// SPDX-License-Identifier: GPL-2.0/* * attribute_container.c - implementation of a simple container for classes * * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com> * * The basic idea here is to enable a device to be attached to an * aritrary numer of classes without having to allocate storage for them. * Instead, the contained classes select the devices they need to attach * to via a matching function. */ #include <linux/attribute_container.h>#include <linux/device.h>#include <linux/kernel.h>#include <linux/slab.h>#include <linux/list.h>#include <linux/module.h>#include <linux/mutex.h> #include "base.h" /* This is a private structure used to tie the classdev and the * container .. it should never be visible outside this file */struct internal_container {	struct klist_node node;	struct attribute_container *cont;	struct device classdev;}; static void internal_container_klist_get(struct klist_node *n){	struct internal_container *ic =		container_of(n, struct internal_container, node);	get_device(&ic->classdev);} static void internal_container_klist_put(struct klist_node *n){	struct internal_container *ic =		container_of(n, struct internal_container, node);	put_device(&ic->classdev);}  /** * attribute_container_classdev_to_container - given a classdev, return the container * * @classdev: the class device created by attribute_container_add_device. * * Returns the container associated with this classdev. */struct attribute_container *attribute_container_classdev_to_container(struct device *classdev){	struct internal_container *ic =		container_of(classdev, struct internal_container, classdev);	return ic->cont;}EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container); static LIST_HEAD(attribute_container_list); static DEFINE_MUTEX(attribute_container_mutex); /** * attribute_container_register - register an attribute container * * @cont: The container to register.  This must be allocated by the *        callee and should also be zeroed by it. */intattribute_container_register(struct attribute_container *cont){	INIT_LIST_HEAD(&cont->node);	klist_init(&cont->containers, internal_container_klist_get,		   internal_container_klist_put); 	mutex_lock(&attribute_container_mutex);	list_add_tail(&cont->node, &attribute_container_list);	mutex_unlock(&attribute_container_mutex); 	return 0;}EXPORT_SYMBOL_GPL(attribute_container_register); /** * attribute_container_unregister - remove a container registration * * @cont: previously registered container to remove */intattribute_container_unregister(struct attribute_container *cont){	int retval = -EBUSY; 	mutex_lock(&attribute_container_mutex);	spin_lock(&cont->containers.k_lock);	if (!list_empty(&cont->containers.k_list))		goto out;	retval = 0;	list_del(&cont->node); out:	spin_unlock(&cont->containers.k_lock);	mutex_unlock(&attribute_container_mutex);	return retval; }EXPORT_SYMBOL_GPL(attribute_container_unregister); /* private function used as class release */static void attribute_container_release(struct device *classdev){	struct internal_container *ic		= container_of(classdev, struct internal_container, classdev);	struct device *dev = classdev->parent; 	kfree(ic);	put_device(dev);} /** * attribute_container_add_device - see if any container is interested in dev * * @dev: device to add attributes to * @fn:	 function to trigger addition of class device. * * This function allocates storage for the class device(s) to be * attached to dev (one for each matching attribute_container).  If no * fn is provided, the code will simply register the class device via * device_add.  If a function is provided, it is expected to add * the class device at the appropriate time.  One of the things that * might be necessary is to allocate and initialise the classdev and * then add it a later time.  To do this, call this routine for * allocation and initialisation and then use * attribute_container_device_trigger() to call device_add() on * it.  Note: after this, the class device contains a reference to dev * which is not relinquished until the release of the classdev. */voidattribute_container_add_device(struct device *dev,			       int (*fn)(struct attribute_container *,					 struct device *,					 struct device *)){	struct attribute_container *cont; 	mutex_lock(&attribute_container_mutex);	list_for_each_entry(cont, &attribute_container_list, node) {		struct internal_container *ic; 		if (attribute_container_no_classdevs(cont))			continue; 		if (!cont->match(cont, dev))			continue; 		ic = kzalloc(sizeof(*ic), GFP_KERNEL);		if (!ic) {			dev_err(dev, "failed to allocate class container\n");			continue;		} 		ic->cont = cont;		device_initialize(&ic->classdev);		ic->classdev.parent = get_device(dev);		ic->classdev.class = cont->class;		cont->class->dev_release = attribute_container_release;		dev_set_name(&ic->classdev, "%s", dev_name(dev));		if (fn)			fn(cont, dev, &ic->classdev);		else			attribute_container_add_class_device(&ic->classdev);		klist_add_tail(&ic->node, &cont->containers);	}	mutex_unlock(&attribute_container_mutex);} /* FIXME: can't break out of this unless klist_iter_exit is also * called before doing the break */#define klist_for_each_entry(pos, head, member, iter) \	for (klist_iter_init(head, iter); (pos = ({ \		struct klist_node *n = klist_next(iter); \		n ? container_of(n, typeof(*pos), member) : \			({ klist_iter_exit(iter) ; NULL; }); \	})) != NULL;)  /** * attribute_container_remove_device - make device eligible for removal. * * @dev:  The generic device * @fn:	  A function to call to remove the device * * This routine triggers device removal.  If fn is NULL, then it is * simply done via device_unregister (note that if something * still has a reference to the classdev, then the memory occupied * will not be freed until the classdev is released).  If you want a * two phase release: remove from visibility and then delete the * device, then you should use this routine with a fn that calls * device_del() and then use attribute_container_device_trigger() * to do the final put on the classdev. */voidattribute_container_remove_device(struct device *dev,				  void (*fn)(struct attribute_container *,					     struct device *,					     struct device *)){	struct attribute_container *cont; 	mutex_lock(&attribute_container_mutex);	list_for_each_entry(cont, &attribute_container_list, node) {		struct internal_container *ic;		struct klist_iter iter; 		if (attribute_container_no_classdevs(cont))			continue; 		if (!cont->match(cont, dev))			continue; 		klist_for_each_entry(ic, &cont->containers, node, &iter) {			if (dev != ic->classdev.parent)				continue;			klist_del(&ic->node);			if (fn)				fn(cont, dev, &ic->classdev);			else {				attribute_container_remove_attrs(&ic->classdev);				device_unregister(&ic->classdev);			}		}	}	mutex_unlock(&attribute_container_mutex);} /** * attribute_container_device_trigger - execute a trigger for each matching classdev * * @dev:  The generic device to run the trigger for * @fn	  the function to execute for each classdev. * * This function is for executing a trigger when you need to know both * the container and the classdev.  If you only care about the * container, then use attribute_container_trigger() instead. */voidattribute_container_device_trigger(struct device *dev,				   int (*fn)(struct attribute_container *,					     struct device *,					     struct device *)){	struct attribute_container *cont; 	mutex_lock(&attribute_container_mutex);	list_for_each_entry(cont, &attribute_container_list, node) {		struct internal_container *ic;		struct klist_iter iter; 		if (!cont->match(cont, dev))			continue; 		if (attribute_container_no_classdevs(cont)) {			fn(cont, dev, NULL);			continue;		} 		klist_for_each_entry(ic, &cont->containers, node, &iter) {			if (dev == ic->classdev.parent)				fn(cont, dev, &ic->classdev);		}	}	mutex_unlock(&attribute_container_mutex);} /** * attribute_container_trigger - trigger a function for each matching container * * @dev:  The generic device to activate the trigger for * @fn:	  the function to trigger * * This routine triggers a function that only needs to know the * matching containers (not the classdev) associated with a device. * It is more lightweight than attribute_container_device_trigger, so * should be used in preference unless the triggering function * actually needs to know the classdev. */voidattribute_container_trigger(struct device *dev,			    int (*fn)(struct attribute_container *,				      struct device *)){	struct attribute_container *cont; 	mutex_lock(&attribute_container_mutex);	list_for_each_entry(cont, &attribute_container_list, node) {		if (cont->match(cont, dev))			fn(cont, dev);	}	mutex_unlock(&attribute_container_mutex);} /** * attribute_container_add_attrs - add attributes * * @classdev: The class device * * This simply creates all the class device sysfs files from the * attributes listed in the container */intattribute_container_add_attrs(struct device *classdev){	struct attribute_container *cont =		attribute_container_classdev_to_container(classdev);	struct device_attribute **attrs = cont->attrs;	int i, error; 	BUG_ON(attrs && cont->grp); 	if (!attrs && !cont->grp)		return 0; 	if (cont->grp)		return sysfs_create_group(&classdev->kobj, cont->grp); 	for (i = 0; attrs[i]; i++) {		sysfs_attr_init(&attrs[i]->attr);		error = device_create_file(classdev, attrs[i]);		if (error)			return error;	} 	return 0;} /** * attribute_container_add_class_device - same function as device_add * * @classdev:	the class device to add * * This performs essentially the same function as device_add except for * attribute containers, namely add the classdev to the system and then * create the attribute files */intattribute_container_add_class_device(struct device *classdev){	int error = device_add(classdev); 	if (error)		return error;	return attribute_container_add_attrs(classdev);} /** * attribute_container_add_class_device_adapter - simple adapter for triggers * * This function is identical to attribute_container_add_class_device except * that it is designed to be called from the triggers */intattribute_container_add_class_device_adapter(struct attribute_container *cont,					     struct device *dev,					     struct device *classdev){	return attribute_container_add_class_device(classdev);} /** * attribute_container_remove_attrs - remove any attribute files * * @classdev: The class device to remove the files from * */voidattribute_container_remove_attrs(struct device *classdev){	struct attribute_container *cont =		attribute_container_classdev_to_container(classdev);	struct device_attribute **attrs = cont->attrs;	int i; 	if (!attrs && !cont->grp)		return; 	if (cont->grp) {		sysfs_remove_group(&classdev->kobj, cont->grp);		return ;	} 	for (i = 0; attrs[i]; i++)		device_remove_file(classdev, attrs[i]);} /** * attribute_container_class_device_del - equivalent of class_device_del * * @classdev: the class device * * This function simply removes all the attribute files and then calls * device_del. */voidattribute_container_class_device_del(struct device *classdev){	attribute_container_remove_attrs(classdev);	device_del(classdev);} /** * attribute_container_find_class_device - find the corresponding class_device * * @cont:	the container * @dev:	the generic device * * Looks up the device in the container's list of class devices and returns * the corresponding class_device. */struct device *attribute_container_find_class_device(struct attribute_container *cont,				      struct device *dev){	struct device *cdev = NULL;	struct internal_container *ic;	struct klist_iter iter; 	klist_for_each_entry(ic, &cont->containers, node, &iter) {		if (ic->classdev.parent == dev) {			cdev = &ic->classdev;			/* FIXME: must exit iterator then break */			klist_iter_exit(&iter);			break;		}	} 	return cdev;}EXPORT_SYMBOL_GPL(attribute_container_find_class_device);