projects/linux·blob v4.13 · refs

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