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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * class.c - basic device class management
4 *
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2003-2004 Greg Kroah-Hartman
8 * Copyright (c) 2003-2004 IBM Corp.
9 */
10
11#include <linux/device/class.h>
12#include <linux/device.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/string.h>
16#include <linux/kdev_t.h>
17#include <linux/err.h>
18#include <linux/slab.h>
19#include <linux/blkdev.h>
20#include <linux/mutex.h>
21#include "base.h"
22
23/* /sys/class */
24static struct kset *class_kset;
25
26#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
27
28/**
29 * class_to_subsys - Turn a struct class into a struct subsys_private
30 *
31 * @class: pointer to the struct bus_type to look up
32 *
33 * The driver core internals need to work on the subsys_private structure, not
34 * the external struct class pointer. This function walks the list of
35 * registered classes in the system and finds the matching one and returns the
36 * internal struct subsys_private that relates to that class.
37 *
38 * Note, the reference count of the return value is INCREMENTED if it is not
39 * NULL. A call to subsys_put() must be done when finished with the pointer in
40 * order for it to be properly freed.
41 */
42struct subsys_private *class_to_subsys(const struct class *class)
43{
44 struct subsys_private *sp = NULL;
45 struct kobject *kobj;
46
47 if (!class || !class_kset)
48 return NULL;
49
50 spin_lock(&class_kset->list_lock);
51
52 if (list_empty(&class_kset->list))
53 goto done;
54
55 list_for_each_entry(kobj, &class_kset->list, entry) {
56 struct kset *kset = container_of(kobj, struct kset, kobj);
57
58 sp = container_of_const(kset, struct subsys_private, subsys);
59 if (sp->class == class)
60 goto done;
61 }
62 sp = NULL;
63done:
64 sp = subsys_get(sp);
65 spin_unlock(&class_kset->list_lock);
66 return sp;
67}
68
69static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
70 char *buf)
71{
72 struct class_attribute *class_attr = to_class_attr(attr);
73 struct subsys_private *cp = to_subsys_private(kobj);
74 ssize_t ret = -EIO;
75
76 if (class_attr->show)
77 ret = class_attr->show(cp->class, class_attr, buf);
78 return ret;
79}
80
81static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
82 const char *buf, size_t count)
83{
84 struct class_attribute *class_attr = to_class_attr(attr);
85 struct subsys_private *cp = to_subsys_private(kobj);
86 ssize_t ret = -EIO;
87
88 if (class_attr->store)
89 ret = class_attr->store(cp->class, class_attr, buf, count);
90 return ret;
91}
92
93static void class_release(struct kobject *kobj)
94{
95 struct subsys_private *cp = to_subsys_private(kobj);
96 const struct class *class = cp->class;
97
98 pr_debug("class '%s': release.\n", class->name);
99
100 if (class->class_release)
101 class->class_release(class);
102 else
103 pr_debug("class '%s' does not have a release() function, "
104 "be careful\n", class->name);
105
106 lockdep_unregister_key(&cp->lock_key);
107 kfree(cp);
108}
109
110static const struct kobj_ns_type_operations *class_child_ns_type(const struct kobject *kobj)
111{
112 const struct subsys_private *cp = to_subsys_private(kobj);
113 const struct class *class = cp->class;
114
115 return class->ns_type;
116}
117
118static const struct sysfs_ops class_sysfs_ops = {
119 .show = class_attr_show,
120 .store = class_attr_store,
121};
122
123static const struct kobj_type class_ktype = {
124 .sysfs_ops = &class_sysfs_ops,
125 .release = class_release,
126 .child_ns_type = class_child_ns_type,
127};
128
129int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,
130 const void *ns)
131{
132 struct subsys_private *sp = class_to_subsys(cls);
133 int error;
134
135 if (!sp)
136 return -EINVAL;
137
138 error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);
139 subsys_put(sp);
140
141 return error;
142}
143EXPORT_SYMBOL_GPL(class_create_file_ns);
144
145void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,
146 const void *ns)
147{
148 struct subsys_private *sp = class_to_subsys(cls);
149
150 if (!sp)
151 return;
152
153 sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);
154 subsys_put(sp);
155}
156EXPORT_SYMBOL_GPL(class_remove_file_ns);
157
158static struct device *klist_class_to_dev(struct klist_node *n)
159{
160 struct device_private *p = to_device_private_class(n);
161 return p->device;
162}
163
164static void klist_class_dev_get(struct klist_node *n)
165{
166 struct device *dev = klist_class_to_dev(n);
167
168 get_device(dev);
169}
170
171static void klist_class_dev_put(struct klist_node *n)
172{
173 struct device *dev = klist_class_to_dev(n);
174
175 put_device(dev);
176}
177
178int class_register(const struct class *cls)
179{
180 struct subsys_private *cp;
181 struct lock_class_key *key;
182 int error;
183
184 pr_debug("device class '%s': registering\n", cls->name);
185
186 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
187 if (!cp)
188 return -ENOMEM;
189 klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
190 INIT_LIST_HEAD(&cp->interfaces);
191 kset_init(&cp->glue_dirs);
192 key = &cp->lock_key;
193 lockdep_register_key(key);
194 __mutex_init(&cp->mutex, "subsys mutex", key);
195 error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
196 if (error)
197 goto err_out;
198
199 cp->subsys.kobj.kset = class_kset;
200 cp->subsys.kobj.ktype = &class_ktype;
201 cp->class = cls;
202
203 error = kset_register(&cp->subsys);
204 if (error)
205 goto err_out;
206
207 error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);
208 if (error) {
209 kobject_del(&cp->subsys.kobj);
210 kfree_const(cp->subsys.kobj.name);
211 goto err_out;
212 }
213 return 0;
214
215err_out:
216 lockdep_unregister_key(key);
217 kfree(cp);
218 return error;
219}
220EXPORT_SYMBOL_GPL(class_register);
221
222void class_unregister(const struct class *cls)
223{
224 struct subsys_private *sp = class_to_subsys(cls);
225
226 if (!sp)
227 return;
228
229 pr_debug("device class '%s': unregistering\n", cls->name);
230
231 sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);
232 kset_unregister(&sp->subsys);
233 subsys_put(sp);
234}
235EXPORT_SYMBOL_GPL(class_unregister);
236
237static void class_create_release(const struct class *cls)
238{
239 pr_debug("%s called for %s\n", __func__, cls->name);
240 kfree(cls);
241}
242
243/**
244 * class_create - create a struct class structure
245 * @name: pointer to a string for the name of this class.
246 *
247 * This is used to create a struct class pointer that can then be used
248 * in calls to device_create().
249 *
250 * Returns &struct class pointer on success, or ERR_PTR() on error.
251 *
252 * Note, the pointer created here is to be destroyed when finished by
253 * making a call to class_destroy().
254 */
255struct class *class_create(const char *name)
256{
257 struct class *cls;
258 int retval;
259
260 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
261 if (!cls) {
262 retval = -ENOMEM;
263 goto error;
264 }
265
266 cls->name = name;
267 cls->class_release = class_create_release;
268
269 retval = class_register(cls);
270 if (retval)
271 goto error;
272
273 return cls;
274
275error:
276 kfree(cls);
277 return ERR_PTR(retval);
278}
279EXPORT_SYMBOL_GPL(class_create);
280
281/**
282 * class_destroy - destroys a struct class structure
283 * @cls: pointer to the struct class that is to be destroyed
284 *
285 * Note, the pointer to be destroyed must have been created with a call
286 * to class_create().
287 */
288void class_destroy(const struct class *cls)
289{
290 if (IS_ERR_OR_NULL(cls))
291 return;
292
293 class_unregister(cls);
294}
295EXPORT_SYMBOL_GPL(class_destroy);
296
297/**
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
303 *
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
307 * the list.
308 */
309void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
310 const struct device *start, const struct device_type *type)
311{
312 struct subsys_private *sp = class_to_subsys(class);
313 struct klist_node *start_knode = NULL;
314
315 if (!sp)
316 return;
317
318 if (start)
319 start_knode = &start->p->knode_class;
320 klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
321 iter->type = type;
322 iter->sp = sp;
323}
324EXPORT_SYMBOL_GPL(class_dev_iter_init);
325
326/**
327 * class_dev_iter_next - iterate to the next device
328 * @iter: class iterator to proceed
329 *
330 * Proceed @iter to the next device and return it. Returns NULL if
331 * iteration is complete.
332 *
333 * The returned device is referenced and won't be released till
334 * iterator is proceed to the next device or exited. The caller is
335 * free to do whatever it wants to do with the device including
336 * calling back into class code.
337 */
338struct device *class_dev_iter_next(struct class_dev_iter *iter)
339{
340 struct klist_node *knode;
341 struct device *dev;
342
343 while (1) {
344 knode = klist_next(&iter->ki);
345 if (!knode)
346 return NULL;
347 dev = klist_class_to_dev(knode);
348 if (!iter->type || iter->type == dev->type)
349 return dev;
350 }
351}
352EXPORT_SYMBOL_GPL(class_dev_iter_next);
353
354/**
355 * class_dev_iter_exit - finish iteration
356 * @iter: class iterator to finish
357 *
358 * Finish an iteration. Always call this function after iteration is
359 * complete whether the iteration ran till the end or not.
360 */
361void class_dev_iter_exit(struct class_dev_iter *iter)
362{
363 klist_iter_exit(&iter->ki);
364 subsys_put(iter->sp);
365}
366EXPORT_SYMBOL_GPL(class_dev_iter_exit);
367
368/**
369 * class_for_each_device - device iterator
370 * @class: the class we're iterating
371 * @start: the device to start with in the list, if any.
372 * @data: data for the callback
373 * @fn: function to be called for each device
374 *
375 * Iterate over @class's list of devices, and call @fn for each,
376 * passing it @data. If @start is set, the list iteration will start
377 * there, otherwise if it is NULL, the iteration starts at the
378 * beginning of the list.
379 *
380 * We check the return of @fn each time. If it returns anything
381 * other than 0, we break out and return that value.
382 *
383 * @fn is allowed to do anything including calling back into class
384 * code. There's no locking restriction.
385 */
386int class_for_each_device(const struct class *class, const struct device *start,
387 void *data, int (*fn)(struct device *, void *))
388{
389 struct subsys_private *sp = class_to_subsys(class);
390 struct class_dev_iter iter;
391 struct device *dev;
392 int error = 0;
393
394 if (!class)
395 return -EINVAL;
396 if (!sp) {
397 WARN(1, "%s called for class '%s' before it was initialized",
398 __func__, class->name);
399 return -EINVAL;
400 }
401
402 class_dev_iter_init(&iter, class, start, NULL);
403 while ((dev = class_dev_iter_next(&iter))) {
404 error = fn(dev, data);
405 if (error)
406 break;
407 }
408 class_dev_iter_exit(&iter);
409 subsys_put(sp);
410
411 return error;
412}
413EXPORT_SYMBOL_GPL(class_for_each_device);
414
415/**
416 * class_find_device - device iterator for locating a particular device
417 * @class: the class we're iterating
418 * @start: Device to begin with
419 * @data: data for the match function
420 * @match: function to check device
421 *
422 * This is similar to the class_for_each_dev() function above, but it
423 * returns a reference to a device that is 'found' for later use, as
424 * determined by the @match callback.
425 *
426 * The callback should return 0 if the device doesn't match and non-zero
427 * if it does. If the callback returns non-zero, this function will
428 * return to the caller and not iterate over any more devices.
429 *
430 * Note, you will need to drop the reference with put_device() after use.
431 *
432 * @match is allowed to do anything including calling back into class
433 * code. There's no locking restriction.
434 */
435struct device *class_find_device(const struct class *class, const struct device *start,
436 const void *data,
437 int (*match)(struct device *, const void *))
438{
439 struct subsys_private *sp = class_to_subsys(class);
440 struct class_dev_iter iter;
441 struct device *dev;
442
443 if (!class)
444 return NULL;
445 if (!sp) {
446 WARN(1, "%s called for class '%s' before it was initialized",
447 __func__, class->name);
448 return NULL;
449 }
450
451 class_dev_iter_init(&iter, class, start, NULL);
452 while ((dev = class_dev_iter_next(&iter))) {
453 if (match(dev, data)) {
454 get_device(dev);
455 break;
456 }
457 }
458 class_dev_iter_exit(&iter);
459 subsys_put(sp);
460
461 return dev;
462}
463EXPORT_SYMBOL_GPL(class_find_device);
464
465int class_interface_register(struct class_interface *class_intf)
466{
467 struct subsys_private *sp;
468 const struct class *parent;
469 struct class_dev_iter iter;
470 struct device *dev;
471
472 if (!class_intf || !class_intf->class)
473 return -ENODEV;
474
475 parent = class_intf->class;
476 sp = class_to_subsys(parent);
477 if (!sp)
478 return -EINVAL;
479
480 /*
481 * Reference in sp is now incremented and will be dropped when
482 * the interface is removed in the call to class_interface_unregister()
483 */
484
485 mutex_lock(&sp->mutex);
486 list_add_tail(&class_intf->node, &sp->interfaces);
487 if (class_intf->add_dev) {
488 class_dev_iter_init(&iter, parent, NULL, NULL);
489 while ((dev = class_dev_iter_next(&iter)))
490 class_intf->add_dev(dev);
491 class_dev_iter_exit(&iter);
492 }
493 mutex_unlock(&sp->mutex);
494
495 return 0;
496}
497EXPORT_SYMBOL_GPL(class_interface_register);
498
499void class_interface_unregister(struct class_interface *class_intf)
500{
501 struct subsys_private *sp;
502 const struct class *parent = class_intf->class;
503 struct class_dev_iter iter;
504 struct device *dev;
505
506 if (!parent)
507 return;
508
509 sp = class_to_subsys(parent);
510 if (!sp)
511 return;
512
513 mutex_lock(&sp->mutex);
514 list_del_init(&class_intf->node);
515 if (class_intf->remove_dev) {
516 class_dev_iter_init(&iter, parent, NULL, NULL);
517 while ((dev = class_dev_iter_next(&iter)))
518 class_intf->remove_dev(dev);
519 class_dev_iter_exit(&iter);
520 }
521 mutex_unlock(&sp->mutex);
522
523 /*
524 * Decrement the reference count twice, once for the class_to_subsys()
525 * call in the start of this function, and the second one from the
526 * reference increment in class_interface_register()
527 */
528 subsys_put(sp);
529 subsys_put(sp);
530}
531EXPORT_SYMBOL_GPL(class_interface_unregister);
532
533ssize_t show_class_attr_string(const struct class *class,
534 const struct class_attribute *attr, char *buf)
535{
536 struct class_attribute_string *cs;
537
538 cs = container_of(attr, struct class_attribute_string, attr);
539 return sysfs_emit(buf, "%s\n", cs->str);
540}
541
542EXPORT_SYMBOL_GPL(show_class_attr_string);
543
544struct class_compat {
545 struct kobject *kobj;
546};
547
548/**
549 * class_compat_register - register a compatibility class
550 * @name: the name of the class
551 *
552 * Compatibility class are meant as a temporary user-space compatibility
553 * workaround when converting a family of class devices to a bus devices.
554 */
555struct class_compat *class_compat_register(const char *name)
556{
557 struct class_compat *cls;
558
559 cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
560 if (!cls)
561 return NULL;
562 cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
563 if (!cls->kobj) {
564 kfree(cls);
565 return NULL;
566 }
567 return cls;
568}
569EXPORT_SYMBOL_GPL(class_compat_register);
570
571/**
572 * class_compat_unregister - unregister a compatibility class
573 * @cls: the class to unregister
574 */
575void class_compat_unregister(struct class_compat *cls)
576{
577 kobject_put(cls->kobj);
578 kfree(cls);
579}
580EXPORT_SYMBOL_GPL(class_compat_unregister);
581
582/**
583 * class_compat_create_link - create a compatibility class device link to
584 * a bus device
585 * @cls: the compatibility class
586 * @dev: the target bus device
587 * @device_link: an optional device to which a "device" link should be created
588 */
589int class_compat_create_link(struct class_compat *cls, struct device *dev,
590 struct device *device_link)
591{
592 int error;
593
594 error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
595 if (error)
596 return error;
597
598 /*
599 * Optionally add a "device" link (typically to the parent), as a
600 * class device would have one and we want to provide as much
601 * backwards compatibility as possible.
602 */
603 if (device_link) {
604 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
605 "device");
606 if (error)
607 sysfs_remove_link(cls->kobj, dev_name(dev));
608 }
609
610 return error;
611}
612EXPORT_SYMBOL_GPL(class_compat_create_link);
613
614/**
615 * class_compat_remove_link - remove a compatibility class device link to
616 * a bus device
617 * @cls: the compatibility class
618 * @dev: the target bus device
619 * @device_link: an optional device to which a "device" link was previously
620 * created
621 */
622void class_compat_remove_link(struct class_compat *cls, struct device *dev,
623 struct device *device_link)
624{
625 if (device_link)
626 sysfs_remove_link(&dev->kobj, "device");
627 sysfs_remove_link(cls->kobj, dev_name(dev));
628}
629EXPORT_SYMBOL_GPL(class_compat_remove_link);
630
631/**
632 * class_is_registered - determine if at this moment in time, a class is
633 * registered in the driver core or not.
634 * @class: the class to check
635 *
636 * Returns a boolean to state if the class is registered in the driver core
637 * or not. Note that the value could switch right after this call is made,
638 * so only use this in places where you "know" it is safe to do so (usually
639 * to determine if the specific class has been registered yet or not).
640 *
641 * Be careful in using this.
642 */
643bool class_is_registered(const struct class *class)
644{
645 struct subsys_private *sp = class_to_subsys(class);
646 bool is_initialized = false;
647
648 if (sp) {
649 is_initialized = true;
650 subsys_put(sp);
651 }
652 return is_initialized;
653}
654EXPORT_SYMBOL_GPL(class_is_registered);
655
656int __init classes_init(void)
657{
658 class_kset = kset_create_and_add("class", NULL, NULL);
659 if (!class_kset)
660 return -ENOMEM;
661 return 0;
662}
1/*
2 * class.c - basic device class management
3 *
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.
8 *
9 * This file is released under the GPLv2
10 *
11 */
12
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>
22#include "base.h"
23
24#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
25
26static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
27 char *buf)
28{
29 struct class_attribute *class_attr = to_class_attr(attr);
30 struct subsys_private *cp = to_subsys_private(kobj);
31 ssize_t ret = -EIO;
32
33 if (class_attr->show)
34 ret = class_attr->show(cp->class, class_attr, buf);
35 return ret;
36}
37
38static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
39 const char *buf, size_t count)
40{
41 struct class_attribute *class_attr = to_class_attr(attr);
42 struct subsys_private *cp = to_subsys_private(kobj);
43 ssize_t ret = -EIO;
44
45 if (class_attr->store)
46 ret = class_attr->store(cp->class, class_attr, buf, count);
47 return ret;
48}
49
50static void class_release(struct kobject *kobj)
51{
52 struct subsys_private *cp = to_subsys_private(kobj);
53 struct class *class = cp->class;
54
55 pr_debug("class '%s': release.\n", class->name);
56
57 if (class->class_release)
58 class->class_release(class);
59 else
60 pr_debug("class '%s' does not have a release() function, "
61 "be careful\n", class->name);
62
63 kfree(cp);
64}
65
66static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
67{
68 struct subsys_private *cp = to_subsys_private(kobj);
69 struct class *class = cp->class;
70
71 return class->ns_type;
72}
73
74static const struct sysfs_ops class_sysfs_ops = {
75 .show = class_attr_show,
76 .store = class_attr_store,
77};
78
79static struct kobj_type class_ktype = {
80 .sysfs_ops = &class_sysfs_ops,
81 .release = class_release,
82 .child_ns_type = class_child_ns_type,
83};
84
85/* Hotplug events for classes go to the class subsys */
86static struct kset *class_kset;
87
88
89int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
90 const void *ns)
91{
92 int error;
93
94 if (cls)
95 error = sysfs_create_file_ns(&cls->p->subsys.kobj,
96 &attr->attr, ns);
97 else
98 error = -EINVAL;
99 return error;
100}
101
102void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
103 const void *ns)
104{
105 if (cls)
106 sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
107}
108
109static struct class *class_get(struct class *cls)
110{
111 if (cls)
112 kset_get(&cls->p->subsys);
113 return cls;
114}
115
116static void class_put(struct class *cls)
117{
118 if (cls)
119 kset_put(&cls->p->subsys);
120}
121
122static int add_class_attrs(struct class *cls)
123{
124 int i;
125 int error = 0;
126
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]);
130 if (error)
131 goto error;
132 }
133 }
134done:
135 return error;
136error:
137 while (--i >= 0)
138 class_remove_file(cls, &cls->class_attrs[i]);
139 goto done;
140}
141
142static void remove_class_attrs(struct class *cls)
143{
144 int i;
145
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]);
149 }
150}
151
152static void klist_class_dev_get(struct klist_node *n)
153{
154 struct device *dev = container_of(n, struct device, knode_class);
155
156 get_device(dev);
157}
158
159static void klist_class_dev_put(struct klist_node *n)
160{
161 struct device *dev = container_of(n, struct device, knode_class);
162
163 put_device(dev);
164}
165
166int __class_register(struct class *cls, struct lock_class_key *key)
167{
168 struct subsys_private *cp;
169 int error;
170
171 pr_debug("device class '%s': registering\n", cls->name);
172
173 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
174 if (!cp)
175 return -ENOMEM;
176 klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
177 INIT_LIST_HEAD(&cp->interfaces);
178 kset_init(&cp->glue_dirs);
179 __mutex_init(&cp->mutex, "subsys mutex", key);
180 error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
181 if (error) {
182 kfree(cp);
183 return error;
184 }
185
186 /* set the default /sys/dev directory for devices of this class */
187 if (!cls->dev_kobj)
188 cls->dev_kobj = sysfs_dev_char_kobj;
189
190#if defined(CONFIG_BLOCK)
191 /* let the block class directory show up in the root of sysfs */
192 if (!sysfs_deprecated || cls != &block_class)
193 cp->subsys.kobj.kset = class_kset;
194#else
195 cp->subsys.kobj.kset = class_kset;
196#endif
197 cp->subsys.kobj.ktype = &class_ktype;
198 cp->class = cls;
199 cls->p = cp;
200
201 error = kset_register(&cp->subsys);
202 if (error) {
203 kfree(cp);
204 return error;
205 }
206 error = add_class_attrs(class_get(cls));
207 class_put(cls);
208 return error;
209}
210EXPORT_SYMBOL_GPL(__class_register);
211
212void class_unregister(struct class *cls)
213{
214 pr_debug("device class '%s': unregistering\n", cls->name);
215 remove_class_attrs(cls);
216 kset_unregister(&cls->p->subsys);
217}
218
219static void class_create_release(struct class *cls)
220{
221 pr_debug("%s called for %s\n", __func__, cls->name);
222 kfree(cls);
223}
224
225/**
226 * class_create - create a struct class structure
227 * @owner: pointer to the module that is to "own" this struct class
228 * @name: pointer to a string for the name of this class.
229 * @key: the lock_class_key for this class; used by mutex lock debugging
230 *
231 * This is used to create a struct class pointer that can then be used
232 * in calls to device_create().
233 *
234 * Returns &struct class pointer on success, or ERR_PTR() on error.
235 *
236 * Note, the pointer created here is to be destroyed when finished by
237 * making a call to class_destroy().
238 */
239struct class *__class_create(struct module *owner, const char *name,
240 struct lock_class_key *key)
241{
242 struct class *cls;
243 int retval;
244
245 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
246 if (!cls) {
247 retval = -ENOMEM;
248 goto error;
249 }
250
251 cls->name = name;
252 cls->owner = owner;
253 cls->class_release = class_create_release;
254
255 retval = __class_register(cls, key);
256 if (retval)
257 goto error;
258
259 return cls;
260
261error:
262 kfree(cls);
263 return ERR_PTR(retval);
264}
265EXPORT_SYMBOL_GPL(__class_create);
266
267/**
268 * class_destroy - destroys a struct class structure
269 * @cls: pointer to the struct class that is to be destroyed
270 *
271 * Note, the pointer to be destroyed must have been created with a call
272 * to class_create().
273 */
274void class_destroy(struct class *cls)
275{
276 if ((cls == NULL) || (IS_ERR(cls)))
277 return;
278
279 class_unregister(cls);
280}
281
282/**
283 * class_dev_iter_init - initialize class device iterator
284 * @iter: class iterator to initialize
285 * @class: the class we wanna iterate over
286 * @start: the device to start iterating from, if any
287 * @type: device_type of the devices to iterate over, NULL for all
288 *
289 * Initialize class iterator @iter such that it iterates over devices
290 * of @class. If @start is set, the list iteration will start there,
291 * otherwise if it is NULL, the iteration starts at the beginning of
292 * the list.
293 */
294void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
295 struct device *start, const struct device_type *type)
296{
297 struct klist_node *start_knode = NULL;
298
299 if (start)
300 start_knode = &start->knode_class;
301 klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
302 iter->type = type;
303}
304EXPORT_SYMBOL_GPL(class_dev_iter_init);
305
306/**
307 * class_dev_iter_next - iterate to the next device
308 * @iter: class iterator to proceed
309 *
310 * Proceed @iter to the next device and return it. Returns NULL if
311 * iteration is complete.
312 *
313 * The returned device is referenced and won't be released till
314 * iterator is proceed to the next device or exited. The caller is
315 * free to do whatever it wants to do with the device including
316 * calling back into class code.
317 */
318struct device *class_dev_iter_next(struct class_dev_iter *iter)
319{
320 struct klist_node *knode;
321 struct device *dev;
322
323 while (1) {
324 knode = klist_next(&iter->ki);
325 if (!knode)
326 return NULL;
327 dev = container_of(knode, struct device, knode_class);
328 if (!iter->type || iter->type == dev->type)
329 return dev;
330 }
331}
332EXPORT_SYMBOL_GPL(class_dev_iter_next);
333
334/**
335 * class_dev_iter_exit - finish iteration
336 * @iter: class iterator to finish
337 *
338 * Finish an iteration. Always call this function after iteration is
339 * complete whether the iteration ran till the end or not.
340 */
341void class_dev_iter_exit(struct class_dev_iter *iter)
342{
343 klist_iter_exit(&iter->ki);
344}
345EXPORT_SYMBOL_GPL(class_dev_iter_exit);
346
347/**
348 * class_for_each_device - device iterator
349 * @class: the class we're iterating
350 * @start: the device to start with in the list, if any.
351 * @data: data for the callback
352 * @fn: function to be called for each device
353 *
354 * Iterate over @class's list of devices, and call @fn for each,
355 * passing it @data. If @start is set, the list iteration will start
356 * there, otherwise if it is NULL, the iteration starts at the
357 * beginning of the list.
358 *
359 * We check the return of @fn each time. If it returns anything
360 * other than 0, we break out and return that value.
361 *
362 * @fn is allowed to do anything including calling back into class
363 * code. There's no locking restriction.
364 */
365int class_for_each_device(struct class *class, struct device *start,
366 void *data, int (*fn)(struct device *, void *))
367{
368 struct class_dev_iter iter;
369 struct device *dev;
370 int error = 0;
371
372 if (!class)
373 return -EINVAL;
374 if (!class->p) {
375 WARN(1, "%s called for class '%s' before it was initialized",
376 __func__, class->name);
377 return -EINVAL;
378 }
379
380 class_dev_iter_init(&iter, class, start, NULL);
381 while ((dev = class_dev_iter_next(&iter))) {
382 error = fn(dev, data);
383 if (error)
384 break;
385 }
386 class_dev_iter_exit(&iter);
387
388 return error;
389}
390EXPORT_SYMBOL_GPL(class_for_each_device);
391
392/**
393 * class_find_device - device iterator for locating a particular device
394 * @class: the class we're iterating
395 * @start: Device to begin with
396 * @data: data for the match function
397 * @match: function to check device
398 *
399 * This is similar to the class_for_each_dev() function above, but it
400 * returns a reference to a device that is 'found' for later use, as
401 * determined by the @match callback.
402 *
403 * The callback should return 0 if the device doesn't match and non-zero
404 * if it does. If the callback returns non-zero, this function will
405 * return to the caller and not iterate over any more devices.
406 *
407 * Note, you will need to drop the reference with put_device() after use.
408 *
409 * @match is allowed to do anything including calling back into class
410 * code. There's no locking restriction.
411 */
412struct device *class_find_device(struct class *class, struct device *start,
413 const void *data,
414 int (*match)(struct device *, const void *))
415{
416 struct class_dev_iter iter;
417 struct device *dev;
418
419 if (!class)
420 return NULL;
421 if (!class->p) {
422 WARN(1, "%s called for class '%s' before it was initialized",
423 __func__, class->name);
424 return NULL;
425 }
426
427 class_dev_iter_init(&iter, class, start, NULL);
428 while ((dev = class_dev_iter_next(&iter))) {
429 if (match(dev, data)) {
430 get_device(dev);
431 break;
432 }
433 }
434 class_dev_iter_exit(&iter);
435
436 return dev;
437}
438EXPORT_SYMBOL_GPL(class_find_device);
439
440int class_interface_register(struct class_interface *class_intf)
441{
442 struct class *parent;
443 struct class_dev_iter iter;
444 struct device *dev;
445
446 if (!class_intf || !class_intf->class)
447 return -ENODEV;
448
449 parent = class_get(class_intf->class);
450 if (!parent)
451 return -EINVAL;
452
453 mutex_lock(&parent->p->mutex);
454 list_add_tail(&class_intf->node, &parent->p->interfaces);
455 if (class_intf->add_dev) {
456 class_dev_iter_init(&iter, parent, NULL, NULL);
457 while ((dev = class_dev_iter_next(&iter)))
458 class_intf->add_dev(dev, class_intf);
459 class_dev_iter_exit(&iter);
460 }
461 mutex_unlock(&parent->p->mutex);
462
463 return 0;
464}
465
466void class_interface_unregister(struct class_interface *class_intf)
467{
468 struct class *parent = class_intf->class;
469 struct class_dev_iter iter;
470 struct device *dev;
471
472 if (!parent)
473 return;
474
475 mutex_lock(&parent->p->mutex);
476 list_del_init(&class_intf->node);
477 if (class_intf->remove_dev) {
478 class_dev_iter_init(&iter, parent, NULL, NULL);
479 while ((dev = class_dev_iter_next(&iter)))
480 class_intf->remove_dev(dev, class_intf);
481 class_dev_iter_exit(&iter);
482 }
483 mutex_unlock(&parent->p->mutex);
484
485 class_put(parent);
486}
487
488ssize_t show_class_attr_string(struct class *class,
489 struct class_attribute *attr, char *buf)
490{
491 struct class_attribute_string *cs;
492
493 cs = container_of(attr, struct class_attribute_string, attr);
494 return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
495}
496
497EXPORT_SYMBOL_GPL(show_class_attr_string);
498
499struct class_compat {
500 struct kobject *kobj;
501};
502
503/**
504 * class_compat_register - register a compatibility class
505 * @name: the name of the class
506 *
507 * Compatibility class are meant as a temporary user-space compatibility
508 * workaround when converting a family of class devices to a bus devices.
509 */
510struct class_compat *class_compat_register(const char *name)
511{
512 struct class_compat *cls;
513
514 cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
515 if (!cls)
516 return NULL;
517 cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
518 if (!cls->kobj) {
519 kfree(cls);
520 return NULL;
521 }
522 return cls;
523}
524EXPORT_SYMBOL_GPL(class_compat_register);
525
526/**
527 * class_compat_unregister - unregister a compatibility class
528 * @cls: the class to unregister
529 */
530void class_compat_unregister(struct class_compat *cls)
531{
532 kobject_put(cls->kobj);
533 kfree(cls);
534}
535EXPORT_SYMBOL_GPL(class_compat_unregister);
536
537/**
538 * class_compat_create_link - create a compatibility class device link to
539 * a bus device
540 * @cls: the compatibility class
541 * @dev: the target bus device
542 * @device_link: an optional device to which a "device" link should be created
543 */
544int class_compat_create_link(struct class_compat *cls, struct device *dev,
545 struct device *device_link)
546{
547 int error;
548
549 error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
550 if (error)
551 return error;
552
553 /*
554 * Optionally add a "device" link (typically to the parent), as a
555 * class device would have one and we want to provide as much
556 * backwards compatibility as possible.
557 */
558 if (device_link) {
559 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
560 "device");
561 if (error)
562 sysfs_remove_link(cls->kobj, dev_name(dev));
563 }
564
565 return error;
566}
567EXPORT_SYMBOL_GPL(class_compat_create_link);
568
569/**
570 * class_compat_remove_link - remove a compatibility class device link to
571 * a bus device
572 * @cls: the compatibility class
573 * @dev: the target bus device
574 * @device_link: an optional device to which a "device" link was previously
575 * created
576 */
577void class_compat_remove_link(struct class_compat *cls, struct device *dev,
578 struct device *device_link)
579{
580 if (device_link)
581 sysfs_remove_link(&dev->kobj, "device");
582 sysfs_remove_link(cls->kobj, dev_name(dev));
583}
584EXPORT_SYMBOL_GPL(class_compat_remove_link);
585
586int __init classes_init(void)
587{
588 class_kset = kset_create_and_add("class", NULL, NULL);
589 if (!class_kset)
590 return -ENOMEM;
591 return 0;
592}
593
594EXPORT_SYMBOL_GPL(class_create_file_ns);
595EXPORT_SYMBOL_GPL(class_remove_file_ns);
596EXPORT_SYMBOL_GPL(class_unregister);
597EXPORT_SYMBOL_GPL(class_destroy);
598
599EXPORT_SYMBOL_GPL(class_interface_register);
600EXPORT_SYMBOL_GPL(class_interface_unregister);