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 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 21 * 22 * -- 23 * 24 * Common functions for media-related drivers to register and unregister media 25 * device nodes. 26 */ 27 28#ifndef _MEDIA_DEVNODE_H 29#define _MEDIA_DEVNODE_H 30 31#include <linux/poll.h> 32#include <linux/fs.h> 33#include <linux/device.h> 34#include <linux/cdev.h> 35 36struct media_device; 37 38/* 39 * Flag to mark the media_devnode struct as registered. Drivers must not touch 40 * this flag directly, it will be set and cleared by media_devnode_register and 41 * media_devnode_unregister. 42 */ 43#define MEDIA_FLAG_REGISTERED 0 44 45/** 46 * struct media_file_operations - Media device file operations 47 * 48 * @owner: should be filled with %THIS_MODULE 49 * @read: pointer to the function that implements read() syscall 50 * @write: pointer to the function that implements write() syscall 51 * @poll: pointer to the function that implements poll() syscall 52 * @ioctl: pointer to the function that implements ioctl() syscall 53 * @compat_ioctl: pointer to the function that will handle 32 bits userspace 54 * calls to the the ioctl() syscall on a Kernel compiled with 64 bits. 55 * @open: pointer to the function that implements open() syscall 56 * @release: pointer to the function that will release the resources allocated 57 * by the @open function. 58 */ 59struct media_file_operations { 60 struct module *owner; 61 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 62 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 63 unsigned int (*poll) (struct file *, struct poll_table_struct *); 64 long (*ioctl) (struct file *, unsigned int, unsigned long); 65 long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 66 int (*open) (struct file *); 67 int (*release) (struct file *); 68}; 69 70/** 71 * struct media_devnode - Media device node 72 * @media_dev: pointer to struct &media_device 73 * @fops: pointer to struct &media_file_operations with media device ops 74 * @dev: pointer to struct &device containing the media controller device 75 * @cdev: struct cdev pointer character device 76 * @parent: parent device 77 * @minor: device node minor number 78 * @flags: flags, combination of the MEDIA_FLAG_* constants 79 * @release: release callback called at the end of media_devnode_release() 80 * 81 * This structure represents a media-related device node. 82 * 83 * The @parent is a physical device. It must be set by core or device drivers 84 * before registering the node. 85 */ 86struct media_devnode { 87 struct media_device *media_dev; 88 89 /* device ops */ 90 const struct media_file_operations *fops; 91 92 /* sysfs */ 93 struct device dev; /* media device */ 94 struct cdev cdev; /* character device */ 95 struct device *parent; /* device parent */ 96 97 /* device info */ 98 int minor; 99 unsigned long flags; /* Use bitops to access flags */ 100 101 /* callbacks */ 102 void (*release)(struct media_devnode *devnode); 103}; 104 105/* dev to media_devnode */ 106#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 107 108/** 109 * media_devnode_register - register a media device node 110 * 111 * @mdev: struct media_device we want to register a device node 112 * @devnode: media device node structure we want to register 113 * @owner: should be filled with %THIS_MODULE 114 * 115 * The registration code assigns minor numbers and registers the new device node 116 * with the kernel. An error is returned if no free minor number can be found, 117 * or if the registration of the device node fails. 118 * 119 * Zero is returned on success. 120 * 121 * Note that if the media_devnode_register call fails, the release() callback of 122 * the media_devnode structure is *not* called, so the caller is responsible for 123 * freeing any data. 124 */ 125int __must_check media_devnode_register(struct media_device *mdev, 126 struct media_devnode *devnode, 127 struct module *owner); 128 129/** 130 * media_devnode_unregister_prepare - clear the media device node register bit 131 * @devnode: the device node to prepare for unregister 132 * 133 * This clears the passed device register bit. Future open calls will be met 134 * with errors. Should be called before media_devnode_unregister() to avoid 135 * races with unregister and device file open calls. 136 * 137 * This function can safely be called if the device node has never been 138 * registered or has already been unregistered. 139 */ 140void media_devnode_unregister_prepare(struct media_devnode *devnode); 141 142/** 143 * media_devnode_unregister - unregister a media device node 144 * @devnode: the device node to unregister 145 * 146 * This unregisters the passed device. Future open calls will be met with 147 * errors. 148 * 149 * Should be called after media_devnode_unregister_prepare() 150 */ 151void media_devnode_unregister(struct media_devnode *devnode); 152 153/** 154 * media_devnode_data - returns a pointer to the &media_devnode 155 * 156 * @filp: pointer to struct &file 157 */ 158static inline struct media_devnode *media_devnode_data(struct file *filp) 159{ 160 return filp->private_data; 161} 162 163/** 164 * media_devnode_is_registered - returns true if &media_devnode is registered; 165 * false otherwise. 166 * 167 * @devnode: pointer to struct &media_devnode. 168 * 169 * Note: If mdev is NULL, it also returns false. 170 */ 171static inline int media_devnode_is_registered(struct media_devnode *devnode) 172{ 173 if (!devnode) 174 return false; 175 176 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); 177} 178 179#endif /* _MEDIA_DEVNODE_H */ 180