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>
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>
30 #include <media/v4l2-common.h>
31 #include <media/v4l2-device.h>
32 #include <media/v4l2-ioctl.h>
34 #define VIDEO_NUM_DEVICES 256
35 #define VIDEO_NAME "video4linux"
41 static ssize_t show_index(struct device *cd,
42 struct device_attribute *attr, char *buf)
44 struct video_device *vdev = to_video_device(cd);
46 return sprintf(buf, "%i\n", vdev->index);
49 static ssize_t show_name(struct device *cd,
50 struct device_attribute *attr, char *buf)
52 struct video_device *vdev = to_video_device(cd);
54 return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
57 static struct device_attribute video_device_attrs[] = {
58 __ATTR(name, S_IRUGO, show_name, NULL),
59 __ATTR(index, S_IRUGO, show_index, NULL),
66 static struct video_device *video_device[VIDEO_NUM_DEVICES];
67 static DEFINE_MUTEX(videodev_lock);
68 static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
70 /* Device node utility functions */
72 /* Note: these utility functions all assume that vfl_type is in the range
73 [0, VFL_TYPE_MAX-1]. */
75 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
76 /* Return the bitmap corresponding to vfl_type. */
77 static inline unsigned long *devnode_bits(int vfl_type)
79 /* Any types not assigned to fixed minor ranges must be mapped to
80 one single bitmap for the purposes of finding a free node number
81 since all those unassigned types use the same minor range. */
82 int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;
84 return devnode_nums[idx];
87 /* Return the bitmap corresponding to vfl_type. */
88 static inline unsigned long *devnode_bits(int vfl_type)
90 return devnode_nums[vfl_type];
94 /* Mark device node number vdev->num as used */
95 static inline void devnode_set(struct video_device *vdev)
97 set_bit(vdev->num, devnode_bits(vdev->vfl_type));
100 /* Mark device node number vdev->num as unused */
101 static inline void devnode_clear(struct video_device *vdev)
103 clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
106 /* Try to find a free device node number in the range [from, to> */
107 static inline int devnode_find(struct video_device *vdev, int from, int to)
109 return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
112 struct video_device *video_device_alloc(void)
114 return kzalloc(sizeof(struct video_device), GFP_KERNEL);
116 EXPORT_SYMBOL(video_device_alloc);
118 void video_device_release(struct video_device *vdev)
122 EXPORT_SYMBOL(video_device_release);
124 void video_device_release_empty(struct video_device *vdev)
127 /* Only valid when the video_device struct is a static. */
129 EXPORT_SYMBOL(video_device_release_empty);
131 static inline void video_get(struct video_device *vdev)
133 get_device(&vdev->dev);
136 static inline void video_put(struct video_device *vdev)
138 put_device(&vdev->dev);
141 /* Called when the last user of the video device exits. */
142 static void v4l2_device_release(struct device *cd)
144 struct video_device *vdev = to_video_device(cd);
145 struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
147 mutex_lock(&videodev_lock);
148 if (WARN_ON(video_device[vdev->minor] != vdev)) {
149 /* should not happen */
150 mutex_unlock(&videodev_lock);
154 /* Free up this device for reuse */
155 video_device[vdev->minor] = NULL;
157 /* Delete the cdev on this minor as well */
158 cdev_del(vdev->cdev);
159 /* Just in case some driver tries to access this from
160 the release() callback. */
163 /* Mark device node number as free */
166 mutex_unlock(&videodev_lock);
168 #if defined(CONFIG_MEDIA_CONTROLLER)
169 if (v4l2_dev && v4l2_dev->mdev &&
170 vdev->vfl_type != VFL_TYPE_SUBDEV)
171 media_device_unregister_entity(&vdev->entity);
174 /* Do not call v4l2_device_put if there is no release callback set.
175 * Drivers that have no v4l2_device release callback might free the
176 * v4l2_dev instance in the video_device release callback below, so we
177 * must perform this check here.
179 * TODO: In the long run all drivers that use v4l2_device should use the
180 * v4l2_device release callback. This check will then be unnecessary.
182 if (v4l2_dev && v4l2_dev->release == NULL)
185 /* Release video_device and perform other
186 cleanups as needed. */
189 /* Decrease v4l2_device refcount */
191 v4l2_device_put(v4l2_dev);
194 static struct class video_class = {
196 .dev_attrs = video_device_attrs,
199 struct video_device *video_devdata(struct file *file)
201 return video_device[iminor(file->f_path.dentry->d_inode)];
203 EXPORT_SYMBOL(video_devdata);
206 /* Priority handling */
208 static inline bool prio_is_valid(enum v4l2_priority prio)
210 return prio == V4L2_PRIORITY_BACKGROUND ||
211 prio == V4L2_PRIORITY_INTERACTIVE ||
212 prio == V4L2_PRIORITY_RECORD;
215 void v4l2_prio_init(struct v4l2_prio_state *global)
217 memset(global, 0, sizeof(*global));
219 EXPORT_SYMBOL(v4l2_prio_init);
221 int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local,
222 enum v4l2_priority new)
224 if (!prio_is_valid(new))
229 atomic_inc(&global->prios[new]);
230 if (prio_is_valid(*local))
231 atomic_dec(&global->prios[*local]);
235 EXPORT_SYMBOL(v4l2_prio_change);
237 void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local)
239 v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT);
241 EXPORT_SYMBOL(v4l2_prio_open);
243 void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local)
245 if (prio_is_valid(local))
246 atomic_dec(&global->prios[local]);
248 EXPORT_SYMBOL(v4l2_prio_close);
250 enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global)
252 if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0)
253 return V4L2_PRIORITY_RECORD;
254 if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0)
255 return V4L2_PRIORITY_INTERACTIVE;
256 if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0)
257 return V4L2_PRIORITY_BACKGROUND;
258 return V4L2_PRIORITY_UNSET;
260 EXPORT_SYMBOL(v4l2_prio_max);
262 int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local)
264 return (local < v4l2_prio_max(global)) ? -EBUSY : 0;
266 EXPORT_SYMBOL(v4l2_prio_check);
269 static ssize_t v4l2_read(struct file *filp, char __user *buf,
270 size_t sz, loff_t *off)
272 struct video_device *vdev = video_devdata(filp);
275 if (!vdev->fops->read)
277 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
279 if (video_is_registered(vdev))
280 ret = vdev->fops->read(filp, buf, sz, off);
282 mutex_unlock(vdev->lock);
286 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
287 size_t sz, loff_t *off)
289 struct video_device *vdev = video_devdata(filp);
292 if (!vdev->fops->write)
294 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
296 if (video_is_registered(vdev))
297 ret = vdev->fops->write(filp, buf, sz, off);
299 mutex_unlock(vdev->lock);
303 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
305 struct video_device *vdev = video_devdata(filp);
306 int ret = POLLERR | POLLHUP;
308 if (!vdev->fops->poll)
309 return DEFAULT_POLLMASK;
311 mutex_lock(vdev->lock);
312 if (video_is_registered(vdev))
313 ret = vdev->fops->poll(filp, poll);
315 mutex_unlock(vdev->lock);
319 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
321 struct video_device *vdev = video_devdata(filp);
324 if (vdev->fops->unlocked_ioctl) {
325 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
327 if (video_is_registered(vdev))
328 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
330 mutex_unlock(vdev->lock);
331 } else if (vdev->fops->ioctl) {
332 /* This code path is a replacement for the BKL. It is a major
333 * hack but it will have to do for those drivers that are not
334 * yet converted to use unlocked_ioctl.
336 * There are two options: if the driver implements struct
337 * v4l2_device, then the lock defined there is used to
338 * serialize the ioctls. Otherwise the v4l2 core lock defined
339 * below is used. This lock is really bad since it serializes
340 * completely independent devices.
342 * Both variants suffer from the same problem: if the driver
343 * sleeps, then it blocks all ioctls since the lock is still
344 * held. This is very common for VIDIOC_DQBUF since that
345 * normally waits for a frame to arrive. As a result any other
346 * ioctl calls will proceed very, very slowly since each call
347 * will have to wait for the VIDIOC_QBUF to finish. Things that
348 * should take 0.01s may now take 10-20 seconds.
350 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
351 * This actually works OK for videobuf-based drivers, since
352 * videobuf will take its own internal lock.
354 static DEFINE_MUTEX(v4l2_ioctl_mutex);
355 struct mutex *m = vdev->v4l2_dev ?
356 &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
358 if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
360 if (video_is_registered(vdev))
361 ret = vdev->fops->ioctl(filp, cmd, arg);
362 if (cmd != VIDIOC_DQBUF)
371 #define v4l2_get_unmapped_area NULL
373 static unsigned long v4l2_get_unmapped_area(struct file *filp,
374 unsigned long addr, unsigned long len, unsigned long pgoff,
377 struct video_device *vdev = video_devdata(filp);
379 if (!vdev->fops->get_unmapped_area)
381 if (!video_is_registered(vdev))
383 return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
387 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
389 struct video_device *vdev = video_devdata(filp);
392 if (!vdev->fops->mmap)
394 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
396 if (video_is_registered(vdev))
397 ret = vdev->fops->mmap(filp, vm);
399 mutex_unlock(vdev->lock);
403 /* Override for the open function */
404 static int v4l2_open(struct inode *inode, struct file *filp)
406 struct video_device *vdev;
409 /* Check if the video device is available */
410 mutex_lock(&videodev_lock);
411 vdev = video_devdata(filp);
412 /* return ENODEV if the video device has already been removed. */
413 if (vdev == NULL || !video_is_registered(vdev)) {
414 mutex_unlock(&videodev_lock);
417 /* and increase the device refcount */
419 mutex_unlock(&videodev_lock);
420 if (vdev->fops->open) {
421 if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
425 if (video_is_registered(vdev))
426 ret = vdev->fops->open(filp);
430 mutex_unlock(vdev->lock);
434 /* decrease the refcount in case of an error */
440 /* Override for the release function */
441 static int v4l2_release(struct inode *inode, struct file *filp)
443 struct video_device *vdev = video_devdata(filp);
446 if (vdev->fops->release) {
448 mutex_lock(vdev->lock);
449 vdev->fops->release(filp);
451 mutex_unlock(vdev->lock);
453 /* decrease the refcount unconditionally since the release()
454 return value is ignored. */
459 static const struct file_operations v4l2_fops = {
460 .owner = THIS_MODULE,
464 .get_unmapped_area = v4l2_get_unmapped_area,
466 .unlocked_ioctl = v4l2_ioctl,
468 .compat_ioctl = v4l2_compat_ioctl32,
470 .release = v4l2_release,
476 * get_index - assign stream index number based on parent device
477 * @vdev: video_device to assign index number to, vdev->parent should be assigned
479 * Note that when this is called the new device has not yet been registered
480 * in the video_device array, but it was able to obtain a minor number.
482 * This means that we can always obtain a free stream index number since
483 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
484 * use of the video_device array.
486 * Returns a free index number.
488 static int get_index(struct video_device *vdev)
490 /* This can be static since this function is called with the global
491 videodev_lock held. */
492 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
495 /* Some drivers do not set the parent. In that case always return 0. */
496 if (vdev->parent == NULL)
499 bitmap_zero(used, VIDEO_NUM_DEVICES);
501 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
502 if (video_device[i] != NULL &&
503 video_device[i]->parent == vdev->parent) {
504 set_bit(video_device[i]->index, used);
508 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
512 * __video_register_device - register video4linux devices
513 * @vdev: video device structure we want to register
514 * @type: type of device to register
515 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
517 * @warn_if_nr_in_use: warn if the desired device node number
518 * was already in use and another number was chosen instead.
519 * @owner: module that owns the video device node
521 * The registration code assigns minor numbers and device node numbers
522 * based on the requested type and registers the new device node with
525 * This function assumes that struct video_device was zeroed when it
526 * was allocated and does not contain any stale date.
528 * An error is returned if no free minor or device node number could be
529 * found, or if the registration of the device node failed.
531 * Zero is returned on success.
535 * %VFL_TYPE_GRABBER - A frame grabber
537 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
539 * %VFL_TYPE_RADIO - A radio card
541 * %VFL_TYPE_SUBDEV - A subdevice
543 int __video_register_device(struct video_device *vdev, int type, int nr,
544 int warn_if_nr_in_use, struct module *owner)
548 int minor_offset = 0;
549 int minor_cnt = VIDEO_NUM_DEVICES;
550 const char *name_base;
552 /* A minor value of -1 marks this video device as never
553 having been registered */
556 /* the release callback MUST be present */
557 if (WARN_ON(!vdev->release))
560 /* v4l2_fh support */
561 spin_lock_init(&vdev->fh_lock);
562 INIT_LIST_HEAD(&vdev->fh_list);
564 /* Part 1: check device type */
566 case VFL_TYPE_GRABBER:
575 case VFL_TYPE_SUBDEV:
576 name_base = "v4l-subdev";
579 printk(KERN_ERR "%s called with unknown type: %d\n",
584 vdev->vfl_type = type;
586 if (vdev->v4l2_dev) {
587 if (vdev->v4l2_dev->dev)
588 vdev->parent = vdev->v4l2_dev->dev;
589 if (vdev->ctrl_handler == NULL)
590 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
591 /* If the prio state pointer is NULL, then use the v4l2_device
593 if (vdev->prio == NULL)
594 vdev->prio = &vdev->v4l2_dev->prio;
597 /* Part 2: find a free minor, device node number and device index. */
598 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
599 /* Keep the ranges for the first four types for historical
601 * Newer devices (not yet in place) should use the range
602 * of 128-191 and just pick the first free minor there
605 case VFL_TYPE_GRABBER:
624 /* Pick a device node number */
625 mutex_lock(&videodev_lock);
626 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
628 nr = devnode_find(vdev, 0, minor_cnt);
629 if (nr == minor_cnt) {
630 printk(KERN_ERR "could not get a free device node number\n");
631 mutex_unlock(&videodev_lock);
634 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
635 /* 1-on-1 mapping of device node number to minor number */
638 /* The device node number and minor numbers are independent, so
639 we just find the first free minor number. */
640 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
641 if (video_device[i] == NULL)
643 if (i == VIDEO_NUM_DEVICES) {
644 mutex_unlock(&videodev_lock);
645 printk(KERN_ERR "could not get a free minor\n");
649 vdev->minor = i + minor_offset;
653 /* Should not happen since we thought this minor was free */
654 WARN_ON(video_device[vdev->minor] != NULL);
655 vdev->index = get_index(vdev);
656 mutex_unlock(&videodev_lock);
658 /* Part 3: Initialize the character device */
659 vdev->cdev = cdev_alloc();
660 if (vdev->cdev == NULL) {
664 vdev->cdev->ops = &v4l2_fops;
665 vdev->cdev->owner = owner;
666 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
668 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
674 /* Part 4: register the device with sysfs */
675 vdev->dev.class = &video_class;
676 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
678 vdev->dev.parent = vdev->parent;
679 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
680 ret = device_register(&vdev->dev);
682 printk(KERN_ERR "%s: device_register failed\n", __func__);
685 /* Register the release callback that will be called when the last
686 reference to the device goes away. */
687 vdev->dev.release = v4l2_device_release;
689 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
690 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
691 name_base, nr, video_device_node_name(vdev));
693 /* Increase v4l2_device refcount */
695 v4l2_device_get(vdev->v4l2_dev);
697 #if defined(CONFIG_MEDIA_CONTROLLER)
698 /* Part 5: Register the entity. */
699 if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
700 vdev->vfl_type != VFL_TYPE_SUBDEV) {
701 vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
702 vdev->entity.name = vdev->name;
703 vdev->entity.info.v4l.major = VIDEO_MAJOR;
704 vdev->entity.info.v4l.minor = vdev->minor;
705 ret = media_device_register_entity(vdev->v4l2_dev->mdev,
709 "%s: media_device_register_entity failed\n",
713 /* Part 6: Activate this minor. The char device can now be used. */
714 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
715 mutex_lock(&videodev_lock);
716 video_device[vdev->minor] = vdev;
717 mutex_unlock(&videodev_lock);
722 mutex_lock(&videodev_lock);
724 cdev_del(vdev->cdev);
726 mutex_unlock(&videodev_lock);
727 /* Mark this video device as never having been registered. */
731 EXPORT_SYMBOL(__video_register_device);
734 * video_unregister_device - unregister a video4linux device
735 * @vdev: the device to unregister
737 * This unregisters the passed device. Future open calls will
738 * be met with errors.
740 void video_unregister_device(struct video_device *vdev)
742 /* Check if vdev was ever registered at all */
743 if (!vdev || !video_is_registered(vdev))
746 mutex_lock(&videodev_lock);
747 /* This must be in a critical section to prevent a race with v4l2_open.
748 * Once this bit has been cleared video_get may never be called again.
750 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
751 mutex_unlock(&videodev_lock);
752 device_unregister(&vdev->dev);
754 EXPORT_SYMBOL(video_unregister_device);
757 * Initialise video for linux
759 static int __init videodev_init(void)
761 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
764 printk(KERN_INFO "Linux video capture interface: v2.00\n");
765 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
767 printk(KERN_WARNING "videodev: unable to get major %d\n",
772 ret = class_register(&video_class);
774 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
775 printk(KERN_WARNING "video_dev: class_register failed\n");
782 static void __exit videodev_exit(void)
784 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
786 class_unregister(&video_class);
787 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
790 subsys_initcall(videodev_init);
791 module_exit(videodev_exit)
793 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
794 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
795 MODULE_LICENSE("GPL");
796 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);