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       1                 :            : /* SPDX-License-Identifier: GPL-2.0-only */
       2                 :            : /*
       3                 :            :  * Media device node
       4                 :            :  *
       5                 :            :  * Copyright (C) 2010 Nokia Corporation
       6                 :            :  *
       7                 :            :  * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
       8                 :            :  *           Sakari Ailus <sakari.ailus@iki.fi>
       9                 :            :  *
      10                 :            :  * --
      11                 :            :  *
      12                 :            :  * Common functions for media-related drivers to register and unregister media
      13                 :            :  * device nodes.
      14                 :            :  */
      15                 :            : 
      16                 :            : #ifndef _MEDIA_DEVNODE_H
      17                 :            : #define _MEDIA_DEVNODE_H
      18                 :            : 
      19                 :            : #include <linux/poll.h>
      20                 :            : #include <linux/fs.h>
      21                 :            : #include <linux/device.h>
      22                 :            : #include <linux/cdev.h>
      23                 :            : 
      24                 :            : struct media_device;
      25                 :            : 
      26                 :            : /*
      27                 :            :  * Flag to mark the media_devnode struct as registered. Drivers must not touch
      28                 :            :  * this flag directly, it will be set and cleared by media_devnode_register and
      29                 :            :  * media_devnode_unregister.
      30                 :            :  */
      31                 :            : #define MEDIA_FLAG_REGISTERED   0
      32                 :            : 
      33                 :            : /**
      34                 :            :  * struct media_file_operations - Media device file operations
      35                 :            :  *
      36                 :            :  * @owner: should be filled with %THIS_MODULE
      37                 :            :  * @read: pointer to the function that implements read() syscall
      38                 :            :  * @write: pointer to the function that implements write() syscall
      39                 :            :  * @poll: pointer to the function that implements poll() syscall
      40                 :            :  * @ioctl: pointer to the function that implements ioctl() syscall
      41                 :            :  * @compat_ioctl: pointer to the function that will handle 32 bits userspace
      42                 :            :  *      calls to the the ioctl() syscall on a Kernel compiled with 64 bits.
      43                 :            :  * @open: pointer to the function that implements open() syscall
      44                 :            :  * @release: pointer to the function that will release the resources allocated
      45                 :            :  *      by the @open function.
      46                 :            :  */
      47                 :            : struct media_file_operations {
      48                 :            :         struct module *owner;
      49                 :            :         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
      50                 :            :         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
      51                 :            :         __poll_t (*poll) (struct file *, struct poll_table_struct *);
      52                 :            :         long (*ioctl) (struct file *, unsigned int, unsigned long);
      53                 :            :         long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
      54                 :            :         int (*open) (struct file *);
      55                 :            :         int (*release) (struct file *);
      56                 :            : };
      57                 :            : 
      58                 :            : /**
      59                 :            :  * struct media_devnode - Media device node
      60                 :            :  * @media_dev:  pointer to struct &media_device
      61                 :            :  * @fops:       pointer to struct &media_file_operations with media device ops
      62                 :            :  * @dev:        pointer to struct &device containing the media controller device
      63                 :            :  * @cdev:       struct cdev pointer character device
      64                 :            :  * @parent:     parent device
      65                 :            :  * @minor:      device node minor number
      66                 :            :  * @flags:      flags, combination of the ``MEDIA_FLAG_*`` constants
      67                 :            :  * @release:    release callback called at the end of ``media_devnode_release()``
      68                 :            :  *              routine at media-device.c.
      69                 :            :  *
      70                 :            :  * This structure represents a media-related device node.
      71                 :            :  *
      72                 :            :  * The @parent is a physical device. It must be set by core or device drivers
      73                 :            :  * before registering the node.
      74                 :            :  */
      75                 :            : struct media_devnode {
      76                 :            :         struct media_device *media_dev;
      77                 :            : 
      78                 :            :         /* device ops */
      79                 :            :         const struct media_file_operations *fops;
      80                 :            : 
      81                 :            :         /* sysfs */
      82                 :            :         struct device dev;              /* media device */
      83                 :            :         struct cdev cdev;               /* character device */
      84                 :            :         struct device *parent;          /* device parent */
      85                 :            : 
      86                 :            :         /* device info */
      87                 :            :         int minor;
      88                 :            :         unsigned long flags;            /* Use bitops to access flags */
      89                 :            : 
      90                 :            :         /* callbacks */
      91                 :            :         void (*release)(struct media_devnode *devnode);
      92                 :            : };
      93                 :            : 
      94                 :            : /* dev to media_devnode */
      95                 :            : #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
      96                 :            : 
      97                 :            : /**
      98                 :            :  * media_devnode_register - register a media device node
      99                 :            :  *
     100                 :            :  * @mdev: struct media_device we want to register a device node
     101                 :            :  * @devnode: media device node structure we want to register
     102                 :            :  * @owner: should be filled with %THIS_MODULE
     103                 :            :  *
     104                 :            :  * The registration code assigns minor numbers and registers the new device node
     105                 :            :  * with the kernel. An error is returned if no free minor number can be found,
     106                 :            :  * or if the registration of the device node fails.
     107                 :            :  *
     108                 :            :  * Zero is returned on success.
     109                 :            :  *
     110                 :            :  * Note that if the media_devnode_register call fails, the release() callback of
     111                 :            :  * the media_devnode structure is *not* called, so the caller is responsible for
     112                 :            :  * freeing any data.
     113                 :            :  */
     114                 :            : int __must_check media_devnode_register(struct media_device *mdev,
     115                 :            :                                         struct media_devnode *devnode,
     116                 :            :                                         struct module *owner);
     117                 :            : 
     118                 :            : /**
     119                 :            :  * media_devnode_unregister_prepare - clear the media device node register bit
     120                 :            :  * @devnode: the device node to prepare for unregister
     121                 :            :  *
     122                 :            :  * This clears the passed device register bit. Future open calls will be met
     123                 :            :  * with errors. Should be called before media_devnode_unregister() to avoid
     124                 :            :  * races with unregister and device file open calls.
     125                 :            :  *
     126                 :            :  * This function can safely be called if the device node has never been
     127                 :            :  * registered or has already been unregistered.
     128                 :            :  */
     129                 :            : void media_devnode_unregister_prepare(struct media_devnode *devnode);
     130                 :            : 
     131                 :            : /**
     132                 :            :  * media_devnode_unregister - unregister a media device node
     133                 :            :  * @devnode: the device node to unregister
     134                 :            :  *
     135                 :            :  * This unregisters the passed device. Future open calls will be met with
     136                 :            :  * errors.
     137                 :            :  *
     138                 :            :  * Should be called after media_devnode_unregister_prepare()
     139                 :            :  */
     140                 :            : void media_devnode_unregister(struct media_devnode *devnode);
     141                 :            : 
     142                 :            : /**
     143                 :            :  * media_devnode_data - returns a pointer to the &media_devnode
     144                 :            :  *
     145                 :            :  * @filp: pointer to struct &file
     146                 :            :  */
     147                 :            : static inline struct media_devnode *media_devnode_data(struct file *filp)
     148                 :            : {
     149                 :          0 :         return filp->private_data;
     150                 :            : }
     151                 :            : 
     152                 :            : /**
     153                 :            :  * media_devnode_is_registered - returns true if &media_devnode is registered;
     154                 :            :  *      false otherwise.
     155                 :            :  *
     156                 :            :  * @devnode: pointer to struct &media_devnode.
     157                 :            :  *
     158                 :            :  * Note: If mdev is NULL, it also returns false.
     159                 :            :  */
     160                 :            : static inline int media_devnode_is_registered(struct media_devnode *devnode)
     161                 :            : {
     162                 :          0 :         if (!devnode)
     163                 :            :                 return false;
     164                 :            : 
     165                 :            :         return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
     166                 :            : }
     167                 :            : 
     168                 :            : #endif /* _MEDIA_DEVNODE_H */