/* SPDX-License-Identifier: GPL-2.0-only */

  /*
   * Media device node
   *
   * Copyright (C) 2010 Nokia Corporation
   *
   * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
   *	     Sakari Ailus <sakari.ailus@iki.fi>
   *

   * --
   *
   * Common functions for media-related drivers to register and unregister media
   * device nodes.
   */
  
  #ifndef _MEDIA_DEVNODE_H
  #define _MEDIA_DEVNODE_H
  
  #include <linux/poll.h>
  #include <linux/fs.h>
  #include <linux/device.h>
  #include <linux/cdev.h>

  struct media_device;

  /*
   * Flag to mark the media_devnode struct as registered. Drivers must not touch
   * this flag directly, it will be set and cleared by media_devnode_register and
   * media_devnode_unregister.
   */
  #define MEDIA_FLAG_REGISTERED	0

  /**
   * struct media_file_operations - Media device file operations
   *
   * @owner: should be filled with %THIS_MODULE
   * @read: pointer to the function that implements read() syscall
   * @write: pointer to the function that implements write() syscall
   * @poll: pointer to the function that implements poll() syscall
   * @ioctl: pointer to the function that implements ioctl() syscall
   * @compat_ioctl: pointer to the function that will handle 32 bits userspace

   *	calls to the ioctl() syscall on a Kernel compiled with 64 bits.

   * @open: pointer to the function that implements open() syscall
   * @release: pointer to the function that will release the resources allocated
   *	by the @open function.
   */

  struct media_file_operations {
  	struct module *owner;
  	ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
  	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);

  	__poll_t (*poll) (struct file *, struct poll_table_struct *);

  	long (*ioctl) (struct file *, unsigned int, unsigned long);

  	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);

  	int (*open) (struct file *);
  	int (*release) (struct file *);
  };
  
  /**
   * struct media_devnode - Media device node

   * @media_dev:	pointer to struct &media_device

   * @fops:	pointer to struct &media_file_operations with media device ops

   * @dev:	pointer to struct &device containing the media controller device

   * @cdev:	struct cdev pointer character device

   * @parent:	parent device
   * @minor:	device node minor number

   * @flags:	flags, combination of the ``MEDIA_FLAG_*`` constants

   * @release:	release callback called at the end of ``media_devnode_release()``
   *		routine at media-device.c.

   *
   * This structure represents a media-related device node.
   *
   * The @parent is a physical device. It must be set by core or device drivers
   * before registering the node.
   */
  struct media_devnode {

  	struct media_device *media_dev;

  	/* device ops */
  	const struct media_file_operations *fops;
  
  	/* sysfs */
  	struct device dev;		/* media device */
  	struct cdev cdev;		/* character device */
  	struct device *parent;		/* device parent */
  
  	/* device info */
  	int minor;
  	unsigned long flags;		/* Use bitops to access flags */
  
  	/* callbacks */

  	void (*release)(struct media_devnode *devnode);

  };
  
  /* dev to media_devnode */
  #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)

  /**
   * media_devnode_register - register a media device node
   *

   * @mdev: struct media_device we want to register a device node

   * @devnode: media device node structure we want to register

   * @owner: should be filled with %THIS_MODULE
   *
   * The registration code assigns minor numbers and registers the new device node
   * with the kernel. An error is returned if no free minor number can be found,
   * or if the registration of the device node fails.
   *
   * Zero is returned on success.
   *
   * Note that if the media_devnode_register call fails, the release() callback of
   * the media_devnode structure is *not* called, so the caller is responsible for
   * freeing any data.
   */

  int __must_check media_devnode_register(struct media_device *mdev,
  					struct media_devnode *devnode,

  					struct module *owner);

  
  /**

   * media_devnode_unregister_prepare - clear the media device node register bit
   * @devnode: the device node to prepare for unregister
   *
   * This clears the passed device register bit. Future open calls will be met
   * with errors. Should be called before media_devnode_unregister() to avoid
   * races with unregister and device file open calls.
   *
   * This function can safely be called if the device node has never been
   * registered or has already been unregistered.
   */
  void media_devnode_unregister_prepare(struct media_devnode *devnode);
  
  /**

   * media_devnode_unregister - unregister a media device node

   * @devnode: the device node to unregister

   *
   * This unregisters the passed device. Future open calls will be met with
   * errors.
   *

   * Should be called after media_devnode_unregister_prepare()

   */

  void media_devnode_unregister(struct media_devnode *devnode);

  /**
   * media_devnode_data - returns a pointer to the &media_devnode
   *
   * @filp: pointer to struct &file
   */

  static inline struct media_devnode *media_devnode_data(struct file *filp)
  {
  	return filp->private_data;
  }

  /**
   * media_devnode_is_registered - returns true if &media_devnode is registered;
   *	false otherwise.
   *

   * @devnode: pointer to struct &media_devnode.

   *
   * Note: If mdev is NULL, it also returns false.

   */

  static inline int media_devnode_is_registered(struct media_devnode *devnode)

  {

  	if (!devnode)
  		return false;

  	return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);

  }
  
  #endif /* _MEDIA_DEVNODE_H */