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