drivers/media/video/v4l2-device.c

   1 /*
   2     V4L2 device support.
   3
   4     Copyright (C) 2008  Hans Verkuil <hverkuil@xs4all.nl>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/types.h>
  22 #include <linux/ioctl.h>
  23 #include <linux/i2c.h>
  24 #include <linux/videodev2.h>
  25 #include <media/v4l2-device.h>
  26
  27 int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
  28 {
  29         if (dev == NULL || v4l2_dev == NULL)
  30                 return -EINVAL;
  31         /* Warn if we apparently re-register a device */
  32         WARN_ON(dev_get_drvdata(dev) != NULL);
  33         INIT_LIST_HEAD(&v4l2_dev->subdevs);
  34         spin_lock_init(&v4l2_dev->lock);
  35         v4l2_dev->dev = dev;
  36         snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
  37                         dev->driver->name, dev_name(dev));
  38         dev_set_drvdata(dev, v4l2_dev);
  39         return 0;
  40 }
  41 EXPORT_SYMBOL_GPL(v4l2_device_register);
  42
  43 void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
  44 {
  45         struct v4l2_subdev *sd, *next;
  46
  47         if (v4l2_dev == NULL || v4l2_dev->dev == NULL)
  48                 return;
  49         dev_set_drvdata(v4l2_dev->dev, NULL);
  50         /* unregister subdevs */
  51         list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
  52                 v4l2_device_unregister_subdev(sd);
  53
  54         v4l2_dev->dev = NULL;
  55 }
  56 EXPORT_SYMBOL_GPL(v4l2_device_unregister);
  57
  58 int v4l2_device_register_subdev(struct v4l2_device *dev, struct v4l2_subdev *sd)
  59 {
  60         /* Check for valid input */
  61         if (dev == NULL || sd == NULL || !sd->name[0])
  62                 return -EINVAL;
  63         /* Warn if we apparently re-register a subdev */
  64         WARN_ON(sd->dev != NULL);
  65         if (!try_module_get(sd->owner))
  66                 return -ENODEV;
  67         sd->dev = dev;
  68         spin_lock(&dev->lock);
  69         list_add_tail(&sd->list, &dev->subdevs);
  70         spin_unlock(&dev->lock);
  71         return 0;
  72 }
  73 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
  74
  75 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
  76 {
  77         /* return if it isn't registered */
  78         if (sd == NULL || sd->dev == NULL)
  79                 return;
  80         spin_lock(&sd->dev->lock);
  81         list_del(&sd->list);
  82         spin_unlock(&sd->dev->lock);
  83         sd->dev = NULL;
  84         module_put(sd->owner);
  85 }
  86 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);