1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3     V4L2 device support.
4 
5     Copyright (C) 2008  Hans Verkuil <hverkuil@xs4all.nl>
6 
7  */
8 
9 #include <linux/types.h>
10 #include <linux/ioctl.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/videodev2.h>
14 #include <media/v4l2-device.h>
15 #include <media/v4l2-ctrls.h>
16 
17 int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
18 {
19 	if (v4l2_dev == NULL)
20 		return -EINVAL;
21 
22 	INIT_LIST_HEAD(&v4l2_dev->subdevs);
23 	spin_lock_init(&v4l2_dev->lock);
24 	v4l2_prio_init(&v4l2_dev->prio);
25 	kref_init(&v4l2_dev->ref);
26 	get_device(dev);
27 	v4l2_dev->dev = dev;
28 	if (dev == NULL) {
29 		/* If dev == NULL, then name must be filled in by the caller */
30 		if (WARN_ON(!v4l2_dev->name[0]))
31 			return -EINVAL;
32 		return 0;
33 	}
34 
35 	/* Set name to driver name + device name if it is empty. */
36 	if (!v4l2_dev->name[0])
37 		snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
38 			dev->driver->name, dev_name(dev));
39 	if (!dev_get_drvdata(dev))
40 		dev_set_drvdata(dev, v4l2_dev);
41 	return 0;
42 }
43 EXPORT_SYMBOL_GPL(v4l2_device_register);
44 
45 static void v4l2_device_release(struct kref *ref)
46 {
47 	struct v4l2_device *v4l2_dev =
48 		container_of(ref, struct v4l2_device, ref);
49 
50 	if (v4l2_dev->release)
51 		v4l2_dev->release(v4l2_dev);
52 }
53 
54 int v4l2_device_put(struct v4l2_device *v4l2_dev)
55 {
56 	return kref_put(&v4l2_dev->ref, v4l2_device_release);
57 }
58 EXPORT_SYMBOL_GPL(v4l2_device_put);
59 
60 int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
61 						atomic_t *instance)
62 {
63 	int num = atomic_inc_return(instance) - 1;
64 	int len = strlen(basename);
65 
66 	if (basename[len - 1] >= '0' && basename[len - 1] <= '9')
67 		snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
68 				"%s-%d", basename, num);
69 	else
70 		snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
71 				"%s%d", basename, num);
72 	return num;
73 }
74 EXPORT_SYMBOL_GPL(v4l2_device_set_name);
75 
76 void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
77 {
78 	if (v4l2_dev->dev == NULL)
79 		return;
80 
81 	if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev)
82 		dev_set_drvdata(v4l2_dev->dev, NULL);
83 	put_device(v4l2_dev->dev);
84 	v4l2_dev->dev = NULL;
85 }
86 EXPORT_SYMBOL_GPL(v4l2_device_disconnect);
87 
88 void v4l2_device_unregister(struct v4l2_device *v4l2_dev)
89 {
90 	struct v4l2_subdev *sd, *next;
91 
92 	/* Just return if v4l2_dev is NULL or if it was already
93 	 * unregistered before. */
94 	if (v4l2_dev == NULL || !v4l2_dev->name[0])
95 		return;
96 	v4l2_device_disconnect(v4l2_dev);
97 
98 	/* Unregister subdevs */
99 	list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
100 		v4l2_device_unregister_subdev(sd);
101 		if (sd->flags & V4L2_SUBDEV_FL_IS_I2C)
102 			v4l2_i2c_subdev_unregister(sd);
103 		else if (sd->flags & V4L2_SUBDEV_FL_IS_SPI)
104 			v4l2_spi_subdev_unregister(sd);
105 	}
106 	/* Mark as unregistered, thus preventing duplicate unregistrations */
107 	v4l2_dev->name[0] = '\0';
108 }
109 EXPORT_SYMBOL_GPL(v4l2_device_unregister);
110 
111 int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
112 				struct v4l2_subdev *sd)
113 {
114 	int err;
115 
116 	/* Check for valid input */
117 	if (!v4l2_dev || !sd || sd->v4l2_dev || !sd->name[0])
118 		return -EINVAL;
119 
120 	/*
121 	 * The reason to acquire the module here is to avoid unloading
122 	 * a module of sub-device which is registered to a media
123 	 * device. To make it possible to unload modules for media
124 	 * devices that also register sub-devices, do not
125 	 * try_module_get() such sub-device owners.
126 	 */
127 	sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
128 		sd->owner == v4l2_dev->dev->driver->owner;
129 
130 	if (!sd->owner_v4l2_dev && !try_module_get(sd->owner))
131 		return -ENODEV;
132 
133 	sd->v4l2_dev = v4l2_dev;
134 	/* This just returns 0 if either of the two args is NULL */
135 	err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler,
136 				    NULL, true);
137 	if (err)
138 		goto error_module;
139 
140 #if defined(CONFIG_MEDIA_CONTROLLER)
141 	/* Register the entity. */
142 	if (v4l2_dev->mdev) {
143 		err = media_device_register_entity(v4l2_dev->mdev, &sd->entity);
144 		if (err < 0)
145 			goto error_module;
146 	}
147 #endif
148 
149 	if (sd->internal_ops && sd->internal_ops->registered) {
150 		err = sd->internal_ops->registered(sd);
151 		if (err)
152 			goto error_unregister;
153 	}
154 
155 	spin_lock(&v4l2_dev->lock);
156 	list_add_tail(&sd->list, &v4l2_dev->subdevs);
157 	spin_unlock(&v4l2_dev->lock);
158 
159 	return 0;
160 
161 error_unregister:
162 #if defined(CONFIG_MEDIA_CONTROLLER)
163 	media_device_unregister_entity(&sd->entity);
164 #endif
165 error_module:
166 	if (!sd->owner_v4l2_dev)
167 		module_put(sd->owner);
168 	sd->v4l2_dev = NULL;
169 	return err;
170 }
171 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
172 
173 static void v4l2_subdev_release(struct v4l2_subdev *sd)
174 {
175 	struct module *owner = !sd->owner_v4l2_dev ? sd->owner : NULL;
176 
177 	if (sd->internal_ops && sd->internal_ops->release)
178 		sd->internal_ops->release(sd);
179 	sd->devnode = NULL;
180 	module_put(owner);
181 }
182 
183 static void v4l2_device_release_subdev_node(struct video_device *vdev)
184 {
185 	v4l2_subdev_release(video_get_drvdata(vdev));
186 	kfree(vdev);
187 }
188 
189 int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
190 					bool read_only)
191 {
192 	struct video_device *vdev;
193 	struct v4l2_subdev *sd;
194 	int err;
195 
196 	/* Register a device node for every subdev marked with the
197 	 * V4L2_SUBDEV_FL_HAS_DEVNODE flag.
198 	 */
199 	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
200 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
201 			continue;
202 
203 		if (sd->devnode)
204 			continue;
205 
206 		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
207 		if (!vdev) {
208 			err = -ENOMEM;
209 			goto clean_up;
210 		}
211 
212 		video_set_drvdata(vdev, sd);
213 		strscpy(vdev->name, sd->name, sizeof(vdev->name));
214 		vdev->dev_parent = sd->dev;
215 		vdev->v4l2_dev = v4l2_dev;
216 		vdev->fops = &v4l2_subdev_fops;
217 		vdev->release = v4l2_device_release_subdev_node;
218 		vdev->ctrl_handler = sd->ctrl_handler;
219 		if (read_only)
220 			set_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags);
221 		sd->devnode = vdev;
222 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
223 					      sd->owner);
224 		if (err < 0) {
225 			sd->devnode = NULL;
226 			kfree(vdev);
227 			goto clean_up;
228 		}
229 #if defined(CONFIG_MEDIA_CONTROLLER)
230 		sd->entity.info.dev.major = VIDEO_MAJOR;
231 		sd->entity.info.dev.minor = vdev->minor;
232 
233 		/* Interface is created by __video_register_device() */
234 		if (vdev->v4l2_dev->mdev) {
235 			struct media_link *link;
236 
237 			link = media_create_intf_link(&sd->entity,
238 						      &vdev->intf_devnode->intf,
239 						      MEDIA_LNK_FL_ENABLED |
240 						      MEDIA_LNK_FL_IMMUTABLE);
241 			if (!link) {
242 				err = -ENOMEM;
243 				goto clean_up;
244 			}
245 		}
246 #endif
247 	}
248 	return 0;
249 
250 clean_up:
251 	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
252 		if (!sd->devnode)
253 			break;
254 		video_unregister_device(sd->devnode);
255 	}
256 
257 	return err;
258 }
259 EXPORT_SYMBOL_GPL(__v4l2_device_register_subdev_nodes);
260 
261 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
262 {
263 	struct v4l2_device *v4l2_dev;
264 
265 	/* return if it isn't registered */
266 	if (sd == NULL || sd->v4l2_dev == NULL)
267 		return;
268 
269 	v4l2_dev = sd->v4l2_dev;
270 
271 	spin_lock(&v4l2_dev->lock);
272 	list_del(&sd->list);
273 	spin_unlock(&v4l2_dev->lock);
274 
275 	if (sd->internal_ops && sd->internal_ops->unregistered)
276 		sd->internal_ops->unregistered(sd);
277 	sd->v4l2_dev = NULL;
278 
279 #if defined(CONFIG_MEDIA_CONTROLLER)
280 	if (v4l2_dev->mdev) {
281 		/*
282 		 * No need to explicitly remove links, as both pads and
283 		 * links are removed by the function below, in the right order
284 		 */
285 		media_device_unregister_entity(&sd->entity);
286 	}
287 #endif
288 	if (sd->devnode)
289 		video_unregister_device(sd->devnode);
290 	else
291 		v4l2_subdev_release(sd);
292 }
293 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
294