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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
26 static 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
38 static 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
50 static 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
66 static 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
74 static const struct sysfs_ops class_sysfs_ops = {
75 .show = class_attr_show,
76 .store = class_attr_store,
77 };
78
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,
83 };
84
85 /* Hotplug events for classes go to the class subsys */
86 static struct kset *class_kset;
87
88
89 int 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
102 void 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
109 static struct class *class_get(struct class *cls)
110 {
111 if (cls)
112 kset_get(&cls->p->subsys);
113 return cls;
114 }
115
116 static void class_put(struct class *cls)
117 {
118 if (cls)
119 kset_put(&cls->p->subsys);
120 }
121
122 static 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 }
134 done:
135 return error;
136 error:
137 while (--i >= 0)
138 class_remove_file(cls, &cls->class_attrs[i]);
139 goto done;
140 }
141
142 static 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
152 static 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
159 static 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
166 static int class_add_groups(struct class *cls,
167 const struct attribute_group **groups)
168 {
169 return sysfs_create_groups(&cls->p->subsys.kobj, groups);
170 }
171
172 static void class_remove_groups(struct class *cls,
173 const struct attribute_group **groups)
174 {
175 return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
176 }
177
178 int __class_register(struct class *cls, struct lock_class_key *key)
179 {
180 struct subsys_private *cp;
181 int error;
182
183 pr_debug("device class '%s': registering\n", cls->name);
184
185 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
186 if (!cp)
187 return -ENOMEM;
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);
193 if (error) {
194 kfree(cp);
195 return error;
196 }
197
198 /* set the default /sys/dev directory for devices of this class */
199 if (!cls->dev_kobj)
200 cls->dev_kobj = sysfs_dev_char_kobj;
201
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;
206 #else
207 cp->subsys.kobj.kset = class_kset;
208 #endif
209 cp->subsys.kobj.ktype = &class_ktype;
210 cp->class = cls;
211 cls->p = cp;
212
213 error = kset_register(&cp->subsys);
214 if (error) {
215 kfree(cp);
216 return error;
217 }
218 error = class_add_groups(class_get(cls), cls->class_groups);
219 class_put(cls);
220 error = add_class_attrs(class_get(cls));
221 class_put(cls);
222 return error;
223 }
224 EXPORT_SYMBOL_GPL(__class_register);
225
226 void class_unregister(struct class *cls)
227 {
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);
232 }
233
234 static void class_create_release(struct class *cls)
235 {
236 pr_debug("%s called for %s\n", __func__, cls->name);
237 kfree(cls);
238 }
239
240 /**
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
245 *
246 * This is used to create a struct class pointer that can then be used
247 * in calls to device_create().
248 *
249 * Returns &struct class pointer on success, or ERR_PTR() on error.
250 *
251 * Note, the pointer created here is to be destroyed when finished by
252 * making a call to class_destroy().
253 */
254 struct class *__class_create(struct module *owner, const char *name,
255 struct lock_class_key *key)
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->owner = owner;
268 cls->class_release = class_create_release;
269
270 retval = __class_register(cls, key);
271 if (retval)
272 goto error;
273
274 return cls;
275
276 error:
277 kfree(cls);
278 return ERR_PTR(retval);
279 }
280 EXPORT_SYMBOL_GPL(__class_create);
281
282 /**
283 * class_destroy - destroys a struct class structure
284 * @cls: pointer to the struct class that is to be destroyed
285 *
286 * Note, the pointer to be destroyed must have been created with a call
287 * to class_create().
288 */
289 void class_destroy(struct class *cls)
290 {
291 if ((cls == NULL) || (IS_ERR(cls)))
292 return;
293
294 class_unregister(cls);
295 }
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 */
309 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
310 struct device *start, const struct device_type *type)
311 {
312 struct klist_node *start_knode = NULL;
313
314 if (start)
315 start_knode = &start->knode_class;
316 klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
317 iter->type = type;
318 }
319 EXPORT_SYMBOL_GPL(class_dev_iter_init);
320
321 /**
322 * class_dev_iter_next - iterate to the next device
323 * @iter: class iterator to proceed
324 *
325 * Proceed @iter to the next device and return it. Returns NULL if
326 * iteration is complete.
327 *
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.
332 */
333 struct device *class_dev_iter_next(struct class_dev_iter *iter)
334 {
335 struct klist_node *knode;
336 struct device *dev;
337
338 while (1) {
339 knode = klist_next(&iter->ki);
340 if (!knode)
341 return NULL;
342 dev = container_of(knode, struct device, knode_class);
343 if (!iter->type || iter->type == dev->type)
344 return dev;
345 }
346 }
347 EXPORT_SYMBOL_GPL(class_dev_iter_next);
348
349 /**
350 * class_dev_iter_exit - finish iteration
351 * @iter: class iterator to finish
352 *
353 * Finish an iteration. Always call this function after iteration is
354 * complete whether the iteration ran till the end or not.
355 */
356 void class_dev_iter_exit(struct class_dev_iter *iter)
357 {
358 klist_iter_exit(&iter->ki);
359 }
360 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
361
362 /**
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
368 *
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.
373 *
374 * We check the return of @fn each time. If it returns anything
375 * other than 0, we break out and return that value.
376 *
377 * @fn is allowed to do anything including calling back into class
378 * code. There's no locking restriction.
379 */
380 int class_for_each_device(struct class *class, struct device *start,
381 void *data, int (*fn)(struct device *, void *))
382 {
383 struct class_dev_iter iter;
384 struct device *dev;
385 int error = 0;
386
387 if (!class)
388 return -EINVAL;
389 if (!class->p) {
390 WARN(1, "%s called for class '%s' before it was initialized",
391 __func__, class->name);
392 return -EINVAL;
393 }
394
395 class_dev_iter_init(&iter, class, start, NULL);
396 while ((dev = class_dev_iter_next(&iter))) {
397 error = fn(dev, data);
398 if (error)
399 break;
400 }
401 class_dev_iter_exit(&iter);
402
403 return error;
404 }
405 EXPORT_SYMBOL_GPL(class_for_each_device);
406
407 /**
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
413 *
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.
417 *
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.
421 *
422 * Note, you will need to drop the reference with put_device() after use.
423 *
424 * @match is allowed to do anything including calling back into class
425 * code. There's no locking restriction.
426 */
427 struct device *class_find_device(struct class *class, struct device *start,
428 const void *data,
429 int (*match)(struct device *, const void *))
430 {
431 struct class_dev_iter iter;
432 struct device *dev;
433
434 if (!class)
435 return NULL;
436 if (!class->p) {
437 WARN(1, "%s called for class '%s' before it was initialized",
438 __func__, class->name);
439 return NULL;
440 }
441
442 class_dev_iter_init(&iter, class, start, NULL);
443 while ((dev = class_dev_iter_next(&iter))) {
444 if (match(dev, data)) {
445 get_device(dev);
446 break;
447 }
448 }
449 class_dev_iter_exit(&iter);
450
451 return dev;
452 }
453 EXPORT_SYMBOL_GPL(class_find_device);
454
455 int class_interface_register(struct class_interface *class_intf)
456 {
457 struct class *parent;
458 struct class_dev_iter iter;
459 struct device *dev;
460
461 if (!class_intf || !class_intf->class)
462 return -ENODEV;
463
464 parent = class_get(class_intf->class);
465 if (!parent)
466 return -EINVAL;
467
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);
475 }
476 mutex_unlock(&parent->p->mutex);
477
478 return 0;
479 }
480
481 void class_interface_unregister(struct class_interface *class_intf)
482 {
483 struct class *parent = class_intf->class;
484 struct class_dev_iter iter;
485 struct device *dev;
486
487 if (!parent)
488 return;
489
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);
497 }
498 mutex_unlock(&parent->p->mutex);
499
500 class_put(parent);
501 }
502
503 ssize_t show_class_attr_string(struct class *class,
504 struct class_attribute *attr, char *buf)
505 {
506 struct class_attribute_string *cs;
507
508 cs = container_of(attr, struct class_attribute_string, attr);
509 return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
510 }
511
512 EXPORT_SYMBOL_GPL(show_class_attr_string);
513
514 struct class_compat {
515 struct kobject *kobj;
516 };
517
518 /**
519 * class_compat_register - register a compatibility class
520 * @name: the name of the class
521 *
522 * Compatibility class are meant as a temporary user-space compatibility
523 * workaround when converting a family of class devices to a bus devices.
524 */
525 struct class_compat *class_compat_register(const char *name)
526 {
527 struct class_compat *cls;
528
529 cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
530 if (!cls)
531 return NULL;
532 cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
533 if (!cls->kobj) {
534 kfree(cls);
535 return NULL;
536 }
537 return cls;
538 }
539 EXPORT_SYMBOL_GPL(class_compat_register);
540
541 /**
542 * class_compat_unregister - unregister a compatibility class
543 * @cls: the class to unregister
544 */
545 void class_compat_unregister(struct class_compat *cls)
546 {
547 kobject_put(cls->kobj);
548 kfree(cls);
549 }
550 EXPORT_SYMBOL_GPL(class_compat_unregister);
551
552 /**
553 * class_compat_create_link - create a compatibility class device link to
554 * a bus device
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
558 */
559 int class_compat_create_link(struct class_compat *cls, struct device *dev,
560 struct device *device_link)
561 {
562 int error;
563
564 error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
565 if (error)
566 return error;
567
568 /*
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.
572 */
573 if (device_link) {
574 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
575 "device");
576 if (error)
577 sysfs_remove_link(cls->kobj, dev_name(dev));
578 }
579
580 return error;
581 }
582 EXPORT_SYMBOL_GPL(class_compat_create_link);
583
584 /**
585 * class_compat_remove_link - remove a compatibility class device link to
586 * a bus device
587 * @cls: the compatibility class
588 * @dev: the target bus device
589 * @device_link: an optional device to which a "device" link was previously
590 * created
591 */
592 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
593 struct device *device_link)
594 {
595 if (device_link)
596 sysfs_remove_link(&dev->kobj, "device");
597 sysfs_remove_link(cls->kobj, dev_name(dev));
598 }
599 EXPORT_SYMBOL_GPL(class_compat_remove_link);
600
601 int __init classes_init(void)
602 {
603 class_kset = kset_create_and_add("class", NULL, NULL);
604 if (!class_kset)
605 return -ENOMEM;
606 return 0;
607 }
608
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);
613
614 EXPORT_SYMBOL_GPL(class_interface_register);
615 EXPORT_SYMBOL_GPL(class_interface_unregister);