LXR linux/include/media/media-devnode.h

   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
  36/*
  37 * Flag to mark the media_devnode struct as registered. Drivers must not touch
  38 * this flag directly, it will be set and cleared by media_devnode_register and
  39 * media_devnode_unregister.
  40 */
  41#define MEDIA_FLAG_REGISTERED   0
  42
  43/**
  44 * struct media_file_operations - Media device file operations
  45 *
  46 * @owner: should be filled with %THIS_MODULE
  47 * @read: pointer to the function that implements read() syscall
  48 * @write: pointer to the function that implements write() syscall
  49 * @poll: pointer to the function that implements poll() syscall
  50 * @ioctl: pointer to the function that implements ioctl() syscall
  51 * @compat_ioctl: pointer to the function that will handle 32 bits userspace
  52 *      calls to the the ioctl() syscall on a Kernel compiled with 64 bits.
  53 * @open: pointer to the function that implements open() syscall
  54 * @release: pointer to the function that will release the resources allocated
  55 *      by the @open function.
  56 */
  57struct media_file_operations {
  58        struct module *owner;
  59        ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
  60        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
  61        unsigned int (*poll) (struct file *, struct poll_table_struct *);
  62        long (*ioctl) (struct file *, unsigned int, unsigned long);
  63        long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
  64        int (*open) (struct file *);
  65        int (*release) (struct file *);
  66};
  67
  68/**
  69 * struct media_devnode - Media device node
  70 * @fops:       pointer to struct &media_file_operations with media device ops
  71 * @dev:        struct device pointer for the media controller device
  72 * @cdev:       struct cdev pointer character device
  73 * @parent:     parent device
  74 * @minor:      device node minor number
  75 * @flags:      flags, combination of the MEDIA_FLAG_* constants
  76 * @release:    release callback called at the end of media_devnode_release()
  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        /* device ops */
  85        const struct media_file_operations *fops;
  86
  87        /* sysfs */
  88        struct device dev;              /* media device */
  89        struct cdev cdev;               /* character device */
  90        struct device *parent;          /* device parent */
  91
  92        /* device info */
  93        int minor;
  94        unsigned long flags;            /* Use bitops to access flags */
  95
  96        /* callbacks */
  97        void (*release)(struct media_devnode *mdev);
  98};
  99
 100/* dev to media_devnode */
 101#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
 102
 103/**
 104 * media_devnode_register - register a media device node
 105 *
 106 * @mdev: media device node structure we want to register
 107 * @owner: should be filled with %THIS_MODULE
 108 *
 109 * The registration code assigns minor numbers and registers the new device node
 110 * with the kernel. An error is returned if no free minor number can be found,
 111 * or if the registration of the device node fails.
 112 *
 113 * Zero is returned on success.
 114 *
 115 * Note that if the media_devnode_register call fails, the release() callback of
 116 * the media_devnode structure is *not* called, so the caller is responsible for
 117 * freeing any data.
 118 */
 119int __must_check media_devnode_register(struct media_devnode *mdev,
 120                                        struct module *owner);
 121
 122/**
 123 * media_devnode_unregister - unregister a media device node
 124 * @mdev: the device node to unregister
 125 *
 126 * This unregisters the passed device. Future open calls will be met with
 127 * errors.
 128 *
 129 * This function can safely be called if the device node has never been
 130 * registered or has already been unregistered.
 131 */
 132void media_devnode_unregister(struct media_devnode *mdev);
 133
 134/**
 135 * media_devnode_data - returns a pointer to the &media_devnode
 136 *
 137 * @filp: pointer to struct &file
 138 */
 139static inline struct media_devnode *media_devnode_data(struct file *filp)
 140{
 141        return filp->private_data;
 142}
 143
 144/**
 145 * media_devnode_is_registered - returns true if &media_devnode is registered;
 146 *      false otherwise.
 147 *
 148 * @mdev: pointer to struct &media_devnode.
 149 */
 150static inline int media_devnode_is_registered(struct media_devnode *mdev)
 151{
 152        return test_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);
 153}
 154
 155#endif /* _MEDIA_DEVNODE_H */
 156