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168 lines
5.3 KiB
168 lines
5.3 KiB
/* 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 <[email protected]> |
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* Sakari Ailus <[email protected]> |
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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 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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