1 /*
2 * Video capture interface for Linux version 2
3 *
4 * A generic video device interface for the LINUX operating system
5 * using a set of device structures/vectors for low level operations.
6 *
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.
11 *
12 * Authors: Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
13 * Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
14 *
15 * Fixes: 20000516 Claudio Matsuoka <claudio@conectiva.com>
16 * - Added procfs support
17 */
18
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>
30
31 #include <media/v4l2-common.h>
32 #include <media/v4l2-device.h>
33 #include <media/v4l2-ioctl.h>
34
35 #define VIDEO_NUM_DEVICES 256
36 #define VIDEO_NAME "video4linux"
37
38 /*
39 * sysfs stuff
40 */
41
show_index(struct device * cd,struct device_attribute * attr,char * buf)42 static ssize_t show_index(struct device *cd,
43 struct device_attribute *attr, char *buf)
44 {
45 struct video_device *vdev = to_video_device(cd);
46
47 return sprintf(buf, "%i\n", vdev->index);
48 }
49
show_name(struct device * cd,struct device_attribute * attr,char * buf)50 static ssize_t show_name(struct device *cd,
51 struct device_attribute *attr, char *buf)
52 {
53 struct video_device *vdev = to_video_device(cd);
54
55 return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
56 }
57
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
62 };
63
64 /*
65 * Active devices
66 */
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);
70
71 /* Device node utility functions */
72
73 /* Note: these utility functions all assume that vfl_type is in the range
74 [0, VFL_TYPE_MAX-1]. */
75
76 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
77 /* Return the bitmap corresponding to vfl_type. */
devnode_bits(int vfl_type)78 static inline unsigned long *devnode_bits(int vfl_type)
79 {
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;
84
85 return devnode_nums[idx];
86 }
87 #else
88 /* Return the bitmap corresponding to vfl_type. */
devnode_bits(int vfl_type)89 static inline unsigned long *devnode_bits(int vfl_type)
90 {
91 return devnode_nums[vfl_type];
92 }
93 #endif
94
95 /* Mark device node number vdev->num as used */
devnode_set(struct video_device * vdev)96 static inline void devnode_set(struct video_device *vdev)
97 {
98 set_bit(vdev->num, devnode_bits(vdev->vfl_type));
99 }
100
101 /* Mark device node number vdev->num as unused */
devnode_clear(struct video_device * vdev)102 static inline void devnode_clear(struct video_device *vdev)
103 {
104 clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
105 }
106
107 /* Try to find a free device node number in the range [from, to> */
devnode_find(struct video_device * vdev,int from,int to)108 static inline int devnode_find(struct video_device *vdev, int from, int to)
109 {
110 return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
111 }
112
video_device_alloc(void)113 struct video_device *video_device_alloc(void)
114 {
115 return kzalloc(sizeof(struct video_device), GFP_KERNEL);
116 }
117 EXPORT_SYMBOL(video_device_alloc);
118
video_device_release(struct video_device * vdev)119 void video_device_release(struct video_device *vdev)
120 {
121 kfree(vdev);
122 }
123 EXPORT_SYMBOL(video_device_release);
124
video_device_release_empty(struct video_device * vdev)125 void video_device_release_empty(struct video_device *vdev)
126 {
127 /* Do nothing */
128 /* Only valid when the video_device struct is a static. */
129 }
130 EXPORT_SYMBOL(video_device_release_empty);
131
video_get(struct video_device * vdev)132 static inline void video_get(struct video_device *vdev)
133 {
134 get_device(&vdev->dev);
135 }
136
video_put(struct video_device * vdev)137 static inline void video_put(struct video_device *vdev)
138 {
139 put_device(&vdev->dev);
140 }
141
142 /* Called when the last user of the video device exits. */
v4l2_device_release(struct device * cd)143 static void v4l2_device_release(struct device *cd)
144 {
145 struct video_device *vdev = to_video_device(cd);
146 struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
147
148 mutex_lock(&videodev_lock);
149 if (WARN_ON(video_device[vdev->minor] != vdev)) {
150 /* should not happen */
151 mutex_unlock(&videodev_lock);
152 return;
153 }
154
155 /* Free up this device for reuse */
156 video_device[vdev->minor] = NULL;
157
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. */
162 vdev->cdev = NULL;
163
164 /* Mark device node number as free */
165 devnode_clear(vdev);
166
167 mutex_unlock(&videodev_lock);
168
169 #if defined(CONFIG_MEDIA_CONTROLLER)
170 if (v4l2_dev && v4l2_dev->mdev &&
171 vdev->vfl_type != VFL_TYPE_SUBDEV)
172 media_device_unregister_entity(&vdev->entity);
173 #endif
174
175 /* Do not call v4l2_device_put if there is no release callback set.
176 * Drivers that have no v4l2_device release callback might free the
177 * v4l2_dev instance in the video_device release callback below, so we
178 * must perform this check here.
179 *
180 * TODO: In the long run all drivers that use v4l2_device should use the
181 * v4l2_device release callback. This check will then be unnecessary.
182 */
183 if (v4l2_dev && v4l2_dev->release == NULL)
184 v4l2_dev = NULL;
185
186 /* Release video_device and perform other
187 cleanups as needed. */
188 vdev->release(vdev);
189
190 /* Decrease v4l2_device refcount */
191 if (v4l2_dev)
192 v4l2_device_put(v4l2_dev);
193 }
194
195 static struct class video_class = {
196 .name = VIDEO_NAME,
197 .dev_attrs = video_device_attrs,
198 };
199
video_devdata(struct file * file)200 struct video_device *video_devdata(struct file *file)
201 {
202 return video_device[iminor(file->f_path.dentry->d_inode)];
203 }
204 EXPORT_SYMBOL(video_devdata);
205
206
207 /* Priority handling */
208
prio_is_valid(enum v4l2_priority prio)209 static inline bool prio_is_valid(enum v4l2_priority prio)
210 {
211 return prio == V4L2_PRIORITY_BACKGROUND ||
212 prio == V4L2_PRIORITY_INTERACTIVE ||
213 prio == V4L2_PRIORITY_RECORD;
214 }
215
v4l2_prio_init(struct v4l2_prio_state * global)216 void v4l2_prio_init(struct v4l2_prio_state *global)
217 {
218 memset(global, 0, sizeof(*global));
219 }
220 EXPORT_SYMBOL(v4l2_prio_init);
221
v4l2_prio_change(struct v4l2_prio_state * global,enum v4l2_priority * local,enum v4l2_priority new)222 int v4l2_prio_change(struct v4l2_prio_state *global, enum v4l2_priority *local,
223 enum v4l2_priority new)
224 {
225 if (!prio_is_valid(new))
226 return -EINVAL;
227 if (*local == new)
228 return 0;
229
230 atomic_inc(&global->prios[new]);
231 if (prio_is_valid(*local))
232 atomic_dec(&global->prios[*local]);
233 *local = new;
234 return 0;
235 }
236 EXPORT_SYMBOL(v4l2_prio_change);
237
v4l2_prio_open(struct v4l2_prio_state * global,enum v4l2_priority * local)238 void v4l2_prio_open(struct v4l2_prio_state *global, enum v4l2_priority *local)
239 {
240 v4l2_prio_change(global, local, V4L2_PRIORITY_DEFAULT);
241 }
242 EXPORT_SYMBOL(v4l2_prio_open);
243
v4l2_prio_close(struct v4l2_prio_state * global,enum v4l2_priority local)244 void v4l2_prio_close(struct v4l2_prio_state *global, enum v4l2_priority local)
245 {
246 if (prio_is_valid(local))
247 atomic_dec(&global->prios[local]);
248 }
249 EXPORT_SYMBOL(v4l2_prio_close);
250
v4l2_prio_max(struct v4l2_prio_state * global)251 enum v4l2_priority v4l2_prio_max(struct v4l2_prio_state *global)
252 {
253 if (atomic_read(&global->prios[V4L2_PRIORITY_RECORD]) > 0)
254 return V4L2_PRIORITY_RECORD;
255 if (atomic_read(&global->prios[V4L2_PRIORITY_INTERACTIVE]) > 0)
256 return V4L2_PRIORITY_INTERACTIVE;
257 if (atomic_read(&global->prios[V4L2_PRIORITY_BACKGROUND]) > 0)
258 return V4L2_PRIORITY_BACKGROUND;
259 return V4L2_PRIORITY_UNSET;
260 }
261 EXPORT_SYMBOL(v4l2_prio_max);
262
v4l2_prio_check(struct v4l2_prio_state * global,enum v4l2_priority local)263 int v4l2_prio_check(struct v4l2_prio_state *global, enum v4l2_priority local)
264 {
265 return (local < v4l2_prio_max(global)) ? -EBUSY : 0;
266 }
267 EXPORT_SYMBOL(v4l2_prio_check);
268
269
v4l2_read(struct file * filp,char __user * buf,size_t sz,loff_t * off)270 static ssize_t v4l2_read(struct file *filp, char __user *buf,
271 size_t sz, loff_t *off)
272 {
273 struct video_device *vdev = video_devdata(filp);
274 int ret = -ENODEV;
275
276 if (!vdev->fops->read)
277 return -EINVAL;
278 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
279 return -ERESTARTSYS;
280 if (video_is_registered(vdev))
281 ret = vdev->fops->read(filp, buf, sz, off);
282 if (vdev->lock)
283 mutex_unlock(vdev->lock);
284 return ret;
285 }
286
v4l2_write(struct file * filp,const char __user * buf,size_t sz,loff_t * off)287 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
288 size_t sz, loff_t *off)
289 {
290 struct video_device *vdev = video_devdata(filp);
291 int ret = -ENODEV;
292
293 if (!vdev->fops->write)
294 return -EINVAL;
295 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
296 return -ERESTARTSYS;
297 if (video_is_registered(vdev))
298 ret = vdev->fops->write(filp, buf, sz, off);
299 if (vdev->lock)
300 mutex_unlock(vdev->lock);
301 return ret;
302 }
303
v4l2_poll(struct file * filp,struct poll_table_struct * poll)304 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
305 {
306 struct video_device *vdev = video_devdata(filp);
307 int ret = POLLERR | POLLHUP;
308
309 if (!vdev->fops->poll)
310 return DEFAULT_POLLMASK;
311 if (vdev->lock)
312 mutex_lock(vdev->lock);
313 if (video_is_registered(vdev))
314 ret = vdev->fops->poll(filp, poll);
315 if (vdev->lock)
316 mutex_unlock(vdev->lock);
317 return ret;
318 }
319
v4l2_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)320 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
321 {
322 struct video_device *vdev = video_devdata(filp);
323 int ret = -ENODEV;
324
325 if (vdev->fops->unlocked_ioctl) {
326 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
327 return -ERESTARTSYS;
328 if (video_is_registered(vdev))
329 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
330 if (vdev->lock)
331 mutex_unlock(vdev->lock);
332 } else if (vdev->fops->ioctl) {
333 /* This code path is a replacement for the BKL. It is a major
334 * hack but it will have to do for those drivers that are not
335 * yet converted to use unlocked_ioctl.
336 *
337 * There are two options: if the driver implements struct
338 * v4l2_device, then the lock defined there is used to
339 * serialize the ioctls. Otherwise the v4l2 core lock defined
340 * below is used. This lock is really bad since it serializes
341 * completely independent devices.
342 *
343 * Both variants suffer from the same problem: if the driver
344 * sleeps, then it blocks all ioctls since the lock is still
345 * held. This is very common for VIDIOC_DQBUF since that
346 * normally waits for a frame to arrive. As a result any other
347 * ioctl calls will proceed very, very slowly since each call
348 * will have to wait for the VIDIOC_QBUF to finish. Things that
349 * should take 0.01s may now take 10-20 seconds.
350 *
351 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
352 * This actually works OK for videobuf-based drivers, since
353 * videobuf will take its own internal lock.
354 */
355 static DEFINE_MUTEX(v4l2_ioctl_mutex);
356 struct mutex *m = vdev->v4l2_dev ?
357 &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
358
359 if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
360 return -ERESTARTSYS;
361 if (video_is_registered(vdev))
362 ret = vdev->fops->ioctl(filp, cmd, arg);
363 if (cmd != VIDIOC_DQBUF)
364 mutex_unlock(m);
365 } else
366 ret = -ENOTTY;
367
368 return ret;
369 }
370
371 #ifdef CONFIG_MMU
372 #define v4l2_get_unmapped_area NULL
373 #else
v4l2_get_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)374 static unsigned long v4l2_get_unmapped_area(struct file *filp,
375 unsigned long addr, unsigned long len, unsigned long pgoff,
376 unsigned long flags)
377 {
378 struct video_device *vdev = video_devdata(filp);
379
380 if (!vdev->fops->get_unmapped_area)
381 return -ENOSYS;
382 if (!video_is_registered(vdev))
383 return -ENODEV;
384 return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
385 }
386 #endif
387
v4l2_mmap(struct file * filp,struct vm_area_struct * vm)388 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
389 {
390 struct video_device *vdev = video_devdata(filp);
391 int ret = -ENODEV;
392
393 if (!vdev->fops->mmap)
394 return ret;
395 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
396 return -ERESTARTSYS;
397 if (video_is_registered(vdev))
398 ret = vdev->fops->mmap(filp, vm);
399 if (vdev->lock)
400 mutex_unlock(vdev->lock);
401 return ret;
402 }
403
404 /* Override for the open function */
v4l2_open(struct inode * inode,struct file * filp)405 static int v4l2_open(struct inode *inode, struct file *filp)
406 {
407 struct video_device *vdev;
408 int ret = 0;
409
410 /* Check if the video device is available */
411 mutex_lock(&videodev_lock);
412 vdev = video_devdata(filp);
413 /* return ENODEV if the video device has already been removed. */
414 if (vdev == NULL || !video_is_registered(vdev)) {
415 mutex_unlock(&videodev_lock);
416 return -ENODEV;
417 }
418 /* and increase the device refcount */
419 video_get(vdev);
420 mutex_unlock(&videodev_lock);
421 if (vdev->fops->open) {
422 if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
423 ret = -ERESTARTSYS;
424 goto err;
425 }
426 if (video_is_registered(vdev))
427 ret = vdev->fops->open(filp);
428 else
429 ret = -ENODEV;
430 if (vdev->lock)
431 mutex_unlock(vdev->lock);
432 }
433
434 err:
435 /* decrease the refcount in case of an error */
436 if (ret)
437 video_put(vdev);
438 return ret;
439 }
440
441 /* Override for the release function */
v4l2_release(struct inode * inode,struct file * filp)442 static int v4l2_release(struct inode *inode, struct file *filp)
443 {
444 struct video_device *vdev = video_devdata(filp);
445 int ret = 0;
446
447 if (vdev->fops->release) {
448 if (vdev->lock)
449 mutex_lock(vdev->lock);
450 vdev->fops->release(filp);
451 if (vdev->lock)
452 mutex_unlock(vdev->lock);
453 }
454 /* decrease the refcount unconditionally since the release()
455 return value is ignored. */
456 video_put(vdev);
457 return ret;
458 }
459
460 static const struct file_operations v4l2_fops = {
461 .owner = THIS_MODULE,
462 .read = v4l2_read,
463 .write = v4l2_write,
464 .open = v4l2_open,
465 .get_unmapped_area = v4l2_get_unmapped_area,
466 .mmap = v4l2_mmap,
467 .unlocked_ioctl = v4l2_ioctl,
468 #ifdef CONFIG_COMPAT
469 .compat_ioctl = v4l2_compat_ioctl32,
470 #endif
471 .release = v4l2_release,
472 .poll = v4l2_poll,
473 .llseek = no_llseek,
474 };
475
476 /**
477 * get_index - assign stream index number based on parent device
478 * @vdev: video_device to assign index number to, vdev->parent should be assigned
479 *
480 * Note that when this is called the new device has not yet been registered
481 * in the video_device array, but it was able to obtain a minor number.
482 *
483 * This means that we can always obtain a free stream index number since
484 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
485 * use of the video_device array.
486 *
487 * Returns a free index number.
488 */
get_index(struct video_device * vdev)489 static int get_index(struct video_device *vdev)
490 {
491 /* This can be static since this function is called with the global
492 videodev_lock held. */
493 static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
494 int i;
495
496 /* Some drivers do not set the parent. In that case always return 0. */
497 if (vdev->parent == NULL)
498 return 0;
499
500 bitmap_zero(used, VIDEO_NUM_DEVICES);
501
502 for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
503 if (video_device[i] != NULL &&
504 video_device[i]->parent == vdev->parent) {
505 set_bit(video_device[i]->index, used);
506 }
507 }
508
509 return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
510 }
511
512 /**
513 * __video_register_device - register video4linux devices
514 * @vdev: video device structure we want to register
515 * @type: type of device to register
516 * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
517 * -1 == first free)
518 * @warn_if_nr_in_use: warn if the desired device node number
519 * was already in use and another number was chosen instead.
520 * @owner: module that owns the video device node
521 *
522 * The registration code assigns minor numbers and device node numbers
523 * based on the requested type and registers the new device node with
524 * the kernel.
525 *
526 * This function assumes that struct video_device was zeroed when it
527 * was allocated and does not contain any stale date.
528 *
529 * An error is returned if no free minor or device node number could be
530 * found, or if the registration of the device node failed.
531 *
532 * Zero is returned on success.
533 *
534 * Valid types are
535 *
536 * %VFL_TYPE_GRABBER - A frame grabber
537 *
538 * %VFL_TYPE_VBI - Vertical blank data (undecoded)
539 *
540 * %VFL_TYPE_RADIO - A radio card
541 *
542 * %VFL_TYPE_SUBDEV - A subdevice
543 */
__video_register_device(struct video_device * vdev,int type,int nr,int warn_if_nr_in_use,struct module * owner)544 int __video_register_device(struct video_device *vdev, int type, int nr,
545 int warn_if_nr_in_use, struct module *owner)
546 {
547 int i = 0;
548 int ret;
549 int minor_offset = 0;
550 int minor_cnt = VIDEO_NUM_DEVICES;
551 const char *name_base;
552
553 /* A minor value of -1 marks this video device as never
554 having been registered */
555 vdev->minor = -1;
556
557 /* the release callback MUST be present */
558 if (WARN_ON(!vdev->release))
559 return -EINVAL;
560
561 /* v4l2_fh support */
562 spin_lock_init(&vdev->fh_lock);
563 INIT_LIST_HEAD(&vdev->fh_list);
564
565 /* Part 1: check device type */
566 switch (type) {
567 case VFL_TYPE_GRABBER:
568 name_base = "video";
569 break;
570 case VFL_TYPE_VBI:
571 name_base = "vbi";
572 break;
573 case VFL_TYPE_RADIO:
574 name_base = "radio";
575 break;
576 case VFL_TYPE_SUBDEV:
577 name_base = "v4l-subdev";
578 break;
579 default:
580 printk(KERN_ERR "%s called with unknown type: %d\n",
581 __func__, type);
582 return -EINVAL;
583 }
584
585 vdev->vfl_type = type;
586 vdev->cdev = NULL;
587 if (vdev->v4l2_dev) {
588 if (vdev->v4l2_dev->dev)
589 vdev->parent = vdev->v4l2_dev->dev;
590 if (vdev->ctrl_handler == NULL)
591 vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
592 /* If the prio state pointer is NULL, then use the v4l2_device
593 prio state. */
594 if (vdev->prio == NULL)
595 vdev->prio = &vdev->v4l2_dev->prio;
596 }
597
598 /* Part 2: find a free minor, device node number and device index. */
599 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
600 /* Keep the ranges for the first four types for historical
601 * reasons.
602 * Newer devices (not yet in place) should use the range
603 * of 128-191 and just pick the first free minor there
604 * (new style). */
605 switch (type) {
606 case VFL_TYPE_GRABBER:
607 minor_offset = 0;
608 minor_cnt = 64;
609 break;
610 case VFL_TYPE_RADIO:
611 minor_offset = 64;
612 minor_cnt = 64;
613 break;
614 case VFL_TYPE_VBI:
615 minor_offset = 224;
616 minor_cnt = 32;
617 break;
618 default:
619 minor_offset = 128;
620 minor_cnt = 64;
621 break;
622 }
623 #endif
624
625 /* Pick a device node number */
626 mutex_lock(&videodev_lock);
627 nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
628 if (nr == minor_cnt)
629 nr = devnode_find(vdev, 0, minor_cnt);
630 if (nr == minor_cnt) {
631 printk(KERN_ERR "could not get a free device node number\n");
632 mutex_unlock(&videodev_lock);
633 return -ENFILE;
634 }
635 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
636 /* 1-on-1 mapping of device node number to minor number */
637 i = nr;
638 #else
639 /* The device node number and minor numbers are independent, so
640 we just find the first free minor number. */
641 for (i = 0; i < VIDEO_NUM_DEVICES; i++)
642 if (video_device[i] == NULL)
643 break;
644 if (i == VIDEO_NUM_DEVICES) {
645 mutex_unlock(&videodev_lock);
646 printk(KERN_ERR "could not get a free minor\n");
647 return -ENFILE;
648 }
649 #endif
650 vdev->minor = i + minor_offset;
651 vdev->num = nr;
652 devnode_set(vdev);
653
654 /* Should not happen since we thought this minor was free */
655 WARN_ON(video_device[vdev->minor] != NULL);
656 vdev->index = get_index(vdev);
657 mutex_unlock(&videodev_lock);
658
659 /* Part 3: Initialize the character device */
660 vdev->cdev = cdev_alloc();
661 if (vdev->cdev == NULL) {
662 ret = -ENOMEM;
663 goto cleanup;
664 }
665 vdev->cdev->ops = &v4l2_fops;
666 vdev->cdev->owner = owner;
667 ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
668 if (ret < 0) {
669 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
670 kfree(vdev->cdev);
671 vdev->cdev = NULL;
672 goto cleanup;
673 }
674
675 /* Part 4: register the device with sysfs */
676 vdev->dev.class = &video_class;
677 vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
678 if (vdev->parent)
679 vdev->dev.parent = vdev->parent;
680 dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
681 ret = device_register(&vdev->dev);
682 if (ret < 0) {
683 printk(KERN_ERR "%s: device_register failed\n", __func__);
684 goto cleanup;
685 }
686 /* Register the release callback that will be called when the last
687 reference to the device goes away. */
688 vdev->dev.release = v4l2_device_release;
689
690 if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
691 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
692 name_base, nr, video_device_node_name(vdev));
693
694 /* Increase v4l2_device refcount */
695 if (vdev->v4l2_dev)
696 v4l2_device_get(vdev->v4l2_dev);
697
698 #if defined(CONFIG_MEDIA_CONTROLLER)
699 /* Part 5: Register the entity. */
700 if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
701 vdev->vfl_type != VFL_TYPE_SUBDEV) {
702 vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
703 vdev->entity.name = vdev->name;
704 vdev->entity.info.v4l.major = VIDEO_MAJOR;
705 vdev->entity.info.v4l.minor = vdev->minor;
706 ret = media_device_register_entity(vdev->v4l2_dev->mdev,
707 &vdev->entity);
708 if (ret < 0)
709 printk(KERN_WARNING
710 "%s: media_device_register_entity failed\n",
711 __func__);
712 }
713 #endif
714 /* Part 6: Activate this minor. The char device can now be used. */
715 set_bit(V4L2_FL_REGISTERED, &vdev->flags);
716 mutex_lock(&videodev_lock);
717 video_device[vdev->minor] = vdev;
718 mutex_unlock(&videodev_lock);
719
720 return 0;
721
722 cleanup:
723 mutex_lock(&videodev_lock);
724 if (vdev->cdev)
725 cdev_del(vdev->cdev);
726 devnode_clear(vdev);
727 mutex_unlock(&videodev_lock);
728 /* Mark this video device as never having been registered. */
729 vdev->minor = -1;
730 return ret;
731 }
732 EXPORT_SYMBOL(__video_register_device);
733
734 /**
735 * video_unregister_device - unregister a video4linux device
736 * @vdev: the device to unregister
737 *
738 * This unregisters the passed device. Future open calls will
739 * be met with errors.
740 */
video_unregister_device(struct video_device * vdev)741 void video_unregister_device(struct video_device *vdev)
742 {
743 /* Check if vdev was ever registered at all */
744 if (!vdev || !video_is_registered(vdev))
745 return;
746
747 mutex_lock(&videodev_lock);
748 /* This must be in a critical section to prevent a race with v4l2_open.
749 * Once this bit has been cleared video_get may never be called again.
750 */
751 clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
752 mutex_unlock(&videodev_lock);
753 device_unregister(&vdev->dev);
754 }
755 EXPORT_SYMBOL(video_unregister_device);
756
757 /*
758 * Initialise video for linux
759 */
videodev_init(void)760 static int __init videodev_init(void)
761 {
762 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
763 int ret;
764
765 printk(KERN_INFO "Linux video capture interface: v2.00\n");
766 ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
767 if (ret < 0) {
768 printk(KERN_WARNING "videodev: unable to get major %d\n",
769 VIDEO_MAJOR);
770 return ret;
771 }
772
773 ret = class_register(&video_class);
774 if (ret < 0) {
775 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
776 printk(KERN_WARNING "video_dev: class_register failed\n");
777 return -EIO;
778 }
779
780 return 0;
781 }
782
videodev_exit(void)783 static void __exit videodev_exit(void)
784 {
785 dev_t dev = MKDEV(VIDEO_MAJOR, 0);
786
787 class_unregister(&video_class);
788 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
789 }
790
791 module_init(videodev_init)
792 module_exit(videodev_exit)
793
794 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
795 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
796 MODULE_LICENSE("GPL");
797 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);
798
799
800 /*
801 * Local variables:
802 * c-basic-offset: 8
803 * End:
804 */
805