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)
24 #define to_class(obj) container_of(obj, struct class, subsys.kobj)
26 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
29 struct class_attribute *class_attr = to_class_attr(attr);
30 struct class *dc = to_class(kobj);
34 ret = class_attr->show(dc, buf);
38 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
39 const char *buf, size_t count)
41 struct class_attribute *class_attr = to_class_attr(attr);
42 struct class *dc = to_class(kobj);
45 if (class_attr->store)
46 ret = class_attr->store(dc, buf, count);
50 static void class_release(struct kobject *kobj)
52 struct class *class = to_class(kobj);
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_obj 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->subsys.kobj, &attr->attr);
87 void class_remove_file(struct class *cls, const struct class_attribute *attr)
90 sysfs_remove_file(&cls->subsys.kobj, &attr->attr);
93 static struct class *class_get(struct class *cls)
96 return container_of(kset_get(&cls->subsys),
97 struct class, subsys);
101 static void class_put(struct class *cls)
104 kset_put(&cls->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)
141 pr_debug("device class '%s': registering\n", cls->name);
143 INIT_LIST_HEAD(&cls->devices);
144 INIT_LIST_HEAD(&cls->interfaces);
145 kset_init(&cls->class_dirs);
146 init_MUTEX(&cls->sem);
147 error = kobject_set_name(&cls->subsys.kobj, "%s", cls->name);
151 /* set the default /sys/dev directory for devices of this class */
153 cls->dev_kobj = sysfs_dev_char_kobj;
155 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
156 /* let the block class directory show up in the root of sysfs */
157 if (cls != &block_class)
158 cls->subsys.kobj.kset = class_kset;
160 cls->subsys.kobj.kset = class_kset;
162 cls->subsys.kobj.ktype = &class_ktype;
164 error = kset_register(&cls->subsys);
166 error = add_class_attrs(class_get(cls));
172 void class_unregister(struct class *cls)
174 pr_debug("device class '%s': unregistering\n", cls->name);
175 remove_class_attrs(cls);
176 kset_unregister(&cls->subsys);
179 static void class_create_release(struct class *cls)
181 pr_debug("%s called for %s\n", __func__, cls->name);
186 * class_create - create a struct class structure
187 * @owner: pointer to the module that is to "own" this struct class
188 * @name: pointer to a string for the name of this class.
190 * This is used to create a struct class pointer that can then be used
191 * in calls to device_create().
193 * Note, the pointer created here is to be destroyed when finished by
194 * making a call to class_destroy().
196 struct class *class_create(struct module *owner, const char *name)
201 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
209 cls->class_release = class_create_release;
211 retval = class_register(cls);
219 return ERR_PTR(retval);
223 * class_destroy - destroys a struct class structure
224 * @cls: pointer to the struct class that is to be destroyed
226 * Note, the pointer to be destroyed must have been created with a call
229 void class_destroy(struct class *cls)
231 if ((cls == NULL) || (IS_ERR(cls)))
234 class_unregister(cls);
237 #ifdef CONFIG_SYSFS_DEPRECATED
238 char *make_class_name(const char *name, struct kobject *kobj)
243 size = strlen(name) + strlen(kobject_name(kobj)) + 2;
245 class_name = kmalloc(size, GFP_KERNEL);
249 strcpy(class_name, name);
250 strcat(class_name, ":");
251 strcat(class_name, kobject_name(kobj));
257 * class_for_each_device - device iterator
258 * @class: the class we're iterating
259 * @start: the device to start with in the list, if any.
260 * @data: data for the callback
261 * @fn: function to be called for each device
263 * Iterate over @class's list of devices, and call @fn for each,
264 * passing it @data. If @start is set, the list iteration will start
265 * there, otherwise if it is NULL, the iteration starts at the
266 * beginning of the list.
268 * We check the return of @fn each time. If it returns anything
269 * other than 0, we break out and return that value.
271 * Note, we hold class->sem in this function, so it can not be
272 * re-acquired in @fn, otherwise it will self-deadlocking. For
273 * example, calls to add or remove class members would be verboten.
275 int class_for_each_device(struct class *class, struct device *start,
276 void *data, int (*fn)(struct device *, void *))
284 list_for_each_entry(dev, &class->devices, node) {
290 dev = get_device(dev);
291 error = fn(dev, data);
300 EXPORT_SYMBOL_GPL(class_for_each_device);
303 * class_find_device - device iterator for locating a particular device
304 * @class: the class we're iterating
305 * @data: data for the match function
306 * @match: function to check device
308 * This is similar to the class_for_each_dev() function above, but it
309 * returns a reference to a device that is 'found' for later use, as
310 * determined by the @match callback.
312 * The callback should return 0 if the device doesn't match and non-zero
313 * if it does. If the callback returns non-zero, this function will
314 * return to the caller and not iterate over any more devices.
316 * Note, you will need to drop the reference with put_device() after use.
318 * We hold class->sem in this function, so it can not be
319 * re-acquired in @match, otherwise it will self-deadlocking. For
320 * example, calls to add or remove class members would be verboten.
322 struct device *class_find_device(struct class *class, void *data,
323 int (*match)(struct device *, void *))
332 list_for_each_entry(dev, &class->devices, node) {
333 dev = get_device(dev);
335 if (match(dev, data)) {
345 return found ? dev : NULL;
347 EXPORT_SYMBOL_GPL(class_find_device);
349 int class_interface_register(struct class_interface *class_intf)
351 struct class *parent;
354 if (!class_intf || !class_intf->class)
357 parent = class_get(class_intf->class);
362 list_add_tail(&class_intf->node, &parent->interfaces);
363 if (class_intf->add_dev) {
364 list_for_each_entry(dev, &parent->devices, node)
365 class_intf->add_dev(dev, class_intf);
372 void class_interface_unregister(struct class_interface *class_intf)
374 struct class *parent = class_intf->class;
381 list_del_init(&class_intf->node);
382 if (class_intf->remove_dev) {
383 list_for_each_entry(dev, &parent->devices, node)
384 class_intf->remove_dev(dev, class_intf);
391 int __init classes_init(void)
393 class_kset = kset_create_and_add("class", NULL, NULL);
399 EXPORT_SYMBOL_GPL(class_create_file);
400 EXPORT_SYMBOL_GPL(class_remove_file);
401 EXPORT_SYMBOL_GPL(class_register);
402 EXPORT_SYMBOL_GPL(class_unregister);
403 EXPORT_SYMBOL_GPL(class_create);
404 EXPORT_SYMBOL_GPL(class_destroy);
406 EXPORT_SYMBOL_GPL(class_interface_register);
407 EXPORT_SYMBOL_GPL(class_interface_unregister);