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 struct media_device; 37 38 /* 39 * Flag to mark the media_devnode struct as registered. Drivers must not touch 40 * this flag directly, it will be set and cleared by media_devnode_register and 41 * media_devnode_unregister. 42 */ 43 #define MEDIA_FLAG_REGISTERED 0 44 45 /** 46 * struct media_file_operations - Media device file operations 47 * 48 * @owner: should be filled with %THIS_MODULE 49 * @read: pointer to the function that implements read() syscall 50 * @write: pointer to the function that implements write() syscall 51 * @poll: pointer to the function that implements poll() syscall 52 * @ioctl: pointer to the function that implements ioctl() syscall 53 * @compat_ioctl: pointer to the function that will handle 32 bits userspace 54 * calls to the the ioctl() syscall on a Kernel compiled with 64 bits. 55 * @open: pointer to the function that implements open() syscall 56 * @release: pointer to the function that will release the resources allocated 57 * by the @open function. 58 */ 59 struct media_file_operations { 60 struct module *owner; 61 ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 62 ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 63 unsigned int (*poll) (struct file *, struct poll_table_struct *); 64 long (*ioctl) (struct file *, unsigned int, unsigned long); 65 long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 66 int (*open) (struct file *); 67 int (*release) (struct file *); 68 }; 69 70 /** 71 * struct media_devnode - Media device node 72 * @fops: pointer to struct &media_file_operations with media device ops 73 * @dev: struct device pointer for the media controller device 74 * @cdev: struct cdev pointer character device 75 * @parent: parent device 76 * @minor: device node minor number 77 * @flags: flags, combination of the MEDIA_FLAG_* constants 78 * @release: release callback called at the end of media_devnode_release() 79 * 80 * This structure represents a media-related device node. 81 * 82 * The @parent is a physical device. It must be set by core or device drivers 83 * before registering the node. 84 */ 85 struct media_devnode { 86 struct media_device *media_dev; 87 88 /* device ops */ 89 const struct media_file_operations *fops; 90 91 /* sysfs */ 92 struct device dev; /* media device */ 93 struct cdev cdev; /* character device */ 94 struct device *parent; /* device parent */ 95 96 /* device info */ 97 int minor; 98 unsigned long flags; /* Use bitops to access flags */ 99 100 /* callbacks */ 101 void (*release)(struct media_devnode *devnode); 102 }; 103 104 /* dev to media_devnode */ 105 #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 106 107 /** 108 * media_devnode_register - register a media device node 109 * 110 * @media_dev: struct media_device we want to register a device node 111 * @devnode: media device node structure we want to register 112 * @owner: should be filled with %THIS_MODULE 113 * 114 * The registration code assigns minor numbers and registers the new device node 115 * with the kernel. An error is returned if no free minor number can be found, 116 * or if the registration of the device node fails. 117 * 118 * Zero is returned on success. 119 * 120 * Note that if the media_devnode_register call fails, the release() callback of 121 * the media_devnode structure is *not* called, so the caller is responsible for 122 * freeing any data. 123 */ 124 int __must_check media_devnode_register(struct media_device *mdev, 125 struct media_devnode *devnode, 126 struct module *owner); 127 128 /** 129 * media_devnode_unregister_prepare - clear the media device node register bit 130 * @devnode: the device node to prepare for unregister 131 * 132 * This clears the passed device register bit. Future open calls will be met 133 * with errors. Should be called before media_devnode_unregister() to avoid 134 * races with unregister and device file open calls. 135 * 136 * This function can safely be called if the device node has never been 137 * registered or has already been unregistered. 138 */ 139 void media_devnode_unregister_prepare(struct media_devnode *devnode); 140 141 /** 142 * media_devnode_unregister - unregister a media device node 143 * @devnode: the device node to unregister 144 * 145 * This unregisters the passed device. Future open calls will be met with 146 * errors. 147 * 148 * Should be called after media_devnode_unregister_prepare() 149 */ 150 void media_devnode_unregister(struct media_devnode *devnode); 151 152 /** 153 * media_devnode_data - returns a pointer to the &media_devnode 154 * 155 * @filp: pointer to struct &file 156 */ 157 static inline struct media_devnode *media_devnode_data(struct file *filp) 158 { 159 return filp->private_data; 160 } 161 162 /** 163 * media_devnode_is_registered - returns true if &media_devnode is registered; 164 * false otherwise. 165 * 166 * @devnode: pointer to struct &media_devnode. 167 * 168 * Note: If mdev is NULL, it also returns false. 169 */ 170 static inline int media_devnode_is_registered(struct media_devnode *devnode) 171 { 172 if (!devnode) 173 return false; 174 175 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); 176 } 177 178 #endif /* _MEDIA_DEVNODE_H */ 179