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@redhat.com> (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
  34 #define VIDEO_NUM_DEVICES       256
  35 #define VIDEO_NAME              "video4linux"
  36
  37 /*
  38  *      sysfs stuff
  39  */
  40
  41 static ssize_t show_index(struct device *cd,
  42                          struct device_attribute *attr, char *buf)
  43 {
  44         struct video_device *vfd = container_of(cd, struct video_device, dev);
  45
  46         return sprintf(buf, "%i\n", vfd->index);
  47 }
  48
  49 static ssize_t show_name(struct device *cd,
  50                          struct device_attribute *attr, char *buf)
  51 {
  52         struct video_device *vfd = container_of(cd, struct video_device, dev);
  53
  54         return sprintf(buf, "%.*s\n", (int)sizeof(vfd->name), vfd->name);
  55 }
  56
  57 static struct device_attribute video_device_attrs[] = {
  58         __ATTR(name, S_IRUGO, show_name, NULL),
  59         __ATTR(index, S_IRUGO, show_index, NULL),
  60         __ATTR_NULL
  61 };
  62
  63 /*
  64  *      Active devices
  65  */
  66 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  67 static DEFINE_MUTEX(videodev_lock);
  68 static DECLARE_BITMAP(video_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
  69
  70 struct video_device *video_device_alloc(void)
  71 {
  72         return kzalloc(sizeof(struct video_device), GFP_KERNEL);
  73 }
  74 EXPORT_SYMBOL(video_device_alloc);
  75
  76 void video_device_release(struct video_device *vfd)
  77 {
  78         kfree(vfd);
  79 }
  80 EXPORT_SYMBOL(video_device_release);
  81
  82 void video_device_release_empty(struct video_device *vfd)
  83 {
  84         /* Do nothing */
  85         /* Only valid when the video_device struct is a static. */
  86 }
  87 EXPORT_SYMBOL(video_device_release_empty);
  88
  89 /* Called when the last user of the character device is gone. */
  90 static void v4l2_chardev_release(struct kobject *kobj)
  91 {
  92         struct video_device *vfd = container_of(kobj, struct video_device, cdev.kobj);
  93
  94         mutex_lock(&videodev_lock);
  95         if (video_device[vfd->minor] != vfd) {
  96                 mutex_unlock(&videodev_lock);
  97                 BUG();
  98                 return;
  99         }
 100
 101         /* Free up this device for reuse */
 102         video_device[vfd->minor] = NULL;
 103         clear_bit(vfd->num, video_nums[vfd->vfl_type]);
 104         mutex_unlock(&videodev_lock);
 105
 106         /* Release the character device */
 107         vfd->cdev_release(kobj);
 108         /* Release video_device and perform other
 109            cleanups as needed. */
 110         if (vfd->release)
 111                 vfd->release(vfd);
 112 }
 113
 114 /* The new kobj_type for the character device */
 115 static struct kobj_type v4l2_ktype_cdev_default = {
 116         .release = v4l2_chardev_release,
 117 };
 118
 119 static void video_release(struct device *cd)
 120 {
 121         struct video_device *vfd = container_of(cd, struct video_device, dev);
 122
 123         /* It's now safe to delete the char device.
 124            This will either trigger the v4l2_chardev_release immediately (if
 125            the refcount goes to 0) or later when the last user of the
 126            character device closes it. */
 127         cdev_del(&vfd->cdev);
 128 }
 129
 130 static struct class video_class = {
 131         .name = VIDEO_NAME,
 132         .dev_attrs = video_device_attrs,
 133         .dev_release = video_release,
 134 };
 135
 136 struct video_device *video_devdata(struct file *file)
 137 {
 138         return video_device[iminor(file->f_path.dentry->d_inode)];
 139 }
 140 EXPORT_SYMBOL(video_devdata);
 141
 142 /**
 143  * get_index - assign stream number based on parent device
 144  * @vdev: video_device to assign index number to, vdev->dev should be assigned
 145  * @num: -1 if auto assign, requested number otherwise
 146  *
 147  *
 148  * returns -ENFILE if num is already in use, a free index number if
 149  * successful.
 150  */
 151 static int get_index(struct video_device *vdev, int num)
 152 {
 153         u32 used = 0;
 154         const int max_index = sizeof(used) * 8 - 1;
 155         int i;
 156
 157         /* Currently a single v4l driver instance cannot create more than
 158            32 devices.
 159            Increase to u64 or an array of u32 if more are needed. */
 160         if (num > max_index) {
 161                 printk(KERN_ERR "videodev: %s num is too large\n", __func__);
 162                 return -EINVAL;
 163         }
 164
 165         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 166                 if (video_device[i] != NULL &&
 167                     video_device[i] != vdev &&
 168                     video_device[i]->parent == vdev->parent) {
 169                         used |= 1 << video_device[i]->index;
 170                 }
 171         }
 172
 173         if (num >= 0) {
 174                 if (used & (1 << num))
 175                         return -ENFILE;
 176                 return num;
 177         }
 178
 179         i = ffz(used);
 180         return i > max_index ? -ENFILE : i;
 181 }
 182
 183 static const struct file_operations video_fops;
 184
 185 int video_register_device(struct video_device *vfd, int type, int nr)
 186 {
 187         return video_register_device_index(vfd, type, nr, -1);
 188 }
 189 EXPORT_SYMBOL(video_register_device);
 190
 191 /**
 192  *      video_register_device_index - register video4linux devices
 193  *      @vfd:  video device structure we want to register
 194  *      @type: type of device to register
 195  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 196  *             -1 == first free)
 197  *      @index: stream number based on parent device;
 198  *              -1 if auto assign, requested number otherwise
 199  *
 200  *      The registration code assigns minor numbers based on the type
 201  *      requested. -ENFILE is returned in all the device slots for this
 202  *      category are full. If not then the minor field is set and the
 203  *      driver initialize function is called (if non %NULL).
 204  *
 205  *      Zero is returned on success.
 206  *
 207  *      Valid types are
 208  *
 209  *      %VFL_TYPE_GRABBER - A frame grabber
 210  *
 211  *      %VFL_TYPE_VTX - A teletext device
 212  *
 213  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 214  *
 215  *      %VFL_TYPE_RADIO - A radio card
 216  */
 217
 218 int video_register_device_index(struct video_device *vfd, int type, int nr,
 219                                         int index)
 220 {
 221         int i = 0;
 222         int ret;
 223         int minor_offset = 0;
 224         int minor_cnt = VIDEO_NUM_DEVICES;
 225         const char *name_base;
 226         void *priv = video_get_drvdata(vfd);
 227
 228         /* the release callback MUST be present */
 229         BUG_ON(!vfd->release);
 230
 231         if (vfd == NULL)
 232                 return -EINVAL;
 233
 234         switch (type) {
 235         case VFL_TYPE_GRABBER:
 236                 name_base = "video";
 237                 break;
 238         case VFL_TYPE_VTX:
 239                 name_base = "vtx";
 240                 break;
 241         case VFL_TYPE_VBI:
 242                 name_base = "vbi";
 243                 break;
 244         case VFL_TYPE_RADIO:
 245                 name_base = "radio";
 246                 break;
 247         default:
 248                 printk(KERN_ERR "%s called with unknown type: %d\n",
 249                        __func__, type);
 250                 return -EINVAL;
 251         }
 252
 253         vfd->vfl_type = type;
 254
 255 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 256         /* Keep the ranges for the first four types for historical
 257          * reasons.
 258          * Newer devices (not yet in place) should use the range
 259          * of 128-191 and just pick the first free minor there
 260          * (new style). */
 261         switch (type) {
 262         case VFL_TYPE_GRABBER:
 263                 minor_offset = 0;
 264                 minor_cnt = 64;
 265                 break;
 266         case VFL_TYPE_RADIO:
 267                 minor_offset = 64;
 268                 minor_cnt = 64;
 269                 break;
 270         case VFL_TYPE_VTX:
 271                 minor_offset = 192;
 272                 minor_cnt = 32;
 273                 break;
 274         case VFL_TYPE_VBI:
 275                 minor_offset = 224;
 276                 minor_cnt = 32;
 277                 break;
 278         default:
 279                 minor_offset = 128;
 280                 minor_cnt = 64;
 281                 break;
 282         }
 283 #endif
 284
 285         /* Initialize the character device */
 286         cdev_init(&vfd->cdev, vfd->fops);
 287         vfd->cdev.owner = vfd->fops->owner;
 288         /* pick a minor number */
 289         mutex_lock(&videodev_lock);
 290         nr = find_next_zero_bit(video_nums[type], minor_cnt, nr == -1 ? 0 : nr);
 291         if (nr == minor_cnt)
 292                 nr = find_first_zero_bit(video_nums[type], minor_cnt);
 293         if (nr == minor_cnt) {
 294                 printk(KERN_ERR "could not get a free kernel number\n");
 295                 mutex_unlock(&videodev_lock);
 296                 return -ENFILE;
 297         }
 298 #ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
 299         /* 1-on-1 mapping of kernel number to minor number */
 300         i = nr;
 301 #else
 302         /* The kernel number and minor numbers are independent */
 303         for (i = 0; i < VIDEO_NUM_DEVICES; i++)
 304                 if (video_device[i] == NULL)
 305                         break;
 306         if (i == VIDEO_NUM_DEVICES) {
 307                 mutex_unlock(&videodev_lock);
 308                 printk(KERN_ERR "could not get a free minor\n");
 309                 return -ENFILE;
 310         }
 311 #endif
 312         vfd->minor = i + minor_offset;
 313         vfd->num = nr;
 314         set_bit(nr, video_nums[type]);
 315         BUG_ON(video_device[vfd->minor]);
 316         video_device[vfd->minor] = vfd;
 317
 318         ret = get_index(vfd, index);
 319         vfd->index = ret;
 320
 321         mutex_unlock(&videodev_lock);
 322
 323         if (ret < 0) {
 324                 printk(KERN_ERR "%s: get_index failed\n", __func__);
 325                 goto fail_minor;
 326         }
 327
 328         ret = cdev_add(&vfd->cdev, MKDEV(VIDEO_MAJOR, vfd->minor), 1);
 329         if (ret < 0) {
 330                 printk(KERN_ERR "%s: cdev_add failed\n", __func__);
 331                 goto fail_minor;
 332         }
 333         /* sysfs class */
 334         memset(&vfd->dev, 0, sizeof(vfd->dev));
 335         /* The memset above cleared the device's drvdata, so
 336            put back the copy we made earlier. */
 337         video_set_drvdata(vfd, priv);
 338         vfd->dev.class = &video_class;
 339         vfd->dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
 340         if (vfd->parent)
 341                 vfd->dev.parent = vfd->parent;
 342         sprintf(vfd->dev.bus_id, "%s%d", name_base, nr);
 343         ret = device_register(&vfd->dev);
 344         if (ret < 0) {
 345                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 346                 goto del_cdev;
 347         }
 348         /* Remember the cdev's release function */
 349         vfd->cdev_release = vfd->cdev.kobj.ktype->release;
 350         /* Install our own */
 351         vfd->cdev.kobj.ktype = &v4l2_ktype_cdev_default;
 352         return 0;
 353
 354 del_cdev:
 355         cdev_del(&vfd->cdev);
 356
 357 fail_minor:
 358         mutex_lock(&videodev_lock);
 359         video_device[vfd->minor] = NULL;
 360         clear_bit(vfd->num, video_nums[type]);
 361         mutex_unlock(&videodev_lock);
 362         vfd->minor = -1;
 363         return ret;
 364 }
 365 EXPORT_SYMBOL(video_register_device_index);
 366
 367 /**
 368  *      video_unregister_device - unregister a video4linux device
 369  *      @vfd: the device to unregister
 370  *
 371  *      This unregisters the passed device and deassigns the minor
 372  *      number. Future open calls will be met with errors.
 373  */
 374
 375 void video_unregister_device(struct video_device *vfd)
 376 {
 377         device_unregister(&vfd->dev);
 378 }
 379 EXPORT_SYMBOL(video_unregister_device);
 380
 381 /*
 382  *      Initialise video for linux
 383  */
 384 static int __init videodev_init(void)
 385 {
 386         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 387         int ret;
 388
 389         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 390         ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
 391         if (ret < 0) {
 392                 printk(KERN_WARNING "videodev: unable to get major %d\n",
 393                                 VIDEO_MAJOR);
 394                 return ret;
 395         }
 396
 397         ret = class_register(&video_class);
 398         if (ret < 0) {
 399                 unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 400                 printk(KERN_WARNING "video_dev: class_register failed\n");
 401                 return -EIO;
 402         }
 403
 404         return 0;
 405 }
 406
 407 static void __exit videodev_exit(void)
 408 {
 409         dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 410
 411         class_unregister(&video_class);
 412         unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 413 }
 414
 415 module_init(videodev_init)
 416 module_exit(videodev_exit)
 417
 418 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 419 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 420 MODULE_LICENSE("GPL");
 421
 422
 423 /*
 424  * Local variables:
 425  * c-basic-offset: 8
 426  * End:
 427  */