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>
21 #include <linux/mutex.h>
24 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
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_private *cp = to_class(kobj);
34 ret = class_attr->show(cp->class, class_attr, 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_private *cp = to_class(kobj);
45 if (class_attr->store)
46 ret = class_attr->store(cp->class, class_attr, buf, count);
50 static void class_release(struct kobject *kobj)
52 struct class_private *cp = to_class(kobj);
53 struct class *class = cp->class;
55 pr_debug("class '%s': release.\n", class->name);
57 if (class->class_release)
58 class->class_release(class);
60 pr_debug("class '%s' does not have a release() function, "
61 "be careful\n", class->name);
66 static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
68 struct class_private *cp = to_class(kobj);
69 struct class *class = cp->class;
71 return class->ns_type;
74 static const struct sysfs_ops class_sysfs_ops = {
75 .show = class_attr_show,
76 .store = class_attr_store,
79 static struct kobj_type class_ktype = {
80 .sysfs_ops = &class_sysfs_ops,
81 .release = class_release,
82 .child_ns_type = class_child_ns_type,
85 /* Hotplug events for classes go to the class class_subsys */
86 static struct kset *class_kset;
89 int class_create_file(struct class *cls, const struct class_attribute *attr)
93 error = sysfs_create_file(&cls->p->class_subsys.kobj,
100 void class_remove_file(struct class *cls, const struct class_attribute *attr)
103 sysfs_remove_file(&cls->p->class_subsys.kobj, &attr->attr);
106 static struct class *class_get(struct class *cls)
109 kset_get(&cls->p->class_subsys);
113 static void class_put(struct class *cls)
116 kset_put(&cls->p->class_subsys);
119 static int add_class_attrs(struct class *cls)
124 if (cls->class_attrs) {
125 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
126 error = class_create_file(cls, &cls->class_attrs[i]);
135 class_remove_file(cls, &cls->class_attrs[i]);
139 static void remove_class_attrs(struct class *cls)
143 if (cls->class_attrs) {
144 for (i = 0; attr_name(cls->class_attrs[i]); i++)
145 class_remove_file(cls, &cls->class_attrs[i]);
149 static void klist_class_dev_get(struct klist_node *n)
151 struct device *dev = container_of(n, struct device, knode_class);
156 static void klist_class_dev_put(struct klist_node *n)
158 struct device *dev = container_of(n, struct device, knode_class);
163 int __class_register(struct class *cls, struct lock_class_key *key)
165 struct class_private *cp;
168 pr_debug("device class '%s': registering\n", cls->name);
170 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
173 klist_init(&cp->class_devices, klist_class_dev_get, klist_class_dev_put);
174 INIT_LIST_HEAD(&cp->class_interfaces);
175 kset_init(&cp->class_dirs);
176 __mutex_init(&cp->class_mutex, "struct class mutex", key);
177 error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
183 /* set the default /sys/dev directory for devices of this class */
185 cls->dev_kobj = sysfs_dev_char_kobj;
187 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
188 /* let the block class directory show up in the root of sysfs */
189 if (cls != &block_class)
190 cp->class_subsys.kobj.kset = class_kset;
192 cp->class_subsys.kobj.kset = class_kset;
194 cp->class_subsys.kobj.ktype = &class_ktype;
198 error = kset_register(&cp->class_subsys);
203 error = add_class_attrs(class_get(cls));
207 EXPORT_SYMBOL_GPL(__class_register);
209 void class_unregister(struct class *cls)
211 pr_debug("device class '%s': unregistering\n", cls->name);
212 remove_class_attrs(cls);
213 kset_unregister(&cls->p->class_subsys);
216 static void class_create_release(struct class *cls)
218 pr_debug("%s called for %s\n", __func__, cls->name);
223 * class_create - create a struct class structure
224 * @owner: pointer to the module that is to "own" this struct class
225 * @name: pointer to a string for the name of this class.
226 * @key: the lock_class_key for this class; used by mutex lock debugging
228 * This is used to create a struct class pointer that can then be used
229 * in calls to device_create().
231 * Returns &struct class pointer on success, or ERR_PTR() on error.
233 * Note, the pointer created here is to be destroyed when finished by
234 * making a call to class_destroy().
236 struct class *__class_create(struct module *owner, const char *name,
237 struct lock_class_key *key)
242 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
250 cls->class_release = class_create_release;
252 retval = __class_register(cls, key);
260 return ERR_PTR(retval);
262 EXPORT_SYMBOL_GPL(__class_create);
265 * class_destroy - destroys a struct class structure
266 * @cls: pointer to the struct class that is to be destroyed
268 * Note, the pointer to be destroyed must have been created with a call
271 void class_destroy(struct class *cls)
273 if ((cls == NULL) || (IS_ERR(cls)))
276 class_unregister(cls);
279 #ifdef CONFIG_SYSFS_DEPRECATED
280 char *make_class_name(const char *name, struct kobject *kobj)
285 size = strlen(name) + strlen(kobject_name(kobj)) + 2;
287 class_name = kmalloc(size, GFP_KERNEL);
291 strcpy(class_name, name);
292 strcat(class_name, ":");
293 strcat(class_name, kobject_name(kobj));
299 * class_dev_iter_init - initialize class device iterator
300 * @iter: class iterator to initialize
301 * @class: the class we wanna iterate over
302 * @start: the device to start iterating from, if any
303 * @type: device_type of the devices to iterate over, NULL for all
305 * Initialize class iterator @iter such that it iterates over devices
306 * of @class. If @start is set, the list iteration will start there,
307 * otherwise if it is NULL, the iteration starts at the beginning of
310 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
311 struct device *start, const struct device_type *type)
313 struct klist_node *start_knode = NULL;
316 start_knode = &start->knode_class;
317 klist_iter_init_node(&class->p->class_devices, &iter->ki, start_knode);
320 EXPORT_SYMBOL_GPL(class_dev_iter_init);
323 * class_dev_iter_next - iterate to the next device
324 * @iter: class iterator to proceed
326 * Proceed @iter to the next device and return it. Returns NULL if
327 * iteration is complete.
329 * The returned device is referenced and won't be released till
330 * iterator is proceed to the next device or exited. The caller is
331 * free to do whatever it wants to do with the device including
332 * calling back into class code.
334 struct device *class_dev_iter_next(struct class_dev_iter *iter)
336 struct klist_node *knode;
340 knode = klist_next(&iter->ki);
343 dev = container_of(knode, struct device, knode_class);
344 if (!iter->type || iter->type == dev->type)
348 EXPORT_SYMBOL_GPL(class_dev_iter_next);
351 * class_dev_iter_exit - finish iteration
352 * @iter: class iterator to finish
354 * Finish an iteration. Always call this function after iteration is
355 * complete whether the iteration ran till the end or not.
357 void class_dev_iter_exit(struct class_dev_iter *iter)
359 klist_iter_exit(&iter->ki);
361 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
364 * class_for_each_device - device iterator
365 * @class: the class we're iterating
366 * @start: the device to start with in the list, if any.
367 * @data: data for the callback
368 * @fn: function to be called for each device
370 * Iterate over @class's list of devices, and call @fn for each,
371 * passing it @data. If @start is set, the list iteration will start
372 * there, otherwise if it is NULL, the iteration starts at the
373 * beginning of the list.
375 * We check the return of @fn each time. If it returns anything
376 * other than 0, we break out and return that value.
378 * @fn is allowed to do anything including calling back into class
379 * code. There's no locking restriction.
381 int class_for_each_device(struct class *class, struct device *start,
382 void *data, int (*fn)(struct device *, void *))
384 struct class_dev_iter iter;
391 WARN(1, "%s called for class '%s' before it was initialized",
392 __func__, class->name);
396 class_dev_iter_init(&iter, class, start, NULL);
397 while ((dev = class_dev_iter_next(&iter))) {
398 error = fn(dev, data);
402 class_dev_iter_exit(&iter);
406 EXPORT_SYMBOL_GPL(class_for_each_device);
409 * class_find_device - device iterator for locating a particular device
410 * @class: the class we're iterating
411 * @start: Device to begin with
412 * @data: data for the match function
413 * @match: function to check device
415 * This is similar to the class_for_each_dev() function above, but it
416 * returns a reference to a device that is 'found' for later use, as
417 * determined by the @match callback.
419 * The callback should return 0 if the device doesn't match and non-zero
420 * if it does. If the callback returns non-zero, this function will
421 * return to the caller and not iterate over any more devices.
423 * Note, you will need to drop the reference with put_device() after use.
425 * @fn is allowed to do anything including calling back into class
426 * code. There's no locking restriction.
428 struct device *class_find_device(struct class *class, struct device *start,
430 int (*match)(struct device *, void *))
432 struct class_dev_iter iter;
438 WARN(1, "%s called for class '%s' before it was initialized",
439 __func__, class->name);
443 class_dev_iter_init(&iter, class, start, NULL);
444 while ((dev = class_dev_iter_next(&iter))) {
445 if (match(dev, data)) {
450 class_dev_iter_exit(&iter);
454 EXPORT_SYMBOL_GPL(class_find_device);
456 int class_interface_register(struct class_interface *class_intf)
458 struct class *parent;
459 struct class_dev_iter iter;
462 if (!class_intf || !class_intf->class)
465 parent = class_get(class_intf->class);
469 mutex_lock(&parent->p->class_mutex);
470 list_add_tail(&class_intf->node, &parent->p->class_interfaces);
471 if (class_intf->add_dev) {
472 class_dev_iter_init(&iter, parent, NULL, NULL);
473 while ((dev = class_dev_iter_next(&iter)))
474 class_intf->add_dev(dev, class_intf);
475 class_dev_iter_exit(&iter);
477 mutex_unlock(&parent->p->class_mutex);
482 void class_interface_unregister(struct class_interface *class_intf)
484 struct class *parent = class_intf->class;
485 struct class_dev_iter iter;
491 mutex_lock(&parent->p->class_mutex);
492 list_del_init(&class_intf->node);
493 if (class_intf->remove_dev) {
494 class_dev_iter_init(&iter, parent, NULL, NULL);
495 while ((dev = class_dev_iter_next(&iter)))
496 class_intf->remove_dev(dev, class_intf);
497 class_dev_iter_exit(&iter);
499 mutex_unlock(&parent->p->class_mutex);
504 ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
507 struct class_attribute_string *cs;
508 cs = container_of(attr, struct class_attribute_string, attr);
509 return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
512 EXPORT_SYMBOL_GPL(show_class_attr_string);
514 struct class_compat {
515 struct kobject *kobj;
519 * class_compat_register - register a compatibility class
520 * @name: the name of the class
522 * Compatibility class are meant as a temporary user-space compatibility
523 * workaround when converting a family of class devices to a bus devices.
525 struct class_compat *class_compat_register(const char *name)
527 struct class_compat *cls;
529 cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
532 cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
539 EXPORT_SYMBOL_GPL(class_compat_register);
542 * class_compat_unregister - unregister a compatibility class
543 * @cls: the class to unregister
545 void class_compat_unregister(struct class_compat *cls)
547 kobject_put(cls->kobj);
550 EXPORT_SYMBOL_GPL(class_compat_unregister);
553 * class_compat_create_link - create a compatibility class device link to
555 * @cls: the compatibility class
556 * @dev: the target bus device
557 * @device_link: an optional device to which a "device" link should be created
559 int class_compat_create_link(struct class_compat *cls, struct device *dev,
560 struct device *device_link)
564 error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
569 * Optionally add a "device" link (typically to the parent), as a
570 * class device would have one and we want to provide as much
571 * backwards compatibility as possible.
574 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
577 sysfs_remove_link(cls->kobj, dev_name(dev));
582 EXPORT_SYMBOL_GPL(class_compat_create_link);
585 * class_compat_remove_link - remove a compatibility class device link to
587 * @cls: the compatibility class
588 * @dev: the target bus device
589 * @device_link: an optional device to which a "device" link was previously
592 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
593 struct device *device_link)
596 sysfs_remove_link(&dev->kobj, "device");
597 sysfs_remove_link(cls->kobj, dev_name(dev));
599 EXPORT_SYMBOL_GPL(class_compat_remove_link);
601 int __init classes_init(void)
603 class_kset = kset_create_and_add("class", NULL, NULL);
609 EXPORT_SYMBOL_GPL(class_create_file);
610 EXPORT_SYMBOL_GPL(class_remove_file);
611 EXPORT_SYMBOL_GPL(class_unregister);
612 EXPORT_SYMBOL_GPL(class_destroy);
614 EXPORT_SYMBOL_GPL(class_interface_register);
615 EXPORT_SYMBOL_GPL(class_interface_unregister);