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 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 * @media_dev: pointer to struct &media_device 73 * @fops: pointer to struct &media_file_operations with media device ops 74 * @dev: pointer to struct &device containing the media controller device 75 * @cdev: struct cdev pointer character device 76 * @parent: parent device 77 * @minor: device node minor number 78 * @flags: flags, combination of the ``MEDIA_FLAG_*`` constants 79 * @release: release callback called at the end of ``media_devnode_release()`` 80 * routine at media-device.c. 81 * 82 * This structure represents a media-related device node. 83 * 84 * The @parent is a physical device. It must be set by core or device drivers 85 * before registering the node. 86 */ 87 struct media_devnode { 88 struct media_device *media_dev; 89 90 /* device ops */ 91 const struct media_file_operations *fops; 92 93 /* sysfs */ 94 struct device dev; /* media device */ 95 struct cdev cdev; /* character device */ 96 struct device *parent; /* device parent */ 97 98 /* device info */ 99 int minor; 100 unsigned long flags; /* Use bitops to access flags */ 101 102 /* callbacks */ 103 void (*release)(struct media_devnode *devnode); 104 }; 105 106 /* dev to media_devnode */ 107 #define to_media_devnode(cd) container_of(cd, struct media_devnode, dev) 108 109 /** 110 * media_devnode_register - register a media device node 111 * 112 * @mdev: struct media_device we want to register a device node 113 * @devnode: media device node structure we want to register 114 * @owner: should be filled with %THIS_MODULE 115 * 116 * The registration code assigns minor numbers and registers the new device node 117 * with the kernel. An error is returned if no free minor number can be found, 118 * or if the registration of the device node fails. 119 * 120 * Zero is returned on success. 121 * 122 * Note that if the media_devnode_register call fails, the release() callback of 123 * the media_devnode structure is *not* called, so the caller is responsible for 124 * freeing any data. 125 */ 126 int __must_check media_devnode_register(struct media_device *mdev, 127 struct media_devnode *devnode, 128 struct module *owner); 129 130 /** 131 * media_devnode_unregister_prepare - clear the media device node register bit 132 * @devnode: the device node to prepare for unregister 133 * 134 * This clears the passed device register bit. Future open calls will be met 135 * with errors. Should be called before media_devnode_unregister() to avoid 136 * races with unregister and device file open calls. 137 * 138 * This function can safely be called if the device node has never been 139 * registered or has already been unregistered. 140 */ 141 void media_devnode_unregister_prepare(struct media_devnode *devnode); 142 143 /** 144 * media_devnode_unregister - unregister a media device node 145 * @devnode: the device node to unregister 146 * 147 * This unregisters the passed device. Future open calls will be met with 148 * errors. 149 * 150 * Should be called after media_devnode_unregister_prepare() 151 */ 152 void media_devnode_unregister(struct media_devnode *devnode); 153 154 /** 155 * media_devnode_data - returns a pointer to the &media_devnode 156 * 157 * @filp: pointer to struct &file 158 */ 159 static inline struct media_devnode *media_devnode_data(struct file *filp) 160 { 161 return filp->private_data; 162 } 163 164 /** 165 * media_devnode_is_registered - returns true if &media_devnode is registered; 166 * false otherwise. 167 * 168 * @devnode: pointer to struct &media_devnode. 169 * 170 * Note: If mdev is NULL, it also returns false. 171 */ 172 static inline int media_devnode_is_registered(struct media_devnode *devnode) 173 { 174 if (!devnode) 175 return false; 176 177 return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags); 178 } 179 180 #endif /* _MEDIA_DEVNODE_H */ 181