1 // SPDX-License-Identifier: GPL-2.0
3  * class.c - basic device class management
5  * Copyright (c) 2002-3 Patrick Mochel
6  * Copyright (c) 2002-3 Open Source Development Labs
7  * Copyright (c) 2003-2004 Greg Kroah-Hartman
8  * Copyright (c) 2003-2004 IBM Corp.
11 #include <linux/device/class.h>
12 #include <linux/device.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/string.h>
16 #include <linux/kdev_t.h>
17 #include <linux/err.h>
18 #include <linux/slab.h>
19 #include <linux/blkdev.h>
20 #include <linux/mutex.h>
21 #include "base.h"
23 /* /sys/class */
29  * class_to_subsys - Turn a struct class into a struct subsys_private
31  * @class: pointer to the struct bus_type to look up
34  * the external struct class pointer.  This function walks the list of
36  * internal struct subsys_private that relates to that class.
42 struct subsys_private *class_to_subsys(const struct class *class)  in class_to_subsys()  argument
47 	if (!class || !class_kset)  in class_to_subsys()
50 	spin_lock(&class_kset->list_lock);  in class_to_subsys()
52 	if (list_empty(&class_kset->list))  in class_to_subsys()
55 	list_for_each_entry(kobj, &class_kset->list, entry) {  in class_to_subsys()
59 		if (sp->class == class)  in class_to_subsys()
65 	spin_unlock(&class_kset->list_lock);  in class_to_subsys()
74 	ssize_t ret = -EIO;  in class_attr_show()
76 	if (class_attr->show)  in class_attr_show()
77 		ret = class_attr->show(cp->class, class_attr, buf);  in class_attr_show()
86 	ssize_t ret = -EIO;  in class_attr_store()
88 	if (class_attr->store)  in class_attr_store()
89 		ret = class_attr->store(cp->class, class_attr, buf, count);  in class_attr_store()
96 	const struct class *class = cp->class;  in class_release()  local
98 	pr_debug("class '%s': release.\n", class->name);  in class_release()
100 	if (class->class_release)  in class_release()
101 		class->class_release(class);  in class_release()
103 		pr_debug("class '%s' does not have a release() function, "  in class_release()
104 			 "be careful\n", class->name);  in class_release()
106 	lockdep_unregister_key(&cp->lock_key);  in class_release()
113 	const struct class *class = cp->class;  in class_child_ns_type()  local
115 	return class->ns_type;  in class_child_ns_type()
129 int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,  in class_create_file_ns()
136 		return -EINVAL;  in class_create_file_ns()
138 	error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);  in class_create_file_ns()
145 void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,  in class_remove_file_ns()
153 	sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);  in class_remove_file_ns()
161 	return p->device;  in klist_class_to_dev()
178 int class_register(const struct class *cls)  in class_register()
184 	pr_debug("device class '%s': registering\n", cls->name);  in class_register()
186 	if (cls->ns_type && !cls->namespace) {  in class_register()
187 		pr_err("%s: class '%s' does not have namespace\n",  in class_register()
188 		       __func__, cls->name);  in class_register()
189 		return -EINVAL;  in class_register()
191 	if (!cls->ns_type && cls->namespace) {  in class_register()
192 		pr_err("%s: class '%s' does not have ns_type\n",  in class_register()
193 		       __func__, cls->name);  in class_register()
194 		return -EINVAL;  in class_register()
199 		return -ENOMEM;  in class_register()
200 	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);  in class_register()
201 	INIT_LIST_HEAD(&cp->interfaces);  in class_register()
202 	kset_init(&cp->glue_dirs);  in class_register()
203 	key = &cp->lock_key;  in class_register()
205 	__mutex_init(&cp->mutex, "subsys mutex", key);  in class_register()
206 	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);  in class_register()
210 	cp->subsys.kobj.kset = class_kset;  in class_register()
211 	cp->subsys.kobj.ktype = &class_ktype;  in class_register()
212 	cp->class = cls;  in class_register()
214 	error = kset_register(&cp->subsys);  in class_register()
218 	error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);  in class_register()
220 		kobject_del(&cp->subsys.kobj);  in class_register()
221 		kfree_const(cp->subsys.kobj.name);  in class_register()
233 void class_unregister(const struct class *cls)  in class_unregister()
240 	pr_debug("device class '%s': unregistering\n", cls->name);  in class_unregister()
242 	sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);  in class_unregister()
243 	kset_unregister(&sp->subsys);  in class_unregister()
248 static void class_create_release(const struct class *cls)  in class_create_release()
250 	pr_debug("%s called for %s\n", __func__, cls->name);  in class_create_release()
255  * class_create - create a struct class structure
256  * @name: pointer to a string for the name of this class.
258  * This is used to create a struct class pointer that can then be used
261  * Returns &struct class pointer on success, or ERR_PTR() on error.
266 struct class *class_create(const char *name)  in class_create()
268 	struct class *cls;  in class_create()
273 		retval = -ENOMEM;  in class_create()
277 	cls->name = name;  in class_create()
278 	cls->class_release = class_create_release;  in class_create()
293  * class_destroy - destroys a struct class structure
294  * @cls: pointer to the struct class that is to be destroyed
299 void class_destroy(const struct class *cls)  in class_destroy()
309  * class_dev_iter_init - initialize class device iterator
310  * @iter: class iterator to initialize
311  * @class: the class we wanna iterate over
315  * Initialize class iterator @iter such that it iterates over devices
316  * of @class.  If @start is set, the list iteration will start there,
320 void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,  in class_dev_iter_init()  argument
323 	struct subsys_private *sp = class_to_subsys(class);  in class_dev_iter_init()
328 		pr_crit("%s: class %p was not registered yet\n",  in class_dev_iter_init()
329 			__func__, class);  in class_dev_iter_init()
334 		start_knode = &start->p->knode_class;  in class_dev_iter_init()
335 	klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);  in class_dev_iter_init()
336 	iter->type = type;  in class_dev_iter_init()
337 	iter->sp = sp;  in class_dev_iter_init()
342  * class_dev_iter_next - iterate to the next device
343  * @iter: class iterator to proceed
351  * calling back into class code.
358 	if (!iter->sp)  in class_dev_iter_next()
362 		knode = klist_next(&iter->ki);  in class_dev_iter_next()
366 		if (!iter->type || iter->type == dev->type)  in class_dev_iter_next()
373  * class_dev_iter_exit - finish iteration
374  * @iter: class iterator to finish
381 	klist_iter_exit(&iter->ki);  in class_dev_iter_exit()
382 	subsys_put(iter->sp);  in class_dev_iter_exit()
387  * class_for_each_device - device iterator
388  * @class: the class we're iterating
393  * Iterate over @class's list of devices, and call @fn for each,
401  * @fn is allowed to do anything including calling back into class
404 int class_for_each_device(const struct class *class, const struct device *start,  in class_for_each_device()  argument
407 	struct subsys_private *sp = class_to_subsys(class);  in class_for_each_device()
412 	if (!class)  in class_for_each_device()
413 		return -EINVAL;  in class_for_each_device()
415 		WARN(1, "%s called for class '%s' before it was registered",  in class_for_each_device()
416 		     __func__, class->name);  in class_for_each_device()
417 		return -EINVAL;  in class_for_each_device()
420 	class_dev_iter_init(&iter, class, start, NULL);  in class_for_each_device()
434  * class_find_device - device iterator for locating a particular device
435  * @class: the class we're iterating
444  * The callback should return 0 if the device doesn't match and non-zero
445  * if it does.  If the callback returns non-zero, this function will
450  * @match is allowed to do anything including calling back into class
453 struct device *class_find_device(const struct class *class, const struct device *start,  in class_find_device()  argument
456 	struct subsys_private *sp = class_to_subsys(class);  in class_find_device()
460 	if (!class)  in class_find_device()
463 		WARN(1, "%s called for class '%s' before it was registered",  in class_find_device()
464 		     __func__, class->name);  in class_find_device()
468 	class_dev_iter_init(&iter, class, start, NULL);  in class_find_device()
485 	const struct class *parent;  in class_interface_register()
489 	if (!class_intf || !class_intf->class)  in class_interface_register()
490 		return -ENODEV;  in class_interface_register()
492 	parent = class_intf->class;  in class_interface_register()
495 		return -EINVAL;  in class_interface_register()
502 	mutex_lock(&sp->mutex);  in class_interface_register()
503 	list_add_tail(&class_intf->node, &sp->interfaces);  in class_interface_register()
504 	if (class_intf->add_dev) {  in class_interface_register()
507 			class_intf->add_dev(dev);  in class_interface_register()
510 	mutex_unlock(&sp->mutex);  in class_interface_register()
519 	const struct class *parent = class_intf->class;  in class_interface_unregister()
530 	mutex_lock(&sp->mutex);  in class_interface_unregister()
531 	list_del_init(&class_intf->node);  in class_interface_unregister()
532 	if (class_intf->remove_dev) {  in class_interface_unregister()
535 			class_intf->remove_dev(dev);  in class_interface_unregister()
538 	mutex_unlock(&sp->mutex);  in class_interface_unregister()
550 ssize_t show_class_attr_string(const struct class *class,  in show_class_attr_string()  argument
556 	return sysfs_emit(buf, "%s\n", cs->str);  in show_class_attr_string()
566  * class_compat_register - register a compatibility class
567  * @name: the name of the class
569  * Compatibility class are meant as a temporary user-space compatibility
570  * workaround when converting a family of class devices to a bus devices.
579 	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);  in class_compat_register()
580 	if (!cls->kobj) {  in class_compat_register()
589  * class_compat_unregister - unregister a compatibility class
590  * @cls: the class to unregister
594 	kobject_put(cls->kobj);  in class_compat_unregister()
600  * class_compat_create_link - create a compatibility class device link to
602  * @cls: the compatibility class
607 	return sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));  in class_compat_create_link()
612  * class_compat_remove_link - remove a compatibility class device link to
614  * @cls: the compatibility class
619 	sysfs_remove_link(cls->kobj, dev_name(dev));  in class_compat_remove_link()
624  * class_is_registered - determine if at this moment in time, a class is
626  * @class: the class to check
628  * Returns a boolean to state if the class is registered in the driver core
631  * to determine if the specific class has been registered yet or not).
635 bool class_is_registered(const struct class *class)  in class_is_registered()  argument
637 	struct subsys_private *sp = class_to_subsys(class);  in class_is_registered()
650 	class_kset = kset_create_and_add("class", NULL, NULL);  in classes_init()
652 		return -ENOMEM;  in classes_init()