xref: /openbmc/linux/drivers/base/core.c (revision 4800cd83)
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 
26 #include "base.h"
27 #include "power/power.h"
28 
29 #ifdef CONFIG_SYSFS_DEPRECATED
30 #ifdef CONFIG_SYSFS_DEPRECATED_V2
31 long sysfs_deprecated = 1;
32 #else
33 long sysfs_deprecated = 0;
34 #endif
35 static __init int sysfs_deprecated_setup(char *arg)
36 {
37 	return strict_strtol(arg, 10, &sysfs_deprecated);
38 }
39 early_param("sysfs.deprecated", sysfs_deprecated_setup);
40 #endif
41 
42 int (*platform_notify)(struct device *dev) = NULL;
43 int (*platform_notify_remove)(struct device *dev) = NULL;
44 static struct kobject *dev_kobj;
45 struct kobject *sysfs_dev_char_kobj;
46 struct kobject *sysfs_dev_block_kobj;
47 
48 #ifdef CONFIG_BLOCK
49 static inline int device_is_not_partition(struct device *dev)
50 {
51 	return !(dev->type == &part_type);
52 }
53 #else
54 static inline int device_is_not_partition(struct device *dev)
55 {
56 	return 1;
57 }
58 #endif
59 
60 /**
61  * dev_driver_string - Return a device's driver name, if at all possible
62  * @dev: struct device to get the name of
63  *
64  * Will return the device's driver's name if it is bound to a device.  If
65  * the device is not bound to a device, it will return the name of the bus
66  * it is attached to.  If it is not attached to a bus either, an empty
67  * string will be returned.
68  */
69 const char *dev_driver_string(const struct device *dev)
70 {
71 	struct device_driver *drv;
72 
73 	/* dev->driver can change to NULL underneath us because of unbinding,
74 	 * so be careful about accessing it.  dev->bus and dev->class should
75 	 * never change once they are set, so they don't need special care.
76 	 */
77 	drv = ACCESS_ONCE(dev->driver);
78 	return drv ? drv->name :
79 			(dev->bus ? dev->bus->name :
80 			(dev->class ? dev->class->name : ""));
81 }
82 EXPORT_SYMBOL(dev_driver_string);
83 
84 #define to_dev(obj) container_of(obj, struct device, kobj)
85 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
86 
87 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
88 			     char *buf)
89 {
90 	struct device_attribute *dev_attr = to_dev_attr(attr);
91 	struct device *dev = to_dev(kobj);
92 	ssize_t ret = -EIO;
93 
94 	if (dev_attr->show)
95 		ret = dev_attr->show(dev, dev_attr, buf);
96 	if (ret >= (ssize_t)PAGE_SIZE) {
97 		print_symbol("dev_attr_show: %s returned bad count\n",
98 				(unsigned long)dev_attr->show);
99 	}
100 	return ret;
101 }
102 
103 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
104 			      const char *buf, size_t count)
105 {
106 	struct device_attribute *dev_attr = to_dev_attr(attr);
107 	struct device *dev = to_dev(kobj);
108 	ssize_t ret = -EIO;
109 
110 	if (dev_attr->store)
111 		ret = dev_attr->store(dev, dev_attr, buf, count);
112 	return ret;
113 }
114 
115 static const struct sysfs_ops dev_sysfs_ops = {
116 	.show	= dev_attr_show,
117 	.store	= dev_attr_store,
118 };
119 
120 
121 /**
122  *	device_release - free device structure.
123  *	@kobj:	device's kobject.
124  *
125  *	This is called once the reference count for the object
126  *	reaches 0. We forward the call to the device's release
127  *	method, which should handle actually freeing the structure.
128  */
129 static void device_release(struct kobject *kobj)
130 {
131 	struct device *dev = to_dev(kobj);
132 	struct device_private *p = dev->p;
133 
134 	if (dev->release)
135 		dev->release(dev);
136 	else if (dev->type && dev->type->release)
137 		dev->type->release(dev);
138 	else if (dev->class && dev->class->dev_release)
139 		dev->class->dev_release(dev);
140 	else
141 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
142 			"function, it is broken and must be fixed.\n",
143 			dev_name(dev));
144 	kfree(p);
145 }
146 
147 static const void *device_namespace(struct kobject *kobj)
148 {
149 	struct device *dev = to_dev(kobj);
150 	const void *ns = NULL;
151 
152 	if (dev->class && dev->class->ns_type)
153 		ns = dev->class->namespace(dev);
154 
155 	return ns;
156 }
157 
158 static struct kobj_type device_ktype = {
159 	.release	= device_release,
160 	.sysfs_ops	= &dev_sysfs_ops,
161 	.namespace	= device_namespace,
162 };
163 
164 
165 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
166 {
167 	struct kobj_type *ktype = get_ktype(kobj);
168 
169 	if (ktype == &device_ktype) {
170 		struct device *dev = to_dev(kobj);
171 		if (dev->bus)
172 			return 1;
173 		if (dev->class)
174 			return 1;
175 	}
176 	return 0;
177 }
178 
179 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
180 {
181 	struct device *dev = to_dev(kobj);
182 
183 	if (dev->bus)
184 		return dev->bus->name;
185 	if (dev->class)
186 		return dev->class->name;
187 	return NULL;
188 }
189 
190 static int dev_uevent(struct kset *kset, struct kobject *kobj,
191 		      struct kobj_uevent_env *env)
192 {
193 	struct device *dev = to_dev(kobj);
194 	int retval = 0;
195 
196 	/* add device node properties if present */
197 	if (MAJOR(dev->devt)) {
198 		const char *tmp;
199 		const char *name;
200 		mode_t mode = 0;
201 
202 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
203 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
204 		name = device_get_devnode(dev, &mode, &tmp);
205 		if (name) {
206 			add_uevent_var(env, "DEVNAME=%s", name);
207 			kfree(tmp);
208 			if (mode)
209 				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
210 		}
211 	}
212 
213 	if (dev->type && dev->type->name)
214 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
215 
216 	if (dev->driver)
217 		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
218 
219 	/* have the bus specific function add its stuff */
220 	if (dev->bus && dev->bus->uevent) {
221 		retval = dev->bus->uevent(dev, env);
222 		if (retval)
223 			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
224 				 dev_name(dev), __func__, retval);
225 	}
226 
227 	/* have the class specific function add its stuff */
228 	if (dev->class && dev->class->dev_uevent) {
229 		retval = dev->class->dev_uevent(dev, env);
230 		if (retval)
231 			pr_debug("device: '%s': %s: class uevent() "
232 				 "returned %d\n", dev_name(dev),
233 				 __func__, retval);
234 	}
235 
236 	/* have the device type specific function add its stuff */
237 	if (dev->type && dev->type->uevent) {
238 		retval = dev->type->uevent(dev, env);
239 		if (retval)
240 			pr_debug("device: '%s': %s: dev_type uevent() "
241 				 "returned %d\n", dev_name(dev),
242 				 __func__, retval);
243 	}
244 
245 	return retval;
246 }
247 
248 static const struct kset_uevent_ops device_uevent_ops = {
249 	.filter =	dev_uevent_filter,
250 	.name =		dev_uevent_name,
251 	.uevent =	dev_uevent,
252 };
253 
254 static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
255 			   char *buf)
256 {
257 	struct kobject *top_kobj;
258 	struct kset *kset;
259 	struct kobj_uevent_env *env = NULL;
260 	int i;
261 	size_t count = 0;
262 	int retval;
263 
264 	/* search the kset, the device belongs to */
265 	top_kobj = &dev->kobj;
266 	while (!top_kobj->kset && top_kobj->parent)
267 		top_kobj = top_kobj->parent;
268 	if (!top_kobj->kset)
269 		goto out;
270 
271 	kset = top_kobj->kset;
272 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
273 		goto out;
274 
275 	/* respect filter */
276 	if (kset->uevent_ops && kset->uevent_ops->filter)
277 		if (!kset->uevent_ops->filter(kset, &dev->kobj))
278 			goto out;
279 
280 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
281 	if (!env)
282 		return -ENOMEM;
283 
284 	/* let the kset specific function add its keys */
285 	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
286 	if (retval)
287 		goto out;
288 
289 	/* copy keys to file */
290 	for (i = 0; i < env->envp_idx; i++)
291 		count += sprintf(&buf[count], "%s\n", env->envp[i]);
292 out:
293 	kfree(env);
294 	return count;
295 }
296 
297 static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
298 			    const char *buf, size_t count)
299 {
300 	enum kobject_action action;
301 
302 	if (kobject_action_type(buf, count, &action) == 0)
303 		kobject_uevent(&dev->kobj, action);
304 	else
305 		dev_err(dev, "uevent: unknown action-string\n");
306 	return count;
307 }
308 
309 static struct device_attribute uevent_attr =
310 	__ATTR(uevent, S_IRUGO | S_IWUSR, show_uevent, store_uevent);
311 
312 static int device_add_attributes(struct device *dev,
313 				 struct device_attribute *attrs)
314 {
315 	int error = 0;
316 	int i;
317 
318 	if (attrs) {
319 		for (i = 0; attr_name(attrs[i]); i++) {
320 			error = device_create_file(dev, &attrs[i]);
321 			if (error)
322 				break;
323 		}
324 		if (error)
325 			while (--i >= 0)
326 				device_remove_file(dev, &attrs[i]);
327 	}
328 	return error;
329 }
330 
331 static void device_remove_attributes(struct device *dev,
332 				     struct device_attribute *attrs)
333 {
334 	int i;
335 
336 	if (attrs)
337 		for (i = 0; attr_name(attrs[i]); i++)
338 			device_remove_file(dev, &attrs[i]);
339 }
340 
341 static int device_add_bin_attributes(struct device *dev,
342 				     struct bin_attribute *attrs)
343 {
344 	int error = 0;
345 	int i;
346 
347 	if (attrs) {
348 		for (i = 0; attr_name(attrs[i]); i++) {
349 			error = device_create_bin_file(dev, &attrs[i]);
350 			if (error)
351 				break;
352 		}
353 		if (error)
354 			while (--i >= 0)
355 				device_remove_bin_file(dev, &attrs[i]);
356 	}
357 	return error;
358 }
359 
360 static void device_remove_bin_attributes(struct device *dev,
361 					 struct bin_attribute *attrs)
362 {
363 	int i;
364 
365 	if (attrs)
366 		for (i = 0; attr_name(attrs[i]); i++)
367 			device_remove_bin_file(dev, &attrs[i]);
368 }
369 
370 static int device_add_groups(struct device *dev,
371 			     const struct attribute_group **groups)
372 {
373 	int error = 0;
374 	int i;
375 
376 	if (groups) {
377 		for (i = 0; groups[i]; i++) {
378 			error = sysfs_create_group(&dev->kobj, groups[i]);
379 			if (error) {
380 				while (--i >= 0)
381 					sysfs_remove_group(&dev->kobj,
382 							   groups[i]);
383 				break;
384 			}
385 		}
386 	}
387 	return error;
388 }
389 
390 static void device_remove_groups(struct device *dev,
391 				 const struct attribute_group **groups)
392 {
393 	int i;
394 
395 	if (groups)
396 		for (i = 0; groups[i]; i++)
397 			sysfs_remove_group(&dev->kobj, groups[i]);
398 }
399 
400 static int device_add_attrs(struct device *dev)
401 {
402 	struct class *class = dev->class;
403 	struct device_type *type = dev->type;
404 	int error;
405 
406 	if (class) {
407 		error = device_add_attributes(dev, class->dev_attrs);
408 		if (error)
409 			return error;
410 		error = device_add_bin_attributes(dev, class->dev_bin_attrs);
411 		if (error)
412 			goto err_remove_class_attrs;
413 	}
414 
415 	if (type) {
416 		error = device_add_groups(dev, type->groups);
417 		if (error)
418 			goto err_remove_class_bin_attrs;
419 	}
420 
421 	error = device_add_groups(dev, dev->groups);
422 	if (error)
423 		goto err_remove_type_groups;
424 
425 	return 0;
426 
427  err_remove_type_groups:
428 	if (type)
429 		device_remove_groups(dev, type->groups);
430  err_remove_class_bin_attrs:
431 	if (class)
432 		device_remove_bin_attributes(dev, class->dev_bin_attrs);
433  err_remove_class_attrs:
434 	if (class)
435 		device_remove_attributes(dev, class->dev_attrs);
436 
437 	return error;
438 }
439 
440 static void device_remove_attrs(struct device *dev)
441 {
442 	struct class *class = dev->class;
443 	struct device_type *type = dev->type;
444 
445 	device_remove_groups(dev, dev->groups);
446 
447 	if (type)
448 		device_remove_groups(dev, type->groups);
449 
450 	if (class) {
451 		device_remove_attributes(dev, class->dev_attrs);
452 		device_remove_bin_attributes(dev, class->dev_bin_attrs);
453 	}
454 }
455 
456 
457 static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
458 			char *buf)
459 {
460 	return print_dev_t(buf, dev->devt);
461 }
462 
463 static struct device_attribute devt_attr =
464 	__ATTR(dev, S_IRUGO, show_dev, NULL);
465 
466 /* kset to create /sys/devices/  */
467 struct kset *devices_kset;
468 
469 /**
470  * device_create_file - create sysfs attribute file for device.
471  * @dev: device.
472  * @attr: device attribute descriptor.
473  */
474 int device_create_file(struct device *dev,
475 		       const struct device_attribute *attr)
476 {
477 	int error = 0;
478 	if (dev)
479 		error = sysfs_create_file(&dev->kobj, &attr->attr);
480 	return error;
481 }
482 
483 /**
484  * device_remove_file - remove sysfs attribute file.
485  * @dev: device.
486  * @attr: device attribute descriptor.
487  */
488 void device_remove_file(struct device *dev,
489 			const struct device_attribute *attr)
490 {
491 	if (dev)
492 		sysfs_remove_file(&dev->kobj, &attr->attr);
493 }
494 
495 /**
496  * device_create_bin_file - create sysfs binary attribute file for device.
497  * @dev: device.
498  * @attr: device binary attribute descriptor.
499  */
500 int device_create_bin_file(struct device *dev,
501 			   const struct bin_attribute *attr)
502 {
503 	int error = -EINVAL;
504 	if (dev)
505 		error = sysfs_create_bin_file(&dev->kobj, attr);
506 	return error;
507 }
508 EXPORT_SYMBOL_GPL(device_create_bin_file);
509 
510 /**
511  * device_remove_bin_file - remove sysfs binary attribute file
512  * @dev: device.
513  * @attr: device binary attribute descriptor.
514  */
515 void device_remove_bin_file(struct device *dev,
516 			    const struct bin_attribute *attr)
517 {
518 	if (dev)
519 		sysfs_remove_bin_file(&dev->kobj, attr);
520 }
521 EXPORT_SYMBOL_GPL(device_remove_bin_file);
522 
523 /**
524  * device_schedule_callback_owner - helper to schedule a callback for a device
525  * @dev: device.
526  * @func: callback function to invoke later.
527  * @owner: module owning the callback routine
528  *
529  * Attribute methods must not unregister themselves or their parent device
530  * (which would amount to the same thing).  Attempts to do so will deadlock,
531  * since unregistration is mutually exclusive with driver callbacks.
532  *
533  * Instead methods can call this routine, which will attempt to allocate
534  * and schedule a workqueue request to call back @func with @dev as its
535  * argument in the workqueue's process context.  @dev will be pinned until
536  * @func returns.
537  *
538  * This routine is usually called via the inline device_schedule_callback(),
539  * which automatically sets @owner to THIS_MODULE.
540  *
541  * Returns 0 if the request was submitted, -ENOMEM if storage could not
542  * be allocated, -ENODEV if a reference to @owner isn't available.
543  *
544  * NOTE: This routine won't work if CONFIG_SYSFS isn't set!  It uses an
545  * underlying sysfs routine (since it is intended for use by attribute
546  * methods), and if sysfs isn't available you'll get nothing but -ENOSYS.
547  */
548 int device_schedule_callback_owner(struct device *dev,
549 		void (*func)(struct device *), struct module *owner)
550 {
551 	return sysfs_schedule_callback(&dev->kobj,
552 			(void (*)(void *)) func, dev, owner);
553 }
554 EXPORT_SYMBOL_GPL(device_schedule_callback_owner);
555 
556 static void klist_children_get(struct klist_node *n)
557 {
558 	struct device_private *p = to_device_private_parent(n);
559 	struct device *dev = p->device;
560 
561 	get_device(dev);
562 }
563 
564 static void klist_children_put(struct klist_node *n)
565 {
566 	struct device_private *p = to_device_private_parent(n);
567 	struct device *dev = p->device;
568 
569 	put_device(dev);
570 }
571 
572 /**
573  * device_initialize - init device structure.
574  * @dev: device.
575  *
576  * This prepares the device for use by other layers by initializing
577  * its fields.
578  * It is the first half of device_register(), if called by
579  * that function, though it can also be called separately, so one
580  * may use @dev's fields. In particular, get_device()/put_device()
581  * may be used for reference counting of @dev after calling this
582  * function.
583  *
584  * NOTE: Use put_device() to give up your reference instead of freeing
585  * @dev directly once you have called this function.
586  */
587 void device_initialize(struct device *dev)
588 {
589 	dev->kobj.kset = devices_kset;
590 	kobject_init(&dev->kobj, &device_ktype);
591 	INIT_LIST_HEAD(&dev->dma_pools);
592 	mutex_init(&dev->mutex);
593 	lockdep_set_novalidate_class(&dev->mutex);
594 	spin_lock_init(&dev->devres_lock);
595 	INIT_LIST_HEAD(&dev->devres_head);
596 	device_pm_init(dev);
597 	set_dev_node(dev, -1);
598 }
599 
600 static struct kobject *virtual_device_parent(struct device *dev)
601 {
602 	static struct kobject *virtual_dir = NULL;
603 
604 	if (!virtual_dir)
605 		virtual_dir = kobject_create_and_add("virtual",
606 						     &devices_kset->kobj);
607 
608 	return virtual_dir;
609 }
610 
611 struct class_dir {
612 	struct kobject kobj;
613 	struct class *class;
614 };
615 
616 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
617 
618 static void class_dir_release(struct kobject *kobj)
619 {
620 	struct class_dir *dir = to_class_dir(kobj);
621 	kfree(dir);
622 }
623 
624 static const
625 struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
626 {
627 	struct class_dir *dir = to_class_dir(kobj);
628 	return dir->class->ns_type;
629 }
630 
631 static struct kobj_type class_dir_ktype = {
632 	.release	= class_dir_release,
633 	.sysfs_ops	= &kobj_sysfs_ops,
634 	.child_ns_type	= class_dir_child_ns_type
635 };
636 
637 static struct kobject *
638 class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
639 {
640 	struct class_dir *dir;
641 	int retval;
642 
643 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
644 	if (!dir)
645 		return NULL;
646 
647 	dir->class = class;
648 	kobject_init(&dir->kobj, &class_dir_ktype);
649 
650 	dir->kobj.kset = &class->p->glue_dirs;
651 
652 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
653 	if (retval < 0) {
654 		kobject_put(&dir->kobj);
655 		return NULL;
656 	}
657 	return &dir->kobj;
658 }
659 
660 
661 static struct kobject *get_device_parent(struct device *dev,
662 					 struct device *parent)
663 {
664 	if (dev->class) {
665 		static DEFINE_MUTEX(gdp_mutex);
666 		struct kobject *kobj = NULL;
667 		struct kobject *parent_kobj;
668 		struct kobject *k;
669 
670 #ifdef CONFIG_BLOCK
671 		/* block disks show up in /sys/block */
672 		if (sysfs_deprecated && dev->class == &block_class) {
673 			if (parent && parent->class == &block_class)
674 				return &parent->kobj;
675 			return &block_class.p->subsys.kobj;
676 		}
677 #endif
678 
679 		/*
680 		 * If we have no parent, we live in "virtual".
681 		 * Class-devices with a non class-device as parent, live
682 		 * in a "glue" directory to prevent namespace collisions.
683 		 */
684 		if (parent == NULL)
685 			parent_kobj = virtual_device_parent(dev);
686 		else if (parent->class && !dev->class->ns_type)
687 			return &parent->kobj;
688 		else
689 			parent_kobj = &parent->kobj;
690 
691 		mutex_lock(&gdp_mutex);
692 
693 		/* find our class-directory at the parent and reference it */
694 		spin_lock(&dev->class->p->glue_dirs.list_lock);
695 		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
696 			if (k->parent == parent_kobj) {
697 				kobj = kobject_get(k);
698 				break;
699 			}
700 		spin_unlock(&dev->class->p->glue_dirs.list_lock);
701 		if (kobj) {
702 			mutex_unlock(&gdp_mutex);
703 			return kobj;
704 		}
705 
706 		/* or create a new class-directory at the parent device */
707 		k = class_dir_create_and_add(dev->class, parent_kobj);
708 		/* do not emit an uevent for this simple "glue" directory */
709 		mutex_unlock(&gdp_mutex);
710 		return k;
711 	}
712 
713 	if (parent)
714 		return &parent->kobj;
715 	return NULL;
716 }
717 
718 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
719 {
720 	/* see if we live in a "glue" directory */
721 	if (!glue_dir || !dev->class ||
722 	    glue_dir->kset != &dev->class->p->glue_dirs)
723 		return;
724 
725 	kobject_put(glue_dir);
726 }
727 
728 static void cleanup_device_parent(struct device *dev)
729 {
730 	cleanup_glue_dir(dev, dev->kobj.parent);
731 }
732 
733 static void setup_parent(struct device *dev, struct device *parent)
734 {
735 	struct kobject *kobj;
736 	kobj = get_device_parent(dev, parent);
737 	if (kobj)
738 		dev->kobj.parent = kobj;
739 }
740 
741 static int device_add_class_symlinks(struct device *dev)
742 {
743 	int error;
744 
745 	if (!dev->class)
746 		return 0;
747 
748 	error = sysfs_create_link(&dev->kobj,
749 				  &dev->class->p->subsys.kobj,
750 				  "subsystem");
751 	if (error)
752 		goto out;
753 
754 	if (dev->parent && device_is_not_partition(dev)) {
755 		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
756 					  "device");
757 		if (error)
758 			goto out_subsys;
759 	}
760 
761 #ifdef CONFIG_BLOCK
762 	/* /sys/block has directories and does not need symlinks */
763 	if (sysfs_deprecated && dev->class == &block_class)
764 		return 0;
765 #endif
766 
767 	/* link in the class directory pointing to the device */
768 	error = sysfs_create_link(&dev->class->p->subsys.kobj,
769 				  &dev->kobj, dev_name(dev));
770 	if (error)
771 		goto out_device;
772 
773 	return 0;
774 
775 out_device:
776 	sysfs_remove_link(&dev->kobj, "device");
777 
778 out_subsys:
779 	sysfs_remove_link(&dev->kobj, "subsystem");
780 out:
781 	return error;
782 }
783 
784 static void device_remove_class_symlinks(struct device *dev)
785 {
786 	if (!dev->class)
787 		return;
788 
789 	if (dev->parent && device_is_not_partition(dev))
790 		sysfs_remove_link(&dev->kobj, "device");
791 	sysfs_remove_link(&dev->kobj, "subsystem");
792 #ifdef CONFIG_BLOCK
793 	if (sysfs_deprecated && dev->class == &block_class)
794 		return;
795 #endif
796 	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
797 }
798 
799 /**
800  * dev_set_name - set a device name
801  * @dev: device
802  * @fmt: format string for the device's name
803  */
804 int dev_set_name(struct device *dev, const char *fmt, ...)
805 {
806 	va_list vargs;
807 	int err;
808 
809 	va_start(vargs, fmt);
810 	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
811 	va_end(vargs);
812 	return err;
813 }
814 EXPORT_SYMBOL_GPL(dev_set_name);
815 
816 /**
817  * device_to_dev_kobj - select a /sys/dev/ directory for the device
818  * @dev: device
819  *
820  * By default we select char/ for new entries.  Setting class->dev_obj
821  * to NULL prevents an entry from being created.  class->dev_kobj must
822  * be set (or cleared) before any devices are registered to the class
823  * otherwise device_create_sys_dev_entry() and
824  * device_remove_sys_dev_entry() will disagree about the the presence
825  * of the link.
826  */
827 static struct kobject *device_to_dev_kobj(struct device *dev)
828 {
829 	struct kobject *kobj;
830 
831 	if (dev->class)
832 		kobj = dev->class->dev_kobj;
833 	else
834 		kobj = sysfs_dev_char_kobj;
835 
836 	return kobj;
837 }
838 
839 static int device_create_sys_dev_entry(struct device *dev)
840 {
841 	struct kobject *kobj = device_to_dev_kobj(dev);
842 	int error = 0;
843 	char devt_str[15];
844 
845 	if (kobj) {
846 		format_dev_t(devt_str, dev->devt);
847 		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
848 	}
849 
850 	return error;
851 }
852 
853 static void device_remove_sys_dev_entry(struct device *dev)
854 {
855 	struct kobject *kobj = device_to_dev_kobj(dev);
856 	char devt_str[15];
857 
858 	if (kobj) {
859 		format_dev_t(devt_str, dev->devt);
860 		sysfs_remove_link(kobj, devt_str);
861 	}
862 }
863 
864 int device_private_init(struct device *dev)
865 {
866 	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
867 	if (!dev->p)
868 		return -ENOMEM;
869 	dev->p->device = dev;
870 	klist_init(&dev->p->klist_children, klist_children_get,
871 		   klist_children_put);
872 	return 0;
873 }
874 
875 /**
876  * device_add - add device to device hierarchy.
877  * @dev: device.
878  *
879  * This is part 2 of device_register(), though may be called
880  * separately _iff_ device_initialize() has been called separately.
881  *
882  * This adds @dev to the kobject hierarchy via kobject_add(), adds it
883  * to the global and sibling lists for the device, then
884  * adds it to the other relevant subsystems of the driver model.
885  *
886  * NOTE: _Never_ directly free @dev after calling this function, even
887  * if it returned an error! Always use put_device() to give up your
888  * reference instead.
889  */
890 int device_add(struct device *dev)
891 {
892 	struct device *parent = NULL;
893 	struct class_interface *class_intf;
894 	int error = -EINVAL;
895 
896 	dev = get_device(dev);
897 	if (!dev)
898 		goto done;
899 
900 	if (!dev->p) {
901 		error = device_private_init(dev);
902 		if (error)
903 			goto done;
904 	}
905 
906 	/*
907 	 * for statically allocated devices, which should all be converted
908 	 * some day, we need to initialize the name. We prevent reading back
909 	 * the name, and force the use of dev_name()
910 	 */
911 	if (dev->init_name) {
912 		dev_set_name(dev, "%s", dev->init_name);
913 		dev->init_name = NULL;
914 	}
915 
916 	if (!dev_name(dev)) {
917 		error = -EINVAL;
918 		goto name_error;
919 	}
920 
921 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
922 
923 	parent = get_device(dev->parent);
924 	setup_parent(dev, parent);
925 
926 	/* use parent numa_node */
927 	if (parent)
928 		set_dev_node(dev, dev_to_node(parent));
929 
930 	/* first, register with generic layer. */
931 	/* we require the name to be set before, and pass NULL */
932 	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
933 	if (error)
934 		goto Error;
935 
936 	/* notify platform of device entry */
937 	if (platform_notify)
938 		platform_notify(dev);
939 
940 	error = device_create_file(dev, &uevent_attr);
941 	if (error)
942 		goto attrError;
943 
944 	if (MAJOR(dev->devt)) {
945 		error = device_create_file(dev, &devt_attr);
946 		if (error)
947 			goto ueventattrError;
948 
949 		error = device_create_sys_dev_entry(dev);
950 		if (error)
951 			goto devtattrError;
952 
953 		devtmpfs_create_node(dev);
954 	}
955 
956 	error = device_add_class_symlinks(dev);
957 	if (error)
958 		goto SymlinkError;
959 	error = device_add_attrs(dev);
960 	if (error)
961 		goto AttrsError;
962 	error = bus_add_device(dev);
963 	if (error)
964 		goto BusError;
965 	error = dpm_sysfs_add(dev);
966 	if (error)
967 		goto DPMError;
968 	device_pm_add(dev);
969 
970 	/* Notify clients of device addition.  This call must come
971 	 * after dpm_sysf_add() and before kobject_uevent().
972 	 */
973 	if (dev->bus)
974 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
975 					     BUS_NOTIFY_ADD_DEVICE, dev);
976 
977 	kobject_uevent(&dev->kobj, KOBJ_ADD);
978 	bus_probe_device(dev);
979 	if (parent)
980 		klist_add_tail(&dev->p->knode_parent,
981 			       &parent->p->klist_children);
982 
983 	if (dev->class) {
984 		mutex_lock(&dev->class->p->class_mutex);
985 		/* tie the class to the device */
986 		klist_add_tail(&dev->knode_class,
987 			       &dev->class->p->klist_devices);
988 
989 		/* notify any interfaces that the device is here */
990 		list_for_each_entry(class_intf,
991 				    &dev->class->p->class_interfaces, node)
992 			if (class_intf->add_dev)
993 				class_intf->add_dev(dev, class_intf);
994 		mutex_unlock(&dev->class->p->class_mutex);
995 	}
996 done:
997 	put_device(dev);
998 	return error;
999  DPMError:
1000 	bus_remove_device(dev);
1001  BusError:
1002 	device_remove_attrs(dev);
1003  AttrsError:
1004 	device_remove_class_symlinks(dev);
1005  SymlinkError:
1006 	if (MAJOR(dev->devt))
1007 		devtmpfs_delete_node(dev);
1008 	if (MAJOR(dev->devt))
1009 		device_remove_sys_dev_entry(dev);
1010  devtattrError:
1011 	if (MAJOR(dev->devt))
1012 		device_remove_file(dev, &devt_attr);
1013  ueventattrError:
1014 	device_remove_file(dev, &uevent_attr);
1015  attrError:
1016 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1017 	kobject_del(&dev->kobj);
1018  Error:
1019 	cleanup_device_parent(dev);
1020 	if (parent)
1021 		put_device(parent);
1022 name_error:
1023 	kfree(dev->p);
1024 	dev->p = NULL;
1025 	goto done;
1026 }
1027 
1028 /**
1029  * device_register - register a device with the system.
1030  * @dev: pointer to the device structure
1031  *
1032  * This happens in two clean steps - initialize the device
1033  * and add it to the system. The two steps can be called
1034  * separately, but this is the easiest and most common.
1035  * I.e. you should only call the two helpers separately if
1036  * have a clearly defined need to use and refcount the device
1037  * before it is added to the hierarchy.
1038  *
1039  * NOTE: _Never_ directly free @dev after calling this function, even
1040  * if it returned an error! Always use put_device() to give up the
1041  * reference initialized in this function instead.
1042  */
1043 int device_register(struct device *dev)
1044 {
1045 	device_initialize(dev);
1046 	return device_add(dev);
1047 }
1048 
1049 /**
1050  * get_device - increment reference count for device.
1051  * @dev: device.
1052  *
1053  * This simply forwards the call to kobject_get(), though
1054  * we do take care to provide for the case that we get a NULL
1055  * pointer passed in.
1056  */
1057 struct device *get_device(struct device *dev)
1058 {
1059 	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
1060 }
1061 
1062 /**
1063  * put_device - decrement reference count.
1064  * @dev: device in question.
1065  */
1066 void put_device(struct device *dev)
1067 {
1068 	/* might_sleep(); */
1069 	if (dev)
1070 		kobject_put(&dev->kobj);
1071 }
1072 
1073 /**
1074  * device_del - delete device from system.
1075  * @dev: device.
1076  *
1077  * This is the first part of the device unregistration
1078  * sequence. This removes the device from the lists we control
1079  * from here, has it removed from the other driver model
1080  * subsystems it was added to in device_add(), and removes it
1081  * from the kobject hierarchy.
1082  *
1083  * NOTE: this should be called manually _iff_ device_add() was
1084  * also called manually.
1085  */
1086 void device_del(struct device *dev)
1087 {
1088 	struct device *parent = dev->parent;
1089 	struct class_interface *class_intf;
1090 
1091 	/* Notify clients of device removal.  This call must come
1092 	 * before dpm_sysfs_remove().
1093 	 */
1094 	if (dev->bus)
1095 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1096 					     BUS_NOTIFY_DEL_DEVICE, dev);
1097 	device_pm_remove(dev);
1098 	dpm_sysfs_remove(dev);
1099 	if (parent)
1100 		klist_del(&dev->p->knode_parent);
1101 	if (MAJOR(dev->devt)) {
1102 		devtmpfs_delete_node(dev);
1103 		device_remove_sys_dev_entry(dev);
1104 		device_remove_file(dev, &devt_attr);
1105 	}
1106 	if (dev->class) {
1107 		device_remove_class_symlinks(dev);
1108 
1109 		mutex_lock(&dev->class->p->class_mutex);
1110 		/* notify any interfaces that the device is now gone */
1111 		list_for_each_entry(class_intf,
1112 				    &dev->class->p->class_interfaces, node)
1113 			if (class_intf->remove_dev)
1114 				class_intf->remove_dev(dev, class_intf);
1115 		/* remove the device from the class list */
1116 		klist_del(&dev->knode_class);
1117 		mutex_unlock(&dev->class->p->class_mutex);
1118 	}
1119 	device_remove_file(dev, &uevent_attr);
1120 	device_remove_attrs(dev);
1121 	bus_remove_device(dev);
1122 
1123 	/*
1124 	 * Some platform devices are driven without driver attached
1125 	 * and managed resources may have been acquired.  Make sure
1126 	 * all resources are released.
1127 	 */
1128 	devres_release_all(dev);
1129 
1130 	/* Notify the platform of the removal, in case they
1131 	 * need to do anything...
1132 	 */
1133 	if (platform_notify_remove)
1134 		platform_notify_remove(dev);
1135 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1136 	cleanup_device_parent(dev);
1137 	kobject_del(&dev->kobj);
1138 	put_device(parent);
1139 }
1140 
1141 /**
1142  * device_unregister - unregister device from system.
1143  * @dev: device going away.
1144  *
1145  * We do this in two parts, like we do device_register(). First,
1146  * we remove it from all the subsystems with device_del(), then
1147  * we decrement the reference count via put_device(). If that
1148  * is the final reference count, the device will be cleaned up
1149  * via device_release() above. Otherwise, the structure will
1150  * stick around until the final reference to the device is dropped.
1151  */
1152 void device_unregister(struct device *dev)
1153 {
1154 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1155 	device_del(dev);
1156 	put_device(dev);
1157 }
1158 
1159 static struct device *next_device(struct klist_iter *i)
1160 {
1161 	struct klist_node *n = klist_next(i);
1162 	struct device *dev = NULL;
1163 	struct device_private *p;
1164 
1165 	if (n) {
1166 		p = to_device_private_parent(n);
1167 		dev = p->device;
1168 	}
1169 	return dev;
1170 }
1171 
1172 /**
1173  * device_get_devnode - path of device node file
1174  * @dev: device
1175  * @mode: returned file access mode
1176  * @tmp: possibly allocated string
1177  *
1178  * Return the relative path of a possible device node.
1179  * Non-default names may need to allocate a memory to compose
1180  * a name. This memory is returned in tmp and needs to be
1181  * freed by the caller.
1182  */
1183 const char *device_get_devnode(struct device *dev,
1184 			       mode_t *mode, const char **tmp)
1185 {
1186 	char *s;
1187 
1188 	*tmp = NULL;
1189 
1190 	/* the device type may provide a specific name */
1191 	if (dev->type && dev->type->devnode)
1192 		*tmp = dev->type->devnode(dev, mode);
1193 	if (*tmp)
1194 		return *tmp;
1195 
1196 	/* the class may provide a specific name */
1197 	if (dev->class && dev->class->devnode)
1198 		*tmp = dev->class->devnode(dev, mode);
1199 	if (*tmp)
1200 		return *tmp;
1201 
1202 	/* return name without allocation, tmp == NULL */
1203 	if (strchr(dev_name(dev), '!') == NULL)
1204 		return dev_name(dev);
1205 
1206 	/* replace '!' in the name with '/' */
1207 	*tmp = kstrdup(dev_name(dev), GFP_KERNEL);
1208 	if (!*tmp)
1209 		return NULL;
1210 	while ((s = strchr(*tmp, '!')))
1211 		s[0] = '/';
1212 	return *tmp;
1213 }
1214 
1215 /**
1216  * device_for_each_child - device child iterator.
1217  * @parent: parent struct device.
1218  * @data: data for the callback.
1219  * @fn: function to be called for each device.
1220  *
1221  * Iterate over @parent's child devices, and call @fn for each,
1222  * passing it @data.
1223  *
1224  * We check the return of @fn each time. If it returns anything
1225  * other than 0, we break out and return that value.
1226  */
1227 int device_for_each_child(struct device *parent, void *data,
1228 			  int (*fn)(struct device *dev, void *data))
1229 {
1230 	struct klist_iter i;
1231 	struct device *child;
1232 	int error = 0;
1233 
1234 	if (!parent->p)
1235 		return 0;
1236 
1237 	klist_iter_init(&parent->p->klist_children, &i);
1238 	while ((child = next_device(&i)) && !error)
1239 		error = fn(child, data);
1240 	klist_iter_exit(&i);
1241 	return error;
1242 }
1243 
1244 /**
1245  * device_find_child - device iterator for locating a particular device.
1246  * @parent: parent struct device
1247  * @data: Data to pass to match function
1248  * @match: Callback function to check device
1249  *
1250  * This is similar to the device_for_each_child() function above, but it
1251  * returns a reference to a device that is 'found' for later use, as
1252  * determined by the @match callback.
1253  *
1254  * The callback should return 0 if the device doesn't match and non-zero
1255  * if it does.  If the callback returns non-zero and a reference to the
1256  * current device can be obtained, this function will return to the caller
1257  * and not iterate over any more devices.
1258  */
1259 struct device *device_find_child(struct device *parent, void *data,
1260 				 int (*match)(struct device *dev, void *data))
1261 {
1262 	struct klist_iter i;
1263 	struct device *child;
1264 
1265 	if (!parent)
1266 		return NULL;
1267 
1268 	klist_iter_init(&parent->p->klist_children, &i);
1269 	while ((child = next_device(&i)))
1270 		if (match(child, data) && get_device(child))
1271 			break;
1272 	klist_iter_exit(&i);
1273 	return child;
1274 }
1275 
1276 int __init devices_init(void)
1277 {
1278 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
1279 	if (!devices_kset)
1280 		return -ENOMEM;
1281 	dev_kobj = kobject_create_and_add("dev", NULL);
1282 	if (!dev_kobj)
1283 		goto dev_kobj_err;
1284 	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
1285 	if (!sysfs_dev_block_kobj)
1286 		goto block_kobj_err;
1287 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
1288 	if (!sysfs_dev_char_kobj)
1289 		goto char_kobj_err;
1290 
1291 	return 0;
1292 
1293  char_kobj_err:
1294 	kobject_put(sysfs_dev_block_kobj);
1295  block_kobj_err:
1296 	kobject_put(dev_kobj);
1297  dev_kobj_err:
1298 	kset_unregister(devices_kset);
1299 	return -ENOMEM;
1300 }
1301 
1302 EXPORT_SYMBOL_GPL(device_for_each_child);
1303 EXPORT_SYMBOL_GPL(device_find_child);
1304 
1305 EXPORT_SYMBOL_GPL(device_initialize);
1306 EXPORT_SYMBOL_GPL(device_add);
1307 EXPORT_SYMBOL_GPL(device_register);
1308 
1309 EXPORT_SYMBOL_GPL(device_del);
1310 EXPORT_SYMBOL_GPL(device_unregister);
1311 EXPORT_SYMBOL_GPL(get_device);
1312 EXPORT_SYMBOL_GPL(put_device);
1313 
1314 EXPORT_SYMBOL_GPL(device_create_file);
1315 EXPORT_SYMBOL_GPL(device_remove_file);
1316 
1317 struct root_device
1318 {
1319 	struct device dev;
1320 	struct module *owner;
1321 };
1322 
1323 #define to_root_device(dev) container_of(dev, struct root_device, dev)
1324 
1325 static void root_device_release(struct device *dev)
1326 {
1327 	kfree(to_root_device(dev));
1328 }
1329 
1330 /**
1331  * __root_device_register - allocate and register a root device
1332  * @name: root device name
1333  * @owner: owner module of the root device, usually THIS_MODULE
1334  *
1335  * This function allocates a root device and registers it
1336  * using device_register(). In order to free the returned
1337  * device, use root_device_unregister().
1338  *
1339  * Root devices are dummy devices which allow other devices
1340  * to be grouped under /sys/devices. Use this function to
1341  * allocate a root device and then use it as the parent of
1342  * any device which should appear under /sys/devices/{name}
1343  *
1344  * The /sys/devices/{name} directory will also contain a
1345  * 'module' symlink which points to the @owner directory
1346  * in sysfs.
1347  *
1348  * Returns &struct device pointer on success, or ERR_PTR() on error.
1349  *
1350  * Note: You probably want to use root_device_register().
1351  */
1352 struct device *__root_device_register(const char *name, struct module *owner)
1353 {
1354 	struct root_device *root;
1355 	int err = -ENOMEM;
1356 
1357 	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
1358 	if (!root)
1359 		return ERR_PTR(err);
1360 
1361 	err = dev_set_name(&root->dev, "%s", name);
1362 	if (err) {
1363 		kfree(root);
1364 		return ERR_PTR(err);
1365 	}
1366 
1367 	root->dev.release = root_device_release;
1368 
1369 	err = device_register(&root->dev);
1370 	if (err) {
1371 		put_device(&root->dev);
1372 		return ERR_PTR(err);
1373 	}
1374 
1375 #ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
1376 	if (owner) {
1377 		struct module_kobject *mk = &owner->mkobj;
1378 
1379 		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
1380 		if (err) {
1381 			device_unregister(&root->dev);
1382 			return ERR_PTR(err);
1383 		}
1384 		root->owner = owner;
1385 	}
1386 #endif
1387 
1388 	return &root->dev;
1389 }
1390 EXPORT_SYMBOL_GPL(__root_device_register);
1391 
1392 /**
1393  * root_device_unregister - unregister and free a root device
1394  * @dev: device going away
1395  *
1396  * This function unregisters and cleans up a device that was created by
1397  * root_device_register().
1398  */
1399 void root_device_unregister(struct device *dev)
1400 {
1401 	struct root_device *root = to_root_device(dev);
1402 
1403 	if (root->owner)
1404 		sysfs_remove_link(&root->dev.kobj, "module");
1405 
1406 	device_unregister(dev);
1407 }
1408 EXPORT_SYMBOL_GPL(root_device_unregister);
1409 
1410 
1411 static void device_create_release(struct device *dev)
1412 {
1413 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1414 	kfree(dev);
1415 }
1416 
1417 /**
1418  * device_create_vargs - creates a device and registers it with sysfs
1419  * @class: pointer to the struct class that this device should be registered to
1420  * @parent: pointer to the parent struct device of this new device, if any
1421  * @devt: the dev_t for the char device to be added
1422  * @drvdata: the data to be added to the device for callbacks
1423  * @fmt: string for the device's name
1424  * @args: va_list for the device's name
1425  *
1426  * This function can be used by char device classes.  A struct device
1427  * will be created in sysfs, registered to the specified class.
1428  *
1429  * A "dev" file will be created, showing the dev_t for the device, if
1430  * the dev_t is not 0,0.
1431  * If a pointer to a parent struct device is passed in, the newly created
1432  * struct device will be a child of that device in sysfs.
1433  * The pointer to the struct device will be returned from the call.
1434  * Any further sysfs files that might be required can be created using this
1435  * pointer.
1436  *
1437  * Returns &struct device pointer on success, or ERR_PTR() on error.
1438  *
1439  * Note: the struct class passed to this function must have previously
1440  * been created with a call to class_create().
1441  */
1442 struct device *device_create_vargs(struct class *class, struct device *parent,
1443 				   dev_t devt, void *drvdata, const char *fmt,
1444 				   va_list args)
1445 {
1446 	struct device *dev = NULL;
1447 	int retval = -ENODEV;
1448 
1449 	if (class == NULL || IS_ERR(class))
1450 		goto error;
1451 
1452 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1453 	if (!dev) {
1454 		retval = -ENOMEM;
1455 		goto error;
1456 	}
1457 
1458 	dev->devt = devt;
1459 	dev->class = class;
1460 	dev->parent = parent;
1461 	dev->release = device_create_release;
1462 	dev_set_drvdata(dev, drvdata);
1463 
1464 	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
1465 	if (retval)
1466 		goto error;
1467 
1468 	retval = device_register(dev);
1469 	if (retval)
1470 		goto error;
1471 
1472 	return dev;
1473 
1474 error:
1475 	put_device(dev);
1476 	return ERR_PTR(retval);
1477 }
1478 EXPORT_SYMBOL_GPL(device_create_vargs);
1479 
1480 /**
1481  * device_create - creates a device and registers it with sysfs
1482  * @class: pointer to the struct class that this device should be registered to
1483  * @parent: pointer to the parent struct device of this new device, if any
1484  * @devt: the dev_t for the char device to be added
1485  * @drvdata: the data to be added to the device for callbacks
1486  * @fmt: string for the device's name
1487  *
1488  * This function can be used by char device classes.  A struct device
1489  * will be created in sysfs, registered to the specified class.
1490  *
1491  * A "dev" file will be created, showing the dev_t for the device, if
1492  * the dev_t is not 0,0.
1493  * If a pointer to a parent struct device is passed in, the newly created
1494  * struct device will be a child of that device in sysfs.
1495  * The pointer to the struct device will be returned from the call.
1496  * Any further sysfs files that might be required can be created using this
1497  * pointer.
1498  *
1499  * Returns &struct device pointer on success, or ERR_PTR() on error.
1500  *
1501  * Note: the struct class passed to this function must have previously
1502  * been created with a call to class_create().
1503  */
1504 struct device *device_create(struct class *class, struct device *parent,
1505 			     dev_t devt, void *drvdata, const char *fmt, ...)
1506 {
1507 	va_list vargs;
1508 	struct device *dev;
1509 
1510 	va_start(vargs, fmt);
1511 	dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);
1512 	va_end(vargs);
1513 	return dev;
1514 }
1515 EXPORT_SYMBOL_GPL(device_create);
1516 
1517 static int __match_devt(struct device *dev, void *data)
1518 {
1519 	dev_t *devt = data;
1520 
1521 	return dev->devt == *devt;
1522 }
1523 
1524 /**
1525  * device_destroy - removes a device that was created with device_create()
1526  * @class: pointer to the struct class that this device was registered with
1527  * @devt: the dev_t of the device that was previously registered
1528  *
1529  * This call unregisters and cleans up a device that was created with a
1530  * call to device_create().
1531  */
1532 void device_destroy(struct class *class, dev_t devt)
1533 {
1534 	struct device *dev;
1535 
1536 	dev = class_find_device(class, NULL, &devt, __match_devt);
1537 	if (dev) {
1538 		put_device(dev);
1539 		device_unregister(dev);
1540 	}
1541 }
1542 EXPORT_SYMBOL_GPL(device_destroy);
1543 
1544 /**
1545  * device_rename - renames a device
1546  * @dev: the pointer to the struct device to be renamed
1547  * @new_name: the new name of the device
1548  *
1549  * It is the responsibility of the caller to provide mutual
1550  * exclusion between two different calls of device_rename
1551  * on the same device to ensure that new_name is valid and
1552  * won't conflict with other devices.
1553  *
1554  * "Never use this function, bad things will happen" - gregkh
1555  */
1556 int device_rename(struct device *dev, const char *new_name)
1557 {
1558 	char *old_class_name = NULL;
1559 	char *new_class_name = NULL;
1560 	char *old_device_name = NULL;
1561 	int error;
1562 
1563 	dev = get_device(dev);
1564 	if (!dev)
1565 		return -EINVAL;
1566 
1567 	pr_debug("device: '%s': %s: renaming to '%s'\n", dev_name(dev),
1568 		 __func__, new_name);
1569 
1570 	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
1571 	if (!old_device_name) {
1572 		error = -ENOMEM;
1573 		goto out;
1574 	}
1575 
1576 	if (dev->class) {
1577 		error = sysfs_rename_link(&dev->class->p->subsys.kobj,
1578 			&dev->kobj, old_device_name, new_name);
1579 		if (error)
1580 			goto out;
1581 	}
1582 
1583 	error = kobject_rename(&dev->kobj, new_name);
1584 	if (error)
1585 		goto out;
1586 
1587 out:
1588 	put_device(dev);
1589 
1590 	kfree(new_class_name);
1591 	kfree(old_class_name);
1592 	kfree(old_device_name);
1593 
1594 	return error;
1595 }
1596 EXPORT_SYMBOL_GPL(device_rename);
1597 
1598 static int device_move_class_links(struct device *dev,
1599 				   struct device *old_parent,
1600 				   struct device *new_parent)
1601 {
1602 	int error = 0;
1603 
1604 	if (old_parent)
1605 		sysfs_remove_link(&dev->kobj, "device");
1606 	if (new_parent)
1607 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
1608 					  "device");
1609 	return error;
1610 }
1611 
1612 /**
1613  * device_move - moves a device to a new parent
1614  * @dev: the pointer to the struct device to be moved
1615  * @new_parent: the new parent of the device (can by NULL)
1616  * @dpm_order: how to reorder the dpm_list
1617  */
1618 int device_move(struct device *dev, struct device *new_parent,
1619 		enum dpm_order dpm_order)
1620 {
1621 	int error;
1622 	struct device *old_parent;
1623 	struct kobject *new_parent_kobj;
1624 
1625 	dev = get_device(dev);
1626 	if (!dev)
1627 		return -EINVAL;
1628 
1629 	device_pm_lock();
1630 	new_parent = get_device(new_parent);
1631 	new_parent_kobj = get_device_parent(dev, new_parent);
1632 
1633 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
1634 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
1635 	error = kobject_move(&dev->kobj, new_parent_kobj);
1636 	if (error) {
1637 		cleanup_glue_dir(dev, new_parent_kobj);
1638 		put_device(new_parent);
1639 		goto out;
1640 	}
1641 	old_parent = dev->parent;
1642 	dev->parent = new_parent;
1643 	if (old_parent)
1644 		klist_remove(&dev->p->knode_parent);
1645 	if (new_parent) {
1646 		klist_add_tail(&dev->p->knode_parent,
1647 			       &new_parent->p->klist_children);
1648 		set_dev_node(dev, dev_to_node(new_parent));
1649 	}
1650 
1651 	if (!dev->class)
1652 		goto out_put;
1653 	error = device_move_class_links(dev, old_parent, new_parent);
1654 	if (error) {
1655 		/* We ignore errors on cleanup since we're hosed anyway... */
1656 		device_move_class_links(dev, new_parent, old_parent);
1657 		if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
1658 			if (new_parent)
1659 				klist_remove(&dev->p->knode_parent);
1660 			dev->parent = old_parent;
1661 			if (old_parent) {
1662 				klist_add_tail(&dev->p->knode_parent,
1663 					       &old_parent->p->klist_children);
1664 				set_dev_node(dev, dev_to_node(old_parent));
1665 			}
1666 		}
1667 		cleanup_glue_dir(dev, new_parent_kobj);
1668 		put_device(new_parent);
1669 		goto out;
1670 	}
1671 	switch (dpm_order) {
1672 	case DPM_ORDER_NONE:
1673 		break;
1674 	case DPM_ORDER_DEV_AFTER_PARENT:
1675 		device_pm_move_after(dev, new_parent);
1676 		break;
1677 	case DPM_ORDER_PARENT_BEFORE_DEV:
1678 		device_pm_move_before(new_parent, dev);
1679 		break;
1680 	case DPM_ORDER_DEV_LAST:
1681 		device_pm_move_last(dev);
1682 		break;
1683 	}
1684 out_put:
1685 	put_device(old_parent);
1686 out:
1687 	device_pm_unlock();
1688 	put_device(dev);
1689 	return error;
1690 }
1691 EXPORT_SYMBOL_GPL(device_move);
1692 
1693 /**
1694  * device_shutdown - call ->shutdown() on each device to shutdown.
1695  */
1696 void device_shutdown(void)
1697 {
1698 	struct device *dev;
1699 
1700 	spin_lock(&devices_kset->list_lock);
1701 	/*
1702 	 * Walk the devices list backward, shutting down each in turn.
1703 	 * Beware that device unplug events may also start pulling
1704 	 * devices offline, even as the system is shutting down.
1705 	 */
1706 	while (!list_empty(&devices_kset->list)) {
1707 		dev = list_entry(devices_kset->list.prev, struct device,
1708 				kobj.entry);
1709 		get_device(dev);
1710 		/*
1711 		 * Make sure the device is off the kset list, in the
1712 		 * event that dev->*->shutdown() doesn't remove it.
1713 		 */
1714 		list_del_init(&dev->kobj.entry);
1715 		spin_unlock(&devices_kset->list_lock);
1716 
1717 		if (dev->bus && dev->bus->shutdown) {
1718 			dev_dbg(dev, "shutdown\n");
1719 			dev->bus->shutdown(dev);
1720 		} else if (dev->driver && dev->driver->shutdown) {
1721 			dev_dbg(dev, "shutdown\n");
1722 			dev->driver->shutdown(dev);
1723 		}
1724 		put_device(dev);
1725 
1726 		spin_lock(&devices_kset->list_lock);
1727 	}
1728 	spin_unlock(&devices_kset->list_lock);
1729 	async_synchronize_full();
1730 }
1731 
1732 /*
1733  * Device logging functions
1734  */
1735 
1736 #ifdef CONFIG_PRINTK
1737 
1738 static int __dev_printk(const char *level, const struct device *dev,
1739 			struct va_format *vaf)
1740 {
1741 	if (!dev)
1742 		return printk("%s(NULL device *): %pV", level, vaf);
1743 
1744 	return printk("%s%s %s: %pV",
1745 		      level, dev_driver_string(dev), dev_name(dev), vaf);
1746 }
1747 
1748 int dev_printk(const char *level, const struct device *dev,
1749 	       const char *fmt, ...)
1750 {
1751 	struct va_format vaf;
1752 	va_list args;
1753 	int r;
1754 
1755 	va_start(args, fmt);
1756 
1757 	vaf.fmt = fmt;
1758 	vaf.va = &args;
1759 
1760 	r = __dev_printk(level, dev, &vaf);
1761 	va_end(args);
1762 
1763 	return r;
1764 }
1765 EXPORT_SYMBOL(dev_printk);
1766 
1767 #define define_dev_printk_level(func, kern_level)		\
1768 int func(const struct device *dev, const char *fmt, ...)	\
1769 {								\
1770 	struct va_format vaf;					\
1771 	va_list args;						\
1772 	int r;							\
1773 								\
1774 	va_start(args, fmt);					\
1775 								\
1776 	vaf.fmt = fmt;						\
1777 	vaf.va = &args;						\
1778 								\
1779 	r = __dev_printk(kern_level, dev, &vaf);		\
1780 	va_end(args);						\
1781 								\
1782 	return r;						\
1783 }								\
1784 EXPORT_SYMBOL(func);
1785 
1786 define_dev_printk_level(dev_emerg, KERN_EMERG);
1787 define_dev_printk_level(dev_alert, KERN_ALERT);
1788 define_dev_printk_level(dev_crit, KERN_CRIT);
1789 define_dev_printk_level(dev_err, KERN_ERR);
1790 define_dev_printk_level(dev_warn, KERN_WARNING);
1791 define_dev_printk_level(dev_notice, KERN_NOTICE);
1792 define_dev_printk_level(_dev_info, KERN_INFO);
1793 
1794 #endif
1795