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 int __init classes_init(void)
494 {
495 class_kset = kset_create_and_add("class", NULL, NULL);
496 if (!class_kset)
497 return -ENOMEM;
498 return 0;
499 }
500
501 EXPORT_SYMBOL_GPL(class_create_file);
502 EXPORT_SYMBOL_GPL(class_remove_file);
503 EXPORT_SYMBOL_GPL(class_unregister);
504 EXPORT_SYMBOL_GPL(class_destroy);
505
506 EXPORT_SYMBOL_GPL(class_interface_register);
507 EXPORT_SYMBOL_GPL(class_interface_unregister);
508
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