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 void class_release(struct kobject
*kobj
)
52 struct subsys_private
*cp
= to_subsys_private(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 subsys_private
*cp
= to_subsys_private(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 subsys */
86 static struct kset
*class_kset
;
89 int class_create_file_ns(struct class *cls
, const struct class_attribute
*attr
,
95 error
= sysfs_create_file_ns(&cls
->p
->subsys
.kobj
,
102 void class_remove_file_ns(struct class *cls
, const struct class_attribute
*attr
,
106 sysfs_remove_file_ns(&cls
->p
->subsys
.kobj
, &attr
->attr
, ns
);
109 static struct class *class_get(struct class *cls
)
112 kset_get(&cls
->p
->subsys
);
116 static void class_put(struct class *cls
)
119 kset_put(&cls
->p
->subsys
);
122 static int add_class_attrs(struct class *cls
)
127 if (cls
->class_attrs
) {
128 for (i
= 0; cls
->class_attrs
[i
].attr
.name
; i
++) {
129 error
= class_create_file(cls
, &cls
->class_attrs
[i
]);
138 class_remove_file(cls
, &cls
->class_attrs
[i
]);
142 static void remove_class_attrs(struct class *cls
)
146 if (cls
->class_attrs
) {
147 for (i
= 0; cls
->class_attrs
[i
].attr
.name
; i
++)
148 class_remove_file(cls
, &cls
->class_attrs
[i
]);
152 static void klist_class_dev_get(struct klist_node
*n
)
154 struct device
*dev
= container_of(n
, struct device
, knode_class
);
159 static void klist_class_dev_put(struct klist_node
*n
)
161 struct device
*dev
= container_of(n
, struct device
, knode_class
);
166 static int class_add_groups(struct class *cls
,
167 const struct attribute_group
**groups
)
169 return sysfs_create_groups(&cls
->p
->subsys
.kobj
, groups
);
172 static void class_remove_groups(struct class *cls
,
173 const struct attribute_group
**groups
)
175 return sysfs_remove_groups(&cls
->p
->subsys
.kobj
, groups
);
178 int __class_register(struct class *cls
, struct lock_class_key
*key
)
180 struct subsys_private
*cp
;
183 pr_debug("device class '%s': registering\n", cls
->name
);
185 cp
= kzalloc(sizeof(*cp
), GFP_KERNEL
);
188 klist_init(&cp
->klist_devices
, klist_class_dev_get
, klist_class_dev_put
);
189 INIT_LIST_HEAD(&cp
->interfaces
);
190 kset_init(&cp
->glue_dirs
);
191 __mutex_init(&cp
->mutex
, "subsys mutex", key
);
192 error
= kobject_set_name(&cp
->subsys
.kobj
, "%s", cls
->name
);
198 /* set the default /sys/dev directory for devices of this class */
200 cls
->dev_kobj
= sysfs_dev_char_kobj
;
202 #if defined(CONFIG_BLOCK)
203 /* let the block class directory show up in the root of sysfs */
204 if (!sysfs_deprecated
|| cls
!= &block_class
)
205 cp
->subsys
.kobj
.kset
= class_kset
;
207 cp
->subsys
.kobj
.kset
= class_kset
;
209 cp
->subsys
.kobj
.ktype
= &class_ktype
;
213 error
= kset_register(&cp
->subsys
);
218 error
= class_add_groups(class_get(cls
), cls
->class_groups
);
220 error
= add_class_attrs(class_get(cls
));
224 EXPORT_SYMBOL_GPL(__class_register
);
226 void class_unregister(struct class *cls
)
228 pr_debug("device class '%s': unregistering\n", cls
->name
);
229 remove_class_attrs(cls
);
230 class_remove_groups(cls
, cls
->class_groups
);
231 kset_unregister(&cls
->p
->subsys
);
234 static void class_create_release(struct class *cls
)
236 pr_debug("%s called for %s\n", __func__
, cls
->name
);
241 * class_create - create a struct class structure
242 * @owner: pointer to the module that is to "own" this struct class
243 * @name: pointer to a string for the name of this class.
244 * @key: the lock_class_key for this class; used by mutex lock debugging
246 * This is used to create a struct class pointer that can then be used
247 * in calls to device_create().
249 * Returns &struct class pointer on success, or ERR_PTR() on error.
251 * Note, the pointer created here is to be destroyed when finished by
252 * making a call to class_destroy().
254 struct class *__class_create(struct module
*owner
, const char *name
,
255 struct lock_class_key
*key
)
260 cls
= kzalloc(sizeof(*cls
), GFP_KERNEL
);
268 cls
->class_release
= class_create_release
;
270 retval
= __class_register(cls
, key
);
278 return ERR_PTR(retval
);
280 EXPORT_SYMBOL_GPL(__class_create
);
283 * class_destroy - destroys a struct class structure
284 * @cls: pointer to the struct class that is to be destroyed
286 * Note, the pointer to be destroyed must have been created with a call
289 void class_destroy(struct class *cls
)
291 if ((cls
== NULL
) || (IS_ERR(cls
)))
294 class_unregister(cls
);
298 * class_dev_iter_init - initialize class device iterator
299 * @iter: class iterator to initialize
300 * @class: the class we wanna iterate over
301 * @start: the device to start iterating from, if any
302 * @type: device_type of the devices to iterate over, NULL for all
304 * Initialize class iterator @iter such that it iterates over devices
305 * of @class. If @start is set, the list iteration will start there,
306 * otherwise if it is NULL, the iteration starts at the beginning of
309 void class_dev_iter_init(struct class_dev_iter
*iter
, struct class *class,
310 struct device
*start
, const struct device_type
*type
)
312 struct klist_node
*start_knode
= NULL
;
315 start_knode
= &start
->knode_class
;
316 klist_iter_init_node(&class->p
->klist_devices
, &iter
->ki
, start_knode
);
319 EXPORT_SYMBOL_GPL(class_dev_iter_init
);
322 * class_dev_iter_next - iterate to the next device
323 * @iter: class iterator to proceed
325 * Proceed @iter to the next device and return it. Returns NULL if
326 * iteration is complete.
328 * The returned device is referenced and won't be released till
329 * iterator is proceed to the next device or exited. The caller is
330 * free to do whatever it wants to do with the device including
331 * calling back into class code.
333 struct device
*class_dev_iter_next(struct class_dev_iter
*iter
)
335 struct klist_node
*knode
;
339 knode
= klist_next(&iter
->ki
);
342 dev
= container_of(knode
, struct device
, knode_class
);
343 if (!iter
->type
|| iter
->type
== dev
->type
)
347 EXPORT_SYMBOL_GPL(class_dev_iter_next
);
350 * class_dev_iter_exit - finish iteration
351 * @iter: class iterator to finish
353 * Finish an iteration. Always call this function after iteration is
354 * complete whether the iteration ran till the end or not.
356 void class_dev_iter_exit(struct class_dev_iter
*iter
)
358 klist_iter_exit(&iter
->ki
);
360 EXPORT_SYMBOL_GPL(class_dev_iter_exit
);
363 * class_for_each_device - device iterator
364 * @class: the class we're iterating
365 * @start: the device to start with in the list, if any.
366 * @data: data for the callback
367 * @fn: function to be called for each device
369 * Iterate over @class's list of devices, and call @fn for each,
370 * passing it @data. If @start is set, the list iteration will start
371 * there, otherwise if it is NULL, the iteration starts at the
372 * beginning of the list.
374 * We check the return of @fn each time. If it returns anything
375 * other than 0, we break out and return that value.
377 * @fn is allowed to do anything including calling back into class
378 * code. There's no locking restriction.
380 int class_for_each_device(struct class *class, struct device
*start
,
381 void *data
, int (*fn
)(struct device
*, void *))
383 struct class_dev_iter iter
;
390 WARN(1, "%s called for class '%s' before it was initialized",
391 __func__
, class->name
);
395 class_dev_iter_init(&iter
, class, start
, NULL
);
396 while ((dev
= class_dev_iter_next(&iter
))) {
397 error
= fn(dev
, data
);
401 class_dev_iter_exit(&iter
);
405 EXPORT_SYMBOL_GPL(class_for_each_device
);
408 * class_find_device - device iterator for locating a particular device
409 * @class: the class we're iterating
410 * @start: Device to begin with
411 * @data: data for the match function
412 * @match: function to check device
414 * This is similar to the class_for_each_dev() function above, but it
415 * returns a reference to a device that is 'found' for later use, as
416 * determined by the @match callback.
418 * The callback should return 0 if the device doesn't match and non-zero
419 * if it does. If the callback returns non-zero, this function will
420 * return to the caller and not iterate over any more devices.
422 * Note, you will need to drop the reference with put_device() after use.
424 * @match is allowed to do anything including calling back into class
425 * code. There's no locking restriction.
427 struct device
*class_find_device(struct class *class, struct device
*start
,
429 int (*match
)(struct device
*, const void *))
431 struct class_dev_iter iter
;
437 WARN(1, "%s called for class '%s' before it was initialized",
438 __func__
, class->name
);
442 class_dev_iter_init(&iter
, class, start
, NULL
);
443 while ((dev
= class_dev_iter_next(&iter
))) {
444 if (match(dev
, data
)) {
449 class_dev_iter_exit(&iter
);
453 EXPORT_SYMBOL_GPL(class_find_device
);
455 int class_interface_register(struct class_interface
*class_intf
)
457 struct class *parent
;
458 struct class_dev_iter iter
;
461 if (!class_intf
|| !class_intf
->class)
464 parent
= class_get(class_intf
->class);
468 mutex_lock(&parent
->p
->mutex
);
469 list_add_tail(&class_intf
->node
, &parent
->p
->interfaces
);
470 if (class_intf
->add_dev
) {
471 class_dev_iter_init(&iter
, parent
, NULL
, NULL
);
472 while ((dev
= class_dev_iter_next(&iter
)))
473 class_intf
->add_dev(dev
, class_intf
);
474 class_dev_iter_exit(&iter
);
476 mutex_unlock(&parent
->p
->mutex
);
481 void class_interface_unregister(struct class_interface
*class_intf
)
483 struct class *parent
= class_intf
->class;
484 struct class_dev_iter iter
;
490 mutex_lock(&parent
->p
->mutex
);
491 list_del_init(&class_intf
->node
);
492 if (class_intf
->remove_dev
) {
493 class_dev_iter_init(&iter
, parent
, NULL
, NULL
);
494 while ((dev
= class_dev_iter_next(&iter
)))
495 class_intf
->remove_dev(dev
, class_intf
);
496 class_dev_iter_exit(&iter
);
498 mutex_unlock(&parent
->p
->mutex
);
503 ssize_t
show_class_attr_string(struct class *class,
504 struct class_attribute
*attr
, char *buf
)
506 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_ns
);
610 EXPORT_SYMBOL_GPL(class_remove_file_ns
);
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
);