drivers/media/video/v4l2-dev.c

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