aboutsummaryrefslogtreecommitdiff
path: root/drivers/base/class.c
blob: d8a6a5864c2ee0326da668a715d132adb7342093 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
// SPDX-License-Identifier: GPL-2.0
/*
 * class.c - basic device class management
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 * Copyright (c) 2003-2004 Greg Kroah-Hartman
 * Copyright (c) 2003-2004 IBM Corp.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/mutex.h>
#include "base.h"

#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)

static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
			       char *buf)
{
	struct class_attribute *class_attr = to_class_attr(attr);
	struct subsys_private *cp = to_subsys_private(kobj);
	ssize_t ret = -EIO;

	if (class_attr->show)
		ret = class_attr->show(cp->class, class_attr, buf);
	return ret;
}

static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
				const char *buf, size_t count)
{
	struct class_attribute *class_attr = to_class_attr(attr);
	struct subsys_private *cp = to_subsys_private(kobj);
	ssize_t ret = -EIO;

	if (class_attr->store)
		ret = class_attr->store(cp->class, class_attr, buf, count);
	return ret;
}

static void class_release(struct kobject *kobj)
{
	struct subsys_private *cp = to_subsys_private(kobj);
	struct class *class = cp->class;

	pr_debug("class '%s': release.\n", class->name);

	if (class->class_release)
		class->class_release(class);
	else
		pr_debug("class '%s' does not have a release() function, "
			 "be careful\n", class->name);

	kfree(cp);
}

static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
{
	struct subsys_private *cp = to_subsys_private(kobj);
	struct class *class = cp->class;

	return class->ns_type;
}

static const struct sysfs_ops class_sysfs_ops = {
	.show	   = class_attr_show,
	.store	   = class_attr_store,
};

static struct kobj_type class_ktype = {
	.sysfs_ops	= &class_sysfs_ops,
	.release	= class_release,
	.child_ns_type	= class_child_ns_type,
};

/* Hotplug events for classes go to the class subsys */
static struct kset *class_kset;


int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
			 const void *ns)
{
	int error;

	if (cls)
		error = sysfs_create_file_ns(&cls->p->subsys.kobj,
					     &attr->attr, ns);
	else
		error = -EINVAL;
	return error;
}

void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
			  const void *ns)
{
	if (cls)
		sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
}

static struct class *class_get(struct class *cls)
{
	if (cls)
		kset_get(&cls->p->subsys);
	return cls;
}

static void class_put(struct class *cls)
{
	if (cls)
		kset_put(&cls->p->subsys);
}

static struct device *klist_class_to_dev(struct klist_node *n)
{
	struct device_private *p = to_device_private_class(n);
	return p->device;
}

static void klist_class_dev_get(struct klist_node *n)
{
	struct device *dev = klist_class_to_dev(n);

	get_device(dev);
}

static void klist_class_dev_put(struct klist_node *n)
{
	struct device *dev = klist_class_to_dev(n);

	put_device(dev);
}

static int class_add_groups(struct class *cls,
			    const struct attribute_group **groups)
{
	return sysfs_create_groups(&cls->p->subsys.kobj, groups);
}

static void class_remove_groups(struct class *cls,
				const struct attribute_group **groups)
{
	return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
}

int __class_register(struct class *cls, struct lock_class_key *key)
{
	struct subsys_private *cp;
	int error;

	pr_debug("device class '%s': registering\n", cls->name);

	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
	if (!cp)
		return -ENOMEM;
	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
	INIT_LIST_HEAD(&cp->interfaces);
	kset_init(&cp->glue_dirs);
	__mutex_init(&cp->mutex, "subsys mutex", key);
	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
	if (error) {
		kfree(cp);
		return error;
	}

	/* set the default /sys/dev directory for devices of this class */
	if (!cls->dev_kobj)
		cls->dev_kobj = sysfs_dev_char_kobj;

#if defined(CONFIG_BLOCK)
	/* let the block class directory show up in the root of sysfs */
	if (!sysfs_deprecated || cls != &block_class)
		cp->subsys.kobj.kset = class_kset;
#else
	cp->subsys.kobj.kset = class_kset;
#endif
	cp->subsys.kobj.ktype = &class_ktype;
	cp->class = cls;
	cls->p = cp;

	error = kset_register(&cp->subsys);
	if (error) {
		kfree(cp);
		return error;
	}
	error = class_add_groups(class_get(cls), cls->class_groups);
	class_put(cls);
	return error;
}
EXPORT_SYMBOL_GPL(__class_register);

void class_unregister(struct class *cls)
{
	pr_debug("device class '%s': unregistering\n", cls->name);
	class_remove_groups(cls, cls->class_groups);
	kset_unregister(&cls->p->subsys);
}

static void class_create_release(struct class *cls)
{
	pr_debug("%s called for %s\n", __func__, cls->name);
	kfree(cls);
}

/**
 * class_create - create a struct class structure
 * @owner: pointer to the module that is to "own" this struct class
 * @name: pointer to a string for the name of this class.
 * @key: the lock_class_key for this class; used by mutex lock debugging
 *
 * This is used to create a struct class pointer that can then be used
 * in calls to device_create().
 *
 * Returns &struct class pointer on success, or ERR_PTR() on error.
 *
 * Note, the pointer created here is to be destroyed when finished by
 * making a call to class_destroy().
 */
struct class *__class_create(struct module *owner, const char *name,
			     struct lock_class_key *key)
{
	struct class *cls;
	int retval;

	cls = kzalloc(sizeof(*cls), GFP_KERNEL);
	if (!cls) {
		retval = -ENOMEM;
		goto error;
	}

	cls->name = name;
	cls->owner = owner;
	cls->class_release = class_create_release;

	retval = __class_register(cls, key);
	if (retval)
		goto error;

	return cls;

error:
	kfree(cls);
	return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(__class_create);

/**
 * class_destroy - destroys a struct class structure
 * @cls: pointer to the struct class that is to be destroyed
 *
 * Note, the pointer to be destroyed must have been created with a call
 * to class_create().
 */
void class_destroy(struct class *cls)
{
	if ((cls == NULL) || (IS_ERR(cls)))
		return;

	class_unregister(cls);
}

/**
 * class_dev_iter_init - initialize class device iterator
 * @iter: class iterator to initialize
 * @class: the class we wanna iterate over
 * @start: the device to start iterating from, if any
 * @type: device_type of the devices to iterate over, NULL for all
 *
 * Initialize class iterator @iter such that it iterates over devices
 * of @class.  If @start is set, the list iteration will start there,
 * otherwise if it is NULL, the iteration starts at the beginning of
 * the list.
 */
void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
			 struct device *start, const struct device_type *type)
{
	struct klist_node *start_knode = NULL;

	if (start)
		start_knode = &start->p->knode_class;
	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
	iter->type = type;
}
EXPORT_SYMBOL_GPL(class_dev_iter_init);

/**
 * class_dev_iter_next - iterate to the next device
 * @iter: class iterator to proceed
 *
 * Proceed @iter to the next device and return it.  Returns NULL if
 * iteration is complete.
 *
 * The returned device is referenced and won't be released till
 * iterator is proceed to the next device or exited.  The caller is
 * free to do whatever it wants to do with the device including
 * calling back into class code.
 */
struct device *class_dev_iter_next(struct class_dev_iter *iter)
{
	struct klist_node *knode;
	struct device *dev;

	while (1) {
		knode = klist_next(&iter->ki);
		if (!knode)
			return NULL;
		dev = klist_class_to_dev(knode);
		if (!iter->type || iter->type == dev->type)
			return dev;
	}
}
EXPORT_SYMBOL_GPL(class_dev_iter_next);

/**
 * class_dev_iter_exit - finish iteration
 * @iter: class iterator to finish
 *
 * Finish an iteration.  Always call this function after iteration is
 * complete whether the iteration ran till the end or not.
 */
void class_dev_iter_exit(struct class_dev_iter *iter)
{
	klist_iter_exit(&iter->ki);
}
EXPORT_SYMBOL_GPL(class_dev_iter_exit);

/**
 * class_for_each_device - device iterator
 * @class: the class we're iterating
 * @start: the device to start with in the list, if any.
 * @data: data for the callback
 * @fn: function to be called for each device
 *
 * Iterate over @class's list of devices, and call @fn for each,
 * passing it @data.  If @start is set, the list iteration will start
 * there, otherwise if it is NULL, the iteration starts at the
 * beginning of the list.
 *
 * We check the return of @fn each time. If it returns anything
 * other than 0, we break out and return that value.
 *
 * @fn is allowed to do anything including calling back into class
 * code.  There's no locking restriction.
 */
int class_for_each_device(struct class *class, struct device *start,
			  void *data, int (*fn)(struct device *, void *))
{
	struct class_dev_iter iter;
	struct device *dev;
	int error = 0;

	if (!class)
		return -EINVAL;
	if (!class->p) {
		WARN(1, "%s called for class '%s' before it was initialized",
		     __func__, class->name);
		return -EINVAL;
	}

	class_dev_iter_init(&iter, class, start, NULL);
	while ((dev = class_dev_iter_next(&iter))) {
		error = fn(dev, data);
		if (error)
			break;
	}
	class_dev_iter_exit(&iter);

	return error;
}
EXPORT_SYMBOL_GPL(class_for_each_device);

/**
 * class_find_device - device iterator for locating a particular device
 * @class: the class we're iterating
 * @start: Device to begin with
 * @data: data for the match function
 * @match: function to check device
 *
 * This is similar to the class_for_each_dev() function above, but it
 * returns a reference to a device that is 'found' for later use, as
 * determined by the @match callback.
 *
 * The callback should return 0 if the device doesn't match and non-zero
 * if it does.  If the callback returns non-zero, this function will
 * return to the caller and not iterate over any more devices.
 *
 * Note, you will need to drop the reference with put_device() after use.
 *
 * @match is allowed to do anything including calling back into class
 * code.  There's no locking restriction.
 */
struct device *class_find_device(struct class *class, struct device *start,
				 const void *data,
				 int (*match)(struct device *, const void *))
{
	struct class_dev_iter iter;
	struct device *dev;

	if (!class)
		return NULL;
	if (!class->p) {
		WARN(1, "%s called for class '%s' before it was initialized",
		     __func__, class->name);
		return NULL;
	}

	class_dev_iter_init(&iter, class, start, NULL);
	while ((dev = class_dev_iter_next(&iter))) {
		if (match(dev, data)) {
			get_device(dev);
			break;
		}
	}
	class_dev_iter_exit(&iter);

	return dev;
}
EXPORT_SYMBOL_GPL(class_find_device);

int class_interface_register(struct class_interface *class_intf)
{
	struct class *parent;
	struct class_dev_iter iter;
	struct device *dev;

	if (!class_intf || !class_intf->class)
		return -ENODEV;

	parent = class_get(class_intf->class);
	if (!parent)
		return -EINVAL;

	mutex_lock(&parent->p->mutex);
	list_add_tail(&class_intf->node, &parent->p->interfaces);
	if (class_intf->add_dev) {
		class_dev_iter_init(&iter, parent, NULL, NULL);
		while ((dev = class_dev_iter_next(&iter)))
			class_intf->add_dev(dev, class_intf);
		class_dev_iter_exit(&iter);
	}
	mutex_unlock(&parent->p->mutex);

	return 0;
}

void class_interface_unregister(struct class_interface *class_intf)
{
	struct class *parent = class_intf->class;
	struct class_dev_iter iter;
	struct device *dev;

	if (!parent)
		return;

	mutex_lock(&parent->p->mutex);
	list_del_init(&class_intf->node);
	if (class_intf->remove_dev) {
		class_dev_iter_init(&iter, parent, NULL, NULL);
		while ((dev = class_dev_iter_next(&iter)))
			class_intf->remove_dev(dev, class_intf);
		class_dev_iter_exit(&iter);
	}
	mutex_unlock(&parent->p->mutex);

	class_put(parent);
}

ssize_t show_class_attr_string(struct class *class,
			       struct class_attribute *attr, char *buf)
{
	struct class_attribute_string *cs;

	cs = container_of(attr, struct class_attribute_string, attr);
	return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
}

EXPORT_SYMBOL_GPL(show_class_attr_string);

struct class_compat {
	struct kobject *kobj;
};

/**
 * class_compat_register - register a compatibility class
 * @name: the name of the class
 *
 * Compatibility class are meant as a temporary user-space compatibility
 * workaround when converting a family of class devices to a bus devices.
 */
struct class_compat *class_compat_register(const char *name)
{
	struct class_compat *cls;

	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
	if (!cls)
		return NULL;
	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
	if (!cls->kobj) {
		kfree(cls);
		return NULL;
	}
	return cls;
}
EXPORT_SYMBOL_GPL(class_compat_register);

/**
 * class_compat_unregister - unregister a compatibility class
 * @cls: the class to unregister
 */
void class_compat_unregister(struct class_compat *cls)
{
	kobject_put(cls->kobj);
	kfree(cls);
}
EXPORT_SYMBOL_GPL(class_compat_unregister);

/**
 * class_compat_create_link - create a compatibility class device link to
 *			      a bus device
 * @cls: the compatibility class
 * @dev: the target bus device
 * @device_link: an optional device to which a "device" link should be created
 */
int class_compat_create_link(struct class_compat *cls, struct device *dev,
			     struct device *device_link)
{
	int error;

	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
	if (error)
		return error;

	/*
	 * Optionally add a "device" link (typically to the parent), as a
	 * class device would have one and we want to provide as much
	 * backwards compatibility as possible.
	 */
	if (device_link) {
		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
					  "device");
		if (error)
			sysfs_remove_link(cls->kobj, dev_name(dev));
	}

	return error;
}
EXPORT_SYMBOL_GPL(class_compat_create_link);

/**
 * class_compat_remove_link - remove a compatibility class device link to
 *			      a bus device
 * @cls: the compatibility class
 * @dev: the target bus device
 * @device_link: an optional device to which a "device" link was previously
 * 		 created
 */
void class_compat_remove_link(struct class_compat *cls, struct device *dev,
			      struct device *device_link)
{
	if (device_link)
		sysfs_remove_link(&dev->kobj, "device");
	sysfs_remove_link(cls->kobj, dev_name(dev));
}
EXPORT_SYMBOL_GPL(class_compat_remove_link);

int __init classes_init(void)
{
	class_kset = kset_create_and_add("class", NULL, NULL);
	if (!class_kset)
		return -ENOMEM;
	return 0;
}

EXPORT_SYMBOL_GPL(class_create_file_ns);
EXPORT_SYMBOL_GPL(class_remove_file_ns);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_destroy);

EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);