| 1 | |
| 2 | * Media device node
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| 3 | *
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| 4 | * Copyright (C) 2010 Nokia Corporation
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| 5 | *
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| 6 | * Contacts: Laurent Pinchart <[email protected]>
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| 7 | * Sakari Ailus <[email protected]>
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| 8 | *
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| 9 | * This program is free software; you can redistribute it and/or modify
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| 10 | * it under the terms of the GNU General Public License version 2 as
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| 11 | * published by the Free Software Foundation.
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| 12 | *
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| 13 | * This program is distributed in the hope that it will be useful,
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| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | * GNU General Public License for more details.
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| 17 | *
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| 18 | * You should have received a copy of the GNU General Public License
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| 19 | * along with this program; if not, write to the Free Software
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| 20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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| 21 | *
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| 22 | * --
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| 23 | *
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| 24 | * Common functions for media-related drivers to register and unregister media
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| 25 | * device nodes.
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| 26 |
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| 27 |
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| 28 | #ifndef _MEDIA_DEVNODE_H
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| 29 | #define _MEDIA_DEVNODE_H
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| 30 |
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| 31 | #include <linux/poll.h>
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| 32 | #include <linux/fs.h>
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| 33 | #include <linux/device.h>
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| 34 | #include <linux/cdev.h>
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| 35 |
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| 36 | struct media_device;
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| 37 |
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| 38 | |
| 39 | * Flag to mark the media_devnode struct as registered. Drivers must not touch
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| 40 | * this flag directly, it will be set and cleared by media_devnode_register and
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| 41 | * media_devnode_unregister.
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| 42 |
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| 43 | #define MEDIA_FLAG_REGISTERED 0
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| 44 |
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| 45 | |
| 46 | * struct media_file_operations - Media device file operations
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| 47 | *
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| 48 | * @owner: should be filled with %THIS_MODULE
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| 49 | * @read: pointer to the function that implements read() syscall
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| 50 | * @write: pointer to the function that implements write() syscall
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| 51 | * @poll: pointer to the function that implements poll() syscall
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| 52 | * @ioctl: pointer to the function that implements ioctl() syscall
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| 53 | * @compat_ioctl: pointer to the function that will handle 32 bits userspace
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| 54 | * calls to the the ioctl() syscall on a Kernel compiled with 64 bits.
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| 55 | * @open: pointer to the function that implements open() syscall
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| 56 | * @release: pointer to the function that will release the resources allocated
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| 57 | * by the @open function.
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| 58 |
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| 59 | struct media_file_operations {
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| 60 | struct module *owner;
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| 61 | ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
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| 62 | ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
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| 63 | unsigned int (*poll) (struct file *, struct poll_table_struct *);
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| 64 | long (*ioctl) (struct file *, unsigned int, unsigned long);
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| 65 | long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
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| 66 | int (*open) (struct file *);
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| 67 | int (*release) (struct file *);
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| 68 | };
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| 69 |
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| 70 | |
| 71 | * struct media_devnode - Media device node
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| 72 | * @media_dev: pointer to struct &media_device
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| 73 | * @fops: pointer to struct &media_file_operations with media device ops
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| 74 | * @dev: pointer to struct &device containing the media controller device
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| 75 | * @cdev: struct cdev pointer character device
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| 76 | * @parent: parent device
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| 77 | * @minor: device node minor number
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| 78 | * @flags: flags, combination of the MEDIA_FLAG_* constants
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| 79 | * @release: release callback called at the end of media_devnode_release()
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| 80 | *
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| 81 | * This structure represents a media-related device node.
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| 82 | *
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| 83 | * The @parent is a physical device. It must be set by core or device drivers
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| 84 | * before registering the node.
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| 85 |
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| 86 | struct media_devnode {
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| 87 | struct media_device *media_dev;
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| 88 |
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| 89 |
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| 90 | const struct media_file_operations *fops;
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| 91 |
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| 92 |
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| 93 | struct device dev;
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| 94 | struct cdev cdev;
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| 95 | struct device *parent;
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| 96 |
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| 97 |
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| 98 | int minor;
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| 99 | unsigned long flags;
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| 100 |
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| 101 |
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| 102 | void (*release)(struct media_devnode *devnode);
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| 103 | };
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| 104 |
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| 105 |
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| 106 | #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
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| 107 |
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| 108 | |
| 109 | * media_devnode_register - register a media device node
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| 110 | *
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| 111 | * @mdev: struct media_device we want to register a device node
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| 112 | * @devnode: media device node structure we want to register
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| 113 | * @owner: should be filled with %THIS_MODULE
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| 114 | *
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| 115 | * The registration code assigns minor numbers and registers the new device node
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| 116 | * with the kernel. An error is returned if no free minor number can be found,
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| 117 | * or if the registration of the device node fails.
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| 118 | *
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| 119 | * Zero is returned on success.
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| 120 | *
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| 121 | * Note that if the media_devnode_register call fails, the release() callback of
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| 122 | * the media_devnode structure is *not* called, so the caller is responsible for
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| 123 | * freeing any data.
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| 124 |
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| 125 | int __must_check media_devnode_register(struct media_device *mdev,
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| 126 | struct media_devnode *devnode,
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| 127 | struct module *owner);
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| 128 |
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| 129 | |
| 130 | * media_devnode_unregister_prepare - clear the media device node register bit
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| 131 | * @devnode: the device node to prepare for unregister
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| 132 | *
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| 133 | * This clears the passed device register bit. Future open calls will be met
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| 134 | * with errors. Should be called before media_devnode_unregister() to avoid
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| 135 | * races with unregister and device file open calls.
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| 136 | *
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| 137 | * This function can safely be called if the device node has never been
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| 138 | * registered or has already been unregistered.
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| 139 |
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| 140 | void media_devnode_unregister_prepare(struct media_devnode *devnode);
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| 141 |
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| 142 | |
| 143 | * media_devnode_unregister - unregister a media device node
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| 144 | * @devnode: the device node to unregister
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| 145 | *
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| 146 | * This unregisters the passed device. Future open calls will be met with
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| 147 | * errors.
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| 148 | *
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| 149 | * Should be called after media_devnode_unregister_prepare()
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| 150 |
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| 151 | void media_devnode_unregister(struct media_devnode *devnode);
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| 152 |
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| 153 | |
| 154 | * media_devnode_data - returns a pointer to the &media_devnode
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| 155 | *
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| 156 | * @filp: pointer to struct &file
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| 157 |
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| 158 | static inline struct media_devnode *media_devnode_data(struct file *filp)
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| 159 | {
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| 160 | return filp->private_data;
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| 161 | }
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| 162 |
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| 163 | |
| 164 | * media_devnode_is_registered - returns true if &media_devnode is registered;
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| 165 | * false otherwise.
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| 166 | *
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| 167 | * @devnode: pointer to struct &media_devnode.
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| 168 | *
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| 169 | * Note: If mdev is NULL, it also returns false.
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| 170 |
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| 171 | static inline int media_devnode_is_registered(struct media_devnode *devnode)
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| 172 | {
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| 173 | if (!devnode)
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| 174 | return false;
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| 175 |
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| 176 | return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
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| 177 | }
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| 178 |
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| 179 | #endif
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