Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/drivers/base/class.c

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

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