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 static ssize_t v4l2_read(struct file *filp, char __user *buf,
 186                 size_t sz, loff_t *off)
 187 {
 188         struct video_device *vdev = video_devdata(filp);
 189         int ret = -ENODEV;
 190
 191         if (!vdev->fops->read)
 192                 return -EINVAL;
 193         if (vdev->lock && mutex_lock_interruptible(vdev->lock))
 194                 return -ERESTARTSYS;
 195         if (video_is_registered(vdev))
 196                 ret = vdev->fops->read(filp, buf, sz, off);
 197         if (vdev->lock)
 198                 mutex_unlock(vdev->lock);
 199         return ret;
 200 }
 201
 202 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
 203                 size_t sz, loff_t *off)
 204 {
 205         struct video_device *vdev = video_devdata(filp);
 206         int ret = -ENODEV;
 207
 208         if (!vdev->fops->write)
 209                 return -EINVAL;
 210         if (vdev->lock && mutex_lock_interruptible(vdev->lock))
 211                 return -ERESTARTSYS;
 212         if (video_is_registered(vdev))
 213                 ret = vdev->fops->write(filp, buf, sz, off);
 214         if (vdev->lock)
 215                 mutex_unlock(vdev->lock);
 216         return ret;
 217 }
 218
 219 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
 220 {
 221         struct video_device *vdev = video_devdata(filp);
 222         int ret = POLLERR | POLLHUP;
 223
 224         if (!vdev->fops->poll)
 225                 return DEFAULT_POLLMASK;
 226         if (vdev->lock)
 227                 mutex_lock(vdev->lock);
 228         if (video_is_registered(vdev))
 229                 ret = vdev->fops->poll(filp, poll);
 230         if (vdev->lock)
 231                 mutex_unlock(vdev->lock);
 232         return ret;
 233 }
 234
 235 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 236 {
 237         struct video_device *vdev = video_devdata(filp);
 238         int ret = -ENODEV;
 239
 240         if (vdev->fops->unlocked_ioctl) {
 241                 if (vdev->lock && mutex_lock_interruptible(vdev->lock))
 242                         return -ERESTARTSYS;
 243                 if (video_is_registered(vdev))
 244                         ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
 245                 if (vdev->lock)
 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);
 250
 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);
 255         } else
 256                 ret = -ENOTTY;
 257
 258         return ret;
 259 }
 260
 261 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
 262 {
 263         struct video_device *vdev = video_devdata(filp);
 264         int ret = -ENODEV;
 265
 266         if (!vdev->fops->mmap)
 267                 return ret;
 268         if (vdev->lock && mutex_lock_interruptible(vdev->lock))
 269                 return -ERESTARTSYS;
 270         if (video_is_registered(vdev))
 271                 ret = vdev->fops->mmap(filp, vm);
 272         if (vdev->lock)
 273                 mutex_unlock(vdev->lock);
 274         return ret;
 275 }
 276
 277 /* Override for the open function */
 278 static int v4l2_open(struct inode *inode, struct file *filp)
 279 {
 280         struct video_device *vdev;
 281         int ret = 0;
 282
 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. */
 287         if (vdev == NULL) {
 288                 mutex_unlock(&videodev_lock);
 289                 return -ENODEV;
 290         }
 291         /* and increase the device refcount */
 292         video_get(vdev);
 293         mutex_unlock(&videodev_lock);
 294         if (vdev->fops->open) {
 295                 if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
 296                         ret = -ERESTARTSYS;
 297                         goto err;
 298                 }
 299                 if (video_is_registered(vdev))
 300                         ret = vdev->fops->open(filp);
 301                 else
 302                         ret = -ENODEV;
 303                 if (vdev->lock)
 304                         mutex_unlock(vdev->lock);
 305         }
 306
 307 err:
 308         /* decrease the refcount in case of an error */
 309         if (ret)
 310                 video_put(vdev);
 311         return ret;
 312 }
 313
 314 /* Override for the release function */
 315 static int v4l2_release(struct inode *inode, struct file *filp)
 316 {
 317         struct video_device *vdev = video_devdata(filp);
 318         int ret = 0;
 319
 320         if (vdev->fops->release) {
 321                 if (vdev->lock)
 322                         mutex_lock(vdev->lock);
 323                 vdev->fops->release(filp);
 324                 if (vdev->lock)
 325                         mutex_unlock(vdev->lock);
 326         }
 327
 328         /* decrease the refcount unconditionally since the release()
 329            return value is ignored. */
 330         video_put(vdev);
 331         return ret;
 332 }
 333
 334 static const struct file_operations v4l2_fops = {
 335         .owner = THIS_MODULE,
 336         .read = v4l2_read,
 337         .write = v4l2_write,
 338         .open = v4l2_open,
 339         .mmap = v4l2_mmap,
 340         .unlocked_ioctl = v4l2_ioctl,
 341 #ifdef CONFIG_COMPAT
 342         .compat_ioctl = v4l2_compat_ioctl32,
 343 #endif
 344         .release = v4l2_release,
 345         .poll = v4l2_poll,
 346         .llseek = no_llseek,
 347 };
 348
 349 /**
 350  * get_index - assign stream index number based on parent device
 351  * @vdev: video_device to assign index number to, vdev->parent should be assigned
 352  *
 353  * Note that when this is called the new device has not yet been registered
 354  * in the video_device array, but it was able to obtain a minor number.
 355  *
 356  * This means that we can always obtain a free stream index number since
 357  * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
 358  * use of the video_device array.
 359  *
 360  * Returns a free index number.
 361  */
 362 static int get_index(struct video_device *vdev)
 363 {
 364         /* This can be static since this function is called with the global
 365            videodev_lock held. */
 366         static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
 367         int i;
 368
 369         /* Some drivers do not set the parent. In that case always return 0. */
 370         if (vdev->parent == NULL)
 371                 return 0;
 372
 373         bitmap_zero(used, VIDEO_NUM_DEVICES);
 374
 375         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 376                 if (video_device[i] != NULL &&
 377                     video_device[i]->parent == vdev->parent) {
 378                         set_bit(video_device[i]->index, used);
 379                 }
 380         }
 381
 382         return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
 383 }
 384
 385 /**
 386  *      video_register_device - register video4linux devices
 387  *      @vdev: video device structure we want to register
 388  *      @type: type of device to register
 389  *      @nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...
 390  *             -1 == first free)
 391  *      @warn_if_nr_in_use: warn if the desired device node number
 392  *             was already in use and another number was chosen instead.
 393  *
 394  *      The registration code assigns minor numbers and device node numbers
 395  *      based on the requested type and registers the new device node with
 396  *      the kernel.
 397  *      An error is returned if no free minor or device node number could be
 398  *      found, or if the registration of the device node failed.
 399  *
 400  *      Zero is returned on success.
 401  *
 402  *      Valid types are
 403  *
 404  *      %VFL_TYPE_GRABBER - A frame grabber
 405  *
 406  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 407  *
 408  *      %VFL_TYPE_RADIO - A radio card
 409  */
 410 static int __video_register_device(struct video_device *vdev, int type, int nr,
 411                 int warn_if_nr_in_use)
 412 {
 413         int i = 0;
 414         int ret;
 415         int minor_offset = 0;
 416         int minor_cnt = VIDEO_NUM_DEVICES;
 417         const char *name_base;
 418         void *priv = vdev->dev.p;
 419
 420         /* A minor value of -1 marks this video device as never
 421            having been registered */
 422         vdev->minor = -1;
 423
 424         /* the release callback MUST be present */
 425         WARN_ON(!vdev->release);
 426         if (!vdev->release)
 427                 return -EINVAL;
 428
 429         /* v4l2_fh support */
 430         spin_lock_init(&vdev->fh_lock);
 431         INIT_LIST_HEAD(&vdev->fh_list);
 432
 433         /* Part 1: check device type */
 434         switch (type) {
 435         case VFL_TYPE_GRABBER:
 436                 name_base = "video";
 437                 break;
 438         case VFL_TYPE_VBI:
 439                 name_base = "vbi";
 440                 break;
 441         case VFL_TYPE_RADIO:
 442                 name_base = "radio";
 443                 break;
 444         default:
 445                 printk(KERN_ERR "%s called with unknown type: %d\n",
 446                        __func__, type);
 447                 return -EINVAL;
 448         }
 449
 450         vdev->vfl_type = type;
 451         vdev->cdev = NULL;
 452         if (vdev->v4l2_dev) {
 453                 if (vdev->v4l2_dev->dev)
 454                         vdev->parent = vdev->v4l2_dev->dev;
 455                 if (vdev->ctrl_handler == NULL)
 456                         vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
 457         }
 458
 459         /* Part 2: find a free minor, device node number and device index. */
 460 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 461         /* Keep the ranges for the first four types for historical
 462          * reasons.
 463          * Newer devices (not yet in place) should use the range
 464          * of 128-191 and just pick the first free minor there
 465          * (new style). */
 466         switch (type) {
 467         case VFL_TYPE_GRABBER:
 468                 minor_offset = 0;
 469                 minor_cnt = 64;
 470                 break;
 471         case VFL_TYPE_RADIO:
 472                 minor_offset = 64;
 473                 minor_cnt = 64;
 474                 break;
 475         case VFL_TYPE_VBI:
 476                 minor_offset = 224;
 477                 minor_cnt = 32;
 478                 break;
 479         default:
 480                 minor_offset = 128;
 481                 minor_cnt = 64;
 482                 break;
 483         }
 484 #endif
 485
 486         /* Pick a device node number */
 487         mutex_lock(&videodev_lock);
 488         nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
 489         if (nr == minor_cnt)
 490                 nr = devnode_find(vdev, 0, minor_cnt);
 491         if (nr == minor_cnt) {
 492                 printk(KERN_ERR "could not get a free device node number\n");
 493                 mutex_unlock(&videodev_lock);
 494                 return -ENFILE;
 495         }
 496 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 497         /* 1-on-1 mapping of device node number to minor number */
 498         i = nr;
 499 #else
 500         /* The device node number and minor numbers are independent, so
 501            we just find the first free minor number. */
 502         for (i = 0; i < VIDEO_NUM_DEVICES; i++)
 503                 if (video_device[i] == NULL)
 504                         break;
 505         if (i == VIDEO_NUM_DEVICES) {
 506                 mutex_unlock(&videodev_lock);
 507                 printk(KERN_ERR "could not get a free minor\n");
 508                 return -ENFILE;
 509         }
 510 #endif
 511         vdev->minor = i + minor_offset;
 512         vdev->num = nr;
 513         devnode_set(vdev);
 514
 515         /* Should not happen since we thought this minor was free */
 516         WARN_ON(video_device[vdev->minor] != NULL);
 517         vdev->index = get_index(vdev);
 518         mutex_unlock(&videodev_lock);
 519
 520         /* Part 3: Initialize the character device */
 521         vdev->cdev = cdev_alloc();
 522         if (vdev->cdev == NULL) {
 523                 ret = -ENOMEM;
 524                 goto cleanup;
 525         }
 526         vdev->cdev->ops = &v4l2_fops;
 527         vdev->cdev->owner = vdev->fops->owner;
 528         ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
 529         if (ret < 0) {
 530                 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
 531                 kfree(vdev->cdev);
 532                 vdev->cdev = NULL;
 533                 goto cleanup;
 534         }
 535
 536         /* Part 4: register the device with sysfs */
 537         memset(&vdev->dev, 0, sizeof(vdev->dev));
 538         /* The memset above cleared the device's device_private, so
 539            put back the copy we made earlier. */
 540         vdev->dev.p = priv;
 541         vdev->dev.class = &video_class;
 542         vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
 543         if (vdev->parent)
 544                 vdev->dev.parent = vdev->parent;
 545         dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
 546         ret = device_register(&vdev->dev);
 547         if (ret < 0) {
 548                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 549                 goto cleanup;
 550         }
 551         /* Register the release callback that will be called when the last
 552            reference to the device goes away. */
 553         vdev->dev.release = v4l2_device_release;
 554
 555         if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
 556                 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
 557                         name_base, nr, video_device_node_name(vdev));
 558
 559         /* Part 5: Activate this minor. The char device can now be used. */
 560         set_bit(V4L2_FL_REGISTERED, &vdev->flags);
 561         mutex_lock(&videodev_lock);
 562         video_device[vdev->minor] = vdev;
 563         mutex_unlock(&videodev_lock);
 564         return 0;
 565
 566 cleanup:
 567         mutex_lock(&videodev_lock);
 568         if (vdev->cdev)
 569                 cdev_del(vdev->cdev);
 570         devnode_clear(vdev);
 571         mutex_unlock(&videodev_lock);
 572         /* Mark this video device as never having been registered. */
 573         vdev->minor = -1;
 574         return ret;
 575 }
 576
 577 int video_register_device(struct video_device *vdev, int type, int nr)
 578 {
 579         return __video_register_device(vdev, type, nr, 1);
 580 }
 581 EXPORT_SYMBOL(video_register_device);
 582
 583 int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
 584 {
 585         return __video_register_device(vdev, type, nr, 0);
 586 }
 587 EXPORT_SYMBOL(video_register_device_no_warn);
 588
 589 /**
 590  *      video_unregister_device - unregister a video4linux device
 591  *      @vdev: the device to unregister
 592  *
 593  *      This unregisters the passed device. Future open calls will
 594  *      be met with errors.
 595  */
 596 void video_unregister_device(struct video_device *vdev)
 597 {
 598         /* Check if vdev was ever registered at all */
 599         if (!vdev || !video_is_registered(vdev))
 600                 return;
 601
 602         clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
 603         device_unregister(&vdev->dev);
 604 }
 605 EXPORT_SYMBOL(video_unregister_device);
 606
 607 /*
 608  *      Initialise video for linux
 609  */
 610 static int __init videodev_init(void)
 611 {
 612         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 613         int ret;
 614
 615         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 616         ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 617         if (ret < 0) {
 618                 printk(KERN_WARNING "videodev: unable to get major %d\n",
 619                                 VIDEO_MAJOR);
 620                 return ret;
 621         }
 622
 623         ret = class_register(&video_class);
 624         if (ret < 0) {
 625                 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 626                 printk(KERN_WARNING "video_dev: class_register failed\n");
 627                 return -EIO;
 628         }
 629
 630         return 0;
 631 }
 632
 633 static void __exit videodev_exit(void)
 634 {
 635         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 636
 637         class_unregister(&video_class);
 638         unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 639 }
 640
 641 module_init(videodev_init)
 642 module_exit(videodev_exit)
 643
 644 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 645 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 646 MODULE_LICENSE("GPL");
 647 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);
 648
 649
 650 /*
 651  * Local variables:
 652  * c-basic-offset: 8
 653  * End:
 654  */