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