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 = kmalloc(sizeof(*vfd),GFP_KERNEL);
  56         if (NULL == vfd)
  57                 return NULL;
  58         memset(vfd,0,sizeof(*vfd));
  59         return vfd;
  60 }
  61
  62 void video_device_release(struct video_device *vfd)
  63 {
  64         kfree(vfd);
  65 }
  66
  67 static void video_release(struct class_device *cd)
  68 {
  69         struct video_device *vfd = container_of(cd, struct video_device, class_dev);
  70
  71 #if 1 /* needed until all drivers are fixed */
  72         if (!vfd->release)
  73                 return;
  74 #endif
  75         vfd->release(vfd);
  76 }
  77
  78 static struct class video_class = {
  79         .name    = VIDEO_NAME,
  80         .release = video_release,
  81 };
  82
  83 /*
  84  *      Active devices
  85  */
  86
  87 static struct video_device *video_device[VIDEO_NUM_DEVICES];
  88 static DECLARE_MUTEX(videodev_lock);
  89
  90 struct video_device* video_devdata(struct file *file)
  91 {
  92         return video_device[iminor(file->f_dentry->d_inode)];
  93 }
  94
  95 /*
  96  *      Open a video device.
  97  */
  98 static int video_open(struct inode *inode, struct file *file)
  99 {
 100         unsigned int minor = iminor(inode);
 101         int err = 0;
 102         struct video_device *vfl;
 103         struct file_operations *old_fops;
 104
 105         if(minor>=VIDEO_NUM_DEVICES)
 106                 return -ENODEV;
 107         down(&videodev_lock);
 108         vfl=video_device[minor];
 109         if(vfl==NULL) {
 110                 up(&videodev_lock);
 111                 request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
 112                 down(&videodev_lock);
 113                 vfl=video_device[minor];
 114                 if (vfl==NULL) {
 115                         up(&videodev_lock);
 116                         return -ENODEV;
 117                 }
 118         }
 119         old_fops = file->f_op;
 120         file->f_op = fops_get(vfl->fops);
 121         if(file->f_op->open)
 122                 err = file->f_op->open(inode,file);
 123         if (err) {
 124                 fops_put(file->f_op);
 125                 file->f_op = fops_get(old_fops);
 126         }
 127         fops_put(old_fops);
 128         up(&videodev_lock);
 129         return err;
 130 }
 131
 132 /*
 133  * helper function -- handles userspace copying for ioctl arguments
 134  */
 135
 136 static unsigned int
 137 video_fix_command(unsigned int cmd)
 138 {
 139         switch (cmd) {
 140         case VIDIOC_OVERLAY_OLD:
 141                 cmd = VIDIOC_OVERLAY;
 142                 break;
 143         case VIDIOC_S_PARM_OLD:
 144                 cmd = VIDIOC_S_PARM;
 145                 break;
 146         case VIDIOC_S_CTRL_OLD:
 147                 cmd = VIDIOC_S_CTRL;
 148                 break;
 149         case VIDIOC_G_AUDIO_OLD:
 150                 cmd = VIDIOC_G_AUDIO;
 151                 break;
 152         case VIDIOC_G_AUDOUT_OLD:
 153                 cmd = VIDIOC_G_AUDOUT;
 154                 break;
 155         case VIDIOC_CROPCAP_OLD:
 156                 cmd = VIDIOC_CROPCAP;
 157                 break;
 158         }
 159         return cmd;
 160 }
 161
 162 int
 163 video_usercopy(struct inode *inode, struct file *file,
 164                unsigned int cmd, unsigned long arg,
 165                int (*func)(struct inode *inode, struct file *file,
 166                            unsigned int cmd, void *arg))
 167 {
 168         char    sbuf[128];
 169         void    *mbuf = NULL;
 170         void    *parg = NULL;
 171         int     err  = -EINVAL;
 172
 173         cmd = video_fix_command(cmd);
 174
 175         /*  Copy arguments into temp kernel buffer  */
 176         switch (_IOC_DIR(cmd)) {
 177         case _IOC_NONE:
 178                 parg = NULL;
 179                 break;
 180         case _IOC_READ:
 181         case _IOC_WRITE:
 182         case (_IOC_WRITE | _IOC_READ):
 183                 if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
 184                         parg = sbuf;
 185                 } else {
 186                         /* too big to allocate from stack */
 187                         mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
 188                         if (NULL == mbuf)
 189                                 return -ENOMEM;
 190                         parg = mbuf;
 191                 }
 192
 193                 err = -EFAULT;
 194                 if (_IOC_DIR(cmd) & _IOC_WRITE)
 195                         if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
 196                                 goto out;
 197                 break;
 198         }
 199
 200         /* call driver */
 201         err = func(inode, file, cmd, parg);
 202         if (err == -ENOIOCTLCMD)
 203                 err = -EINVAL;
 204         if (err < 0)
 205                 goto out;
 206
 207         /*  Copy results into user buffer  */
 208         switch (_IOC_DIR(cmd))
 209         {
 210         case _IOC_READ:
 211         case (_IOC_WRITE | _IOC_READ):
 212                 if (copy_to_user((void __user *)arg, parg, _IOC_SIZE(cmd)))
 213                         err = -EFAULT;
 214                 break;
 215         }
 216
 217 out:
 218         kfree(mbuf);
 219         return err;
 220 }
 221
 222 /*
 223  * open/release helper functions -- handle exclusive opens
 224  */
 225 int video_exclusive_open(struct inode *inode, struct file *file)
 226 {
 227         struct  video_device *vfl = video_devdata(file);
 228         int retval = 0;
 229
 230         down(&vfl->lock);
 231         if (vfl->users) {
 232                 retval = -EBUSY;
 233         } else {
 234                 vfl->users++;
 235         }
 236         up(&vfl->lock);
 237         return retval;
 238 }
 239
 240 int video_exclusive_release(struct inode *inode, struct file *file)
 241 {
 242         struct  video_device *vfl = video_devdata(file);
 243
 244         vfl->users--;
 245         return 0;
 246 }
 247
 248 static struct file_operations video_fops;
 249
 250 /**
 251  *      video_register_device - register video4linux devices
 252  *      @vfd:  video device structure we want to register
 253  *      @type: type of device to register
 254  *      @nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 255  *             -1 == first free)
 256  *
 257  *      The registration code assigns minor numbers based on the type
 258  *      requested. -ENFILE is returned in all the device slots for this
 259  *      category are full. If not then the minor field is set and the
 260  *      driver initialize function is called (if non %NULL).
 261  *
 262  *      Zero is returned on success.
 263  *
 264  *      Valid types are
 265  *
 266  *      %VFL_TYPE_GRABBER - A frame grabber
 267  *
 268  *      %VFL_TYPE_VTX - A teletext device
 269  *
 270  *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 271  *
 272  *      %VFL_TYPE_RADIO - A radio card
 273  */
 274
 275 int video_register_device(struct video_device *vfd, int type, int nr)
 276 {
 277         int i=0;
 278         int base;
 279         int end;
 280         char *name_base;
 281
 282         switch(type)
 283         {
 284                 case VFL_TYPE_GRABBER:
 285                         base=0;
 286                         end=64;
 287                         name_base = "video";
 288                         break;
 289                 case VFL_TYPE_VTX:
 290                         base=192;
 291                         end=224;
 292                         name_base = "vtx";
 293                         break;
 294                 case VFL_TYPE_VBI:
 295                         base=224;
 296                         end=256;
 297                         name_base = "vbi";
 298                         break;
 299                 case VFL_TYPE_RADIO:
 300                         base=64;
 301                         end=128;
 302                         name_base = "radio";
 303                         break;
 304                 default:
 305                         return -1;
 306         }
 307
 308         /* pick a minor number */
 309         down(&videodev_lock);
 310         if (nr >= 0  &&  nr < end-base) {
 311                 /* use the one the driver asked for */
 312                 i = base+nr;
 313                 if (NULL != video_device[i]) {
 314                         up(&videodev_lock);
 315                         return -ENFILE;
 316                 }
 317         } else {
 318                 /* use first free */
 319                 for(i=base;i<end;i++)
 320                         if (NULL == video_device[i])
 321                                 break;
 322                 if (i == end) {
 323                         up(&videodev_lock);
 324                         return -ENFILE;
 325                 }
 326         }
 327         video_device[i]=vfd;
 328         vfd->minor=i;
 329         up(&videodev_lock);
 330
 331         sprintf(vfd->devfs_name, "v4l/%s%d", name_base, i - base);
 332         devfs_mk_cdev(MKDEV(VIDEO_MAJOR, vfd->minor),
 333                         S_IFCHR | S_IRUSR | S_IWUSR, vfd->devfs_name);
 334         init_MUTEX(&vfd->lock);
 335
 336         /* sysfs class */
 337         memset(&vfd->class_dev, 0x00, sizeof(vfd->class_dev));
 338         if (vfd->dev)
 339                 vfd->class_dev.dev = vfd->dev;
 340         vfd->class_dev.class       = &video_class;
 341         vfd->class_dev.devt       = MKDEV(VIDEO_MAJOR, vfd->minor);
 342         strlcpy(vfd->class_dev.class_id, vfd->devfs_name + 4, BUS_ID_SIZE);
 343         class_device_register(&vfd->class_dev);
 344         class_device_create_file(&vfd->class_dev,
 345                                  &class_device_attr_name);
 346
 347 #if 1 /* needed until all drivers are fixed */
 348         if (!vfd->release)
 349                 printk(KERN_WARNING "videodev: \"%s\" has no release callback. "
 350                        "Please fix your driver for proper sysfs support, see "
 351                        "http://lwn.net/Articles/36850/\n", vfd->name);
 352 #endif
 353         return 0;
 354 }
 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         down(&videodev_lock);
 367         if(video_device[vfd->minor]!=vfd)
 368                 panic("videodev: bad unregister");
 369
 370         devfs_remove(vfd->devfs_name);
 371         video_device[vfd->minor]=NULL;
 372         class_device_unregister(&vfd->class_dev);
 373         up(&videodev_lock);
 374 }
 375
 376
 377 static struct file_operations video_fops=
 378 {
 379         .owner          = THIS_MODULE,
 380         .llseek         = no_llseek,
 381         .open           = video_open,
 382 };
 383
 384 /*
 385  *      Initialise video for linux
 386  */
 387
 388 static int __init videodev_init(void)
 389 {
 390         int ret;
 391
 392         printk(KERN_INFO "Linux video capture interface: v1.00\n");
 393         if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
 394                 printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
 395                 return -EIO;
 396         }
 397
 398         ret = class_register(&video_class);
 399         if (ret < 0) {
 400                 unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 401                 printk(KERN_WARNING "video_dev: class_register failed\n");
 402                 return -EIO;
 403         }
 404
 405         return 0;
 406 }
 407
 408 static void __exit videodev_exit(void)
 409 {
 410         class_unregister(&video_class);
 411         unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
 412 }
 413
 414 module_init(videodev_init)
 415 module_exit(videodev_exit)
 416
 417 EXPORT_SYMBOL(video_register_device);
 418 EXPORT_SYMBOL(video_unregister_device);
 419 EXPORT_SYMBOL(video_devdata);
 420 EXPORT_SYMBOL(video_usercopy);
 421 EXPORT_SYMBOL(video_exclusive_open);
 422 EXPORT_SYMBOL(video_exclusive_release);
 423 EXPORT_SYMBOL(video_device_alloc);
 424 EXPORT_SYMBOL(video_device_release);
 425
 426 MODULE_AUTHOR("Alan Cox");
 427 MODULE_DESCRIPTION("Device registrar for Video4Linux drivers");
 428 MODULE_LICENSE("GPL");
 429
 430
 431 /*
 432  * Local variables:
 433  * c-basic-offset: 8
 434  * End:
 435  */