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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#include <linux/debugfs.h>
24
25struct media_device;
26
27/* debugfs top-level media directory */
28extern struct dentry *media_debugfs_root;
29
30/*
31 * Flag to mark the media_devnode struct as registered. Drivers must not touch
32 * this flag directly, it will be set and cleared by media_devnode_register and
33 * media_devnode_unregister.
34 */
35#define MEDIA_FLAG_REGISTERED 0
36
37/**
38 * struct media_file_operations - Media device file operations
39 *
40 * @owner: should be filled with %THIS_MODULE
41 * @read: pointer to the function that implements read() syscall
42 * @write: pointer to the function that implements write() syscall
43 * @poll: pointer to the function that implements poll() syscall
44 * @ioctl: pointer to the function that implements ioctl() syscall
45 * @compat_ioctl: pointer to the function that will handle 32 bits userspace
46 * calls to the ioctl() syscall on a Kernel compiled with 64 bits.
47 * @open: pointer to the function that implements open() syscall
48 * @release: pointer to the function that will release the resources allocated
49 * by the @open function.
50 */
51struct media_file_operations {
52 struct module *owner;
53 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
54 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
55 __poll_t (*poll) (struct file *, struct poll_table_struct *);
56 long (*ioctl) (struct file *, unsigned int, unsigned long);
57 long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
58 int (*open) (struct file *);
59 int (*release) (struct file *);
60};
61
62/**
63 * struct media_devnode - Media device node
64 * @media_dev: pointer to struct &media_device
65 * @fops: pointer to struct &media_file_operations with media device ops
66 * @dev: pointer to struct &device containing the media controller device
67 * @cdev: struct cdev pointer character device
68 * @parent: parent device
69 * @minor: device node minor number
70 * @flags: flags, combination of the ``MEDIA_FLAG_*`` constants
71 * @release: release callback called at the end of ``media_devnode_release()``
72 * routine at media-device.c.
73 *
74 * This structure represents a media-related device node.
75 *
76 * The @parent is a physical device. It must be set by core or device drivers
77 * before registering the node.
78 */
79struct media_devnode {
80 struct media_device *media_dev;
81
82 /* device ops */
83 const struct media_file_operations *fops;
84
85 /* sysfs */
86 struct device dev; /* media device */
87 struct cdev cdev; /* character device */
88 struct device *parent; /* device parent */
89
90 /* device info */
91 int minor;
92 unsigned long flags; /* Use bitops to access flags */
93
94 /* callbacks */
95 void (*release)(struct media_devnode *devnode);
96};
97
98/* dev to media_devnode */
99#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
100
101/**
102 * media_devnode_register - register a media device node
103 *
104 * @mdev: struct media_device we want to register a device node
105 * @devnode: media device node structure we want to register
106 * @owner: should be filled with %THIS_MODULE
107 *
108 * The registration code assigns minor numbers and registers the new device node
109 * with the kernel. An error is returned if no free minor number can be found,
110 * or if the registration of the device node fails.
111 *
112 * Zero is returned on success.
113 *
114 * Note that if the media_devnode_register call fails, the release() callback of
115 * the media_devnode structure is *not* called, so the caller is responsible for
116 * freeing any data.
117 */
118int __must_check media_devnode_register(struct media_device *mdev,
119 struct media_devnode *devnode,
120 struct module *owner);
121
122/**
123 * media_devnode_unregister_prepare - clear the media device node register bit
124 * @devnode: the device node to prepare for unregister
125 *
126 * This clears the passed device register bit. Future open calls will be met
127 * with errors. Should be called before media_devnode_unregister() to avoid
128 * races with unregister and device file open calls.
129 *
130 * This function can safely be called if the device node has never been
131 * registered or has already been unregistered.
132 */
133void media_devnode_unregister_prepare(struct media_devnode *devnode);
134
135/**
136 * media_devnode_unregister - unregister a media device node
137 * @devnode: the device node to unregister
138 *
139 * This unregisters the passed device. Future open calls will be met with
140 * errors.
141 *
142 * Should be called after media_devnode_unregister_prepare()
143 */
144void media_devnode_unregister(struct media_devnode *devnode);
145
146/**
147 * media_devnode_data - returns a pointer to the &media_devnode
148 *
149 * @filp: pointer to struct &file
150 */
151static inline struct media_devnode *media_devnode_data(struct file *filp)
152{
153 return filp->private_data;
154}
155
156/**
157 * media_devnode_is_registered - returns true if &media_devnode is registered;
158 * false otherwise.
159 *
160 * @devnode: pointer to struct &media_devnode.
161 *
162 * Note: If mdev is NULL, it also returns false.
163 */
164static inline int media_devnode_is_registered(struct media_devnode *devnode)
165{
166 if (!devnode)
167 return false;
168
169 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
170}
171
172#endif /* _MEDIA_DEVNODE_H */