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,
  45                                                 class_dev);
  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,
  53                                                 class_dev);
  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 struct video_device *video_device_alloc(void)
  64 {
  65         struct video_device *vfd;
  66
  67         vfd = kzalloc(sizeof(*vfd), GFP_KERNEL);
  68         return vfd;
  69 }
  70 EXPORT_SYMBOL(video_device_alloc);
  71
  72 void video_device_release(struct video_device *vfd)
  73 {
  74         kfree(vfd);
  75 }
  76 EXPORT_SYMBOL(video_device_release);
  77
  78 static void video_release(struct device *cd)
  79 {
  80         struct video_device *vfd = container_of(cd, struct video_device,
  81                                                                 class_dev);
  82
  83 #if 1
  84         /* needed until all drivers are fixed */
  85         if (!vfd->release)
  86                 return;
  87 #endif
  88         vfd->release(vfd);
  89 }
  90
  91 static struct class video_class = {
  92         .name = VIDEO_NAME,
  93         .dev_attrs = video_device_attrs,
  94         .dev_release = video_release,
  95 };
  96
  97 /*
  98  *      Active devices
  99  */
 100
 101 static struct video_device *video_device[VIDEO_NUM_DEVICES];
 102 static DEFINE_MUTEX(videodev_lock);
 103
 104 struct video_device *video_devdata(struct file *file)
 105 {
 106         return video_device[iminor(file->f_path.dentry->d_inode)];
 107 }
 108 EXPORT_SYMBOL(video_devdata);
 109
 110 /*
 111  *      Open a video device - FIXME: Obsoleted
 112  */
 113 static int video_open(struct inode *inode, struct file *file)
 114 {
 115         unsigned int minor = iminor(inode);
 116         int err = 0;
 117         struct video_device *vfl;
 118         const struct file_operations *old_fops;
 119
 120         if (minor >= VIDEO_NUM_DEVICES)
 121                 return -ENODEV;
 122         lock_kernel();
 123         mutex_lock(&videodev_lock);
 124         vfl = video_device[minor];
 125         if (vfl == NULL) {
 126                 mutex_unlock(&videodev_lock);
 127                 request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
 128                 mutex_lock(&videodev_lock);
 129                 vfl = video_device[minor];
 130                 if (vfl == NULL) {
 131                         mutex_unlock(&videodev_lock);
 132                         unlock_kernel();
 133                         return -ENODEV;
 134                 }
 135         }
 136         old_fops = file->f_op;
 137         file->f_op = fops_get(vfl->fops);
 138         if (file->f_op->open)
 139                 err = file->f_op->open(inode, file);
 140         if (err) {
 141                 fops_put(file->f_op);
 142                 file->f_op = fops_get(old_fops);
 143         }
 144         fops_put(old_fops);
 145         mutex_unlock(&videodev_lock);
 146         unlock_kernel();
 147         return err;
 148 }
 149
 150 /*
 151  * open/release helper functions -- handle exclusive opens
 152  * Should be removed soon
 153  */
 154 int video_exclusive_open(struct inode *inode, struct file *file)
 155 {
 156         struct video_device *vfl = video_devdata(file);
 157         int retval = 0;
 158
 159         mutex_lock(&vfl->lock);
 160         if (vfl->users)
 161                 retval = -EBUSY;
 162         else
 163                 vfl->users++;
 164         mutex_unlock(&vfl->lock);
 165         return retval;
 166 }
 167 EXPORT_SYMBOL(video_exclusive_open);
 168
 169 int video_exclusive_release(struct inode *inode, struct file *file)
 170 {
 171         struct video_device *vfl = video_devdata(file);
 172
 173         vfl->users--;
 174         return 0;
 175 }
 176 EXPORT_SYMBOL(video_exclusive_release);
 177
 178 /**
 179  * get_index - assign stream number based on parent device
 180  * @vdev: video_device to assign index number to, vdev->dev should be assigned
 181  * @num: -1 if auto assign, requested number otherwise
 182  *
 183  *
 184  * returns -ENFILE if num is already in use, a free index number if
 185  * successful.
 186  */
 187 static int get_index(struct video_device *vdev, int num)
 188 {
 189         u32 used = 0;
 190         const int max_index = sizeof(used) * 8 - 1;
 191         int i;
 192
 193         /* Currently a single v4l driver instance cannot create more than
 194            32 devices.
 195            Increase to u64 or an array of u32 if more are needed. */
 196         if (num > max_index) {
 197                 printk(KERN_ERR "videodev: %s num is too large\n", __func__);
 198                 return -EINVAL;
 199         }
 200
 201         for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
 202                 if (video_device[i] != NULL &&
 203                     video_device[i] != vdev &&
 204                     video_device[i]->dev == vdev->dev) {
 205                         used |= 1 << video_device[i]->index;
 206                 }
 207         }
 208
 209         if (num >= 0) {
 210                 if (used & (1 << num))
 211                         return -ENFILE;
 212                 return num;
 213         }
 214
 215         i = ffz(used);
 216         return i > max_index ? -ENFILE : i;
 217 }
 218
 219 static const struct file_operations video_fops;
 220
 221 int video_register_device(struct video_device *vfd, int type, int nr)
 222 {
 223         return video_register_device_index(vfd, type, nr, -1);
 224 }
 225 EXPORT_SYMBOL(video_register_device);
 226
 227 /**
 228  *      video_register_device - register video4linux devices
 229  *      @vfd:  video device structure we want to register
 230  *      @type: type of device to register
 231  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 232  *             -1 == first free)
 233  *
 234  *      The registration code assigns minor numbers based on the type
 235  *      requested. -ENFILE is returned in all the device slots for this
 236  *      category are full. If not then the minor field is set and the
 237  *      driver initialize function is called (if non %NULL).
 238  *
 239  *      Zero is returned on success.
 240  *
 241  *      Valid types are
 242  *
 243  *      %VFL_TYPE_GRABBER - A frame grabber
 244  *
 245  *      %VFL_TYPE_VTX - A teletext device
 246  *
 247  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 248  *
 249  *      %VFL_TYPE_RADIO - A radio card
 250  */
 251
 252 int video_register_device_index(struct video_device *vfd, int type, int nr,
 253                                         int index)
 254 {
 255         int i = 0;
 256         int base;
 257         int end;
 258         int ret;
 259         char *name_base;
 260
 261         switch (type) {
 262         case VFL_TYPE_GRABBER:
 263                 base = MINOR_VFL_TYPE_GRABBER_MIN;
 264                 end = MINOR_VFL_TYPE_GRABBER_MAX+1;
 265                 name_base = "video";
 266                 break;
 267         case VFL_TYPE_VTX:
 268                 base = MINOR_VFL_TYPE_VTX_MIN;
 269                 end = MINOR_VFL_TYPE_VTX_MAX+1;
 270                 name_base = "vtx";
 271                 break;
 272         case VFL_TYPE_VBI:
 273                 base = MINOR_VFL_TYPE_VBI_MIN;
 274                 end = MINOR_VFL_TYPE_VBI_MAX+1;
 275                 name_base = "vbi";
 276                 break;
 277         case VFL_TYPE_RADIO:
 278                 base = MINOR_VFL_TYPE_RADIO_MIN;
 279                 end = MINOR_VFL_TYPE_RADIO_MAX+1;
 280                 name_base = "radio";
 281                 break;
 282         default:
 283                 printk(KERN_ERR "%s called with unknown type: %d\n",
 284                        __func__, type);
 285                 return -1;
 286         }
 287
 288         /* pick a minor number */
 289         mutex_lock(&videodev_lock);
 290         if (nr >= 0  &&  nr < end-base) {
 291                 /* use the one the driver asked for */
 292                 i = base + nr;
 293                 if (NULL != video_device[i]) {
 294                         mutex_unlock(&videodev_lock);
 295                         return -ENFILE;
 296                 }
 297         } else {
 298                 /* use first free */
 299                 for (i = base; i < end; i++)
 300                         if (NULL == video_device[i])
 301                                 break;
 302                 if (i == end) {
 303                         mutex_unlock(&videodev_lock);
 304                         return -ENFILE;
 305                 }
 306         }
 307         video_device[i] = vfd;
 308         vfd->minor = i;
 309
 310         ret = get_index(vfd, index);
 311         vfd->index = ret;
 312
 313         mutex_unlock(&videodev_lock);
 314
 315         if (ret < 0) {
 316                 printk(KERN_ERR "%s: get_index failed\n", __func__);
 317                 goto fail_minor;
 318         }
 319
 320         mutex_init(&vfd->lock);
 321
 322         /* sysfs class */
 323         memset(&vfd->class_dev, 0x00, sizeof(vfd->class_dev));
 324         vfd->class_dev.class = &video_class;
 325         vfd->class_dev.devt = MKDEV(VIDEO_MAJOR, vfd->minor);
 326         if (vfd->dev)
 327                 vfd->class_dev.parent = vfd->dev;
 328         sprintf(vfd->class_dev.bus_id, "%s%d", name_base, i - base);
 329         ret = device_register(&vfd->class_dev);
 330         if (ret < 0) {
 331                 printk(KERN_ERR "%s: device_register failed\n", __func__);
 332                 goto fail_minor;
 333         }
 334
 335 #if 1
 336         /* needed until all drivers are fixed */
 337         if (!vfd->release)
 338                 printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
 339                        "Please fix your driver for proper sysfs support, see "
 340                        "http://lwn.net/Articles/36850/\n", vfd->name);
 341 #endif
 342         return 0;
 343
 344 fail_minor:
 345         mutex_lock(&videodev_lock);
 346         video_device[vfd->minor] = NULL;
 347         vfd->minor = -1;
 348         mutex_unlock(&videodev_lock);
 349         return ret;
 350 }
 351 EXPORT_SYMBOL(video_register_device_index);
 352
 353 /**
 354  *      video_unregister_device - unregister a video4linux device
 355  *      @vfd: the device to unregister
 356  *
 357  *      This unregisters the passed device and deassigns the minor
 358  *      number. Future open calls will be met with errors.
 359  */
 360
 361 void video_unregister_device(struct video_device *vfd)
 362 {
 363         mutex_lock(&videodev_lock);
 364         if (video_device[vfd->minor] != vfd)
 365                 panic("videodev: bad unregister");
 366
 367         video_device[vfd->minor] = NULL;
 368         device_unregister(&vfd->class_dev);
 369         mutex_unlock(&videodev_lock);
 370 }
 371 EXPORT_SYMBOL(video_unregister_device);
 372
 373 /*
 374  * Video fs operations
 375  */
 376 static const struct file_operations video_fops = {
 377         .owner          = THIS_MODULE,
 378         .llseek         = no_llseek,
 379         .open           = video_open,
 380 };
 381
 382 /*
 383  *      Initialise video for linux
 384  */
 385
 386 static int __init videodev_init(void)
 387 {
 388         int ret;
 389
 390         printk(KERN_INFO "Linux video capture interface: v2.00\n");
 391         if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
 392                 printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
 393                 return -EIO;
 394         }
 395
 396         ret = class_register(&video_class);
 397         if (ret < 0) {
 398                 unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 399                 printk(KERN_WARNING "video_dev: class_register failed\n");
 400                 return -EIO;
 401         }
 402
 403         return 0;
 404 }
 405
 406 static void __exit videodev_exit(void)
 407 {
 408         class_unregister(&video_class);
 409         unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 410 }
 411
 412 module_init(videodev_init)
 413 module_exit(videodev_exit)
 414
 415 MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
 416 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
 417 MODULE_LICENSE("GPL");
 418
 419
 420 /*
 421  * Local variables:
 422  * c-basic-offset: 8
 423  * End:
 424  */