projects/linux·blob v3.7 · 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 const void *class_attr_namespace(struct kobject *kobj,
51 const struct attribute *attr)
52{
53 struct class_attribute *class_attr = to_class_attr(attr);
54 struct subsys_private *cp = to_subsys_private(kobj);
55 const void *ns = NULL;
56
57 if (class_attr->namespace)
58 ns = class_attr->namespace(cp->class, class_attr);
59 return ns;
60}
61
62static void class_release(struct kobject *kobj)
63{
64 struct subsys_private *cp = to_subsys_private(kobj);
65 struct class *class = cp->class;
66
67 pr_debug("class '%s': release.\n", class->name);
68
69 if (class->class_release)
70 class->class_release(class);
71 else
72 pr_debug("class '%s' does not have a release() function, "
73 "be careful\n", class->name);
74
75 kfree(cp);
76}
77
78static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
79{
80 struct subsys_private *cp = to_subsys_private(kobj);
81 struct class *class = cp->class;
82
83 return class->ns_type;
84}
85
86static const struct sysfs_ops class_sysfs_ops = {
87 .show = class_attr_show,
88 .store = class_attr_store,
89 .namespace = class_attr_namespace,
90};
91
92static struct kobj_type class_ktype = {
93 .sysfs_ops = &class_sysfs_ops,
94 .release = class_release,
95 .child_ns_type = class_child_ns_type,
96};
97
98/* Hotplug events for classes go to the class subsys */
99static struct kset *class_kset;
100
101
102int class_create_file(struct class *cls, const struct class_attribute *attr)
103{
104 int error;
105 if (cls)
106 error = sysfs_create_file(&cls->p->subsys.kobj,
107 &attr->attr);
108 else
109 error = -EINVAL;
110 return error;
111}
112
113void class_remove_file(struct class *cls, const struct class_attribute *attr)
114{
115 if (cls)
116 sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);
117}
118
119static struct class *class_get(struct class *cls)
120{
121 if (cls)
122 kset_get(&cls->p->subsys);
123 return cls;
124}
125
126static void class_put(struct class *cls)
127{
128 if (cls)
129 kset_put(&cls->p->subsys);
130}
131
132static int add_class_attrs(struct class *cls)
133{
134 int i;
135 int error = 0;
136
137 if (cls->class_attrs) {
138 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
139 error = class_create_file(cls, &cls->class_attrs[i]);
140 if (error)
141 goto error;
142 }
143 }
144done:
145 return error;
146error:
147 while (--i >= 0)
148 class_remove_file(cls, &cls->class_attrs[i]);
149 goto done;
150}
151
152static void remove_class_attrs(struct class *cls)
153{
154 int i;
155
156 if (cls->class_attrs) {
157 for (i = 0; attr_name(cls->class_attrs[i]); i++)
158 class_remove_file(cls, &cls->class_attrs[i]);
159 }
160}
161
162static void klist_class_dev_get(struct klist_node *n)
163{
164 struct device *dev = container_of(n, struct device, knode_class);
165
166 get_device(dev);
167}
168
169static void klist_class_dev_put(struct klist_node *n)
170{
171 struct device *dev = container_of(n, struct device, knode_class);
172
173 put_device(dev);
174}
175
176int __class_register(struct class *cls, struct lock_class_key *key)
177{
178 struct subsys_private *cp;
179 int error;
180
181 pr_debug("device class '%s': registering\n", cls->name);
182
183 cp = kzalloc(sizeof(*cp), GFP_KERNEL);
184 if (!cp)
185 return -ENOMEM;
186 klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
187 INIT_LIST_HEAD(&cp->interfaces);
188 kset_init(&cp->glue_dirs);
189 __mutex_init(&cp->mutex, "subsys mutex", key);
190 error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
191 if (error) {
192 kfree(cp);
193 return error;
194 }
195
196 /* set the default /sys/dev directory for devices of this class */
197 if (!cls->dev_kobj)
198 cls->dev_kobj = sysfs_dev_char_kobj;
199
200#if defined(CONFIG_BLOCK)
201 /* let the block class directory show up in the root of sysfs */
202 if (!sysfs_deprecated || cls != &block_class)
203 cp->subsys.kobj.kset = class_kset;
204#else
205 cp->subsys.kobj.kset = class_kset;
206#endif
207 cp->subsys.kobj.ktype = &class_ktype;
208 cp->class = cls;
209 cls->p = cp;
210
211 error = kset_register(&cp->subsys);
212 if (error) {
213 kfree(cp);
214 return error;
215 }
216 error = add_class_attrs(class_get(cls));
217 class_put(cls);
218 return error;
219}
220EXPORT_SYMBOL_GPL(__class_register);
221
222void class_unregister(struct class *cls)
223{
224 pr_debug("device class '%s': unregistering\n", cls->name);
225 remove_class_attrs(cls);
226 kset_unregister(&cls->p->subsys);
227}
228
229static void class_create_release(struct class *cls)
230{
231 pr_debug("%s called for %s\n", __func__, cls->name);
232 kfree(cls);
233}
234
235/**
236 * class_create - create a struct class structure
237 * @owner: pointer to the module that is to "own" this struct class
238 * @name: pointer to a string for the name of this class.
239 * @key: the lock_class_key for this class; used by mutex lock debugging
240 *
241 * This is used to create a struct class pointer that can then be used
242 * in calls to device_create().
243 *
244 * Returns &struct class pointer on success, or ERR_PTR() on error.
245 *
246 * Note, the pointer created here is to be destroyed when finished by
247 * making a call to class_destroy().
248 */
249struct class *__class_create(struct module *owner, const char *name,
250 struct lock_class_key *key)
251{
252 struct class *cls;
253 int retval;
254
255 cls = kzalloc(sizeof(*cls), GFP_KERNEL);
256 if (!cls) {
257 retval = -ENOMEM;
258 goto error;
259 }
260
261 cls->name = name;
262 cls->owner = owner;
263 cls->class_release = class_create_release;
264
265 retval = __class_register(cls, key);
266 if (retval)
267 goto error;
268
269 return cls;
270
271error:
272 kfree(cls);
273 return ERR_PTR(retval);
274}
275EXPORT_SYMBOL_GPL(__class_create);
276
277/**
278 * class_destroy - destroys a struct class structure
279 * @cls: pointer to the struct class that is to be destroyed
280 *
281 * Note, the pointer to be destroyed must have been created with a call
282 * to class_create().
283 */
284void class_destroy(struct class *cls)
285{
286 if ((cls == NULL) || (IS_ERR(cls)))
287 return;
288
289 class_unregister(cls);
290}
291
292/**
293 * class_dev_iter_init - initialize class device iterator
294 * @iter: class iterator to initialize
295 * @class: the class we wanna iterate over
296 * @start: the device to start iterating from, if any
297 * @type: device_type of the devices to iterate over, NULL for all
298 *
299 * Initialize class iterator @iter such that it iterates over devices
300 * of @class. If @start is set, the list iteration will start there,
301 * otherwise if it is NULL, the iteration starts at the beginning of
302 * the list.
303 */
304void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
305 struct device *start, const struct device_type *type)
306{
307 struct klist_node *start_knode = NULL;
308
309 if (start)
310 start_knode = &start->knode_class;
311 klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
312 iter->type = type;
313}
314EXPORT_SYMBOL_GPL(class_dev_iter_init);
315
316/**
317 * class_dev_iter_next - iterate to the next device
318 * @iter: class iterator to proceed
319 *
320 * Proceed @iter to the next device and return it. Returns NULL if
321 * iteration is complete.
322 *
323 * The returned device is referenced and won't be released till
324 * iterator is proceed to the next device or exited. The caller is
325 * free to do whatever it wants to do with the device including
326 * calling back into class code.
327 */
328struct device *class_dev_iter_next(struct class_dev_iter *iter)
329{
330 struct klist_node *knode;
331 struct device *dev;
332
333 while (1) {
334 knode = klist_next(&iter->ki);
335 if (!knode)
336 return NULL;
337 dev = container_of(knode, struct device, knode_class);
338 if (!iter->type || iter->type == dev->type)
339 return dev;
340 }
341}
342EXPORT_SYMBOL_GPL(class_dev_iter_next);
343
344/**
345 * class_dev_iter_exit - finish iteration
346 * @iter: class iterator to finish
347 *
348 * Finish an iteration. Always call this function after iteration is
349 * complete whether the iteration ran till the end or not.
350 */
351void class_dev_iter_exit(struct class_dev_iter *iter)
352{
353 klist_iter_exit(&iter->ki);
354}
355EXPORT_SYMBOL_GPL(class_dev_iter_exit);
356
357/**
358 * class_for_each_device - device iterator
359 * @class: the class we're iterating
360 * @start: the device to start with in the list, if any.
361 * @data: data for the callback
362 * @fn: function to be called for each device
363 *
364 * Iterate over @class's list of devices, and call @fn for each,
365 * passing it @data. If @start is set, the list iteration will start
366 * there, otherwise if it is NULL, the iteration starts at the
367 * beginning of the list.
368 *
369 * We check the return of @fn each time. If it returns anything
370 * other than 0, we break out and return that value.
371 *
372 * @fn is allowed to do anything including calling back into class
373 * code. There's no locking restriction.
374 */
375int class_for_each_device(struct class *class, struct device *start,
376 void *data, int (*fn)(struct device *, void *))
377{
378 struct class_dev_iter iter;
379 struct device *dev;
380 int error = 0;
381
382 if (!class)
383 return -EINVAL;
384 if (!class->p) {
385 WARN(1, "%s called for class '%s' before it was initialized",
386 __func__, class->name);
387 return -EINVAL;
388 }
389
390 class_dev_iter_init(&iter, class, start, NULL);
391 while ((dev = class_dev_iter_next(&iter))) {
392 error = fn(dev, data);
393 if (error)
394 break;
395 }
396 class_dev_iter_exit(&iter);
397
398 return error;
399}
400EXPORT_SYMBOL_GPL(class_for_each_device);
401
402/**
403 * class_find_device - device iterator for locating a particular device
404 * @class: the class we're iterating
405 * @start: Device to begin with
406 * @data: data for the match function
407 * @match: function to check device
408 *
409 * This is similar to the class_for_each_dev() function above, but it
410 * returns a reference to a device that is 'found' for later use, as
411 * determined by the @match callback.
412 *
413 * The callback should return 0 if the device doesn't match and non-zero
414 * if it does. If the callback returns non-zero, this function will
415 * return to the caller and not iterate over any more devices.
416 *
417 * Note, you will need to drop the reference with put_device() after use.
418 *
419 * @fn is allowed to do anything including calling back into class
420 * code. There's no locking restriction.
421 */
422struct device *class_find_device(struct class *class, struct device *start,
423 void *data,
424 int (*match)(struct device *, void *))
425{
426 struct class_dev_iter iter;
427 struct device *dev;
428
429 if (!class)
430 return NULL;
431 if (!class->p) {
432 WARN(1, "%s called for class '%s' before it was initialized",
433 __func__, class->name);
434 return NULL;
435 }
436
437 class_dev_iter_init(&iter, class, start, NULL);
438 while ((dev = class_dev_iter_next(&iter))) {
439 if (match(dev, data)) {
440 get_device(dev);
441 break;
442 }
443 }
444 class_dev_iter_exit(&iter);
445
446 return dev;
447}
448EXPORT_SYMBOL_GPL(class_find_device);
449
450int class_interface_register(struct class_interface *class_intf)
451{
452 struct class *parent;
453 struct class_dev_iter iter;
454 struct device *dev;
455
456 if (!class_intf || !class_intf->class)
457 return -ENODEV;
458
459 parent = class_get(class_intf->class);
460 if (!parent)
461 return -EINVAL;
462
463 mutex_lock(&parent->p->mutex);
464 list_add_tail(&class_intf->node, &parent->p->interfaces);
465 if (class_intf->add_dev) {
466 class_dev_iter_init(&iter, parent, NULL, NULL);
467 while ((dev = class_dev_iter_next(&iter)))
468 class_intf->add_dev(dev, class_intf);
469 class_dev_iter_exit(&iter);
470 }
471 mutex_unlock(&parent->p->mutex);
472
473 return 0;
474}
475
476void class_interface_unregister(struct class_interface *class_intf)
477{
478 struct class *parent = class_intf->class;
479 struct class_dev_iter iter;
480 struct device *dev;
481
482 if (!parent)
483 return;
484
485 mutex_lock(&parent->p->mutex);
486 list_del_init(&class_intf->node);
487 if (class_intf->remove_dev) {
488 class_dev_iter_init(&iter, parent, NULL, NULL);
489 while ((dev = class_dev_iter_next(&iter)))
490 class_intf->remove_dev(dev, class_intf);
491 class_dev_iter_exit(&iter);
492 }
493 mutex_unlock(&parent->p->mutex);
494
495 class_put(parent);
496}
497
498ssize_t show_class_attr_string(struct class *class,
499 struct class_attribute *attr, char *buf)
500{
501 struct class_attribute_string *cs;
502 cs = container_of(attr, struct class_attribute_string, attr);
503 return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
504}
505
506EXPORT_SYMBOL_GPL(show_class_attr_string);
507
508struct class_compat {
509 struct kobject *kobj;
510};
511
512/**
513 * class_compat_register - register a compatibility class
514 * @name: the name of the class
515 *
516 * Compatibility class are meant as a temporary user-space compatibility
517 * workaround when converting a family of class devices to a bus devices.
518 */
519struct class_compat *class_compat_register(const char *name)
520{
521 struct class_compat *cls;
522
523 cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
524 if (!cls)
525 return NULL;
526 cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
527 if (!cls->kobj) {
528 kfree(cls);
529 return NULL;
530 }
531 return cls;
532}
533EXPORT_SYMBOL_GPL(class_compat_register);
534
535/**
536 * class_compat_unregister - unregister a compatibility class
537 * @cls: the class to unregister
538 */
539void class_compat_unregister(struct class_compat *cls)
540{
541 kobject_put(cls->kobj);
542 kfree(cls);
543}
544EXPORT_SYMBOL_GPL(class_compat_unregister);
545
546/**
547 * class_compat_create_link - create a compatibility class device link to
548 * a bus device
549 * @cls: the compatibility class
550 * @dev: the target bus device
551 * @device_link: an optional device to which a "device" link should be created
552 */
553int class_compat_create_link(struct class_compat *cls, struct device *dev,
554 struct device *device_link)
555{
556 int error;
557
558 error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
559 if (error)
560 return error;
561
562 /*
563 * Optionally add a "device" link (typically to the parent), as a
564 * class device would have one and we want to provide as much
565 * backwards compatibility as possible.
566 */
567 if (device_link) {
568 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
569 "device");
570 if (error)
571 sysfs_remove_link(cls->kobj, dev_name(dev));
572 }
573
574 return error;
575}
576EXPORT_SYMBOL_GPL(class_compat_create_link);
577
578/**
579 * class_compat_remove_link - remove a compatibility class device link to
580 * a bus device
581 * @cls: the compatibility class
582 * @dev: the target bus device
583 * @device_link: an optional device to which a "device" link was previously
584 * created
585 */
586void class_compat_remove_link(struct class_compat *cls, struct device *dev,
587 struct device *device_link)
588{
589 if (device_link)
590 sysfs_remove_link(&dev->kobj, "device");
591 sysfs_remove_link(cls->kobj, dev_name(dev));
592}
593EXPORT_SYMBOL_GPL(class_compat_remove_link);
594
595int __init classes_init(void)
596{
597 class_kset = kset_create_and_add("class", NULL, NULL);
598 if (!class_kset)
599 return -ENOMEM;
600 return 0;
601}
602
603EXPORT_SYMBOL_GPL(class_create_file);
604EXPORT_SYMBOL_GPL(class_remove_file);
605EXPORT_SYMBOL_GPL(class_unregister);
606EXPORT_SYMBOL_GPL(class_destroy);
607
608EXPORT_SYMBOL_GPL(class_interface_register);
609EXPORT_SYMBOL_GPL(class_interface_unregister);