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         return sprintf(buf, "%i\n", vfd->index);
  46 }
  47
  48 static ssize_t show_name(struct device *cd,
  49                          struct device_attribute *attr, char *buf)
  50 {
  51         struct video_device *vfd = container_of(cd, struct video_device, dev);
  52         return sprintf(buf, "%.*s\n", (int)sizeof(vfd->name), vfd->name);
  53 }
  54
  55 static struct device_attribute video_device_attrs[] = {
  56         __ATTR(name, S_IRUGO, show_name, NULL),
  57         __ATTR(index, S_IRUGO, show_index, NULL),
  58         __ATTR_NULL
  59 };
  60
  61 struct video_device *video_device_alloc(void)
  62 {
  63         struct video_device *vfd;
  64
  65         vfd = kzalloc(sizeof(*vfd), GFP_KERNEL);
  66         return vfd;
  67 }
  68 EXPORT_SYMBOL(video_device_alloc);
  69
  70 void video_device_release(struct video_device *vfd)
  71 {
  72         kfree(vfd);
  73 }
  74 EXPORT_SYMBOL(video_device_release);
  75
  76 static void video_release(struct device *cd)
  77 {
  78         struct video_device *vfd = container_of(cd, struct video_device, dev);
  79
  80 #if 1
  81         /* needed until all drivers are fixed */
  82         if (!vfd->release)
  83                 return;
  84 #endif
  85         vfd->release(vfd);
  86 }
  87
  88 static struct class video_class = {
  89         .name = VIDEO_NAME,
  90         .dev_attrs = video_device_attrs,
  91         .dev_release = video_release,
  92 };
  93
  94 /*
  95  *      Active devices
  96  */
  97
  98 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  99 static DEFINE_MUTEX(videodev_lock);
 100
 101 struct video_device *video_devdata(struct file *file)
 102 {
 103         return video_device[iminor(file->f_path.dentry->d_inode)];
 104 }
 105 EXPORT_SYMBOL(video_devdata);
 106
 107 /*
 108  *      Open a video device - FIXME: Obsoleted
 109  */
 110 static int video_open(struct inode *inode, struct file *file)
 111 {
 112         unsigned int minor = iminor(inode);
 113         int err = 0;
 114         struct video_device *vfl;
 115         const struct file_operations *old_fops;
 116
 117         if (minor >= VIDEO_NUM_DEVICES)
 118                 return -ENODEV;
 119         lock_kernel();
 120         mutex_lock(&videodev_lock);
 121         vfl = video_device[minor];
 122         if (vfl == NULL) {
 123                 mutex_unlock(&videodev_lock);
 124                 request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
 125                 mutex_lock(&videodev_lock);
 126                 vfl = video_device[minor];
 127                 if (vfl == NULL) {
 128                         mutex_unlock(&videodev_lock);
 129                         unlock_kernel();
 130                         return -ENODEV;
 131                 }
 132         }
 133         old_fops = file->f_op;
 134         file->f_op = fops_get(vfl->fops);
 135         if (file->f_op->open)
 136                 err = file->f_op->open(inode, file);
 137         if (err) {
 138                 fops_put(file->f_op);
 139                 file->f_op = fops_get(old_fops);
 140         }
 141         fops_put(old_fops);
 142         mutex_unlock(&videodev_lock);
 143         unlock_kernel();
 144         return err;
 145 }
 146
 147 /*
 148  * open/release helper functions -- handle exclusive opens
 149  * Should be removed soon
 150  */
 151 int video_exclusive_open(struct inode *inode, struct file *file)
 152 {
 153         struct video_device *vfl = video_devdata(file);
 154         int retval = 0;
 155
 156         mutex_lock(&vfl->lock);
 157         if (vfl->users)
 158                 retval = -EBUSY;
 159         else
 160                 vfl->users++;
 161         mutex_unlock(&vfl->lock);
 162         return retval;
 163 }
 164 EXPORT_SYMBOL(video_exclusive_open);
 165
 166 int video_exclusive_release(struct inode *inode, struct file *file)
 167 {
 168         struct video_device *vfl = video_devdata(file);
 169
 170         vfl->users--;
 171         return 0;
 172 }
 173 EXPORT_SYMBOL(video_exclusive_release);
 174
 175 /**
 176  * get_index - assign stream number based on parent device
 177  * @vdev: video_device to assign index number to, vdev->dev should be assigned
 178  * @num: -1 if auto assign, requested number otherwise
 179  *
 180  *
 181  * returns -ENFILE if num is already in use, a free index number if
 182  * successful.
 183  */
 184 static int get_index(struct video_device *vdev, int num)
 185 {
 186         u32 used = 0;
 187         const int max_index = sizeof(used) * 8 - 1;
 188         int i;
 189
 190         /* Currently a single v4l driver instance cannot create more than
 191            32 devices.
 192            Increase to u64 or an array of u32 if more are needed. */
 193         if (num > max_index) {
 194                 printk(KERN_ERR "videodev: %s num is too large\n", __func__);
 195                 return -EINVAL;
 196         }
 197
 198         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 199                 if (video_device[i] != NULL &&
 200                     video_device[i] != vdev &&
 201                     video_device[i]->parent == vdev->parent) {
 202                         used |= 1 << video_device[i]->index;
 203                 }
 204         }
 205
 206         if (num >= 0) {
 207                 if (used & (1 << num))
 208                         return -ENFILE;
 209                 return num;
 210         }
 211
 212         i = ffz(used);
 213         return i > max_index ? -ENFILE : i;
 214 }
 215
 216 static const struct file_operations video_fops;
 217
 218 int video_register_device(struct video_device *vfd, int type, int nr)
 219 {
 220         return video_register_device_index(vfd, type, nr, -1);
 221 }
 222 EXPORT_SYMBOL(video_register_device);
 223
 224 /**
 225  *      video_register_device_index - register video4linux devices
 226  *      @vfd:  video device structure we want to register
 227  *      @type: type of device to register
 228  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 229  *             -1 == first free)
 230  *      @index: stream number based on parent device;
 231  *              -1 if auto assign, requested number otherwise
 232  *
 233  *      The registration code assigns minor numbers based on the type
 234  *      requested. -ENFILE is returned in all the device slots for this
 235  *      category are full. If not then the minor field is set and the
 236  *      driver initialize function is called (if non %NULL).
 237  *
 238  *      Zero is returned on success.
 239  *
 240  *      Valid types are
 241  *
 242  *      %VFL_TYPE_GRABBER - A frame grabber
 243  *
 244  *      %VFL_TYPE_VTX - A teletext device
 245  *
 246  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 247  *
 248  *      %VFL_TYPE_RADIO - A radio card
 249  */
 250
 251 int video_register_device_index(struct video_device *vfd, int type, int nr,
 252                                         int index)
 253 {
 254         int i = 0;
 255         int base;
 256         int end;
 257         int ret;
 258         char *name_base;
 259
 260         if (vfd == NULL)
 261                 return -EINVAL;
 262
 263         switch (type) {
 264         case VFL_TYPE_GRABBER:
 265                 base = MINOR_VFL_TYPE_GRABBER_MIN;
 266                 end = MINOR_VFL_TYPE_GRABBER_MAX+1;
 267                 name_base = "video";
 268                 break;
 269         case VFL_TYPE_VTX:
 270                 base = MINOR_VFL_TYPE_VTX_MIN;
 271                 end = MINOR_VFL_TYPE_VTX_MAX+1;
 272                 name_base = "vtx";
 273                 break;
 274         case VFL_TYPE_VBI:
 275                 base = MINOR_VFL_TYPE_VBI_MIN;
 276                 end = MINOR_VFL_TYPE_VBI_MAX+1;
 277                 name_base = "vbi";
 278                 break;
 279         case VFL_TYPE_RADIO:
 280                 base = MINOR_VFL_TYPE_RADIO_MIN;
 281                 end = MINOR_VFL_TYPE_RADIO_MAX+1;
 282                 name_base = "radio";
 283                 break;
 284         default:
 285                 printk(KERN_ERR "%s called with unknown type: %d\n",
 286                        __func__, type);
 287                 return -EINVAL;
 288         }
 289
 290         /* pick a minor number */
 291         mutex_lock(&videodev_lock);
 292         if (nr >= 0  &&  nr < end-base) {
 293                 /* use the one the driver asked for */
 294                 i = base + nr;
 295                 if (NULL != video_device[i]) {
 296                         mutex_unlock(&videodev_lock);
 297                         return -ENFILE;
 298                 }
 299         } else {
 300                 /* use first free */
 301                 for (i = base; i < end; i++)
 302                         if (NULL == video_device[i])
 303                                 break;
 304                 if (i == end) {
 305                         mutex_unlock(&videodev_lock);
 306                         return -ENFILE;
 307                 }
 308         }
 309         video_device[i] = vfd;
 310         vfd->vfl_type = type;
 311         vfd->minor = i;
 312
 313         ret = get_index(vfd, index);
 314         vfd->index = ret;
 315
 316         mutex_unlock(&videodev_lock);
 317
 318         if (ret < 0) {
 319                 printk(KERN_ERR "%s: get_index failed\n", __func__);
 320                 goto fail_minor;
 321         }
 322
 323         mutex_init(&vfd->lock);
 324
 325         /* sysfs class */
 326         memset(&vfd->dev, 0x00, sizeof(vfd->dev));
 327         vfd->dev.class = &video_class;
 328         vfd->dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
 329         if (vfd->parent)
 330                 vfd->dev.parent = vfd->parent;
 331         sprintf(vfd->dev.bus_id, "%s%d", name_base, i - base);
 332         ret = device_register(&vfd->dev);
 333         if (ret < 0) {
 334                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 335                 goto fail_minor;
 336         }
 337
 338 #if 1
 339         /* needed until all drivers are fixed */
 340         if (!vfd->release)
 341                 printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
 342                        "Please fix your driver for proper sysfs support, see "
 343                        "http://lwn.net/Articles/36850/\n", vfd->name);
 344 #endif
 345         return 0;
 346
 347 fail_minor:
 348         mutex_lock(&videodev_lock);
 349         video_device[vfd->minor] = NULL;
 350         vfd->minor = -1;
 351         mutex_unlock(&videodev_lock);
 352         return ret;
 353 }
 354 EXPORT_SYMBOL(video_register_device_index);
 355
 356 /**
 357  *      video_unregister_device - unregister a video4linux device
 358  *      @vfd: the device to unregister
 359  *
 360  *      This unregisters the passed device and deassigns the minor
 361  *      number. Future open calls will be met with errors.
 362  */
 363
 364 void video_unregister_device(struct video_device *vfd)
 365 {
 366         mutex_lock(&videodev_lock);
 367         if (video_device[vfd->minor] != vfd)
 368                 panic("videodev: bad unregister");
 369
 370         video_device[vfd->minor] = NULL;
 371         device_unregister(&vfd->dev);
 372         mutex_unlock(&videodev_lock);
 373 }
 374 EXPORT_SYMBOL(video_unregister_device);
 375
 376 /*
 377  * Video fs operations
 378  */
 379 static const struct file_operations video_fops = {
 380         .owner          = THIS_MODULE,
 381         .llseek         = no_llseek,
 382         .open           = video_open,
 383 };
 384
 385 /*
 386  *      Initialise video for linux
 387  */
 388
 389 static int __init videodev_init(void)
 390 {
 391         int ret;
 392
 393         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 394         if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
 395                 printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
 396                 return -EIO;
 397         }
 398
 399         ret = class_register(&video_class);
 400         if (ret < 0) {
 401                 unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 402                 printk(KERN_WARNING "video_dev: class_register failed\n");
 403                 return -EIO;
 404         }
 405
 406         return 0;
 407 }
 408
 409 static void __exit videodev_exit(void)
 410 {
 411         class_unregister(&video_class);
 412         unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 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  */