2 * class.c - basic device class management
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
6 * Copyright (c) 2003-2004 Greg Kroah-Hartman
7 * Copyright (c) 2003-2004 IBM Corp.
9 * This file is released under the GPLv2
13 #include <linux/device.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
17 #include <linux/kdev_t.h>
18 #include <linux/err.h>
19 #include <linux/slab.h>
20 #include <linux/genhd.h>
23 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
25 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
28 struct class_attribute *class_attr = to_class_attr(attr);
29 struct class_private *cp = to_class(kobj);
33 ret = class_attr->show(cp->class, buf);
37 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
38 const char *buf, size_t count)
40 struct class_attribute *class_attr = to_class_attr(attr);
41 struct class_private *cp = to_class(kobj);
44 if (class_attr->store)
45 ret = class_attr->store(cp->class, buf, count);
49 static void class_release(struct kobject *kobj)
51 struct class_private *cp = to_class(kobj);
52 struct class *class = cp->class;
54 pr_debug("class '%s': release.\n", class->name);
56 if (class->class_release)
57 class->class_release(class);
59 pr_debug("class '%s' does not have a release() function, "
60 "be careful\n", class->name);
63 static struct sysfs_ops class_sysfs_ops = {
64 .show = class_attr_show,
65 .store = class_attr_store,
68 static struct kobj_type class_ktype = {
69 .sysfs_ops = &class_sysfs_ops,
70 .release = class_release,
73 /* Hotplug events for classes go to the class class_subsys */
74 static struct kset *class_kset;
77 int class_create_file(struct class *cls, const struct class_attribute *attr)
81 error = sysfs_create_file(&cls->p->class_subsys.kobj,
88 void class_remove_file(struct class *cls, const struct class_attribute *attr)
91 sysfs_remove_file(&cls->p->class_subsys.kobj, &attr->attr);
94 static struct class *class_get(struct class *cls)
97 kset_get(&cls->p->class_subsys);
101 static void class_put(struct class *cls)
104 kset_put(&cls->p->class_subsys);
107 static int add_class_attrs(struct class *cls)
112 if (cls->class_attrs) {
113 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
114 error = class_create_file(cls, &cls->class_attrs[i]);
123 class_remove_file(cls, &cls->class_attrs[i]);
127 static void remove_class_attrs(struct class *cls)
131 if (cls->class_attrs) {
132 for (i = 0; attr_name(cls->class_attrs[i]); i++)
133 class_remove_file(cls, &cls->class_attrs[i]);
137 int __class_register(struct class *cls, struct lock_class_key *key)
139 struct class_private *cp;
142 pr_debug("device class '%s': registering\n", cls->name);
144 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
147 INIT_LIST_HEAD(&cp->class_devices);
148 INIT_LIST_HEAD(&cp->class_interfaces);
149 kset_init(&cp->class_dirs);
150 init_MUTEX(&cp->class_sem);
151 error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
157 /* set the default /sys/dev directory for devices of this class */
159 cls->dev_kobj = sysfs_dev_char_kobj;
161 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
162 /* let the block class directory show up in the root of sysfs */
163 if (cls != &block_class)
164 cp->class_subsys.kobj.kset = class_kset;
166 cp->class_subsys.kobj.kset = class_kset;
168 cp->class_subsys.kobj.ktype = &class_ktype;
172 error = kset_register(&cp->class_subsys);
177 error = add_class_attrs(class_get(cls));
181 EXPORT_SYMBOL_GPL(__class_register);
183 void class_unregister(struct class *cls)
185 pr_debug("device class '%s': unregistering\n", cls->name);
186 remove_class_attrs(cls);
187 kset_unregister(&cls->p->class_subsys);
190 static void class_create_release(struct class *cls)
192 pr_debug("%s called for %s\n", __func__, cls->name);
197 * class_create - create a struct class structure
198 * @owner: pointer to the module that is to "own" this struct class
199 * @name: pointer to a string for the name of this class.
201 * This is used to create a struct class pointer that can then be used
202 * in calls to device_create().
204 * Note, the pointer created here is to be destroyed when finished by
205 * making a call to class_destroy().
207 struct class *__class_create(struct module *owner, const char *name,
208 struct lock_class_key *key)
213 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
221 cls->class_release = class_create_release;
223 retval = __class_register(cls, key);
231 return ERR_PTR(retval);
233 EXPORT_SYMBOL_GPL(__class_create);
236 * class_destroy - destroys a struct class structure
237 * @cls: pointer to the struct class that is to be destroyed
239 * Note, the pointer to be destroyed must have been created with a call
242 void class_destroy(struct class *cls)
244 if ((cls == NULL) || (IS_ERR(cls)))
247 class_unregister(cls);
250 #ifdef CONFIG_SYSFS_DEPRECATED
251 char *make_class_name(const char *name, struct kobject *kobj)
256 size = strlen(name) + strlen(kobject_name(kobj)) + 2;
258 class_name = kmalloc(size, GFP_KERNEL);
262 strcpy(class_name, name);
263 strcat(class_name, ":");
264 strcat(class_name, kobject_name(kobj));
270 * class_for_each_device - device iterator
271 * @class: the class we're iterating
272 * @start: the device to start with in the list, if any.
273 * @data: data for the callback
274 * @fn: function to be called for each device
276 * Iterate over @class's list of devices, and call @fn for each,
277 * passing it @data. If @start is set, the list iteration will start
278 * there, otherwise if it is NULL, the iteration starts at the
279 * beginning of the list.
281 * We check the return of @fn each time. If it returns anything
282 * other than 0, we break out and return that value.
284 * Note, we hold class->class_sem in this function, so it can not be
285 * re-acquired in @fn, otherwise it will self-deadlocking. For
286 * example, calls to add or remove class members would be verboten.
288 int class_for_each_device(struct class *class, struct device *start,
289 void *data, int (*fn)(struct device *, void *))
296 down(&class->p->class_sem);
297 list_for_each_entry(dev, &class->p->class_devices, node) {
303 dev = get_device(dev);
304 error = fn(dev, data);
309 up(&class->p->class_sem);
313 EXPORT_SYMBOL_GPL(class_for_each_device);
316 * class_find_device - device iterator for locating a particular device
317 * @class: the class we're iterating
318 * @start: Device to begin with
319 * @data: data for the match function
320 * @match: function to check device
322 * This is similar to the class_for_each_dev() function above, but it
323 * returns a reference to a device that is 'found' for later use, as
324 * determined by the @match callback.
326 * The callback should return 0 if the device doesn't match and non-zero
327 * if it does. If the callback returns non-zero, this function will
328 * return to the caller and not iterate over any more devices.
330 * Note, you will need to drop the reference with put_device() after use.
332 * We hold class->class_sem in this function, so it can not be
333 * re-acquired in @match, otherwise it will self-deadlocking. For
334 * example, calls to add or remove class members would be verboten.
336 struct device *class_find_device(struct class *class, struct device *start,
338 int (*match)(struct device *, void *))
346 down(&class->p->class_sem);
347 list_for_each_entry(dev, &class->p->class_devices, node) {
353 dev = get_device(dev);
354 if (match(dev, data)) {
360 up(&class->p->class_sem);
362 return found ? dev : NULL;
364 EXPORT_SYMBOL_GPL(class_find_device);
366 int class_interface_register(struct class_interface *class_intf)
368 struct class *parent;
371 if (!class_intf || !class_intf->class)
374 parent = class_get(class_intf->class);
378 down(&parent->p->class_sem);
379 list_add_tail(&class_intf->node, &parent->p->class_interfaces);
380 if (class_intf->add_dev) {
381 list_for_each_entry(dev, &parent->p->class_devices, node)
382 class_intf->add_dev(dev, class_intf);
384 up(&parent->p->class_sem);
389 void class_interface_unregister(struct class_interface *class_intf)
391 struct class *parent = class_intf->class;
397 down(&parent->p->class_sem);
398 list_del_init(&class_intf->node);
399 if (class_intf->remove_dev) {
400 list_for_each_entry(dev, &parent->p->class_devices, node)
401 class_intf->remove_dev(dev, class_intf);
403 up(&parent->p->class_sem);
408 int __init classes_init(void)
410 class_kset = kset_create_and_add("class", NULL, NULL);
416 EXPORT_SYMBOL_GPL(class_create_file);
417 EXPORT_SYMBOL_GPL(class_remove_file);
418 EXPORT_SYMBOL_GPL(class_unregister);
419 EXPORT_SYMBOL_GPL(class_destroy);
421 EXPORT_SYMBOL_GPL(class_interface_register);
422 EXPORT_SYMBOL_GPL(class_interface_unregister);