// SPDX-License-Identifier: GPL-2.0/* * class.c - basic device class management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * Copyright (c) 2003-2004 Greg Kroah-Hartman * Copyright (c) 2003-2004 IBM Corp. */ #include <linux/device/class.h>#include <linux/device.h>#include <linux/module.h>#include <linux/init.h>#include <linux/string.h>#include <linux/kdev_t.h>#include <linux/err.h>#include <linux/slab.h>#include <linux/blkdev.h>#include <linux/mutex.h>#include "base.h" /* /sys/class */static struct kset *class_kset; #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr) /** * class_to_subsys - Turn a struct class into a struct subsys_private * * @class: pointer to the struct bus_type to look up * * The driver core internals need to work on the subsys_private structure, not * the external struct class pointer.  This function walks the list of * registered classes in the system and finds the matching one and returns the * internal struct subsys_private that relates to that class. * * Note, the reference count of the return value is INCREMENTED if it is not * NULL.  A call to subsys_put() must be done when finished with the pointer in * order for it to be properly freed. */struct subsys_private *class_to_subsys(const struct class *class){	struct subsys_private *sp = NULL;	struct kobject *kobj; 	if (!class || !class_kset)		return NULL; 	spin_lock(&class_kset->list_lock); 	if (list_empty(&class_kset->list))		goto done; 	list_for_each_entry(kobj, &class_kset->list, entry) {		struct kset *kset = container_of(kobj, struct kset, kobj); 		sp = container_of_const(kset, struct subsys_private, subsys);		if (sp->class == class)			goto done;	}	sp = NULL;done:	sp = subsys_get(sp);	spin_unlock(&class_kset->list_lock);	return sp;} static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,			       char *buf){	struct class_attribute *class_attr = to_class_attr(attr);	struct subsys_private *cp = to_subsys_private(kobj);	ssize_t ret = -EIO; 	if (class_attr->show)		ret = class_attr->show(cp->class, class_attr, buf);	return ret;} static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,				const char *buf, size_t count){	struct class_attribute *class_attr = to_class_attr(attr);	struct subsys_private *cp = to_subsys_private(kobj);	ssize_t ret = -EIO; 	if (class_attr->store)		ret = class_attr->store(cp->class, class_attr, buf, count);	return ret;} static void class_release(struct kobject *kobj){	struct subsys_private *cp = to_subsys_private(kobj);	const struct class *class = cp->class; 	pr_debug("class '%s': release.\n", class->name); 	if (class->class_release)		class->class_release(class);	else		pr_debug("class '%s' does not have a release() function, "			 "be careful\n", class->name); 	lockdep_unregister_key(&cp->lock_key);	kfree(cp);} static const struct kobj_ns_type_operations *class_child_ns_type(const struct kobject *kobj){	const struct subsys_private *cp = to_subsys_private(kobj);	const struct class *class = cp->class; 	return class->ns_type;} static const struct sysfs_ops class_sysfs_ops = {	.show	   = class_attr_show,	.store	   = class_attr_store,}; static const struct kobj_type class_ktype = {	.sysfs_ops	= &class_sysfs_ops,	.release	= class_release,	.child_ns_type	= class_child_ns_type,}; int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,			 const struct ns_common *ns){	struct subsys_private *sp = class_to_subsys(cls);	int error; 	if (!sp)		return -EINVAL; 	error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);	subsys_put(sp); 	return error;}EXPORT_SYMBOL_GPL(class_create_file_ns); void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,			  const struct ns_common *ns){	struct subsys_private *sp = class_to_subsys(cls); 	if (!sp)		return; 	sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);	subsys_put(sp);}EXPORT_SYMBOL_GPL(class_remove_file_ns); static struct device *klist_class_to_dev(struct klist_node *n){	struct device_private *p = to_device_private_class(n);	return p->device;} static void klist_class_dev_get(struct klist_node *n){	struct device *dev = klist_class_to_dev(n); 	get_device(dev);} static void klist_class_dev_put(struct klist_node *n){	struct device *dev = klist_class_to_dev(n); 	put_device(dev);} int class_register(const struct class *cls){	struct subsys_private *cp;	struct lock_class_key *key;	int error; 	pr_debug("device class '%s': registering\n", cls->name); 	if (cls->ns_type && !cls->namespace) {		pr_err("%s: class '%s' does not have namespace\n",		       __func__, cls->name);		return -EINVAL;	}	if (!cls->ns_type && cls->namespace) {		pr_err("%s: class '%s' does not have ns_type\n",		       __func__, cls->name);		return -EINVAL;	} 	cp = kzalloc_obj(*cp);	if (!cp)		return -ENOMEM;	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);	INIT_LIST_HEAD(&cp->interfaces);	kset_init(&cp->glue_dirs);	key = &cp->lock_key;	lockdep_register_key(key);	__mutex_init(&cp->mutex, "subsys mutex", key);	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);	if (error)		goto err_out; 	cp->subsys.kobj.kset = class_kset;	cp->subsys.kobj.ktype = &class_ktype;	cp->class = cls; 	error = kset_register(&cp->subsys);	if (error)		goto err_out; 	error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);	if (error) {		kobject_del(&cp->subsys.kobj);		kfree_const(cp->subsys.kobj.name);		goto err_out;	}	return 0; err_out:	lockdep_unregister_key(key);	kfree(cp);	return error;}EXPORT_SYMBOL_GPL(class_register); void class_unregister(const struct class *cls){	struct subsys_private *sp = class_to_subsys(cls); 	if (!sp)		return; 	pr_debug("device class '%s': unregistering\n", cls->name); 	sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);	kset_unregister(&sp->subsys);	subsys_put(sp);}EXPORT_SYMBOL_GPL(class_unregister); static void class_create_release(const struct class *cls){	pr_debug("%s called for %s\n", __func__, cls->name);	kfree(cls);} /** * class_create - create a struct class structure * @name: pointer to a string for the name of this class. * * This is used to create a struct class pointer that can then be used * in calls to device_create(). * * Returns &struct class pointer on success, or ERR_PTR() on error. * * Note, the pointer created here is to be destroyed when finished by * making a call to class_destroy(). */struct class *class_create(const char *name){	struct class *cls;	int retval; 	cls = kzalloc_obj(*cls);	if (!cls) {		retval = -ENOMEM;		goto error;	} 	cls->name = name;	cls->class_release = class_create_release; 	retval = class_register(cls);	if (retval)		goto error; 	return cls; error:	kfree(cls);	return ERR_PTR(retval);}EXPORT_SYMBOL_GPL(class_create); /** * class_destroy - destroys a struct class structure * @cls: pointer to the struct class that is to be destroyed * * Note, the pointer to be destroyed must have been created with a call * to class_create(). */void class_destroy(const struct class *cls){	if (IS_ERR_OR_NULL(cls))		return; 	class_unregister(cls);}EXPORT_SYMBOL_GPL(class_destroy); /** * class_dev_iter_init - initialize class device iterator * @iter: class iterator to initialize * @class: the class we wanna iterate over * @start: the device to start iterating from, if any * @type: device_type of the devices to iterate over, NULL for all * * Initialize class iterator @iter such that it iterates over devices * of @class.  If @start is set, the list iteration will start there, * otherwise if it is NULL, the iteration starts at the beginning of * the list. */void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,			 const struct device *start, const struct device_type *type){	struct subsys_private *sp = class_to_subsys(class);	struct klist_node *start_knode = NULL; 	memset(iter, 0, sizeof(*iter));	if (!sp) {		pr_crit("%s: class %p was not registered yet\n",			__func__, class);		return;	} 	if (start)		start_knode = &start->p->knode_class;	klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);	iter->type = type;	iter->sp = sp;}EXPORT_SYMBOL_GPL(class_dev_iter_init); /** * class_dev_iter_next - iterate to the next device * @iter: class iterator to proceed * * Proceed @iter to the next device and return it.  Returns NULL if * iteration is complete. * * The returned device is referenced and won't be released till * iterator is proceed to the next device or exited.  The caller is * free to do whatever it wants to do with the device including * calling back into class code. */struct device *class_dev_iter_next(struct class_dev_iter *iter){	struct klist_node *knode;	struct device *dev; 	if (!iter->sp)		return NULL; 	while (1) {		knode = klist_next(&iter->ki);		if (!knode)			return NULL;		dev = klist_class_to_dev(knode);		if (!iter->type || iter->type == dev->type)			return dev;	}}EXPORT_SYMBOL_GPL(class_dev_iter_next); /** * class_dev_iter_exit - finish iteration * @iter: class iterator to finish * * Finish an iteration.  Always call this function after iteration is * complete whether the iteration ran till the end or not. */void class_dev_iter_exit(struct class_dev_iter *iter){	klist_iter_exit(&iter->ki);	subsys_put(iter->sp);}EXPORT_SYMBOL_GPL(class_dev_iter_exit); /** * class_for_each_device - device iterator * @class: the class we're iterating * @start: the device to start with in the list, if any. * @data: data for the callback * @fn: function to be called for each device * * Iterate over @class's list of devices, and call @fn for each, * passing it @data.  If @start is set, the list iteration will start * there, otherwise if it is NULL, the iteration starts at the * beginning of the list. * * We check the return of @fn each time. If it returns anything * other than 0, we break out and return that value. * * @fn is allowed to do anything including calling back into class * code.  There's no locking restriction. */int class_for_each_device(const struct class *class, const struct device *start,			  void *data, device_iter_t fn){	struct subsys_private *sp = class_to_subsys(class);	struct class_dev_iter iter;	struct device *dev;	int error = 0; 	if (!class)		return -EINVAL;	if (!sp) {		WARN(1, "%s called for class '%s' before it was registered",		     __func__, class->name);		return -EINVAL;	} 	class_dev_iter_init(&iter, class, start, NULL);	while ((dev = class_dev_iter_next(&iter))) {		error = fn(dev, data);		if (error)			break;	}	class_dev_iter_exit(&iter);	subsys_put(sp); 	return error;}EXPORT_SYMBOL_GPL(class_for_each_device); /** * class_find_device - device iterator for locating a particular device * @class: the class we're iterating * @start: Device to begin with * @data: data for the match function * @match: function to check device * * This is similar to the class_for_each_dev() function above, but it * returns a reference to a device that is 'found' for later use, as * determined by the @match callback. * * The callback should return 0 if the device doesn't match and non-zero * if it does.  If the callback returns non-zero, this function will * return to the caller and not iterate over any more devices. * * Note, you will need to drop the reference with put_device() after use. * * @match is allowed to do anything including calling back into class * code.  There's no locking restriction. */struct device *class_find_device(const struct class *class, const struct device *start,				 const void *data, device_match_t match){	struct subsys_private *sp = class_to_subsys(class);	struct class_dev_iter iter;	struct device *dev; 	if (!class)		return NULL;	if (!sp) {		WARN(1, "%s called for class '%s' before it was registered",		     __func__, class->name);		return NULL;	} 	class_dev_iter_init(&iter, class, start, NULL);	while ((dev = class_dev_iter_next(&iter))) {		if (match(dev, data)) {			get_device(dev);			break;		}	}	class_dev_iter_exit(&iter);	subsys_put(sp); 	return dev;}EXPORT_SYMBOL_GPL(class_find_device); int class_interface_register(struct class_interface *class_intf){	struct subsys_private *sp;	const struct class *parent;	struct class_dev_iter iter;	struct device *dev; 	if (!class_intf || !class_intf->class)		return -ENODEV; 	parent = class_intf->class;	sp = class_to_subsys(parent);	if (!sp)		return -EINVAL; 	/*	 * Reference in sp is now incremented and will be dropped when	 * the interface is removed in the call to class_interface_unregister()	 */

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