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 <linux/smp_lock.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/system.h>
  31
  32 #include <media/v4l2-common.h>
  33 #include <media/v4l2-device.h>
  34 #include <media/v4l2-ioctl.h>
  35
  36 #define VIDEO_NUM_DEVICES       256
  37 #define VIDEO_NAME              "video4linux"
  38
  39 /*
  40  *      sysfs stuff
  41  */
  42
  43 static ssize_t show_index(struct device *cd,
  44                          struct device_attribute *attr, char *buf)
  45 {
  46         struct video_device *vdev = to_video_device(cd);
  47
  48         return sprintf(buf, "%i\n", vdev->index);
  49 }
  50
  51 static ssize_t show_name(struct device *cd,
  52                          struct device_attribute *attr, char *buf)
  53 {
  54         struct video_device *vdev = to_video_device(cd);
  55
  56         return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
  57 }
  58
  59 static struct device_attribute video_device_attrs[] = {
  60         __ATTR(name, S_IRUGO, show_name, NULL),
  61         __ATTR(index, S_IRUGO, show_index, NULL),
  62         __ATTR_NULL
  63 };
  64
  65 /*
  66  *      Active devices
  67  */
  68 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  69 static DEFINE_MUTEX(videodev_lock);
  70 static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
  71
  72 /* Device node utility functions */
  73
  74 /* Note: these utility functions all assume that vfl_type is in the range
  75    [0, VFL_TYPE_MAX-1]. */
  76
  77 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
  78 /* Return the bitmap corresponding to vfl_type. */
  79 static inline unsigned long *devnode_bits(int vfl_type)
  80 {
  81         /* Any types not assigned to fixed minor ranges must be mapped to
  82            one single bitmap for the purposes of finding a free node number
  83            since all those unassigned types use the same minor range. */
  84         int idx = (vfl_type > VFL_TYPE_VTX) ? VFL_TYPE_MAX - 1 : vfl_type;
  85
  86         return devnode_nums[idx];
  87 }
  88 #else
  89 /* Return the bitmap corresponding to vfl_type. */
  90 static inline unsigned long *devnode_bits(int vfl_type)
  91 {
  92         return devnode_nums[vfl_type];
  93 }
  94 #endif
  95
  96 /* Mark device node number vdev->num as used */
  97 static inline void devnode_set(struct video_device *vdev)
  98 {
  99         set_bit(vdev->num, devnode_bits(vdev->vfl_type));
 100 }
 101
 102 /* Mark device node number vdev->num as unused */
 103 static inline void devnode_clear(struct video_device *vdev)
 104 {
 105         clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
 106 }
 107
 108 /* Try to find a free device node number in the range [from, to> */
 109 static inline int devnode_find(struct video_device *vdev, int from, int to)
 110 {
 111         return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
 112 }
 113
 114 struct video_device *video_device_alloc(void)
 115 {
 116         return kzalloc(sizeof(struct video_device), GFP_KERNEL);
 117 }
 118 EXPORT_SYMBOL(video_device_alloc);
 119
 120 void video_device_release(struct video_device *vdev)
 121 {
 122         kfree(vdev);
 123 }
 124 EXPORT_SYMBOL(video_device_release);
 125
 126 void video_device_release_empty(struct video_device *vdev)
 127 {
 128         /* Do nothing */
 129         /* Only valid when the video_device struct is a static. */
 130 }
 131 EXPORT_SYMBOL(video_device_release_empty);
 132
 133 static inline void video_get(struct video_device *vdev)
 134 {
 135         get_device(&vdev->dev);
 136 }
 137
 138 static inline void video_put(struct video_device *vdev)
 139 {
 140         put_device(&vdev->dev);
 141 }
 142
 143 /* Called when the last user of the video device exits. */
 144 static void v4l2_device_release(struct device *cd)
 145 {
 146         struct video_device *vdev = to_video_device(cd);
 147
 148         mutex_lock(&videodev_lock);
 149         if (video_device[vdev->minor] != vdev) {
 150                 mutex_unlock(&videodev_lock);
 151                 /* should not happen */
 152                 WARN_ON(1);
 153                 return;
 154         }
 155
 156         /* Free up this device for reuse */
 157         video_device[vdev->minor] = NULL;
 158
 159         /* Delete the cdev on this minor as well */
 160         cdev_del(vdev->cdev);
 161         /* Just in case some driver tries to access this from
 162            the release() callback. */
 163         vdev->cdev = NULL;
 164
 165         /* Mark device node number as free */
 166         devnode_clear(vdev);
 167
 168         mutex_unlock(&videodev_lock);
 169
 170         /* Release video_device and perform other
 171            cleanups as needed. */
 172         vdev->release(vdev);
 173 }
 174
 175 static struct class video_class = {
 176         .name = VIDEO_NAME,
 177         .dev_attrs = video_device_attrs,
 178 };
 179
 180 struct video_device *video_devdata(struct file *file)
 181 {
 182         return video_device[iminor(file->f_path.dentry->d_inode)];
 183 }
 184 EXPORT_SYMBOL(video_devdata);
 185
 186 static ssize_t v4l2_read(struct file *filp, char __user *buf,
 187                 size_t sz, loff_t *off)
 188 {
 189         struct video_device *vdev = video_devdata(filp);
 190
 191         if (!vdev->fops->read)
 192                 return -EINVAL;
 193         if (!video_is_registered(vdev))
 194                 return -EIO;
 195         return vdev->fops->read(filp, buf, sz, off);
 196 }
 197
 198 static ssize_t v4l2_write(struct file *filp, const char __user *buf,
 199                 size_t sz, loff_t *off)
 200 {
 201         struct video_device *vdev = video_devdata(filp);
 202
 203         if (!vdev->fops->write)
 204                 return -EINVAL;
 205         if (!video_is_registered(vdev))
 206                 return -EIO;
 207         return vdev->fops->write(filp, buf, sz, off);
 208 }
 209
 210 static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
 211 {
 212         struct video_device *vdev = video_devdata(filp);
 213
 214         if (!vdev->fops->poll || !video_is_registered(vdev))
 215                 return DEFAULT_POLLMASK;
 216         return vdev->fops->poll(filp, poll);
 217 }
 218
 219 static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 220 {
 221         struct video_device *vdev = video_devdata(filp);
 222         int ret;
 223
 224         /* Allow ioctl to continue even if the device was unregistered.
 225            Things like dequeueing buffers might still be useful. */
 226         if (vdev->fops->unlocked_ioctl) {
 227                 ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
 228         } else if (vdev->fops->ioctl) {
 229                 /* TODO: convert all drivers to unlocked_ioctl */
 230                 lock_kernel();
 231                 ret = vdev->fops->ioctl(filp, cmd, arg);
 232                 unlock_kernel();
 233         } else
 234                 ret = -ENOTTY;
 235
 236         return ret;
 237 }
 238
 239 #ifdef CONFIG_MMU
 240 #define v4l2_get_unmapped_area NULL
 241 #else
 242 static unsigned long v4l2_get_unmapped_area(struct file *filp,
 243                 unsigned long addr, unsigned long len, unsigned long pgoff,
 244                 unsigned long flags)
 245 {
 246         struct video_device *vdev = video_devdata(filp);
 247
 248         if (!vdev->fops->get_unmapped_area)
 249                 return -ENOSYS;
 250         if (!video_is_registered(vdev))
 251                 return -ENODEV;
 252         return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
 253 }
 254 #endif
 255
 256 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
 257 {
 258         struct video_device *vdev = video_devdata(filp);
 259
 260         if (!vdev->fops->mmap || !video_is_registered(vdev))
 261                 return -ENODEV;
 262         return vdev->fops->mmap(filp, vm);
 263 }
 264
 265 /* Override for the open function */
 266 static int v4l2_open(struct inode *inode, struct file *filp)
 267 {
 268         struct video_device *vdev;
 269         int ret = 0;
 270
 271         /* Check if the video device is available */
 272         mutex_lock(&videodev_lock);
 273         vdev = video_devdata(filp);
 274         /* return ENODEV if the video device has been removed
 275            already or if it is not registered anymore. */
 276         if (vdev == NULL || !video_is_registered(vdev)) {
 277                 mutex_unlock(&videodev_lock);
 278                 return -ENODEV;
 279         }
 280         /* and increase the device refcount */
 281         video_get(vdev);
 282         mutex_unlock(&videodev_lock);
 283         if (vdev->fops->open)
 284                 ret = vdev->fops->open(filp);
 285
 286         /* decrease the refcount in case of an error */
 287         if (ret)
 288                 video_put(vdev);
 289         return ret;
 290 }
 291
 292 /* Override for the release function */
 293 static int v4l2_release(struct inode *inode, struct file *filp)
 294 {
 295         struct video_device *vdev = video_devdata(filp);
 296         int ret = 0;
 297
 298         if (vdev->fops->release)
 299                 vdev->fops->release(filp);
 300
 301         /* decrease the refcount unconditionally since the release()
 302            return value is ignored. */
 303         video_put(vdev);
 304         return ret;
 305 }
 306
 307 static const struct file_operations v4l2_fops = {
 308         .owner = THIS_MODULE,
 309         .read = v4l2_read,
 310         .write = v4l2_write,
 311         .open = v4l2_open,
 312         .get_unmapped_area = v4l2_get_unmapped_area,
 313         .mmap = v4l2_mmap,
 314         .unlocked_ioctl = v4l2_ioctl,
 315 #ifdef CONFIG_COMPAT
 316         .compat_ioctl = v4l2_compat_ioctl32,
 317 #endif
 318         .release = v4l2_release,
 319         .poll = v4l2_poll,
 320         .llseek = no_llseek,
 321 };
 322
 323 /**
 324  * get_index - assign stream index number based on parent device
 325  * @vdev: video_device to assign index number to, vdev->parent should be assigned
 326  *
 327  * Note that when this is called the new device has not yet been registered
 328  * in the video_device array, but it was able to obtain a minor number.
 329  *
 330  * This means that we can always obtain a free stream index number since
 331  * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
 332  * use of the video_device array.
 333  *
 334  * Returns a free index number.
 335  */
 336 static int get_index(struct video_device *vdev)
 337 {
 338         /* This can be static since this function is called with the global
 339            videodev_lock held. */
 340         static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
 341         int i;
 342
 343         /* Some drivers do not set the parent. In that case always return 0. */
 344         if (vdev->parent == NULL)
 345                 return 0;
 346
 347         bitmap_zero(used, VIDEO_NUM_DEVICES);
 348
 349         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 350                 if (video_device[i] != NULL &&
 351                     video_device[i]->parent == vdev->parent) {
 352                         set_bit(video_device[i]->index, used);
 353                 }
 354         }
 355
 356         return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
 357 }
 358
 359 /**
 360  *      video_register_device - register video4linux devices
 361  *      @vdev: video device structure we want to register
 362  *      @type: type of device to register
 363  *      @nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...
 364  *             -1 == first free)
 365  *      @warn_if_nr_in_use: warn if the desired device node number
 366  *             was already in use and another number was chosen instead.
 367  *
 368  *      The registration code assigns minor numbers and device node numbers
 369  *      based on the requested type and registers the new device node with
 370  *      the kernel.
 371  *      An error is returned if no free minor or device node number could be
 372  *      found, or if the registration of the device node failed.
 373  *
 374  *      Zero is returned on success.
 375  *
 376  *      Valid types are
 377  *
 378  *      %VFL_TYPE_GRABBER - A frame grabber
 379  *
 380  *      %VFL_TYPE_VTX - A teletext device
 381  *
 382  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 383  *
 384  *      %VFL_TYPE_RADIO - A radio card
 385  */
 386 static int __video_register_device(struct video_device *vdev, int type, int nr,
 387                 int warn_if_nr_in_use)
 388 {
 389         int i = 0;
 390         int ret;
 391         int minor_offset = 0;
 392         int minor_cnt = VIDEO_NUM_DEVICES;
 393         const char *name_base;
 394         void *priv = vdev->dev.p;
 395
 396         /* A minor value of -1 marks this video device as never
 397            having been registered */
 398         vdev->minor = -1;
 399
 400         /* the release callback MUST be present */
 401         WARN_ON(!vdev->release);
 402         if (!vdev->release)
 403                 return -EINVAL;
 404
 405         /* v4l2_fh support */
 406         spin_lock_init(&vdev->fh_lock);
 407         INIT_LIST_HEAD(&vdev->fh_list);
 408
 409         /* Part 1: check device type */
 410         switch (type) {
 411         case VFL_TYPE_GRABBER:
 412                 name_base = "video";
 413                 break;
 414         case VFL_TYPE_VTX:
 415                 name_base = "vtx";
 416                 break;
 417         case VFL_TYPE_VBI:
 418                 name_base = "vbi";
 419                 break;
 420         case VFL_TYPE_RADIO:
 421                 name_base = "radio";
 422                 break;
 423         default:
 424                 printk(KERN_ERR "%s called with unknown type: %d\n",
 425                        __func__, type);
 426                 return -EINVAL;
 427         }
 428
 429         vdev->vfl_type = type;
 430         vdev->cdev = NULL;
 431         if (vdev->v4l2_dev) {
 432                 if (vdev->v4l2_dev->dev)
 433                         vdev->parent = vdev->v4l2_dev->dev;
 434                 if (vdev->ctrl_handler == NULL)
 435                         vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
 436         }
 437
 438         /* Part 2: find a free minor, device node number and device index. */
 439 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 440         /* Keep the ranges for the first four types for historical
 441          * reasons.
 442          * Newer devices (not yet in place) should use the range
 443          * of 128-191 and just pick the first free minor there
 444          * (new style). */
 445         switch (type) {
 446         case VFL_TYPE_GRABBER:
 447                 minor_offset = 0;
 448                 minor_cnt = 64;
 449                 break;
 450         case VFL_TYPE_RADIO:
 451                 minor_offset = 64;
 452                 minor_cnt = 64;
 453                 break;
 454         case VFL_TYPE_VTX:
 455                 minor_offset = 192;
 456                 minor_cnt = 32;
 457                 break;
 458         case VFL_TYPE_VBI:
 459                 minor_offset = 224;
 460                 minor_cnt = 32;
 461                 break;
 462         default:
 463                 minor_offset = 128;
 464                 minor_cnt = 64;
 465                 break;
 466         }
 467 #endif
 468
 469         /* Pick a device node number */
 470         mutex_lock(&videodev_lock);
 471         nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
 472         if (nr == minor_cnt)
 473                 nr = devnode_find(vdev, 0, minor_cnt);
 474         if (nr == minor_cnt) {
 475                 printk(KERN_ERR "could not get a free device node number\n");
 476                 mutex_unlock(&videodev_lock);
 477                 return -ENFILE;
 478         }
 479 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 480         /* 1-on-1 mapping of device node number to minor number */
 481         i = nr;
 482 #else
 483         /* The device node number and minor numbers are independent, so
 484            we just find the first free minor number. */
 485         for (i = 0; i < VIDEO_NUM_DEVICES; i++)
 486                 if (video_device[i] == NULL)
 487                         break;
 488         if (i == VIDEO_NUM_DEVICES) {
 489                 mutex_unlock(&videodev_lock);
 490                 printk(KERN_ERR "could not get a free minor\n");
 491                 return -ENFILE;
 492         }
 493 #endif
 494         vdev->minor = i + minor_offset;
 495         vdev->num = nr;
 496         devnode_set(vdev);
 497
 498         /* Should not happen since we thought this minor was free */
 499         WARN_ON(video_device[vdev->minor] != NULL);
 500         vdev->index = get_index(vdev);
 501         mutex_unlock(&videodev_lock);
 502
 503         /* Part 3: Initialize the character device */
 504         vdev->cdev = cdev_alloc();
 505         if (vdev->cdev == NULL) {
 506                 ret = -ENOMEM;
 507                 goto cleanup;
 508         }
 509         vdev->cdev->ops = &v4l2_fops;
 510         vdev->cdev->owner = vdev->fops->owner;
 511         ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
 512         if (ret < 0) {
 513                 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
 514                 kfree(vdev->cdev);
 515                 vdev->cdev = NULL;
 516                 goto cleanup;
 517         }
 518
 519         /* Part 4: register the device with sysfs */
 520         memset(&vdev->dev, 0, sizeof(vdev->dev));
 521         /* The memset above cleared the device's device_private, so
 522            put back the copy we made earlier. */
 523         vdev->dev.p = priv;
 524         vdev->dev.class = &video_class;
 525         vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
 526         if (vdev->parent)
 527                 vdev->dev.parent = vdev->parent;
 528         dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
 529         ret = device_register(&vdev->dev);
 530         if (ret < 0) {
 531                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 532                 goto cleanup;
 533         }
 534         /* Register the release callback that will be called when the last
 535            reference to the device goes away. */
 536         vdev->dev.release = v4l2_device_release;
 537
 538         if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
 539                 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
 540                         name_base, nr, video_device_node_name(vdev));
 541
 542         /* Part 5: Activate this minor. The char device can now be used. */
 543         set_bit(V4L2_FL_REGISTERED, &vdev->flags);
 544         mutex_lock(&videodev_lock);
 545         video_device[vdev->minor] = vdev;
 546         mutex_unlock(&videodev_lock);
 547         return 0;
 548
 549 cleanup:
 550         mutex_lock(&videodev_lock);
 551         if (vdev->cdev)
 552                 cdev_del(vdev->cdev);
 553         devnode_clear(vdev);
 554         mutex_unlock(&videodev_lock);
 555         /* Mark this video device as never having been registered. */
 556         vdev->minor = -1;
 557         return ret;
 558 }
 559
 560 int video_register_device(struct video_device *vdev, int type, int nr)
 561 {
 562         return __video_register_device(vdev, type, nr, 1);
 563 }
 564 EXPORT_SYMBOL(video_register_device);
 565
 566 int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
 567 {
 568         return __video_register_device(vdev, type, nr, 0);
 569 }
 570 EXPORT_SYMBOL(video_register_device_no_warn);
 571
 572 /**
 573  *      video_unregister_device - unregister a video4linux device
 574  *      @vdev: the device to unregister
 575  *
 576  *      This unregisters the passed device. Future open calls will
 577  *      be met with errors.
 578  */
 579 void video_unregister_device(struct video_device *vdev)
 580 {
 581         /* Check if vdev was ever registered at all */
 582         if (!vdev || !video_is_registered(vdev))
 583                 return;
 584
 585         clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
 586         device_unregister(&vdev->dev);
 587 }
 588 EXPORT_SYMBOL(video_unregister_device);
 589
 590 /*
 591  *      Initialise video for linux
 592  */
 593 static int __init videodev_init(void)
 594 {
 595         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 596         int ret;
 597
 598         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 599         ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 600         if (ret < 0) {
 601                 printk(KERN_WARNING "videodev: unable to get major %d\n",
 602                                 VIDEO_MAJOR);
 603                 return ret;
 604         }
 605
 606         ret = class_register(&video_class);
 607         if (ret < 0) {
 608                 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 609                 printk(KERN_WARNING "video_dev: class_register failed\n");
 610                 return -EIO;
 611         }
 612
 613         return 0;
 614 }
 615
 616 static void __exit videodev_exit(void)
 617 {
 618         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 619
 620         class_unregister(&video_class);
 621         unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 622 }
 623
 624 module_init(videodev_init)
 625 module_exit(videodev_exit)
 626
 627 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 628 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 629 MODULE_LICENSE("GPL");
 630 MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);
 631
 632
 633 /*
 634  * Local variables:
 635  * c-basic-offset: 8
 636  * End:
 637  */