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>
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"
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),
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];
88 /* Return the bitmap corresponding to vfl_type. */
89 static inline unsigned long *devnode_bits(int vfl_type)
91 return devnode_nums[vfl_type];
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)
123 EXPORT_SYMBOL(video_device_release);
125 void video_device_release_empty(struct video_device *vdev)
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 */
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. */
165 /* Mark device node number as free */
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);
176 /* Do not call v4l2_device_put if there is no release callback set.
177 * Drivers that have no v4l2_device release callback might free the
178 * v4l2_dev instance in the video_device release callback below, so we
179 * must perform this check here.
181 * TODO: In the long run all drivers that use v4l2_device should use the
182 * v4l2_device release callback. This check will then be unnecessary.
184 if (v4l2_dev && v4l2_dev->release == NULL)
187 /* Release video_device and perform other
188 cleanups as needed. */
191 /* Decrease v4l2_device refcount */
193 v4l2_device_put(v4l2_dev);
196 static struct class video_class = {
198 .dev_attrs = video_device_attrs,
201 struct video_device *video_devdata(struct file *file)
203 return video_device[iminor(file->f_path.dentry->d_inode)];
205 EXPORT_SYMBOL(video_devdata);
208 /* Priority handling */
210 static inline bool prio_is_valid(enum v4l2_priority prio)
212 return prio == V4L2_PRIORITY_BACKGROUND ||
213 prio == V4L2_PRIORITY_INTERACTIVE ||
214 prio == V4L2_PRIORITY_RECORD;
217 void v4l2_prio_init(struct v4l2_prio_state *global)
219 memset(global, 0, sizeof(*global));
221 EXPORT_SYMBOL(v4l2_prio_init);
223 int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local,
224 enum v4l2_priority new)
226 if (!prio_is_valid(new))
231 atomic_inc(&global->prios[new]);
232 if (prio_is_valid(*local))
233 atomic_dec(&global->prios[*local]);
237 EXPORT_SYMBOL(v4l2_prio_change);
239 void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local)
241 v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT);
243 EXPORT_SYMBOL(v4l2_prio_open);
245 void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local)
247 if (prio_is_valid(local))
248 atomic_dec(&global->prios[local]);
250 EXPORT_SYMBOL(v4l2_prio_close);
252 enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global)
254 if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0)
255 return V4L2_PRIORITY_RECORD;
256 if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0)
257 return V4L2_PRIORITY_INTERACTIVE;
258 if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0)
259 return V4L2_PRIORITY_BACKGROUND;
260 return V4L2_PRIORITY_UNSET;
262 EXPORT_SYMBOL(v4l2_prio_max);
264 int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local)
266 return (local < v4l2_prio_max(global)) ? -EBUSY : 0;
268 EXPORT_SYMBOL(v4l2_prio_check);
271 static ssize_t v4l2_read(struct file *filp, char __user *buf,
272 size_t sz, loff_t *off)
274 struct video_device *vdev = video_devdata(filp);
277 if (!vdev->fops->read)
279 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
281 if (video_is_registered(vdev))
282 ret = vdev->fops->read(filp, buf, sz, off);
284 mutex_unlock(vdev->lock);
288 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
289 size_t sz, loff_t *off)
291 struct video_device *vdev = video_devdata(filp);
294 if (!vdev->fops->write)
296 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
298 if (video_is_registered(vdev))
299 ret = vdev->fops->write(filp, buf, sz, off);
301 mutex_unlock(vdev->lock);
305 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
307 struct video_device *vdev = video_devdata(filp);
308 int ret = POLLERR | POLLHUP;
310 if (!vdev->fops->poll)
311 return DEFAULT_POLLMASK;
313 mutex_lock(vdev->lock);
314 if (video_is_registered(vdev))
315 ret = vdev->fops->poll(filp, poll);
317 mutex_unlock(vdev->lock);
321 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
323 struct video_device *vdev = video_devdata(filp);
326 if (vdev->fops->unlocked_ioctl) {
327 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
329 if (video_is_registered(vdev))
330 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
332 mutex_unlock(vdev->lock);
333 } else if (vdev->fops->ioctl) {
334 /* This code path is a replacement for the BKL. It is a major
335 * hack but it will have to do for those drivers that are not
336 * yet converted to use unlocked_ioctl.
338 * There are two options: if the driver implements struct
339 * v4l2_device, then the lock defined there is used to
340 * serialize the ioctls. Otherwise the v4l2 core lock defined
341 * below is used. This lock is really bad since it serializes
342 * completely independent devices.
344 * Both variants suffer from the same problem: if the driver
345 * sleeps, then it blocks all ioctls since the lock is still
346 * held. This is very common for VIDIOC_DQBUF since that
347 * normally waits for a frame to arrive. As a result any other
348 * ioctl calls will proceed very, very slowly since each call
349 * will have to wait for the VIDIOC_QBUF to finish. Things that
350 * should take 0.01s may now take 10-20 seconds.
352 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
353 * This actually works OK for videobuf-based drivers, since
354 * videobuf will take its own internal lock.
356 static DEFINE_MUTEX(v4l2_ioctl_mutex);
357 struct mutex *m = vdev->v4l2_dev ?
358 &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
360 if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
362 if (video_is_registered(vdev))
363 ret = vdev->fops->ioctl(filp, cmd, arg);
364 if (cmd != VIDIOC_DQBUF)
373 #define v4l2_get_unmapped_area NULL
375 static unsigned long v4l2_get_unmapped_area(struct file *filp,
376 unsigned long addr, unsigned long len, unsigned long pgoff,
379 struct video_device *vdev = video_devdata(filp);
381 if (!vdev->fops->get_unmapped_area)
383 if (!video_is_registered(vdev))
385 return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
389 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
391 struct video_device *vdev = video_devdata(filp);
394 if (!vdev->fops->mmap)
396 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
398 if (video_is_registered(vdev))
399 ret = vdev->fops->mmap(filp, vm);
401 mutex_unlock(vdev->lock);
405 /* Override for the open function */
406 static int v4l2_open(struct inode *inode, struct file *filp)
408 struct video_device *vdev;
411 /* Check if the video device is available */
412 mutex_lock(&videodev_lock);
413 vdev = video_devdata(filp);
414 /* return ENODEV if the video device has already been removed. */
415 if (vdev == NULL || !video_is_registered(vdev)) {
416 mutex_unlock(&videodev_lock);
419 /* and increase the device refcount */
421 mutex_unlock(&videodev_lock);
422 if (vdev->fops->open) {
423 if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
427 if (video_is_registered(vdev))
428 ret = vdev->fops->open(filp);
432 mutex_unlock(vdev->lock);
436 /* decrease the refcount in case of an error */
442 /* Override for the release function */
443 static int v4l2_release(struct inode *inode, struct file *filp)
445 struct video_device *vdev = video_devdata(filp);
448 if (vdev->fops->release) {
450 mutex_lock(vdev->lock);
451 vdev->fops->release(filp);
453 mutex_unlock(vdev->lock);
455 /* decrease the refcount unconditionally since the release()
456 return value is ignored. */
461 static const struct file_operations v4l2_fops = {
462 .owner = THIS_MODULE,
466 .get_unmapped_area = v4l2_get_unmapped_area,
468 .unlocked_ioctl = v4l2_ioctl,
470 .compat_ioctl = v4l2_compat_ioctl32,
472 .release = v4l2_release,
478 * get_index - assign stream index number based on parent device
479 * @vdev: video_device to assign index number to, vdev->parent should be assigned
481 * Note that when this is called the new device has not yet been registered
482 * in the video_device array, but it was able to obtain a minor number.
484 * This means that we can always obtain a free stream index number since
485 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
486 * use of the video_device array.
488 * Returns a free index number.
490 static int get_index(struct video_device *vdev)
492 /* This can be static since this function is called with the global
493 videodev_lock held. */
494 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
497 /* Some drivers do not set the parent. In that case always return 0. */
498 if (vdev->parent == NULL)
501 bitmap_zero(used, VIDEO_NUM_DEVICES);
503 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
504 if (video_device[i] != NULL &&
505 video_device[i]->parent == vdev->parent) {
506 set_bit(video_device[i]->index, used);
510 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
514 * __video_register_device - register video4linux devices
515 * @vdev: video device structure we want to register
516 * @type: type of device to register
517 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
519 * @warn_if_nr_in_use: warn if the desired device node number
520 * was already in use and another number was chosen instead.
521 * @owner: module that owns the video device node
523 * The registration code assigns minor numbers and device node numbers
524 * based on the requested type and registers the new device node with
527 * This function assumes that struct video_device was zeroed when it
528 * was allocated and does not contain any stale date.
530 * An error is returned if no free minor or device node number could be
531 * found, or if the registration of the device node failed.
533 * Zero is returned on success.
537 * %VFL_TYPE_GRABBER - A frame grabber
539 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
541 * %VFL_TYPE_RADIO - A radio card
543 * %VFL_TYPE_SUBDEV - A subdevice
545 int __video_register_device(struct video_device *vdev, int type, int nr,
546 int warn_if_nr_in_use, struct module *owner)
550 int minor_offset = 0;
551 int minor_cnt = VIDEO_NUM_DEVICES;
552 const char *name_base;
554 /* A minor value of -1 marks this video device as never
555 having been registered */
558 /* the release callback MUST be present */
559 WARN_ON(!vdev->release);
563 /* v4l2_fh support */
564 spin_lock_init(&vdev->fh_lock);
565 INIT_LIST_HEAD(&vdev->fh_list);
567 /* Part 1: check device type */
569 case VFL_TYPE_GRABBER:
578 case VFL_TYPE_SUBDEV:
579 name_base = "v4l-subdev";
582 printk(KERN_ERR "%s called with unknown type: %d\n",
587 vdev->vfl_type = type;
589 if (vdev->v4l2_dev) {
590 if (vdev->v4l2_dev->dev)
591 vdev->parent = vdev->v4l2_dev->dev;
592 if (vdev->ctrl_handler == NULL)
593 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
594 /* If the prio state pointer is NULL, then use the v4l2_device
596 if (vdev->prio == NULL)
597 vdev->prio = &vdev->v4l2_dev->prio;
600 /* Part 2: find a free minor, device node number and device index. */
601 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
602 /* Keep the ranges for the first four types for historical
604 * Newer devices (not yet in place) should use the range
605 * of 128-191 and just pick the first free minor there
608 case VFL_TYPE_GRABBER:
627 /* Pick a device node number */
628 mutex_lock(&videodev_lock);
629 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
631 nr = devnode_find(vdev, 0, minor_cnt);
632 if (nr == minor_cnt) {
633 printk(KERN_ERR "could not get a free device node number\n");
634 mutex_unlock(&videodev_lock);
637 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
638 /* 1-on-1 mapping of device node number to minor number */
641 /* The device node number and minor numbers are independent, so
642 we just find the first free minor number. */
643 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
644 if (video_device[i] == NULL)
646 if (i == VIDEO_NUM_DEVICES) {
647 mutex_unlock(&videodev_lock);
648 printk(KERN_ERR "could not get a free minor\n");
652 vdev->minor = i + minor_offset;
656 /* Should not happen since we thought this minor was free */
657 WARN_ON(video_device[vdev->minor] != NULL);
658 vdev->index = get_index(vdev);
659 mutex_unlock(&videodev_lock);
661 /* Part 3: Initialize the character device */
662 vdev->cdev = cdev_alloc();
663 if (vdev->cdev == NULL) {
667 vdev->cdev->ops = &v4l2_fops;
668 vdev->cdev->owner = owner;
669 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
671 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
677 /* Part 4: register the device with sysfs */
678 vdev->dev.class = &video_class;
679 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
681 vdev->dev.parent = vdev->parent;
682 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
683 ret = device_register(&vdev->dev);
685 printk(KERN_ERR "%s: device_register failed\n", __func__);
688 /* Register the release callback that will be called when the last
689 reference to the device goes away. */
690 vdev->dev.release = v4l2_device_release;
692 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
693 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
694 name_base, nr, video_device_node_name(vdev));
696 /* Increase v4l2_device refcount */
698 v4l2_device_get(vdev->v4l2_dev);
700 #if defined(CONFIG_MEDIA_CONTROLLER)
701 /* Part 5: Register the entity. */
702 if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
703 vdev->vfl_type != VFL_TYPE_SUBDEV) {
704 vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
705 vdev->entity.name = vdev->name;
706 vdev->entity.v4l.major = VIDEO_MAJOR;
707 vdev->entity.v4l.minor = vdev->minor;
708 ret = media_device_register_entity(vdev->v4l2_dev->mdev,
712 "%s: media_device_register_entity failed\n",
716 /* Part 6: Activate this minor. The char device can now be used. */
717 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
718 mutex_lock(&videodev_lock);
719 video_device[vdev->minor] = vdev;
720 mutex_unlock(&videodev_lock);
725 mutex_lock(&videodev_lock);
727 cdev_del(vdev->cdev);
729 mutex_unlock(&videodev_lock);
730 /* Mark this video device as never having been registered. */
734 EXPORT_SYMBOL(__video_register_device);
737 * video_unregister_device - unregister a video4linux device
738 * @vdev: the device to unregister
740 * This unregisters the passed device. Future open calls will
741 * be met with errors.
743 void video_unregister_device(struct video_device *vdev)
745 /* Check if vdev was ever registered at all */
746 if (!vdev || !video_is_registered(vdev))
749 mutex_lock(&videodev_lock);
750 /* This must be in a critical section to prevent a race with v4l2_open.
751 * Once this bit has been cleared video_get may never be called again.
753 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
754 mutex_unlock(&videodev_lock);
755 device_unregister(&vdev->dev);
757 EXPORT_SYMBOL(video_unregister_device);
760 * Initialise video for linux
762 static int __init videodev_init(void)
764 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
767 printk(KERN_INFO "Linux video capture interface: v2.00\n");
768 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
770 printk(KERN_WARNING "videodev: unable to get major %d\n",
775 ret = class_register(&video_class);
777 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
778 printk(KERN_WARNING "video_dev: class_register failed\n");
785 static void __exit videodev_exit(void)
787 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
789 class_unregister(&video_class);
790 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
793 module_init(videodev_init)
794 module_exit(videodev_exit)
796 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
797 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
798 MODULE_LICENSE("GPL");
799 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);