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_VTX) ? 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
 190         if (!vdev->fops->read)
 191                 return -EINVAL;
 192         if (video_is_unregistered(vdev))
 193                 return -EIO;
 194         return vdev->fops->read(filp, buf, sz, off);
 195 }
 196
 197 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
 198                 size_t sz, loff_t *off)
 199 {
 200         struct video_device *vdev = video_devdata(filp);
 201
 202         if (!vdev->fops->write)
 203                 return -EINVAL;
 204         if (video_is_unregistered(vdev))
 205                 return -EIO;
 206         return vdev->fops->write(filp, buf, sz, off);
 207 }
 208
 209 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
 210 {
 211         struct video_device *vdev = video_devdata(filp);
 212
 213         if (!vdev->fops->poll || video_is_unregistered(vdev))
 214                 return DEFAULT_POLLMASK;
 215         return vdev->fops->poll(filp, poll);
 216 }
 217
 218 static int v4l2_ioctl(struct inode *inode, struct file *filp,
 219                 unsigned int cmd, unsigned long arg)
 220 {
 221         struct video_device *vdev = video_devdata(filp);
 222
 223         if (!vdev->fops->ioctl)
 224                 return -ENOTTY;
 225         /* Allow ioctl to continue even if the device was unregistered.
 226            Things like dequeueing buffers might still be useful. */
 227         return vdev->fops->ioctl(filp, cmd, arg);
 228 }
 229
 230 static long v4l2_unlocked_ioctl(struct file *filp,
 231                 unsigned int cmd, unsigned long arg)
 232 {
 233         struct video_device *vdev = video_devdata(filp);
 234
 235         if (!vdev->fops->unlocked_ioctl)
 236                 return -ENOTTY;
 237         /* Allow ioctl to continue even if the device was unregistered.
 238            Things like dequeueing buffers might still be useful. */
 239         return vdev->fops->unlocked_ioctl(filp, cmd, arg);
 240 }
 241
 242 #ifdef CONFIG_MMU
 243 #define v4l2_get_unmapped_area NULL
 244 #else
 245 static unsigned long v4l2_get_unmapped_area(struct file *filp,
 246                 unsigned long addr, unsigned long len, unsigned long pgoff,
 247                 unsigned long flags)
 248 {
 249         struct video_device *vdev = video_devdata(filp);
 250
 251         if (!vdev->fops->get_unmapped_area)
 252                 return -ENOSYS;
 253         if (video_is_unregistered(vdev))
 254                 return -ENODEV;
 255         return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
 256 }
 257 #endif
 258
 259 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
 260 {
 261         struct video_device *vdev = video_devdata(filp);
 262
 263         if (!vdev->fops->mmap ||
 264             video_is_unregistered(vdev))
 265                 return -ENODEV;
 266         return vdev->fops->mmap(filp, vm);
 267 }
 268
 269 /* Override for the open function */
 270 static int v4l2_open(struct inode *inode, struct file *filp)
 271 {
 272         struct video_device *vdev;
 273         int ret = 0;
 274
 275         /* Check if the video device is available */
 276         mutex_lock(&videodev_lock);
 277         vdev = video_devdata(filp);
 278         /* return ENODEV if the video device has been removed
 279            already or if it is not registered anymore. */
 280         if (vdev == NULL || video_is_unregistered(vdev)) {
 281                 mutex_unlock(&videodev_lock);
 282                 return -ENODEV;
 283         }
 284         /* and increase the device refcount */
 285         video_get(vdev);
 286         mutex_unlock(&videodev_lock);
 287         if (vdev->fops->open)
 288                 ret = vdev->fops->open(filp);
 289
 290         /* decrease the refcount in case of an error */
 291         if (ret)
 292                 video_put(vdev);
 293         return ret;
 294 }
 295
 296 /* Override for the release function */
 297 static int v4l2_release(struct inode *inode, struct file *filp)
 298 {
 299         struct video_device *vdev = video_devdata(filp);
 300         int ret = 0;
 301
 302         if (vdev->fops->release)
 303                 vdev->fops->release(filp);
 304
 305         /* decrease the refcount unconditionally since the release()
 306            return value is ignored. */
 307         video_put(vdev);
 308         return ret;
 309 }
 310
 311 static const struct file_operations v4l2_unlocked_fops = {
 312         .owner = THIS_MODULE,
 313         .read = v4l2_read,
 314         .write = v4l2_write,
 315         .open = v4l2_open,
 316         .get_unmapped_area = v4l2_get_unmapped_area,
 317         .mmap = v4l2_mmap,
 318         .unlocked_ioctl = v4l2_unlocked_ioctl,
 319 #ifdef CONFIG_COMPAT
 320         .compat_ioctl = v4l2_compat_ioctl32,
 321 #endif
 322         .release = v4l2_release,
 323         .poll = v4l2_poll,
 324         .llseek = no_llseek,
 325 };
 326
 327 static const struct file_operations v4l2_fops = {
 328         .owner = THIS_MODULE,
 329         .read = v4l2_read,
 330         .write = v4l2_write,
 331         .open = v4l2_open,
 332         .get_unmapped_area = v4l2_get_unmapped_area,
 333         .mmap = v4l2_mmap,
 334         .ioctl = v4l2_ioctl,
 335 #ifdef CONFIG_COMPAT
 336         .compat_ioctl = v4l2_compat_ioctl32,
 337 #endif
 338         .release = v4l2_release,
 339         .poll = v4l2_poll,
 340         .llseek = no_llseek,
 341 };
 342
 343 /**
 344  * get_index - assign stream index number based on parent device
 345  * @vdev: video_device to assign index number to, vdev->parent should be assigned
 346  *
 347  * Note that when this is called the new device has not yet been registered
 348  * in the video_device array, but it was able to obtain a minor number.
 349  *
 350  * This means that we can always obtain a free stream index number since
 351  * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
 352  * use of the video_device array.
 353  *
 354  * Returns a free index number.
 355  */
 356 static int get_index(struct video_device *vdev)
 357 {
 358         /* This can be static since this function is called with the global
 359            videodev_lock held. */
 360         static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
 361         int i;
 362
 363         /* Some drivers do not set the parent. In that case always return 0. */
 364         if (vdev->parent == NULL)
 365                 return 0;
 366
 367         bitmap_zero(used, VIDEO_NUM_DEVICES);
 368
 369         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 370                 if (video_device[i] != NULL &&
 371                     video_device[i]->parent == vdev->parent) {
 372                         set_bit(video_device[i]->index, used);
 373                 }
 374         }
 375
 376         return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
 377 }
 378
 379 /**
 380  *      video_register_device - register video4linux devices
 381  *      @vdev: video device structure we want to register
 382  *      @type: type of device to register
 383  *      @nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...
 384  *             -1 == first free)
 385  *      @warn_if_nr_in_use: warn if the desired device node number
 386  *             was already in use and another number was chosen instead.
 387  *
 388  *      The registration code assigns minor numbers and device node numbers
 389  *      based on the requested type and registers the new device node with
 390  *      the kernel.
 391  *      An error is returned if no free minor or device node number could be
 392  *      found, or if the registration of the device node failed.
 393  *
 394  *      Zero is returned on success.
 395  *
 396  *      Valid types are
 397  *
 398  *      %VFL_TYPE_GRABBER - A frame grabber
 399  *
 400  *      %VFL_TYPE_VTX - A teletext device
 401  *
 402  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 403  *
 404  *      %VFL_TYPE_RADIO - A radio card
 405  */
 406 static int __video_register_device(struct video_device *vdev, int type, int nr,
 407                 int warn_if_nr_in_use)
 408 {
 409         int i = 0;
 410         int ret;
 411         int minor_offset = 0;
 412         int minor_cnt = VIDEO_NUM_DEVICES;
 413         const char *name_base;
 414         void *priv = video_get_drvdata(vdev);
 415
 416         /* A minor value of -1 marks this video device as never
 417            having been registered */
 418         vdev->minor = -1;
 419
 420         /* the release callback MUST be present */
 421         WARN_ON(!vdev->release);
 422         if (!vdev->release)
 423                 return -EINVAL;
 424
 425         /* Part 1: check device type */
 426         switch (type) {
 427         case VFL_TYPE_GRABBER:
 428                 name_base = "video";
 429                 break;
 430         case VFL_TYPE_VTX:
 431                 name_base = "vtx";
 432                 break;
 433         case VFL_TYPE_VBI:
 434                 name_base = "vbi";
 435                 break;
 436         case VFL_TYPE_RADIO:
 437                 name_base = "radio";
 438                 break;
 439         default:
 440                 printk(KERN_ERR "%s called with unknown type: %d\n",
 441                        __func__, type);
 442                 return -EINVAL;
 443         }
 444
 445         vdev->vfl_type = type;
 446         vdev->cdev = NULL;
 447         if (vdev->v4l2_dev && vdev->v4l2_dev->dev)
 448                 vdev->parent = vdev->v4l2_dev->dev;
 449
 450         /* Part 2: find a free minor, device node number and device index. */
 451 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 452         /* Keep the ranges for the first four types for historical
 453          * reasons.
 454          * Newer devices (not yet in place) should use the range
 455          * of 128-191 and just pick the first free minor there
 456          * (new style). */
 457         switch (type) {
 458         case VFL_TYPE_GRABBER:
 459                 minor_offset = 0;
 460                 minor_cnt = 64;
 461                 break;
 462         case VFL_TYPE_RADIO:
 463                 minor_offset = 64;
 464                 minor_cnt = 64;
 465                 break;
 466         case VFL_TYPE_VTX:
 467                 minor_offset = 192;
 468                 minor_cnt = 32;
 469                 break;
 470         case VFL_TYPE_VBI:
 471                 minor_offset = 224;
 472                 minor_cnt = 32;
 473                 break;
 474         default:
 475                 minor_offset = 128;
 476                 minor_cnt = 64;
 477                 break;
 478         }
 479 #endif
 480
 481         /* Pick a device node number */
 482         mutex_lock(&videodev_lock);
 483         nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
 484         if (nr == minor_cnt)
 485                 nr = devnode_find(vdev, 0, minor_cnt);
 486         if (nr == minor_cnt) {
 487                 printk(KERN_ERR "could not get a free device node number\n");
 488                 mutex_unlock(&videodev_lock);
 489                 return -ENFILE;
 490         }
 491 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 492         /* 1-on-1 mapping of device node number to minor number */
 493         i = nr;
 494 #else
 495         /* The device node number and minor numbers are independent, so
 496            we just find the first free minor number. */
 497         for (i = 0; i < VIDEO_NUM_DEVICES; i++)
 498                 if (video_device[i] == NULL)
 499                         break;
 500         if (i == VIDEO_NUM_DEVICES) {
 501                 mutex_unlock(&videodev_lock);
 502                 printk(KERN_ERR "could not get a free minor\n");
 503                 return -ENFILE;
 504         }
 505 #endif
 506         vdev->minor = i + minor_offset;
 507         vdev->num = nr;
 508         devnode_set(vdev);
 509
 510         /* Should not happen since we thought this minor was free */
 511         WARN_ON(video_device[vdev->minor] != NULL);
 512         vdev->index = get_index(vdev);
 513         mutex_unlock(&videodev_lock);
 514
 515         /* Part 3: Initialize the character device */
 516         vdev->cdev = cdev_alloc();
 517         if (vdev->cdev == NULL) {
 518                 ret = -ENOMEM;
 519                 goto cleanup;
 520         }
 521         if (vdev->fops->unlocked_ioctl)
 522                 vdev->cdev->ops = &v4l2_unlocked_fops;
 523         else
 524                 vdev->cdev->ops = &v4l2_fops;
 525         vdev->cdev->owner = vdev->fops->owner;
 526         ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
 527         if (ret < 0) {
 528                 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
 529                 kfree(vdev->cdev);
 530                 vdev->cdev = NULL;
 531                 goto cleanup;
 532         }
 533
 534         /* Part 4: register the device with sysfs */
 535         memset(&vdev->dev, 0, sizeof(vdev->dev));
 536         /* The memset above cleared the device's drvdata, so
 537            put back the copy we made earlier. */
 538         video_set_drvdata(vdev, priv);
 539         vdev->dev.class = &video_class;
 540         vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
 541         if (vdev->parent)
 542                 vdev->dev.parent = vdev->parent;
 543         dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
 544         ret = device_register(&vdev->dev);
 545         if (ret < 0) {
 546                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 547                 goto cleanup;
 548         }
 549         /* Register the release callback that will be called when the last
 550            reference to the device goes away. */
 551         vdev->dev.release = v4l2_device_release;
 552
 553         if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
 554                 printk(KERN_WARNING "%s: requested %s%d, got %s%d\n",
 555                                 __func__, name_base, nr, name_base, vdev->num);
 556
 557         /* Part 5: Activate this minor. The char device can now be used. */
 558         mutex_lock(&videodev_lock);
 559         video_device[vdev->minor] = vdev;
 560         mutex_unlock(&videodev_lock);
 561         return 0;
 562
 563 cleanup:
 564         mutex_lock(&videodev_lock);
 565         if (vdev->cdev)
 566                 cdev_del(vdev->cdev);
 567         devnode_clear(vdev);
 568         mutex_unlock(&videodev_lock);
 569         /* Mark this video device as never having been registered. */
 570         vdev->minor = -1;
 571         return ret;
 572 }
 573
 574 int video_register_device(struct video_device *vdev, int type, int nr)
 575 {
 576         return __video_register_device(vdev, type, nr, 1);
 577 }
 578 EXPORT_SYMBOL(video_register_device);
 579
 580 int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
 581 {
 582         return __video_register_device(vdev, type, nr, 0);
 583 }
 584 EXPORT_SYMBOL(video_register_device_no_warn);
 585
 586 /**
 587  *      video_unregister_device - unregister a video4linux device
 588  *      @vdev: the device to unregister
 589  *
 590  *      This unregisters the passed device. Future open calls will
 591  *      be met with errors.
 592  */
 593 void video_unregister_device(struct video_device *vdev)
 594 {
 595         /* Check if vdev was ever registered at all */
 596         if (!vdev || vdev->minor < 0)
 597                 return;
 598
 599         mutex_lock(&videodev_lock);
 600         set_bit(V4L2_FL_UNREGISTERED, &vdev->flags);
 601         mutex_unlock(&videodev_lock);
 602         device_unregister(&vdev->dev);
 603 }
 604 EXPORT_SYMBOL(video_unregister_device);
 605
 606 /*
 607  *      Initialise video for linux
 608  */
 609 static int __init videodev_init(void)
 610 {
 611         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 612         int ret;
 613
 614         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 615         ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 616         if (ret < 0) {
 617                 printk(KERN_WARNING "videodev: unable to get major %d\n",
 618                                 VIDEO_MAJOR);
 619                 return ret;
 620         }
 621
 622         ret = class_register(&video_class);
 623         if (ret < 0) {
 624                 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 625                 printk(KERN_WARNING "video_dev: class_register failed\n");
 626                 return -EIO;
 627         }
 628
 629         return 0;
 630 }
 631
 632 static void __exit videodev_exit(void)
 633 {
 634         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 635
 636         class_unregister(&video_class);
 637         unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 638 }
 639
 640 module_init(videodev_init)
 641 module_exit(videodev_exit)
 642
 643 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 644 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 645 MODULE_LICENSE("GPL");
 646 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);
 647
 648
 649 /*
 650  * Local variables:
 651  * c-basic-offset: 8
 652  * End:
 653  */