1/* 2 * Media device node 3 * 4 * Copyright (C) 2010 Nokia Corporation 5 * 6 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com> 7 * Sakari Ailus <sakari.ailus@iki.fi> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * -- 19 * 20 * Common functions for media-related drivers to register and unregister media 21 * device nodes. 22 */ 23 24#ifndef _MEDIA_DEVNODE_H 25#define _MEDIA_DEVNODE_H 26 27#include <linux/poll.h> 28#include <linux/fs.h> 29#include <linux/device.h> 30#include <linux/cdev.h> 31 32struct media_device; 33 34/* 35 * Flag to mark the media_devnode struct as registered. Drivers must not touch 36 * this flag directly, it will be set and cleared by media_devnode_register and 37 * media_devnode_unregister. 38 */ 39#define MEDIA_FLAG_REGISTERED 0 40 41/** 42 * struct media_file_operations - Media device file operations 43 * 44 * @owner: should be filled with %THIS_MODULE 45 * @read: pointer to the function that implements read() syscall 46 * @write: pointer to the function that implements write() syscall 47 * @poll: pointer to the function that implements poll() syscall 48 * @ioctl: pointer to the function that implements ioctl() syscall 49 * @compat_ioctl: pointer to the function that will handle 32 bits userspace 50 * calls to the the ioctl() syscall on a Kernel compiled with 64 bits. 51 * @open: pointer to the function that implements open() syscall 52 * @release: pointer to the function that will release the resources allocated 53 * by the @open function. 54 */ 55struct media_file_operations { 56 struct module *owner; 57 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 58 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 59 __poll_t (*poll) (struct file *, struct poll_table_struct *); 60 long (*ioctl) (struct file *, unsigned int, unsigned long); 61 long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 62 int (*open) (struct file *); 63 int (*release) (struct file *); 64}; 65 66/** 67 * struct media_devnode - Media device node 68 * @media_dev: pointer to struct &media_device 69 * @fops: pointer to struct &media_file_operations with media device ops 70 * @dev: pointer to struct &device containing the media controller device 71 * @cdev: struct cdev pointer character device 72 * @parent: parent device 73 * @minor: device node minor number 74 * @flags: flags, combination of the ``MEDIA_FLAG_*`` constants 75 * @release: release callback called at the end of ``media_devnode_release()`` 76 * routine at media-device.c. 77 * 78 * This structure represents a media-related device node. 79 * 80 * The @parent is a physical device. It must be set by core or device drivers 81 * before registering the node. 82 */ 83struct media_devnode { 84 struct media_device *media_dev; 85 86 /* device ops */ 87 const struct media_file_operations *fops; 88 89 /* sysfs */ 90 struct device dev; /* media device */ 91 struct cdev cdev; /* character device */ 92 struct device *parent; /* device parent */ 93 94 /* device info */ 95 int minor; 96 unsigned long flags; /* Use bitops to access flags */ 97 98 /* callbacks */ 99 void (*release)(struct media_devnode *devnode); 100}; 101 102/* dev to media_devnode */ 103#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 104 105/** 106 * media_devnode_register - register a media device node 107 * 108 * @mdev: struct media_device we want to register a device node 109 * @devnode: media device node structure we want to register 110 * @owner: should be filled with %THIS_MODULE 111 * 112 * The registration code assigns minor numbers and registers the new device node 113 * with the kernel. An error is returned if no free minor number can be found, 114 * or if the registration of the device node fails. 115 * 116 * Zero is returned on success. 117 * 118 * Note that if the media_devnode_register call fails, the release() callback of 119 * the media_devnode structure is *not* called, so the caller is responsible for 120 * freeing any data. 121 */ 122int __must_check media_devnode_register(struct media_device *mdev, 123 struct media_devnode *devnode, 124 struct module *owner); 125 126/** 127 * media_devnode_unregister_prepare - clear the media device node register bit 128 * @devnode: the device node to prepare for unregister 129 * 130 * This clears the passed device register bit. Future open calls will be met 131 * with errors. Should be called before media_devnode_unregister() to avoid 132 * races with unregister and device file open calls. 133 * 134 * This function can safely be called if the device node has never been 135 * registered or has already been unregistered. 136 */ 137void media_devnode_unregister_prepare(struct media_devnode *devnode); 138 139/** 140 * media_devnode_unregister - unregister a media device node 141 * @devnode: the device node to unregister 142 * 143 * This unregisters the passed device. Future open calls will be met with 144 * errors. 145 * 146 * Should be called after media_devnode_unregister_prepare() 147 */ 148void media_devnode_unregister(struct media_devnode *devnode); 149 150/** 151 * media_devnode_data - returns a pointer to the &media_devnode 152 * 153 * @filp: pointer to struct &file 154 */ 155static inline struct media_devnode *media_devnode_data(struct file *filp) 156{ 157 return filp->private_data; 158} 159 160/** 161 * media_devnode_is_registered - returns true if &media_devnode is registered; 162 * false otherwise. 163 * 164 * @devnode: pointer to struct &media_devnode. 165 * 166 * Note: If mdev is NULL, it also returns false. 167 */ 168static inline int media_devnode_is_registered(struct media_devnode *devnode) 169{ 170 if (!devnode) 171 return false; 172 173 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); 174} 175 176#endif /* _MEDIA_DEVNODE_H */ 177