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 #include <asm/semaphore.h>
  33
  34 #include <linux/videodev.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_name(struct class_device *cd, char *buf)
  44 {
  45         struct video_device *vfd = container_of(cd, struct video_device, class_dev);
  46         return sprintf(buf,"%.*s\n",(int)sizeof(vfd->name),vfd->name);
  47 }
  48
  49 static CLASS_DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  50
  51 struct video_device *video_device_alloc(void)
  52 {
  53         struct video_device *vfd;
  54
  55         vfd = kzalloc(sizeof(*vfd),GFP_KERNEL);
  56         return vfd;
  57 }
  58
  59 void video_device_release(struct video_device *vfd)
  60 {
  61         kfree(vfd);
  62 }
  63
  64 static void video_release(struct class_device *cd)
  65 {
  66         struct video_device *vfd = container_of(cd, struct video_device, class_dev);
  67
  68 #if 1
  69         /* needed until all drivers are fixed */
  70         if (!vfd->release)
  71                 return;
  72 #endif
  73         vfd->release(vfd);
  74 }
  75
  76 static struct class video_class = {
  77         .name    = VIDEO_NAME,
  78         .release = video_release,
  79 };
  80
  81 /*
  82  *      Active devices
  83  */
  84
  85 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  86 static DECLARE_MUTEX(videodev_lock);
  87
  88 struct video_device* video_devdata(struct file *file)
  89 {
  90         return video_device[iminor(file->f_dentry->d_inode)];
  91 }
  92
  93 /*
  94  *      Open a video device.
  95  */
  96 static int video_open(struct inode *inode, struct file *file)
  97 {
  98         unsigned int minor = iminor(inode);
  99         int err = 0;
 100         struct video_device *vfl;
 101         struct file_operations *old_fops;
 102
 103         if(minor>=VIDEO_NUM_DEVICES)
 104                 return -ENODEV;
 105         down(&videodev_lock);
 106         vfl=video_device[minor];
 107         if(vfl==NULL) {
 108                 up(&videodev_lock);
 109                 request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
 110                 down(&videodev_lock);
 111                 vfl=video_device[minor];
 112                 if (vfl==NULL) {
 113                         up(&videodev_lock);
 114                         return -ENODEV;
 115                 }
 116         }
 117         old_fops = file->f_op;
 118         file->f_op = fops_get(vfl->fops);
 119         if(file->f_op->open)
 120                 err = file->f_op->open(inode,file);
 121         if (err) {
 122                 fops_put(file->f_op);
 123                 file->f_op = fops_get(old_fops);
 124         }
 125         fops_put(old_fops);
 126         up(&videodev_lock);
 127         return err;
 128 }
 129
 130 /*
 131  * helper function -- handles userspace copying for ioctl arguments
 132  */
 133
 134 static unsigned int
 135 video_fix_command(unsigned int cmd)
 136 {
 137         switch (cmd) {
 138         case VIDIOC_OVERLAY_OLD:
 139                 cmd = VIDIOC_OVERLAY;
 140                 break;
 141         case VIDIOC_S_PARM_OLD:
 142                 cmd = VIDIOC_S_PARM;
 143                 break;
 144         case VIDIOC_S_CTRL_OLD:
 145                 cmd = VIDIOC_S_CTRL;
 146                 break;
 147         case VIDIOC_G_AUDIO_OLD:
 148                 cmd = VIDIOC_G_AUDIO;
 149                 break;
 150         case VIDIOC_G_AUDOUT_OLD:
 151                 cmd = VIDIOC_G_AUDOUT;
 152                 break;
 153         case VIDIOC_CROPCAP_OLD:
 154                 cmd = VIDIOC_CROPCAP;
 155                 break;
 156         }
 157         return cmd;
 158 }
 159
 160 int
 161 video_usercopy(struct inode *inode, struct file *file,
 162                unsigned int cmd, unsigned long arg,
 163                int (*func)(struct inode *inode, struct file *file,
 164                            unsigned int cmd, void *arg))
 165 {
 166         char    sbuf[128];
 167         void    *mbuf = NULL;
 168         void    *parg = NULL;
 169         int     err  = -EINVAL;
 170
 171         cmd = video_fix_command(cmd);
 172
 173         /*  Copy arguments into temp kernel buffer  */
 174         switch (_IOC_DIR(cmd)) {
 175         case _IOC_NONE:
 176                 parg = NULL;
 177                 break;
 178         case _IOC_READ:
 179         case _IOC_WRITE:
 180         case (_IOC_WRITE | _IOC_READ):
 181                 if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
 182                         parg = sbuf;
 183                 } else {
 184                         /* too big to allocate from stack */
 185                         mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
 186                         if (NULL == mbuf)
 187                                 return -ENOMEM;
 188                         parg = mbuf;
 189                 }
 190
 191                 err = -EFAULT;
 192                 if (_IOC_DIR(cmd) & _IOC_WRITE)
 193                         if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
 194                                 goto out;
 195                 break;
 196         }
 197
 198         /* call driver */
 199         err = func(inode, file, cmd, parg);
 200         if (err == -ENOIOCTLCMD)
 201                 err = -EINVAL;
 202         if (err < 0)
 203                 goto out;
 204
 205         /*  Copy results into user buffer  */
 206         switch (_IOC_DIR(cmd))
 207         {
 208         case _IOC_READ:
 209         case (_IOC_WRITE | _IOC_READ):
 210                 if (copy_to_user((void __user *)arg, parg, _IOC_SIZE(cmd)))
 211                         err = -EFAULT;
 212                 break;
 213         }
 214
 215 out:
 216         kfree(mbuf);
 217         return err;
 218 }
 219
 220 /*
 221  * open/release helper functions -- handle exclusive opens
 222  */
 223 int video_exclusive_open(struct inode *inode, struct file *file)
 224 {
 225         struct  video_device *vfl = video_devdata(file);
 226         int retval = 0;
 227
 228         down(&vfl->lock);
 229         if (vfl->users) {
 230                 retval = -EBUSY;
 231         } else {
 232                 vfl->users++;
 233         }
 234         up(&vfl->lock);
 235         return retval;
 236 }
 237
 238 int video_exclusive_release(struct inode *inode, struct file *file)
 239 {
 240         struct  video_device *vfl = video_devdata(file);
 241
 242         vfl->users--;
 243         return 0;
 244 }
 245
 246 static struct file_operations video_fops;
 247
 248 /**
 249  *      video_register_device - register video4linux devices
 250  *      @vfd:  video device structure we want to register
 251  *      @type: type of device to register
 252  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 253  *             -1 == first free)
 254  *
 255  *      The registration code assigns minor numbers based on the type
 256  *      requested. -ENFILE is returned in all the device slots for this
 257  *      category are full. If not then the minor field is set and the
 258  *      driver initialize function is called (if non %NULL).
 259  *
 260  *      Zero is returned on success.
 261  *
 262  *      Valid types are
 263  *
 264  *      %VFL_TYPE_GRABBER - A frame grabber
 265  *
 266  *      %VFL_TYPE_VTX - A teletext device
 267  *
 268  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 269  *
 270  *      %VFL_TYPE_RADIO - A radio card
 271  */
 272
 273 int video_register_device(struct video_device *vfd, int type, int nr)
 274 {
 275         int i=0;
 276         int base;
 277         int end;
 278         char *name_base;
 279
 280         switch(type)
 281         {
 282                 case VFL_TYPE_GRABBER:
 283                         base=0;
 284                         end=64;
 285                         name_base = "video";
 286                         break;
 287                 case VFL_TYPE_VTX:
 288                         base=192;
 289                         end=224;
 290                         name_base = "vtx";
 291                         break;
 292                 case VFL_TYPE_VBI:
 293                         base=224;
 294                         end=256;
 295                         name_base = "vbi";
 296                         break;
 297                 case VFL_TYPE_RADIO:
 298                         base=64;
 299                         end=128;
 300                         name_base = "radio";
 301                         break;
 302                 default:
 303                         return -1;
 304         }
 305
 306         /* pick a minor number */
 307         down(&videodev_lock);
 308         if (nr >= 0  &&  nr < end-base) {
 309                 /* use the one the driver asked for */
 310                 i = base+nr;
 311                 if (NULL != video_device[i]) {
 312                         up(&videodev_lock);
 313                         return -ENFILE;
 314                 }
 315         } else {
 316                 /* use first free */
 317                 for(i=base;i<end;i++)
 318                         if (NULL == video_device[i])
 319                                 break;
 320                 if (i == end) {
 321                         up(&videodev_lock);
 322                         return -ENFILE;
 323                 }
 324         }
 325         video_device[i]=vfd;
 326         vfd->minor=i;
 327         up(&videodev_lock);
 328
 329         sprintf(vfd->devfs_name, "v4l/%s%d", name_base, i - base);
 330         devfs_mk_cdev(MKDEV(VIDEO_MAJOR, vfd->minor),
 331                         S_IFCHR | S_IRUSR | S_IWUSR, vfd->devfs_name);
 332         init_MUTEX(&vfd->lock);
 333
 334         /* sysfs class */
 335         memset(&vfd->class_dev, 0x00, sizeof(vfd->class_dev));
 336         if (vfd->dev)
 337                 vfd->class_dev.dev = vfd->dev;
 338         vfd->class_dev.class       = &video_class;
 339         vfd->class_dev.devt        = MKDEV(VIDEO_MAJOR, vfd->minor);
 340         strlcpy(vfd->class_dev.class_id, vfd->devfs_name + 4, BUS_ID_SIZE);
 341         class_device_register(&vfd->class_dev);
 342         class_device_create_file(&vfd->class_dev,
 343                                 &class_device_attr_name);
 344
 345 #if 1
 346         /* needed until all drivers are fixed */
 347         if (!vfd->release)
 348                 printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
 349                        "Please fix your driver for proper sysfs support, see "
 350                        "http://lwn.net/Articles/36850/\n", vfd->name);
 351 #endif
 352         return 0;
 353 }
 354
 355 /**
 356  *      video_unregister_device - unregister a video4linux device
 357  *      @vfd: the device to unregister
 358  *
 359  *      This unregisters the passed device and deassigns the minor
 360  *      number. Future open calls will be met with errors.
 361  */
 362
 363 void video_unregister_device(struct video_device *vfd)
 364 {
 365         down(&videodev_lock);
 366         if(video_device[vfd->minor]!=vfd)
 367                 panic("videodev: bad unregister");
 368
 369         devfs_remove(vfd->devfs_name);
 370         video_device[vfd->minor]=NULL;
 371         class_device_unregister(&vfd->class_dev);
 372         up(&videodev_lock);
 373 }
 374
 375
 376 static struct file_operations video_fops=
 377 {
 378         .owner          = THIS_MODULE,
 379         .llseek         = no_llseek,
 380         .open           = video_open,
 381 };
 382
 383 /*
 384  *      Initialise video for linux
 385  */
 386
 387 static int __init videodev_init(void)
 388 {
 389         int ret;
 390
 391         printk(KERN_INFO "Linux video capture interface: v1.00\n");
 392         if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
 393                 printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
 394                 return -EIO;
 395         }
 396
 397         ret = class_register(&video_class);
 398         if (ret < 0) {
 399                 unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 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         class_unregister(&video_class);
 410         unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 411 }
 412
 413 module_init(videodev_init)
 414 module_exit(videodev_exit)
 415
 416 EXPORT_SYMBOL(video_register_device);
 417 EXPORT_SYMBOL(video_unregister_device);
 418 EXPORT_SYMBOL(video_devdata);
 419 EXPORT_SYMBOL(video_usercopy);
 420 EXPORT_SYMBOL(video_exclusive_open);
 421 EXPORT_SYMBOL(video_exclusive_release);
 422 EXPORT_SYMBOL(video_device_alloc);
 423 EXPORT_SYMBOL(video_device_release);
 424
 425 MODULE_AUTHOR("Alan Cox");
 426 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers");
 427 MODULE_LICENSE("GPL");
 428
 429
 430 /*
 431  * Local variables:
 432  * c-basic-offset: 8
 433  * End:
 434  */