drivers/media/video/videodev.c

   1 /*
   2  * Video capture interface for Linux
   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  * Author:      Alan Cox, <alan@redhat.com>
  13  *
  14  * Fixes:       20000516  Claudio Matsuoka <claudio@conectiva.com>
  15  *              - Added procfs support
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/sched.h>
  22 #include <linux/smp_lock.h>
  23 #include <linux/mm.h>
  24 #include <linux/string.h>
  25 #include <linux/errno.h>
  26 #include <linux/init.h>
  27 #include <linux/kmod.h>
  28 #include <linux/slab.h>
  29 #include <linux/devfs_fs_kernel.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/system.h>
  32
  33 #include <linux/videodev.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_name(struct class_device *cd, char *buf)
  43 {
  44         struct video_device *vfd = container_of(cd, struct video_device, class_dev);
  45         return sprintf(buf,"%.*s\n",(int)sizeof(vfd->name),vfd->name);
  46 }
  47
  48 static CLASS_DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  49
  50 struct video_device *video_device_alloc(void)
  51 {
  52         struct video_device *vfd;
  53
  54         vfd = kzalloc(sizeof(*vfd),GFP_KERNEL);
  55         return vfd;
  56 }
  57
  58 void video_device_release(struct video_device *vfd)
  59 {
  60         kfree(vfd);
  61 }
  62
  63 static void video_release(struct class_device *cd)
  64 {
  65         struct video_device *vfd = container_of(cd, struct video_device, class_dev);
  66
  67 #if 1
  68         /* needed until all drivers are fixed */
  69         if (!vfd->release)
  70                 return;
  71 #endif
  72         vfd->release(vfd);
  73 }
  74
  75 static struct class video_class = {
  76         .name    = VIDEO_NAME,
  77         .release = video_release,
  78 };
  79
  80 /*
  81  *      Active devices
  82  */
  83
  84 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  85 static DEFINE_MUTEX(videodev_lock);
  86
  87 struct video_device* video_devdata(struct file *file)
  88 {
  89         return video_device[iminor(file->f_dentry->d_inode)];
  90 }
  91
  92 /*
  93  *      Open a video device.
  94  */
  95 static int video_open(struct inode *inode, struct file *file)
  96 {
  97         unsigned int minor = iminor(inode);
  98         int err = 0;
  99         struct video_device *vfl;
 100         const struct file_operations *old_fops;
 101
 102         if(minor>=VIDEO_NUM_DEVICES)
 103                 return -ENODEV;
 104         mutex_lock(&videodev_lock);
 105         vfl=video_device[minor];
 106         if(vfl==NULL) {
 107                 mutex_unlock(&videodev_lock);
 108                 request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
 109                 mutex_lock(&videodev_lock);
 110                 vfl=video_device[minor];
 111                 if (vfl==NULL) {
 112                         mutex_unlock(&videodev_lock);
 113                         return -ENODEV;
 114                 }
 115         }
 116         old_fops = file->f_op;
 117         file->f_op = fops_get(vfl->fops);
 118         if(file->f_op->open)
 119                 err = file->f_op->open(inode,file);
 120         if (err) {
 121                 fops_put(file->f_op);
 122                 file->f_op = fops_get(old_fops);
 123         }
 124         fops_put(old_fops);
 125         mutex_unlock(&videodev_lock);
 126         return err;
 127 }
 128
 129 /*
 130  * helper function -- handles userspace copying for ioctl arguments
 131  */
 132
 133 static unsigned int
 134 video_fix_command(unsigned int cmd)
 135 {
 136         switch (cmd) {
 137         case VIDIOC_OVERLAY_OLD:
 138                 cmd = VIDIOC_OVERLAY;
 139                 break;
 140         case VIDIOC_S_PARM_OLD:
 141                 cmd = VIDIOC_S_PARM;
 142                 break;
 143         case VIDIOC_S_CTRL_OLD:
 144                 cmd = VIDIOC_S_CTRL;
 145                 break;
 146         case VIDIOC_G_AUDIO_OLD:
 147                 cmd = VIDIOC_G_AUDIO;
 148                 break;
 149         case VIDIOC_G_AUDOUT_OLD:
 150                 cmd = VIDIOC_G_AUDOUT;
 151                 break;
 152         case VIDIOC_CROPCAP_OLD:
 153                 cmd = VIDIOC_CROPCAP;
 154                 break;
 155         }
 156         return cmd;
 157 }
 158
 159 int
 160 video_usercopy(struct inode *inode, struct file *file,
 161                unsigned int cmd, unsigned long arg,
 162                int (*func)(struct inode *inode, struct file *file,
 163                            unsigned int cmd, void *arg))
 164 {
 165         char    sbuf[128];
 166         void    *mbuf = NULL;
 167         void    *parg = NULL;
 168         int     err  = -EINVAL;
 169
 170         cmd = video_fix_command(cmd);
 171
 172         /*  Copy arguments into temp kernel buffer  */
 173         switch (_IOC_DIR(cmd)) {
 174         case _IOC_NONE:
 175                 parg = NULL;
 176                 break;
 177         case _IOC_READ:
 178         case _IOC_WRITE:
 179         case (_IOC_WRITE | _IOC_READ):
 180                 if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
 181                         parg = sbuf;
 182                 } else {
 183                         /* too big to allocate from stack */
 184                         mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
 185                         if (NULL == mbuf)
 186                                 return -ENOMEM;
 187                         parg = mbuf;
 188                 }
 189
 190                 err = -EFAULT;
 191                 if (_IOC_DIR(cmd) & _IOC_WRITE)
 192                         if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
 193                                 goto out;
 194                 break;
 195         }
 196
 197         /* call driver */
 198         err = func(inode, file, cmd, parg);
 199         if (err == -ENOIOCTLCMD)
 200                 err = -EINVAL;
 201         if (err < 0)
 202                 goto out;
 203
 204         /*  Copy results into user buffer  */
 205         switch (_IOC_DIR(cmd))
 206         {
 207         case _IOC_READ:
 208         case (_IOC_WRITE | _IOC_READ):
 209                 if (copy_to_user((void __user *)arg, parg, _IOC_SIZE(cmd)))
 210                         err = -EFAULT;
 211                 break;
 212         }
 213
 214 out:
 215         kfree(mbuf);
 216         return err;
 217 }
 218
 219 /*
 220  * open/release helper functions -- handle exclusive opens
 221  */
 222 int video_exclusive_open(struct inode *inode, struct file *file)
 223 {
 224         struct  video_device *vfl = video_devdata(file);
 225         int retval = 0;
 226
 227         mutex_lock(&vfl->lock);
 228         if (vfl->users) {
 229                 retval = -EBUSY;
 230         } else {
 231                 vfl->users++;
 232         }
 233         mutex_unlock(&vfl->lock);
 234         return retval;
 235 }
 236
 237 int video_exclusive_release(struct inode *inode, struct file *file)
 238 {
 239         struct  video_device *vfl = video_devdata(file);
 240
 241         vfl->users--;
 242         return 0;
 243 }
 244
 245 static struct file_operations video_fops;
 246
 247 /**
 248  *      video_register_device - register video4linux devices
 249  *      @vfd:  video device structure we want to register
 250  *      @type: type of device to register
 251  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 252  *             -1 == first free)
 253  *
 254  *      The registration code assigns minor numbers based on the type
 255  *      requested. -ENFILE is returned in all the device slots for this
 256  *      category are full. If not then the minor field is set and the
 257  *      driver initialize function is called (if non %NULL).
 258  *
 259  *      Zero is returned on success.
 260  *
 261  *      Valid types are
 262  *
 263  *      %VFL_TYPE_GRABBER - A frame grabber
 264  *
 265  *      %VFL_TYPE_VTX - A teletext device
 266  *
 267  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 268  *
 269  *      %VFL_TYPE_RADIO - A radio card
 270  */
 271
 272 int video_register_device(struct video_device *vfd, int type, int nr)
 273 {
 274         int i=0;
 275         int base;
 276         int end;
 277         char *name_base;
 278
 279         switch(type)
 280         {
 281                 case VFL_TYPE_GRABBER:
 282                         base=MINOR_VFL_TYPE_GRABBER_MIN;
 283                         end=MINOR_VFL_TYPE_GRABBER_MAX+1;
 284                         name_base = "video";
 285                         break;
 286                 case VFL_TYPE_VTX:
 287                         base=MINOR_VFL_TYPE_VTX_MIN;
 288                         end=MINOR_VFL_TYPE_VTX_MAX+1;
 289                         name_base = "vtx";
 290                         break;
 291                 case VFL_TYPE_VBI:
 292                         base=MINOR_VFL_TYPE_VBI_MIN;
 293                         end=MINOR_VFL_TYPE_VBI_MAX+1;
 294                         name_base = "vbi";
 295                         break;
 296                 case VFL_TYPE_RADIO:
 297                         base=MINOR_VFL_TYPE_RADIO_MIN;
 298                         end=MINOR_VFL_TYPE_RADIO_MAX+1;
 299                         name_base = "radio";
 300                         break;
 301                 default:
 302                         return -1;
 303         }
 304
 305         /* pick a minor number */
 306         mutex_lock(&videodev_lock);
 307         if (nr >= 0  &&  nr < end-base) {
 308                 /* use the one the driver asked for */
 309                 i = base+nr;
 310                 if (NULL != video_device[i]) {
 311                         mutex_unlock(&videodev_lock);
 312                         return -ENFILE;
 313                 }
 314         } else {
 315                 /* use first free */
 316                 for(i=base;i<end;i++)
 317                         if (NULL == video_device[i])
 318                                 break;
 319                 if (i == end) {
 320                         mutex_unlock(&videodev_lock);
 321                         return -ENFILE;
 322                 }
 323         }
 324         video_device[i]=vfd;
 325         vfd->minor=i;
 326         mutex_unlock(&videodev_lock);
 327
 328         sprintf(vfd->devfs_name, "v4l/%s%d", name_base, i - base);
 329         devfs_mk_cdev(MKDEV(VIDEO_MAJOR, vfd->minor),
 330                         S_IFCHR | S_IRUSR | S_IWUSR, vfd->devfs_name);
 331         mutex_init(&vfd->lock);
 332
 333         /* sysfs class */
 334         memset(&vfd->class_dev, 0x00, sizeof(vfd->class_dev));
 335         if (vfd->dev)
 336                 vfd->class_dev.dev = vfd->dev;
 337         vfd->class_dev.class       = &video_class;
 338         vfd->class_dev.devt        = MKDEV(VIDEO_MAJOR, vfd->minor);
 339         strlcpy(vfd->class_dev.class_id, vfd->devfs_name + 4, BUS_ID_SIZE);
 340         class_device_register(&vfd->class_dev);
 341         class_device_create_file(&vfd->class_dev,
 342                                 &class_device_attr_name);
 343
 344 #if 1
 345         /* needed until all drivers are fixed */
 346         if (!vfd->release)
 347                 printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
 348                        "Please fix your driver for proper sysfs support, see "
 349                        "http://lwn.net/Articles/36850/\n", vfd->name);
 350 #endif
 351         return 0;
 352 }
 353
 354 /**
 355  *      video_unregister_device - unregister a video4linux device
 356  *      @vfd: the device to unregister
 357  *
 358  *      This unregisters the passed device and deassigns the minor
 359  *      number. Future open calls will be met with errors.
 360  */
 361
 362 void video_unregister_device(struct video_device *vfd)
 363 {
 364         mutex_lock(&videodev_lock);
 365         if(video_device[vfd->minor]!=vfd)
 366                 panic("videodev: bad unregister");
 367
 368         devfs_remove(vfd->devfs_name);
 369         video_device[vfd->minor]=NULL;
 370         class_device_unregister(&vfd->class_dev);
 371         mutex_unlock(&videodev_lock);
 372 }
 373
 374
 375 static struct file_operations video_fops=
 376 {
 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: v1.00\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 EXPORT_SYMBOL(video_register_device);
 416 EXPORT_SYMBOL(video_unregister_device);
 417 EXPORT_SYMBOL(video_devdata);
 418 EXPORT_SYMBOL(video_usercopy);
 419 EXPORT_SYMBOL(video_exclusive_open);
 420 EXPORT_SYMBOL(video_exclusive_release);
 421 EXPORT_SYMBOL(video_device_alloc);
 422 EXPORT_SYMBOL(video_device_release);
 423
 424 MODULE_AUTHOR("Alan Cox");
 425 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers");
 426 MODULE_LICENSE("GPL");
 427
 428
 429 /*
 430  * Local variables:
 431  * c-basic-offset: 8
 432  * End:
 433  */