169 строки
5.3 KiB
C
169 строки
5.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Media device node
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*
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* Copyright (C) 2010 Nokia Corporation
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*
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* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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* Sakari Ailus <sakari.ailus@iki.fi>
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*
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* --
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*
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* Common functions for media-related drivers to register and unregister media
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* device nodes.
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*/
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#ifndef _MEDIA_DEVNODE_H
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#define _MEDIA_DEVNODE_H
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#include <linux/poll.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/cdev.h>
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struct media_device;
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/*
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* Flag to mark the media_devnode struct as registered. Drivers must not touch
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* this flag directly, it will be set and cleared by media_devnode_register and
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* media_devnode_unregister.
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*/
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#define MEDIA_FLAG_REGISTERED 0
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/**
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* struct media_file_operations - Media device file operations
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*
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* @owner: should be filled with %THIS_MODULE
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* @read: pointer to the function that implements read() syscall
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* @write: pointer to the function that implements write() syscall
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* @poll: pointer to the function that implements poll() syscall
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* @ioctl: pointer to the function that implements ioctl() syscall
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* @compat_ioctl: pointer to the function that will handle 32 bits userspace
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* calls to the the ioctl() syscall on a Kernel compiled with 64 bits.
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* @open: pointer to the function that implements open() syscall
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* @release: pointer to the function that will release the resources allocated
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* by the @open function.
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*/
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struct media_file_operations {
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struct module *owner;
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ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
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ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
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__poll_t (*poll) (struct file *, struct poll_table_struct *);
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long (*ioctl) (struct file *, unsigned int, unsigned long);
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long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
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int (*open) (struct file *);
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int (*release) (struct file *);
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};
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/**
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* struct media_devnode - Media device node
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* @media_dev: pointer to struct &media_device
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* @fops: pointer to struct &media_file_operations with media device ops
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* @dev: pointer to struct &device containing the media controller device
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* @cdev: struct cdev pointer character device
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* @parent: parent device
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* @minor: device node minor number
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* @flags: flags, combination of the ``MEDIA_FLAG_*`` constants
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* @release: release callback called at the end of ``media_devnode_release()``
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* routine at media-device.c.
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*
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* This structure represents a media-related device node.
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*
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* The @parent is a physical device. It must be set by core or device drivers
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* before registering the node.
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*/
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struct media_devnode {
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struct media_device *media_dev;
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/* device ops */
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const struct media_file_operations *fops;
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/* sysfs */
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struct device dev; /* media device */
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struct cdev cdev; /* character device */
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struct device *parent; /* device parent */
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/* device info */
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int minor;
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unsigned long flags; /* Use bitops to access flags */
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/* callbacks */
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void (*release)(struct media_devnode *devnode);
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};
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/* dev to media_devnode */
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#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
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/**
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* media_devnode_register - register a media device node
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*
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* @mdev: struct media_device we want to register a device node
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* @devnode: media device node structure we want to register
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* @owner: should be filled with %THIS_MODULE
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*
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* The registration code assigns minor numbers and registers the new device node
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* with the kernel. An error is returned if no free minor number can be found,
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* or if the registration of the device node fails.
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*
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* Zero is returned on success.
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*
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* Note that if the media_devnode_register call fails, the release() callback of
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* the media_devnode structure is *not* called, so the caller is responsible for
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* freeing any data.
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*/
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int __must_check media_devnode_register(struct media_device *mdev,
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struct media_devnode *devnode,
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struct module *owner);
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/**
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* media_devnode_unregister_prepare - clear the media device node register bit
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* @devnode: the device node to prepare for unregister
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*
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* This clears the passed device register bit. Future open calls will be met
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* with errors. Should be called before media_devnode_unregister() to avoid
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* races with unregister and device file open calls.
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*
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* This function can safely be called if the device node has never been
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* registered or has already been unregistered.
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*/
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void media_devnode_unregister_prepare(struct media_devnode *devnode);
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/**
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* media_devnode_unregister - unregister a media device node
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* @devnode: the device node to unregister
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*
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* This unregisters the passed device. Future open calls will be met with
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* errors.
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*
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* Should be called after media_devnode_unregister_prepare()
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*/
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void media_devnode_unregister(struct media_devnode *devnode);
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/**
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* media_devnode_data - returns a pointer to the &media_devnode
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*
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* @filp: pointer to struct &file
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*/
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static inline struct media_devnode *media_devnode_data(struct file *filp)
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{
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return filp->private_data;
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}
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/**
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* media_devnode_is_registered - returns true if &media_devnode is registered;
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* false otherwise.
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*
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* @devnode: pointer to struct &media_devnode.
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*
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* Note: If mdev is NULL, it also returns false.
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*/
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static inline int media_devnode_is_registered(struct media_devnode *devnode)
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{
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if (!devnode)
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return false;
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return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
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}
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#endif /* _MEDIA_DEVNODE_H */
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