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 (v4l2_dev == NULL)
  30                 return -EINVAL;
  31
  32         INIT_LIST_HEAD(&v4l2_dev->subdevs);
  33         spin_lock_init(&v4l2_dev->lock);
  34         v4l2_dev->dev = dev;
  35         if (dev == NULL) {
  36                 /* If dev == NULL, then name must be filled in by the caller */
  37                 WARN_ON(!v4l2_dev->name[0]);
  38                 return 0;
  39         }
  40
  41         /* Set name to driver name + device name if it is empty. */
  42         if (!v4l2_dev->name[0])
  43                 snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
  44                         dev->driver->name, dev_name(dev));
  45         if (dev_get_drvdata(dev))
  46                 v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n");
  47         dev_set_drvdata(dev, v4l2_dev);
  48         return 0;
  49 }
  50 EXPORT_SYMBOL_GPL(v4l2_device_register);
  51
  52 void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
  53 {
  54         struct v4l2_subdev *sd, *next;
  55
  56         if (v4l2_dev == NULL)
  57                 return;
  58         if (v4l2_dev->dev)
  59                 dev_set_drvdata(v4l2_dev->dev, NULL);
  60         /* Unregister subdevs */
  61         list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list)
  62                 v4l2_device_unregister_subdev(sd);
  63
  64         v4l2_dev->dev = NULL;
  65 }
  66 EXPORT_SYMBOL_GPL(v4l2_device_unregister);
  67
  68 int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
  69                                                 struct v4l2_subdev *sd)
  70 {
  71         /* Check for valid input */
  72         if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
  73                 return -EINVAL;
  74         /* Warn if we apparently re-register a subdev */
  75         WARN_ON(sd->v4l2_dev != NULL);
  76         if (!try_module_get(sd->owner))
  77                 return -ENODEV;
  78         sd->v4l2_dev = v4l2_dev;
  79         spin_lock(&v4l2_dev->lock);
  80         list_add_tail(&sd->list, &v4l2_dev->subdevs);
  81         spin_unlock(&v4l2_dev->lock);
  82         return 0;
  83 }
  84 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
  85
  86 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
  87 {
  88         /* return if it isn't registered */
  89         if (sd == NULL || sd->v4l2_dev == NULL)
  90                 return;
  91         spin_lock(&sd->v4l2_dev->lock);
  92         list_del(&sd->list);
  93         spin_unlock(&sd->v4l2_dev->lock);
  94         sd->v4l2_dev = NULL;
  95         module_put(sd->owner);
  96 }
  97 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);