Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 1 | /* |
| 2 | * Media device node |
| 3 | * |
| 4 | * Copyright (C) 2010 Nokia Corporation |
| 5 | * |
| 6 | * Based on drivers/media/video/v4l2_dev.c code authored by |
| 7 | * Mauro Carvalho Chehab <mchehab@infradead.org> (version 2) |
| 8 | * Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1) |
| 9 | * |
| 10 | * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com> |
| 11 | * Sakari Ailus <sakari.ailus@iki.fi> |
| 12 | * |
| 13 | * This program is free software; you can redistribute it and/or modify |
| 14 | * it under the terms of the GNU General Public License version 2 as |
| 15 | * published by the Free Software Foundation. |
| 16 | * |
| 17 | * This program is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU General Public License |
| 23 | * along with this program; if not, write to the Free Software |
| 24 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 25 | * |
| 26 | * -- |
| 27 | * |
| 28 | * Generic media device node infrastructure to register and unregister |
| 29 | * character devices using a dynamic major number and proper reference |
| 30 | * counting. |
| 31 | */ |
| 32 | |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 33 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 34 | |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 35 | #include <linux/errno.h> |
| 36 | #include <linux/init.h> |
| 37 | #include <linux/module.h> |
| 38 | #include <linux/kernel.h> |
| 39 | #include <linux/kmod.h> |
| 40 | #include <linux/slab.h> |
| 41 | #include <linux/mm.h> |
| 42 | #include <linux/string.h> |
| 43 | #include <linux/types.h> |
| 44 | #include <linux/uaccess.h> |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 45 | |
| 46 | #include <media/media-devnode.h> |
| 47 | |
| 48 | #define MEDIA_NUM_DEVICES 256 |
| 49 | #define MEDIA_NAME "media" |
| 50 | |
| 51 | static dev_t media_dev_t; |
| 52 | |
| 53 | /* |
| 54 | * Active devices |
| 55 | */ |
| 56 | static DEFINE_MUTEX(media_devnode_lock); |
| 57 | static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES); |
| 58 | |
| 59 | /* Called when the last user of the media device exits. */ |
| 60 | static void media_devnode_release(struct device *cd) |
| 61 | { |
| 62 | struct media_devnode *mdev = to_media_devnode(cd); |
| 63 | |
| 64 | mutex_lock(&media_devnode_lock); |
| 65 | |
| 66 | /* Delete the cdev on this minor as well */ |
| 67 | cdev_del(&mdev->cdev); |
| 68 | |
| 69 | /* Mark device node number as free */ |
| 70 | clear_bit(mdev->minor, media_devnode_nums); |
| 71 | |
| 72 | mutex_unlock(&media_devnode_lock); |
| 73 | |
| 74 | /* Release media_devnode and perform other cleanups as needed. */ |
| 75 | if (mdev->release) |
| 76 | mdev->release(mdev); |
| 77 | } |
| 78 | |
| 79 | static struct bus_type media_bus_type = { |
| 80 | .name = MEDIA_NAME, |
| 81 | }; |
| 82 | |
| 83 | static ssize_t media_read(struct file *filp, char __user *buf, |
| 84 | size_t sz, loff_t *off) |
| 85 | { |
| 86 | struct media_devnode *mdev = media_devnode_data(filp); |
| 87 | |
| 88 | if (!mdev->fops->read) |
| 89 | return -EINVAL; |
| 90 | if (!media_devnode_is_registered(mdev)) |
| 91 | return -EIO; |
| 92 | return mdev->fops->read(filp, buf, sz, off); |
| 93 | } |
| 94 | |
| 95 | static ssize_t media_write(struct file *filp, const char __user *buf, |
| 96 | size_t sz, loff_t *off) |
| 97 | { |
| 98 | struct media_devnode *mdev = media_devnode_data(filp); |
| 99 | |
| 100 | if (!mdev->fops->write) |
| 101 | return -EINVAL; |
| 102 | if (!media_devnode_is_registered(mdev)) |
| 103 | return -EIO; |
| 104 | return mdev->fops->write(filp, buf, sz, off); |
| 105 | } |
| 106 | |
| 107 | static unsigned int media_poll(struct file *filp, |
| 108 | struct poll_table_struct *poll) |
| 109 | { |
| 110 | struct media_devnode *mdev = media_devnode_data(filp); |
| 111 | |
| 112 | if (!media_devnode_is_registered(mdev)) |
| 113 | return POLLERR | POLLHUP; |
| 114 | if (!mdev->fops->poll) |
| 115 | return DEFAULT_POLLMASK; |
| 116 | return mdev->fops->poll(filp, poll); |
| 117 | } |
| 118 | |
Sakari Ailus | c6c1d50 | 2013-01-22 12:27:55 -0300 | [diff] [blame] | 119 | static long |
| 120 | __media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg, |
| 121 | long (*ioctl_func)(struct file *filp, unsigned int cmd, |
| 122 | unsigned long arg)) |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 123 | { |
| 124 | struct media_devnode *mdev = media_devnode_data(filp); |
| 125 | |
Sakari Ailus | c6c1d50 | 2013-01-22 12:27:55 -0300 | [diff] [blame] | 126 | if (!ioctl_func) |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 127 | return -ENOTTY; |
| 128 | |
| 129 | if (!media_devnode_is_registered(mdev)) |
| 130 | return -EIO; |
| 131 | |
Sakari Ailus | c6c1d50 | 2013-01-22 12:27:55 -0300 | [diff] [blame] | 132 | return ioctl_func(filp, cmd, arg); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 133 | } |
| 134 | |
Sakari Ailus | c6c1d50 | 2013-01-22 12:27:55 -0300 | [diff] [blame] | 135 | static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 136 | { |
| 137 | struct media_devnode *mdev = media_devnode_data(filp); |
| 138 | |
| 139 | return __media_ioctl(filp, cmd, arg, mdev->fops->ioctl); |
| 140 | } |
| 141 | |
| 142 | #ifdef CONFIG_COMPAT |
| 143 | |
| 144 | static long media_compat_ioctl(struct file *filp, unsigned int cmd, |
| 145 | unsigned long arg) |
| 146 | { |
| 147 | struct media_devnode *mdev = media_devnode_data(filp); |
| 148 | |
| 149 | return __media_ioctl(filp, cmd, arg, mdev->fops->compat_ioctl); |
| 150 | } |
| 151 | |
| 152 | #endif /* CONFIG_COMPAT */ |
| 153 | |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 154 | /* Override for the open function */ |
| 155 | static int media_open(struct inode *inode, struct file *filp) |
| 156 | { |
| 157 | struct media_devnode *mdev; |
| 158 | int ret; |
| 159 | |
| 160 | /* Check if the media device is available. This needs to be done with |
| 161 | * the media_devnode_lock held to prevent an open/unregister race: |
| 162 | * without the lock, the device could be unregistered and freed between |
| 163 | * the media_devnode_is_registered() and get_device() calls, leading to |
| 164 | * a crash. |
| 165 | */ |
| 166 | mutex_lock(&media_devnode_lock); |
| 167 | mdev = container_of(inode->i_cdev, struct media_devnode, cdev); |
| 168 | /* return ENXIO if the media device has been removed |
| 169 | already or if it is not registered anymore. */ |
| 170 | if (!media_devnode_is_registered(mdev)) { |
| 171 | mutex_unlock(&media_devnode_lock); |
| 172 | return -ENXIO; |
| 173 | } |
| 174 | /* and increase the device refcount */ |
| 175 | get_device(&mdev->dev); |
| 176 | mutex_unlock(&media_devnode_lock); |
| 177 | |
| 178 | filp->private_data = mdev; |
| 179 | |
| 180 | if (mdev->fops->open) { |
| 181 | ret = mdev->fops->open(filp); |
| 182 | if (ret) { |
| 183 | put_device(&mdev->dev); |
Shuah Khan | d40ec6f | 2016-01-27 21:49:33 -0200 | [diff] [blame] | 184 | filp->private_data = NULL; |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 185 | return ret; |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | return 0; |
| 190 | } |
| 191 | |
| 192 | /* Override for the release function */ |
| 193 | static int media_release(struct inode *inode, struct file *filp) |
| 194 | { |
| 195 | struct media_devnode *mdev = media_devnode_data(filp); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 196 | |
| 197 | if (mdev->fops->release) |
| 198 | mdev->fops->release(filp); |
| 199 | |
| 200 | /* decrease the refcount unconditionally since the release() |
| 201 | return value is ignored. */ |
| 202 | put_device(&mdev->dev); |
| 203 | filp->private_data = NULL; |
Mauro Carvalho Chehab | 8b37c64 | 2014-09-03 15:18:27 -0300 | [diff] [blame] | 204 | return 0; |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 205 | } |
| 206 | |
| 207 | static const struct file_operations media_devnode_fops = { |
| 208 | .owner = THIS_MODULE, |
| 209 | .read = media_read, |
| 210 | .write = media_write, |
| 211 | .open = media_open, |
| 212 | .unlocked_ioctl = media_ioctl, |
Sakari Ailus | c6c1d50 | 2013-01-22 12:27:55 -0300 | [diff] [blame] | 213 | #ifdef CONFIG_COMPAT |
| 214 | .compat_ioctl = media_compat_ioctl, |
| 215 | #endif /* CONFIG_COMPAT */ |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 216 | .release = media_release, |
| 217 | .poll = media_poll, |
| 218 | .llseek = no_llseek, |
| 219 | }; |
| 220 | |
Sakari Ailus | 85de721 | 2013-12-12 12:38:17 -0300 | [diff] [blame] | 221 | int __must_check media_devnode_register(struct media_devnode *mdev, |
| 222 | struct module *owner) |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 223 | { |
| 224 | int minor; |
| 225 | int ret; |
| 226 | |
| 227 | /* Part 1: Find a free minor number */ |
| 228 | mutex_lock(&media_devnode_lock); |
Laurent Pinchart | 8c89ddd | 2011-05-30 15:45:47 -0300 | [diff] [blame] | 229 | minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 230 | if (minor == MEDIA_NUM_DEVICES) { |
| 231 | mutex_unlock(&media_devnode_lock); |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 232 | pr_err("could not get a free minor\n"); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 233 | return -ENFILE; |
| 234 | } |
| 235 | |
Laurent Pinchart | 8c89ddd | 2011-05-30 15:45:47 -0300 | [diff] [blame] | 236 | set_bit(minor, media_devnode_nums); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 237 | mutex_unlock(&media_devnode_lock); |
| 238 | |
| 239 | mdev->minor = minor; |
| 240 | |
| 241 | /* Part 2: Initialize and register the character device */ |
| 242 | cdev_init(&mdev->cdev, &media_devnode_fops); |
Sakari Ailus | 85de721 | 2013-12-12 12:38:17 -0300 | [diff] [blame] | 243 | mdev->cdev.owner = owner; |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 244 | |
| 245 | ret = cdev_add(&mdev->cdev, MKDEV(MAJOR(media_dev_t), mdev->minor), 1); |
| 246 | if (ret < 0) { |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 247 | pr_err("%s: cdev_add failed\n", __func__); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 248 | goto error; |
| 249 | } |
| 250 | |
| 251 | /* Part 3: Register the media device */ |
| 252 | mdev->dev.bus = &media_bus_type; |
| 253 | mdev->dev.devt = MKDEV(MAJOR(media_dev_t), mdev->minor); |
| 254 | mdev->dev.release = media_devnode_release; |
| 255 | if (mdev->parent) |
| 256 | mdev->dev.parent = mdev->parent; |
| 257 | dev_set_name(&mdev->dev, "media%d", mdev->minor); |
| 258 | ret = device_register(&mdev->dev); |
| 259 | if (ret < 0) { |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 260 | pr_err("%s: device_register failed\n", __func__); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 261 | goto error; |
| 262 | } |
| 263 | |
| 264 | /* Part 4: Activate this minor. The char device can now be used. */ |
| 265 | set_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); |
| 266 | |
| 267 | return 0; |
| 268 | |
| 269 | error: |
| 270 | cdev_del(&mdev->cdev); |
| 271 | clear_bit(mdev->minor, media_devnode_nums); |
| 272 | return ret; |
| 273 | } |
| 274 | |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 275 | void media_devnode_unregister(struct media_devnode *mdev) |
| 276 | { |
| 277 | /* Check if mdev was ever registered at all */ |
| 278 | if (!media_devnode_is_registered(mdev)) |
| 279 | return; |
| 280 | |
| 281 | mutex_lock(&media_devnode_lock); |
| 282 | clear_bit(MEDIA_FLAG_REGISTERED, &mdev->flags); |
| 283 | mutex_unlock(&media_devnode_lock); |
| 284 | device_unregister(&mdev->dev); |
| 285 | } |
| 286 | |
| 287 | /* |
| 288 | * Initialise media for linux |
| 289 | */ |
| 290 | static int __init media_devnode_init(void) |
| 291 | { |
| 292 | int ret; |
| 293 | |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 294 | pr_info("Linux media interface: v0.10\n"); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 295 | ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES, |
| 296 | MEDIA_NAME); |
| 297 | if (ret < 0) { |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 298 | pr_warn("unable to allocate major\n"); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 299 | return ret; |
| 300 | } |
| 301 | |
| 302 | ret = bus_register(&media_bus_type); |
| 303 | if (ret < 0) { |
| 304 | unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); |
Sachin Kamat | 3c16b2b | 2012-09-24 08:26:24 -0300 | [diff] [blame] | 305 | pr_warn("bus_register failed\n"); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 306 | return -EIO; |
| 307 | } |
| 308 | |
| 309 | return 0; |
| 310 | } |
| 311 | |
| 312 | static void __exit media_devnode_exit(void) |
| 313 | { |
| 314 | bus_unregister(&media_bus_type); |
| 315 | unregister_chrdev_region(media_dev_t, MEDIA_NUM_DEVICES); |
| 316 | } |
| 317 | |
Laurent Pinchart | ff732d2 | 2012-03-12 10:02:47 -0300 | [diff] [blame] | 318 | subsys_initcall(media_devnode_init); |
Laurent Pinchart | cf4b921 | 2009-12-09 08:39:56 -0300 | [diff] [blame] | 319 | module_exit(media_devnode_exit) |
| 320 | |
| 321 | MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>"); |
| 322 | MODULE_DESCRIPTION("Device node registration for media drivers"); |
| 323 | MODULE_LICENSE("GPL"); |