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 <linux/smp_lock.h>
29 #include <asm/uaccess.h>
30 #include <asm/system.h>
32 #include <media/v4l2-common.h>
33 #include <media/v4l2-device.h>
34 #include <media/v4l2-ioctl.h>
36 #define VIDEO_NUM_DEVICES 256
37 #define VIDEO_NAME "video4linux"
43 static ssize_t show_index(struct device *cd,
44 struct device_attribute *attr, char *buf)
46 struct video_device *vdev = to_video_device(cd);
48 return sprintf(buf, "%i\n", vdev->index);
51 static ssize_t show_name(struct device *cd,
52 struct device_attribute *attr, char *buf)
54 struct video_device *vdev = to_video_device(cd);
56 return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
59 static struct device_attribute video_device_attrs[] = {
60 __ATTR(name, S_IRUGO, show_name, NULL),
61 __ATTR(index, S_IRUGO, show_index, NULL),
68 static struct video_device *video_device[VIDEO_NUM_DEVICES];
69 static DEFINE_MUTEX(videodev_lock);
70 static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
72 /* Device node utility functions */
74 /* Note: these utility functions all assume that vfl_type is in the range
75 [0, VFL_TYPE_MAX-1]. */
77 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
78 /* Return the bitmap corresponding to vfl_type. */
79 static inline unsigned long *devnode_bits(int vfl_type)
81 /* Any types not assigned to fixed minor ranges must be mapped to
82 one single bitmap for the purposes of finding a free node number
83 since all those unassigned types use the same minor range. */
84 int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;
86 return devnode_nums[idx];
89 /* Return the bitmap corresponding to vfl_type. */
90 static inline unsigned long *devnode_bits(int vfl_type)
92 return devnode_nums[vfl_type];
96 /* Mark device node number vdev->num as used */
97 static inline void devnode_set(struct video_device *vdev)
99 set_bit(vdev->num, devnode_bits(vdev->vfl_type));
102 /* Mark device node number vdev->num as unused */
103 static inline void devnode_clear(struct video_device *vdev)
105 clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
108 /* Try to find a free device node number in the range [from, to> */
109 static inline int devnode_find(struct video_device *vdev, int from, int to)
111 return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
114 struct video_device *video_device_alloc(void)
116 return kzalloc(sizeof(struct video_device), GFP_KERNEL);
118 EXPORT_SYMBOL(video_device_alloc);
120 void video_device_release(struct video_device *vdev)
124 EXPORT_SYMBOL(video_device_release);
126 void video_device_release_empty(struct video_device *vdev)
129 /* Only valid when the video_device struct is a static. */
131 EXPORT_SYMBOL(video_device_release_empty);
133 static inline void video_get(struct video_device *vdev)
135 get_device(&vdev->dev);
138 static inline void video_put(struct video_device *vdev)
140 put_device(&vdev->dev);
143 /* Called when the last user of the video device exits. */
144 static void v4l2_device_release(struct device *cd)
146 struct video_device *vdev = to_video_device(cd);
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 /* Release video_device and perform other
171 cleanups as needed. */
175 static struct class video_class = {
177 .dev_attrs = video_device_attrs,
180 struct video_device *video_devdata(struct file *file)
182 return video_device[iminor(file->f_path.dentry->d_inode)];
184 EXPORT_SYMBOL(video_devdata);
186 static ssize_t v4l2_read(struct file *filp, char __user *buf,
187 size_t sz, loff_t *off)
189 struct video_device *vdev = video_devdata(filp);
192 if (!vdev->fops->read)
195 mutex_lock(vdev->lock);
196 if (video_is_registered(vdev))
197 ret = vdev->fops->read(filp, buf, sz, off);
199 mutex_unlock(vdev->lock);
203 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
204 size_t sz, loff_t *off)
206 struct video_device *vdev = video_devdata(filp);
209 if (!vdev->fops->write)
212 mutex_lock(vdev->lock);
213 if (video_is_registered(vdev))
214 ret = vdev->fops->write(filp, buf, sz, off);
216 mutex_unlock(vdev->lock);
220 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
222 struct video_device *vdev = video_devdata(filp);
223 int ret = DEFAULT_POLLMASK;
225 if (!vdev->fops->poll)
228 mutex_lock(vdev->lock);
229 if (video_is_registered(vdev))
230 ret = vdev->fops->poll(filp, poll);
232 mutex_unlock(vdev->lock);
236 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
238 struct video_device *vdev = video_devdata(filp);
241 if (vdev->fops->unlocked_ioctl) {
243 mutex_lock(vdev->lock);
244 if (video_is_registered(vdev))
245 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
247 mutex_unlock(vdev->lock);
248 } else if (vdev->fops->ioctl) {
249 /* TODO: convert all drivers to unlocked_ioctl */
251 if (video_is_registered(vdev))
252 ret = vdev->fops->ioctl(filp, cmd, arg);
260 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
262 struct video_device *vdev = video_devdata(filp);
265 if (!vdev->fops->mmap)
268 mutex_lock(vdev->lock);
269 if (video_is_registered(vdev))
270 ret = vdev->fops->mmap(filp, vm);
272 mutex_unlock(vdev->lock);
276 /* Override for the open function */
277 static int v4l2_open(struct inode *inode, struct file *filp)
279 struct video_device *vdev;
282 /* Check if the video device is available */
283 mutex_lock(&videodev_lock);
284 vdev = video_devdata(filp);
285 /* return ENODEV if the video device has already been removed. */
287 mutex_unlock(&videodev_lock);
290 /* and increase the device refcount */
292 mutex_unlock(&videodev_lock);
293 if (vdev->fops->open) {
295 mutex_lock(vdev->lock);
296 if (video_is_registered(vdev))
297 ret = vdev->fops->open(filp);
301 mutex_unlock(vdev->lock);
304 /* decrease the refcount in case of an error */
310 /* Override for the release function */
311 static int v4l2_release(struct inode *inode, struct file *filp)
313 struct video_device *vdev = video_devdata(filp);
316 if (vdev->fops->release) {
318 mutex_lock(vdev->lock);
319 vdev->fops->release(filp);
321 mutex_unlock(vdev->lock);
324 /* decrease the refcount unconditionally since the release()
325 return value is ignored. */
330 static const struct file_operations v4l2_fops = {
331 .owner = THIS_MODULE,
336 .unlocked_ioctl = v4l2_ioctl,
338 .compat_ioctl = v4l2_compat_ioctl32,
340 .release = v4l2_release,
346 * get_index - assign stream index number based on parent device
347 * @vdev: video_device to assign index number to, vdev->parent should be assigned
349 * Note that when this is called the new device has not yet been registered
350 * in the video_device array, but it was able to obtain a minor number.
352 * This means that we can always obtain a free stream index number since
353 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
354 * use of the video_device array.
356 * Returns a free index number.
358 static int get_index(struct video_device *vdev)
360 /* This can be static since this function is called with the global
361 videodev_lock held. */
362 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
365 /* Some drivers do not set the parent. In that case always return 0. */
366 if (vdev->parent == NULL)
369 bitmap_zero(used, VIDEO_NUM_DEVICES);
371 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
372 if (video_device[i] != NULL &&
373 video_device[i]->parent == vdev->parent) {
374 set_bit(video_device[i]->index, used);
378 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
382 * video_register_device - register video4linux devices
383 * @vdev: video device structure we want to register
384 * @type: type of device to register
385 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
387 * @warn_if_nr_in_use: warn if the desired device node number
388 * was already in use and another number was chosen instead.
390 * The registration code assigns minor numbers and device node numbers
391 * based on the requested type and registers the new device node with
393 * An error is returned if no free minor or device node number could be
394 * found, or if the registration of the device node failed.
396 * Zero is returned on success.
400 * %VFL_TYPE_GRABBER - A frame grabber
402 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
404 * %VFL_TYPE_RADIO - A radio card
406 static int __video_register_device(struct video_device *vdev, int type, int nr,
407 int warn_if_nr_in_use)
411 int minor_offset = 0;
412 int minor_cnt = VIDEO_NUM_DEVICES;
413 const char *name_base;
414 void *priv = vdev->dev.p;
416 /* A minor value of -1 marks this video device as never
417 having been registered */
420 /* the release callback MUST be present */
421 WARN_ON(!vdev->release);
425 /* v4l2_fh support */
426 spin_lock_init(&vdev->fh_lock);
427 INIT_LIST_HEAD(&vdev->fh_list);
429 /* Part 1: check device type */
431 case VFL_TYPE_GRABBER:
441 printk(KERN_ERR "%s called with unknown type: %d\n",
446 vdev->vfl_type = type;
448 if (vdev->v4l2_dev) {
449 if (vdev->v4l2_dev->dev)
450 vdev->parent = vdev->v4l2_dev->dev;
451 if (vdev->ctrl_handler == NULL)
452 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
455 /* Part 2: find a free minor, device node number and device index. */
456 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
457 /* Keep the ranges for the first four types for historical
459 * Newer devices (not yet in place) should use the range
460 * of 128-191 and just pick the first free minor there
463 case VFL_TYPE_GRABBER:
482 /* Pick a device node number */
483 mutex_lock(&videodev_lock);
484 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
486 nr = devnode_find(vdev, 0, minor_cnt);
487 if (nr == minor_cnt) {
488 printk(KERN_ERR "could not get a free device node number\n");
489 mutex_unlock(&videodev_lock);
492 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
493 /* 1-on-1 mapping of device node number to minor number */
496 /* The device node number and minor numbers are independent, so
497 we just find the first free minor number. */
498 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
499 if (video_device[i] == NULL)
501 if (i == VIDEO_NUM_DEVICES) {
502 mutex_unlock(&videodev_lock);
503 printk(KERN_ERR "could not get a free minor\n");
507 vdev->minor = i + minor_offset;
511 /* Should not happen since we thought this minor was free */
512 WARN_ON(video_device[vdev->minor] != NULL);
513 vdev->index = get_index(vdev);
514 mutex_unlock(&videodev_lock);
516 /* Part 3: Initialize the character device */
517 vdev->cdev = cdev_alloc();
518 if (vdev->cdev == NULL) {
522 vdev->cdev->ops = &v4l2_fops;
523 vdev->cdev->owner = vdev->fops->owner;
524 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
526 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
532 /* Part 4: register the device with sysfs */
533 memset(&vdev->dev, 0, sizeof(vdev->dev));
534 /* The memset above cleared the device's device_private, so
535 put back the copy we made earlier. */
537 vdev->dev.class = &video_class;
538 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
540 vdev->dev.parent = vdev->parent;
541 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
542 ret = device_register(&vdev->dev);
544 printk(KERN_ERR "%s: device_register failed\n", __func__);
547 /* Register the release callback that will be called when the last
548 reference to the device goes away. */
549 vdev->dev.release = v4l2_device_release;
551 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
552 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
553 name_base, nr, video_device_node_name(vdev));
555 /* Part 5: Activate this minor. The char device can now be used. */
556 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
557 mutex_lock(&videodev_lock);
558 video_device[vdev->minor] = vdev;
559 mutex_unlock(&videodev_lock);
563 mutex_lock(&videodev_lock);
565 cdev_del(vdev->cdev);
567 mutex_unlock(&videodev_lock);
568 /* Mark this video device as never having been registered. */
573 int video_register_device(struct video_device *vdev, int type, int nr)
575 return __video_register_device(vdev, type, nr, 1);
577 EXPORT_SYMBOL(video_register_device);
579 int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
581 return __video_register_device(vdev, type, nr, 0);
583 EXPORT_SYMBOL(video_register_device_no_warn);
586 * video_unregister_device - unregister a video4linux device
587 * @vdev: the device to unregister
589 * This unregisters the passed device. Future open calls will
590 * be met with errors.
592 void video_unregister_device(struct video_device *vdev)
594 /* Check if vdev was ever registered at all */
595 if (!vdev || !video_is_registered(vdev))
598 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
599 device_unregister(&vdev->dev);
601 EXPORT_SYMBOL(video_unregister_device);
604 * Initialise video for linux
606 static int __init videodev_init(void)
608 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
611 printk(KERN_INFO "Linux video capture interface: v2.00\n");
612 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
614 printk(KERN_WARNING "videodev: unable to get major %d\n",
619 ret = class_register(&video_class);
621 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
622 printk(KERN_WARNING "video_dev: class_register failed\n");
629 static void __exit videodev_exit(void)
631 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
633 class_unregister(&video_class);
634 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
637 module_init(videodev_init)
638 module_exit(videodev_exit)
640 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
641 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
642 MODULE_LICENSE("GPL");
643 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);