xref: /linux/drivers/base/core.c (revision 045ddc8991698a8e9c5668c6190faa8b5d516dc0)
1 /*
2  * drivers/base/core.c - core driver model code (device registration, etc)
3  *
4  * Copyright (c) 2002-3 Patrick Mochel
5  * Copyright (c) 2002-3 Open Source Development Labs
6  * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
7  * Copyright (c) 2006 Novell, Inc.
8  *
9  * This file is released under the GPLv2
10  *
11  */
12 
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/string.h>
19 #include <linux/kdev_t.h>
20 #include <linux/notifier.h>
21 #include <linux/genhd.h>
22 #include <linux/kallsyms.h>
23 #include <linux/mutex.h>
24 #include <linux/async.h>
25 #include <linux/pm_runtime.h>
26 
27 #include "base.h"
28 #include "power/power.h"
29 
30 #ifdef CONFIG_SYSFS_DEPRECATED
31 #ifdef CONFIG_SYSFS_DEPRECATED_V2
32 long sysfs_deprecated = 1;
33 #else
34 long sysfs_deprecated = 0;
35 #endif
36 static __init int sysfs_deprecated_setup(char *arg)
37 {
38 	return strict_strtol(arg, 10, &sysfs_deprecated);
39 }
40 early_param("sysfs.deprecated", sysfs_deprecated_setup);
41 #endif
42 
43 int (*platform_notify)(struct device *dev) = NULL;
44 int (*platform_notify_remove)(struct device *dev) = NULL;
45 static struct kobject *dev_kobj;
46 struct kobject *sysfs_dev_char_kobj;
47 struct kobject *sysfs_dev_block_kobj;
48 
49 #ifdef CONFIG_BLOCK
50 static inline int device_is_not_partition(struct device *dev)
51 {
52 	return !(dev->type == &part_type);
53 }
54 #else
55 static inline int device_is_not_partition(struct device *dev)
56 {
57 	return 1;
58 }
59 #endif
60 
61 /**
62  * dev_driver_string - Return a device's driver name, if at all possible
63  * @dev: struct device to get the name of
64  *
65  * Will return the device's driver's name if it is bound to a device.  If
66  * the device is not bound to a device, it will return the name of the bus
67  * it is attached to.  If it is not attached to a bus either, an empty
68  * string will be returned.
69  */
70 const char *dev_driver_string(const struct device *dev)
71 {
72 	struct device_driver *drv;
73 
74 	/* dev->driver can change to NULL underneath us because of unbinding,
75 	 * so be careful about accessing it.  dev->bus and dev->class should
76 	 * never change once they are set, so they don't need special care.
77 	 */
78 	drv = ACCESS_ONCE(dev->driver);
79 	return drv ? drv->name :
80 			(dev->bus ? dev->bus->name :
81 			(dev->class ? dev->class->name : ""));
82 }
83 EXPORT_SYMBOL(dev_driver_string);
84 
85 #define to_dev(obj) container_of(obj, struct device, kobj)
86 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
87 
88 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
89 			     char *buf)
90 {
91 	struct device_attribute *dev_attr = to_dev_attr(attr);
92 	struct device *dev = to_dev(kobj);
93 	ssize_t ret = -EIO;
94 
95 	if (dev_attr->show)
96 		ret = dev_attr->show(dev, dev_attr, buf);
97 	if (ret >= (ssize_t)PAGE_SIZE) {
98 		print_symbol("dev_attr_show: %s returned bad count\n",
99 				(unsigned long)dev_attr->show);
100 	}
101 	return ret;
102 }
103 
104 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
105 			      const char *buf, size_t count)
106 {
107 	struct device_attribute *dev_attr = to_dev_attr(attr);
108 	struct device *dev = to_dev(kobj);
109 	ssize_t ret = -EIO;
110 
111 	if (dev_attr->store)
112 		ret = dev_attr->store(dev, dev_attr, buf, count);
113 	return ret;
114 }
115 
116 static const struct sysfs_ops dev_sysfs_ops = {
117 	.show	= dev_attr_show,
118 	.store	= dev_attr_store,
119 };
120 
121 
122 /**
123  *	device_release - free device structure.
124  *	@kobj:	device's kobject.
125  *
126  *	This is called once the reference count for the object
127  *	reaches 0. We forward the call to the device's release
128  *	method, which should handle actually freeing the structure.
129  */
130 static void device_release(struct kobject *kobj)
131 {
132 	struct device *dev = to_dev(kobj);
133 	struct device_private *p = dev->p;
134 
135 	if (dev->release)
136 		dev->release(dev);
137 	else if (dev->type && dev->type->release)
138 		dev->type->release(dev);
139 	else if (dev->class && dev->class->dev_release)
140 		dev->class->dev_release(dev);
141 	else
142 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
143 			"function, it is broken and must be fixed.\n",
144 			dev_name(dev));
145 	kfree(p);
146 }
147 
148 static const void *device_namespace(struct kobject *kobj)
149 {
150 	struct device *dev = to_dev(kobj);
151 	const void *ns = NULL;
152 
153 	if (dev->class && dev->class->ns_type)
154 		ns = dev->class->namespace(dev);
155 
156 	return ns;
157 }
158 
159 static struct kobj_type device_ktype = {
160 	.release	= device_release,
161 	.sysfs_ops	= &dev_sysfs_ops,
162 	.namespace	= device_namespace,
163 };
164 
165 
166 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
167 {
168 	struct kobj_type *ktype = get_ktype(kobj);
169 
170 	if (ktype == &device_ktype) {
171 		struct device *dev = to_dev(kobj);
172 		if (dev->bus)
173 			return 1;
174 		if (dev->class)
175 			return 1;
176 	}
177 	return 0;
178 }
179 
180 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
181 {
182 	struct device *dev = to_dev(kobj);
183 
184 	if (dev->bus)
185 		return dev->bus->name;
186 	if (dev->class)
187 		return dev->class->name;
188 	return NULL;
189 }
190 
191 static int dev_uevent(struct kset *kset, struct kobject *kobj,
192 		      struct kobj_uevent_env *env)
193 {
194 	struct device *dev = to_dev(kobj);
195 	int retval = 0;
196 
197 	/* add device node properties if present */
198 	if (MAJOR(dev->devt)) {
199 		const char *tmp;
200 		const char *name;
201 		mode_t mode = 0;
202 
203 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
204 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
205 		name = device_get_devnode(dev, &mode, &tmp);
206 		if (name) {
207 			add_uevent_var(env, "DEVNAME=%s", name);
208 			kfree(tmp);
209 			if (mode)
210 				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
211 		}
212 	}
213 
214 	if (dev->type && dev->type->name)
215 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
216 
217 	if (dev->driver)
218 		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
219 
220 	/* have the bus specific function add its stuff */
221 	if (dev->bus && dev->bus->uevent) {
222 		retval = dev->bus->uevent(dev, env);
223 		if (retval)
224 			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
225 				 dev_name(dev), __func__, retval);
226 	}
227 
228 	/* have the class specific function add its stuff */
229 	if (dev->class && dev->class->dev_uevent) {
230 		retval = dev->class->dev_uevent(dev, env);
231 		if (retval)
232 			pr_debug("device: '%s': %s: class uevent() "
233 				 "returned %d\n", dev_name(dev),
234 				 __func__, retval);
235 	}
236 
237 	/* have the device type specific function add its stuff */
238 	if (dev->type && dev->type->uevent) {
239 		retval = dev->type->uevent(dev, env);
240 		if (retval)
241 			pr_debug("device: '%s': %s: dev_type uevent() "
242 				 "returned %d\n", dev_name(dev),
243 				 __func__, retval);
244 	}
245 
246 	return retval;
247 }
248 
249 static const struct kset_uevent_ops device_uevent_ops = {
250 	.filter =	dev_uevent_filter,
251 	.name =		dev_uevent_name,
252 	.uevent =	dev_uevent,
253 };
254 
255 static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
256 			   char *buf)
257 {
258 	struct kobject *top_kobj;
259 	struct kset *kset;
260 	struct kobj_uevent_env *env = NULL;
261 	int i;
262 	size_t count = 0;
263 	int retval;
264 
265 	/* search the kset, the device belongs to */
266 	top_kobj = &dev->kobj;
267 	while (!top_kobj->kset && top_kobj->parent)
268 		top_kobj = top_kobj->parent;
269 	if (!top_kobj->kset)
270 		goto out;
271 
272 	kset = top_kobj->kset;
273 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
274 		goto out;
275 
276 	/* respect filter */
277 	if (kset->uevent_ops && kset->uevent_ops->filter)
278 		if (!kset->uevent_ops->filter(kset, &dev->kobj))
279 			goto out;
280 
281 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
282 	if (!env)
283 		return -ENOMEM;
284 
285 	/* let the kset specific function add its keys */
286 	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
287 	if (retval)
288 		goto out;
289 
290 	/* copy keys to file */
291 	for (i = 0; i < env->envp_idx; i++)
292 		count += sprintf(&buf[count], "%s\n", env->envp[i]);
293 out:
294 	kfree(env);
295 	return count;
296 }
297 
298 static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
299 			    const char *buf, size_t count)
300 {
301 	enum kobject_action action;
302 
303 	if (kobject_action_type(buf, count, &action) == 0)
304 		kobject_uevent(&dev->kobj, action);
305 	else
306 		dev_err(dev, "uevent: unknown action-string\n");
307 	return count;
308 }
309 
310 static struct device_attribute uevent_attr =
311 	__ATTR(uevent, S_IRUGO | S_IWUSR, show_uevent, store_uevent);
312 
313 static int device_add_attributes(struct device *dev,
314 				 struct device_attribute *attrs)
315 {
316 	int error = 0;
317 	int i;
318 
319 	if (attrs) {
320 		for (i = 0; attr_name(attrs[i]); i++) {
321 			error = device_create_file(dev, &attrs[i]);
322 			if (error)
323 				break;
324 		}
325 		if (error)
326 			while (--i >= 0)
327 				device_remove_file(dev, &attrs[i]);
328 	}
329 	return error;
330 }
331 
332 static void device_remove_attributes(struct device *dev,
333 				     struct device_attribute *attrs)
334 {
335 	int i;
336 
337 	if (attrs)
338 		for (i = 0; attr_name(attrs[i]); i++)
339 			device_remove_file(dev, &attrs[i]);
340 }
341 
342 static int device_add_bin_attributes(struct device *dev,
343 				     struct bin_attribute *attrs)
344 {
345 	int error = 0;
346 	int i;
347 
348 	if (attrs) {
349 		for (i = 0; attr_name(attrs[i]); i++) {
350 			error = device_create_bin_file(dev, &attrs[i]);
351 			if (error)
352 				break;
353 		}
354 		if (error)
355 			while (--i >= 0)
356 				device_remove_bin_file(dev, &attrs[i]);
357 	}
358 	return error;
359 }
360 
361 static void device_remove_bin_attributes(struct device *dev,
362 					 struct bin_attribute *attrs)
363 {
364 	int i;
365 
366 	if (attrs)
367 		for (i = 0; attr_name(attrs[i]); i++)
368 			device_remove_bin_file(dev, &attrs[i]);
369 }
370 
371 static int device_add_groups(struct device *dev,
372 			     const struct attribute_group **groups)
373 {
374 	int error = 0;
375 	int i;
376 
377 	if (groups) {
378 		for (i = 0; groups[i]; i++) {
379 			error = sysfs_create_group(&dev->kobj, groups[i]);
380 			if (error) {
381 				while (--i >= 0)
382 					sysfs_remove_group(&dev->kobj,
383 							   groups[i]);
384 				break;
385 			}
386 		}
387 	}
388 	return error;
389 }
390 
391 static void device_remove_groups(struct device *dev,
392 				 const struct attribute_group **groups)
393 {
394 	int i;
395 
396 	if (groups)
397 		for (i = 0; groups[i]; i++)
398 			sysfs_remove_group(&dev->kobj, groups[i]);
399 }
400 
401 static int device_add_attrs(struct device *dev)
402 {
403 	struct class *class = dev->class;
404 	const struct device_type *type = dev->type;
405 	int error;
406 
407 	if (class) {
408 		error = device_add_attributes(dev, class->dev_attrs);
409 		if (error)
410 			return error;
411 		error = device_add_bin_attributes(dev, class->dev_bin_attrs);
412 		if (error)
413 			goto err_remove_class_attrs;
414 	}
415 
416 	if (type) {
417 		error = device_add_groups(dev, type->groups);
418 		if (error)
419 			goto err_remove_class_bin_attrs;
420 	}
421 
422 	error = device_add_groups(dev, dev->groups);
423 	if (error)
424 		goto err_remove_type_groups;
425 
426 	return 0;
427 
428  err_remove_type_groups:
429 	if (type)
430 		device_remove_groups(dev, type->groups);
431  err_remove_class_bin_attrs:
432 	if (class)
433 		device_remove_bin_attributes(dev, class->dev_bin_attrs);
434  err_remove_class_attrs:
435 	if (class)
436 		device_remove_attributes(dev, class->dev_attrs);
437 
438 	return error;
439 }
440 
441 static void device_remove_attrs(struct device *dev)
442 {
443 	struct class *class = dev->class;
444 	const struct device_type *type = dev->type;
445 
446 	device_remove_groups(dev, dev->groups);
447 
448 	if (type)
449 		device_remove_groups(dev, type->groups);
450 
451 	if (class) {
452 		device_remove_attributes(dev, class->dev_attrs);
453 		device_remove_bin_attributes(dev, class->dev_bin_attrs);
454 	}
455 }
456 
457 
458 static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
459 			char *buf)
460 {
461 	return print_dev_t(buf, dev->devt);
462 }
463 
464 static struct device_attribute devt_attr =
465 	__ATTR(dev, S_IRUGO, show_dev, NULL);
466 
467 /* kset to create /sys/devices/  */
468 struct kset *devices_kset;
469 
470 /**
471  * device_create_file - create sysfs attribute file for device.
472  * @dev: device.
473  * @attr: device attribute descriptor.
474  */
475 int device_create_file(struct device *dev,
476 		       const struct device_attribute *attr)
477 {
478 	int error = 0;
479 	if (dev)
480 		error = sysfs_create_file(&dev->kobj, &attr->attr);
481 	return error;
482 }
483 
484 /**
485  * device_remove_file - remove sysfs attribute file.
486  * @dev: device.
487  * @attr: device attribute descriptor.
488  */
489 void device_remove_file(struct device *dev,
490 			const struct device_attribute *attr)
491 {
492 	if (dev)
493 		sysfs_remove_file(&dev->kobj, &attr->attr);
494 }
495 
496 /**
497  * device_create_bin_file - create sysfs binary attribute file for device.
498  * @dev: device.
499  * @attr: device binary attribute descriptor.
500  */
501 int device_create_bin_file(struct device *dev,
502 			   const struct bin_attribute *attr)
503 {
504 	int error = -EINVAL;
505 	if (dev)
506 		error = sysfs_create_bin_file(&dev->kobj, attr);
507 	return error;
508 }
509 EXPORT_SYMBOL_GPL(device_create_bin_file);
510 
511 /**
512  * device_remove_bin_file - remove sysfs binary attribute file
513  * @dev: device.
514  * @attr: device binary attribute descriptor.
515  */
516 void device_remove_bin_file(struct device *dev,
517 			    const struct bin_attribute *attr)
518 {
519 	if (dev)
520 		sysfs_remove_bin_file(&dev->kobj, attr);
521 }
522 EXPORT_SYMBOL_GPL(device_remove_bin_file);
523 
524 /**
525  * device_schedule_callback_owner - helper to schedule a callback for a device
526  * @dev: device.
527  * @func: callback function to invoke later.
528  * @owner: module owning the callback routine
529  *
530  * Attribute methods must not unregister themselves or their parent device
531  * (which would amount to the same thing).  Attempts to do so will deadlock,
532  * since unregistration is mutually exclusive with driver callbacks.
533  *
534  * Instead methods can call this routine, which will attempt to allocate
535  * and schedule a workqueue request to call back @func with @dev as its
536  * argument in the workqueue's process context.  @dev will be pinned until
537  * @func returns.
538  *
539  * This routine is usually called via the inline device_schedule_callback(),
540  * which automatically sets @owner to THIS_MODULE.
541  *
542  * Returns 0 if the request was submitted, -ENOMEM if storage could not
543  * be allocated, -ENODEV if a reference to @owner isn't available.
544  *
545  * NOTE: This routine won't work if CONFIG_SYSFS isn't set!  It uses an
546  * underlying sysfs routine (since it is intended for use by attribute
547  * methods), and if sysfs isn't available you'll get nothing but -ENOSYS.
548  */
549 int device_schedule_callback_owner(struct device *dev,
550 		void (*func)(struct device *), struct module *owner)
551 {
552 	return sysfs_schedule_callback(&dev->kobj,
553 			(void (*)(void *)) func, dev, owner);
554 }
555 EXPORT_SYMBOL_GPL(device_schedule_callback_owner);
556 
557 static void klist_children_get(struct klist_node *n)
558 {
559 	struct device_private *p = to_device_private_parent(n);
560 	struct device *dev = p->device;
561 
562 	get_device(dev);
563 }
564 
565 static void klist_children_put(struct klist_node *n)
566 {
567 	struct device_private *p = to_device_private_parent(n);
568 	struct device *dev = p->device;
569 
570 	put_device(dev);
571 }
572 
573 /**
574  * device_initialize - init device structure.
575  * @dev: device.
576  *
577  * This prepares the device for use by other layers by initializing
578  * its fields.
579  * It is the first half of device_register(), if called by
580  * that function, though it can also be called separately, so one
581  * may use @dev's fields. In particular, get_device()/put_device()
582  * may be used for reference counting of @dev after calling this
583  * function.
584  *
585  * NOTE: Use put_device() to give up your reference instead of freeing
586  * @dev directly once you have called this function.
587  */
588 void device_initialize(struct device *dev)
589 {
590 	dev->kobj.kset = devices_kset;
591 	kobject_init(&dev->kobj, &device_ktype);
592 	INIT_LIST_HEAD(&dev->dma_pools);
593 	mutex_init(&dev->mutex);
594 	lockdep_set_novalidate_class(&dev->mutex);
595 	spin_lock_init(&dev->devres_lock);
596 	INIT_LIST_HEAD(&dev->devres_head);
597 	device_pm_init(dev);
598 	set_dev_node(dev, -1);
599 }
600 
601 static struct kobject *virtual_device_parent(struct device *dev)
602 {
603 	static struct kobject *virtual_dir = NULL;
604 
605 	if (!virtual_dir)
606 		virtual_dir = kobject_create_and_add("virtual",
607 						     &devices_kset->kobj);
608 
609 	return virtual_dir;
610 }
611 
612 struct class_dir {
613 	struct kobject kobj;
614 	struct class *class;
615 };
616 
617 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
618 
619 static void class_dir_release(struct kobject *kobj)
620 {
621 	struct class_dir *dir = to_class_dir(kobj);
622 	kfree(dir);
623 }
624 
625 static const
626 struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
627 {
628 	struct class_dir *dir = to_class_dir(kobj);
629 	return dir->class->ns_type;
630 }
631 
632 static struct kobj_type class_dir_ktype = {
633 	.release	= class_dir_release,
634 	.sysfs_ops	= &kobj_sysfs_ops,
635 	.child_ns_type	= class_dir_child_ns_type
636 };
637 
638 static struct kobject *
639 class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
640 {
641 	struct class_dir *dir;
642 	int retval;
643 
644 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
645 	if (!dir)
646 		return NULL;
647 
648 	dir->class = class;
649 	kobject_init(&dir->kobj, &class_dir_ktype);
650 
651 	dir->kobj.kset = &class->p->glue_dirs;
652 
653 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
654 	if (retval < 0) {
655 		kobject_put(&dir->kobj);
656 		return NULL;
657 	}
658 	return &dir->kobj;
659 }
660 
661 
662 static struct kobject *get_device_parent(struct device *dev,
663 					 struct device *parent)
664 {
665 	if (dev->class) {
666 		static DEFINE_MUTEX(gdp_mutex);
667 		struct kobject *kobj = NULL;
668 		struct kobject *parent_kobj;
669 		struct kobject *k;
670 
671 #ifdef CONFIG_BLOCK
672 		/* block disks show up in /sys/block */
673 		if (sysfs_deprecated && dev->class == &block_class) {
674 			if (parent && parent->class == &block_class)
675 				return &parent->kobj;
676 			return &block_class.p->subsys.kobj;
677 		}
678 #endif
679 
680 		/*
681 		 * If we have no parent, we live in "virtual".
682 		 * Class-devices with a non class-device as parent, live
683 		 * in a "glue" directory to prevent namespace collisions.
684 		 */
685 		if (parent == NULL)
686 			parent_kobj = virtual_device_parent(dev);
687 		else if (parent->class && !dev->class->ns_type)
688 			return &parent->kobj;
689 		else
690 			parent_kobj = &parent->kobj;
691 
692 		mutex_lock(&gdp_mutex);
693 
694 		/* find our class-directory at the parent and reference it */
695 		spin_lock(&dev->class->p->glue_dirs.list_lock);
696 		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
697 			if (k->parent == parent_kobj) {
698 				kobj = kobject_get(k);
699 				break;
700 			}
701 		spin_unlock(&dev->class->p->glue_dirs.list_lock);
702 		if (kobj) {
703 			mutex_unlock(&gdp_mutex);
704 			return kobj;
705 		}
706 
707 		/* or create a new class-directory at the parent device */
708 		k = class_dir_create_and_add(dev->class, parent_kobj);
709 		/* do not emit an uevent for this simple "glue" directory */
710 		mutex_unlock(&gdp_mutex);
711 		return k;
712 	}
713 
714 	if (parent)
715 		return &parent->kobj;
716 	return NULL;
717 }
718 
719 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
720 {
721 	/* see if we live in a "glue" directory */
722 	if (!glue_dir || !dev->class ||
723 	    glue_dir->kset != &dev->class->p->glue_dirs)
724 		return;
725 
726 	kobject_put(glue_dir);
727 }
728 
729 static void cleanup_device_parent(struct device *dev)
730 {
731 	cleanup_glue_dir(dev, dev->kobj.parent);
732 }
733 
734 static void setup_parent(struct device *dev, struct device *parent)
735 {
736 	struct kobject *kobj;
737 	kobj = get_device_parent(dev, parent);
738 	if (kobj)
739 		dev->kobj.parent = kobj;
740 }
741 
742 static int device_add_class_symlinks(struct device *dev)
743 {
744 	int error;
745 
746 	if (!dev->class)
747 		return 0;
748 
749 	error = sysfs_create_link(&dev->kobj,
750 				  &dev->class->p->subsys.kobj,
751 				  "subsystem");
752 	if (error)
753 		goto out;
754 
755 	if (dev->parent && device_is_not_partition(dev)) {
756 		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
757 					  "device");
758 		if (error)
759 			goto out_subsys;
760 	}
761 
762 #ifdef CONFIG_BLOCK
763 	/* /sys/block has directories and does not need symlinks */
764 	if (sysfs_deprecated && dev->class == &block_class)
765 		return 0;
766 #endif
767 
768 	/* link in the class directory pointing to the device */
769 	error = sysfs_create_link(&dev->class->p->subsys.kobj,
770 				  &dev->kobj, dev_name(dev));
771 	if (error)
772 		goto out_device;
773 
774 	return 0;
775 
776 out_device:
777 	sysfs_remove_link(&dev->kobj, "device");
778 
779 out_subsys:
780 	sysfs_remove_link(&dev->kobj, "subsystem");
781 out:
782 	return error;
783 }
784 
785 static void device_remove_class_symlinks(struct device *dev)
786 {
787 	if (!dev->class)
788 		return;
789 
790 	if (dev->parent && device_is_not_partition(dev))
791 		sysfs_remove_link(&dev->kobj, "device");
792 	sysfs_remove_link(&dev->kobj, "subsystem");
793 #ifdef CONFIG_BLOCK
794 	if (sysfs_deprecated && dev->class == &block_class)
795 		return;
796 #endif
797 	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
798 }
799 
800 /**
801  * dev_set_name - set a device name
802  * @dev: device
803  * @fmt: format string for the device's name
804  */
805 int dev_set_name(struct device *dev, const char *fmt, ...)
806 {
807 	va_list vargs;
808 	int err;
809 
810 	va_start(vargs, fmt);
811 	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
812 	va_end(vargs);
813 	return err;
814 }
815 EXPORT_SYMBOL_GPL(dev_set_name);
816 
817 /**
818  * device_to_dev_kobj - select a /sys/dev/ directory for the device
819  * @dev: device
820  *
821  * By default we select char/ for new entries.  Setting class->dev_obj
822  * to NULL prevents an entry from being created.  class->dev_kobj must
823  * be set (or cleared) before any devices are registered to the class
824  * otherwise device_create_sys_dev_entry() and
825  * device_remove_sys_dev_entry() will disagree about the the presence
826  * of the link.
827  */
828 static struct kobject *device_to_dev_kobj(struct device *dev)
829 {
830 	struct kobject *kobj;
831 
832 	if (dev->class)
833 		kobj = dev->class->dev_kobj;
834 	else
835 		kobj = sysfs_dev_char_kobj;
836 
837 	return kobj;
838 }
839 
840 static int device_create_sys_dev_entry(struct device *dev)
841 {
842 	struct kobject *kobj = device_to_dev_kobj(dev);
843 	int error = 0;
844 	char devt_str[15];
845 
846 	if (kobj) {
847 		format_dev_t(devt_str, dev->devt);
848 		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
849 	}
850 
851 	return error;
852 }
853 
854 static void device_remove_sys_dev_entry(struct device *dev)
855 {
856 	struct kobject *kobj = device_to_dev_kobj(dev);
857 	char devt_str[15];
858 
859 	if (kobj) {
860 		format_dev_t(devt_str, dev->devt);
861 		sysfs_remove_link(kobj, devt_str);
862 	}
863 }
864 
865 int device_private_init(struct device *dev)
866 {
867 	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
868 	if (!dev->p)
869 		return -ENOMEM;
870 	dev->p->device = dev;
871 	klist_init(&dev->p->klist_children, klist_children_get,
872 		   klist_children_put);
873 	return 0;
874 }
875 
876 /**
877  * device_add - add device to device hierarchy.
878  * @dev: device.
879  *
880  * This is part 2 of device_register(), though may be called
881  * separately _iff_ device_initialize() has been called separately.
882  *
883  * This adds @dev to the kobject hierarchy via kobject_add(), adds it
884  * to the global and sibling lists for the device, then
885  * adds it to the other relevant subsystems of the driver model.
886  *
887  * NOTE: _Never_ directly free @dev after calling this function, even
888  * if it returned an error! Always use put_device() to give up your
889  * reference instead.
890  */
891 int device_add(struct device *dev)
892 {
893 	struct device *parent = NULL;
894 	struct class_interface *class_intf;
895 	int error = -EINVAL;
896 
897 	dev = get_device(dev);
898 	if (!dev)
899 		goto done;
900 
901 	if (!dev->p) {
902 		error = device_private_init(dev);
903 		if (error)
904 			goto done;
905 	}
906 
907 	/*
908 	 * for statically allocated devices, which should all be converted
909 	 * some day, we need to initialize the name. We prevent reading back
910 	 * the name, and force the use of dev_name()
911 	 */
912 	if (dev->init_name) {
913 		dev_set_name(dev, "%s", dev->init_name);
914 		dev->init_name = NULL;
915 	}
916 
917 	if (!dev_name(dev)) {
918 		error = -EINVAL;
919 		goto name_error;
920 	}
921 
922 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
923 
924 	parent = get_device(dev->parent);
925 	setup_parent(dev, parent);
926 
927 	/* use parent numa_node */
928 	if (parent)
929 		set_dev_node(dev, dev_to_node(parent));
930 
931 	/* first, register with generic layer. */
932 	/* we require the name to be set before, and pass NULL */
933 	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
934 	if (error)
935 		goto Error;
936 
937 	/* notify platform of device entry */
938 	if (platform_notify)
939 		platform_notify(dev);
940 
941 	error = device_create_file(dev, &uevent_attr);
942 	if (error)
943 		goto attrError;
944 
945 	if (MAJOR(dev->devt)) {
946 		error = device_create_file(dev, &devt_attr);
947 		if (error)
948 			goto ueventattrError;
949 
950 		error = device_create_sys_dev_entry(dev);
951 		if (error)
952 			goto devtattrError;
953 
954 		devtmpfs_create_node(dev);
955 	}
956 
957 	error = device_add_class_symlinks(dev);
958 	if (error)
959 		goto SymlinkError;
960 	error = device_add_attrs(dev);
961 	if (error)
962 		goto AttrsError;
963 	error = bus_add_device(dev);
964 	if (error)
965 		goto BusError;
966 	error = dpm_sysfs_add(dev);
967 	if (error)
968 		goto DPMError;
969 	device_pm_add(dev);
970 
971 	/* Notify clients of device addition.  This call must come
972 	 * after dpm_sysf_add() and before kobject_uevent().
973 	 */
974 	if (dev->bus)
975 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
976 					     BUS_NOTIFY_ADD_DEVICE, dev);
977 
978 	kobject_uevent(&dev->kobj, KOBJ_ADD);
979 	bus_probe_device(dev);
980 	if (parent)
981 		klist_add_tail(&dev->p->knode_parent,
982 			       &parent->p->klist_children);
983 
984 	if (dev->class) {
985 		mutex_lock(&dev->class->p->class_mutex);
986 		/* tie the class to the device */
987 		klist_add_tail(&dev->knode_class,
988 			       &dev->class->p->klist_devices);
989 
990 		/* notify any interfaces that the device is here */
991 		list_for_each_entry(class_intf,
992 				    &dev->class->p->class_interfaces, node)
993 			if (class_intf->add_dev)
994 				class_intf->add_dev(dev, class_intf);
995 		mutex_unlock(&dev->class->p->class_mutex);
996 	}
997 done:
998 	put_device(dev);
999 	return error;
1000  DPMError:
1001 	bus_remove_device(dev);
1002  BusError:
1003 	device_remove_attrs(dev);
1004  AttrsError:
1005 	device_remove_class_symlinks(dev);
1006  SymlinkError:
1007 	if (MAJOR(dev->devt))
1008 		devtmpfs_delete_node(dev);
1009 	if (MAJOR(dev->devt))
1010 		device_remove_sys_dev_entry(dev);
1011  devtattrError:
1012 	if (MAJOR(dev->devt))
1013 		device_remove_file(dev, &devt_attr);
1014  ueventattrError:
1015 	device_remove_file(dev, &uevent_attr);
1016  attrError:
1017 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1018 	kobject_del(&dev->kobj);
1019  Error:
1020 	cleanup_device_parent(dev);
1021 	if (parent)
1022 		put_device(parent);
1023 name_error:
1024 	kfree(dev->p);
1025 	dev->p = NULL;
1026 	goto done;
1027 }
1028 
1029 /**
1030  * device_register - register a device with the system.
1031  * @dev: pointer to the device structure
1032  *
1033  * This happens in two clean steps - initialize the device
1034  * and add it to the system. The two steps can be called
1035  * separately, but this is the easiest and most common.
1036  * I.e. you should only call the two helpers separately if
1037  * have a clearly defined need to use and refcount the device
1038  * before it is added to the hierarchy.
1039  *
1040  * NOTE: _Never_ directly free @dev after calling this function, even
1041  * if it returned an error! Always use put_device() to give up the
1042  * reference initialized in this function instead.
1043  */
1044 int device_register(struct device *dev)
1045 {
1046 	device_initialize(dev);
1047 	return device_add(dev);
1048 }
1049 
1050 /**
1051  * get_device - increment reference count for device.
1052  * @dev: device.
1053  *
1054  * This simply forwards the call to kobject_get(), though
1055  * we do take care to provide for the case that we get a NULL
1056  * pointer passed in.
1057  */
1058 struct device *get_device(struct device *dev)
1059 {
1060 	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
1061 }
1062 
1063 /**
1064  * put_device - decrement reference count.
1065  * @dev: device in question.
1066  */
1067 void put_device(struct device *dev)
1068 {
1069 	/* might_sleep(); */
1070 	if (dev)
1071 		kobject_put(&dev->kobj);
1072 }
1073 
1074 /**
1075  * device_del - delete device from system.
1076  * @dev: device.
1077  *
1078  * This is the first part of the device unregistration
1079  * sequence. This removes the device from the lists we control
1080  * from here, has it removed from the other driver model
1081  * subsystems it was added to in device_add(), and removes it
1082  * from the kobject hierarchy.
1083  *
1084  * NOTE: this should be called manually _iff_ device_add() was
1085  * also called manually.
1086  */
1087 void device_del(struct device *dev)
1088 {
1089 	struct device *parent = dev->parent;
1090 	struct class_interface *class_intf;
1091 
1092 	/* Notify clients of device removal.  This call must come
1093 	 * before dpm_sysfs_remove().
1094 	 */
1095 	if (dev->bus)
1096 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1097 					     BUS_NOTIFY_DEL_DEVICE, dev);
1098 	device_pm_remove(dev);
1099 	dpm_sysfs_remove(dev);
1100 	if (parent)
1101 		klist_del(&dev->p->knode_parent);
1102 	if (MAJOR(dev->devt)) {
1103 		devtmpfs_delete_node(dev);
1104 		device_remove_sys_dev_entry(dev);
1105 		device_remove_file(dev, &devt_attr);
1106 	}
1107 	if (dev->class) {
1108 		device_remove_class_symlinks(dev);
1109 
1110 		mutex_lock(&dev->class->p->class_mutex);
1111 		/* notify any interfaces that the device is now gone */
1112 		list_for_each_entry(class_intf,
1113 				    &dev->class->p->class_interfaces, node)
1114 			if (class_intf->remove_dev)
1115 				class_intf->remove_dev(dev, class_intf);
1116 		/* remove the device from the class list */
1117 		klist_del(&dev->knode_class);
1118 		mutex_unlock(&dev->class->p->class_mutex);
1119 	}
1120 	device_remove_file(dev, &uevent_attr);
1121 	device_remove_attrs(dev);
1122 	bus_remove_device(dev);
1123 
1124 	/*
1125 	 * Some platform devices are driven without driver attached
1126 	 * and managed resources may have been acquired.  Make sure
1127 	 * all resources are released.
1128 	 */
1129 	devres_release_all(dev);
1130 
1131 	/* Notify the platform of the removal, in case they
1132 	 * need to do anything...
1133 	 */
1134 	if (platform_notify_remove)
1135 		platform_notify_remove(dev);
1136 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1137 	cleanup_device_parent(dev);
1138 	kobject_del(&dev->kobj);
1139 	put_device(parent);
1140 }
1141 
1142 /**
1143  * device_unregister - unregister device from system.
1144  * @dev: device going away.
1145  *
1146  * We do this in two parts, like we do device_register(). First,
1147  * we remove it from all the subsystems with device_del(), then
1148  * we decrement the reference count via put_device(). If that
1149  * is the final reference count, the device will be cleaned up
1150  * via device_release() above. Otherwise, the structure will
1151  * stick around until the final reference to the device is dropped.
1152  */
1153 void device_unregister(struct device *dev)
1154 {
1155 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1156 	device_del(dev);
1157 	put_device(dev);
1158 }
1159 
1160 static struct device *next_device(struct klist_iter *i)
1161 {
1162 	struct klist_node *n = klist_next(i);
1163 	struct device *dev = NULL;
1164 	struct device_private *p;
1165 
1166 	if (n) {
1167 		p = to_device_private_parent(n);
1168 		dev = p->device;
1169 	}
1170 	return dev;
1171 }
1172 
1173 /**
1174  * device_get_devnode - path of device node file
1175  * @dev: device
1176  * @mode: returned file access mode
1177  * @tmp: possibly allocated string
1178  *
1179  * Return the relative path of a possible device node.
1180  * Non-default names may need to allocate a memory to compose
1181  * a name. This memory is returned in tmp and needs to be
1182  * freed by the caller.
1183  */
1184 const char *device_get_devnode(struct device *dev,
1185 			       mode_t *mode, const char **tmp)
1186 {
1187 	char *s;
1188 
1189 	*tmp = NULL;
1190 
1191 	/* the device type may provide a specific name */
1192 	if (dev->type && dev->type->devnode)
1193 		*tmp = dev->type->devnode(dev, mode);
1194 	if (*tmp)
1195 		return *tmp;
1196 
1197 	/* the class may provide a specific name */
1198 	if (dev->class && dev->class->devnode)
1199 		*tmp = dev->class->devnode(dev, mode);
1200 	if (*tmp)
1201 		return *tmp;
1202 
1203 	/* return name without allocation, tmp == NULL */
1204 	if (strchr(dev_name(dev), '!') == NULL)
1205 		return dev_name(dev);
1206 
1207 	/* replace '!' in the name with '/' */
1208 	*tmp = kstrdup(dev_name(dev), GFP_KERNEL);
1209 	if (!*tmp)
1210 		return NULL;
1211 	while ((s = strchr(*tmp, '!')))
1212 		s[0] = '/';
1213 	return *tmp;
1214 }
1215 
1216 /**
1217  * device_for_each_child - device child iterator.
1218  * @parent: parent struct device.
1219  * @data: data for the callback.
1220  * @fn: function to be called for each device.
1221  *
1222  * Iterate over @parent's child devices, and call @fn for each,
1223  * passing it @data.
1224  *
1225  * We check the return of @fn each time. If it returns anything
1226  * other than 0, we break out and return that value.
1227  */
1228 int device_for_each_child(struct device *parent, void *data,
1229 			  int (*fn)(struct device *dev, void *data))
1230 {
1231 	struct klist_iter i;
1232 	struct device *child;
1233 	int error = 0;
1234 
1235 	if (!parent->p)
1236 		return 0;
1237 
1238 	klist_iter_init(&parent->p->klist_children, &i);
1239 	while ((child = next_device(&i)) && !error)
1240 		error = fn(child, data);
1241 	klist_iter_exit(&i);
1242 	return error;
1243 }
1244 
1245 /**
1246  * device_find_child - device iterator for locating a particular device.
1247  * @parent: parent struct device
1248  * @data: Data to pass to match function
1249  * @match: Callback function to check device
1250  *
1251  * This is similar to the device_for_each_child() function above, but it
1252  * returns a reference to a device that is 'found' for later use, as
1253  * determined by the @match callback.
1254  *
1255  * The callback should return 0 if the device doesn't match and non-zero
1256  * if it does.  If the callback returns non-zero and a reference to the
1257  * current device can be obtained, this function will return to the caller
1258  * and not iterate over any more devices.
1259  */
1260 struct device *device_find_child(struct device *parent, void *data,
1261 				 int (*match)(struct device *dev, void *data))
1262 {
1263 	struct klist_iter i;
1264 	struct device *child;
1265 
1266 	if (!parent)
1267 		return NULL;
1268 
1269 	klist_iter_init(&parent->p->klist_children, &i);
1270 	while ((child = next_device(&i)))
1271 		if (match(child, data) && get_device(child))
1272 			break;
1273 	klist_iter_exit(&i);
1274 	return child;
1275 }
1276 
1277 int __init devices_init(void)
1278 {
1279 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
1280 	if (!devices_kset)
1281 		return -ENOMEM;
1282 	dev_kobj = kobject_create_and_add("dev", NULL);
1283 	if (!dev_kobj)
1284 		goto dev_kobj_err;
1285 	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
1286 	if (!sysfs_dev_block_kobj)
1287 		goto block_kobj_err;
1288 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
1289 	if (!sysfs_dev_char_kobj)
1290 		goto char_kobj_err;
1291 
1292 	return 0;
1293 
1294  char_kobj_err:
1295 	kobject_put(sysfs_dev_block_kobj);
1296  block_kobj_err:
1297 	kobject_put(dev_kobj);
1298  dev_kobj_err:
1299 	kset_unregister(devices_kset);
1300 	return -ENOMEM;
1301 }
1302 
1303 EXPORT_SYMBOL_GPL(device_for_each_child);
1304 EXPORT_SYMBOL_GPL(device_find_child);
1305 
1306 EXPORT_SYMBOL_GPL(device_initialize);
1307 EXPORT_SYMBOL_GPL(device_add);
1308 EXPORT_SYMBOL_GPL(device_register);
1309 
1310 EXPORT_SYMBOL_GPL(device_del);
1311 EXPORT_SYMBOL_GPL(device_unregister);
1312 EXPORT_SYMBOL_GPL(get_device);
1313 EXPORT_SYMBOL_GPL(put_device);
1314 
1315 EXPORT_SYMBOL_GPL(device_create_file);
1316 EXPORT_SYMBOL_GPL(device_remove_file);
1317 
1318 struct root_device {
1319 	struct device dev;
1320 	struct module *owner;
1321 };
1322 
1323 inline struct root_device *to_root_device(struct device *d)
1324 {
1325 	return container_of(d, struct root_device, dev);
1326 }
1327 
1328 static void root_device_release(struct device *dev)
1329 {
1330 	kfree(to_root_device(dev));
1331 }
1332 
1333 /**
1334  * __root_device_register - allocate and register a root device
1335  * @name: root device name
1336  * @owner: owner module of the root device, usually THIS_MODULE
1337  *
1338  * This function allocates a root device and registers it
1339  * using device_register(). In order to free the returned
1340  * device, use root_device_unregister().
1341  *
1342  * Root devices are dummy devices which allow other devices
1343  * to be grouped under /sys/devices. Use this function to
1344  * allocate a root device and then use it as the parent of
1345  * any device which should appear under /sys/devices/{name}
1346  *
1347  * The /sys/devices/{name} directory will also contain a
1348  * 'module' symlink which points to the @owner directory
1349  * in sysfs.
1350  *
1351  * Returns &struct device pointer on success, or ERR_PTR() on error.
1352  *
1353  * Note: You probably want to use root_device_register().
1354  */
1355 struct device *__root_device_register(const char *name, struct module *owner)
1356 {
1357 	struct root_device *root;
1358 	int err = -ENOMEM;
1359 
1360 	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
1361 	if (!root)
1362 		return ERR_PTR(err);
1363 
1364 	err = dev_set_name(&root->dev, "%s", name);
1365 	if (err) {
1366 		kfree(root);
1367 		return ERR_PTR(err);
1368 	}
1369 
1370 	root->dev.release = root_device_release;
1371 
1372 	err = device_register(&root->dev);
1373 	if (err) {
1374 		put_device(&root->dev);
1375 		return ERR_PTR(err);
1376 	}
1377 
1378 #ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
1379 	if (owner) {
1380 		struct module_kobject *mk = &owner->mkobj;
1381 
1382 		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
1383 		if (err) {
1384 			device_unregister(&root->dev);
1385 			return ERR_PTR(err);
1386 		}
1387 		root->owner = owner;
1388 	}
1389 #endif
1390 
1391 	return &root->dev;
1392 }
1393 EXPORT_SYMBOL_GPL(__root_device_register);
1394 
1395 /**
1396  * root_device_unregister - unregister and free a root device
1397  * @dev: device going away
1398  *
1399  * This function unregisters and cleans up a device that was created by
1400  * root_device_register().
1401  */
1402 void root_device_unregister(struct device *dev)
1403 {
1404 	struct root_device *root = to_root_device(dev);
1405 
1406 	if (root->owner)
1407 		sysfs_remove_link(&root->dev.kobj, "module");
1408 
1409 	device_unregister(dev);
1410 }
1411 EXPORT_SYMBOL_GPL(root_device_unregister);
1412 
1413 
1414 static void device_create_release(struct device *dev)
1415 {
1416 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1417 	kfree(dev);
1418 }
1419 
1420 /**
1421  * device_create_vargs - creates a device and registers it with sysfs
1422  * @class: pointer to the struct class that this device should be registered to
1423  * @parent: pointer to the parent struct device of this new device, if any
1424  * @devt: the dev_t for the char device to be added
1425  * @drvdata: the data to be added to the device for callbacks
1426  * @fmt: string for the device's name
1427  * @args: va_list for the device's name
1428  *
1429  * This function can be used by char device classes.  A struct device
1430  * will be created in sysfs, registered to the specified class.
1431  *
1432  * A "dev" file will be created, showing the dev_t for the device, if
1433  * the dev_t is not 0,0.
1434  * If a pointer to a parent struct device is passed in, the newly created
1435  * struct device will be a child of that device in sysfs.
1436  * The pointer to the struct device will be returned from the call.
1437  * Any further sysfs files that might be required can be created using this
1438  * pointer.
1439  *
1440  * Returns &struct device pointer on success, or ERR_PTR() on error.
1441  *
1442  * Note: the struct class passed to this function must have previously
1443  * been created with a call to class_create().
1444  */
1445 struct device *device_create_vargs(struct class *class, struct device *parent,
1446 				   dev_t devt, void *drvdata, const char *fmt,
1447 				   va_list args)
1448 {
1449 	struct device *dev = NULL;
1450 	int retval = -ENODEV;
1451 
1452 	if (class == NULL || IS_ERR(class))
1453 		goto error;
1454 
1455 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1456 	if (!dev) {
1457 		retval = -ENOMEM;
1458 		goto error;
1459 	}
1460 
1461 	dev->devt = devt;
1462 	dev->class = class;
1463 	dev->parent = parent;
1464 	dev->release = device_create_release;
1465 	dev_set_drvdata(dev, drvdata);
1466 
1467 	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
1468 	if (retval)
1469 		goto error;
1470 
1471 	retval = device_register(dev);
1472 	if (retval)
1473 		goto error;
1474 
1475 	return dev;
1476 
1477 error:
1478 	put_device(dev);
1479 	return ERR_PTR(retval);
1480 }
1481 EXPORT_SYMBOL_GPL(device_create_vargs);
1482 
1483 /**
1484  * device_create - creates a device and registers it with sysfs
1485  * @class: pointer to the struct class that this device should be registered to
1486  * @parent: pointer to the parent struct device of this new device, if any
1487  * @devt: the dev_t for the char device to be added
1488  * @drvdata: the data to be added to the device for callbacks
1489  * @fmt: string for the device's name
1490  *
1491  * This function can be used by char device classes.  A struct device
1492  * will be created in sysfs, registered to the specified class.
1493  *
1494  * A "dev" file will be created, showing the dev_t for the device, if
1495  * the dev_t is not 0,0.
1496  * If a pointer to a parent struct device is passed in, the newly created
1497  * struct device will be a child of that device in sysfs.
1498  * The pointer to the struct device will be returned from the call.
1499  * Any further sysfs files that might be required can be created using this
1500  * pointer.
1501  *
1502  * Returns &struct device pointer on success, or ERR_PTR() on error.
1503  *
1504  * Note: the struct class passed to this function must have previously
1505  * been created with a call to class_create().
1506  */
1507 struct device *device_create(struct class *class, struct device *parent,
1508 			     dev_t devt, void *drvdata, const char *fmt, ...)
1509 {
1510 	va_list vargs;
1511 	struct device *dev;
1512 
1513 	va_start(vargs, fmt);
1514 	dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);
1515 	va_end(vargs);
1516 	return dev;
1517 }
1518 EXPORT_SYMBOL_GPL(device_create);
1519 
1520 static int __match_devt(struct device *dev, void *data)
1521 {
1522 	dev_t *devt = data;
1523 
1524 	return dev->devt == *devt;
1525 }
1526 
1527 /**
1528  * device_destroy - removes a device that was created with device_create()
1529  * @class: pointer to the struct class that this device was registered with
1530  * @devt: the dev_t of the device that was previously registered
1531  *
1532  * This call unregisters and cleans up a device that was created with a
1533  * call to device_create().
1534  */
1535 void device_destroy(struct class *class, dev_t devt)
1536 {
1537 	struct device *dev;
1538 
1539 	dev = class_find_device(class, NULL, &devt, __match_devt);
1540 	if (dev) {
1541 		put_device(dev);
1542 		device_unregister(dev);
1543 	}
1544 }
1545 EXPORT_SYMBOL_GPL(device_destroy);
1546 
1547 /**
1548  * device_rename - renames a device
1549  * @dev: the pointer to the struct device to be renamed
1550  * @new_name: the new name of the device
1551  *
1552  * It is the responsibility of the caller to provide mutual
1553  * exclusion between two different calls of device_rename
1554  * on the same device to ensure that new_name is valid and
1555  * won't conflict with other devices.
1556  *
1557  * Note: Don't call this function.  Currently, the networking layer calls this
1558  * function, but that will change.  The following text from Kay Sievers offers
1559  * some insight:
1560  *
1561  * Renaming devices is racy at many levels, symlinks and other stuff are not
1562  * replaced atomically, and you get a "move" uevent, but it's not easy to
1563  * connect the event to the old and new device. Device nodes are not renamed at
1564  * all, there isn't even support for that in the kernel now.
1565  *
1566  * In the meantime, during renaming, your target name might be taken by another
1567  * driver, creating conflicts. Or the old name is taken directly after you
1568  * renamed it -- then you get events for the same DEVPATH, before you even see
1569  * the "move" event. It's just a mess, and nothing new should ever rely on
1570  * kernel device renaming. Besides that, it's not even implemented now for
1571  * other things than (driver-core wise very simple) network devices.
1572  *
1573  * We are currently about to change network renaming in udev to completely
1574  * disallow renaming of devices in the same namespace as the kernel uses,
1575  * because we can't solve the problems properly, that arise with swapping names
1576  * of multiple interfaces without races. Means, renaming of eth[0-9]* will only
1577  * be allowed to some other name than eth[0-9]*, for the aforementioned
1578  * reasons.
1579  *
1580  * Make up a "real" name in the driver before you register anything, or add
1581  * some other attributes for userspace to find the device, or use udev to add
1582  * symlinks -- but never rename kernel devices later, it's a complete mess. We
1583  * don't even want to get into that and try to implement the missing pieces in
1584  * the core. We really have other pieces to fix in the driver core mess. :)
1585  */
1586 int device_rename(struct device *dev, const char *new_name)
1587 {
1588 	char *old_class_name = NULL;
1589 	char *new_class_name = NULL;
1590 	char *old_device_name = NULL;
1591 	int error;
1592 
1593 	dev = get_device(dev);
1594 	if (!dev)
1595 		return -EINVAL;
1596 
1597 	pr_debug("device: '%s': %s: renaming to '%s'\n", dev_name(dev),
1598 		 __func__, new_name);
1599 
1600 	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
1601 	if (!old_device_name) {
1602 		error = -ENOMEM;
1603 		goto out;
1604 	}
1605 
1606 	if (dev->class) {
1607 		error = sysfs_rename_link(&dev->class->p->subsys.kobj,
1608 			&dev->kobj, old_device_name, new_name);
1609 		if (error)
1610 			goto out;
1611 	}
1612 
1613 	error = kobject_rename(&dev->kobj, new_name);
1614 	if (error)
1615 		goto out;
1616 
1617 out:
1618 	put_device(dev);
1619 
1620 	kfree(new_class_name);
1621 	kfree(old_class_name);
1622 	kfree(old_device_name);
1623 
1624 	return error;
1625 }
1626 EXPORT_SYMBOL_GPL(device_rename);
1627 
1628 static int device_move_class_links(struct device *dev,
1629 				   struct device *old_parent,
1630 				   struct device *new_parent)
1631 {
1632 	int error = 0;
1633 
1634 	if (old_parent)
1635 		sysfs_remove_link(&dev->kobj, "device");
1636 	if (new_parent)
1637 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
1638 					  "device");
1639 	return error;
1640 }
1641 
1642 /**
1643  * device_move - moves a device to a new parent
1644  * @dev: the pointer to the struct device to be moved
1645  * @new_parent: the new parent of the device (can by NULL)
1646  * @dpm_order: how to reorder the dpm_list
1647  */
1648 int device_move(struct device *dev, struct device *new_parent,
1649 		enum dpm_order dpm_order)
1650 {
1651 	int error;
1652 	struct device *old_parent;
1653 	struct kobject *new_parent_kobj;
1654 
1655 	dev = get_device(dev);
1656 	if (!dev)
1657 		return -EINVAL;
1658 
1659 	device_pm_lock();
1660 	new_parent = get_device(new_parent);
1661 	new_parent_kobj = get_device_parent(dev, new_parent);
1662 
1663 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
1664 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
1665 	error = kobject_move(&dev->kobj, new_parent_kobj);
1666 	if (error) {
1667 		cleanup_glue_dir(dev, new_parent_kobj);
1668 		put_device(new_parent);
1669 		goto out;
1670 	}
1671 	old_parent = dev->parent;
1672 	dev->parent = new_parent;
1673 	if (old_parent)
1674 		klist_remove(&dev->p->knode_parent);
1675 	if (new_parent) {
1676 		klist_add_tail(&dev->p->knode_parent,
1677 			       &new_parent->p->klist_children);
1678 		set_dev_node(dev, dev_to_node(new_parent));
1679 	}
1680 
1681 	if (!dev->class)
1682 		goto out_put;
1683 	error = device_move_class_links(dev, old_parent, new_parent);
1684 	if (error) {
1685 		/* We ignore errors on cleanup since we're hosed anyway... */
1686 		device_move_class_links(dev, new_parent, old_parent);
1687 		if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
1688 			if (new_parent)
1689 				klist_remove(&dev->p->knode_parent);
1690 			dev->parent = old_parent;
1691 			if (old_parent) {
1692 				klist_add_tail(&dev->p->knode_parent,
1693 					       &old_parent->p->klist_children);
1694 				set_dev_node(dev, dev_to_node(old_parent));
1695 			}
1696 		}
1697 		cleanup_glue_dir(dev, new_parent_kobj);
1698 		put_device(new_parent);
1699 		goto out;
1700 	}
1701 	switch (dpm_order) {
1702 	case DPM_ORDER_NONE:
1703 		break;
1704 	case DPM_ORDER_DEV_AFTER_PARENT:
1705 		device_pm_move_after(dev, new_parent);
1706 		break;
1707 	case DPM_ORDER_PARENT_BEFORE_DEV:
1708 		device_pm_move_before(new_parent, dev);
1709 		break;
1710 	case DPM_ORDER_DEV_LAST:
1711 		device_pm_move_last(dev);
1712 		break;
1713 	}
1714 out_put:
1715 	put_device(old_parent);
1716 out:
1717 	device_pm_unlock();
1718 	put_device(dev);
1719 	return error;
1720 }
1721 EXPORT_SYMBOL_GPL(device_move);
1722 
1723 /**
1724  * device_shutdown - call ->shutdown() on each device to shutdown.
1725  */
1726 void device_shutdown(void)
1727 {
1728 	struct device *dev;
1729 
1730 	spin_lock(&devices_kset->list_lock);
1731 	/*
1732 	 * Walk the devices list backward, shutting down each in turn.
1733 	 * Beware that device unplug events may also start pulling
1734 	 * devices offline, even as the system is shutting down.
1735 	 */
1736 	while (!list_empty(&devices_kset->list)) {
1737 		dev = list_entry(devices_kset->list.prev, struct device,
1738 				kobj.entry);
1739 		get_device(dev);
1740 		/*
1741 		 * Make sure the device is off the kset list, in the
1742 		 * event that dev->*->shutdown() doesn't remove it.
1743 		 */
1744 		list_del_init(&dev->kobj.entry);
1745 		spin_unlock(&devices_kset->list_lock);
1746 		/* Disable all device's runtime power management */
1747 		pm_runtime_disable(dev);
1748 
1749 		if (dev->bus && dev->bus->shutdown) {
1750 			dev_dbg(dev, "shutdown\n");
1751 			dev->bus->shutdown(dev);
1752 		} else if (dev->driver && dev->driver->shutdown) {
1753 			dev_dbg(dev, "shutdown\n");
1754 			dev->driver->shutdown(dev);
1755 		}
1756 		put_device(dev);
1757 
1758 		spin_lock(&devices_kset->list_lock);
1759 	}
1760 	spin_unlock(&devices_kset->list_lock);
1761 	async_synchronize_full();
1762 }
1763 
1764 /*
1765  * Device logging functions
1766  */
1767 
1768 #ifdef CONFIG_PRINTK
1769 
1770 int __dev_printk(const char *level, const struct device *dev,
1771 		 struct va_format *vaf)
1772 {
1773 	if (!dev)
1774 		return printk("%s(NULL device *): %pV", level, vaf);
1775 
1776 	return printk("%s%s %s: %pV",
1777 		      level, dev_driver_string(dev), dev_name(dev), vaf);
1778 }
1779 EXPORT_SYMBOL(__dev_printk);
1780 
1781 int dev_printk(const char *level, const struct device *dev,
1782 	       const char *fmt, ...)
1783 {
1784 	struct va_format vaf;
1785 	va_list args;
1786 	int r;
1787 
1788 	va_start(args, fmt);
1789 
1790 	vaf.fmt = fmt;
1791 	vaf.va = &args;
1792 
1793 	r = __dev_printk(level, dev, &vaf);
1794 	va_end(args);
1795 
1796 	return r;
1797 }
1798 EXPORT_SYMBOL(dev_printk);
1799 
1800 #define define_dev_printk_level(func, kern_level)		\
1801 int func(const struct device *dev, const char *fmt, ...)	\
1802 {								\
1803 	struct va_format vaf;					\
1804 	va_list args;						\
1805 	int r;							\
1806 								\
1807 	va_start(args, fmt);					\
1808 								\
1809 	vaf.fmt = fmt;						\
1810 	vaf.va = &args;						\
1811 								\
1812 	r = __dev_printk(kern_level, dev, &vaf);		\
1813 	va_end(args);						\
1814 								\
1815 	return r;						\
1816 }								\
1817 EXPORT_SYMBOL(func);
1818 
1819 define_dev_printk_level(dev_emerg, KERN_EMERG);
1820 define_dev_printk_level(dev_alert, KERN_ALERT);
1821 define_dev_printk_level(dev_crit, KERN_CRIT);
1822 define_dev_printk_level(dev_err, KERN_ERR);
1823 define_dev_printk_level(dev_warn, KERN_WARNING);
1824 define_dev_printk_level(dev_notice, KERN_NOTICE);
1825 define_dev_printk_level(_dev_info, KERN_INFO);
1826 
1827 #endif
1828