1 /* 2 * Media device node 3 * 4 * Copyright (C) 2010 Nokia Corporation 5 * 6 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com> 7 * Sakari Ailus <sakari.ailus@iki.fi> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 21 * 22 * -- 23 * 24 * Common functions for media-related drivers to register and unregister media 25 * device nodes. 26 */ 27 28 #ifndef _MEDIA_DEVNODE_H 29 #define _MEDIA_DEVNODE_H 30 31 #include <linux/poll.h> 32 #include <linux/fs.h> 33 #include <linux/device.h> 34 #include <linux/cdev.h> 35 36 /* 37 * Flag to mark the media_devnode struct as registered. Drivers must not touch 38 * this flag directly, it will be set and cleared by media_devnode_register and 39 * media_devnode_unregister. 40 */ 41 #define MEDIA_FLAG_REGISTERED 0 42 43 /** 44 * struct media_file_operations - Media device file operations 45 * 46 * @owner: should be filled with %THIS_MODULE 47 * @read: pointer to the function that implements read() syscall 48 * @write: pointer to the function that implements write() syscall 49 * @poll: pointer to the function that implements poll() syscall 50 * @ioctl: pointer to the function that implements ioctl() syscall 51 * @compat_ioctl: pointer to the function that will handle 32 bits userspace 52 * calls to the the ioctl() syscall on a Kernel compiled with 64 bits. 53 * @open: pointer to the function that implements open() syscall 54 * @release: pointer to the function that will release the resources allocated 55 * by the @open function. 56 */ 57 struct media_file_operations { 58 struct module *owner; 59 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 60 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 61 unsigned int (*poll) (struct file *, struct poll_table_struct *); 62 long (*ioctl) (struct file *, unsigned int, unsigned long); 63 long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 64 int (*open) (struct file *); 65 int (*release) (struct file *); 66 }; 67 68 /** 69 * struct media_devnode - Media device node 70 * @fops: pointer to struct &media_file_operations with media device ops 71 * @dev: struct device pointer for the media controller device 72 * @cdev: struct cdev pointer character device 73 * @parent: parent device 74 * @minor: device node minor number 75 * @flags: flags, combination of the MEDIA_FLAG_* constants 76 * @release: release callback called at the end of media_devnode_release() 77 * 78 * This structure represents a media-related device node. 79 * 80 * The @parent is a physical device. It must be set by core or device drivers 81 * before registering the node. 82 */ 83 struct media_devnode { 84 /* device ops */ 85 const struct media_file_operations *fops; 86 87 /* sysfs */ 88 struct device dev; /* media device */ 89 struct cdev cdev; /* character device */ 90 struct device *parent; /* device parent */ 91 92 /* device info */ 93 int minor; 94 unsigned long flags; /* Use bitops to access flags */ 95 96 /* callbacks */ 97 void (*release)(struct media_devnode *mdev); 98 }; 99 100 /* dev to media_devnode */ 101 #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 102 103 /** 104 * media_devnode_register - register a media device node 105 * 106 * @mdev: media device node structure we want to register 107 * @owner: should be filled with %THIS_MODULE 108 * 109 * The registration code assigns minor numbers and registers the new device node 110 * with the kernel. An error is returned if no free minor number can be found, 111 * or if the registration of the device node fails. 112 * 113 * Zero is returned on success. 114 * 115 * Note that if the media_devnode_register call fails, the release() callback of 116 * the media_devnode structure is *not* called, so the caller is responsible for 117 * freeing any data. 118 */ 119 int __must_check media_devnode_register(struct media_devnode *mdev, 120 struct module *owner); 121 122 /** 123 * media_devnode_unregister - unregister a media device node 124 * @mdev: the device node to unregister 125 * 126 * This unregisters the passed device. Future open calls will be met with 127 * errors. 128 * 129 * This function can safely be called if the device node has never been 130 * registered or has already been unregistered. 131 */ 132 void media_devnode_unregister(struct media_devnode *mdev); 133 134 /** 135 * media_devnode_data - returns a pointer to the &media_devnode 136 * 137 * @filp: pointer to struct &file 138 */ 139 static inline struct media_devnode *media_devnode_data(struct file *filp) 140 { 141 return filp->private_data; 142 } 143 144 /** 145 * media_devnode_is_registered - returns true if &media_devnode is registered; 146 * false otherwise. 147 * 148 * @mdev: pointer to struct &media_devnode. 149 */ 150 static inline int media_devnode_is_registered(struct media_devnode *mdev) 151 { 152 return test_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); 153 } 154 155 #endif /* _MEDIA_DEVNODE_H */ 156