xref: /openbmc/linux/drivers/base/core.c (revision 5d0e4d78)
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/fwnode.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/string.h>
20 #include <linux/kdev_t.h>
21 #include <linux/notifier.h>
22 #include <linux/of.h>
23 #include <linux/of_device.h>
24 #include <linux/genhd.h>
25 #include <linux/kallsyms.h>
26 #include <linux/mutex.h>
27 #include <linux/pm_runtime.h>
28 #include <linux/netdevice.h>
29 #include <linux/sched/signal.h>
30 #include <linux/sysfs.h>
31 
32 #include "base.h"
33 #include "power/power.h"
34 
35 #ifdef CONFIG_SYSFS_DEPRECATED
36 #ifdef CONFIG_SYSFS_DEPRECATED_V2
37 long sysfs_deprecated = 1;
38 #else
39 long sysfs_deprecated = 0;
40 #endif
41 static int __init sysfs_deprecated_setup(char *arg)
42 {
43 	return kstrtol(arg, 10, &sysfs_deprecated);
44 }
45 early_param("sysfs.deprecated", sysfs_deprecated_setup);
46 #endif
47 
48 /* Device links support. */
49 
50 #ifdef CONFIG_SRCU
51 static DEFINE_MUTEX(device_links_lock);
52 DEFINE_STATIC_SRCU(device_links_srcu);
53 
54 static inline void device_links_write_lock(void)
55 {
56 	mutex_lock(&device_links_lock);
57 }
58 
59 static inline void device_links_write_unlock(void)
60 {
61 	mutex_unlock(&device_links_lock);
62 }
63 
64 int device_links_read_lock(void)
65 {
66 	return srcu_read_lock(&device_links_srcu);
67 }
68 
69 void device_links_read_unlock(int idx)
70 {
71 	srcu_read_unlock(&device_links_srcu, idx);
72 }
73 #else /* !CONFIG_SRCU */
74 static DECLARE_RWSEM(device_links_lock);
75 
76 static inline void device_links_write_lock(void)
77 {
78 	down_write(&device_links_lock);
79 }
80 
81 static inline void device_links_write_unlock(void)
82 {
83 	up_write(&device_links_lock);
84 }
85 
86 int device_links_read_lock(void)
87 {
88 	down_read(&device_links_lock);
89 	return 0;
90 }
91 
92 void device_links_read_unlock(int not_used)
93 {
94 	up_read(&device_links_lock);
95 }
96 #endif /* !CONFIG_SRCU */
97 
98 /**
99  * device_is_dependent - Check if one device depends on another one
100  * @dev: Device to check dependencies for.
101  * @target: Device to check against.
102  *
103  * Check if @target depends on @dev or any device dependent on it (its child or
104  * its consumer etc).  Return 1 if that is the case or 0 otherwise.
105  */
106 static int device_is_dependent(struct device *dev, void *target)
107 {
108 	struct device_link *link;
109 	int ret;
110 
111 	if (WARN_ON(dev == target))
112 		return 1;
113 
114 	ret = device_for_each_child(dev, target, device_is_dependent);
115 	if (ret)
116 		return ret;
117 
118 	list_for_each_entry(link, &dev->links.consumers, s_node) {
119 		if (WARN_ON(link->consumer == target))
120 			return 1;
121 
122 		ret = device_is_dependent(link->consumer, target);
123 		if (ret)
124 			break;
125 	}
126 	return ret;
127 }
128 
129 static int device_reorder_to_tail(struct device *dev, void *not_used)
130 {
131 	struct device_link *link;
132 
133 	/*
134 	 * Devices that have not been registered yet will be put to the ends
135 	 * of the lists during the registration, so skip them here.
136 	 */
137 	if (device_is_registered(dev))
138 		devices_kset_move_last(dev);
139 
140 	if (device_pm_initialized(dev))
141 		device_pm_move_last(dev);
142 
143 	device_for_each_child(dev, NULL, device_reorder_to_tail);
144 	list_for_each_entry(link, &dev->links.consumers, s_node)
145 		device_reorder_to_tail(link->consumer, NULL);
146 
147 	return 0;
148 }
149 
150 /**
151  * device_link_add - Create a link between two devices.
152  * @consumer: Consumer end of the link.
153  * @supplier: Supplier end of the link.
154  * @flags: Link flags.
155  *
156  * The caller is responsible for the proper synchronization of the link creation
157  * with runtime PM.  First, setting the DL_FLAG_PM_RUNTIME flag will cause the
158  * runtime PM framework to take the link into account.  Second, if the
159  * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
160  * be forced into the active metastate and reference-counted upon the creation
161  * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
162  * ignored.
163  *
164  * If the DL_FLAG_AUTOREMOVE is set, the link will be removed automatically
165  * when the consumer device driver unbinds from it.  The combination of both
166  * DL_FLAG_AUTOREMOVE and DL_FLAG_STATELESS set is invalid and will cause NULL
167  * to be returned.
168  *
169  * A side effect of the link creation is re-ordering of dpm_list and the
170  * devices_kset list by moving the consumer device and all devices depending
171  * on it to the ends of these lists (that does not happen to devices that have
172  * not been registered when this function is called).
173  *
174  * The supplier device is required to be registered when this function is called
175  * and NULL will be returned if that is not the case.  The consumer device need
176  * not be registered, however.
177  */
178 struct device_link *device_link_add(struct device *consumer,
179 				    struct device *supplier, u32 flags)
180 {
181 	struct device_link *link;
182 
183 	if (!consumer || !supplier ||
184 	    ((flags & DL_FLAG_STATELESS) && (flags & DL_FLAG_AUTOREMOVE)))
185 		return NULL;
186 
187 	device_links_write_lock();
188 	device_pm_lock();
189 
190 	/*
191 	 * If the supplier has not been fully registered yet or there is a
192 	 * reverse dependency between the consumer and the supplier already in
193 	 * the graph, return NULL.
194 	 */
195 	if (!device_pm_initialized(supplier)
196 	    || device_is_dependent(consumer, supplier)) {
197 		link = NULL;
198 		goto out;
199 	}
200 
201 	list_for_each_entry(link, &supplier->links.consumers, s_node)
202 		if (link->consumer == consumer)
203 			goto out;
204 
205 	link = kzalloc(sizeof(*link), GFP_KERNEL);
206 	if (!link)
207 		goto out;
208 
209 	if (flags & DL_FLAG_PM_RUNTIME) {
210 		if (flags & DL_FLAG_RPM_ACTIVE) {
211 			if (pm_runtime_get_sync(supplier) < 0) {
212 				pm_runtime_put_noidle(supplier);
213 				kfree(link);
214 				link = NULL;
215 				goto out;
216 			}
217 			link->rpm_active = true;
218 		}
219 		pm_runtime_new_link(consumer);
220 	}
221 	get_device(supplier);
222 	link->supplier = supplier;
223 	INIT_LIST_HEAD(&link->s_node);
224 	get_device(consumer);
225 	link->consumer = consumer;
226 	INIT_LIST_HEAD(&link->c_node);
227 	link->flags = flags;
228 
229 	/* Determine the initial link state. */
230 	if (flags & DL_FLAG_STATELESS) {
231 		link->status = DL_STATE_NONE;
232 	} else {
233 		switch (supplier->links.status) {
234 		case DL_DEV_DRIVER_BOUND:
235 			switch (consumer->links.status) {
236 			case DL_DEV_PROBING:
237 				/*
238 				 * Balance the decrementation of the supplier's
239 				 * runtime PM usage counter after consumer probe
240 				 * in driver_probe_device().
241 				 */
242 				if (flags & DL_FLAG_PM_RUNTIME)
243 					pm_runtime_get_sync(supplier);
244 
245 				link->status = DL_STATE_CONSUMER_PROBE;
246 				break;
247 			case DL_DEV_DRIVER_BOUND:
248 				link->status = DL_STATE_ACTIVE;
249 				break;
250 			default:
251 				link->status = DL_STATE_AVAILABLE;
252 				break;
253 			}
254 			break;
255 		case DL_DEV_UNBINDING:
256 			link->status = DL_STATE_SUPPLIER_UNBIND;
257 			break;
258 		default:
259 			link->status = DL_STATE_DORMANT;
260 			break;
261 		}
262 	}
263 
264 	/*
265 	 * Move the consumer and all of the devices depending on it to the end
266 	 * of dpm_list and the devices_kset list.
267 	 *
268 	 * It is necessary to hold dpm_list locked throughout all that or else
269 	 * we may end up suspending with a wrong ordering of it.
270 	 */
271 	device_reorder_to_tail(consumer, NULL);
272 
273 	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
274 	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
275 
276 	dev_info(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
277 
278  out:
279 	device_pm_unlock();
280 	device_links_write_unlock();
281 	return link;
282 }
283 EXPORT_SYMBOL_GPL(device_link_add);
284 
285 static void device_link_free(struct device_link *link)
286 {
287 	put_device(link->consumer);
288 	put_device(link->supplier);
289 	kfree(link);
290 }
291 
292 #ifdef CONFIG_SRCU
293 static void __device_link_free_srcu(struct rcu_head *rhead)
294 {
295 	device_link_free(container_of(rhead, struct device_link, rcu_head));
296 }
297 
298 static void __device_link_del(struct device_link *link)
299 {
300 	dev_info(link->consumer, "Dropping the link to %s\n",
301 		 dev_name(link->supplier));
302 
303 	if (link->flags & DL_FLAG_PM_RUNTIME)
304 		pm_runtime_drop_link(link->consumer);
305 
306 	list_del_rcu(&link->s_node);
307 	list_del_rcu(&link->c_node);
308 	call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);
309 }
310 #else /* !CONFIG_SRCU */
311 static void __device_link_del(struct device_link *link)
312 {
313 	dev_info(link->consumer, "Dropping the link to %s\n",
314 		 dev_name(link->supplier));
315 
316 	list_del(&link->s_node);
317 	list_del(&link->c_node);
318 	device_link_free(link);
319 }
320 #endif /* !CONFIG_SRCU */
321 
322 /**
323  * device_link_del - Delete a link between two devices.
324  * @link: Device link to delete.
325  *
326  * The caller must ensure proper synchronization of this function with runtime
327  * PM.
328  */
329 void device_link_del(struct device_link *link)
330 {
331 	device_links_write_lock();
332 	device_pm_lock();
333 	__device_link_del(link);
334 	device_pm_unlock();
335 	device_links_write_unlock();
336 }
337 EXPORT_SYMBOL_GPL(device_link_del);
338 
339 static void device_links_missing_supplier(struct device *dev)
340 {
341 	struct device_link *link;
342 
343 	list_for_each_entry(link, &dev->links.suppliers, c_node)
344 		if (link->status == DL_STATE_CONSUMER_PROBE)
345 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
346 }
347 
348 /**
349  * device_links_check_suppliers - Check presence of supplier drivers.
350  * @dev: Consumer device.
351  *
352  * Check links from this device to any suppliers.  Walk the list of the device's
353  * links to suppliers and see if all of them are available.  If not, simply
354  * return -EPROBE_DEFER.
355  *
356  * We need to guarantee that the supplier will not go away after the check has
357  * been positive here.  It only can go away in __device_release_driver() and
358  * that function  checks the device's links to consumers.  This means we need to
359  * mark the link as "consumer probe in progress" to make the supplier removal
360  * wait for us to complete (or bad things may happen).
361  *
362  * Links with the DL_FLAG_STATELESS flag set are ignored.
363  */
364 int device_links_check_suppliers(struct device *dev)
365 {
366 	struct device_link *link;
367 	int ret = 0;
368 
369 	device_links_write_lock();
370 
371 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
372 		if (link->flags & DL_FLAG_STATELESS)
373 			continue;
374 
375 		if (link->status != DL_STATE_AVAILABLE) {
376 			device_links_missing_supplier(dev);
377 			ret = -EPROBE_DEFER;
378 			break;
379 		}
380 		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
381 	}
382 	dev->links.status = DL_DEV_PROBING;
383 
384 	device_links_write_unlock();
385 	return ret;
386 }
387 
388 /**
389  * device_links_driver_bound - Update device links after probing its driver.
390  * @dev: Device to update the links for.
391  *
392  * The probe has been successful, so update links from this device to any
393  * consumers by changing their status to "available".
394  *
395  * Also change the status of @dev's links to suppliers to "active".
396  *
397  * Links with the DL_FLAG_STATELESS flag set are ignored.
398  */
399 void device_links_driver_bound(struct device *dev)
400 {
401 	struct device_link *link;
402 
403 	device_links_write_lock();
404 
405 	list_for_each_entry(link, &dev->links.consumers, s_node) {
406 		if (link->flags & DL_FLAG_STATELESS)
407 			continue;
408 
409 		WARN_ON(link->status != DL_STATE_DORMANT);
410 		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
411 	}
412 
413 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
414 		if (link->flags & DL_FLAG_STATELESS)
415 			continue;
416 
417 		WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
418 		WRITE_ONCE(link->status, DL_STATE_ACTIVE);
419 	}
420 
421 	dev->links.status = DL_DEV_DRIVER_BOUND;
422 
423 	device_links_write_unlock();
424 }
425 
426 /**
427  * __device_links_no_driver - Update links of a device without a driver.
428  * @dev: Device without a drvier.
429  *
430  * Delete all non-persistent links from this device to any suppliers.
431  *
432  * Persistent links stay around, but their status is changed to "available",
433  * unless they already are in the "supplier unbind in progress" state in which
434  * case they need not be updated.
435  *
436  * Links with the DL_FLAG_STATELESS flag set are ignored.
437  */
438 static void __device_links_no_driver(struct device *dev)
439 {
440 	struct device_link *link, *ln;
441 
442 	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
443 		if (link->flags & DL_FLAG_STATELESS)
444 			continue;
445 
446 		if (link->flags & DL_FLAG_AUTOREMOVE)
447 			__device_link_del(link);
448 		else if (link->status != DL_STATE_SUPPLIER_UNBIND)
449 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
450 	}
451 
452 	dev->links.status = DL_DEV_NO_DRIVER;
453 }
454 
455 void device_links_no_driver(struct device *dev)
456 {
457 	device_links_write_lock();
458 	__device_links_no_driver(dev);
459 	device_links_write_unlock();
460 }
461 
462 /**
463  * device_links_driver_cleanup - Update links after driver removal.
464  * @dev: Device whose driver has just gone away.
465  *
466  * Update links to consumers for @dev by changing their status to "dormant" and
467  * invoke %__device_links_no_driver() to update links to suppliers for it as
468  * appropriate.
469  *
470  * Links with the DL_FLAG_STATELESS flag set are ignored.
471  */
472 void device_links_driver_cleanup(struct device *dev)
473 {
474 	struct device_link *link;
475 
476 	device_links_write_lock();
477 
478 	list_for_each_entry(link, &dev->links.consumers, s_node) {
479 		if (link->flags & DL_FLAG_STATELESS)
480 			continue;
481 
482 		WARN_ON(link->flags & DL_FLAG_AUTOREMOVE);
483 		WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
484 		WRITE_ONCE(link->status, DL_STATE_DORMANT);
485 	}
486 
487 	__device_links_no_driver(dev);
488 
489 	device_links_write_unlock();
490 }
491 
492 /**
493  * device_links_busy - Check if there are any busy links to consumers.
494  * @dev: Device to check.
495  *
496  * Check each consumer of the device and return 'true' if its link's status
497  * is one of "consumer probe" or "active" (meaning that the given consumer is
498  * probing right now or its driver is present).  Otherwise, change the link
499  * state to "supplier unbind" to prevent the consumer from being probed
500  * successfully going forward.
501  *
502  * Return 'false' if there are no probing or active consumers.
503  *
504  * Links with the DL_FLAG_STATELESS flag set are ignored.
505  */
506 bool device_links_busy(struct device *dev)
507 {
508 	struct device_link *link;
509 	bool ret = false;
510 
511 	device_links_write_lock();
512 
513 	list_for_each_entry(link, &dev->links.consumers, s_node) {
514 		if (link->flags & DL_FLAG_STATELESS)
515 			continue;
516 
517 		if (link->status == DL_STATE_CONSUMER_PROBE
518 		    || link->status == DL_STATE_ACTIVE) {
519 			ret = true;
520 			break;
521 		}
522 		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
523 	}
524 
525 	dev->links.status = DL_DEV_UNBINDING;
526 
527 	device_links_write_unlock();
528 	return ret;
529 }
530 
531 /**
532  * device_links_unbind_consumers - Force unbind consumers of the given device.
533  * @dev: Device to unbind the consumers of.
534  *
535  * Walk the list of links to consumers for @dev and if any of them is in the
536  * "consumer probe" state, wait for all device probes in progress to complete
537  * and start over.
538  *
539  * If that's not the case, change the status of the link to "supplier unbind"
540  * and check if the link was in the "active" state.  If so, force the consumer
541  * driver to unbind and start over (the consumer will not re-probe as we have
542  * changed the state of the link already).
543  *
544  * Links with the DL_FLAG_STATELESS flag set are ignored.
545  */
546 void device_links_unbind_consumers(struct device *dev)
547 {
548 	struct device_link *link;
549 
550  start:
551 	device_links_write_lock();
552 
553 	list_for_each_entry(link, &dev->links.consumers, s_node) {
554 		enum device_link_state status;
555 
556 		if (link->flags & DL_FLAG_STATELESS)
557 			continue;
558 
559 		status = link->status;
560 		if (status == DL_STATE_CONSUMER_PROBE) {
561 			device_links_write_unlock();
562 
563 			wait_for_device_probe();
564 			goto start;
565 		}
566 		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
567 		if (status == DL_STATE_ACTIVE) {
568 			struct device *consumer = link->consumer;
569 
570 			get_device(consumer);
571 
572 			device_links_write_unlock();
573 
574 			device_release_driver_internal(consumer, NULL,
575 						       consumer->parent);
576 			put_device(consumer);
577 			goto start;
578 		}
579 	}
580 
581 	device_links_write_unlock();
582 }
583 
584 /**
585  * device_links_purge - Delete existing links to other devices.
586  * @dev: Target device.
587  */
588 static void device_links_purge(struct device *dev)
589 {
590 	struct device_link *link, *ln;
591 
592 	/*
593 	 * Delete all of the remaining links from this device to any other
594 	 * devices (either consumers or suppliers).
595 	 */
596 	device_links_write_lock();
597 
598 	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
599 		WARN_ON(link->status == DL_STATE_ACTIVE);
600 		__device_link_del(link);
601 	}
602 
603 	list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
604 		WARN_ON(link->status != DL_STATE_DORMANT &&
605 			link->status != DL_STATE_NONE);
606 		__device_link_del(link);
607 	}
608 
609 	device_links_write_unlock();
610 }
611 
612 /* Device links support end. */
613 
614 int (*platform_notify)(struct device *dev) = NULL;
615 int (*platform_notify_remove)(struct device *dev) = NULL;
616 static struct kobject *dev_kobj;
617 struct kobject *sysfs_dev_char_kobj;
618 struct kobject *sysfs_dev_block_kobj;
619 
620 static DEFINE_MUTEX(device_hotplug_lock);
621 
622 void lock_device_hotplug(void)
623 {
624 	mutex_lock(&device_hotplug_lock);
625 }
626 
627 void unlock_device_hotplug(void)
628 {
629 	mutex_unlock(&device_hotplug_lock);
630 }
631 
632 int lock_device_hotplug_sysfs(void)
633 {
634 	if (mutex_trylock(&device_hotplug_lock))
635 		return 0;
636 
637 	/* Avoid busy looping (5 ms of sleep should do). */
638 	msleep(5);
639 	return restart_syscall();
640 }
641 
642 #ifdef CONFIG_BLOCK
643 static inline int device_is_not_partition(struct device *dev)
644 {
645 	return !(dev->type == &part_type);
646 }
647 #else
648 static inline int device_is_not_partition(struct device *dev)
649 {
650 	return 1;
651 }
652 #endif
653 
654 /**
655  * dev_driver_string - Return a device's driver name, if at all possible
656  * @dev: struct device to get the name of
657  *
658  * Will return the device's driver's name if it is bound to a device.  If
659  * the device is not bound to a driver, it will return the name of the bus
660  * it is attached to.  If it is not attached to a bus either, an empty
661  * string will be returned.
662  */
663 const char *dev_driver_string(const struct device *dev)
664 {
665 	struct device_driver *drv;
666 
667 	/* dev->driver can change to NULL underneath us because of unbinding,
668 	 * so be careful about accessing it.  dev->bus and dev->class should
669 	 * never change once they are set, so they don't need special care.
670 	 */
671 	drv = ACCESS_ONCE(dev->driver);
672 	return drv ? drv->name :
673 			(dev->bus ? dev->bus->name :
674 			(dev->class ? dev->class->name : ""));
675 }
676 EXPORT_SYMBOL(dev_driver_string);
677 
678 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
679 
680 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
681 			     char *buf)
682 {
683 	struct device_attribute *dev_attr = to_dev_attr(attr);
684 	struct device *dev = kobj_to_dev(kobj);
685 	ssize_t ret = -EIO;
686 
687 	if (dev_attr->show)
688 		ret = dev_attr->show(dev, dev_attr, buf);
689 	if (ret >= (ssize_t)PAGE_SIZE) {
690 		print_symbol("dev_attr_show: %s returned bad count\n",
691 				(unsigned long)dev_attr->show);
692 	}
693 	return ret;
694 }
695 
696 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
697 			      const char *buf, size_t count)
698 {
699 	struct device_attribute *dev_attr = to_dev_attr(attr);
700 	struct device *dev = kobj_to_dev(kobj);
701 	ssize_t ret = -EIO;
702 
703 	if (dev_attr->store)
704 		ret = dev_attr->store(dev, dev_attr, buf, count);
705 	return ret;
706 }
707 
708 static const struct sysfs_ops dev_sysfs_ops = {
709 	.show	= dev_attr_show,
710 	.store	= dev_attr_store,
711 };
712 
713 #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
714 
715 ssize_t device_store_ulong(struct device *dev,
716 			   struct device_attribute *attr,
717 			   const char *buf, size_t size)
718 {
719 	struct dev_ext_attribute *ea = to_ext_attr(attr);
720 	char *end;
721 	unsigned long new = simple_strtoul(buf, &end, 0);
722 	if (end == buf)
723 		return -EINVAL;
724 	*(unsigned long *)(ea->var) = new;
725 	/* Always return full write size even if we didn't consume all */
726 	return size;
727 }
728 EXPORT_SYMBOL_GPL(device_store_ulong);
729 
730 ssize_t device_show_ulong(struct device *dev,
731 			  struct device_attribute *attr,
732 			  char *buf)
733 {
734 	struct dev_ext_attribute *ea = to_ext_attr(attr);
735 	return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
736 }
737 EXPORT_SYMBOL_GPL(device_show_ulong);
738 
739 ssize_t device_store_int(struct device *dev,
740 			 struct device_attribute *attr,
741 			 const char *buf, size_t size)
742 {
743 	struct dev_ext_attribute *ea = to_ext_attr(attr);
744 	char *end;
745 	long new = simple_strtol(buf, &end, 0);
746 	if (end == buf || new > INT_MAX || new < INT_MIN)
747 		return -EINVAL;
748 	*(int *)(ea->var) = new;
749 	/* Always return full write size even if we didn't consume all */
750 	return size;
751 }
752 EXPORT_SYMBOL_GPL(device_store_int);
753 
754 ssize_t device_show_int(struct device *dev,
755 			struct device_attribute *attr,
756 			char *buf)
757 {
758 	struct dev_ext_attribute *ea = to_ext_attr(attr);
759 
760 	return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
761 }
762 EXPORT_SYMBOL_GPL(device_show_int);
763 
764 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
765 			  const char *buf, size_t size)
766 {
767 	struct dev_ext_attribute *ea = to_ext_attr(attr);
768 
769 	if (strtobool(buf, ea->var) < 0)
770 		return -EINVAL;
771 
772 	return size;
773 }
774 EXPORT_SYMBOL_GPL(device_store_bool);
775 
776 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
777 			 char *buf)
778 {
779 	struct dev_ext_attribute *ea = to_ext_attr(attr);
780 
781 	return snprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var));
782 }
783 EXPORT_SYMBOL_GPL(device_show_bool);
784 
785 /**
786  * device_release - free device structure.
787  * @kobj: device's kobject.
788  *
789  * This is called once the reference count for the object
790  * reaches 0. We forward the call to the device's release
791  * method, which should handle actually freeing the structure.
792  */
793 static void device_release(struct kobject *kobj)
794 {
795 	struct device *dev = kobj_to_dev(kobj);
796 	struct device_private *p = dev->p;
797 
798 	/*
799 	 * Some platform devices are driven without driver attached
800 	 * and managed resources may have been acquired.  Make sure
801 	 * all resources are released.
802 	 *
803 	 * Drivers still can add resources into device after device
804 	 * is deleted but alive, so release devres here to avoid
805 	 * possible memory leak.
806 	 */
807 	devres_release_all(dev);
808 
809 	if (dev->release)
810 		dev->release(dev);
811 	else if (dev->type && dev->type->release)
812 		dev->type->release(dev);
813 	else if (dev->class && dev->class->dev_release)
814 		dev->class->dev_release(dev);
815 	else
816 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
817 			"function, it is broken and must be fixed.\n",
818 			dev_name(dev));
819 	kfree(p);
820 }
821 
822 static const void *device_namespace(struct kobject *kobj)
823 {
824 	struct device *dev = kobj_to_dev(kobj);
825 	const void *ns = NULL;
826 
827 	if (dev->class && dev->class->ns_type)
828 		ns = dev->class->namespace(dev);
829 
830 	return ns;
831 }
832 
833 static struct kobj_type device_ktype = {
834 	.release	= device_release,
835 	.sysfs_ops	= &dev_sysfs_ops,
836 	.namespace	= device_namespace,
837 };
838 
839 
840 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
841 {
842 	struct kobj_type *ktype = get_ktype(kobj);
843 
844 	if (ktype == &device_ktype) {
845 		struct device *dev = kobj_to_dev(kobj);
846 		if (dev->bus)
847 			return 1;
848 		if (dev->class)
849 			return 1;
850 	}
851 	return 0;
852 }
853 
854 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
855 {
856 	struct device *dev = kobj_to_dev(kobj);
857 
858 	if (dev->bus)
859 		return dev->bus->name;
860 	if (dev->class)
861 		return dev->class->name;
862 	return NULL;
863 }
864 
865 static int dev_uevent(struct kset *kset, struct kobject *kobj,
866 		      struct kobj_uevent_env *env)
867 {
868 	struct device *dev = kobj_to_dev(kobj);
869 	int retval = 0;
870 
871 	/* add device node properties if present */
872 	if (MAJOR(dev->devt)) {
873 		const char *tmp;
874 		const char *name;
875 		umode_t mode = 0;
876 		kuid_t uid = GLOBAL_ROOT_UID;
877 		kgid_t gid = GLOBAL_ROOT_GID;
878 
879 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
880 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
881 		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
882 		if (name) {
883 			add_uevent_var(env, "DEVNAME=%s", name);
884 			if (mode)
885 				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
886 			if (!uid_eq(uid, GLOBAL_ROOT_UID))
887 				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
888 			if (!gid_eq(gid, GLOBAL_ROOT_GID))
889 				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
890 			kfree(tmp);
891 		}
892 	}
893 
894 	if (dev->type && dev->type->name)
895 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
896 
897 	if (dev->driver)
898 		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
899 
900 	/* Add common DT information about the device */
901 	of_device_uevent(dev, env);
902 
903 	/* have the bus specific function add its stuff */
904 	if (dev->bus && dev->bus->uevent) {
905 		retval = dev->bus->uevent(dev, env);
906 		if (retval)
907 			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
908 				 dev_name(dev), __func__, retval);
909 	}
910 
911 	/* have the class specific function add its stuff */
912 	if (dev->class && dev->class->dev_uevent) {
913 		retval = dev->class->dev_uevent(dev, env);
914 		if (retval)
915 			pr_debug("device: '%s': %s: class uevent() "
916 				 "returned %d\n", dev_name(dev),
917 				 __func__, retval);
918 	}
919 
920 	/* have the device type specific function add its stuff */
921 	if (dev->type && dev->type->uevent) {
922 		retval = dev->type->uevent(dev, env);
923 		if (retval)
924 			pr_debug("device: '%s': %s: dev_type uevent() "
925 				 "returned %d\n", dev_name(dev),
926 				 __func__, retval);
927 	}
928 
929 	return retval;
930 }
931 
932 static const struct kset_uevent_ops device_uevent_ops = {
933 	.filter =	dev_uevent_filter,
934 	.name =		dev_uevent_name,
935 	.uevent =	dev_uevent,
936 };
937 
938 static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
939 			   char *buf)
940 {
941 	struct kobject *top_kobj;
942 	struct kset *kset;
943 	struct kobj_uevent_env *env = NULL;
944 	int i;
945 	size_t count = 0;
946 	int retval;
947 
948 	/* search the kset, the device belongs to */
949 	top_kobj = &dev->kobj;
950 	while (!top_kobj->kset && top_kobj->parent)
951 		top_kobj = top_kobj->parent;
952 	if (!top_kobj->kset)
953 		goto out;
954 
955 	kset = top_kobj->kset;
956 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
957 		goto out;
958 
959 	/* respect filter */
960 	if (kset->uevent_ops && kset->uevent_ops->filter)
961 		if (!kset->uevent_ops->filter(kset, &dev->kobj))
962 			goto out;
963 
964 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
965 	if (!env)
966 		return -ENOMEM;
967 
968 	/* let the kset specific function add its keys */
969 	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
970 	if (retval)
971 		goto out;
972 
973 	/* copy keys to file */
974 	for (i = 0; i < env->envp_idx; i++)
975 		count += sprintf(&buf[count], "%s\n", env->envp[i]);
976 out:
977 	kfree(env);
978 	return count;
979 }
980 
981 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
982 			    const char *buf, size_t count)
983 {
984 	if (kobject_synth_uevent(&dev->kobj, buf, count))
985 		dev_err(dev, "uevent: failed to send synthetic uevent\n");
986 
987 	return count;
988 }
989 static DEVICE_ATTR_RW(uevent);
990 
991 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
992 			   char *buf)
993 {
994 	bool val;
995 
996 	device_lock(dev);
997 	val = !dev->offline;
998 	device_unlock(dev);
999 	return sprintf(buf, "%u\n", val);
1000 }
1001 
1002 static ssize_t online_store(struct device *dev, struct device_attribute *attr,
1003 			    const char *buf, size_t count)
1004 {
1005 	bool val;
1006 	int ret;
1007 
1008 	ret = strtobool(buf, &val);
1009 	if (ret < 0)
1010 		return ret;
1011 
1012 	ret = lock_device_hotplug_sysfs();
1013 	if (ret)
1014 		return ret;
1015 
1016 	ret = val ? device_online(dev) : device_offline(dev);
1017 	unlock_device_hotplug();
1018 	return ret < 0 ? ret : count;
1019 }
1020 static DEVICE_ATTR_RW(online);
1021 
1022 int device_add_groups(struct device *dev, const struct attribute_group **groups)
1023 {
1024 	return sysfs_create_groups(&dev->kobj, groups);
1025 }
1026 
1027 void device_remove_groups(struct device *dev,
1028 			  const struct attribute_group **groups)
1029 {
1030 	sysfs_remove_groups(&dev->kobj, groups);
1031 }
1032 
1033 static int device_add_attrs(struct device *dev)
1034 {
1035 	struct class *class = dev->class;
1036 	const struct device_type *type = dev->type;
1037 	int error;
1038 
1039 	if (class) {
1040 		error = device_add_groups(dev, class->dev_groups);
1041 		if (error)
1042 			return error;
1043 	}
1044 
1045 	if (type) {
1046 		error = device_add_groups(dev, type->groups);
1047 		if (error)
1048 			goto err_remove_class_groups;
1049 	}
1050 
1051 	error = device_add_groups(dev, dev->groups);
1052 	if (error)
1053 		goto err_remove_type_groups;
1054 
1055 	if (device_supports_offline(dev) && !dev->offline_disabled) {
1056 		error = device_create_file(dev, &dev_attr_online);
1057 		if (error)
1058 			goto err_remove_dev_groups;
1059 	}
1060 
1061 	return 0;
1062 
1063  err_remove_dev_groups:
1064 	device_remove_groups(dev, dev->groups);
1065  err_remove_type_groups:
1066 	if (type)
1067 		device_remove_groups(dev, type->groups);
1068  err_remove_class_groups:
1069 	if (class)
1070 		device_remove_groups(dev, class->dev_groups);
1071 
1072 	return error;
1073 }
1074 
1075 static void device_remove_attrs(struct device *dev)
1076 {
1077 	struct class *class = dev->class;
1078 	const struct device_type *type = dev->type;
1079 
1080 	device_remove_file(dev, &dev_attr_online);
1081 	device_remove_groups(dev, dev->groups);
1082 
1083 	if (type)
1084 		device_remove_groups(dev, type->groups);
1085 
1086 	if (class)
1087 		device_remove_groups(dev, class->dev_groups);
1088 }
1089 
1090 static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
1091 			char *buf)
1092 {
1093 	return print_dev_t(buf, dev->devt);
1094 }
1095 static DEVICE_ATTR_RO(dev);
1096 
1097 /* /sys/devices/ */
1098 struct kset *devices_kset;
1099 
1100 /**
1101  * devices_kset_move_before - Move device in the devices_kset's list.
1102  * @deva: Device to move.
1103  * @devb: Device @deva should come before.
1104  */
1105 static void devices_kset_move_before(struct device *deva, struct device *devb)
1106 {
1107 	if (!devices_kset)
1108 		return;
1109 	pr_debug("devices_kset: Moving %s before %s\n",
1110 		 dev_name(deva), dev_name(devb));
1111 	spin_lock(&devices_kset->list_lock);
1112 	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
1113 	spin_unlock(&devices_kset->list_lock);
1114 }
1115 
1116 /**
1117  * devices_kset_move_after - Move device in the devices_kset's list.
1118  * @deva: Device to move
1119  * @devb: Device @deva should come after.
1120  */
1121 static void devices_kset_move_after(struct device *deva, struct device *devb)
1122 {
1123 	if (!devices_kset)
1124 		return;
1125 	pr_debug("devices_kset: Moving %s after %s\n",
1126 		 dev_name(deva), dev_name(devb));
1127 	spin_lock(&devices_kset->list_lock);
1128 	list_move(&deva->kobj.entry, &devb->kobj.entry);
1129 	spin_unlock(&devices_kset->list_lock);
1130 }
1131 
1132 /**
1133  * devices_kset_move_last - move the device to the end of devices_kset's list.
1134  * @dev: device to move
1135  */
1136 void devices_kset_move_last(struct device *dev)
1137 {
1138 	if (!devices_kset)
1139 		return;
1140 	pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
1141 	spin_lock(&devices_kset->list_lock);
1142 	list_move_tail(&dev->kobj.entry, &devices_kset->list);
1143 	spin_unlock(&devices_kset->list_lock);
1144 }
1145 
1146 /**
1147  * device_create_file - create sysfs attribute file for device.
1148  * @dev: device.
1149  * @attr: device attribute descriptor.
1150  */
1151 int device_create_file(struct device *dev,
1152 		       const struct device_attribute *attr)
1153 {
1154 	int error = 0;
1155 
1156 	if (dev) {
1157 		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
1158 			"Attribute %s: write permission without 'store'\n",
1159 			attr->attr.name);
1160 		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
1161 			"Attribute %s: read permission without 'show'\n",
1162 			attr->attr.name);
1163 		error = sysfs_create_file(&dev->kobj, &attr->attr);
1164 	}
1165 
1166 	return error;
1167 }
1168 EXPORT_SYMBOL_GPL(device_create_file);
1169 
1170 /**
1171  * device_remove_file - remove sysfs attribute file.
1172  * @dev: device.
1173  * @attr: device attribute descriptor.
1174  */
1175 void device_remove_file(struct device *dev,
1176 			const struct device_attribute *attr)
1177 {
1178 	if (dev)
1179 		sysfs_remove_file(&dev->kobj, &attr->attr);
1180 }
1181 EXPORT_SYMBOL_GPL(device_remove_file);
1182 
1183 /**
1184  * device_remove_file_self - remove sysfs attribute file from its own method.
1185  * @dev: device.
1186  * @attr: device attribute descriptor.
1187  *
1188  * See kernfs_remove_self() for details.
1189  */
1190 bool device_remove_file_self(struct device *dev,
1191 			     const struct device_attribute *attr)
1192 {
1193 	if (dev)
1194 		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
1195 	else
1196 		return false;
1197 }
1198 EXPORT_SYMBOL_GPL(device_remove_file_self);
1199 
1200 /**
1201  * device_create_bin_file - create sysfs binary attribute file for device.
1202  * @dev: device.
1203  * @attr: device binary attribute descriptor.
1204  */
1205 int device_create_bin_file(struct device *dev,
1206 			   const struct bin_attribute *attr)
1207 {
1208 	int error = -EINVAL;
1209 	if (dev)
1210 		error = sysfs_create_bin_file(&dev->kobj, attr);
1211 	return error;
1212 }
1213 EXPORT_SYMBOL_GPL(device_create_bin_file);
1214 
1215 /**
1216  * device_remove_bin_file - remove sysfs binary attribute file
1217  * @dev: device.
1218  * @attr: device binary attribute descriptor.
1219  */
1220 void device_remove_bin_file(struct device *dev,
1221 			    const struct bin_attribute *attr)
1222 {
1223 	if (dev)
1224 		sysfs_remove_bin_file(&dev->kobj, attr);
1225 }
1226 EXPORT_SYMBOL_GPL(device_remove_bin_file);
1227 
1228 static void klist_children_get(struct klist_node *n)
1229 {
1230 	struct device_private *p = to_device_private_parent(n);
1231 	struct device *dev = p->device;
1232 
1233 	get_device(dev);
1234 }
1235 
1236 static void klist_children_put(struct klist_node *n)
1237 {
1238 	struct device_private *p = to_device_private_parent(n);
1239 	struct device *dev = p->device;
1240 
1241 	put_device(dev);
1242 }
1243 
1244 /**
1245  * device_initialize - init device structure.
1246  * @dev: device.
1247  *
1248  * This prepares the device for use by other layers by initializing
1249  * its fields.
1250  * It is the first half of device_register(), if called by
1251  * that function, though it can also be called separately, so one
1252  * may use @dev's fields. In particular, get_device()/put_device()
1253  * may be used for reference counting of @dev after calling this
1254  * function.
1255  *
1256  * All fields in @dev must be initialized by the caller to 0, except
1257  * for those explicitly set to some other value.  The simplest
1258  * approach is to use kzalloc() to allocate the structure containing
1259  * @dev.
1260  *
1261  * NOTE: Use put_device() to give up your reference instead of freeing
1262  * @dev directly once you have called this function.
1263  */
1264 void device_initialize(struct device *dev)
1265 {
1266 	dev->kobj.kset = devices_kset;
1267 	kobject_init(&dev->kobj, &device_ktype);
1268 	INIT_LIST_HEAD(&dev->dma_pools);
1269 	mutex_init(&dev->mutex);
1270 	lockdep_set_novalidate_class(&dev->mutex);
1271 	spin_lock_init(&dev->devres_lock);
1272 	INIT_LIST_HEAD(&dev->devres_head);
1273 	device_pm_init(dev);
1274 	set_dev_node(dev, -1);
1275 #ifdef CONFIG_GENERIC_MSI_IRQ
1276 	INIT_LIST_HEAD(&dev->msi_list);
1277 #endif
1278 	INIT_LIST_HEAD(&dev->links.consumers);
1279 	INIT_LIST_HEAD(&dev->links.suppliers);
1280 	dev->links.status = DL_DEV_NO_DRIVER;
1281 }
1282 EXPORT_SYMBOL_GPL(device_initialize);
1283 
1284 struct kobject *virtual_device_parent(struct device *dev)
1285 {
1286 	static struct kobject *virtual_dir = NULL;
1287 
1288 	if (!virtual_dir)
1289 		virtual_dir = kobject_create_and_add("virtual",
1290 						     &devices_kset->kobj);
1291 
1292 	return virtual_dir;
1293 }
1294 
1295 struct class_dir {
1296 	struct kobject kobj;
1297 	struct class *class;
1298 };
1299 
1300 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
1301 
1302 static void class_dir_release(struct kobject *kobj)
1303 {
1304 	struct class_dir *dir = to_class_dir(kobj);
1305 	kfree(dir);
1306 }
1307 
1308 static const
1309 struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
1310 {
1311 	struct class_dir *dir = to_class_dir(kobj);
1312 	return dir->class->ns_type;
1313 }
1314 
1315 static struct kobj_type class_dir_ktype = {
1316 	.release	= class_dir_release,
1317 	.sysfs_ops	= &kobj_sysfs_ops,
1318 	.child_ns_type	= class_dir_child_ns_type
1319 };
1320 
1321 static struct kobject *
1322 class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
1323 {
1324 	struct class_dir *dir;
1325 	int retval;
1326 
1327 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
1328 	if (!dir)
1329 		return NULL;
1330 
1331 	dir->class = class;
1332 	kobject_init(&dir->kobj, &class_dir_ktype);
1333 
1334 	dir->kobj.kset = &class->p->glue_dirs;
1335 
1336 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
1337 	if (retval < 0) {
1338 		kobject_put(&dir->kobj);
1339 		return NULL;
1340 	}
1341 	return &dir->kobj;
1342 }
1343 
1344 static DEFINE_MUTEX(gdp_mutex);
1345 
1346 static struct kobject *get_device_parent(struct device *dev,
1347 					 struct device *parent)
1348 {
1349 	if (dev->class) {
1350 		struct kobject *kobj = NULL;
1351 		struct kobject *parent_kobj;
1352 		struct kobject *k;
1353 
1354 #ifdef CONFIG_BLOCK
1355 		/* block disks show up in /sys/block */
1356 		if (sysfs_deprecated && dev->class == &block_class) {
1357 			if (parent && parent->class == &block_class)
1358 				return &parent->kobj;
1359 			return &block_class.p->subsys.kobj;
1360 		}
1361 #endif
1362 
1363 		/*
1364 		 * If we have no parent, we live in "virtual".
1365 		 * Class-devices with a non class-device as parent, live
1366 		 * in a "glue" directory to prevent namespace collisions.
1367 		 */
1368 		if (parent == NULL)
1369 			parent_kobj = virtual_device_parent(dev);
1370 		else if (parent->class && !dev->class->ns_type)
1371 			return &parent->kobj;
1372 		else
1373 			parent_kobj = &parent->kobj;
1374 
1375 		mutex_lock(&gdp_mutex);
1376 
1377 		/* find our class-directory at the parent and reference it */
1378 		spin_lock(&dev->class->p->glue_dirs.list_lock);
1379 		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
1380 			if (k->parent == parent_kobj) {
1381 				kobj = kobject_get(k);
1382 				break;
1383 			}
1384 		spin_unlock(&dev->class->p->glue_dirs.list_lock);
1385 		if (kobj) {
1386 			mutex_unlock(&gdp_mutex);
1387 			return kobj;
1388 		}
1389 
1390 		/* or create a new class-directory at the parent device */
1391 		k = class_dir_create_and_add(dev->class, parent_kobj);
1392 		/* do not emit an uevent for this simple "glue" directory */
1393 		mutex_unlock(&gdp_mutex);
1394 		return k;
1395 	}
1396 
1397 	/* subsystems can specify a default root directory for their devices */
1398 	if (!parent && dev->bus && dev->bus->dev_root)
1399 		return &dev->bus->dev_root->kobj;
1400 
1401 	if (parent)
1402 		return &parent->kobj;
1403 	return NULL;
1404 }
1405 
1406 static inline bool live_in_glue_dir(struct kobject *kobj,
1407 				    struct device *dev)
1408 {
1409 	if (!kobj || !dev->class ||
1410 	    kobj->kset != &dev->class->p->glue_dirs)
1411 		return false;
1412 	return true;
1413 }
1414 
1415 static inline struct kobject *get_glue_dir(struct device *dev)
1416 {
1417 	return dev->kobj.parent;
1418 }
1419 
1420 /*
1421  * make sure cleaning up dir as the last step, we need to make
1422  * sure .release handler of kobject is run with holding the
1423  * global lock
1424  */
1425 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
1426 {
1427 	/* see if we live in a "glue" directory */
1428 	if (!live_in_glue_dir(glue_dir, dev))
1429 		return;
1430 
1431 	mutex_lock(&gdp_mutex);
1432 	kobject_put(glue_dir);
1433 	mutex_unlock(&gdp_mutex);
1434 }
1435 
1436 static int device_add_class_symlinks(struct device *dev)
1437 {
1438 	struct device_node *of_node = dev_of_node(dev);
1439 	int error;
1440 
1441 	if (of_node) {
1442 		error = sysfs_create_link(&dev->kobj, &of_node->kobj,"of_node");
1443 		if (error)
1444 			dev_warn(dev, "Error %d creating of_node link\n",error);
1445 		/* An error here doesn't warrant bringing down the device */
1446 	}
1447 
1448 	if (!dev->class)
1449 		return 0;
1450 
1451 	error = sysfs_create_link(&dev->kobj,
1452 				  &dev->class->p->subsys.kobj,
1453 				  "subsystem");
1454 	if (error)
1455 		goto out_devnode;
1456 
1457 	if (dev->parent && device_is_not_partition(dev)) {
1458 		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
1459 					  "device");
1460 		if (error)
1461 			goto out_subsys;
1462 	}
1463 
1464 #ifdef CONFIG_BLOCK
1465 	/* /sys/block has directories and does not need symlinks */
1466 	if (sysfs_deprecated && dev->class == &block_class)
1467 		return 0;
1468 #endif
1469 
1470 	/* link in the class directory pointing to the device */
1471 	error = sysfs_create_link(&dev->class->p->subsys.kobj,
1472 				  &dev->kobj, dev_name(dev));
1473 	if (error)
1474 		goto out_device;
1475 
1476 	return 0;
1477 
1478 out_device:
1479 	sysfs_remove_link(&dev->kobj, "device");
1480 
1481 out_subsys:
1482 	sysfs_remove_link(&dev->kobj, "subsystem");
1483 out_devnode:
1484 	sysfs_remove_link(&dev->kobj, "of_node");
1485 	return error;
1486 }
1487 
1488 static void device_remove_class_symlinks(struct device *dev)
1489 {
1490 	if (dev_of_node(dev))
1491 		sysfs_remove_link(&dev->kobj, "of_node");
1492 
1493 	if (!dev->class)
1494 		return;
1495 
1496 	if (dev->parent && device_is_not_partition(dev))
1497 		sysfs_remove_link(&dev->kobj, "device");
1498 	sysfs_remove_link(&dev->kobj, "subsystem");
1499 #ifdef CONFIG_BLOCK
1500 	if (sysfs_deprecated && dev->class == &block_class)
1501 		return;
1502 #endif
1503 	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
1504 }
1505 
1506 /**
1507  * dev_set_name - set a device name
1508  * @dev: device
1509  * @fmt: format string for the device's name
1510  */
1511 int dev_set_name(struct device *dev, const char *fmt, ...)
1512 {
1513 	va_list vargs;
1514 	int err;
1515 
1516 	va_start(vargs, fmt);
1517 	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
1518 	va_end(vargs);
1519 	return err;
1520 }
1521 EXPORT_SYMBOL_GPL(dev_set_name);
1522 
1523 /**
1524  * device_to_dev_kobj - select a /sys/dev/ directory for the device
1525  * @dev: device
1526  *
1527  * By default we select char/ for new entries.  Setting class->dev_obj
1528  * to NULL prevents an entry from being created.  class->dev_kobj must
1529  * be set (or cleared) before any devices are registered to the class
1530  * otherwise device_create_sys_dev_entry() and
1531  * device_remove_sys_dev_entry() will disagree about the presence of
1532  * the link.
1533  */
1534 static struct kobject *device_to_dev_kobj(struct device *dev)
1535 {
1536 	struct kobject *kobj;
1537 
1538 	if (dev->class)
1539 		kobj = dev->class->dev_kobj;
1540 	else
1541 		kobj = sysfs_dev_char_kobj;
1542 
1543 	return kobj;
1544 }
1545 
1546 static int device_create_sys_dev_entry(struct device *dev)
1547 {
1548 	struct kobject *kobj = device_to_dev_kobj(dev);
1549 	int error = 0;
1550 	char devt_str[15];
1551 
1552 	if (kobj) {
1553 		format_dev_t(devt_str, dev->devt);
1554 		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
1555 	}
1556 
1557 	return error;
1558 }
1559 
1560 static void device_remove_sys_dev_entry(struct device *dev)
1561 {
1562 	struct kobject *kobj = device_to_dev_kobj(dev);
1563 	char devt_str[15];
1564 
1565 	if (kobj) {
1566 		format_dev_t(devt_str, dev->devt);
1567 		sysfs_remove_link(kobj, devt_str);
1568 	}
1569 }
1570 
1571 int device_private_init(struct device *dev)
1572 {
1573 	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
1574 	if (!dev->p)
1575 		return -ENOMEM;
1576 	dev->p->device = dev;
1577 	klist_init(&dev->p->klist_children, klist_children_get,
1578 		   klist_children_put);
1579 	INIT_LIST_HEAD(&dev->p->deferred_probe);
1580 	return 0;
1581 }
1582 
1583 /**
1584  * device_add - add device to device hierarchy.
1585  * @dev: device.
1586  *
1587  * This is part 2 of device_register(), though may be called
1588  * separately _iff_ device_initialize() has been called separately.
1589  *
1590  * This adds @dev to the kobject hierarchy via kobject_add(), adds it
1591  * to the global and sibling lists for the device, then
1592  * adds it to the other relevant subsystems of the driver model.
1593  *
1594  * Do not call this routine or device_register() more than once for
1595  * any device structure.  The driver model core is not designed to work
1596  * with devices that get unregistered and then spring back to life.
1597  * (Among other things, it's very hard to guarantee that all references
1598  * to the previous incarnation of @dev have been dropped.)  Allocate
1599  * and register a fresh new struct device instead.
1600  *
1601  * NOTE: _Never_ directly free @dev after calling this function, even
1602  * if it returned an error! Always use put_device() to give up your
1603  * reference instead.
1604  */
1605 int device_add(struct device *dev)
1606 {
1607 	struct device *parent;
1608 	struct kobject *kobj;
1609 	struct class_interface *class_intf;
1610 	int error = -EINVAL;
1611 	struct kobject *glue_dir = NULL;
1612 
1613 	dev = get_device(dev);
1614 	if (!dev)
1615 		goto done;
1616 
1617 	if (!dev->p) {
1618 		error = device_private_init(dev);
1619 		if (error)
1620 			goto done;
1621 	}
1622 
1623 	/*
1624 	 * for statically allocated devices, which should all be converted
1625 	 * some day, we need to initialize the name. We prevent reading back
1626 	 * the name, and force the use of dev_name()
1627 	 */
1628 	if (dev->init_name) {
1629 		dev_set_name(dev, "%s", dev->init_name);
1630 		dev->init_name = NULL;
1631 	}
1632 
1633 	/* subsystems can specify simple device enumeration */
1634 	if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
1635 		dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
1636 
1637 	if (!dev_name(dev)) {
1638 		error = -EINVAL;
1639 		goto name_error;
1640 	}
1641 
1642 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1643 
1644 	parent = get_device(dev->parent);
1645 	kobj = get_device_parent(dev, parent);
1646 	if (kobj)
1647 		dev->kobj.parent = kobj;
1648 
1649 	/* use parent numa_node */
1650 	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
1651 		set_dev_node(dev, dev_to_node(parent));
1652 
1653 	/* first, register with generic layer. */
1654 	/* we require the name to be set before, and pass NULL */
1655 	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
1656 	if (error) {
1657 		glue_dir = get_glue_dir(dev);
1658 		goto Error;
1659 	}
1660 
1661 	/* notify platform of device entry */
1662 	if (platform_notify)
1663 		platform_notify(dev);
1664 
1665 	error = device_create_file(dev, &dev_attr_uevent);
1666 	if (error)
1667 		goto attrError;
1668 
1669 	error = device_add_class_symlinks(dev);
1670 	if (error)
1671 		goto SymlinkError;
1672 	error = device_add_attrs(dev);
1673 	if (error)
1674 		goto AttrsError;
1675 	error = bus_add_device(dev);
1676 	if (error)
1677 		goto BusError;
1678 	error = dpm_sysfs_add(dev);
1679 	if (error)
1680 		goto DPMError;
1681 	device_pm_add(dev);
1682 
1683 	if (MAJOR(dev->devt)) {
1684 		error = device_create_file(dev, &dev_attr_dev);
1685 		if (error)
1686 			goto DevAttrError;
1687 
1688 		error = device_create_sys_dev_entry(dev);
1689 		if (error)
1690 			goto SysEntryError;
1691 
1692 		devtmpfs_create_node(dev);
1693 	}
1694 
1695 	/* Notify clients of device addition.  This call must come
1696 	 * after dpm_sysfs_add() and before kobject_uevent().
1697 	 */
1698 	if (dev->bus)
1699 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1700 					     BUS_NOTIFY_ADD_DEVICE, dev);
1701 
1702 	kobject_uevent(&dev->kobj, KOBJ_ADD);
1703 	bus_probe_device(dev);
1704 	if (parent)
1705 		klist_add_tail(&dev->p->knode_parent,
1706 			       &parent->p->klist_children);
1707 
1708 	if (dev->class) {
1709 		mutex_lock(&dev->class->p->mutex);
1710 		/* tie the class to the device */
1711 		klist_add_tail(&dev->knode_class,
1712 			       &dev->class->p->klist_devices);
1713 
1714 		/* notify any interfaces that the device is here */
1715 		list_for_each_entry(class_intf,
1716 				    &dev->class->p->interfaces, node)
1717 			if (class_intf->add_dev)
1718 				class_intf->add_dev(dev, class_intf);
1719 		mutex_unlock(&dev->class->p->mutex);
1720 	}
1721 done:
1722 	put_device(dev);
1723 	return error;
1724  SysEntryError:
1725 	if (MAJOR(dev->devt))
1726 		device_remove_file(dev, &dev_attr_dev);
1727  DevAttrError:
1728 	device_pm_remove(dev);
1729 	dpm_sysfs_remove(dev);
1730  DPMError:
1731 	bus_remove_device(dev);
1732  BusError:
1733 	device_remove_attrs(dev);
1734  AttrsError:
1735 	device_remove_class_symlinks(dev);
1736  SymlinkError:
1737 	device_remove_file(dev, &dev_attr_uevent);
1738  attrError:
1739 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1740 	glue_dir = get_glue_dir(dev);
1741 	kobject_del(&dev->kobj);
1742  Error:
1743 	cleanup_glue_dir(dev, glue_dir);
1744 	put_device(parent);
1745 name_error:
1746 	kfree(dev->p);
1747 	dev->p = NULL;
1748 	goto done;
1749 }
1750 EXPORT_SYMBOL_GPL(device_add);
1751 
1752 /**
1753  * device_register - register a device with the system.
1754  * @dev: pointer to the device structure
1755  *
1756  * This happens in two clean steps - initialize the device
1757  * and add it to the system. The two steps can be called
1758  * separately, but this is the easiest and most common.
1759  * I.e. you should only call the two helpers separately if
1760  * have a clearly defined need to use and refcount the device
1761  * before it is added to the hierarchy.
1762  *
1763  * For more information, see the kerneldoc for device_initialize()
1764  * and device_add().
1765  *
1766  * NOTE: _Never_ directly free @dev after calling this function, even
1767  * if it returned an error! Always use put_device() to give up the
1768  * reference initialized in this function instead.
1769  */
1770 int device_register(struct device *dev)
1771 {
1772 	device_initialize(dev);
1773 	return device_add(dev);
1774 }
1775 EXPORT_SYMBOL_GPL(device_register);
1776 
1777 /**
1778  * get_device - increment reference count for device.
1779  * @dev: device.
1780  *
1781  * This simply forwards the call to kobject_get(), though
1782  * we do take care to provide for the case that we get a NULL
1783  * pointer passed in.
1784  */
1785 struct device *get_device(struct device *dev)
1786 {
1787 	return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
1788 }
1789 EXPORT_SYMBOL_GPL(get_device);
1790 
1791 /**
1792  * put_device - decrement reference count.
1793  * @dev: device in question.
1794  */
1795 void put_device(struct device *dev)
1796 {
1797 	/* might_sleep(); */
1798 	if (dev)
1799 		kobject_put(&dev->kobj);
1800 }
1801 EXPORT_SYMBOL_GPL(put_device);
1802 
1803 /**
1804  * device_del - delete device from system.
1805  * @dev: device.
1806  *
1807  * This is the first part of the device unregistration
1808  * sequence. This removes the device from the lists we control
1809  * from here, has it removed from the other driver model
1810  * subsystems it was added to in device_add(), and removes it
1811  * from the kobject hierarchy.
1812  *
1813  * NOTE: this should be called manually _iff_ device_add() was
1814  * also called manually.
1815  */
1816 void device_del(struct device *dev)
1817 {
1818 	struct device *parent = dev->parent;
1819 	struct kobject *glue_dir = NULL;
1820 	struct class_interface *class_intf;
1821 
1822 	/* Notify clients of device removal.  This call must come
1823 	 * before dpm_sysfs_remove().
1824 	 */
1825 	if (dev->bus)
1826 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1827 					     BUS_NOTIFY_DEL_DEVICE, dev);
1828 
1829 	device_links_purge(dev);
1830 	dpm_sysfs_remove(dev);
1831 	if (parent)
1832 		klist_del(&dev->p->knode_parent);
1833 	if (MAJOR(dev->devt)) {
1834 		devtmpfs_delete_node(dev);
1835 		device_remove_sys_dev_entry(dev);
1836 		device_remove_file(dev, &dev_attr_dev);
1837 	}
1838 	if (dev->class) {
1839 		device_remove_class_symlinks(dev);
1840 
1841 		mutex_lock(&dev->class->p->mutex);
1842 		/* notify any interfaces that the device is now gone */
1843 		list_for_each_entry(class_intf,
1844 				    &dev->class->p->interfaces, node)
1845 			if (class_intf->remove_dev)
1846 				class_intf->remove_dev(dev, class_intf);
1847 		/* remove the device from the class list */
1848 		klist_del(&dev->knode_class);
1849 		mutex_unlock(&dev->class->p->mutex);
1850 	}
1851 	device_remove_file(dev, &dev_attr_uevent);
1852 	device_remove_attrs(dev);
1853 	bus_remove_device(dev);
1854 	device_pm_remove(dev);
1855 	driver_deferred_probe_del(dev);
1856 	device_remove_properties(dev);
1857 
1858 	/* Notify the platform of the removal, in case they
1859 	 * need to do anything...
1860 	 */
1861 	if (platform_notify_remove)
1862 		platform_notify_remove(dev);
1863 	if (dev->bus)
1864 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1865 					     BUS_NOTIFY_REMOVED_DEVICE, dev);
1866 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1867 	glue_dir = get_glue_dir(dev);
1868 	kobject_del(&dev->kobj);
1869 	cleanup_glue_dir(dev, glue_dir);
1870 	put_device(parent);
1871 }
1872 EXPORT_SYMBOL_GPL(device_del);
1873 
1874 /**
1875  * device_unregister - unregister device from system.
1876  * @dev: device going away.
1877  *
1878  * We do this in two parts, like we do device_register(). First,
1879  * we remove it from all the subsystems with device_del(), then
1880  * we decrement the reference count via put_device(). If that
1881  * is the final reference count, the device will be cleaned up
1882  * via device_release() above. Otherwise, the structure will
1883  * stick around until the final reference to the device is dropped.
1884  */
1885 void device_unregister(struct device *dev)
1886 {
1887 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1888 	device_del(dev);
1889 	put_device(dev);
1890 }
1891 EXPORT_SYMBOL_GPL(device_unregister);
1892 
1893 static struct device *prev_device(struct klist_iter *i)
1894 {
1895 	struct klist_node *n = klist_prev(i);
1896 	struct device *dev = NULL;
1897 	struct device_private *p;
1898 
1899 	if (n) {
1900 		p = to_device_private_parent(n);
1901 		dev = p->device;
1902 	}
1903 	return dev;
1904 }
1905 
1906 static struct device *next_device(struct klist_iter *i)
1907 {
1908 	struct klist_node *n = klist_next(i);
1909 	struct device *dev = NULL;
1910 	struct device_private *p;
1911 
1912 	if (n) {
1913 		p = to_device_private_parent(n);
1914 		dev = p->device;
1915 	}
1916 	return dev;
1917 }
1918 
1919 /**
1920  * device_get_devnode - path of device node file
1921  * @dev: device
1922  * @mode: returned file access mode
1923  * @uid: returned file owner
1924  * @gid: returned file group
1925  * @tmp: possibly allocated string
1926  *
1927  * Return the relative path of a possible device node.
1928  * Non-default names may need to allocate a memory to compose
1929  * a name. This memory is returned in tmp and needs to be
1930  * freed by the caller.
1931  */
1932 const char *device_get_devnode(struct device *dev,
1933 			       umode_t *mode, kuid_t *uid, kgid_t *gid,
1934 			       const char **tmp)
1935 {
1936 	char *s;
1937 
1938 	*tmp = NULL;
1939 
1940 	/* the device type may provide a specific name */
1941 	if (dev->type && dev->type->devnode)
1942 		*tmp = dev->type->devnode(dev, mode, uid, gid);
1943 	if (*tmp)
1944 		return *tmp;
1945 
1946 	/* the class may provide a specific name */
1947 	if (dev->class && dev->class->devnode)
1948 		*tmp = dev->class->devnode(dev, mode);
1949 	if (*tmp)
1950 		return *tmp;
1951 
1952 	/* return name without allocation, tmp == NULL */
1953 	if (strchr(dev_name(dev), '!') == NULL)
1954 		return dev_name(dev);
1955 
1956 	/* replace '!' in the name with '/' */
1957 	s = kstrdup(dev_name(dev), GFP_KERNEL);
1958 	if (!s)
1959 		return NULL;
1960 	strreplace(s, '!', '/');
1961 	return *tmp = s;
1962 }
1963 
1964 /**
1965  * device_for_each_child - device child iterator.
1966  * @parent: parent struct device.
1967  * @fn: function to be called for each device.
1968  * @data: data for the callback.
1969  *
1970  * Iterate over @parent's child devices, and call @fn for each,
1971  * passing it @data.
1972  *
1973  * We check the return of @fn each time. If it returns anything
1974  * other than 0, we break out and return that value.
1975  */
1976 int device_for_each_child(struct device *parent, void *data,
1977 			  int (*fn)(struct device *dev, void *data))
1978 {
1979 	struct klist_iter i;
1980 	struct device *child;
1981 	int error = 0;
1982 
1983 	if (!parent->p)
1984 		return 0;
1985 
1986 	klist_iter_init(&parent->p->klist_children, &i);
1987 	while ((child = next_device(&i)) && !error)
1988 		error = fn(child, data);
1989 	klist_iter_exit(&i);
1990 	return error;
1991 }
1992 EXPORT_SYMBOL_GPL(device_for_each_child);
1993 
1994 /**
1995  * device_for_each_child_reverse - device child iterator in reversed order.
1996  * @parent: parent struct device.
1997  * @fn: function to be called for each device.
1998  * @data: data for the callback.
1999  *
2000  * Iterate over @parent's child devices, and call @fn for each,
2001  * passing it @data.
2002  *
2003  * We check the return of @fn each time. If it returns anything
2004  * other than 0, we break out and return that value.
2005  */
2006 int device_for_each_child_reverse(struct device *parent, void *data,
2007 				  int (*fn)(struct device *dev, void *data))
2008 {
2009 	struct klist_iter i;
2010 	struct device *child;
2011 	int error = 0;
2012 
2013 	if (!parent->p)
2014 		return 0;
2015 
2016 	klist_iter_init(&parent->p->klist_children, &i);
2017 	while ((child = prev_device(&i)) && !error)
2018 		error = fn(child, data);
2019 	klist_iter_exit(&i);
2020 	return error;
2021 }
2022 EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
2023 
2024 /**
2025  * device_find_child - device iterator for locating a particular device.
2026  * @parent: parent struct device
2027  * @match: Callback function to check device
2028  * @data: Data to pass to match function
2029  *
2030  * This is similar to the device_for_each_child() function above, but it
2031  * returns a reference to a device that is 'found' for later use, as
2032  * determined by the @match callback.
2033  *
2034  * The callback should return 0 if the device doesn't match and non-zero
2035  * if it does.  If the callback returns non-zero and a reference to the
2036  * current device can be obtained, this function will return to the caller
2037  * and not iterate over any more devices.
2038  *
2039  * NOTE: you will need to drop the reference with put_device() after use.
2040  */
2041 struct device *device_find_child(struct device *parent, void *data,
2042 				 int (*match)(struct device *dev, void *data))
2043 {
2044 	struct klist_iter i;
2045 	struct device *child;
2046 
2047 	if (!parent)
2048 		return NULL;
2049 
2050 	klist_iter_init(&parent->p->klist_children, &i);
2051 	while ((child = next_device(&i)))
2052 		if (match(child, data) && get_device(child))
2053 			break;
2054 	klist_iter_exit(&i);
2055 	return child;
2056 }
2057 EXPORT_SYMBOL_GPL(device_find_child);
2058 
2059 int __init devices_init(void)
2060 {
2061 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
2062 	if (!devices_kset)
2063 		return -ENOMEM;
2064 	dev_kobj = kobject_create_and_add("dev", NULL);
2065 	if (!dev_kobj)
2066 		goto dev_kobj_err;
2067 	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
2068 	if (!sysfs_dev_block_kobj)
2069 		goto block_kobj_err;
2070 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
2071 	if (!sysfs_dev_char_kobj)
2072 		goto char_kobj_err;
2073 
2074 	return 0;
2075 
2076  char_kobj_err:
2077 	kobject_put(sysfs_dev_block_kobj);
2078  block_kobj_err:
2079 	kobject_put(dev_kobj);
2080  dev_kobj_err:
2081 	kset_unregister(devices_kset);
2082 	return -ENOMEM;
2083 }
2084 
2085 static int device_check_offline(struct device *dev, void *not_used)
2086 {
2087 	int ret;
2088 
2089 	ret = device_for_each_child(dev, NULL, device_check_offline);
2090 	if (ret)
2091 		return ret;
2092 
2093 	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
2094 }
2095 
2096 /**
2097  * device_offline - Prepare the device for hot-removal.
2098  * @dev: Device to be put offline.
2099  *
2100  * Execute the device bus type's .offline() callback, if present, to prepare
2101  * the device for a subsequent hot-removal.  If that succeeds, the device must
2102  * not be used until either it is removed or its bus type's .online() callback
2103  * is executed.
2104  *
2105  * Call under device_hotplug_lock.
2106  */
2107 int device_offline(struct device *dev)
2108 {
2109 	int ret;
2110 
2111 	if (dev->offline_disabled)
2112 		return -EPERM;
2113 
2114 	ret = device_for_each_child(dev, NULL, device_check_offline);
2115 	if (ret)
2116 		return ret;
2117 
2118 	device_lock(dev);
2119 	if (device_supports_offline(dev)) {
2120 		if (dev->offline) {
2121 			ret = 1;
2122 		} else {
2123 			ret = dev->bus->offline(dev);
2124 			if (!ret) {
2125 				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
2126 				dev->offline = true;
2127 			}
2128 		}
2129 	}
2130 	device_unlock(dev);
2131 
2132 	return ret;
2133 }
2134 
2135 /**
2136  * device_online - Put the device back online after successful device_offline().
2137  * @dev: Device to be put back online.
2138  *
2139  * If device_offline() has been successfully executed for @dev, but the device
2140  * has not been removed subsequently, execute its bus type's .online() callback
2141  * to indicate that the device can be used again.
2142  *
2143  * Call under device_hotplug_lock.
2144  */
2145 int device_online(struct device *dev)
2146 {
2147 	int ret = 0;
2148 
2149 	device_lock(dev);
2150 	if (device_supports_offline(dev)) {
2151 		if (dev->offline) {
2152 			ret = dev->bus->online(dev);
2153 			if (!ret) {
2154 				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
2155 				dev->offline = false;
2156 			}
2157 		} else {
2158 			ret = 1;
2159 		}
2160 	}
2161 	device_unlock(dev);
2162 
2163 	return ret;
2164 }
2165 
2166 struct root_device {
2167 	struct device dev;
2168 	struct module *owner;
2169 };
2170 
2171 static inline struct root_device *to_root_device(struct device *d)
2172 {
2173 	return container_of(d, struct root_device, dev);
2174 }
2175 
2176 static void root_device_release(struct device *dev)
2177 {
2178 	kfree(to_root_device(dev));
2179 }
2180 
2181 /**
2182  * __root_device_register - allocate and register a root device
2183  * @name: root device name
2184  * @owner: owner module of the root device, usually THIS_MODULE
2185  *
2186  * This function allocates a root device and registers it
2187  * using device_register(). In order to free the returned
2188  * device, use root_device_unregister().
2189  *
2190  * Root devices are dummy devices which allow other devices
2191  * to be grouped under /sys/devices. Use this function to
2192  * allocate a root device and then use it as the parent of
2193  * any device which should appear under /sys/devices/{name}
2194  *
2195  * The /sys/devices/{name} directory will also contain a
2196  * 'module' symlink which points to the @owner directory
2197  * in sysfs.
2198  *
2199  * Returns &struct device pointer on success, or ERR_PTR() on error.
2200  *
2201  * Note: You probably want to use root_device_register().
2202  */
2203 struct device *__root_device_register(const char *name, struct module *owner)
2204 {
2205 	struct root_device *root;
2206 	int err = -ENOMEM;
2207 
2208 	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
2209 	if (!root)
2210 		return ERR_PTR(err);
2211 
2212 	err = dev_set_name(&root->dev, "%s", name);
2213 	if (err) {
2214 		kfree(root);
2215 		return ERR_PTR(err);
2216 	}
2217 
2218 	root->dev.release = root_device_release;
2219 
2220 	err = device_register(&root->dev);
2221 	if (err) {
2222 		put_device(&root->dev);
2223 		return ERR_PTR(err);
2224 	}
2225 
2226 #ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
2227 	if (owner) {
2228 		struct module_kobject *mk = &owner->mkobj;
2229 
2230 		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
2231 		if (err) {
2232 			device_unregister(&root->dev);
2233 			return ERR_PTR(err);
2234 		}
2235 		root->owner = owner;
2236 	}
2237 #endif
2238 
2239 	return &root->dev;
2240 }
2241 EXPORT_SYMBOL_GPL(__root_device_register);
2242 
2243 /**
2244  * root_device_unregister - unregister and free a root device
2245  * @dev: device going away
2246  *
2247  * This function unregisters and cleans up a device that was created by
2248  * root_device_register().
2249  */
2250 void root_device_unregister(struct device *dev)
2251 {
2252 	struct root_device *root = to_root_device(dev);
2253 
2254 	if (root->owner)
2255 		sysfs_remove_link(&root->dev.kobj, "module");
2256 
2257 	device_unregister(dev);
2258 }
2259 EXPORT_SYMBOL_GPL(root_device_unregister);
2260 
2261 
2262 static void device_create_release(struct device *dev)
2263 {
2264 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
2265 	kfree(dev);
2266 }
2267 
2268 static struct device *
2269 device_create_groups_vargs(struct class *class, struct device *parent,
2270 			   dev_t devt, void *drvdata,
2271 			   const struct attribute_group **groups,
2272 			   const char *fmt, va_list args)
2273 {
2274 	struct device *dev = NULL;
2275 	int retval = -ENODEV;
2276 
2277 	if (class == NULL || IS_ERR(class))
2278 		goto error;
2279 
2280 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
2281 	if (!dev) {
2282 		retval = -ENOMEM;
2283 		goto error;
2284 	}
2285 
2286 	device_initialize(dev);
2287 	dev->devt = devt;
2288 	dev->class = class;
2289 	dev->parent = parent;
2290 	dev->groups = groups;
2291 	dev->release = device_create_release;
2292 	dev_set_drvdata(dev, drvdata);
2293 
2294 	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
2295 	if (retval)
2296 		goto error;
2297 
2298 	retval = device_add(dev);
2299 	if (retval)
2300 		goto error;
2301 
2302 	return dev;
2303 
2304 error:
2305 	put_device(dev);
2306 	return ERR_PTR(retval);
2307 }
2308 
2309 /**
2310  * device_create_vargs - creates a device and registers it with sysfs
2311  * @class: pointer to the struct class that this device should be registered to
2312  * @parent: pointer to the parent struct device of this new device, if any
2313  * @devt: the dev_t for the char device to be added
2314  * @drvdata: the data to be added to the device for callbacks
2315  * @fmt: string for the device's name
2316  * @args: va_list for the device's name
2317  *
2318  * This function can be used by char device classes.  A struct device
2319  * will be created in sysfs, registered to the specified class.
2320  *
2321  * A "dev" file will be created, showing the dev_t for the device, if
2322  * the dev_t is not 0,0.
2323  * If a pointer to a parent struct device is passed in, the newly created
2324  * struct device will be a child of that device in sysfs.
2325  * The pointer to the struct device will be returned from the call.
2326  * Any further sysfs files that might be required can be created using this
2327  * pointer.
2328  *
2329  * Returns &struct device pointer on success, or ERR_PTR() on error.
2330  *
2331  * Note: the struct class passed to this function must have previously
2332  * been created with a call to class_create().
2333  */
2334 struct device *device_create_vargs(struct class *class, struct device *parent,
2335 				   dev_t devt, void *drvdata, const char *fmt,
2336 				   va_list args)
2337 {
2338 	return device_create_groups_vargs(class, parent, devt, drvdata, NULL,
2339 					  fmt, args);
2340 }
2341 EXPORT_SYMBOL_GPL(device_create_vargs);
2342 
2343 /**
2344  * device_create - creates a device and registers it with sysfs
2345  * @class: pointer to the struct class that this device should be registered to
2346  * @parent: pointer to the parent struct device of this new device, if any
2347  * @devt: the dev_t for the char device to be added
2348  * @drvdata: the data to be added to the device for callbacks
2349  * @fmt: string for the device's name
2350  *
2351  * This function can be used by char device classes.  A struct device
2352  * will be created in sysfs, registered to the specified class.
2353  *
2354  * A "dev" file will be created, showing the dev_t for the device, if
2355  * the dev_t is not 0,0.
2356  * If a pointer to a parent struct device is passed in, the newly created
2357  * struct device will be a child of that device in sysfs.
2358  * The pointer to the struct device will be returned from the call.
2359  * Any further sysfs files that might be required can be created using this
2360  * pointer.
2361  *
2362  * Returns &struct device pointer on success, or ERR_PTR() on error.
2363  *
2364  * Note: the struct class passed to this function must have previously
2365  * been created with a call to class_create().
2366  */
2367 struct device *device_create(struct class *class, struct device *parent,
2368 			     dev_t devt, void *drvdata, const char *fmt, ...)
2369 {
2370 	va_list vargs;
2371 	struct device *dev;
2372 
2373 	va_start(vargs, fmt);
2374 	dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);
2375 	va_end(vargs);
2376 	return dev;
2377 }
2378 EXPORT_SYMBOL_GPL(device_create);
2379 
2380 /**
2381  * device_create_with_groups - creates a device and registers it with sysfs
2382  * @class: pointer to the struct class that this device should be registered to
2383  * @parent: pointer to the parent struct device of this new device, if any
2384  * @devt: the dev_t for the char device to be added
2385  * @drvdata: the data to be added to the device for callbacks
2386  * @groups: NULL-terminated list of attribute groups to be created
2387  * @fmt: string for the device's name
2388  *
2389  * This function can be used by char device classes.  A struct device
2390  * will be created in sysfs, registered to the specified class.
2391  * Additional attributes specified in the groups parameter will also
2392  * be created automatically.
2393  *
2394  * A "dev" file will be created, showing the dev_t for the device, if
2395  * the dev_t is not 0,0.
2396  * If a pointer to a parent struct device is passed in, the newly created
2397  * struct device will be a child of that device in sysfs.
2398  * The pointer to the struct device will be returned from the call.
2399  * Any further sysfs files that might be required can be created using this
2400  * pointer.
2401  *
2402  * Returns &struct device pointer on success, or ERR_PTR() on error.
2403  *
2404  * Note: the struct class passed to this function must have previously
2405  * been created with a call to class_create().
2406  */
2407 struct device *device_create_with_groups(struct class *class,
2408 					 struct device *parent, dev_t devt,
2409 					 void *drvdata,
2410 					 const struct attribute_group **groups,
2411 					 const char *fmt, ...)
2412 {
2413 	va_list vargs;
2414 	struct device *dev;
2415 
2416 	va_start(vargs, fmt);
2417 	dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
2418 					 fmt, vargs);
2419 	va_end(vargs);
2420 	return dev;
2421 }
2422 EXPORT_SYMBOL_GPL(device_create_with_groups);
2423 
2424 static int __match_devt(struct device *dev, const void *data)
2425 {
2426 	const dev_t *devt = data;
2427 
2428 	return dev->devt == *devt;
2429 }
2430 
2431 /**
2432  * device_destroy - removes a device that was created with device_create()
2433  * @class: pointer to the struct class that this device was registered with
2434  * @devt: the dev_t of the device that was previously registered
2435  *
2436  * This call unregisters and cleans up a device that was created with a
2437  * call to device_create().
2438  */
2439 void device_destroy(struct class *class, dev_t devt)
2440 {
2441 	struct device *dev;
2442 
2443 	dev = class_find_device(class, NULL, &devt, __match_devt);
2444 	if (dev) {
2445 		put_device(dev);
2446 		device_unregister(dev);
2447 	}
2448 }
2449 EXPORT_SYMBOL_GPL(device_destroy);
2450 
2451 /**
2452  * device_rename - renames a device
2453  * @dev: the pointer to the struct device to be renamed
2454  * @new_name: the new name of the device
2455  *
2456  * It is the responsibility of the caller to provide mutual
2457  * exclusion between two different calls of device_rename
2458  * on the same device to ensure that new_name is valid and
2459  * won't conflict with other devices.
2460  *
2461  * Note: Don't call this function.  Currently, the networking layer calls this
2462  * function, but that will change.  The following text from Kay Sievers offers
2463  * some insight:
2464  *
2465  * Renaming devices is racy at many levels, symlinks and other stuff are not
2466  * replaced atomically, and you get a "move" uevent, but it's not easy to
2467  * connect the event to the old and new device. Device nodes are not renamed at
2468  * all, there isn't even support for that in the kernel now.
2469  *
2470  * In the meantime, during renaming, your target name might be taken by another
2471  * driver, creating conflicts. Or the old name is taken directly after you
2472  * renamed it -- then you get events for the same DEVPATH, before you even see
2473  * the "move" event. It's just a mess, and nothing new should ever rely on
2474  * kernel device renaming. Besides that, it's not even implemented now for
2475  * other things than (driver-core wise very simple) network devices.
2476  *
2477  * We are currently about to change network renaming in udev to completely
2478  * disallow renaming of devices in the same namespace as the kernel uses,
2479  * because we can't solve the problems properly, that arise with swapping names
2480  * of multiple interfaces without races. Means, renaming of eth[0-9]* will only
2481  * be allowed to some other name than eth[0-9]*, for the aforementioned
2482  * reasons.
2483  *
2484  * Make up a "real" name in the driver before you register anything, or add
2485  * some other attributes for userspace to find the device, or use udev to add
2486  * symlinks -- but never rename kernel devices later, it's a complete mess. We
2487  * don't even want to get into that and try to implement the missing pieces in
2488  * the core. We really have other pieces to fix in the driver core mess. :)
2489  */
2490 int device_rename(struct device *dev, const char *new_name)
2491 {
2492 	struct kobject *kobj = &dev->kobj;
2493 	char *old_device_name = NULL;
2494 	int error;
2495 
2496 	dev = get_device(dev);
2497 	if (!dev)
2498 		return -EINVAL;
2499 
2500 	dev_dbg(dev, "renaming to %s\n", new_name);
2501 
2502 	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
2503 	if (!old_device_name) {
2504 		error = -ENOMEM;
2505 		goto out;
2506 	}
2507 
2508 	if (dev->class) {
2509 		error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
2510 					     kobj, old_device_name,
2511 					     new_name, kobject_namespace(kobj));
2512 		if (error)
2513 			goto out;
2514 	}
2515 
2516 	error = kobject_rename(kobj, new_name);
2517 	if (error)
2518 		goto out;
2519 
2520 out:
2521 	put_device(dev);
2522 
2523 	kfree(old_device_name);
2524 
2525 	return error;
2526 }
2527 EXPORT_SYMBOL_GPL(device_rename);
2528 
2529 static int device_move_class_links(struct device *dev,
2530 				   struct device *old_parent,
2531 				   struct device *new_parent)
2532 {
2533 	int error = 0;
2534 
2535 	if (old_parent)
2536 		sysfs_remove_link(&dev->kobj, "device");
2537 	if (new_parent)
2538 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
2539 					  "device");
2540 	return error;
2541 }
2542 
2543 /**
2544  * device_move - moves a device to a new parent
2545  * @dev: the pointer to the struct device to be moved
2546  * @new_parent: the new parent of the device (can by NULL)
2547  * @dpm_order: how to reorder the dpm_list
2548  */
2549 int device_move(struct device *dev, struct device *new_parent,
2550 		enum dpm_order dpm_order)
2551 {
2552 	int error;
2553 	struct device *old_parent;
2554 	struct kobject *new_parent_kobj;
2555 
2556 	dev = get_device(dev);
2557 	if (!dev)
2558 		return -EINVAL;
2559 
2560 	device_pm_lock();
2561 	new_parent = get_device(new_parent);
2562 	new_parent_kobj = get_device_parent(dev, new_parent);
2563 
2564 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
2565 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
2566 	error = kobject_move(&dev->kobj, new_parent_kobj);
2567 	if (error) {
2568 		cleanup_glue_dir(dev, new_parent_kobj);
2569 		put_device(new_parent);
2570 		goto out;
2571 	}
2572 	old_parent = dev->parent;
2573 	dev->parent = new_parent;
2574 	if (old_parent)
2575 		klist_remove(&dev->p->knode_parent);
2576 	if (new_parent) {
2577 		klist_add_tail(&dev->p->knode_parent,
2578 			       &new_parent->p->klist_children);
2579 		set_dev_node(dev, dev_to_node(new_parent));
2580 	}
2581 
2582 	if (dev->class) {
2583 		error = device_move_class_links(dev, old_parent, new_parent);
2584 		if (error) {
2585 			/* We ignore errors on cleanup since we're hosed anyway... */
2586 			device_move_class_links(dev, new_parent, old_parent);
2587 			if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
2588 				if (new_parent)
2589 					klist_remove(&dev->p->knode_parent);
2590 				dev->parent = old_parent;
2591 				if (old_parent) {
2592 					klist_add_tail(&dev->p->knode_parent,
2593 						       &old_parent->p->klist_children);
2594 					set_dev_node(dev, dev_to_node(old_parent));
2595 				}
2596 			}
2597 			cleanup_glue_dir(dev, new_parent_kobj);
2598 			put_device(new_parent);
2599 			goto out;
2600 		}
2601 	}
2602 	switch (dpm_order) {
2603 	case DPM_ORDER_NONE:
2604 		break;
2605 	case DPM_ORDER_DEV_AFTER_PARENT:
2606 		device_pm_move_after(dev, new_parent);
2607 		devices_kset_move_after(dev, new_parent);
2608 		break;
2609 	case DPM_ORDER_PARENT_BEFORE_DEV:
2610 		device_pm_move_before(new_parent, dev);
2611 		devices_kset_move_before(new_parent, dev);
2612 		break;
2613 	case DPM_ORDER_DEV_LAST:
2614 		device_pm_move_last(dev);
2615 		devices_kset_move_last(dev);
2616 		break;
2617 	}
2618 
2619 	put_device(old_parent);
2620 out:
2621 	device_pm_unlock();
2622 	put_device(dev);
2623 	return error;
2624 }
2625 EXPORT_SYMBOL_GPL(device_move);
2626 
2627 /**
2628  * device_shutdown - call ->shutdown() on each device to shutdown.
2629  */
2630 void device_shutdown(void)
2631 {
2632 	struct device *dev, *parent;
2633 
2634 	spin_lock(&devices_kset->list_lock);
2635 	/*
2636 	 * Walk the devices list backward, shutting down each in turn.
2637 	 * Beware that device unplug events may also start pulling
2638 	 * devices offline, even as the system is shutting down.
2639 	 */
2640 	while (!list_empty(&devices_kset->list)) {
2641 		dev = list_entry(devices_kset->list.prev, struct device,
2642 				kobj.entry);
2643 
2644 		/*
2645 		 * hold reference count of device's parent to
2646 		 * prevent it from being freed because parent's
2647 		 * lock is to be held
2648 		 */
2649 		parent = get_device(dev->parent);
2650 		get_device(dev);
2651 		/*
2652 		 * Make sure the device is off the kset list, in the
2653 		 * event that dev->*->shutdown() doesn't remove it.
2654 		 */
2655 		list_del_init(&dev->kobj.entry);
2656 		spin_unlock(&devices_kset->list_lock);
2657 
2658 		/* hold lock to avoid race with probe/release */
2659 		if (parent)
2660 			device_lock(parent);
2661 		device_lock(dev);
2662 
2663 		/* Don't allow any more runtime suspends */
2664 		pm_runtime_get_noresume(dev);
2665 		pm_runtime_barrier(dev);
2666 
2667 		if (dev->class && dev->class->shutdown) {
2668 			if (initcall_debug)
2669 				dev_info(dev, "shutdown\n");
2670 			dev->class->shutdown(dev);
2671 		} else if (dev->bus && dev->bus->shutdown) {
2672 			if (initcall_debug)
2673 				dev_info(dev, "shutdown\n");
2674 			dev->bus->shutdown(dev);
2675 		} else if (dev->driver && dev->driver->shutdown) {
2676 			if (initcall_debug)
2677 				dev_info(dev, "shutdown\n");
2678 			dev->driver->shutdown(dev);
2679 		}
2680 
2681 		device_unlock(dev);
2682 		if (parent)
2683 			device_unlock(parent);
2684 
2685 		put_device(dev);
2686 		put_device(parent);
2687 
2688 		spin_lock(&devices_kset->list_lock);
2689 	}
2690 	spin_unlock(&devices_kset->list_lock);
2691 }
2692 
2693 /*
2694  * Device logging functions
2695  */
2696 
2697 #ifdef CONFIG_PRINTK
2698 static int
2699 create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
2700 {
2701 	const char *subsys;
2702 	size_t pos = 0;
2703 
2704 	if (dev->class)
2705 		subsys = dev->class->name;
2706 	else if (dev->bus)
2707 		subsys = dev->bus->name;
2708 	else
2709 		return 0;
2710 
2711 	pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);
2712 	if (pos >= hdrlen)
2713 		goto overflow;
2714 
2715 	/*
2716 	 * Add device identifier DEVICE=:
2717 	 *   b12:8         block dev_t
2718 	 *   c127:3        char dev_t
2719 	 *   n8            netdev ifindex
2720 	 *   +sound:card0  subsystem:devname
2721 	 */
2722 	if (MAJOR(dev->devt)) {
2723 		char c;
2724 
2725 		if (strcmp(subsys, "block") == 0)
2726 			c = 'b';
2727 		else
2728 			c = 'c';
2729 		pos++;
2730 		pos += snprintf(hdr + pos, hdrlen - pos,
2731 				"DEVICE=%c%u:%u",
2732 				c, MAJOR(dev->devt), MINOR(dev->devt));
2733 	} else if (strcmp(subsys, "net") == 0) {
2734 		struct net_device *net = to_net_dev(dev);
2735 
2736 		pos++;
2737 		pos += snprintf(hdr + pos, hdrlen - pos,
2738 				"DEVICE=n%u", net->ifindex);
2739 	} else {
2740 		pos++;
2741 		pos += snprintf(hdr + pos, hdrlen - pos,
2742 				"DEVICE=+%s:%s", subsys, dev_name(dev));
2743 	}
2744 
2745 	if (pos >= hdrlen)
2746 		goto overflow;
2747 
2748 	return pos;
2749 
2750 overflow:
2751 	dev_WARN(dev, "device/subsystem name too long");
2752 	return 0;
2753 }
2754 
2755 int dev_vprintk_emit(int level, const struct device *dev,
2756 		     const char *fmt, va_list args)
2757 {
2758 	char hdr[128];
2759 	size_t hdrlen;
2760 
2761 	hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));
2762 
2763 	return vprintk_emit(0, level, hdrlen ? hdr : NULL, hdrlen, fmt, args);
2764 }
2765 EXPORT_SYMBOL(dev_vprintk_emit);
2766 
2767 int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
2768 {
2769 	va_list args;
2770 	int r;
2771 
2772 	va_start(args, fmt);
2773 
2774 	r = dev_vprintk_emit(level, dev, fmt, args);
2775 
2776 	va_end(args);
2777 
2778 	return r;
2779 }
2780 EXPORT_SYMBOL(dev_printk_emit);
2781 
2782 static void __dev_printk(const char *level, const struct device *dev,
2783 			struct va_format *vaf)
2784 {
2785 	if (dev)
2786 		dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
2787 				dev_driver_string(dev), dev_name(dev), vaf);
2788 	else
2789 		printk("%s(NULL device *): %pV", level, vaf);
2790 }
2791 
2792 void dev_printk(const char *level, const struct device *dev,
2793 		const char *fmt, ...)
2794 {
2795 	struct va_format vaf;
2796 	va_list args;
2797 
2798 	va_start(args, fmt);
2799 
2800 	vaf.fmt = fmt;
2801 	vaf.va = &args;
2802 
2803 	__dev_printk(level, dev, &vaf);
2804 
2805 	va_end(args);
2806 }
2807 EXPORT_SYMBOL(dev_printk);
2808 
2809 #define define_dev_printk_level(func, kern_level)		\
2810 void func(const struct device *dev, const char *fmt, ...)	\
2811 {								\
2812 	struct va_format vaf;					\
2813 	va_list args;						\
2814 								\
2815 	va_start(args, fmt);					\
2816 								\
2817 	vaf.fmt = fmt;						\
2818 	vaf.va = &args;						\
2819 								\
2820 	__dev_printk(kern_level, dev, &vaf);			\
2821 								\
2822 	va_end(args);						\
2823 }								\
2824 EXPORT_SYMBOL(func);
2825 
2826 define_dev_printk_level(dev_emerg, KERN_EMERG);
2827 define_dev_printk_level(dev_alert, KERN_ALERT);
2828 define_dev_printk_level(dev_crit, KERN_CRIT);
2829 define_dev_printk_level(dev_err, KERN_ERR);
2830 define_dev_printk_level(dev_warn, KERN_WARNING);
2831 define_dev_printk_level(dev_notice, KERN_NOTICE);
2832 define_dev_printk_level(_dev_info, KERN_INFO);
2833 
2834 #endif
2835 
2836 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
2837 {
2838 	return fwnode && !IS_ERR(fwnode->secondary);
2839 }
2840 
2841 /**
2842  * set_primary_fwnode - Change the primary firmware node of a given device.
2843  * @dev: Device to handle.
2844  * @fwnode: New primary firmware node of the device.
2845  *
2846  * Set the device's firmware node pointer to @fwnode, but if a secondary
2847  * firmware node of the device is present, preserve it.
2848  */
2849 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
2850 {
2851 	if (fwnode) {
2852 		struct fwnode_handle *fn = dev->fwnode;
2853 
2854 		if (fwnode_is_primary(fn))
2855 			fn = fn->secondary;
2856 
2857 		if (fn) {
2858 			WARN_ON(fwnode->secondary);
2859 			fwnode->secondary = fn;
2860 		}
2861 		dev->fwnode = fwnode;
2862 	} else {
2863 		dev->fwnode = fwnode_is_primary(dev->fwnode) ?
2864 			dev->fwnode->secondary : NULL;
2865 	}
2866 }
2867 EXPORT_SYMBOL_GPL(set_primary_fwnode);
2868 
2869 /**
2870  * set_secondary_fwnode - Change the secondary firmware node of a given device.
2871  * @dev: Device to handle.
2872  * @fwnode: New secondary firmware node of the device.
2873  *
2874  * If a primary firmware node of the device is present, set its secondary
2875  * pointer to @fwnode.  Otherwise, set the device's firmware node pointer to
2876  * @fwnode.
2877  */
2878 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
2879 {
2880 	if (fwnode)
2881 		fwnode->secondary = ERR_PTR(-ENODEV);
2882 
2883 	if (fwnode_is_primary(dev->fwnode))
2884 		dev->fwnode->secondary = fwnode;
2885 	else
2886 		dev->fwnode = fwnode;
2887 }
2888 
2889 /**
2890  * device_set_of_node_from_dev - reuse device-tree node of another device
2891  * @dev: device whose device-tree node is being set
2892  * @dev2: device whose device-tree node is being reused
2893  *
2894  * Takes another reference to the new device-tree node after first dropping
2895  * any reference held to the old node.
2896  */
2897 void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
2898 {
2899 	of_node_put(dev->of_node);
2900 	dev->of_node = of_node_get(dev2->of_node);
2901 	dev->of_node_reused = true;
2902 }
2903 EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
2904