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);
147 mutex_lock(&videodev_lock);
148 if (video_device[vdev->minor] != vdev) {
149 mutex_unlock(&videodev_lock);
150 /* should not happen */
155 /* Free up this device for reuse */
156 video_device[vdev->minor] = NULL;
158 /* Delete the cdev on this minor as well */
159 cdev_del(vdev->cdev);
160 /* Just in case some driver tries to access this from
161 the release() callback. */
164 /* Mark device node number as free */
167 mutex_unlock(&videodev_lock);
169 /* Release video_device and perform other
170 cleanups as needed. */
174 static struct class video_class = {
176 .dev_attrs = video_device_attrs,
179 struct video_device *video_devdata(struct file *file)
181 return video_device[iminor(file->f_path.dentry->d_inode)];
183 EXPORT_SYMBOL(video_devdata);
185 static ssize_t v4l2_read(struct file *filp, char __user *buf,
186 size_t sz, loff_t *off)
188 struct video_device *vdev = video_devdata(filp);
191 if (!vdev->fops->read)
194 mutex_lock(vdev->lock);
195 if (video_is_registered(vdev))
196 ret = vdev->fops->read(filp, buf, sz, off);
198 mutex_unlock(vdev->lock);
202 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
203 size_t sz, loff_t *off)
205 struct video_device *vdev = video_devdata(filp);
208 if (!vdev->fops->write)
211 mutex_lock(vdev->lock);
212 if (video_is_registered(vdev))
213 ret = vdev->fops->write(filp, buf, sz, off);
215 mutex_unlock(vdev->lock);
219 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
221 struct video_device *vdev = video_devdata(filp);
222 int ret = DEFAULT_POLLMASK;
224 if (!vdev->fops->poll)
227 mutex_lock(vdev->lock);
228 if (video_is_registered(vdev))
229 ret = vdev->fops->poll(filp, poll);
231 mutex_unlock(vdev->lock);
235 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
237 struct video_device *vdev = video_devdata(filp);
240 if (vdev->fops->unlocked_ioctl) {
242 mutex_lock(vdev->lock);
243 if (video_is_registered(vdev))
244 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
246 mutex_unlock(vdev->lock);
247 } else if (vdev->fops->ioctl) {
248 /* TODO: convert all drivers to unlocked_ioctl */
249 static DEFINE_MUTEX(v4l2_ioctl_mutex);
251 mutex_lock(&v4l2_ioctl_mutex);
252 if (video_is_registered(vdev))
253 ret = vdev->fops->ioctl(filp, cmd, arg);
254 mutex_unlock(&v4l2_ioctl_mutex);
261 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
263 struct video_device *vdev = video_devdata(filp);
266 if (!vdev->fops->mmap)
269 mutex_lock(vdev->lock);
270 if (video_is_registered(vdev))
271 ret = vdev->fops->mmap(filp, vm);
273 mutex_unlock(vdev->lock);
277 /* Override for the open function */
278 static int v4l2_open(struct inode *inode, struct file *filp)
280 struct video_device *vdev;
283 /* Check if the video device is available */
284 mutex_lock(&videodev_lock);
285 vdev = video_devdata(filp);
286 /* return ENODEV if the video device has already been removed. */
288 mutex_unlock(&videodev_lock);
291 /* and increase the device refcount */
293 mutex_unlock(&videodev_lock);
294 if (vdev->fops->open) {
296 mutex_lock(vdev->lock);
297 if (video_is_registered(vdev))
298 ret = vdev->fops->open(filp);
302 mutex_unlock(vdev->lock);
305 /* decrease the refcount in case of an error */
311 /* Override for the release function */
312 static int v4l2_release(struct inode *inode, struct file *filp)
314 struct video_device *vdev = video_devdata(filp);
317 if (vdev->fops->release) {
319 mutex_lock(vdev->lock);
320 vdev->fops->release(filp);
322 mutex_unlock(vdev->lock);
325 /* decrease the refcount unconditionally since the release()
326 return value is ignored. */
331 static const struct file_operations v4l2_fops = {
332 .owner = THIS_MODULE,
337 .unlocked_ioctl = v4l2_ioctl,
339 .compat_ioctl = v4l2_compat_ioctl32,
341 .release = v4l2_release,
347 * get_index - assign stream index number based on parent device
348 * @vdev: video_device to assign index number to, vdev->parent should be assigned
350 * Note that when this is called the new device has not yet been registered
351 * in the video_device array, but it was able to obtain a minor number.
353 * This means that we can always obtain a free stream index number since
354 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
355 * use of the video_device array.
357 * Returns a free index number.
359 static int get_index(struct video_device *vdev)
361 /* This can be static since this function is called with the global
362 videodev_lock held. */
363 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
366 /* Some drivers do not set the parent. In that case always return 0. */
367 if (vdev->parent == NULL)
370 bitmap_zero(used, VIDEO_NUM_DEVICES);
372 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
373 if (video_device[i] != NULL &&
374 video_device[i]->parent == vdev->parent) {
375 set_bit(video_device[i]->index, used);
379 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
383 * video_register_device - register video4linux devices
384 * @vdev: video device structure we want to register
385 * @type: type of device to register
386 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
388 * @warn_if_nr_in_use: warn if the desired device node number
389 * was already in use and another number was chosen instead.
391 * The registration code assigns minor numbers and device node numbers
392 * based on the requested type and registers the new device node with
394 * An error is returned if no free minor or device node number could be
395 * found, or if the registration of the device node failed.
397 * Zero is returned on success.
401 * %VFL_TYPE_GRABBER - A frame grabber
403 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
405 * %VFL_TYPE_RADIO - A radio card
407 static int __video_register_device(struct video_device *vdev, int type, int nr,
408 int warn_if_nr_in_use)
412 int minor_offset = 0;
413 int minor_cnt = VIDEO_NUM_DEVICES;
414 const char *name_base;
415 void *priv = vdev->dev.p;
417 /* A minor value of -1 marks this video device as never
418 having been registered */
421 /* the release callback MUST be present */
422 WARN_ON(!vdev->release);
426 /* v4l2_fh support */
427 spin_lock_init(&vdev->fh_lock);
428 INIT_LIST_HEAD(&vdev->fh_list);
430 /* Part 1: check device type */
432 case VFL_TYPE_GRABBER:
442 printk(KERN_ERR "%s called with unknown type: %d\n",
447 vdev->vfl_type = type;
449 if (vdev->v4l2_dev) {
450 if (vdev->v4l2_dev->dev)
451 vdev->parent = vdev->v4l2_dev->dev;
452 if (vdev->ctrl_handler == NULL)
453 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
456 /* Part 2: find a free minor, device node number and device index. */
457 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
458 /* Keep the ranges for the first four types for historical
460 * Newer devices (not yet in place) should use the range
461 * of 128-191 and just pick the first free minor there
464 case VFL_TYPE_GRABBER:
483 /* Pick a device node number */
484 mutex_lock(&videodev_lock);
485 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
487 nr = devnode_find(vdev, 0, minor_cnt);
488 if (nr == minor_cnt) {
489 printk(KERN_ERR "could not get a free device node number\n");
490 mutex_unlock(&videodev_lock);
493 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
494 /* 1-on-1 mapping of device node number to minor number */
497 /* The device node number and minor numbers are independent, so
498 we just find the first free minor number. */
499 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
500 if (video_device[i] == NULL)
502 if (i == VIDEO_NUM_DEVICES) {
503 mutex_unlock(&videodev_lock);
504 printk(KERN_ERR "could not get a free minor\n");
508 vdev->minor = i + minor_offset;
512 /* Should not happen since we thought this minor was free */
513 WARN_ON(video_device[vdev->minor] != NULL);
514 vdev->index = get_index(vdev);
515 mutex_unlock(&videodev_lock);
517 /* Part 3: Initialize the character device */
518 vdev->cdev = cdev_alloc();
519 if (vdev->cdev == NULL) {
523 vdev->cdev->ops = &v4l2_fops;
524 vdev->cdev->owner = vdev->fops->owner;
525 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
527 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
533 /* Part 4: register the device with sysfs */
534 memset(&vdev->dev, 0, sizeof(vdev->dev));
535 /* The memset above cleared the device's device_private, so
536 put back the copy we made earlier. */
538 vdev->dev.class = &video_class;
539 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
541 vdev->dev.parent = vdev->parent;
542 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
543 ret = device_register(&vdev->dev);
545 printk(KERN_ERR "%s: device_register failed\n", __func__);
548 /* Register the release callback that will be called when the last
549 reference to the device goes away. */
550 vdev->dev.release = v4l2_device_release;
552 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
553 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
554 name_base, nr, video_device_node_name(vdev));
556 /* Part 5: Activate this minor. The char device can now be used. */
557 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
558 mutex_lock(&videodev_lock);
559 video_device[vdev->minor] = vdev;
560 mutex_unlock(&videodev_lock);
564 mutex_lock(&videodev_lock);
566 cdev_del(vdev->cdev);
568 mutex_unlock(&videodev_lock);
569 /* Mark this video device as never having been registered. */
574 int video_register_device(struct video_device *vdev, int type, int nr)
576 return __video_register_device(vdev, type, nr, 1);
578 EXPORT_SYMBOL(video_register_device);
580 int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
582 return __video_register_device(vdev, type, nr, 0);
584 EXPORT_SYMBOL(video_register_device_no_warn);
587 * video_unregister_device - unregister a video4linux device
588 * @vdev: the device to unregister
590 * This unregisters the passed device. Future open calls will
591 * be met with errors.
593 void video_unregister_device(struct video_device *vdev)
595 /* Check if vdev was ever registered at all */
596 if (!vdev || !video_is_registered(vdev))
599 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
600 device_unregister(&vdev->dev);
602 EXPORT_SYMBOL(video_unregister_device);
605 * Initialise video for linux
607 static int __init videodev_init(void)
609 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
612 printk(KERN_INFO "Linux video capture interface: v2.00\n");
613 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
615 printk(KERN_WARNING "videodev: unable to get major %d\n",
620 ret = class_register(&video_class);
622 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
623 printk(KERN_WARNING "video_dev: class_register failed\n");
630 static void __exit videodev_exit(void)
632 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
634 class_unregister(&video_class);
635 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
638 module_init(videodev_init)
639 module_exit(videodev_exit)
641 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
642 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
643 MODULE_LICENSE("GPL");
644 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);