN_ON(video_device[vdev->minor] != NULL);
647 vdev->index = get_index(vdev);
648 mutex_unlock(&videodev_lock);
650 /* Part 3: Initialize the character device */
651 vdev->cdev = cdev_alloc();
652 if (vdev->cdev == NULL) {
653 ret = -ENOMEM;
654 goto cleanup;
656 vdev->cdev->ops = &v4l2_fops;
657 vdev->cdev->owner = owner;
658 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
659 if (ret < 0) {
660 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
661 kfree(vdev->cdev);
662 vdev->cdev = NULL;
663 goto cleanup;
666 /* Part 4: register the device with sysfs */
667 vdev->dev.class = &video_class;
668 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
669 if (vdev->parent)
670 vdev->dev.parent = vdev->parent;
671 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
672 ret = device_register(&vdev->dev);
673 if (ret < 0) {
674 printk(KERN_ERR "%s: device_register failed\n", __func__);
675 goto cleanup;
677 /* Register the release callback that will be called when the last
678 reference to the device goes away. */
679 vdev->dev.release = v4l2_device_release;
681 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
682 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
683 name_base, nr, video_device_node_name(vdev));
685 /* Increase v4l2_device refcount */
686 if (vdev->v4l2_dev)
687 v4l2_device_get(vdev->v4l2_dev);
689 #if defined(CONFIG_MEDIA_CONTROLLER)
690 /* Part 5: Register the entity. */
691 if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
692 vdev->vfl_type != VFL_TYPE_SUBDEV) {
693 vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
694 vdev->entity.name = vdev->name;
695 vdev->entity.v4l.major = VIDEO_MAJOR;
696 vdev->entity.v4l.minor = vdev->minor;
697 ret = media_device_register_entity(vdev->v4l2_dev->mdev,
698 &vdev->entity);
699 if (ret < 0)
700 printk(KERN_WARNING
701 "%s: media_device_register_entity failed\n",
702 __func__);
704 #endif
705 /* Part 6: Activate this minor. The char device can now be used. */
706 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
707 mutex_lock(&videodev_lock);
708 video_device[vdev->minor] = vdev;
709 mutex_unlock(&videodev_lock);
711 return 0;
713 cleanup:
714 mutex_lock(&videodev_lock);
715 if (vdev->cdev)
716 cdev_del(vdev->cdev);
717 devnode_clear(vdev);
718 mutex_unlock(&videodev_lock);
719 /* Mark this video device as never having been registered. */
720 vdev->minor = -1;
721 return ret;
723 EXPORT_SYMBOL(__video_register_device);
726 * video_unregister_device - unregister a video4linux device
727 * @vdev: the device to unregister
729 * This unregisters the passed device. Future open calls will
730 * be met with errors.
732 void video_unregister_device(struct video_device *vdev)
734 /* Check if vdev was ever registered at all */
735 if (!vdev || !video_is_registered(vdev))
736 return;
738 mutex_lock(&videodev_lock);
739 /* This must be in a critical section to prevent a race with v4l2_open.
740 * Once this bit has been cleared video_get may never be called again.
742 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
743 mutex_unlock(&videodev_lock);
744 device_unregister(&vdev->dev);
746 EXPORT_SYMBOL(video_unregister_device);
749 * Initialise video for linux
751 static int __init videodev_init(void)
753 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
754 int ret;
756 printk(KERN_INFO "Linux video capture interface: v2.00\n");
757 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
758 if (ret < 0) {
759 printk(KERN_WARNING "videodev: unable to get major %d\n",
760 VIDEO_MAJOR);
761 return ret;
764 ret = class_register(&video_class);
765 if (ret < 0) {
766 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
767 printk(KERN_WARNING "video_dev: class_register failed\n");
768 return -EIO;
771 return 0;
774 static void __exit videodev_exit(void)
776 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
778 class_unregister(&video_class);
779 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
782 module_init(videodev_init)
783 module_exit(videodev_exit)
785 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
786 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
787 MODULE_LICENSE("GPL");
788 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);
792 * Local variables:
793 * c-basic-offset: 8
794 * End: