Quelle  v4l2-device.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
    V4L2 device support.

    Copyright (C) 2008  Hans Verkuil <hverkuil@xs4all.nl>

 */

#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ctrls.h>

int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
{
 if (v4l2_dev == NULL)
  return -EINVAL;

 INIT_LIST_HEAD(&v4l2_dev->subdevs);
 spin_lock_init(&v4l2_dev->lock);
 v4l2_prio_init(&v4l2_dev->prio);
 kref_init(&v4l2_dev->ref);
 get_device(dev);
 v4l2_dev->dev = dev;
 if (dev == NULL) {
  /* If dev == NULL, then name must be filled in by the caller */
  if (WARN_ON(!v4l2_dev->name[0]))
   return -EINVAL;
  return 0;
 }

 /* Set name to driver name + device name if it is empty. */
 if (!v4l2_dev->name[0])
  snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
   dev->driver->name, dev_name(dev));
 if (!dev_get_drvdata(dev))
  dev_set_drvdata(dev, v4l2_dev);
 return 0;
}
EXPORT_SYMBOL_GPL(v4l2_device_register);

static void v4l2_device_release(struct kref *ref)
{
 struct v4l2_device *v4l2_dev =
  container_of(ref, struct v4l2_device, ref);

 if (v4l2_dev->release)
  v4l2_dev->release(v4l2_dev);
}

int v4l2_device_put(struct v4l2_device *v4l2_dev)
{
 return kref_put(&v4l2_dev->ref, v4l2_device_release);
}
EXPORT_SYMBOL_GPL(v4l2_device_put);

int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
      atomic_t *instance)
{
 int num = atomic_inc_return(instance) - 1;
 int len = strlen(basename);

 if (basename[len - 1] >= '0' && basename[len - 1] <= '9')
  snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
    "%s-%d", basename, num);
 else
  snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
    "%s%d", basename, num);
 return num;
}
EXPORT_SYMBOL_GPL(v4l2_device_set_name);

void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
{
 if (v4l2_dev->dev == NULL)
  return;

 if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev)
  dev_set_drvdata(v4l2_dev->dev, NULL);
 put_device(v4l2_dev->dev);
 v4l2_dev->dev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_device_disconnect);

void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
{
 struct v4l2_subdev *sd, *next;

 /* Just return if v4l2_dev is NULL or if it was already
 * unregistered before. */
 if (v4l2_dev == NULL || !v4l2_dev->name[0])
  return;
 v4l2_device_disconnect(v4l2_dev);

 /* Unregister subdevs */
 list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
  v4l2_device_unregister_subdev(sd);
  if (sd->flags & V4L2_SUBDEV_FL_IS_I2C)
   v4l2_i2c_subdev_unregister(sd);
  else if (sd->flags & V4L2_SUBDEV_FL_IS_SPI)
   v4l2_spi_subdev_unregister(sd);
 }
 /* Mark as unregistered, thus preventing duplicate unregistrations */
 v4l2_dev->name[0] = '\0';
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister);

int __v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
      struct v4l2_subdev *sd, struct module *module)
{
 int err;

 /* Check for valid input */
 if (!v4l2_dev || !sd || sd->v4l2_dev || !sd->name[0])
  return -EINVAL;

 /*
  * The reason to acquire the module here is to avoid unloading
  * a module of sub-device which is registered to a media
  * device. To make it possible to unload modules for media
  * devices that also register sub-devices, do not
  * try_module_get() such sub-device owners.
 */
 sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
  module == v4l2_dev->dev->driver->owner;

 if (!sd->owner_v4l2_dev && !try_module_get(module))
  return -ENODEV;

 sd->v4l2_dev = v4l2_dev;
 /* This just returns 0 if either of the two args is NULL */
 err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler,
        NULL, true);
 if (err)
  goto error_module;

#if defined(CONFIG_MEDIA_CONTROLLER)
 /* Register the entity. */
 if (v4l2_dev->mdev) {
  err = media_device_register_entity(v4l2_dev->mdev, &sd->entity);
  if (err < 0)
   goto error_module;
 }
#endif

 if (sd->internal_ops && sd->internal_ops->registered) {
  err = sd->internal_ops->registered(sd);
  if (err)
   goto error_unregister;
 }

 sd->owner = module;

 spin_lock(&v4l2_dev->lock);
 list_add_tail(&sd->list, &v4l2_dev->subdevs);
 spin_unlock(&v4l2_dev->lock);

 return 0;

error_unregister:
#if defined(CONFIG_MEDIA_CONTROLLER)
 media_device_unregister_entity(&sd->entity);
#endif
error_module:
 if (!sd->owner_v4l2_dev)
  module_put(sd->owner);
 sd->v4l2_dev = NULL;
 return err;
}
EXPORT_SYMBOL_GPL(__v4l2_device_register_subdev);

static void v4l2_subdev_release(struct v4l2_subdev *sd)
{
 struct module *owner = !sd->owner_v4l2_dev ? sd->owner : NULL;

 if (sd->internal_ops && sd->internal_ops->release)
  sd->internal_ops->release(sd);
 sd->devnode = NULL;
 module_put(owner);
}

static void v4l2_device_release_subdev_node(struct video_device *vdev)
{
 v4l2_subdev_release(video_get_drvdata(vdev));
 kfree(vdev);
}

int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
     bool read_only)
{
 struct video_device *vdev;
 struct v4l2_subdev *sd;
 int err;

 /* Register a device node for every subdev marked with the
  * V4L2_SUBDEV_FL_HAS_DEVNODE flag.
 */
 list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
  if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
   continue;

  if (sd->devnode)
   continue;

  vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
  if (!vdev) {
   err = -ENOMEM;
   goto clean_up;
  }

  video_set_drvdata(vdev, sd);
  strscpy(vdev->name, sd->name, sizeof(vdev->name));
  vdev->dev_parent = sd->dev;
  vdev->v4l2_dev = v4l2_dev;
  vdev->fops = &v4l2_subdev_fops;
  vdev->release = v4l2_device_release_subdev_node;
  vdev->ctrl_handler = sd->ctrl_handler;
  if (read_only)
   set_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags);
  sd->devnode = vdev;
  err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
           sd->owner);
  if (err < 0) {
   sd->devnode = NULL;
   kfree(vdev);
   goto clean_up;
  }
#if defined(CONFIG_MEDIA_CONTROLLER)
  sd->entity.info.dev.major = VIDEO_MAJOR;
  sd->entity.info.dev.minor = vdev->minor;

  /* Interface is created by __video_register_device() */
  if (vdev->v4l2_dev->mdev) {
   struct media_link *link;

   link = media_create_intf_link(&sd->entity,
            &vdev->intf_devnode->intf,
            MEDIA_LNK_FL_ENABLED |
            MEDIA_LNK_FL_IMMUTABLE);
   if (!link) {
    err = -ENOMEM;
    goto clean_up;
   }
  }
#endif
 }
 return 0;

clean_up:
 list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
  if (!sd->devnode)
   break;
  video_unregister_device(sd->devnode);
 }

 return err;
}
EXPORT_SYMBOL_GPL(__v4l2_device_register_subdev_nodes);

void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
{
 struct v4l2_device *v4l2_dev;

 /* return if it isn't registered */
 if (sd == NULL || sd->v4l2_dev == NULL)
  return;

 v4l2_dev = sd->v4l2_dev;

 spin_lock(&v4l2_dev->lock);
 list_del(&sd->list);
 spin_unlock(&v4l2_dev->lock);

 if (sd->internal_ops && sd->internal_ops->unregistered)
  sd->internal_ops->unregistered(sd);
 sd->v4l2_dev = NULL;

#if defined(CONFIG_MEDIA_CONTROLLER)
 if (v4l2_dev->mdev) {
  /*
   * No need to explicitly remove links, as both pads and
   * links are removed by the function below, in the right order
 */
  media_device_unregister_entity(&sd->entity);
 }
#endif
 if (sd->devnode)
  video_unregister_device(sd->devnode);
 else
  v4l2_subdev_release(sd);
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);