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
 25static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
 26			       char *buf)
 27{
 28	struct class_attribute *class_attr = to_class_attr(attr);
 29	struct subsys_private *cp = to_subsys_private(kobj);
 30	ssize_t ret = -EIO;
 31
 32	if (class_attr->show)
 33		ret = class_attr->show(cp->class, class_attr, buf);
 34	return ret;
 35}
 36
 37static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
 38				const char *buf, size_t count)
 39{
 40	struct class_attribute *class_attr = to_class_attr(attr);
 41	struct subsys_private *cp = to_subsys_private(kobj);
 42	ssize_t ret = -EIO;
 43
 44	if (class_attr->store)
 45		ret = class_attr->store(cp->class, class_attr, buf, count);
 46	return ret;
 47}
 48
 49static void class_release(struct kobject *kobj)
 50{
 51	struct subsys_private *cp = to_subsys_private(kobj);
 52	struct class *class = cp->class;
 53
 54	pr_debug("class '%s': release.\n", class->name);
 55
 56	if (class->class_release)
 57		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	kfree(cp);
 63}
 64
 65static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
 66{
 67	struct subsys_private *cp = to_subsys_private(kobj);
 68	struct class *class = cp->class;
 69
 70	return class->ns_type;
 71}
 72
 73static const struct sysfs_ops class_sysfs_ops = {
 74	.show	   = class_attr_show,
 75	.store	   = class_attr_store,
 76};
 77
 78static 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 */
 85static struct kset *class_kset;
 86
 87
 88int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
 89			 const void *ns)
 90{
 91	int error;
 92
 93	if (cls)
 94		error = sysfs_create_file_ns(&cls->p->subsys.kobj,
 95					     &attr->attr, ns);
 96	else
 97		error = -EINVAL;
 98	return error;
 99}
100
101void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
102			  const void *ns)
103{
104	if (cls)
105		sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
106}
107
108static struct class *class_get(struct class *cls)
109{
110	if (cls)
111		kset_get(&cls->p->subsys);
112	return cls;
113}
114
115static void class_put(struct class *cls)
116{
117	if (cls)
118		kset_put(&cls->p->subsys);
119}
120
121static struct device *klist_class_to_dev(struct klist_node *n)
122{
123	struct device_private *p = to_device_private_class(n);
124	return p->device;
125}
126
127static void klist_class_dev_get(struct klist_node *n)
128{
129	struct device *dev = klist_class_to_dev(n);
130
131	get_device(dev);
132}
133
134static void klist_class_dev_put(struct klist_node *n)
135{
136	struct device *dev = klist_class_to_dev(n);
137
138	put_device(dev);
139}
140
141static int class_add_groups(struct class *cls,
142			    const struct attribute_group **groups)
143{
144	return sysfs_create_groups(&cls->p->subsys.kobj, groups);
145}
146
147static void class_remove_groups(struct class *cls,
148				const struct attribute_group **groups)
149{
150	return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
151}
152
153int __class_register(struct class *cls, struct lock_class_key *key)
154{
155	struct subsys_private *cp;
156	int error;
157
158	pr_debug("device class '%s': registering\n", cls->name);
159
160	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
161	if (!cp)
162		return -ENOMEM;
163	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
164	INIT_LIST_HEAD(&cp->interfaces);
165	kset_init(&cp->glue_dirs);
166	__mutex_init(&cp->mutex, "subsys mutex", key);
167	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
168	if (error) {
169		kfree(cp);
170		return error;
171	}
172
173	/* set the default /sys/dev directory for devices of this class */
174	if (!cls->dev_kobj)
175		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	if (!sysfs_deprecated || cls != &block_class)
180		cp->subsys.kobj.kset = class_kset;
181#else
182	cp->subsys.kobj.kset = class_kset;
183#endif
184	cp->subsys.kobj.ktype = &class_ktype;
185	cp->class = cls;
186	cls->p = cp;
187
188	error = kset_register(&cp->subsys);
189	if (error) {
190		kfree(cp);
191		return error;
192	}
193	error = class_add_groups(class_get(cls), cls->class_groups);
194	class_put(cls);
195	return error;
196}
197EXPORT_SYMBOL_GPL(__class_register);
198
199void class_unregister(struct class *cls)
200{
201	pr_debug("device class '%s': unregistering\n", cls->name);
202	class_remove_groups(cls, cls->class_groups);
203	kset_unregister(&cls->p->subsys);
204}
205
206static void class_create_release(struct class *cls)
207{
208	pr_debug("%s called for %s\n", __func__, cls->name);
209	kfree(cls);
210}
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 */
226struct class *__class_create(struct module *owner, const char *name,
227			     struct lock_class_key *key)
228{
229	struct class *cls;
230	int retval;
231
232	cls = kzalloc(sizeof(*cls), GFP_KERNEL);
233	if (!cls) {
234		retval = -ENOMEM;
235		goto error;
236	}
237
238	cls->name = name;
239	cls->owner = owner;
240	cls->class_release = class_create_release;
241
242	retval = __class_register(cls, key);
243	if (retval)
244		goto error;
245
246	return cls;
247
248error:
249	kfree(cls);
250	return ERR_PTR(retval);
251}
252EXPORT_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 */
261void class_destroy(struct class *cls)
262{
263	if ((cls == NULL) || (IS_ERR(cls)))
264		return;
265
266	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 */
281void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
282			 struct device *start, const struct device_type *type)
283{
284	struct klist_node *start_knode = NULL;
285
286	if (start)
287		start_knode = &start->p->knode_class;
288	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
289	iter->type = type;
290}
291EXPORT_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 */
305struct device *class_dev_iter_next(struct class_dev_iter *iter)
306{
307	struct klist_node *knode;
308	struct device *dev;
309
310	while (1) {
311		knode = klist_next(&iter->ki);
312		if (!knode)
313			return NULL;
314		dev = klist_class_to_dev(knode);
315		if (!iter->type || iter->type == dev->type)
316			return dev;
317	}
318}
319EXPORT_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 */
328void class_dev_iter_exit(struct class_dev_iter *iter)
329{
330	klist_iter_exit(&iter->ki);
331}
332EXPORT_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 */
352int class_for_each_device(struct class *class, struct device *start,
353			  void *data, int (*fn)(struct device *, void *))
354{
355	struct class_dev_iter iter;
356	struct device *dev;
357	int error = 0;
358
359	if (!class)
360		return -EINVAL;
361	if (!class->p) {
362		WARN(1, "%s called for class '%s' before it was initialized",
363		     __func__, class->name);
364		return -EINVAL;
365	}
366
367	class_dev_iter_init(&iter, class, start, NULL);
368	while ((dev = class_dev_iter_next(&iter))) {
369		error = fn(dev, data);
370		if (error)
371			break;
372	}
373	class_dev_iter_exit(&iter);
374
375	return error;
376}
377EXPORT_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 */
399struct device *class_find_device(struct class *class, struct device *start,
400				 const void *data,
401				 int (*match)(struct device *, const void *))
402{
403	struct class_dev_iter iter;
404	struct device *dev;
405
406	if (!class)
407		return NULL;
408	if (!class->p) {
409		WARN(1, "%s called for class '%s' before it was initialized",
410		     __func__, class->name);
411		return NULL;
412	}
413
414	class_dev_iter_init(&iter, class, start, NULL);
415	while ((dev = class_dev_iter_next(&iter))) {
416		if (match(dev, data)) {
417			get_device(dev);
418			break;
419		}
420	}
421	class_dev_iter_exit(&iter);
422
423	return dev;
424}
425EXPORT_SYMBOL_GPL(class_find_device);
426
427int class_interface_register(struct class_interface *class_intf)
428{
429	struct class *parent;
430	struct class_dev_iter iter;
431	struct device *dev;
432
433	if (!class_intf || !class_intf->class)
434		return -ENODEV;
435
436	parent = class_get(class_intf->class);
437	if (!parent)
438		return -EINVAL;
439
440	mutex_lock(&parent->p->mutex);
441	list_add_tail(&class_intf->node, &parent->p->interfaces);
442	if (class_intf->add_dev) {
443		class_dev_iter_init(&iter, parent, NULL, NULL);
444		while ((dev = class_dev_iter_next(&iter)))
445			class_intf->add_dev(dev, class_intf);
446		class_dev_iter_exit(&iter);
447	}
448	mutex_unlock(&parent->p->mutex);
449
450	return 0;
451}
452
453void class_interface_unregister(struct class_interface *class_intf)
454{
455	struct class *parent = class_intf->class;
456	struct class_dev_iter iter;
457	struct device *dev;
458
459	if (!parent)
460		return;
461
462	mutex_lock(&parent->p->mutex);
463	list_del_init(&class_intf->node);
464	if (class_intf->remove_dev) {
465		class_dev_iter_init(&iter, parent, NULL, NULL);
466		while ((dev = class_dev_iter_next(&iter)))
467			class_intf->remove_dev(dev, class_intf);
468		class_dev_iter_exit(&iter);
469	}
470	mutex_unlock(&parent->p->mutex);
471
472	class_put(parent);
473}
474
475ssize_t show_class_attr_string(struct class *class,
476			       struct class_attribute *attr, char *buf)
477{
478	struct class_attribute_string *cs;
479
480	cs = container_of(attr, struct class_attribute_string, attr);
481	return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
482}
483
484EXPORT_SYMBOL_GPL(show_class_attr_string);
485
486struct 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 */
497struct class_compat *class_compat_register(const char *name)
498{
499	struct class_compat *cls;
500
501	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
502	if (!cls)
503		return NULL;
504	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
505	if (!cls->kobj) {
506		kfree(cls);
507		return NULL;
508	}
509	return cls;
510}
511EXPORT_SYMBOL_GPL(class_compat_register);
512
513/**
514 * class_compat_unregister - unregister a compatibility class
515 * @cls: the class to unregister
516 */
517void class_compat_unregister(struct class_compat *cls)
518{
519	kobject_put(cls->kobj);
520	kfree(cls);
521}
522EXPORT_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 */
531int class_compat_create_link(struct class_compat *cls, struct device *dev,
532			     struct device *device_link)
533{
534	int error;
535
536	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
537	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	if (device_link) {
546		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
547					  "device");
548		if (error)
549			sysfs_remove_link(cls->kobj, dev_name(dev));
550	}
551
552	return error;
553}
554EXPORT_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 */
564void class_compat_remove_link(struct class_compat *cls, struct device *dev,
565			      struct device *device_link)
566{
567	if (device_link)
568		sysfs_remove_link(&dev->kobj, "device");
569	sysfs_remove_link(cls->kobj, dev_name(dev));
570}
571EXPORT_SYMBOL_GPL(class_compat_remove_link);
572
573int __init classes_init(void)
574{
575	class_kset = kset_create_and_add("class", NULL, NULL);
576	if (!class_kset)
577		return -ENOMEM;
578	return 0;
579}
580
581EXPORT_SYMBOL_GPL(class_create_file_ns);
582EXPORT_SYMBOL_GPL(class_remove_file_ns);
583EXPORT_SYMBOL_GPL(class_unregister);
584EXPORT_SYMBOL_GPL(class_destroy);
585
586EXPORT_SYMBOL_GPL(class_interface_register);
587EXPORT_SYMBOL_GPL(class_interface_unregister);

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