1 /* 2 * Media device node 3 * 4 * Copyright (C) 2010 Nokia Corporation 5 * 6 * Contacts: Laurent Pinchart <[email protected]> 7 * Sakari Ailus <[email protected]> 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 struct media_file_operations { 44 struct module *owner; 45 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 46 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 47 unsigned int (*poll) (struct file *, struct poll_table_struct *); 48 long (*ioctl) (struct file *, unsigned int, unsigned long); 49 long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 50 int (*open) (struct file *); 51 int (*release) (struct file *); 52 }; 53 54 /** 55 * struct media_devnode - Media device node 56 * @fops: pointer to struct media_file_operations with media device ops 57 * @dev: struct device pointer for the media controller device 58 * @cdev: struct cdev pointer character device 59 * @parent: parent device 60 * @minor: device node minor number 61 * @flags: flags, combination of the MEDIA_FLAG_* constants 62 * @release: release callback called at the end of media_devnode_release() 63 * 64 * This structure represents a media-related device node. 65 * 66 * The @parent is a physical device. It must be set by core or device drivers 67 * before registering the node. 68 */ 69 struct media_devnode { 70 /* device ops */ 71 const struct media_file_operations *fops; 72 73 /* sysfs */ 74 struct device dev; /* media device */ 75 struct cdev cdev; /* character device */ 76 struct device *parent; /* device parent */ 77 78 /* device info */ 79 int minor; 80 unsigned long flags; /* Use bitops to access flags */ 81 82 /* callbacks */ 83 void (*release)(struct media_devnode *mdev); 84 }; 85 86 /* dev to media_devnode */ 87 #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 88 89 /** 90 * media_devnode_register - register a media device node 91 * 92 * @mdev: media device node structure we want to register 93 * @owner: should be filled with %THIS_MODULE 94 * 95 * The registration code assigns minor numbers and registers the new device node 96 * with the kernel. An error is returned if no free minor number can be found, 97 * or if the registration of the device node fails. 98 * 99 * Zero is returned on success. 100 * 101 * Note that if the media_devnode_register call fails, the release() callback of 102 * the media_devnode structure is *not* called, so the caller is responsible for 103 * freeing any data. 104 */ 105 int __must_check media_devnode_register(struct media_devnode *mdev, 106 struct module *owner); 107 108 /** 109 * media_devnode_unregister - unregister a media device node 110 * @mdev: the device node to unregister 111 * 112 * This unregisters the passed device. Future open calls will be met with 113 * errors. 114 * 115 * This function can safely be called if the device node has never been 116 * registered or has already been unregistered. 117 */ 118 void media_devnode_unregister(struct media_devnode *mdev); 119 120 static inline struct media_devnode *media_devnode_data(struct file *filp) 121 { 122 return filp->private_data; 123 } 124 125 static inline int media_devnode_is_registered(struct media_devnode *mdev) 126 { 127 return test_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); 128 } 129 130 #endif /* _MEDIA_DEVNODE_H */ 131