1/*
  2 * V4L2 asynchronous subdevice registration API
  3 *
  4 * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10
 11#include <linux/device.h>
 12#include <linux/err.h>
 13#include <linux/i2c.h>
 14#include <linux/list.h>
 15#include <linux/module.h>
 16#include <linux/mutex.h>
 17#include <linux/platform_device.h>
 18#include <linux/slab.h>
 19#include <linux/types.h>
 20
 21#include <media/v4l2-async.h>
 22#include <media/v4l2-device.h>
 23#include <media/v4l2-subdev.h>
 24
 25static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 26{
 27#if IS_ENABLED(CONFIG_I2C)
 28	struct i2c_client *client = i2c_verify_client(sd->dev);
 29	return client &&
 30		asd->match.i2c.adapter_id == client->adapter->nr &&
 31		asd->match.i2c.address == client->addr;
 32#else
 33	return false;
 34#endif
 35}
 36
 37static bool match_devname(struct v4l2_subdev *sd,
 38			  struct v4l2_async_subdev *asd)
 39{
 40	return !strcmp(asd->match.device_name.name, dev_name(sd->dev));
 41}
 42
 43static bool match_of(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 44{
 45	return sd->of_node == asd->match.of.node;
 46}
 47
 48static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 49{
 50	if (!asd->match.custom.match)
 51		/* Match always */
 52		return true;
 53
 54	return asd->match.custom.match(sd->dev, asd);
 55}
 56
 57static LIST_HEAD(subdev_list);
 58static LIST_HEAD(notifier_list);
 59static DEFINE_MUTEX(list_lock);
 60
 61static struct v4l2_async_subdev *v4l2_async_belongs(struct v4l2_async_notifier *notifier,
 62						    struct v4l2_subdev *sd)
 63{
 64	bool (*match)(struct v4l2_subdev *, struct v4l2_async_subdev *);
 65	struct v4l2_async_subdev *asd;
 66
 67	list_for_each_entry(asd, &notifier->waiting, list) {
 68		/* bus_type has been verified valid before */
 69		switch (asd->match_type) {
 70		case V4L2_ASYNC_MATCH_CUSTOM:
 71			match = match_custom;
 72			break;
 73		case V4L2_ASYNC_MATCH_DEVNAME:
 74			match = match_devname;
 75			break;
 76		case V4L2_ASYNC_MATCH_I2C:
 77			match = match_i2c;
 78			break;
 79		case V4L2_ASYNC_MATCH_OF:
 80			match = match_of;
 81			break;
 82		default:
 83			/* Cannot happen, unless someone breaks us */
 84			WARN_ON(true);
 85			return NULL;
 86		}
 87
 88		/* match cannot be NULL here */
 89		if (match(sd, asd))
 90			return asd;
 91	}
 92
 93	return NULL;
 94}
 95
 96static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
 97				  struct v4l2_subdev *sd,
 98				  struct v4l2_async_subdev *asd)
 99{
100	int ret;
101
102	/* Remove from the waiting list */
103	list_del(&asd->list);
104	sd->asd = asd;
105	sd->notifier = notifier;
106
107	if (notifier->bound) {
108		ret = notifier->bound(notifier, sd, asd);
109		if (ret < 0)
110			return ret;
111	}
112	/* Move from the global subdevice list to notifier's done */
113	list_move(&sd->async_list, &notifier->done);
114
115	ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
116	if (ret < 0) {
117		if (notifier->unbind)
118			notifier->unbind(notifier, sd, asd);
119		return ret;
120	}
121
122	ret = v4l2_subdev_call(sd, core, registered_async);
123	if (ret < 0 && ret != -ENOIOCTLCMD) {
124		if (notifier->unbind)
125			notifier->unbind(notifier, sd, asd);
126		return ret;
127	}
128
129	if (list_empty(&notifier->waiting) && notifier->complete)
130		return notifier->complete(notifier);
131
132	return 0;
133}
134
135static void v4l2_async_cleanup(struct v4l2_subdev *sd)
136{
137	v4l2_device_unregister_subdev(sd);
138	/* Subdevice driver will reprobe and put the subdev back onto the list */
139	list_del_init(&sd->async_list);
140	sd->asd = NULL;
141	sd->dev = NULL;
142}
143
144int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
145				 struct v4l2_async_notifier *notifier)
146{
147	struct v4l2_subdev *sd, *tmp;
148	struct v4l2_async_subdev *asd;
149	int i;
150
151	if (!notifier->num_subdevs || notifier->num_subdevs > V4L2_MAX_SUBDEVS)
152		return -EINVAL;
153
154	notifier->v4l2_dev = v4l2_dev;
155	INIT_LIST_HEAD(&notifier->waiting);
156	INIT_LIST_HEAD(&notifier->done);
157
158	for (i = 0; i < notifier->num_subdevs; i++) {
159		asd = notifier->subdevs[i];
160
161		switch (asd->match_type) {
162		case V4L2_ASYNC_MATCH_CUSTOM:
163		case V4L2_ASYNC_MATCH_DEVNAME:
164		case V4L2_ASYNC_MATCH_I2C:
165		case V4L2_ASYNC_MATCH_OF:
166			break;
167		default:
168			dev_err(notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL,
169				"Invalid match type %u on %p\n",
170				asd->match_type, asd);
171			return -EINVAL;
172		}
173		list_add_tail(&asd->list, &notifier->waiting);
174	}
175
176	mutex_lock(&list_lock);
177
178	/* Keep also completed notifiers on the list */
179	list_add(&notifier->list, &notifier_list);
180
181	list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
182		int ret;
183
184		asd = v4l2_async_belongs(notifier, sd);
185		if (!asd)
186			continue;
187
188		ret = v4l2_async_test_notify(notifier, sd, asd);
189		if (ret < 0) {
190			mutex_unlock(&list_lock);
191			return ret;
192		}
193	}
194
195	mutex_unlock(&list_lock);
196
197	return 0;
198}
199EXPORT_SYMBOL(v4l2_async_notifier_register);
200
201void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
202{
203	struct v4l2_subdev *sd, *tmp;
204	unsigned int notif_n_subdev = notifier->num_subdevs;
205	unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
206	struct device **dev;
207	int i = 0;
208
209	if (!notifier->v4l2_dev)
210		return;
211
212	dev = kmalloc(n_subdev * sizeof(*dev), GFP_KERNEL);
213	if (!dev) {
214		dev_err(notifier->v4l2_dev->dev,
215			"Failed to allocate device cache!\n");
216	}
217
218	mutex_lock(&list_lock);
219
220	list_del(&notifier->list);
221
222	list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
223		struct device *d;
224
225		d = get_device(sd->dev);
226
227		v4l2_async_cleanup(sd);
228
229		/* If we handled USB devices, we'd have to lock the parent too */
230		device_release_driver(d);
231
232		if (notifier->unbind)
233			notifier->unbind(notifier, sd, sd->asd);
234
235		/*
236		 * Store device at the device cache, in order to call
237		 * put_device() on the final step
238		 */
239		if (dev)
240			dev[i++] = d;
241		else
242			put_device(d);
243	}
244
245	mutex_unlock(&list_lock);
246
247	/*
248	 * Call device_attach() to reprobe devices
249	 *
250	 * NOTE: If dev allocation fails, i is 0, and the whole loop won't be
251	 * executed.
252	 */
253	while (i--) {
254		struct device *d = dev[i];
255
256		if (d && device_attach(d) < 0) {
257			const char *name = "(none)";
258			int lock = device_trylock(d);
259
260			if (lock && d->driver)
261				name = d->driver->name;
262			dev_err(d, "Failed to re-probe to %s\n", name);
263			if (lock)
264				device_unlock(d);
265		}
266		put_device(d);
267	}
268	kfree(dev);
269
270	notifier->v4l2_dev = NULL;
271
272	/*
273	 * Don't care about the waiting list, it is initialised and populated
274	 * upon notifier registration.
275	 */
276}
277EXPORT_SYMBOL(v4l2_async_notifier_unregister);
278
279int v4l2_async_register_subdev(struct v4l2_subdev *sd)
280{
281	struct v4l2_async_notifier *notifier;
282
283	/*
284	 * No reference taken. The reference is held by the device
285	 * (struct v4l2_subdev.dev), and async sub-device does not
286	 * exist independently of the device at any point of time.
287	 */
288	if (!sd->of_node && sd->dev)
289		sd->of_node = sd->dev->of_node;
290
291	mutex_lock(&list_lock);
292
293	INIT_LIST_HEAD(&sd->async_list);
294
295	list_for_each_entry(notifier, &notifier_list, list) {
296		struct v4l2_async_subdev *asd = v4l2_async_belongs(notifier, sd);
297		if (asd) {
298			int ret = v4l2_async_test_notify(notifier, sd, asd);
299			mutex_unlock(&list_lock);
300			return ret;
301		}
302	}
303
304	/* None matched, wait for hot-plugging */
305	list_add(&sd->async_list, &subdev_list);
306
307	mutex_unlock(&list_lock);
308
309	return 0;
310}
311EXPORT_SYMBOL(v4l2_async_register_subdev);
312
313void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
314{
315	struct v4l2_async_notifier *notifier = sd->notifier;
316
317	if (!sd->asd) {
318		if (!list_empty(&sd->async_list))
319			v4l2_async_cleanup(sd);
320		return;
321	}
322
323	mutex_lock(&list_lock);
324
325	list_add(&sd->asd->list, &notifier->waiting);
326
327	v4l2_async_cleanup(sd);
328
329	if (notifier->unbind)
330		notifier->unbind(notifier, sd, sd->asd);
331
332	mutex_unlock(&list_lock);
333}
334EXPORT_SYMBOL(v4l2_async_unregister_subdev);