1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Media device node
  4 *
  5 * Copyright (C) 2010 Nokia Corporation
  6 *
  7 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  8 *	     Sakari Ailus <sakari.ailus@iki.fi>
  9 *
 10 * --
 11 *
 12 * Common functions for media-related drivers to register and unregister media
 13 * device nodes.
 14 */
 15
 16#ifndef _MEDIA_DEVNODE_H
 17#define _MEDIA_DEVNODE_H
 18
 19#include <linux/poll.h>
 20#include <linux/fs.h>
 21#include <linux/device.h>
 22#include <linux/cdev.h>
 23
 24struct media_device;
 25
 26/*
 27 * Flag to mark the media_devnode struct as registered. Drivers must not touch
 28 * this flag directly, it will be set and cleared by media_devnode_register and
 29 * media_devnode_unregister.
 30 */
 31#define MEDIA_FLAG_REGISTERED	0
 32
 33/**
 34 * struct media_file_operations - Media device file operations
 35 *
 36 * @owner: should be filled with %THIS_MODULE
 37 * @read: pointer to the function that implements read() syscall
 38 * @write: pointer to the function that implements write() syscall
 39 * @poll: pointer to the function that implements poll() syscall
 40 * @ioctl: pointer to the function that implements ioctl() syscall
 41 * @compat_ioctl: pointer to the function that will handle 32 bits userspace
 42 *	calls to the ioctl() syscall on a Kernel compiled with 64 bits.
 43 * @open: pointer to the function that implements open() syscall
 44 * @release: pointer to the function that will release the resources allocated
 45 *	by the @open function.
 46 */
 47struct media_file_operations {
 48	struct module *owner;
 49	ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
 50	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
 51	__poll_t (*poll) (struct file *, struct poll_table_struct *);
 52	long (*ioctl) (struct file *, unsigned int, unsigned long);
 53	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
 54	int (*open) (struct file *);
 55	int (*release) (struct file *);
 56};
 57
 58/**
 59 * struct media_devnode - Media device node
 60 * @media_dev:	pointer to struct &media_device
 61 * @fops:	pointer to struct &media_file_operations with media device ops
 62 * @dev:	pointer to struct &device containing the media controller device
 63 * @cdev:	struct cdev pointer character device
 64 * @parent:	parent device
 65 * @minor:	device node minor number
 66 * @flags:	flags, combination of the ``MEDIA_FLAG_*`` constants
 67 * @release:	release callback called at the end of ``media_devnode_release()``
 68 *		routine at media-device.c.
 69 *
 70 * This structure represents a media-related device node.
 71 *
 72 * The @parent is a physical device. It must be set by core or device drivers
 73 * before registering the node.
 74 */
 75struct media_devnode {
 76	struct media_device *media_dev;
 77
 78	/* device ops */
 79	const struct media_file_operations *fops;
 80
 81	/* sysfs */
 82	struct device dev;		/* media device */
 83	struct cdev cdev;		/* character device */
 84	struct device *parent;		/* device parent */
 85
 86	/* device info */
 87	int minor;
 88	unsigned long flags;		/* Use bitops to access flags */
 89
 90	/* callbacks */
 91	void (*release)(struct media_devnode *devnode);
 92};
 93
 94/* dev to media_devnode */
 95#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
 96
 97/**
 98 * media_devnode_register - register a media device node
 99 *
100 * @mdev: struct media_device we want to register a device node
101 * @devnode: media device node structure we want to register
102 * @owner: should be filled with %THIS_MODULE
103 *
104 * The registration code assigns minor numbers and registers the new device node
105 * with the kernel. An error is returned if no free minor number can be found,
106 * or if the registration of the device node fails.
107 *
108 * Zero is returned on success.
109 *
110 * Note that if the media_devnode_register call fails, the release() callback of
111 * the media_devnode structure is *not* called, so the caller is responsible for
112 * freeing any data.
113 */
114int __must_check media_devnode_register(struct media_device *mdev,
115					struct media_devnode *devnode,
116					struct module *owner);
117
118/**
119 * media_devnode_unregister_prepare - clear the media device node register bit
120 * @devnode: the device node to prepare for unregister
121 *
122 * This clears the passed device register bit. Future open calls will be met
123 * with errors. Should be called before media_devnode_unregister() to avoid
124 * races with unregister and device file open calls.
125 *
126 * This function can safely be called if the device node has never been
127 * registered or has already been unregistered.
128 */
129void media_devnode_unregister_prepare(struct media_devnode *devnode);
130
131/**
132 * media_devnode_unregister - unregister a media device node
133 * @devnode: the device node to unregister
134 *
135 * This unregisters the passed device. Future open calls will be met with
136 * errors.
137 *
138 * Should be called after media_devnode_unregister_prepare()
139 */
140void media_devnode_unregister(struct media_devnode *devnode);
141
142/**
143 * media_devnode_data - returns a pointer to the &media_devnode
144 *
145 * @filp: pointer to struct &file
146 */
147static inline struct media_devnode *media_devnode_data(struct file *filp)
148{
149	return filp->private_data;
150}
151
152/**
153 * media_devnode_is_registered - returns true if &media_devnode is registered;
154 *	false otherwise.
155 *
156 * @devnode: pointer to struct &media_devnode.
157 *
158 * Note: If mdev is NULL, it also returns false.
159 */
160static inline int media_devnode_is_registered(struct media_devnode *devnode)
161{
162	if (!devnode)
163		return false;
164
165	return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
166}
167
168#endif /* _MEDIA_DEVNODE_H */