xref: /openbmc/linux/drivers/base/class.c (revision b6dcefde)
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 class_private *cp = to_class(kobj);
31 	ssize_t ret = -EIO;
32 
33 	if (class_attr->show)
34 		ret = class_attr->show(cp->class, 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 class_private *cp = to_class(kobj);
43 	ssize_t ret = -EIO;
44 
45 	if (class_attr->store)
46 		ret = class_attr->store(cp->class, buf, count);
47 	return ret;
48 }
49 
50 static void class_release(struct kobject *kobj)
51 {
52 	struct class_private *cp = to_class(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 struct sysfs_ops class_sysfs_ops = {
67 	.show	= class_attr_show,
68 	.store	= class_attr_store,
69 };
70 
71 static struct kobj_type class_ktype = {
72 	.sysfs_ops	= &class_sysfs_ops,
73 	.release	= class_release,
74 };
75 
76 /* Hotplug events for classes go to the class class_subsys */
77 static struct kset *class_kset;
78 
79 
80 int class_create_file(struct class *cls, const struct class_attribute *attr)
81 {
82 	int error;
83 	if (cls)
84 		error = sysfs_create_file(&cls->p->class_subsys.kobj,
85 					  &attr->attr);
86 	else
87 		error = -EINVAL;
88 	return error;
89 }
90 
91 void class_remove_file(struct class *cls, const struct class_attribute *attr)
92 {
93 	if (cls)
94 		sysfs_remove_file(&cls->p->class_subsys.kobj, &attr->attr);
95 }
96 
97 static struct class *class_get(struct class *cls)
98 {
99 	if (cls)
100 		kset_get(&cls->p->class_subsys);
101 	return cls;
102 }
103 
104 static void class_put(struct class *cls)
105 {
106 	if (cls)
107 		kset_put(&cls->p->class_subsys);
108 }
109 
110 static int add_class_attrs(struct class *cls)
111 {
112 	int i;
113 	int error = 0;
114 
115 	if (cls->class_attrs) {
116 		for (i = 0; attr_name(cls->class_attrs[i]); i++) {
117 			error = class_create_file(cls, &cls->class_attrs[i]);
118 			if (error)
119 				goto error;
120 		}
121 	}
122 done:
123 	return error;
124 error:
125 	while (--i >= 0)
126 		class_remove_file(cls, &cls->class_attrs[i]);
127 	goto done;
128 }
129 
130 static void remove_class_attrs(struct class *cls)
131 {
132 	int i;
133 
134 	if (cls->class_attrs) {
135 		for (i = 0; attr_name(cls->class_attrs[i]); i++)
136 			class_remove_file(cls, &cls->class_attrs[i]);
137 	}
138 }
139 
140 static void klist_class_dev_get(struct klist_node *n)
141 {
142 	struct device *dev = container_of(n, struct device, knode_class);
143 
144 	get_device(dev);
145 }
146 
147 static void klist_class_dev_put(struct klist_node *n)
148 {
149 	struct device *dev = container_of(n, struct device, knode_class);
150 
151 	put_device(dev);
152 }
153 
154 int __class_register(struct class *cls, struct lock_class_key *key)
155 {
156 	struct class_private *cp;
157 	int error;
158 
159 	pr_debug("device class '%s': registering\n", cls->name);
160 
161 	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
162 	if (!cp)
163 		return -ENOMEM;
164 	klist_init(&cp->class_devices, klist_class_dev_get, klist_class_dev_put);
165 	INIT_LIST_HEAD(&cp->class_interfaces);
166 	kset_init(&cp->class_dirs);
167 	__mutex_init(&cp->class_mutex, "struct class mutex", key);
168 	error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
169 	if (error) {
170 		kfree(cp);
171 		return error;
172 	}
173 
174 	/* set the default /sys/dev directory for devices of this class */
175 	if (!cls->dev_kobj)
176 		cls->dev_kobj = sysfs_dev_char_kobj;
177 
178 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
179 	/* let the block class directory show up in the root of sysfs */
180 	if (cls != &block_class)
181 		cp->class_subsys.kobj.kset = class_kset;
182 #else
183 	cp->class_subsys.kobj.kset = class_kset;
184 #endif
185 	cp->class_subsys.kobj.ktype = &class_ktype;
186 	cp->class = cls;
187 	cls->p = cp;
188 
189 	error = kset_register(&cp->class_subsys);
190 	if (error) {
191 		kfree(cp);
192 		return error;
193 	}
194 	error = add_class_attrs(class_get(cls));
195 	class_put(cls);
196 	return error;
197 }
198 EXPORT_SYMBOL_GPL(__class_register);
199 
200 void class_unregister(struct class *cls)
201 {
202 	pr_debug("device class '%s': unregistering\n", cls->name);
203 	remove_class_attrs(cls);
204 	kset_unregister(&cls->p->class_subsys);
205 }
206 
207 static void class_create_release(struct class *cls)
208 {
209 	pr_debug("%s called for %s\n", __func__, cls->name);
210 	kfree(cls);
211 }
212 
213 /**
214  * class_create - create a struct class structure
215  * @owner: pointer to the module that is to "own" this struct class
216  * @name: pointer to a string for the name of this class.
217  * @key: the lock_class_key for this class; used by mutex lock debugging
218  *
219  * This is used to create a struct class pointer that can then be used
220  * in calls to device_create().
221  *
222  * Note, the pointer created here is to be destroyed when finished by
223  * making a call to class_destroy().
224  */
225 struct class *__class_create(struct module *owner, const char *name,
226 			     struct lock_class_key *key)
227 {
228 	struct class *cls;
229 	int retval;
230 
231 	cls = kzalloc(sizeof(*cls), GFP_KERNEL);
232 	if (!cls) {
233 		retval = -ENOMEM;
234 		goto error;
235 	}
236 
237 	cls->name = name;
238 	cls->owner = owner;
239 	cls->class_release = class_create_release;
240 
241 	retval = __class_register(cls, key);
242 	if (retval)
243 		goto error;
244 
245 	return cls;
246 
247 error:
248 	kfree(cls);
249 	return ERR_PTR(retval);
250 }
251 EXPORT_SYMBOL_GPL(__class_create);
252 
253 /**
254  * class_destroy - destroys a struct class structure
255  * @cls: pointer to the struct class that is to be destroyed
256  *
257  * Note, the pointer to be destroyed must have been created with a call
258  * to class_create().
259  */
260 void class_destroy(struct class *cls)
261 {
262 	if ((cls == NULL) || (IS_ERR(cls)))
263 		return;
264 
265 	class_unregister(cls);
266 }
267 
268 #ifdef CONFIG_SYSFS_DEPRECATED
269 char *make_class_name(const char *name, struct kobject *kobj)
270 {
271 	char *class_name;
272 	int size;
273 
274 	size = strlen(name) + strlen(kobject_name(kobj)) + 2;
275 
276 	class_name = kmalloc(size, GFP_KERNEL);
277 	if (!class_name)
278 		return NULL;
279 
280 	strcpy(class_name, name);
281 	strcat(class_name, ":");
282 	strcat(class_name, kobject_name(kobj));
283 	return class_name;
284 }
285 #endif
286 
287 /**
288  * class_dev_iter_init - initialize class device iterator
289  * @iter: class iterator to initialize
290  * @class: the class we wanna iterate over
291  * @start: the device to start iterating from, if any
292  * @type: device_type of the devices to iterate over, NULL for all
293  *
294  * Initialize class iterator @iter such that it iterates over devices
295  * of @class.  If @start is set, the list iteration will start there,
296  * otherwise if it is NULL, the iteration starts at the beginning of
297  * the list.
298  */
299 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
300 			 struct device *start, const struct device_type *type)
301 {
302 	struct klist_node *start_knode = NULL;
303 
304 	if (start)
305 		start_knode = &start->knode_class;
306 	klist_iter_init_node(&class->p->class_devices, &iter->ki, start_knode);
307 	iter->type = type;
308 }
309 EXPORT_SYMBOL_GPL(class_dev_iter_init);
310 
311 /**
312  * class_dev_iter_next - iterate to the next device
313  * @iter: class iterator to proceed
314  *
315  * Proceed @iter to the next device and return it.  Returns NULL if
316  * iteration is complete.
317  *
318  * The returned device is referenced and won't be released till
319  * iterator is proceed to the next device or exited.  The caller is
320  * free to do whatever it wants to do with the device including
321  * calling back into class code.
322  */
323 struct device *class_dev_iter_next(struct class_dev_iter *iter)
324 {
325 	struct klist_node *knode;
326 	struct device *dev;
327 
328 	while (1) {
329 		knode = klist_next(&iter->ki);
330 		if (!knode)
331 			return NULL;
332 		dev = container_of(knode, struct device, knode_class);
333 		if (!iter->type || iter->type == dev->type)
334 			return dev;
335 	}
336 }
337 EXPORT_SYMBOL_GPL(class_dev_iter_next);
338 
339 /**
340  * class_dev_iter_exit - finish iteration
341  * @iter: class iterator to finish
342  *
343  * Finish an iteration.  Always call this function after iteration is
344  * complete whether the iteration ran till the end or not.
345  */
346 void class_dev_iter_exit(struct class_dev_iter *iter)
347 {
348 	klist_iter_exit(&iter->ki);
349 }
350 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
351 
352 /**
353  * class_for_each_device - device iterator
354  * @class: the class we're iterating
355  * @start: the device to start with in the list, if any.
356  * @data: data for the callback
357  * @fn: function to be called for each device
358  *
359  * Iterate over @class's list of devices, and call @fn for each,
360  * passing it @data.  If @start is set, the list iteration will start
361  * there, otherwise if it is NULL, the iteration starts at the
362  * beginning of the list.
363  *
364  * We check the return of @fn each time. If it returns anything
365  * other than 0, we break out and return that value.
366  *
367  * @fn is allowed to do anything including calling back into class
368  * code.  There's no locking restriction.
369  */
370 int class_for_each_device(struct class *class, struct device *start,
371 			  void *data, int (*fn)(struct device *, void *))
372 {
373 	struct class_dev_iter iter;
374 	struct device *dev;
375 	int error = 0;
376 
377 	if (!class)
378 		return -EINVAL;
379 	if (!class->p) {
380 		WARN(1, "%s called for class '%s' before it was initialized",
381 		     __func__, class->name);
382 		return -EINVAL;
383 	}
384 
385 	class_dev_iter_init(&iter, class, start, NULL);
386 	while ((dev = class_dev_iter_next(&iter))) {
387 		error = fn(dev, data);
388 		if (error)
389 			break;
390 	}
391 	class_dev_iter_exit(&iter);
392 
393 	return error;
394 }
395 EXPORT_SYMBOL_GPL(class_for_each_device);
396 
397 /**
398  * class_find_device - device iterator for locating a particular device
399  * @class: the class we're iterating
400  * @start: Device to begin with
401  * @data: data for the match function
402  * @match: function to check device
403  *
404  * This is similar to the class_for_each_dev() function above, but it
405  * returns a reference to a device that is 'found' for later use, as
406  * determined by the @match callback.
407  *
408  * The callback should return 0 if the device doesn't match and non-zero
409  * if it does.  If the callback returns non-zero, this function will
410  * return to the caller and not iterate over any more devices.
411  *
412  * Note, you will need to drop the reference with put_device() after use.
413  *
414  * @fn is allowed to do anything including calling back into class
415  * code.  There's no locking restriction.
416  */
417 struct device *class_find_device(struct class *class, struct device *start,
418 				 void *data,
419 				 int (*match)(struct device *, void *))
420 {
421 	struct class_dev_iter iter;
422 	struct device *dev;
423 
424 	if (!class)
425 		return NULL;
426 	if (!class->p) {
427 		WARN(1, "%s called for class '%s' before it was initialized",
428 		     __func__, class->name);
429 		return NULL;
430 	}
431 
432 	class_dev_iter_init(&iter, class, start, NULL);
433 	while ((dev = class_dev_iter_next(&iter))) {
434 		if (match(dev, data)) {
435 			get_device(dev);
436 			break;
437 		}
438 	}
439 	class_dev_iter_exit(&iter);
440 
441 	return dev;
442 }
443 EXPORT_SYMBOL_GPL(class_find_device);
444 
445 int class_interface_register(struct class_interface *class_intf)
446 {
447 	struct class *parent;
448 	struct class_dev_iter iter;
449 	struct device *dev;
450 
451 	if (!class_intf || !class_intf->class)
452 		return -ENODEV;
453 
454 	parent = class_get(class_intf->class);
455 	if (!parent)
456 		return -EINVAL;
457 
458 	mutex_lock(&parent->p->class_mutex);
459 	list_add_tail(&class_intf->node, &parent->p->class_interfaces);
460 	if (class_intf->add_dev) {
461 		class_dev_iter_init(&iter, parent, NULL, NULL);
462 		while ((dev = class_dev_iter_next(&iter)))
463 			class_intf->add_dev(dev, class_intf);
464 		class_dev_iter_exit(&iter);
465 	}
466 	mutex_unlock(&parent->p->class_mutex);
467 
468 	return 0;
469 }
470 
471 void class_interface_unregister(struct class_interface *class_intf)
472 {
473 	struct class *parent = class_intf->class;
474 	struct class_dev_iter iter;
475 	struct device *dev;
476 
477 	if (!parent)
478 		return;
479 
480 	mutex_lock(&parent->p->class_mutex);
481 	list_del_init(&class_intf->node);
482 	if (class_intf->remove_dev) {
483 		class_dev_iter_init(&iter, parent, NULL, NULL);
484 		while ((dev = class_dev_iter_next(&iter)))
485 			class_intf->remove_dev(dev, class_intf);
486 		class_dev_iter_exit(&iter);
487 	}
488 	mutex_unlock(&parent->p->class_mutex);
489 
490 	class_put(parent);
491 }
492 
493 struct class_compat {
494 	struct kobject *kobj;
495 };
496 
497 /**
498  * class_compat_register - register a compatibility class
499  * @name: the name of the class
500  *
501  * Compatibility class are meant as a temporary user-space compatibility
502  * workaround when converting a family of class devices to a bus devices.
503  */
504 struct class_compat *class_compat_register(const char *name)
505 {
506 	struct class_compat *cls;
507 
508 	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
509 	if (!cls)
510 		return NULL;
511 	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
512 	if (!cls->kobj) {
513 		kfree(cls);
514 		return NULL;
515 	}
516 	return cls;
517 }
518 EXPORT_SYMBOL_GPL(class_compat_register);
519 
520 /**
521  * class_compat_unregister - unregister a compatibility class
522  * @cls: the class to unregister
523  */
524 void class_compat_unregister(struct class_compat *cls)
525 {
526 	kobject_put(cls->kobj);
527 	kfree(cls);
528 }
529 EXPORT_SYMBOL_GPL(class_compat_unregister);
530 
531 /**
532  * class_compat_create_link - create a compatibility class device link to
533  *			      a bus device
534  * @cls: the compatibility class
535  * @dev: the target bus device
536  * @device_link: an optional device to which a "device" link should be created
537  */
538 int class_compat_create_link(struct class_compat *cls, struct device *dev,
539 			     struct device *device_link)
540 {
541 	int error;
542 
543 	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
544 	if (error)
545 		return error;
546 
547 	/*
548 	 * Optionally add a "device" link (typically to the parent), as a
549 	 * class device would have one and we want to provide as much
550 	 * backwards compatibility as possible.
551 	 */
552 	if (device_link) {
553 		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
554 					  "device");
555 		if (error)
556 			sysfs_remove_link(cls->kobj, dev_name(dev));
557 	}
558 
559 	return error;
560 }
561 EXPORT_SYMBOL_GPL(class_compat_create_link);
562 
563 /**
564  * class_compat_remove_link - remove a compatibility class device link to
565  *			      a bus device
566  * @cls: the compatibility class
567  * @dev: the target bus device
568  * @device_link: an optional device to which a "device" link was previously
569  * 		 created
570  */
571 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
572 			      struct device *device_link)
573 {
574 	if (device_link)
575 		sysfs_remove_link(&dev->kobj, "device");
576 	sysfs_remove_link(cls->kobj, dev_name(dev));
577 }
578 EXPORT_SYMBOL_GPL(class_compat_remove_link);
579 
580 int __init classes_init(void)
581 {
582 	class_kset = kset_create_and_add("class", NULL, NULL);
583 	if (!class_kset)
584 		return -ENOMEM;
585 	return 0;
586 }
587 
588 EXPORT_SYMBOL_GPL(class_create_file);
589 EXPORT_SYMBOL_GPL(class_remove_file);
590 EXPORT_SYMBOL_GPL(class_unregister);
591 EXPORT_SYMBOL_GPL(class_destroy);
592 
593 EXPORT_SYMBOL_GPL(class_interface_register);
594 EXPORT_SYMBOL_GPL(class_interface_unregister);
595