Commit | Line | Data |
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cf4b9211 LP |
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 | ||
3c16b2b3 SK |
33 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
34 | ||
cf4b9211 LP |
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> | |
cf4b9211 LP |
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 | ||
c6c1d50b SA |
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)) | |
cf4b9211 LP |
123 | { |
124 | struct media_devnode *mdev = media_devnode_data(filp); | |
125 | ||
c6c1d50b | 126 | if (!ioctl_func) |
cf4b9211 LP |
127 | return -ENOTTY; |
128 | ||
129 | if (!media_devnode_is_registered(mdev)) | |
130 | return -EIO; | |
131 | ||
c6c1d50b SA |
132 | return ioctl_func(filp, cmd, arg); |
133 | } | |
134 | ||
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); | |
cf4b9211 LP |
140 | } |
141 | ||
c6c1d50b SA |
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 | ||
cf4b9211 LP |
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); | |
d40ec6fd | 184 | filp->private_data = NULL; |
cf4b9211 LP |
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); | |
cf4b9211 LP |
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; | |
8b37c645 | 204 | return 0; |
cf4b9211 LP |
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, | |
c6c1d50b SA |
213 | #ifdef CONFIG_COMPAT |
214 | .compat_ioctl = media_compat_ioctl, | |
215 | #endif /* CONFIG_COMPAT */ | |
cf4b9211 LP |
216 | .release = media_release, |
217 | .poll = media_poll, | |
218 | .llseek = no_llseek, | |
219 | }; | |
220 | ||
85de721c SA |
221 | int __must_check media_devnode_register(struct media_devnode *mdev, |
222 | struct module *owner) | |
cf4b9211 LP |
223 | { |
224 | int minor; | |
225 | int ret; | |
226 | ||
227 | /* Part 1: Find a free minor number */ | |
228 | mutex_lock(&media_devnode_lock); | |
8c89ddd5 | 229 | minor = find_next_zero_bit(media_devnode_nums, MEDIA_NUM_DEVICES, 0); |
cf4b9211 LP |
230 | if (minor == MEDIA_NUM_DEVICES) { |
231 | mutex_unlock(&media_devnode_lock); | |
3c16b2b3 | 232 | pr_err("could not get a free minor\n"); |
cf4b9211 LP |
233 | return -ENFILE; |
234 | } | |
235 | ||
8c89ddd5 | 236 | set_bit(minor, media_devnode_nums); |
cf4b9211 LP |
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); | |
85de721c | 243 | mdev->cdev.owner = owner; |
cf4b9211 LP |
244 | |
245 | ret = cdev_add(&mdev->cdev, MKDEV(MAJOR(media_dev_t), mdev->minor), 1); | |
246 | if (ret < 0) { | |
3c16b2b3 | 247 | pr_err("%s: cdev_add failed\n", __func__); |
cf4b9211 LP |
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) { | |
3c16b2b3 | 260 | pr_err("%s: device_register failed\n", __func__); |
cf4b9211 LP |
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 | ||
cf4b9211 LP |
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 | ||
3c16b2b3 | 294 | pr_info("Linux media interface: v0.10\n"); |
cf4b9211 LP |
295 | ret = alloc_chrdev_region(&media_dev_t, 0, MEDIA_NUM_DEVICES, |
296 | MEDIA_NAME); | |
297 | if (ret < 0) { | |
3c16b2b3 | 298 | pr_warn("unable to allocate major\n"); |
cf4b9211 LP |
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); | |
3c16b2b3 | 305 | pr_warn("bus_register failed\n"); |
cf4b9211 LP |
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 | ||
ff732d28 | 318 | subsys_initcall(media_devnode_init); |
cf4b9211 LP |
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"); |