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 subsys_private
*cp
= to_subsys_private(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 subsys_private
*cp
= to_subsys_private(kobj
);
45 if (class_attr
->store
)
46 ret
= class_attr
->store(cp
->class, class_attr
, buf
, count
);
50 static const void *class_attr_namespace(struct kobject
*kobj
,
51 const struct attribute
*attr
)
53 struct class_attribute
*class_attr
= to_class_attr(attr
);
54 struct subsys_private
*cp
= to_subsys_private(kobj
);
55 const void *ns
= NULL
;
57 if (class_attr
->namespace)
58 ns
= class_attr
->namespace(cp
->class, class_attr
);
62 static void class_release(struct kobject
*kobj
)
64 struct subsys_private
*cp
= to_subsys_private(kobj
);
65 struct class *class = cp
->class;
67 pr_debug("class '%s': release.\n", class->name
);
69 if (class->class_release
)
70 class->class_release(class);
72 pr_debug("class '%s' does not have a release() function, "
73 "be careful\n", class->name
);
78 static const struct kobj_ns_type_operations
*class_child_ns_type(struct kobject
*kobj
)
80 struct subsys_private
*cp
= to_subsys_private(kobj
);
81 struct class *class = cp
->class;
83 return class->ns_type
;
86 static const struct sysfs_ops class_sysfs_ops
= {
87 .show
= class_attr_show
,
88 .store
= class_attr_store
,
89 .namespace = class_attr_namespace
,
92 static struct kobj_type class_ktype
= {
93 .sysfs_ops
= &class_sysfs_ops
,
94 .release
= class_release
,
95 .child_ns_type
= class_child_ns_type
,
98 /* Hotplug events for classes go to the class subsys */
99 static struct kset
*class_kset
;
102 int class_create_file(struct class *cls
, const struct class_attribute
*attr
)
106 error
= sysfs_create_file(&cls
->p
->subsys
.kobj
,
113 void class_remove_file(struct class *cls
, const struct class_attribute
*attr
)
116 sysfs_remove_file(&cls
->p
->subsys
.kobj
, &attr
->attr
);
119 static struct class *class_get(struct class *cls
)
122 kset_get(&cls
->p
->subsys
);
126 static void class_put(struct class *cls
)
129 kset_put(&cls
->p
->subsys
);
132 static int add_class_attrs(struct class *cls
)
137 if (cls
->class_attrs
) {
138 for (i
= 0; cls
->class_attrs
[i
].attr
.name
; i
++) {
139 error
= class_create_file(cls
, &cls
->class_attrs
[i
]);
148 class_remove_file(cls
, &cls
->class_attrs
[i
]);
152 static void remove_class_attrs(struct class *cls
)
156 if (cls
->class_attrs
) {
157 for (i
= 0; cls
->class_attrs
[i
].attr
.name
; i
++)
158 class_remove_file(cls
, &cls
->class_attrs
[i
]);
162 static void klist_class_dev_get(struct klist_node
*n
)
164 struct device
*dev
= container_of(n
, struct device
, knode_class
);
169 static void klist_class_dev_put(struct klist_node
*n
)
171 struct device
*dev
= container_of(n
, struct device
, knode_class
);
176 int __class_register(struct class *cls
, struct lock_class_key
*key
)
178 struct subsys_private
*cp
;
181 pr_debug("device class '%s': registering\n", cls
->name
);
183 cp
= kzalloc(sizeof(*cp
), GFP_KERNEL
);
186 klist_init(&cp
->klist_devices
, klist_class_dev_get
, klist_class_dev_put
);
187 INIT_LIST_HEAD(&cp
->interfaces
);
188 kset_init(&cp
->glue_dirs
);
189 __mutex_init(&cp
->mutex
, "subsys mutex", key
);
190 error
= kobject_set_name(&cp
->subsys
.kobj
, "%s", cls
->name
);
196 /* set the default /sys/dev directory for devices of this class */
198 cls
->dev_kobj
= sysfs_dev_char_kobj
;
200 #if defined(CONFIG_BLOCK)
201 /* let the block class directory show up in the root of sysfs */
202 if (!sysfs_deprecated
|| cls
!= &block_class
)
203 cp
->subsys
.kobj
.kset
= class_kset
;
205 cp
->subsys
.kobj
.kset
= class_kset
;
207 cp
->subsys
.kobj
.ktype
= &class_ktype
;
211 error
= kset_register(&cp
->subsys
);
216 error
= add_class_attrs(class_get(cls
));
220 EXPORT_SYMBOL_GPL(__class_register
);
222 void class_unregister(struct class *cls
)
224 pr_debug("device class '%s': unregistering\n", cls
->name
);
225 remove_class_attrs(cls
);
226 kset_unregister(&cls
->p
->subsys
);
229 static void class_create_release(struct class *cls
)
231 pr_debug("%s called for %s\n", __func__
, cls
->name
);
236 * class_create - create a struct class structure
237 * @owner: pointer to the module that is to "own" this struct class
238 * @name: pointer to a string for the name of this class.
239 * @key: the lock_class_key for this class; used by mutex lock debugging
241 * This is used to create a struct class pointer that can then be used
242 * in calls to device_create().
244 * Returns &struct class pointer on success, or ERR_PTR() on error.
246 * Note, the pointer created here is to be destroyed when finished by
247 * making a call to class_destroy().
249 struct class *__class_create(struct module
*owner
, const char *name
,
250 struct lock_class_key
*key
)
255 cls
= kzalloc(sizeof(*cls
), GFP_KERNEL
);
263 cls
->class_release
= class_create_release
;
265 retval
= __class_register(cls
, key
);
273 return ERR_PTR(retval
);
275 EXPORT_SYMBOL_GPL(__class_create
);
278 * class_destroy - destroys a struct class structure
279 * @cls: pointer to the struct class that is to be destroyed
281 * Note, the pointer to be destroyed must have been created with a call
284 void class_destroy(struct class *cls
)
286 if ((cls
== NULL
) || (IS_ERR(cls
)))
289 class_unregister(cls
);
293 * class_dev_iter_init - initialize class device iterator
294 * @iter: class iterator to initialize
295 * @class: the class we wanna iterate over
296 * @start: the device to start iterating from, if any
297 * @type: device_type of the devices to iterate over, NULL for all
299 * Initialize class iterator @iter such that it iterates over devices
300 * of @class. If @start is set, the list iteration will start there,
301 * otherwise if it is NULL, the iteration starts at the beginning of
304 void class_dev_iter_init(struct class_dev_iter
*iter
, struct class *class,
305 struct device
*start
, const struct device_type
*type
)
307 struct klist_node
*start_knode
= NULL
;
310 start_knode
= &start
->knode_class
;
311 klist_iter_init_node(&class->p
->klist_devices
, &iter
->ki
, start_knode
);
314 EXPORT_SYMBOL_GPL(class_dev_iter_init
);
317 * class_dev_iter_next - iterate to the next device
318 * @iter: class iterator to proceed
320 * Proceed @iter to the next device and return it. Returns NULL if
321 * iteration is complete.
323 * The returned device is referenced and won't be released till
324 * iterator is proceed to the next device or exited. The caller is
325 * free to do whatever it wants to do with the device including
326 * calling back into class code.
328 struct device
*class_dev_iter_next(struct class_dev_iter
*iter
)
330 struct klist_node
*knode
;
334 knode
= klist_next(&iter
->ki
);
337 dev
= container_of(knode
, struct device
, knode_class
);
338 if (!iter
->type
|| iter
->type
== dev
->type
)
342 EXPORT_SYMBOL_GPL(class_dev_iter_next
);
345 * class_dev_iter_exit - finish iteration
346 * @iter: class iterator to finish
348 * Finish an iteration. Always call this function after iteration is
349 * complete whether the iteration ran till the end or not.
351 void class_dev_iter_exit(struct class_dev_iter
*iter
)
353 klist_iter_exit(&iter
->ki
);
355 EXPORT_SYMBOL_GPL(class_dev_iter_exit
);
358 * class_for_each_device - device iterator
359 * @class: the class we're iterating
360 * @start: the device to start with in the list, if any.
361 * @data: data for the callback
362 * @fn: function to be called for each device
364 * Iterate over @class's list of devices, and call @fn for each,
365 * passing it @data. If @start is set, the list iteration will start
366 * there, otherwise if it is NULL, the iteration starts at the
367 * beginning of the list.
369 * We check the return of @fn each time. If it returns anything
370 * other than 0, we break out and return that value.
372 * @fn is allowed to do anything including calling back into class
373 * code. There's no locking restriction.
375 int class_for_each_device(struct class *class, struct device
*start
,
376 void *data
, int (*fn
)(struct device
*, void *))
378 struct class_dev_iter iter
;
385 WARN(1, "%s called for class '%s' before it was initialized",
386 __func__
, class->name
);
390 class_dev_iter_init(&iter
, class, start
, NULL
);
391 while ((dev
= class_dev_iter_next(&iter
))) {
392 error
= fn(dev
, data
);
396 class_dev_iter_exit(&iter
);
400 EXPORT_SYMBOL_GPL(class_for_each_device
);
403 * class_find_device - device iterator for locating a particular device
404 * @class: the class we're iterating
405 * @start: Device to begin with
406 * @data: data for the match function
407 * @match: function to check device
409 * This is similar to the class_for_each_dev() function above, but it
410 * returns a reference to a device that is 'found' for later use, as
411 * determined by the @match callback.
413 * The callback should return 0 if the device doesn't match and non-zero
414 * if it does. If the callback returns non-zero, this function will
415 * return to the caller and not iterate over any more devices.
417 * Note, you will need to drop the reference with put_device() after use.
419 * @fn is allowed to do anything including calling back into class
420 * code. There's no locking restriction.
422 struct device
*class_find_device(struct class *class, struct device
*start
,
424 int (*match
)(struct device
*, const void *))
426 struct class_dev_iter iter
;
432 WARN(1, "%s called for class '%s' before it was initialized",
433 __func__
, class->name
);
437 class_dev_iter_init(&iter
, class, start
, NULL
);
438 while ((dev
= class_dev_iter_next(&iter
))) {
439 if (match(dev
, data
)) {
444 class_dev_iter_exit(&iter
);
448 EXPORT_SYMBOL_GPL(class_find_device
);
450 int class_interface_register(struct class_interface
*class_intf
)
452 struct class *parent
;
453 struct class_dev_iter iter
;
456 if (!class_intf
|| !class_intf
->class)
459 parent
= class_get(class_intf
->class);
463 mutex_lock(&parent
->p
->mutex
);
464 list_add_tail(&class_intf
->node
, &parent
->p
->interfaces
);
465 if (class_intf
->add_dev
) {
466 class_dev_iter_init(&iter
, parent
, NULL
, NULL
);
467 while ((dev
= class_dev_iter_next(&iter
)))
468 class_intf
->add_dev(dev
, class_intf
);
469 class_dev_iter_exit(&iter
);
471 mutex_unlock(&parent
->p
->mutex
);
476 void class_interface_unregister(struct class_interface
*class_intf
)
478 struct class *parent
= class_intf
->class;
479 struct class_dev_iter iter
;
485 mutex_lock(&parent
->p
->mutex
);
486 list_del_init(&class_intf
->node
);
487 if (class_intf
->remove_dev
) {
488 class_dev_iter_init(&iter
, parent
, NULL
, NULL
);
489 while ((dev
= class_dev_iter_next(&iter
)))
490 class_intf
->remove_dev(dev
, class_intf
);
491 class_dev_iter_exit(&iter
);
493 mutex_unlock(&parent
->p
->mutex
);
498 ssize_t
show_class_attr_string(struct class *class,
499 struct class_attribute
*attr
, char *buf
)
501 struct class_attribute_string
*cs
;
502 cs
= container_of(attr
, struct class_attribute_string
, attr
);
503 return snprintf(buf
, PAGE_SIZE
, "%s\n", cs
->str
);
506 EXPORT_SYMBOL_GPL(show_class_attr_string
);
508 struct class_compat
{
509 struct kobject
*kobj
;
513 * class_compat_register - register a compatibility class
514 * @name: the name of the class
516 * Compatibility class are meant as a temporary user-space compatibility
517 * workaround when converting a family of class devices to a bus devices.
519 struct class_compat
*class_compat_register(const char *name
)
521 struct class_compat
*cls
;
523 cls
= kmalloc(sizeof(struct class_compat
), GFP_KERNEL
);
526 cls
->kobj
= kobject_create_and_add(name
, &class_kset
->kobj
);
533 EXPORT_SYMBOL_GPL(class_compat_register
);
536 * class_compat_unregister - unregister a compatibility class
537 * @cls: the class to unregister
539 void class_compat_unregister(struct class_compat
*cls
)
541 kobject_put(cls
->kobj
);
544 EXPORT_SYMBOL_GPL(class_compat_unregister
);
547 * class_compat_create_link - create a compatibility class device link to
549 * @cls: the compatibility class
550 * @dev: the target bus device
551 * @device_link: an optional device to which a "device" link should be created
553 int class_compat_create_link(struct class_compat
*cls
, struct device
*dev
,
554 struct device
*device_link
)
558 error
= sysfs_create_link(cls
->kobj
, &dev
->kobj
, dev_name(dev
));
563 * Optionally add a "device" link (typically to the parent), as a
564 * class device would have one and we want to provide as much
565 * backwards compatibility as possible.
568 error
= sysfs_create_link(&dev
->kobj
, &device_link
->kobj
,
571 sysfs_remove_link(cls
->kobj
, dev_name(dev
));
576 EXPORT_SYMBOL_GPL(class_compat_create_link
);
579 * class_compat_remove_link - remove a compatibility class device link to
581 * @cls: the compatibility class
582 * @dev: the target bus device
583 * @device_link: an optional device to which a "device" link was previously
586 void class_compat_remove_link(struct class_compat
*cls
, struct device
*dev
,
587 struct device
*device_link
)
590 sysfs_remove_link(&dev
->kobj
, "device");
591 sysfs_remove_link(cls
->kobj
, dev_name(dev
));
593 EXPORT_SYMBOL_GPL(class_compat_remove_link
);
595 int __init
classes_init(void)
597 class_kset
= kset_create_and_add("class", NULL
, NULL
);
603 EXPORT_SYMBOL_GPL(class_create_file
);
604 EXPORT_SYMBOL_GPL(class_remove_file
);
605 EXPORT_SYMBOL_GPL(class_unregister
);
606 EXPORT_SYMBOL_GPL(class_destroy
);
608 EXPORT_SYMBOL_GPL(class_interface_register
);
609 EXPORT_SYMBOL_GPL(class_interface_unregister
);