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 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 */ media_devnode_data(struct file * filp)147 static inline struct media_devnode *media_devnode_data(struct file *filp) 148 { 149 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 */ media_devnode_is_registered(struct media_devnode * devnode)160 static inline int media_devnode_is_registered(struct media_devnode *devnode) 161 { 162 if (!devnode) 163 return false; 164 165 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); 166 } 167 168 #endif /* _MEDIA_DEVNODE_H */ 169