Line data Source code
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/genhd.h>
20 : #include <linux/mutex.h>
21 : #include "base.h"
22 :
23 : #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
24 :
25 0 : static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
26 : char *buf)
27 : {
28 0 : struct class_attribute *class_attr = to_class_attr(attr);
29 0 : struct subsys_private *cp = to_subsys_private(kobj);
30 0 : ssize_t ret = -EIO;
31 :
32 0 : if (class_attr->show)
33 0 : ret = class_attr->show(cp->class, class_attr, buf);
34 0 : return ret;
35 : }
36 :
37 0 : static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
38 : const char *buf, size_t count)
39 : {
40 0 : struct class_attribute *class_attr = to_class_attr(attr);
41 0 : struct subsys_private *cp = to_subsys_private(kobj);
42 0 : ssize_t ret = -EIO;
43 :
44 0 : if (class_attr->store)
45 0 : ret = class_attr->store(cp->class, class_attr, buf, count);
46 0 : return ret;
47 : }
48 :
49 0 : static void class_release(struct kobject *kobj)
50 : {
51 0 : struct subsys_private *cp = to_subsys_private(kobj);
52 0 : struct class *class = cp->class;
53 :
54 0 : pr_debug("class '%s': release.\n", class->name);
55 :
56 0 : if (class->class_release)
57 0 : class->class_release(class);
58 : else
59 : pr_debug("class '%s' does not have a release() function, "
60 : "be careful\n", class->name);
61 :
62 0 : kfree(cp);
63 0 : }
64 :
65 15 : static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
66 : {
67 15 : struct subsys_private *cp = to_subsys_private(kobj);
68 15 : struct class *class = cp->class;
69 :
70 15 : return class->ns_type;
71 : }
72 :
73 : static const struct sysfs_ops class_sysfs_ops = {
74 : .show = class_attr_show,
75 : .store = class_attr_store,
76 : };
77 :
78 : static struct kobj_type class_ktype = {
79 : .sysfs_ops = &class_sysfs_ops,
80 : .release = class_release,
81 : .child_ns_type = class_child_ns_type,
82 : };
83 :
84 : /* Hotplug events for classes go to the class subsys */
85 : static struct kset *class_kset;
86 :
87 :
88 0 : int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
89 : const void *ns)
90 : {
91 0 : int error;
92 :
93 0 : if (cls)
94 0 : error = sysfs_create_file_ns(&cls->p->subsys.kobj,
95 : &attr->attr, ns);
96 : else
97 : error = -EINVAL;
98 0 : return error;
99 : }
100 :
101 0 : void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
102 : const void *ns)
103 : {
104 0 : if (cls)
105 0 : sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
106 0 : }
107 :
108 17 : static struct class *class_get(struct class *cls)
109 : {
110 17 : if (cls)
111 15 : kset_get(&cls->p->subsys);
112 17 : return cls;
113 : }
114 :
115 15 : static void class_put(struct class *cls)
116 : {
117 15 : if (cls)
118 15 : kset_put(&cls->p->subsys);
119 : }
120 :
121 9499 : static struct device *klist_class_to_dev(struct klist_node *n)
122 : {
123 9499 : struct device_private *p = to_device_private_class(n);
124 9499 : return p->device;
125 : }
126 :
127 123 : static void klist_class_dev_get(struct klist_node *n)
128 : {
129 123 : struct device *dev = klist_class_to_dev(n);
130 :
131 123 : get_device(dev);
132 123 : }
133 :
134 0 : static void klist_class_dev_put(struct klist_node *n)
135 : {
136 0 : struct device *dev = klist_class_to_dev(n);
137 :
138 0 : put_device(dev);
139 0 : }
140 :
141 15 : static int class_add_groups(struct class *cls,
142 : const struct attribute_group **groups)
143 : {
144 15 : return sysfs_create_groups(&cls->p->subsys.kobj, groups);
145 : }
146 :
147 0 : static void class_remove_groups(struct class *cls,
148 : const struct attribute_group **groups)
149 : {
150 0 : return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
151 : }
152 :
153 15 : int __class_register(struct class *cls, struct lock_class_key *key)
154 : {
155 15 : struct subsys_private *cp;
156 15 : int error;
157 :
158 15 : pr_debug("device class '%s': registering\n", cls->name);
159 :
160 15 : cp = kzalloc(sizeof(*cp), GFP_KERNEL);
161 15 : if (!cp)
162 : return -ENOMEM;
163 15 : klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
164 15 : INIT_LIST_HEAD(&cp->interfaces);
165 15 : kset_init(&cp->glue_dirs);
166 15 : __mutex_init(&cp->mutex, "subsys mutex", key);
167 15 : error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
168 15 : if (error) {
169 0 : kfree(cp);
170 0 : return error;
171 : }
172 :
173 : /* set the default /sys/dev directory for devices of this class */
174 15 : if (!cls->dev_kobj)
175 14 : cls->dev_kobj = sysfs_dev_char_kobj;
176 :
177 : #if defined(CONFIG_BLOCK)
178 : /* let the block class directory show up in the root of sysfs */
179 15 : if (!sysfs_deprecated || cls != &block_class)
180 15 : cp->subsys.kobj.kset = class_kset;
181 : #else
182 : cp->subsys.kobj.kset = class_kset;
183 : #endif
184 15 : cp->subsys.kobj.ktype = &class_ktype;
185 15 : cp->class = cls;
186 15 : cls->p = cp;
187 :
188 15 : error = kset_register(&cp->subsys);
189 15 : if (error) {
190 0 : kfree(cp);
191 0 : return error;
192 : }
193 30 : error = class_add_groups(class_get(cls), cls->class_groups);
194 15 : class_put(cls);
195 : return error;
196 : }
197 : EXPORT_SYMBOL_GPL(__class_register);
198 :
199 0 : void class_unregister(struct class *cls)
200 : {
201 0 : pr_debug("device class '%s': unregistering\n", cls->name);
202 0 : class_remove_groups(cls, cls->class_groups);
203 0 : kset_unregister(&cls->p->subsys);
204 0 : }
205 :
206 0 : static void class_create_release(struct class *cls)
207 : {
208 0 : pr_debug("%s called for %s\n", __func__, cls->name);
209 0 : kfree(cls);
210 0 : }
211 :
212 : /**
213 : * __class_create - create a struct class structure
214 : * @owner: pointer to the module that is to "own" this struct class
215 : * @name: pointer to a string for the name of this class.
216 : * @key: the lock_class_key for this class; used by mutex lock debugging
217 : *
218 : * This is used to create a struct class pointer that can then be used
219 : * in calls to device_create().
220 : *
221 : * Returns &struct class pointer on success, or ERR_PTR() on error.
222 : *
223 : * Note, the pointer created here is to be destroyed when finished by
224 : * making a call to class_destroy().
225 : */
226 8 : struct class *__class_create(struct module *owner, const char *name,
227 : struct lock_class_key *key)
228 : {
229 8 : struct class *cls;
230 8 : int retval;
231 :
232 8 : cls = kzalloc(sizeof(*cls), GFP_KERNEL);
233 8 : if (!cls) {
234 0 : retval = -ENOMEM;
235 0 : goto error;
236 : }
237 :
238 8 : cls->name = name;
239 8 : cls->owner = owner;
240 8 : cls->class_release = class_create_release;
241 :
242 8 : retval = __class_register(cls, key);
243 8 : if (retval)
244 0 : goto error;
245 :
246 : return cls;
247 :
248 0 : error:
249 0 : kfree(cls);
250 0 : return ERR_PTR(retval);
251 : }
252 : EXPORT_SYMBOL_GPL(__class_create);
253 :
254 : /**
255 : * class_destroy - destroys a struct class structure
256 : * @cls: pointer to the struct class that is to be destroyed
257 : *
258 : * Note, the pointer to be destroyed must have been created with a call
259 : * to class_create().
260 : */
261 0 : void class_destroy(struct class *cls)
262 : {
263 0 : if ((cls == NULL) || (IS_ERR(cls)))
264 : return;
265 :
266 0 : class_unregister(cls);
267 : }
268 :
269 : /**
270 : * class_dev_iter_init - initialize class device iterator
271 : * @iter: class iterator to initialize
272 : * @class: the class we wanna iterate over
273 : * @start: the device to start iterating from, if any
274 : * @type: device_type of the devices to iterate over, NULL for all
275 : *
276 : * Initialize class iterator @iter such that it iterates over devices
277 : * of @class. If @start is set, the list iteration will start there,
278 : * otherwise if it is NULL, the iteration starts at the beginning of
279 : * the list.
280 : */
281 169 : void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
282 : struct device *start, const struct device_type *type)
283 : {
284 169 : struct klist_node *start_knode = NULL;
285 :
286 4 : if (start)
287 0 : start_knode = &start->p->knode_class;
288 167 : klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
289 169 : iter->type = type;
290 165 : }
291 : EXPORT_SYMBOL_GPL(class_dev_iter_init);
292 :
293 : /**
294 : * class_dev_iter_next - iterate to the next device
295 : * @iter: class iterator to proceed
296 : *
297 : * Proceed @iter to the next device and return it. Returns NULL if
298 : * iteration is complete.
299 : *
300 : * The returned device is referenced and won't be released till
301 : * iterator is proceed to the next device or exited. The caller is
302 : * free to do whatever it wants to do with the device including
303 : * calling back into class code.
304 : */
305 9378 : struct device *class_dev_iter_next(struct class_dev_iter *iter)
306 : {
307 9381 : struct klist_node *knode;
308 9381 : struct device *dev;
309 :
310 9381 : while (1) {
311 9381 : knode = klist_next(&iter->ki);
312 9381 : if (!knode)
313 : return NULL;
314 9376 : dev = klist_class_to_dev(knode);
315 9376 : if (!iter->type || iter->type == dev->type)
316 9373 : return dev;
317 : }
318 : }
319 : EXPORT_SYMBOL_GPL(class_dev_iter_next);
320 :
321 : /**
322 : * class_dev_iter_exit - finish iteration
323 : * @iter: class iterator to finish
324 : *
325 : * Finish an iteration. Always call this function after iteration is
326 : * complete whether the iteration ran till the end or not.
327 : */
328 169 : void class_dev_iter_exit(struct class_dev_iter *iter)
329 : {
330 4 : klist_iter_exit(&iter->ki);
331 2 : }
332 : EXPORT_SYMBOL_GPL(class_dev_iter_exit);
333 :
334 : /**
335 : * class_for_each_device - device iterator
336 : * @class: the class we're iterating
337 : * @start: the device to start with in the list, if any.
338 : * @data: data for the callback
339 : * @fn: function to be called for each device
340 : *
341 : * Iterate over @class's list of devices, and call @fn for each,
342 : * passing it @data. If @start is set, the list iteration will start
343 : * there, otherwise if it is NULL, the iteration starts at the
344 : * beginning of the list.
345 : *
346 : * We check the return of @fn each time. If it returns anything
347 : * other than 0, we break out and return that value.
348 : *
349 : * @fn is allowed to do anything including calling back into class
350 : * code. There's no locking restriction.
351 : */
352 0 : int class_for_each_device(struct class *class, struct device *start,
353 : void *data, int (*fn)(struct device *, void *))
354 : {
355 0 : struct class_dev_iter iter;
356 0 : struct device *dev;
357 0 : int error = 0;
358 :
359 0 : if (!class)
360 : return -EINVAL;
361 0 : if (!class->p) {
362 0 : WARN(1, "%s called for class '%s' before it was initialized",
363 : __func__, class->name);
364 0 : return -EINVAL;
365 : }
366 :
367 0 : class_dev_iter_init(&iter, class, start, NULL);
368 0 : while ((dev = class_dev_iter_next(&iter))) {
369 0 : error = fn(dev, data);
370 0 : if (error)
371 : break;
372 : }
373 0 : class_dev_iter_exit(&iter);
374 :
375 0 : return error;
376 : }
377 : EXPORT_SYMBOL_GPL(class_for_each_device);
378 :
379 : /**
380 : * class_find_device - device iterator for locating a particular device
381 : * @class: the class we're iterating
382 : * @start: Device to begin with
383 : * @data: data for the match function
384 : * @match: function to check device
385 : *
386 : * This is similar to the class_for_each_dev() function above, but it
387 : * returns a reference to a device that is 'found' for later use, as
388 : * determined by the @match callback.
389 : *
390 : * The callback should return 0 if the device doesn't match and non-zero
391 : * if it does. If the callback returns non-zero, this function will
392 : * return to the caller and not iterate over any more devices.
393 : *
394 : * Note, you will need to drop the reference with put_device() after use.
395 : *
396 : * @match is allowed to do anything including calling back into class
397 : * code. There's no locking restriction.
398 : */
399 163 : struct device *class_find_device(struct class *class, struct device *start,
400 : const void *data,
401 : int (*match)(struct device *, const void *))
402 : {
403 163 : struct class_dev_iter iter;
404 163 : struct device *dev;
405 :
406 163 : if (!class)
407 : return NULL;
408 163 : if (!class->p) {
409 0 : WARN(1, "%s called for class '%s' before it was initialized",
410 : __func__, class->name);
411 0 : return NULL;
412 : }
413 :
414 163 : class_dev_iter_init(&iter, class, start, NULL);
415 9337 : while ((dev = class_dev_iter_next(&iter))) {
416 9337 : if (match(dev, data)) {
417 163 : get_device(dev);
418 163 : break;
419 : }
420 : }
421 163 : class_dev_iter_exit(&iter);
422 :
423 163 : return dev;
424 : }
425 : EXPORT_SYMBOL_GPL(class_find_device);
426 :
427 2 : int class_interface_register(struct class_interface *class_intf)
428 : {
429 2 : struct class *parent;
430 2 : struct class_dev_iter iter;
431 2 : struct device *dev;
432 :
433 2 : if (!class_intf || !class_intf->class)
434 : return -ENODEV;
435 :
436 2 : parent = class_get(class_intf->class);
437 2 : if (!parent)
438 : return -EINVAL;
439 :
440 2 : mutex_lock(&parent->p->mutex);
441 2 : list_add_tail(&class_intf->node, &parent->p->interfaces);
442 2 : if (class_intf->add_dev) {
443 2 : class_dev_iter_init(&iter, parent, NULL, NULL);
444 2 : while ((dev = class_dev_iter_next(&iter)))
445 0 : class_intf->add_dev(dev, class_intf);
446 2 : class_dev_iter_exit(&iter);
447 : }
448 2 : mutex_unlock(&parent->p->mutex);
449 :
450 2 : return 0;
451 : }
452 :
453 0 : void class_interface_unregister(struct class_interface *class_intf)
454 : {
455 0 : struct class *parent = class_intf->class;
456 0 : struct class_dev_iter iter;
457 0 : struct device *dev;
458 :
459 0 : if (!parent)
460 0 : return;
461 :
462 0 : mutex_lock(&parent->p->mutex);
463 0 : list_del_init(&class_intf->node);
464 0 : if (class_intf->remove_dev) {
465 0 : class_dev_iter_init(&iter, parent, NULL, NULL);
466 0 : while ((dev = class_dev_iter_next(&iter)))
467 0 : class_intf->remove_dev(dev, class_intf);
468 0 : class_dev_iter_exit(&iter);
469 : }
470 0 : mutex_unlock(&parent->p->mutex);
471 :
472 0 : class_put(parent);
473 : }
474 :
475 0 : ssize_t show_class_attr_string(struct class *class,
476 : struct class_attribute *attr, char *buf)
477 : {
478 0 : struct class_attribute_string *cs;
479 :
480 0 : cs = container_of(attr, struct class_attribute_string, attr);
481 0 : return sysfs_emit(buf, "%s\n", cs->str);
482 : }
483 :
484 : EXPORT_SYMBOL_GPL(show_class_attr_string);
485 :
486 : struct class_compat {
487 : struct kobject *kobj;
488 : };
489 :
490 : /**
491 : * class_compat_register - register a compatibility class
492 : * @name: the name of the class
493 : *
494 : * Compatibility class are meant as a temporary user-space compatibility
495 : * workaround when converting a family of class devices to a bus devices.
496 : */
497 0 : struct class_compat *class_compat_register(const char *name)
498 : {
499 0 : struct class_compat *cls;
500 :
501 0 : cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
502 0 : if (!cls)
503 : return NULL;
504 0 : cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
505 0 : if (!cls->kobj) {
506 0 : kfree(cls);
507 0 : return NULL;
508 : }
509 : return cls;
510 : }
511 : EXPORT_SYMBOL_GPL(class_compat_register);
512 :
513 : /**
514 : * class_compat_unregister - unregister a compatibility class
515 : * @cls: the class to unregister
516 : */
517 0 : void class_compat_unregister(struct class_compat *cls)
518 : {
519 0 : kobject_put(cls->kobj);
520 0 : kfree(cls);
521 0 : }
522 : EXPORT_SYMBOL_GPL(class_compat_unregister);
523 :
524 : /**
525 : * class_compat_create_link - create a compatibility class device link to
526 : * a bus device
527 : * @cls: the compatibility class
528 : * @dev: the target bus device
529 : * @device_link: an optional device to which a "device" link should be created
530 : */
531 0 : int class_compat_create_link(struct class_compat *cls, struct device *dev,
532 : struct device *device_link)
533 : {
534 0 : int error;
535 :
536 0 : error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
537 0 : if (error)
538 : return error;
539 :
540 : /*
541 : * Optionally add a "device" link (typically to the parent), as a
542 : * class device would have one and we want to provide as much
543 : * backwards compatibility as possible.
544 : */
545 0 : if (device_link) {
546 0 : error = sysfs_create_link(&dev->kobj, &device_link->kobj,
547 : "device");
548 0 : if (error)
549 0 : sysfs_remove_link(cls->kobj, dev_name(dev));
550 : }
551 :
552 : return error;
553 : }
554 : EXPORT_SYMBOL_GPL(class_compat_create_link);
555 :
556 : /**
557 : * class_compat_remove_link - remove a compatibility class device link to
558 : * a bus device
559 : * @cls: the compatibility class
560 : * @dev: the target bus device
561 : * @device_link: an optional device to which a "device" link was previously
562 : * created
563 : */
564 0 : void class_compat_remove_link(struct class_compat *cls, struct device *dev,
565 : struct device *device_link)
566 : {
567 0 : if (device_link)
568 0 : sysfs_remove_link(&dev->kobj, "device");
569 0 : sysfs_remove_link(cls->kobj, dev_name(dev));
570 0 : }
571 : EXPORT_SYMBOL_GPL(class_compat_remove_link);
572 :
573 1 : int __init classes_init(void)
574 : {
575 1 : class_kset = kset_create_and_add("class", NULL, NULL);
576 1 : if (!class_kset)
577 0 : return -ENOMEM;
578 : return 0;
579 : }
580 :
581 : EXPORT_SYMBOL_GPL(class_create_file_ns);
582 : EXPORT_SYMBOL_GPL(class_remove_file_ns);
583 : EXPORT_SYMBOL_GPL(class_unregister);
584 : EXPORT_SYMBOL_GPL(class_destroy);
585 :
586 : EXPORT_SYMBOL_GPL(class_interface_register);
587 : EXPORT_SYMBOL_GPL(class_interface_unregister);
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