drivers/media/v4l2-core/v4l2-async.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * V4L2 asynchronous subdevice registration API
  *
  * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/types.h>

 #include <media/v4l2-async.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-subdev.h>

 static int v4l2_async_notifier_call_bound(struct v4l2_async_notifier *n,
 					  struct v4l2_subdev *subdev,
 					  struct v4l2_async_subdev *asd)
 {
 	if (!n->ops || !n->ops->bound)
 		return 0;

 	return n->ops->bound(n, subdev, asd);
 }

 static void v4l2_async_notifier_call_unbind(struct v4l2_async_notifier *n,
 					    struct v4l2_subdev *subdev,
 					    struct v4l2_async_subdev *asd)
 {
 	if (!n->ops || !n->ops->unbind)
 		return;

 	n->ops->unbind(n, subdev, asd);
 }

 static int v4l2_async_notifier_call_complete(struct v4l2_async_notifier *n)
 {
 	if (!n->ops || !n->ops->complete)
 		return 0;

 	return n->ops->complete(n);
 }

 static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 {
 #if IS_ENABLED(CONFIG_I2C)
 	struct i2c_client *client = i2c_verify_client(sd->dev);

 	return client &&
 		asd->match.i2c.adapter_id == client->adapter->nr &&
 		asd->match.i2c.address == client->addr;
 #else
 	return false;
 #endif
 }

 static bool match_devname(struct v4l2_subdev *sd,
 			  struct v4l2_async_subdev *asd)
 {
 	return !strcmp(asd->match.device_name, dev_name(sd->dev));
 }

 static bool match_fwnode(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 {
 	return sd->fwnode == asd->match.fwnode;
 }

 static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 {
 	if (!asd->match.custom.match)
 		/* Match always */
 		return true;

 	return asd->match.custom.match(sd->dev, asd);
 }

 static LIST_HEAD(subdev_list);
 static LIST_HEAD(notifier_list);
 static DEFINE_MUTEX(list_lock);

 static struct v4l2_async_subdev *
 v4l2_async_find_match(struct v4l2_async_notifier *notifier,
 		      struct v4l2_subdev *sd)
 {
 	bool (*match)(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd);
 	struct v4l2_async_subdev *asd;

 	list_for_each_entry(asd, &notifier->waiting, list) {
 		/* bus_type has been verified valid before */
 		switch (asd->match_type) {
 		case V4L2_ASYNC_MATCH_CUSTOM:
 			match = match_custom;
 			break;
 		case V4L2_ASYNC_MATCH_DEVNAME:
 			match = match_devname;
 			break;
 		case V4L2_ASYNC_MATCH_I2C:
 			match = match_i2c;
 			break;
 		case V4L2_ASYNC_MATCH_FWNODE:
 			match = match_fwnode;
 			break;
 		default:
 			/* Cannot happen, unless someone breaks us */
 			WARN_ON(true);
 			return NULL;
 		}

 		/* match cannot be NULL here */
 		if (match(sd, asd))
 			return asd;
 	}

 	return NULL;
 }

 /* Compare two async sub-device descriptors for equivalence */
 static bool asd_equal(struct v4l2_async_subdev *asd_x,
 		      struct v4l2_async_subdev *asd_y)
 {
 	if (asd_x->match_type != asd_y->match_type)
 		return false;

 	switch (asd_x->match_type) {
 	case V4L2_ASYNC_MATCH_DEVNAME:
 		return strcmp(asd_x->match.device_name,
 			      asd_y->match.device_name) == 0;
 	case V4L2_ASYNC_MATCH_I2C:
 		return asd_x->match.i2c.adapter_id ==
 			asd_y->match.i2c.adapter_id &&
 			asd_x->match.i2c.address ==
 			asd_y->match.i2c.address;
 	case V4L2_ASYNC_MATCH_FWNODE:
 		return asd_x->match.fwnode == asd_y->match.fwnode;
 	default:
 		break;
 	}

 	return false;
 }

 /* Find the sub-device notifier registered by a sub-device driver. */
 static struct v4l2_async_notifier *
 v4l2_async_find_subdev_notifier(struct v4l2_subdev *sd)
 {
 	struct v4l2_async_notifier *n;

 	list_for_each_entry(n, &notifier_list, list)
 		if (n->sd == sd)
 			return n;

 	return NULL;
 }

 /* Get v4l2_device related to the notifier if one can be found. */
 static struct v4l2_device *
 v4l2_async_notifier_find_v4l2_dev(struct v4l2_async_notifier *notifier)
 {
 	while (notifier->parent)
 		notifier = notifier->parent;

 	return notifier->v4l2_dev;
 }

 /*
  * Return true if all child sub-device notifiers are complete, false otherwise.
  */
 static bool
 v4l2_async_notifier_can_complete(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_subdev *sd;

 	if (!list_empty(&notifier->waiting))
 		return false;

 	list_for_each_entry(sd, &notifier->done, async_list) {
 		struct v4l2_async_notifier *subdev_notifier =
 			v4l2_async_find_subdev_notifier(sd);

 		if (subdev_notifier &&
 		    !v4l2_async_notifier_can_complete(subdev_notifier))
 			return false;
 	}

 	return true;
 }

 /*
  * Complete the master notifier if possible. This is done when all async
  * sub-devices have been bound; v4l2_device is also available then.
  */
 static int
 v4l2_async_notifier_try_complete(struct v4l2_async_notifier *notifier)
 {
 	/* Quick check whether there are still more sub-devices here. */
 	if (!list_empty(&notifier->waiting))
 		return 0;

 	/* Check the entire notifier tree; find the root notifier first. */
 	while (notifier->parent)
 		notifier = notifier->parent;

 	/* This is root if it has v4l2_dev. */
 	if (!notifier->v4l2_dev)
 		return 0;

 	/* Is everything ready? */
 	if (!v4l2_async_notifier_can_complete(notifier))
 		return 0;

 	return v4l2_async_notifier_call_complete(notifier);
 }

 static int
 v4l2_async_notifier_try_all_subdevs(struct v4l2_async_notifier *notifier);

 static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
 				   struct v4l2_device *v4l2_dev,
 				   struct v4l2_subdev *sd,
 				   struct v4l2_async_subdev *asd)
 {
 	struct v4l2_async_notifier *subdev_notifier;
 	int ret;

 	ret = v4l2_device_register_subdev(v4l2_dev, sd);
 	if (ret < 0)
 		return ret;

 	ret = v4l2_async_notifier_call_bound(notifier, sd, asd);
 	if (ret < 0) {
 		v4l2_device_unregister_subdev(sd);
 		return ret;
 	}

 	/* Remove from the waiting list */
 	list_del(&asd->list);
 	sd->asd = asd;
 	sd->notifier = notifier;

 	/* Move from the global subdevice list to notifier's done */
 	list_move(&sd->async_list, &notifier->done);

 	/*
 	 * See if the sub-device has a notifier. If not, return here.
 	 */
 	subdev_notifier = v4l2_async_find_subdev_notifier(sd);
 	if (!subdev_notifier || subdev_notifier->parent)
 		return 0;

 	/*
 	 * Proceed with checking for the sub-device notifier's async
 	 * sub-devices, and return the result. The error will be handled by the
 	 * caller.
 	 */
 	subdev_notifier->parent = notifier;

 	return v4l2_async_notifier_try_all_subdevs(subdev_notifier);
 }

 /* Test all async sub-devices in a notifier for a match. */
 static int
 v4l2_async_notifier_try_all_subdevs(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_device *v4l2_dev =
 		v4l2_async_notifier_find_v4l2_dev(notifier);
 	struct v4l2_subdev *sd;

 	if (!v4l2_dev)
 		return 0;

 again:
 	list_for_each_entry(sd, &subdev_list, async_list) {
 		struct v4l2_async_subdev *asd;
 		int ret;

 		asd = v4l2_async_find_match(notifier, sd);
 		if (!asd)
 			continue;

 		ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
 		if (ret < 0)
 			return ret;

 		/*
 		 * v4l2_async_match_notify() may lead to registering a
 		 * new notifier and thus changing the async subdevs
 		 * list. In order to proceed safely from here, restart
 		 * parsing the list from the beginning.
 		 */
 		goto again;
 	}

 	return 0;
 }

 static void v4l2_async_cleanup(struct v4l2_subdev *sd)
 {
 	v4l2_device_unregister_subdev(sd);
 	/*
 	 * Subdevice driver will reprobe and put the subdev back
 	 * onto the list
 	 */
 	list_del_init(&sd->async_list);
 	sd->asd = NULL;
 }

 /* Unbind all sub-devices in the notifier tree. */
 static void
 v4l2_async_notifier_unbind_all_subdevs(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_subdev *sd, *tmp;

 	list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
 		struct v4l2_async_notifier *subdev_notifier =
 			v4l2_async_find_subdev_notifier(sd);

 		if (subdev_notifier)
 			v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);

 		v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
 		v4l2_async_cleanup(sd);

 		list_move(&sd->async_list, &subdev_list);
 	}

 	notifier->parent = NULL;
 }

 /* See if an async sub-device can be found in a notifier's lists. */
 static bool
 __v4l2_async_notifier_has_async_subdev(struct v4l2_async_notifier *notifier,
 				       struct v4l2_async_subdev *asd)
 {
 	struct v4l2_async_subdev *asd_y;
 	struct v4l2_subdev *sd;

 	list_for_each_entry(asd_y, &notifier->waiting, list)
 		if (asd_equal(asd, asd_y))
 			return true;

 	list_for_each_entry(sd, &notifier->done, async_list) {
 		if (WARN_ON(!sd->asd))
 			continue;

 		if (asd_equal(asd, sd->asd))
 			return true;
 	}

 	return false;
 }

 /*
  * Find out whether an async sub-device was set up already or
  * whether it exists in a given notifier before @this_index.
  * If @this_index < 0, search the notifier's entire @asd_list.
  */
 static bool
 v4l2_async_notifier_has_async_subdev(struct v4l2_async_notifier *notifier,
 				     struct v4l2_async_subdev *asd,
 				     int this_index)
 {
 	struct v4l2_async_subdev *asd_y;
 	int j = 0;

 	lockdep_assert_held(&list_lock);

 	/* Check that an asd is not being added more than once. */
 	list_for_each_entry(asd_y, &notifier->asd_list, asd_list) {
 		if (this_index >= 0 && j++ >= this_index)
 			break;
 		if (asd_equal(asd, asd_y))
 			return true;
 	}

 	/* Check that an asd does not exist in other notifiers. */
 	list_for_each_entry(notifier, &notifier_list, list)
 		if (__v4l2_async_notifier_has_async_subdev(notifier, asd))
 			return true;

 	return false;
 }

 static int v4l2_async_notifier_asd_valid(struct v4l2_async_notifier *notifier,
 					 struct v4l2_async_subdev *asd,
 					 int this_index)
 {
 	struct device *dev =
 		notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL;

 	if (!asd)
 		return -EINVAL;

 	switch (asd->match_type) {
 	case V4L2_ASYNC_MATCH_CUSTOM:
 	case V4L2_ASYNC_MATCH_DEVNAME:
 	case V4L2_ASYNC_MATCH_I2C:
 	case V4L2_ASYNC_MATCH_FWNODE:
 		if (v4l2_async_notifier_has_async_subdev(notifier, asd,
 							 this_index)) {
 			dev_dbg(dev, "subdev descriptor already listed in this or other notifiers\n");
 			return -EEXIST;
 		}
 		break;
 	default:
 		dev_err(dev, "Invalid match type %u on %p\n",
 			asd->match_type, asd);
 		return -EINVAL;
 	}

 	return 0;
 }

 void v4l2_async_notifier_init(struct v4l2_async_notifier *notifier)
 {
 	INIT_LIST_HEAD(&notifier->asd_list);
 }
 EXPORT_SYMBOL(v4l2_async_notifier_init);

 static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_async_subdev *asd;
 	int ret, i = 0;

 	INIT_LIST_HEAD(&notifier->waiting);
 	INIT_LIST_HEAD(&notifier->done);

 	mutex_lock(&list_lock);

 	list_for_each_entry(asd, &notifier->asd_list, asd_list) {
 		ret = v4l2_async_notifier_asd_valid(notifier, asd, i++);
 		if (ret)
 			goto err_unlock;

 		list_add_tail(&asd->list, &notifier->waiting);
 	}

 	ret = v4l2_async_notifier_try_all_subdevs(notifier);
 	if (ret < 0)
 		goto err_unbind;

 	ret = v4l2_async_notifier_try_complete(notifier);
 	if (ret < 0)
 		goto err_unbind;

 	/* Keep also completed notifiers on the list */
 	list_add(&notifier->list, &notifier_list);

 	mutex_unlock(&list_lock);

 	return 0;

 err_unbind:
 	/*
 	 * On failure, unbind all sub-devices registered through this notifier.
 	 */
 	v4l2_async_notifier_unbind_all_subdevs(notifier);

 err_unlock:
 	mutex_unlock(&list_lock);

 	return ret;
 }

 int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
 				 struct v4l2_async_notifier *notifier)
 {
 	int ret;

 	if (WARN_ON(!v4l2_dev || notifier->sd))
 		return -EINVAL;

 	notifier->v4l2_dev = v4l2_dev;

 	ret = __v4l2_async_notifier_register(notifier);
 	if (ret)
 		notifier->v4l2_dev = NULL;

 	return ret;
 }
 EXPORT_SYMBOL(v4l2_async_notifier_register);

 int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
 					struct v4l2_async_notifier *notifier)
 {
 	int ret;

 	if (WARN_ON(!sd || notifier->v4l2_dev))
 		return -EINVAL;

 	notifier->sd = sd;

 	ret = __v4l2_async_notifier_register(notifier);
 	if (ret)
 		notifier->sd = NULL;

 	return ret;
 }
 EXPORT_SYMBOL(v4l2_async_subdev_notifier_register);

 static void
 __v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
 {
 	if (!notifier || (!notifier->v4l2_dev && !notifier->sd))
 		return;

 	v4l2_async_notifier_unbind_all_subdevs(notifier);

 	notifier->sd = NULL;
 	notifier->v4l2_dev = NULL;

 	list_del(&notifier->list);
 }

 void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
 {
 	mutex_lock(&list_lock);

 	__v4l2_async_notifier_unregister(notifier);

 	mutex_unlock(&list_lock);
 }
 EXPORT_SYMBOL(v4l2_async_notifier_unregister);

 static void __v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_async_subdev *asd, *tmp;

 	if (!notifier || !notifier->asd_list.next)
 		return;

 	list_for_each_entry_safe(asd, tmp, &notifier->asd_list, asd_list) {
 		switch (asd->match_type) {
 		case V4L2_ASYNC_MATCH_FWNODE:
 			fwnode_handle_put(asd->match.fwnode);
 			break;
 		default:
 			break;
 		}

 		list_del(&asd->asd_list);
 		kfree(asd);
 	}
 }

 void v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier)
 {
 	mutex_lock(&list_lock);

 	__v4l2_async_notifier_cleanup(notifier);

 	mutex_unlock(&list_lock);
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_cleanup);

 int v4l2_async_notifier_add_subdev(struct v4l2_async_notifier *notifier,
 				   struct v4l2_async_subdev *asd)
 {
 	int ret;

 	mutex_lock(&list_lock);

 	ret = v4l2_async_notifier_asd_valid(notifier, asd, -1);
 	if (ret)
 		goto unlock;

 	list_add_tail(&asd->asd_list, &notifier->asd_list);

 unlock:
 	mutex_unlock(&list_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_subdev);

 struct v4l2_async_subdev *
 v4l2_async_notifier_add_fwnode_subdev(struct v4l2_async_notifier *notifier,
 				      struct fwnode_handle *fwnode,
 				      unsigned int asd_struct_size)
 {
 	struct v4l2_async_subdev *asd;
 	int ret;

 	asd = kzalloc(asd_struct_size, GFP_KERNEL);
 	if (!asd)
 		return ERR_PTR(-ENOMEM);

 	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
 	asd->match.fwnode = fwnode_handle_get(fwnode);

 	ret = v4l2_async_notifier_add_subdev(notifier, asd);
 	if (ret) {
 		fwnode_handle_put(fwnode);
 		kfree(asd);
 		return ERR_PTR(ret);
 	}

 	return asd;
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_fwnode_subdev);

 int
 v4l2_async_notifier_add_fwnode_remote_subdev(struct v4l2_async_notifier *notif,
 					     struct fwnode_handle *endpoint,
 					     struct v4l2_async_subdev *asd)
 {
 	struct fwnode_handle *remote;
 	int ret;

 	remote = fwnode_graph_get_remote_port_parent(endpoint);
 	if (!remote)
 		return -ENOTCONN;

 	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
 	asd->match.fwnode = remote;

 	ret = v4l2_async_notifier_add_subdev(notif, asd);
 	if (ret)
 		fwnode_handle_put(remote);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_fwnode_remote_subdev);

 struct v4l2_async_subdev *
 v4l2_async_notifier_add_i2c_subdev(struct v4l2_async_notifier *notifier,
 				   int adapter_id, unsigned short address,
 				   unsigned int asd_struct_size)
 {
 	struct v4l2_async_subdev *asd;
 	int ret;

 	asd = kzalloc(asd_struct_size, GFP_KERNEL);
 	if (!asd)
 		return ERR_PTR(-ENOMEM);

 	asd->match_type = V4L2_ASYNC_MATCH_I2C;
 	asd->match.i2c.adapter_id = adapter_id;
 	asd->match.i2c.address = address;

 	ret = v4l2_async_notifier_add_subdev(notifier, asd);
 	if (ret) {
 		kfree(asd);
 		return ERR_PTR(ret);
 	}

 	return asd;
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_i2c_subdev);

 struct v4l2_async_subdev *
 v4l2_async_notifier_add_devname_subdev(struct v4l2_async_notifier *notifier,
 				       const char *device_name,
 				       unsigned int asd_struct_size)
 {
 	struct v4l2_async_subdev *asd;
 	int ret;

 	asd = kzalloc(asd_struct_size, GFP_KERNEL);
 	if (!asd)
 		return ERR_PTR(-ENOMEM);

 	asd->match_type = V4L2_ASYNC_MATCH_DEVNAME;
 	asd->match.device_name = device_name;

 	ret = v4l2_async_notifier_add_subdev(notifier, asd);
 	if (ret) {
 		kfree(asd);
 		return ERR_PTR(ret);
 	}

 	return asd;
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_devname_subdev);

 int v4l2_async_register_subdev(struct v4l2_subdev *sd)
 {
 	struct v4l2_async_notifier *subdev_notifier;
 	struct v4l2_async_notifier *notifier;
 	int ret;

 	/*
 	 * No reference taken. The reference is held by the device
 	 * (struct v4l2_subdev.dev), and async sub-device does not
 	 * exist independently of the device at any point of time.
 	 */
 	if (!sd->fwnode && sd->dev)
 		sd->fwnode = dev_fwnode(sd->dev);

 	mutex_lock(&list_lock);

 	INIT_LIST_HEAD(&sd->async_list);

 	list_for_each_entry(notifier, &notifier_list, list) {
 		struct v4l2_device *v4l2_dev =
 			v4l2_async_notifier_find_v4l2_dev(notifier);
 		struct v4l2_async_subdev *asd;

 		if (!v4l2_dev)
 			continue;

 		asd = v4l2_async_find_match(notifier, sd);
 		if (!asd)
 			continue;

 		ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
 		if (ret)
 			goto err_unbind;

 		ret = v4l2_async_notifier_try_complete(notifier);
 		if (ret)
 			goto err_unbind;

 		goto out_unlock;
 	}

 	/* None matched, wait for hot-plugging */
 	list_add(&sd->async_list, &subdev_list);

 out_unlock:
 	mutex_unlock(&list_lock);

 	return 0;

 err_unbind:
 	/*
 	 * Complete failed. Unbind the sub-devices bound through registering
 	 * this async sub-device.
 	 */
 	subdev_notifier = v4l2_async_find_subdev_notifier(sd);
 	if (subdev_notifier)
 		v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);

 	if (sd->asd)
 		v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
 	v4l2_async_cleanup(sd);

 	mutex_unlock(&list_lock);

 	return ret;
 }
 EXPORT_SYMBOL(v4l2_async_register_subdev);

 void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
 {
 	mutex_lock(&list_lock);

 	__v4l2_async_notifier_unregister(sd->subdev_notifier);
 	__v4l2_async_notifier_cleanup(sd->subdev_notifier);
 	kfree(sd->subdev_notifier);
 	sd->subdev_notifier = NULL;

 	if (sd->asd) {
 		struct v4l2_async_notifier *notifier = sd->notifier;

 		list_add(&sd->asd->list, &notifier->waiting);

 		v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
 	}

 	v4l2_async_cleanup(sd);

 	mutex_unlock(&list_lock);
 }
 EXPORT_SYMBOL(v4l2_async_unregister_subdev);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* V4L2 asynchronous subdevice registration API
	*
	* Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/list.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/types.h>

	#include <media/v4l2-async.h>
	#include <media/v4l2-device.h>
	#include <media/v4l2-fwnode.h>
	#include <media/v4l2-subdev.h>

	static int v4l2_async_notifier_call_bound(struct v4l2_async_notifier *n,
	struct v4l2_subdev *subdev,
	struct v4l2_async_subdev *asd)
	{
	if (!n->ops \|\| !n->ops->bound)
	return 0;

	return n->ops->bound(n, subdev, asd);
	}

	static void v4l2_async_notifier_call_unbind(struct v4l2_async_notifier *n,
	struct v4l2_subdev *subdev,
	struct v4l2_async_subdev *asd)
	{
	if (!n->ops \|\| !n->ops->unbind)
	return;

	n->ops->unbind(n, subdev, asd);
	}

	static int v4l2_async_notifier_call_complete(struct v4l2_async_notifier *n)
	{
	if (!n->ops \|\| !n->ops->complete)
	return 0;

	return n->ops->complete(n);
	}

	static bool match_i2c(struct v4l2_subdev sd, struct v4l2_async_subdev asd)
	{
	#if IS_ENABLED(CONFIG_I2C)
	struct i2c_client *client = i2c_verify_client(sd->dev);

	return client &&
	asd->match.i2c.adapter_id == client->adapter->nr &&
	asd->match.i2c.address == client->addr;
	#else
	return false;
	#endif
	}

	static bool match_devname(struct v4l2_subdev *sd,
	struct v4l2_async_subdev *asd)
	{
	return !strcmp(asd->match.device_name, dev_name(sd->dev));
	}

	static bool match_fwnode(struct v4l2_subdev sd, struct v4l2_async_subdev asd)
	{
	return sd->fwnode == asd->match.fwnode;
	}

	static bool match_custom(struct v4l2_subdev sd, struct v4l2_async_subdev asd)
	{
	if (!asd->match.custom.match)
	/* Match always */
	return true;

	return asd->match.custom.match(sd->dev, asd);
	}

	static LIST_HEAD(subdev_list);
	static LIST_HEAD(notifier_list);
	static DEFINE_MUTEX(list_lock);

	static struct v4l2_async_subdev *
	v4l2_async_find_match(struct v4l2_async_notifier *notifier,
	struct v4l2_subdev *sd)
	{
	bool (match)(struct v4l2_subdev sd, struct v4l2_async_subdev *asd);
	struct v4l2_async_subdev *asd;

	list_for_each_entry(asd, &notifier->waiting, list) {
	/* bus_type has been verified valid before */
	switch (asd->match_type) {
	case V4L2_ASYNC_MATCH_CUSTOM:
	match = match_custom;
	break;
	case V4L2_ASYNC_MATCH_DEVNAME:
	match = match_devname;
	break;
	case V4L2_ASYNC_MATCH_I2C:
	match = match_i2c;
	break;
	case V4L2_ASYNC_MATCH_FWNODE:
	match = match_fwnode;
	break;
	default:
	/* Cannot happen, unless someone breaks us */
	WARN_ON(true);
	return NULL;
	}

	/* match cannot be NULL here */
	if (match(sd, asd))
	return asd;
	}

	return NULL;
	}

	/* Compare two async sub-device descriptors for equivalence */
	static bool asd_equal(struct v4l2_async_subdev *asd_x,
	struct v4l2_async_subdev *asd_y)
	{
	if (asd_x->match_type != asd_y->match_type)
	return false;

	switch (asd_x->match_type) {
	case V4L2_ASYNC_MATCH_DEVNAME:
	return strcmp(asd_x->match.device_name,
	asd_y->match.device_name) == 0;
	case V4L2_ASYNC_MATCH_I2C:
	return asd_x->match.i2c.adapter_id ==
	asd_y->match.i2c.adapter_id &&
	asd_x->match.i2c.address ==
	asd_y->match.i2c.address;
	case V4L2_ASYNC_MATCH_FWNODE:
	return asd_x->match.fwnode == asd_y->match.fwnode;
	default:
	break;
	}

	return false;
	}

	/* Find the sub-device notifier registered by a sub-device driver. */
	static struct v4l2_async_notifier *
	v4l2_async_find_subdev_notifier(struct v4l2_subdev *sd)
	{
	struct v4l2_async_notifier *n;

	list_for_each_entry(n, &notifier_list, list)
	if (n->sd == sd)
	return n;

	return NULL;
	}

	/* Get v4l2_device related to the notifier if one can be found. */
	static struct v4l2_device *
	v4l2_async_notifier_find_v4l2_dev(struct v4l2_async_notifier *notifier)
	{
	while (notifier->parent)
	notifier = notifier->parent;

	return notifier->v4l2_dev;
	}

	/*
	* Return true if all child sub-device notifiers are complete, false otherwise.
	*/
	static bool
	v4l2_async_notifier_can_complete(struct v4l2_async_notifier *notifier)
	{
	struct v4l2_subdev *sd;

	if (!list_empty(&notifier->waiting))
	return false;

	list_for_each_entry(sd, &notifier->done, async_list) {
	struct v4l2_async_notifier *subdev_notifier =
	v4l2_async_find_subdev_notifier(sd);

	if (subdev_notifier &&
	!v4l2_async_notifier_can_complete(subdev_notifier))
	return false;
	}

	return true;
	}

	/*
	* Complete the master notifier if possible. This is done when all async
	* sub-devices have been bound; v4l2_device is also available then.
	*/
	static int
	v4l2_async_notifier_try_complete(struct v4l2_async_notifier *notifier)
	{
	/* Quick check whether there are still more sub-devices here. */
	if (!list_empty(&notifier->waiting))
	return 0;

	/* Check the entire notifier tree; find the root notifier first. */
	while (notifier->parent)
	notifier = notifier->parent;

	/* This is root if it has v4l2_dev. */
	if (!notifier->v4l2_dev)
	return 0;

	/* Is everything ready? */
	if (!v4l2_async_notifier_can_complete(notifier))
	return 0;

	return v4l2_async_notifier_call_complete(notifier);
	}

	static int
	v4l2_async_notifier_try_all_subdevs(struct v4l2_async_notifier *notifier);

	static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
	struct v4l2_device *v4l2_dev,
	struct v4l2_subdev *sd,
	struct v4l2_async_subdev *asd)
	{
	struct v4l2_async_notifier *subdev_notifier;
	int ret;

	ret = v4l2_device_register_subdev(v4l2_dev, sd);
	if (ret < 0)
	return ret;

	ret = v4l2_async_notifier_call_bound(notifier, sd, asd);
	if (ret < 0) {
	v4l2_device_unregister_subdev(sd);
	return ret;
	}

	/* Remove from the waiting list */
	list_del(&asd->list);
	sd->asd = asd;
	sd->notifier = notifier;

	/* Move from the global subdevice list to notifier's done */
	list_move(&sd->async_list, &notifier->done);

	/*
	* See if the sub-device has a notifier. If not, return here.
	*/
	subdev_notifier = v4l2_async_find_subdev_notifier(sd);
	if (!subdev_notifier \|\| subdev_notifier->parent)
	return 0;

	/*
	* Proceed with checking for the sub-device notifier's async
	* sub-devices, and return the result. The error will be handled by the
	* caller.
	*/
	subdev_notifier->parent = notifier;

	return v4l2_async_notifier_try_all_subdevs(subdev_notifier);
	}

	/* Test all async sub-devices in a notifier for a match. */
	static int
	v4l2_async_notifier_try_all_subdevs(struct v4l2_async_notifier *notifier)
	{
	struct v4l2_device *v4l2_dev =
	v4l2_async_notifier_find_v4l2_dev(notifier);
	struct v4l2_subdev *sd;

	if (!v4l2_dev)
	return 0;

	again:
	list_for_each_entry(sd, &subdev_list, async_list) {
	struct v4l2_async_subdev *asd;
	int ret;

	asd = v4l2_async_find_match(notifier, sd);
	if (!asd)
	continue;

	ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
	if (ret < 0)
	return ret;

	/*
	* v4l2_async_match_notify() may lead to registering a
	* new notifier and thus changing the async subdevs
	* list. In order to proceed safely from here, restart
	* parsing the list from the beginning.
	*/
	goto again;
	}

	return 0;
	}

	static void v4l2_async_cleanup(struct v4l2_subdev *sd)
	{
	v4l2_device_unregister_subdev(sd);
	/*
	* Subdevice driver will reprobe and put the subdev back
	* onto the list
	*/
	list_del_init(&sd->async_list);
	sd->asd = NULL;
	}

	/* Unbind all sub-devices in the notifier tree. */
	static void
	v4l2_async_notifier_unbind_all_subdevs(struct v4l2_async_notifier *notifier)
	{
	struct v4l2_subdev sd, tmp;

	list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
	struct v4l2_async_notifier *subdev_notifier =
	v4l2_async_find_subdev_notifier(sd);

	if (subdev_notifier)
	v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);

	v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
	v4l2_async_cleanup(sd);

	list_move(&sd->async_list, &subdev_list);
	}

	notifier->parent = NULL;
	}

	/* See if an async sub-device can be found in a notifier's lists. */
	static bool
	__v4l2_async_notifier_has_async_subdev(struct v4l2_async_notifier *notifier,
	struct v4l2_async_subdev *asd)
	{
	struct v4l2_async_subdev *asd_y;
	struct v4l2_subdev *sd;

	list_for_each_entry(asd_y, &notifier->waiting, list)
	if (asd_equal(asd, asd_y))
	return true;

	list_for_each_entry(sd, &notifier->done, async_list) {
	if (WARN_ON(!sd->asd))
	continue;

	if (asd_equal(asd, sd->asd))
	return true;
	}

	return false;
	}

	/*
	* Find out whether an async sub-device was set up already or
	* whether it exists in a given notifier before @this_index.
	* If @this_index < 0, search the notifier's entire @asd_list.
	*/
	static bool
	v4l2_async_notifier_has_async_subdev(struct v4l2_async_notifier *notifier,
	struct v4l2_async_subdev *asd,
	int this_index)
	{
	struct v4l2_async_subdev *asd_y;
	int j = 0;

	lockdep_assert_held(&list_lock);

	/* Check that an asd is not being added more than once. */
	list_for_each_entry(asd_y, &notifier->asd_list, asd_list) {
	if (this_index >= 0 && j++ >= this_index)
	break;
	if (asd_equal(asd, asd_y))
	return true;
	}

	/* Check that an asd does not exist in other notifiers. */
	list_for_each_entry(notifier, &notifier_list, list)
	if (__v4l2_async_notifier_has_async_subdev(notifier, asd))
	return true;

	return false;
	}

	static int v4l2_async_notifier_asd_valid(struct v4l2_async_notifier *notifier,
	struct v4l2_async_subdev *asd,
	int this_index)
	{
	struct device *dev =
	notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL;

	if (!asd)
	return -EINVAL;

	switch (asd->match_type) {
	case V4L2_ASYNC_MATCH_CUSTOM:
	case V4L2_ASYNC_MATCH_DEVNAME:
	case V4L2_ASYNC_MATCH_I2C:
	case V4L2_ASYNC_MATCH_FWNODE:
	if (v4l2_async_notifier_has_async_subdev(notifier, asd,
	this_index)) {
	dev_dbg(dev, "subdev descriptor already listed in this or other notifiers\n");
	return -EEXIST;
	}
	break;
	default:
	dev_err(dev, "Invalid match type %u on %p\n",
	asd->match_type, asd);
	return -EINVAL;
	}

	return 0;
	}

	void v4l2_async_notifier_init(struct v4l2_async_notifier *notifier)
	{
	INIT_LIST_HEAD(&notifier->asd_list);
	}
	EXPORT_SYMBOL(v4l2_async_notifier_init);

	static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
	{
	struct v4l2_async_subdev *asd;
	int ret, i = 0;

	INIT_LIST_HEAD(&notifier->waiting);
	INIT_LIST_HEAD(&notifier->done);

	mutex_lock(&list_lock);

	list_for_each_entry(asd, &notifier->asd_list, asd_list) {
	ret = v4l2_async_notifier_asd_valid(notifier, asd, i++);
	if (ret)
	goto err_unlock;

	list_add_tail(&asd->list, &notifier->waiting);
	}

	ret = v4l2_async_notifier_try_all_subdevs(notifier);
	if (ret < 0)
	goto err_unbind;

	ret = v4l2_async_notifier_try_complete(notifier);
	if (ret < 0)
	goto err_unbind;

	/* Keep also completed notifiers on the list */
	list_add(&notifier->list, &notifier_list);

	mutex_unlock(&list_lock);

	return 0;

	err_unbind:
	/*
	* On failure, unbind all sub-devices registered through this notifier.
	*/
	v4l2_async_notifier_unbind_all_subdevs(notifier);

	err_unlock:
	mutex_unlock(&list_lock);

	return ret;
	}

	int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
	struct v4l2_async_notifier *notifier)
	{
	int ret;

	if (WARN_ON(!v4l2_dev \|\| notifier->sd))
	return -EINVAL;

	notifier->v4l2_dev = v4l2_dev;

	ret = __v4l2_async_notifier_register(notifier);
	if (ret)
	notifier->v4l2_dev = NULL;

	return ret;
	}
	EXPORT_SYMBOL(v4l2_async_notifier_register);

	int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
	struct v4l2_async_notifier *notifier)
	{
	int ret;

	if (WARN_ON(!sd \|\| notifier->v4l2_dev))
	return -EINVAL;

	notifier->sd = sd;

	ret = __v4l2_async_notifier_register(notifier);
	if (ret)
	notifier->sd = NULL;

	return ret;
	}
	EXPORT_SYMBOL(v4l2_async_subdev_notifier_register);

	static void
	__v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
	{
	if (!notifier \|\| (!notifier->v4l2_dev && !notifier->sd))
	return;

	v4l2_async_notifier_unbind_all_subdevs(notifier);

	notifier->sd = NULL;
	notifier->v4l2_dev = NULL;

	list_del(&notifier->list);
	}

	void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
	{
	mutex_lock(&list_lock);

	__v4l2_async_notifier_unregister(notifier);

	mutex_unlock(&list_lock);
	}
	EXPORT_SYMBOL(v4l2_async_notifier_unregister);

	static void __v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier)
	{
	struct v4l2_async_subdev asd, tmp;

	if (!notifier \|\| !notifier->asd_list.next)
	return;

	list_for_each_entry_safe(asd, tmp, &notifier->asd_list, asd_list) {
	switch (asd->match_type) {
	case V4L2_ASYNC_MATCH_FWNODE:
	fwnode_handle_put(asd->match.fwnode);
	break;
	default:
	break;
	}

	list_del(&asd->asd_list);
	kfree(asd);
	}
	}

	void v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier)
	{
	mutex_lock(&list_lock);

	__v4l2_async_notifier_cleanup(notifier);

	mutex_unlock(&list_lock);
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_cleanup);

	int v4l2_async_notifier_add_subdev(struct v4l2_async_notifier *notifier,
	struct v4l2_async_subdev *asd)
	{
	int ret;

	mutex_lock(&list_lock);

	ret = v4l2_async_notifier_asd_valid(notifier, asd, -1);
	if (ret)
	goto unlock;

	list_add_tail(&asd->asd_list, &notifier->asd_list);

	unlock:
	mutex_unlock(&list_lock);
	return ret;
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_subdev);

	struct v4l2_async_subdev *
	v4l2_async_notifier_add_fwnode_subdev(struct v4l2_async_notifier *notifier,
	struct fwnode_handle *fwnode,
	unsigned int asd_struct_size)
	{
	struct v4l2_async_subdev *asd;
	int ret;

	asd = kzalloc(asd_struct_size, GFP_KERNEL);
	if (!asd)
	return ERR_PTR(-ENOMEM);

	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
	asd->match.fwnode = fwnode_handle_get(fwnode);

	ret = v4l2_async_notifier_add_subdev(notifier, asd);
	if (ret) {
	fwnode_handle_put(fwnode);
	kfree(asd);
	return ERR_PTR(ret);
	}

	return asd;
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_fwnode_subdev);

	int
	v4l2_async_notifier_add_fwnode_remote_subdev(struct v4l2_async_notifier *notif,
	struct fwnode_handle *endpoint,
	struct v4l2_async_subdev *asd)
	{
	struct fwnode_handle *remote;
	int ret;

	remote = fwnode_graph_get_remote_port_parent(endpoint);
	if (!remote)
	return -ENOTCONN;

	asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
	asd->match.fwnode = remote;

	ret = v4l2_async_notifier_add_subdev(notif, asd);
	if (ret)
	fwnode_handle_put(remote);

	return ret;
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_fwnode_remote_subdev);

	struct v4l2_async_subdev *
	v4l2_async_notifier_add_i2c_subdev(struct v4l2_async_notifier *notifier,
	int adapter_id, unsigned short address,
	unsigned int asd_struct_size)
	{
	struct v4l2_async_subdev *asd;
	int ret;

	asd = kzalloc(asd_struct_size, GFP_KERNEL);
	if (!asd)
	return ERR_PTR(-ENOMEM);

	asd->match_type = V4L2_ASYNC_MATCH_I2C;
	asd->match.i2c.adapter_id = adapter_id;
	asd->match.i2c.address = address;

	ret = v4l2_async_notifier_add_subdev(notifier, asd);
	if (ret) {
	kfree(asd);
	return ERR_PTR(ret);
	}

	return asd;
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_i2c_subdev);

	struct v4l2_async_subdev *
	v4l2_async_notifier_add_devname_subdev(struct v4l2_async_notifier *notifier,
	const char *device_name,
	unsigned int asd_struct_size)
	{
	struct v4l2_async_subdev *asd;
	int ret;

	asd = kzalloc(asd_struct_size, GFP_KERNEL);
	if (!asd)
	return ERR_PTR(-ENOMEM);

	asd->match_type = V4L2_ASYNC_MATCH_DEVNAME;
	asd->match.device_name = device_name;

	ret = v4l2_async_notifier_add_subdev(notifier, asd);
	if (ret) {
	kfree(asd);
	return ERR_PTR(ret);
	}

	return asd;
	}
	EXPORT_SYMBOL_GPL(v4l2_async_notifier_add_devname_subdev);

	int v4l2_async_register_subdev(struct v4l2_subdev *sd)
	{
	struct v4l2_async_notifier *subdev_notifier;
	struct v4l2_async_notifier *notifier;
	int ret;

	/*
	* No reference taken. The reference is held by the device
	* (struct v4l2_subdev.dev), and async sub-device does not
	* exist independently of the device at any point of time.
	*/
	if (!sd->fwnode && sd->dev)
	sd->fwnode = dev_fwnode(sd->dev);

	mutex_lock(&list_lock);

	INIT_LIST_HEAD(&sd->async_list);

	list_for_each_entry(notifier, &notifier_list, list) {
	struct v4l2_device *v4l2_dev =
	v4l2_async_notifier_find_v4l2_dev(notifier);
	struct v4l2_async_subdev *asd;

	if (!v4l2_dev)
	continue;

	asd = v4l2_async_find_match(notifier, sd);
	if (!asd)
	continue;

	ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
	if (ret)
	goto err_unbind;

	ret = v4l2_async_notifier_try_complete(notifier);
	if (ret)
	goto err_unbind;

	goto out_unlock;
	}

	/* None matched, wait for hot-plugging */
	list_add(&sd->async_list, &subdev_list);

	out_unlock:
	mutex_unlock(&list_lock);

	return 0;

	err_unbind:
	/*
	* Complete failed. Unbind the sub-devices bound through registering
	* this async sub-device.
	*/
	subdev_notifier = v4l2_async_find_subdev_notifier(sd);
	if (subdev_notifier)
	v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);

	if (sd->asd)
	v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
	v4l2_async_cleanup(sd);

	mutex_unlock(&list_lock);

	return ret;
	}
	EXPORT_SYMBOL(v4l2_async_register_subdev);

	void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
	{
	mutex_lock(&list_lock);

	__v4l2_async_notifier_unregister(sd->subdev_notifier);
	__v4l2_async_notifier_cleanup(sd->subdev_notifier);
	kfree(sd->subdev_notifier);
	sd->subdev_notifier = NULL;

	if (sd->asd) {
	struct v4l2_async_notifier *notifier = sd->notifier;

	list_add(&sd->asd->list, &notifier->waiting);

	v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
	}

	v4l2_async_cleanup(sd);

	mutex_unlock(&list_lock);
	}
	EXPORT_SYMBOL(v4l2_async_unregister_subdev);