xref: /linux/drivers/base/core.c (revision 170aafe35cb98e0f3fbacb446ea86389fbce22ea)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * drivers/base/core.c - core driver model code (device registration, etc)
4  *
5  * Copyright (c) 2002-3 Patrick Mochel
6  * Copyright (c) 2002-3 Open Source Development Labs
7  * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
8  * Copyright (c) 2006 Novell, Inc.
9  */
10 
11 #include <linux/acpi.h>
12 #include <linux/cpufreq.h>
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/fwnode.h>
16 #include <linux/init.h>
17 #include <linux/kstrtox.h>
18 #include <linux/module.h>
19 #include <linux/slab.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/blkdev.h>
25 #include <linux/mutex.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/netdevice.h>
28 #include <linux/rcupdate.h>
29 #include <linux/sched/signal.h>
30 #include <linux/sched/mm.h>
31 #include <linux/string_helpers.h>
32 #include <linux/swiotlb.h>
33 #include <linux/sysfs.h>
34 #include <linux/dma-map-ops.h> /* for dma_default_coherent */
35 
36 #include "base.h"
37 #include "physical_location.h"
38 #include "power/power.h"
39 
40 /* Device links support. */
41 static LIST_HEAD(deferred_sync);
42 static unsigned int defer_sync_state_count = 1;
43 static DEFINE_MUTEX(fwnode_link_lock);
44 static bool fw_devlink_is_permissive(void);
45 static void __fw_devlink_link_to_consumers(struct device *dev);
46 static bool fw_devlink_drv_reg_done;
47 static bool fw_devlink_best_effort;
48 static struct workqueue_struct *device_link_wq;
49 
50 /**
51  * __fwnode_link_add - Create a link between two fwnode_handles.
52  * @con: Consumer end of the link.
53  * @sup: Supplier end of the link.
54  * @flags: Link flags.
55  *
56  * Create a fwnode link between fwnode handles @con and @sup. The fwnode link
57  * represents the detail that the firmware lists @sup fwnode as supplying a
58  * resource to @con.
59  *
60  * The driver core will use the fwnode link to create a device link between the
61  * two device objects corresponding to @con and @sup when they are created. The
62  * driver core will automatically delete the fwnode link between @con and @sup
63  * after doing that.
64  *
65  * Attempts to create duplicate links between the same pair of fwnode handles
66  * are ignored and there is no reference counting.
67  */
68 static int __fwnode_link_add(struct fwnode_handle *con,
69 			     struct fwnode_handle *sup, u8 flags)
70 {
71 	struct fwnode_link *link;
72 
73 	list_for_each_entry(link, &sup->consumers, s_hook)
74 		if (link->consumer == con) {
75 			link->flags |= flags;
76 			return 0;
77 		}
78 
79 	link = kzalloc(sizeof(*link), GFP_KERNEL);
80 	if (!link)
81 		return -ENOMEM;
82 
83 	link->supplier = sup;
84 	INIT_LIST_HEAD(&link->s_hook);
85 	link->consumer = con;
86 	INIT_LIST_HEAD(&link->c_hook);
87 	link->flags = flags;
88 
89 	list_add(&link->s_hook, &sup->consumers);
90 	list_add(&link->c_hook, &con->suppliers);
91 	pr_debug("%pfwf Linked as a fwnode consumer to %pfwf\n",
92 		 con, sup);
93 
94 	return 0;
95 }
96 
97 int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup,
98 		    u8 flags)
99 {
100 	int ret;
101 
102 	mutex_lock(&fwnode_link_lock);
103 	ret = __fwnode_link_add(con, sup, flags);
104 	mutex_unlock(&fwnode_link_lock);
105 	return ret;
106 }
107 
108 /**
109  * __fwnode_link_del - Delete a link between two fwnode_handles.
110  * @link: the fwnode_link to be deleted
111  *
112  * The fwnode_link_lock needs to be held when this function is called.
113  */
114 static void __fwnode_link_del(struct fwnode_link *link)
115 {
116 	pr_debug("%pfwf Dropping the fwnode link to %pfwf\n",
117 		 link->consumer, link->supplier);
118 	list_del(&link->s_hook);
119 	list_del(&link->c_hook);
120 	kfree(link);
121 }
122 
123 /**
124  * __fwnode_link_cycle - Mark a fwnode link as being part of a cycle.
125  * @link: the fwnode_link to be marked
126  *
127  * The fwnode_link_lock needs to be held when this function is called.
128  */
129 static void __fwnode_link_cycle(struct fwnode_link *link)
130 {
131 	pr_debug("%pfwf: cycle: depends on %pfwf\n",
132 		 link->consumer, link->supplier);
133 	link->flags |= FWLINK_FLAG_CYCLE;
134 }
135 
136 /**
137  * fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.
138  * @fwnode: fwnode whose supplier links need to be deleted
139  *
140  * Deletes all supplier links connecting directly to @fwnode.
141  */
142 static void fwnode_links_purge_suppliers(struct fwnode_handle *fwnode)
143 {
144 	struct fwnode_link *link, *tmp;
145 
146 	mutex_lock(&fwnode_link_lock);
147 	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook)
148 		__fwnode_link_del(link);
149 	mutex_unlock(&fwnode_link_lock);
150 }
151 
152 /**
153  * fwnode_links_purge_consumers - Delete all consumer links of fwnode_handle.
154  * @fwnode: fwnode whose consumer links need to be deleted
155  *
156  * Deletes all consumer links connecting directly to @fwnode.
157  */
158 static void fwnode_links_purge_consumers(struct fwnode_handle *fwnode)
159 {
160 	struct fwnode_link *link, *tmp;
161 
162 	mutex_lock(&fwnode_link_lock);
163 	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook)
164 		__fwnode_link_del(link);
165 	mutex_unlock(&fwnode_link_lock);
166 }
167 
168 /**
169  * fwnode_links_purge - Delete all links connected to a fwnode_handle.
170  * @fwnode: fwnode whose links needs to be deleted
171  *
172  * Deletes all links connecting directly to a fwnode.
173  */
174 void fwnode_links_purge(struct fwnode_handle *fwnode)
175 {
176 	fwnode_links_purge_suppliers(fwnode);
177 	fwnode_links_purge_consumers(fwnode);
178 }
179 
180 void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode)
181 {
182 	struct fwnode_handle *child;
183 
184 	/* Don't purge consumer links of an added child */
185 	if (fwnode->dev)
186 		return;
187 
188 	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
189 	fwnode_links_purge_consumers(fwnode);
190 
191 	fwnode_for_each_available_child_node(fwnode, child)
192 		fw_devlink_purge_absent_suppliers(child);
193 }
194 EXPORT_SYMBOL_GPL(fw_devlink_purge_absent_suppliers);
195 
196 /**
197  * __fwnode_links_move_consumers - Move consumer from @from to @to fwnode_handle
198  * @from: move consumers away from this fwnode
199  * @to: move consumers to this fwnode
200  *
201  * Move all consumer links from @from fwnode to @to fwnode.
202  */
203 static void __fwnode_links_move_consumers(struct fwnode_handle *from,
204 					  struct fwnode_handle *to)
205 {
206 	struct fwnode_link *link, *tmp;
207 
208 	list_for_each_entry_safe(link, tmp, &from->consumers, s_hook) {
209 		__fwnode_link_add(link->consumer, to, link->flags);
210 		__fwnode_link_del(link);
211 	}
212 }
213 
214 /**
215  * __fw_devlink_pickup_dangling_consumers - Pick up dangling consumers
216  * @fwnode: fwnode from which to pick up dangling consumers
217  * @new_sup: fwnode of new supplier
218  *
219  * If the @fwnode has a corresponding struct device and the device supports
220  * probing (that is, added to a bus), then we want to let fw_devlink create
221  * MANAGED device links to this device, so leave @fwnode and its descendant's
222  * fwnode links alone.
223  *
224  * Otherwise, move its consumers to the new supplier @new_sup.
225  */
226 static void __fw_devlink_pickup_dangling_consumers(struct fwnode_handle *fwnode,
227 						   struct fwnode_handle *new_sup)
228 {
229 	struct fwnode_handle *child;
230 
231 	if (fwnode->dev && fwnode->dev->bus)
232 		return;
233 
234 	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
235 	__fwnode_links_move_consumers(fwnode, new_sup);
236 
237 	fwnode_for_each_available_child_node(fwnode, child)
238 		__fw_devlink_pickup_dangling_consumers(child, new_sup);
239 }
240 
241 static DEFINE_MUTEX(device_links_lock);
242 DEFINE_STATIC_SRCU(device_links_srcu);
243 
244 static inline void device_links_write_lock(void)
245 {
246 	mutex_lock(&device_links_lock);
247 }
248 
249 static inline void device_links_write_unlock(void)
250 {
251 	mutex_unlock(&device_links_lock);
252 }
253 
254 int device_links_read_lock(void) __acquires(&device_links_srcu)
255 {
256 	return srcu_read_lock(&device_links_srcu);
257 }
258 
259 void device_links_read_unlock(int idx) __releases(&device_links_srcu)
260 {
261 	srcu_read_unlock(&device_links_srcu, idx);
262 }
263 
264 int device_links_read_lock_held(void)
265 {
266 	return srcu_read_lock_held(&device_links_srcu);
267 }
268 
269 static void device_link_synchronize_removal(void)
270 {
271 	synchronize_srcu(&device_links_srcu);
272 }
273 
274 static void device_link_remove_from_lists(struct device_link *link)
275 {
276 	list_del_rcu(&link->s_node);
277 	list_del_rcu(&link->c_node);
278 }
279 
280 static bool device_is_ancestor(struct device *dev, struct device *target)
281 {
282 	while (target->parent) {
283 		target = target->parent;
284 		if (dev == target)
285 			return true;
286 	}
287 	return false;
288 }
289 
290 #define DL_MARKER_FLAGS		(DL_FLAG_INFERRED | \
291 				 DL_FLAG_CYCLE | \
292 				 DL_FLAG_MANAGED)
293 static inline bool device_link_flag_is_sync_state_only(u32 flags)
294 {
295 	return (flags & ~DL_MARKER_FLAGS) == DL_FLAG_SYNC_STATE_ONLY;
296 }
297 
298 /**
299  * device_is_dependent - Check if one device depends on another one
300  * @dev: Device to check dependencies for.
301  * @target: Device to check against.
302  *
303  * Check if @target depends on @dev or any device dependent on it (its child or
304  * its consumer etc).  Return 1 if that is the case or 0 otherwise.
305  */
306 static int device_is_dependent(struct device *dev, void *target)
307 {
308 	struct device_link *link;
309 	int ret;
310 
311 	/*
312 	 * The "ancestors" check is needed to catch the case when the target
313 	 * device has not been completely initialized yet and it is still
314 	 * missing from the list of children of its parent device.
315 	 */
316 	if (dev == target || device_is_ancestor(dev, target))
317 		return 1;
318 
319 	ret = device_for_each_child(dev, target, device_is_dependent);
320 	if (ret)
321 		return ret;
322 
323 	list_for_each_entry(link, &dev->links.consumers, s_node) {
324 		if (device_link_flag_is_sync_state_only(link->flags))
325 			continue;
326 
327 		if (link->consumer == target)
328 			return 1;
329 
330 		ret = device_is_dependent(link->consumer, target);
331 		if (ret)
332 			break;
333 	}
334 	return ret;
335 }
336 
337 static void device_link_init_status(struct device_link *link,
338 				    struct device *consumer,
339 				    struct device *supplier)
340 {
341 	switch (supplier->links.status) {
342 	case DL_DEV_PROBING:
343 		switch (consumer->links.status) {
344 		case DL_DEV_PROBING:
345 			/*
346 			 * A consumer driver can create a link to a supplier
347 			 * that has not completed its probing yet as long as it
348 			 * knows that the supplier is already functional (for
349 			 * example, it has just acquired some resources from the
350 			 * supplier).
351 			 */
352 			link->status = DL_STATE_CONSUMER_PROBE;
353 			break;
354 		default:
355 			link->status = DL_STATE_DORMANT;
356 			break;
357 		}
358 		break;
359 	case DL_DEV_DRIVER_BOUND:
360 		switch (consumer->links.status) {
361 		case DL_DEV_PROBING:
362 			link->status = DL_STATE_CONSUMER_PROBE;
363 			break;
364 		case DL_DEV_DRIVER_BOUND:
365 			link->status = DL_STATE_ACTIVE;
366 			break;
367 		default:
368 			link->status = DL_STATE_AVAILABLE;
369 			break;
370 		}
371 		break;
372 	case DL_DEV_UNBINDING:
373 		link->status = DL_STATE_SUPPLIER_UNBIND;
374 		break;
375 	default:
376 		link->status = DL_STATE_DORMANT;
377 		break;
378 	}
379 }
380 
381 static int device_reorder_to_tail(struct device *dev, void *not_used)
382 {
383 	struct device_link *link;
384 
385 	/*
386 	 * Devices that have not been registered yet will be put to the ends
387 	 * of the lists during the registration, so skip them here.
388 	 */
389 	if (device_is_registered(dev))
390 		devices_kset_move_last(dev);
391 
392 	if (device_pm_initialized(dev))
393 		device_pm_move_last(dev);
394 
395 	device_for_each_child(dev, NULL, device_reorder_to_tail);
396 	list_for_each_entry(link, &dev->links.consumers, s_node) {
397 		if (device_link_flag_is_sync_state_only(link->flags))
398 			continue;
399 		device_reorder_to_tail(link->consumer, NULL);
400 	}
401 
402 	return 0;
403 }
404 
405 /**
406  * device_pm_move_to_tail - Move set of devices to the end of device lists
407  * @dev: Device to move
408  *
409  * This is a device_reorder_to_tail() wrapper taking the requisite locks.
410  *
411  * It moves the @dev along with all of its children and all of its consumers
412  * to the ends of the device_kset and dpm_list, recursively.
413  */
414 void device_pm_move_to_tail(struct device *dev)
415 {
416 	int idx;
417 
418 	idx = device_links_read_lock();
419 	device_pm_lock();
420 	device_reorder_to_tail(dev, NULL);
421 	device_pm_unlock();
422 	device_links_read_unlock(idx);
423 }
424 
425 #define to_devlink(dev)	container_of((dev), struct device_link, link_dev)
426 
427 static ssize_t status_show(struct device *dev,
428 			   struct device_attribute *attr, char *buf)
429 {
430 	const char *output;
431 
432 	switch (to_devlink(dev)->status) {
433 	case DL_STATE_NONE:
434 		output = "not tracked";
435 		break;
436 	case DL_STATE_DORMANT:
437 		output = "dormant";
438 		break;
439 	case DL_STATE_AVAILABLE:
440 		output = "available";
441 		break;
442 	case DL_STATE_CONSUMER_PROBE:
443 		output = "consumer probing";
444 		break;
445 	case DL_STATE_ACTIVE:
446 		output = "active";
447 		break;
448 	case DL_STATE_SUPPLIER_UNBIND:
449 		output = "supplier unbinding";
450 		break;
451 	default:
452 		output = "unknown";
453 		break;
454 	}
455 
456 	return sysfs_emit(buf, "%s\n", output);
457 }
458 static DEVICE_ATTR_RO(status);
459 
460 static ssize_t auto_remove_on_show(struct device *dev,
461 				   struct device_attribute *attr, char *buf)
462 {
463 	struct device_link *link = to_devlink(dev);
464 	const char *output;
465 
466 	if (link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
467 		output = "supplier unbind";
468 	else if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
469 		output = "consumer unbind";
470 	else
471 		output = "never";
472 
473 	return sysfs_emit(buf, "%s\n", output);
474 }
475 static DEVICE_ATTR_RO(auto_remove_on);
476 
477 static ssize_t runtime_pm_show(struct device *dev,
478 			       struct device_attribute *attr, char *buf)
479 {
480 	struct device_link *link = to_devlink(dev);
481 
482 	return sysfs_emit(buf, "%d\n", !!(link->flags & DL_FLAG_PM_RUNTIME));
483 }
484 static DEVICE_ATTR_RO(runtime_pm);
485 
486 static ssize_t sync_state_only_show(struct device *dev,
487 				    struct device_attribute *attr, char *buf)
488 {
489 	struct device_link *link = to_devlink(dev);
490 
491 	return sysfs_emit(buf, "%d\n",
492 			  !!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
493 }
494 static DEVICE_ATTR_RO(sync_state_only);
495 
496 static struct attribute *devlink_attrs[] = {
497 	&dev_attr_status.attr,
498 	&dev_attr_auto_remove_on.attr,
499 	&dev_attr_runtime_pm.attr,
500 	&dev_attr_sync_state_only.attr,
501 	NULL,
502 };
503 ATTRIBUTE_GROUPS(devlink);
504 
505 static void device_link_release_fn(struct work_struct *work)
506 {
507 	struct device_link *link = container_of(work, struct device_link, rm_work);
508 
509 	/* Ensure that all references to the link object have been dropped. */
510 	device_link_synchronize_removal();
511 
512 	pm_runtime_release_supplier(link);
513 	/*
514 	 * If supplier_preactivated is set, the link has been dropped between
515 	 * the pm_runtime_get_suppliers() and pm_runtime_put_suppliers() calls
516 	 * in __driver_probe_device().  In that case, drop the supplier's
517 	 * PM-runtime usage counter to remove the reference taken by
518 	 * pm_runtime_get_suppliers().
519 	 */
520 	if (link->supplier_preactivated)
521 		pm_runtime_put_noidle(link->supplier);
522 
523 	pm_request_idle(link->supplier);
524 
525 	put_device(link->consumer);
526 	put_device(link->supplier);
527 	kfree(link);
528 }
529 
530 static void devlink_dev_release(struct device *dev)
531 {
532 	struct device_link *link = to_devlink(dev);
533 
534 	INIT_WORK(&link->rm_work, device_link_release_fn);
535 	/*
536 	 * It may take a while to complete this work because of the SRCU
537 	 * synchronization in device_link_release_fn() and if the consumer or
538 	 * supplier devices get deleted when it runs, so put it into the
539 	 * dedicated workqueue.
540 	 */
541 	queue_work(device_link_wq, &link->rm_work);
542 }
543 
544 /**
545  * device_link_wait_removal - Wait for ongoing devlink removal jobs to terminate
546  */
547 void device_link_wait_removal(void)
548 {
549 	/*
550 	 * devlink removal jobs are queued in the dedicated work queue.
551 	 * To be sure that all removal jobs are terminated, ensure that any
552 	 * scheduled work has run to completion.
553 	 */
554 	flush_workqueue(device_link_wq);
555 }
556 EXPORT_SYMBOL_GPL(device_link_wait_removal);
557 
558 static struct class devlink_class = {
559 	.name = "devlink",
560 	.dev_groups = devlink_groups,
561 	.dev_release = devlink_dev_release,
562 };
563 
564 static int devlink_add_symlinks(struct device *dev)
565 {
566 	int ret;
567 	size_t len;
568 	struct device_link *link = to_devlink(dev);
569 	struct device *sup = link->supplier;
570 	struct device *con = link->consumer;
571 	char *buf;
572 
573 	len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
574 		  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
575 	len += strlen(":");
576 	len += strlen("supplier:") + 1;
577 	buf = kzalloc(len, GFP_KERNEL);
578 	if (!buf)
579 		return -ENOMEM;
580 
581 	ret = sysfs_create_link(&link->link_dev.kobj, &sup->kobj, "supplier");
582 	if (ret)
583 		goto out;
584 
585 	ret = sysfs_create_link(&link->link_dev.kobj, &con->kobj, "consumer");
586 	if (ret)
587 		goto err_con;
588 
589 	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
590 	ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf);
591 	if (ret)
592 		goto err_con_dev;
593 
594 	snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
595 	ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf);
596 	if (ret)
597 		goto err_sup_dev;
598 
599 	goto out;
600 
601 err_sup_dev:
602 	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
603 	sysfs_remove_link(&sup->kobj, buf);
604 err_con_dev:
605 	sysfs_remove_link(&link->link_dev.kobj, "consumer");
606 err_con:
607 	sysfs_remove_link(&link->link_dev.kobj, "supplier");
608 out:
609 	kfree(buf);
610 	return ret;
611 }
612 
613 static void devlink_remove_symlinks(struct device *dev)
614 {
615 	struct device_link *link = to_devlink(dev);
616 	size_t len;
617 	struct device *sup = link->supplier;
618 	struct device *con = link->consumer;
619 	char *buf;
620 
621 	sysfs_remove_link(&link->link_dev.kobj, "consumer");
622 	sysfs_remove_link(&link->link_dev.kobj, "supplier");
623 
624 	len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
625 		  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
626 	len += strlen(":");
627 	len += strlen("supplier:") + 1;
628 	buf = kzalloc(len, GFP_KERNEL);
629 	if (!buf) {
630 		WARN(1, "Unable to properly free device link symlinks!\n");
631 		return;
632 	}
633 
634 	if (device_is_registered(con)) {
635 		snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
636 		sysfs_remove_link(&con->kobj, buf);
637 	}
638 	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
639 	sysfs_remove_link(&sup->kobj, buf);
640 	kfree(buf);
641 }
642 
643 static struct class_interface devlink_class_intf = {
644 	.class = &devlink_class,
645 	.add_dev = devlink_add_symlinks,
646 	.remove_dev = devlink_remove_symlinks,
647 };
648 
649 static int __init devlink_class_init(void)
650 {
651 	int ret;
652 
653 	ret = class_register(&devlink_class);
654 	if (ret)
655 		return ret;
656 
657 	ret = class_interface_register(&devlink_class_intf);
658 	if (ret)
659 		class_unregister(&devlink_class);
660 
661 	return ret;
662 }
663 postcore_initcall(devlink_class_init);
664 
665 #define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
666 			       DL_FLAG_AUTOREMOVE_SUPPLIER | \
667 			       DL_FLAG_AUTOPROBE_CONSUMER  | \
668 			       DL_FLAG_SYNC_STATE_ONLY | \
669 			       DL_FLAG_INFERRED | \
670 			       DL_FLAG_CYCLE)
671 
672 #define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
673 			    DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
674 
675 /**
676  * device_link_add - Create a link between two devices.
677  * @consumer: Consumer end of the link.
678  * @supplier: Supplier end of the link.
679  * @flags: Link flags.
680  *
681  * The caller is responsible for the proper synchronization of the link creation
682  * with runtime PM.  First, setting the DL_FLAG_PM_RUNTIME flag will cause the
683  * runtime PM framework to take the link into account.  Second, if the
684  * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
685  * be forced into the active meta state and reference-counted upon the creation
686  * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
687  * ignored.
688  *
689  * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
690  * expected to release the link returned by it directly with the help of either
691  * device_link_del() or device_link_remove().
692  *
693  * If that flag is not set, however, the caller of this function is handing the
694  * management of the link over to the driver core entirely and its return value
695  * can only be used to check whether or not the link is present.  In that case,
696  * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
697  * flags can be used to indicate to the driver core when the link can be safely
698  * deleted.  Namely, setting one of them in @flags indicates to the driver core
699  * that the link is not going to be used (by the given caller of this function)
700  * after unbinding the consumer or supplier driver, respectively, from its
701  * device, so the link can be deleted at that point.  If none of them is set,
702  * the link will be maintained until one of the devices pointed to by it (either
703  * the consumer or the supplier) is unregistered.
704  *
705  * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
706  * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
707  * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
708  * be used to request the driver core to automatically probe for a consumer
709  * driver after successfully binding a driver to the supplier device.
710  *
711  * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
712  * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
713  * the same time is invalid and will cause NULL to be returned upfront.
714  * However, if a device link between the given @consumer and @supplier pair
715  * exists already when this function is called for them, the existing link will
716  * be returned regardless of its current type and status (the link's flags may
717  * be modified then).  The caller of this function is then expected to treat
718  * the link as though it has just been created, so (in particular) if
719  * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
720  * explicitly when not needed any more (as stated above).
721  *
722  * A side effect of the link creation is re-ordering of dpm_list and the
723  * devices_kset list by moving the consumer device and all devices depending
724  * on it to the ends of these lists (that does not happen to devices that have
725  * not been registered when this function is called).
726  *
727  * The supplier device is required to be registered when this function is called
728  * and NULL will be returned if that is not the case.  The consumer device need
729  * not be registered, however.
730  */
731 struct device_link *device_link_add(struct device *consumer,
732 				    struct device *supplier, u32 flags)
733 {
734 	struct device_link *link;
735 
736 	if (!consumer || !supplier || consumer == supplier ||
737 	    flags & ~DL_ADD_VALID_FLAGS ||
738 	    (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
739 	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
740 	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
741 		      DL_FLAG_AUTOREMOVE_SUPPLIER)))
742 		return NULL;
743 
744 	if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
745 		if (pm_runtime_get_sync(supplier) < 0) {
746 			pm_runtime_put_noidle(supplier);
747 			return NULL;
748 		}
749 	}
750 
751 	if (!(flags & DL_FLAG_STATELESS))
752 		flags |= DL_FLAG_MANAGED;
753 
754 	if (flags & DL_FLAG_SYNC_STATE_ONLY &&
755 	    !device_link_flag_is_sync_state_only(flags))
756 		return NULL;
757 
758 	device_links_write_lock();
759 	device_pm_lock();
760 
761 	/*
762 	 * If the supplier has not been fully registered yet or there is a
763 	 * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
764 	 * the supplier already in the graph, return NULL. If the link is a
765 	 * SYNC_STATE_ONLY link, we don't check for reverse dependencies
766 	 * because it only affects sync_state() callbacks.
767 	 */
768 	if (!device_pm_initialized(supplier)
769 	    || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
770 		  device_is_dependent(consumer, supplier))) {
771 		link = NULL;
772 		goto out;
773 	}
774 
775 	/*
776 	 * SYNC_STATE_ONLY links are useless once a consumer device has probed.
777 	 * So, only create it if the consumer hasn't probed yet.
778 	 */
779 	if (flags & DL_FLAG_SYNC_STATE_ONLY &&
780 	    consumer->links.status != DL_DEV_NO_DRIVER &&
781 	    consumer->links.status != DL_DEV_PROBING) {
782 		link = NULL;
783 		goto out;
784 	}
785 
786 	/*
787 	 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
788 	 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
789 	 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
790 	 */
791 	if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
792 		flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
793 
794 	list_for_each_entry(link, &supplier->links.consumers, s_node) {
795 		if (link->consumer != consumer)
796 			continue;
797 
798 		if (link->flags & DL_FLAG_INFERRED &&
799 		    !(flags & DL_FLAG_INFERRED))
800 			link->flags &= ~DL_FLAG_INFERRED;
801 
802 		if (flags & DL_FLAG_PM_RUNTIME) {
803 			if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
804 				pm_runtime_new_link(consumer);
805 				link->flags |= DL_FLAG_PM_RUNTIME;
806 			}
807 			if (flags & DL_FLAG_RPM_ACTIVE)
808 				refcount_inc(&link->rpm_active);
809 		}
810 
811 		if (flags & DL_FLAG_STATELESS) {
812 			kref_get(&link->kref);
813 			if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
814 			    !(link->flags & DL_FLAG_STATELESS)) {
815 				link->flags |= DL_FLAG_STATELESS;
816 				goto reorder;
817 			} else {
818 				link->flags |= DL_FLAG_STATELESS;
819 				goto out;
820 			}
821 		}
822 
823 		/*
824 		 * If the life time of the link following from the new flags is
825 		 * longer than indicated by the flags of the existing link,
826 		 * update the existing link to stay around longer.
827 		 */
828 		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
829 			if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
830 				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
831 				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
832 			}
833 		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
834 			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
835 					 DL_FLAG_AUTOREMOVE_SUPPLIER);
836 		}
837 		if (!(link->flags & DL_FLAG_MANAGED)) {
838 			kref_get(&link->kref);
839 			link->flags |= DL_FLAG_MANAGED;
840 			device_link_init_status(link, consumer, supplier);
841 		}
842 		if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
843 		    !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
844 			link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
845 			goto reorder;
846 		}
847 
848 		goto out;
849 	}
850 
851 	link = kzalloc(sizeof(*link), GFP_KERNEL);
852 	if (!link)
853 		goto out;
854 
855 	refcount_set(&link->rpm_active, 1);
856 
857 	get_device(supplier);
858 	link->supplier = supplier;
859 	INIT_LIST_HEAD(&link->s_node);
860 	get_device(consumer);
861 	link->consumer = consumer;
862 	INIT_LIST_HEAD(&link->c_node);
863 	link->flags = flags;
864 	kref_init(&link->kref);
865 
866 	link->link_dev.class = &devlink_class;
867 	device_set_pm_not_required(&link->link_dev);
868 	dev_set_name(&link->link_dev, "%s:%s--%s:%s",
869 		     dev_bus_name(supplier), dev_name(supplier),
870 		     dev_bus_name(consumer), dev_name(consumer));
871 	if (device_register(&link->link_dev)) {
872 		put_device(&link->link_dev);
873 		link = NULL;
874 		goto out;
875 	}
876 
877 	if (flags & DL_FLAG_PM_RUNTIME) {
878 		if (flags & DL_FLAG_RPM_ACTIVE)
879 			refcount_inc(&link->rpm_active);
880 
881 		pm_runtime_new_link(consumer);
882 	}
883 
884 	/* Determine the initial link state. */
885 	if (flags & DL_FLAG_STATELESS)
886 		link->status = DL_STATE_NONE;
887 	else
888 		device_link_init_status(link, consumer, supplier);
889 
890 	/*
891 	 * Some callers expect the link creation during consumer driver probe to
892 	 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
893 	 */
894 	if (link->status == DL_STATE_CONSUMER_PROBE &&
895 	    flags & DL_FLAG_PM_RUNTIME)
896 		pm_runtime_resume(supplier);
897 
898 	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
899 	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
900 
901 	if (flags & DL_FLAG_SYNC_STATE_ONLY) {
902 		dev_dbg(consumer,
903 			"Linked as a sync state only consumer to %s\n",
904 			dev_name(supplier));
905 		goto out;
906 	}
907 
908 reorder:
909 	/*
910 	 * Move the consumer and all of the devices depending on it to the end
911 	 * of dpm_list and the devices_kset list.
912 	 *
913 	 * It is necessary to hold dpm_list locked throughout all that or else
914 	 * we may end up suspending with a wrong ordering of it.
915 	 */
916 	device_reorder_to_tail(consumer, NULL);
917 
918 	dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
919 
920 out:
921 	device_pm_unlock();
922 	device_links_write_unlock();
923 
924 	if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
925 		pm_runtime_put(supplier);
926 
927 	return link;
928 }
929 EXPORT_SYMBOL_GPL(device_link_add);
930 
931 static void __device_link_del(struct kref *kref)
932 {
933 	struct device_link *link = container_of(kref, struct device_link, kref);
934 
935 	dev_dbg(link->consumer, "Dropping the link to %s\n",
936 		dev_name(link->supplier));
937 
938 	pm_runtime_drop_link(link);
939 
940 	device_link_remove_from_lists(link);
941 	device_unregister(&link->link_dev);
942 }
943 
944 static void device_link_put_kref(struct device_link *link)
945 {
946 	if (link->flags & DL_FLAG_STATELESS)
947 		kref_put(&link->kref, __device_link_del);
948 	else if (!device_is_registered(link->consumer))
949 		__device_link_del(&link->kref);
950 	else
951 		WARN(1, "Unable to drop a managed device link reference\n");
952 }
953 
954 /**
955  * device_link_del - Delete a stateless link between two devices.
956  * @link: Device link to delete.
957  *
958  * The caller must ensure proper synchronization of this function with runtime
959  * PM.  If the link was added multiple times, it needs to be deleted as often.
960  * Care is required for hotplugged devices:  Their links are purged on removal
961  * and calling device_link_del() is then no longer allowed.
962  */
963 void device_link_del(struct device_link *link)
964 {
965 	device_links_write_lock();
966 	device_link_put_kref(link);
967 	device_links_write_unlock();
968 }
969 EXPORT_SYMBOL_GPL(device_link_del);
970 
971 /**
972  * device_link_remove - Delete a stateless link between two devices.
973  * @consumer: Consumer end of the link.
974  * @supplier: Supplier end of the link.
975  *
976  * The caller must ensure proper synchronization of this function with runtime
977  * PM.
978  */
979 void device_link_remove(void *consumer, struct device *supplier)
980 {
981 	struct device_link *link;
982 
983 	if (WARN_ON(consumer == supplier))
984 		return;
985 
986 	device_links_write_lock();
987 
988 	list_for_each_entry(link, &supplier->links.consumers, s_node) {
989 		if (link->consumer == consumer) {
990 			device_link_put_kref(link);
991 			break;
992 		}
993 	}
994 
995 	device_links_write_unlock();
996 }
997 EXPORT_SYMBOL_GPL(device_link_remove);
998 
999 static void device_links_missing_supplier(struct device *dev)
1000 {
1001 	struct device_link *link;
1002 
1003 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
1004 		if (link->status != DL_STATE_CONSUMER_PROBE)
1005 			continue;
1006 
1007 		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1008 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1009 		} else {
1010 			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
1011 			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1012 		}
1013 	}
1014 }
1015 
1016 static bool dev_is_best_effort(struct device *dev)
1017 {
1018 	return (fw_devlink_best_effort && dev->can_match) ||
1019 		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
1020 }
1021 
1022 static struct fwnode_handle *fwnode_links_check_suppliers(
1023 						struct fwnode_handle *fwnode)
1024 {
1025 	struct fwnode_link *link;
1026 
1027 	if (!fwnode || fw_devlink_is_permissive())
1028 		return NULL;
1029 
1030 	list_for_each_entry(link, &fwnode->suppliers, c_hook)
1031 		if (!(link->flags &
1032 		      (FWLINK_FLAG_CYCLE | FWLINK_FLAG_IGNORE)))
1033 			return link->supplier;
1034 
1035 	return NULL;
1036 }
1037 
1038 /**
1039  * device_links_check_suppliers - Check presence of supplier drivers.
1040  * @dev: Consumer device.
1041  *
1042  * Check links from this device to any suppliers.  Walk the list of the device's
1043  * links to suppliers and see if all of them are available.  If not, simply
1044  * return -EPROBE_DEFER.
1045  *
1046  * We need to guarantee that the supplier will not go away after the check has
1047  * been positive here.  It only can go away in __device_release_driver() and
1048  * that function  checks the device's links to consumers.  This means we need to
1049  * mark the link as "consumer probe in progress" to make the supplier removal
1050  * wait for us to complete (or bad things may happen).
1051  *
1052  * Links without the DL_FLAG_MANAGED flag set are ignored.
1053  */
1054 int device_links_check_suppliers(struct device *dev)
1055 {
1056 	struct device_link *link;
1057 	int ret = 0, fwnode_ret = 0;
1058 	struct fwnode_handle *sup_fw;
1059 
1060 	/*
1061 	 * Device waiting for supplier to become available is not allowed to
1062 	 * probe.
1063 	 */
1064 	mutex_lock(&fwnode_link_lock);
1065 	sup_fw = fwnode_links_check_suppliers(dev->fwnode);
1066 	if (sup_fw) {
1067 		if (!dev_is_best_effort(dev)) {
1068 			fwnode_ret = -EPROBE_DEFER;
1069 			dev_err_probe(dev, -EPROBE_DEFER,
1070 				    "wait for supplier %pfwf\n", sup_fw);
1071 		} else {
1072 			fwnode_ret = -EAGAIN;
1073 		}
1074 	}
1075 	mutex_unlock(&fwnode_link_lock);
1076 	if (fwnode_ret == -EPROBE_DEFER)
1077 		return fwnode_ret;
1078 
1079 	device_links_write_lock();
1080 
1081 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
1082 		if (!(link->flags & DL_FLAG_MANAGED))
1083 			continue;
1084 
1085 		if (link->status != DL_STATE_AVAILABLE &&
1086 		    !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
1087 
1088 			if (dev_is_best_effort(dev) &&
1089 			    link->flags & DL_FLAG_INFERRED &&
1090 			    !link->supplier->can_match) {
1091 				ret = -EAGAIN;
1092 				continue;
1093 			}
1094 
1095 			device_links_missing_supplier(dev);
1096 			dev_err_probe(dev, -EPROBE_DEFER,
1097 				      "supplier %s not ready\n",
1098 				      dev_name(link->supplier));
1099 			ret = -EPROBE_DEFER;
1100 			break;
1101 		}
1102 		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1103 	}
1104 	dev->links.status = DL_DEV_PROBING;
1105 
1106 	device_links_write_unlock();
1107 
1108 	return ret ? ret : fwnode_ret;
1109 }
1110 
1111 /**
1112  * __device_links_queue_sync_state - Queue a device for sync_state() callback
1113  * @dev: Device to call sync_state() on
1114  * @list: List head to queue the @dev on
1115  *
1116  * Queues a device for a sync_state() callback when the device links write lock
1117  * isn't held. This allows the sync_state() execution flow to use device links
1118  * APIs.  The caller must ensure this function is called with
1119  * device_links_write_lock() held.
1120  *
1121  * This function does a get_device() to make sure the device is not freed while
1122  * on this list.
1123  *
1124  * So the caller must also ensure that device_links_flush_sync_list() is called
1125  * as soon as the caller releases device_links_write_lock().  This is necessary
1126  * to make sure the sync_state() is called in a timely fashion and the
1127  * put_device() is called on this device.
1128  */
1129 static void __device_links_queue_sync_state(struct device *dev,
1130 					    struct list_head *list)
1131 {
1132 	struct device_link *link;
1133 
1134 	if (!dev_has_sync_state(dev))
1135 		return;
1136 	if (dev->state_synced)
1137 		return;
1138 
1139 	list_for_each_entry(link, &dev->links.consumers, s_node) {
1140 		if (!(link->flags & DL_FLAG_MANAGED))
1141 			continue;
1142 		if (link->status != DL_STATE_ACTIVE)
1143 			return;
1144 	}
1145 
1146 	/*
1147 	 * Set the flag here to avoid adding the same device to a list more
1148 	 * than once. This can happen if new consumers get added to the device
1149 	 * and probed before the list is flushed.
1150 	 */
1151 	dev->state_synced = true;
1152 
1153 	if (WARN_ON(!list_empty(&dev->links.defer_sync)))
1154 		return;
1155 
1156 	get_device(dev);
1157 	list_add_tail(&dev->links.defer_sync, list);
1158 }
1159 
1160 /**
1161  * device_links_flush_sync_list - Call sync_state() on a list of devices
1162  * @list: List of devices to call sync_state() on
1163  * @dont_lock_dev: Device for which lock is already held by the caller
1164  *
1165  * Calls sync_state() on all the devices that have been queued for it. This
1166  * function is used in conjunction with __device_links_queue_sync_state(). The
1167  * @dont_lock_dev parameter is useful when this function is called from a
1168  * context where a device lock is already held.
1169  */
1170 static void device_links_flush_sync_list(struct list_head *list,
1171 					 struct device *dont_lock_dev)
1172 {
1173 	struct device *dev, *tmp;
1174 
1175 	list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
1176 		list_del_init(&dev->links.defer_sync);
1177 
1178 		if (dev != dont_lock_dev)
1179 			device_lock(dev);
1180 
1181 		dev_sync_state(dev);
1182 
1183 		if (dev != dont_lock_dev)
1184 			device_unlock(dev);
1185 
1186 		put_device(dev);
1187 	}
1188 }
1189 
1190 void device_links_supplier_sync_state_pause(void)
1191 {
1192 	device_links_write_lock();
1193 	defer_sync_state_count++;
1194 	device_links_write_unlock();
1195 }
1196 
1197 void device_links_supplier_sync_state_resume(void)
1198 {
1199 	struct device *dev, *tmp;
1200 	LIST_HEAD(sync_list);
1201 
1202 	device_links_write_lock();
1203 	if (!defer_sync_state_count) {
1204 		WARN(true, "Unmatched sync_state pause/resume!");
1205 		goto out;
1206 	}
1207 	defer_sync_state_count--;
1208 	if (defer_sync_state_count)
1209 		goto out;
1210 
1211 	list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
1212 		/*
1213 		 * Delete from deferred_sync list before queuing it to
1214 		 * sync_list because defer_sync is used for both lists.
1215 		 */
1216 		list_del_init(&dev->links.defer_sync);
1217 		__device_links_queue_sync_state(dev, &sync_list);
1218 	}
1219 out:
1220 	device_links_write_unlock();
1221 
1222 	device_links_flush_sync_list(&sync_list, NULL);
1223 }
1224 
1225 static int sync_state_resume_initcall(void)
1226 {
1227 	device_links_supplier_sync_state_resume();
1228 	return 0;
1229 }
1230 late_initcall(sync_state_resume_initcall);
1231 
1232 static void __device_links_supplier_defer_sync(struct device *sup)
1233 {
1234 	if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup))
1235 		list_add_tail(&sup->links.defer_sync, &deferred_sync);
1236 }
1237 
1238 static void device_link_drop_managed(struct device_link *link)
1239 {
1240 	link->flags &= ~DL_FLAG_MANAGED;
1241 	WRITE_ONCE(link->status, DL_STATE_NONE);
1242 	kref_put(&link->kref, __device_link_del);
1243 }
1244 
1245 static ssize_t waiting_for_supplier_show(struct device *dev,
1246 					 struct device_attribute *attr,
1247 					 char *buf)
1248 {
1249 	bool val;
1250 
1251 	device_lock(dev);
1252 	mutex_lock(&fwnode_link_lock);
1253 	val = !!fwnode_links_check_suppliers(dev->fwnode);
1254 	mutex_unlock(&fwnode_link_lock);
1255 	device_unlock(dev);
1256 	return sysfs_emit(buf, "%u\n", val);
1257 }
1258 static DEVICE_ATTR_RO(waiting_for_supplier);
1259 
1260 /**
1261  * device_links_force_bind - Prepares device to be force bound
1262  * @dev: Consumer device.
1263  *
1264  * device_bind_driver() force binds a device to a driver without calling any
1265  * driver probe functions. So the consumer really isn't going to wait for any
1266  * supplier before it's bound to the driver. We still want the device link
1267  * states to be sensible when this happens.
1268  *
1269  * In preparation for device_bind_driver(), this function goes through each
1270  * supplier device links and checks if the supplier is bound. If it is, then
1271  * the device link status is set to CONSUMER_PROBE. Otherwise, the device link
1272  * is dropped. Links without the DL_FLAG_MANAGED flag set are ignored.
1273  */
1274 void device_links_force_bind(struct device *dev)
1275 {
1276 	struct device_link *link, *ln;
1277 
1278 	device_links_write_lock();
1279 
1280 	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1281 		if (!(link->flags & DL_FLAG_MANAGED))
1282 			continue;
1283 
1284 		if (link->status != DL_STATE_AVAILABLE) {
1285 			device_link_drop_managed(link);
1286 			continue;
1287 		}
1288 		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1289 	}
1290 	dev->links.status = DL_DEV_PROBING;
1291 
1292 	device_links_write_unlock();
1293 }
1294 
1295 /**
1296  * device_links_driver_bound - Update device links after probing its driver.
1297  * @dev: Device to update the links for.
1298  *
1299  * The probe has been successful, so update links from this device to any
1300  * consumers by changing their status to "available".
1301  *
1302  * Also change the status of @dev's links to suppliers to "active".
1303  *
1304  * Links without the DL_FLAG_MANAGED flag set are ignored.
1305  */
1306 void device_links_driver_bound(struct device *dev)
1307 {
1308 	struct device_link *link, *ln;
1309 	LIST_HEAD(sync_list);
1310 
1311 	/*
1312 	 * If a device binds successfully, it's expected to have created all
1313 	 * the device links it needs to or make new device links as it needs
1314 	 * them. So, fw_devlink no longer needs to create device links to any
1315 	 * of the device's suppliers.
1316 	 *
1317 	 * Also, if a child firmware node of this bound device is not added as a
1318 	 * device by now, assume it is never going to be added. Make this bound
1319 	 * device the fallback supplier to the dangling consumers of the child
1320 	 * firmware node because this bound device is probably implementing the
1321 	 * child firmware node functionality and we don't want the dangling
1322 	 * consumers to defer probe indefinitely waiting for a device for the
1323 	 * child firmware node.
1324 	 */
1325 	if (dev->fwnode && dev->fwnode->dev == dev) {
1326 		struct fwnode_handle *child;
1327 		fwnode_links_purge_suppliers(dev->fwnode);
1328 		mutex_lock(&fwnode_link_lock);
1329 		fwnode_for_each_available_child_node(dev->fwnode, child)
1330 			__fw_devlink_pickup_dangling_consumers(child,
1331 							       dev->fwnode);
1332 		__fw_devlink_link_to_consumers(dev);
1333 		mutex_unlock(&fwnode_link_lock);
1334 	}
1335 	device_remove_file(dev, &dev_attr_waiting_for_supplier);
1336 
1337 	device_links_write_lock();
1338 
1339 	list_for_each_entry(link, &dev->links.consumers, s_node) {
1340 		if (!(link->flags & DL_FLAG_MANAGED))
1341 			continue;
1342 
1343 		/*
1344 		 * Links created during consumer probe may be in the "consumer
1345 		 * probe" state to start with if the supplier is still probing
1346 		 * when they are created and they may become "active" if the
1347 		 * consumer probe returns first.  Skip them here.
1348 		 */
1349 		if (link->status == DL_STATE_CONSUMER_PROBE ||
1350 		    link->status == DL_STATE_ACTIVE)
1351 			continue;
1352 
1353 		WARN_ON(link->status != DL_STATE_DORMANT);
1354 		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1355 
1356 		if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)
1357 			driver_deferred_probe_add(link->consumer);
1358 	}
1359 
1360 	if (defer_sync_state_count)
1361 		__device_links_supplier_defer_sync(dev);
1362 	else
1363 		__device_links_queue_sync_state(dev, &sync_list);
1364 
1365 	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1366 		struct device *supplier;
1367 
1368 		if (!(link->flags & DL_FLAG_MANAGED))
1369 			continue;
1370 
1371 		supplier = link->supplier;
1372 		if (link->flags & DL_FLAG_SYNC_STATE_ONLY) {
1373 			/*
1374 			 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
1375 			 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
1376 			 * save to drop the managed link completely.
1377 			 */
1378 			device_link_drop_managed(link);
1379 		} else if (dev_is_best_effort(dev) &&
1380 			   link->flags & DL_FLAG_INFERRED &&
1381 			   link->status != DL_STATE_CONSUMER_PROBE &&
1382 			   !link->supplier->can_match) {
1383 			/*
1384 			 * When dev_is_best_effort() is true, we ignore device
1385 			 * links to suppliers that don't have a driver.  If the
1386 			 * consumer device still managed to probe, there's no
1387 			 * point in maintaining a device link in a weird state
1388 			 * (consumer probed before supplier). So delete it.
1389 			 */
1390 			device_link_drop_managed(link);
1391 		} else {
1392 			WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
1393 			WRITE_ONCE(link->status, DL_STATE_ACTIVE);
1394 		}
1395 
1396 		/*
1397 		 * This needs to be done even for the deleted
1398 		 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
1399 		 * device link that was preventing the supplier from getting a
1400 		 * sync_state() call.
1401 		 */
1402 		if (defer_sync_state_count)
1403 			__device_links_supplier_defer_sync(supplier);
1404 		else
1405 			__device_links_queue_sync_state(supplier, &sync_list);
1406 	}
1407 
1408 	dev->links.status = DL_DEV_DRIVER_BOUND;
1409 
1410 	device_links_write_unlock();
1411 
1412 	device_links_flush_sync_list(&sync_list, dev);
1413 }
1414 
1415 /**
1416  * __device_links_no_driver - Update links of a device without a driver.
1417  * @dev: Device without a drvier.
1418  *
1419  * Delete all non-persistent links from this device to any suppliers.
1420  *
1421  * Persistent links stay around, but their status is changed to "available",
1422  * unless they already are in the "supplier unbind in progress" state in which
1423  * case they need not be updated.
1424  *
1425  * Links without the DL_FLAG_MANAGED flag set are ignored.
1426  */
1427 static void __device_links_no_driver(struct device *dev)
1428 {
1429 	struct device_link *link, *ln;
1430 
1431 	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1432 		if (!(link->flags & DL_FLAG_MANAGED))
1433 			continue;
1434 
1435 		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
1436 			device_link_drop_managed(link);
1437 			continue;
1438 		}
1439 
1440 		if (link->status != DL_STATE_CONSUMER_PROBE &&
1441 		    link->status != DL_STATE_ACTIVE)
1442 			continue;
1443 
1444 		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1445 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1446 		} else {
1447 			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
1448 			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1449 		}
1450 	}
1451 
1452 	dev->links.status = DL_DEV_NO_DRIVER;
1453 }
1454 
1455 /**
1456  * device_links_no_driver - Update links after failing driver probe.
1457  * @dev: Device whose driver has just failed to probe.
1458  *
1459  * Clean up leftover links to consumers for @dev and invoke
1460  * %__device_links_no_driver() to update links to suppliers for it as
1461  * appropriate.
1462  *
1463  * Links without the DL_FLAG_MANAGED flag set are ignored.
1464  */
1465 void device_links_no_driver(struct device *dev)
1466 {
1467 	struct device_link *link;
1468 
1469 	device_links_write_lock();
1470 
1471 	list_for_each_entry(link, &dev->links.consumers, s_node) {
1472 		if (!(link->flags & DL_FLAG_MANAGED))
1473 			continue;
1474 
1475 		/*
1476 		 * The probe has failed, so if the status of the link is
1477 		 * "consumer probe" or "active", it must have been added by
1478 		 * a probing consumer while this device was still probing.
1479 		 * Change its state to "dormant", as it represents a valid
1480 		 * relationship, but it is not functionally meaningful.
1481 		 */
1482 		if (link->status == DL_STATE_CONSUMER_PROBE ||
1483 		    link->status == DL_STATE_ACTIVE)
1484 			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1485 	}
1486 
1487 	__device_links_no_driver(dev);
1488 
1489 	device_links_write_unlock();
1490 }
1491 
1492 /**
1493  * device_links_driver_cleanup - Update links after driver removal.
1494  * @dev: Device whose driver has just gone away.
1495  *
1496  * Update links to consumers for @dev by changing their status to "dormant" and
1497  * invoke %__device_links_no_driver() to update links to suppliers for it as
1498  * appropriate.
1499  *
1500  * Links without the DL_FLAG_MANAGED flag set are ignored.
1501  */
1502 void device_links_driver_cleanup(struct device *dev)
1503 {
1504 	struct device_link *link, *ln;
1505 
1506 	device_links_write_lock();
1507 
1508 	list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
1509 		if (!(link->flags & DL_FLAG_MANAGED))
1510 			continue;
1511 
1512 		WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
1513 		WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
1514 
1515 		/*
1516 		 * autoremove the links between this @dev and its consumer
1517 		 * devices that are not active, i.e. where the link state
1518 		 * has moved to DL_STATE_SUPPLIER_UNBIND.
1519 		 */
1520 		if (link->status == DL_STATE_SUPPLIER_UNBIND &&
1521 		    link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
1522 			device_link_drop_managed(link);
1523 
1524 		WRITE_ONCE(link->status, DL_STATE_DORMANT);
1525 	}
1526 
1527 	list_del_init(&dev->links.defer_sync);
1528 	__device_links_no_driver(dev);
1529 
1530 	device_links_write_unlock();
1531 }
1532 
1533 /**
1534  * device_links_busy - Check if there are any busy links to consumers.
1535  * @dev: Device to check.
1536  *
1537  * Check each consumer of the device and return 'true' if its link's status
1538  * is one of "consumer probe" or "active" (meaning that the given consumer is
1539  * probing right now or its driver is present).  Otherwise, change the link
1540  * state to "supplier unbind" to prevent the consumer from being probed
1541  * successfully going forward.
1542  *
1543  * Return 'false' if there are no probing or active consumers.
1544  *
1545  * Links without the DL_FLAG_MANAGED flag set are ignored.
1546  */
1547 bool device_links_busy(struct device *dev)
1548 {
1549 	struct device_link *link;
1550 	bool ret = false;
1551 
1552 	device_links_write_lock();
1553 
1554 	list_for_each_entry(link, &dev->links.consumers, s_node) {
1555 		if (!(link->flags & DL_FLAG_MANAGED))
1556 			continue;
1557 
1558 		if (link->status == DL_STATE_CONSUMER_PROBE
1559 		    || link->status == DL_STATE_ACTIVE) {
1560 			ret = true;
1561 			break;
1562 		}
1563 		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1564 	}
1565 
1566 	dev->links.status = DL_DEV_UNBINDING;
1567 
1568 	device_links_write_unlock();
1569 	return ret;
1570 }
1571 
1572 /**
1573  * device_links_unbind_consumers - Force unbind consumers of the given device.
1574  * @dev: Device to unbind the consumers of.
1575  *
1576  * Walk the list of links to consumers for @dev and if any of them is in the
1577  * "consumer probe" state, wait for all device probes in progress to complete
1578  * and start over.
1579  *
1580  * If that's not the case, change the status of the link to "supplier unbind"
1581  * and check if the link was in the "active" state.  If so, force the consumer
1582  * driver to unbind and start over (the consumer will not re-probe as we have
1583  * changed the state of the link already).
1584  *
1585  * Links without the DL_FLAG_MANAGED flag set are ignored.
1586  */
1587 void device_links_unbind_consumers(struct device *dev)
1588 {
1589 	struct device_link *link;
1590 
1591  start:
1592 	device_links_write_lock();
1593 
1594 	list_for_each_entry(link, &dev->links.consumers, s_node) {
1595 		enum device_link_state status;
1596 
1597 		if (!(link->flags & DL_FLAG_MANAGED) ||
1598 		    link->flags & DL_FLAG_SYNC_STATE_ONLY)
1599 			continue;
1600 
1601 		status = link->status;
1602 		if (status == DL_STATE_CONSUMER_PROBE) {
1603 			device_links_write_unlock();
1604 
1605 			wait_for_device_probe();
1606 			goto start;
1607 		}
1608 		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1609 		if (status == DL_STATE_ACTIVE) {
1610 			struct device *consumer = link->consumer;
1611 
1612 			get_device(consumer);
1613 
1614 			device_links_write_unlock();
1615 
1616 			device_release_driver_internal(consumer, NULL,
1617 						       consumer->parent);
1618 			put_device(consumer);
1619 			goto start;
1620 		}
1621 	}
1622 
1623 	device_links_write_unlock();
1624 }
1625 
1626 /**
1627  * device_links_purge - Delete existing links to other devices.
1628  * @dev: Target device.
1629  */
1630 static void device_links_purge(struct device *dev)
1631 {
1632 	struct device_link *link, *ln;
1633 
1634 	if (dev->class == &devlink_class)
1635 		return;
1636 
1637 	/*
1638 	 * Delete all of the remaining links from this device to any other
1639 	 * devices (either consumers or suppliers).
1640 	 */
1641 	device_links_write_lock();
1642 
1643 	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1644 		WARN_ON(link->status == DL_STATE_ACTIVE);
1645 		__device_link_del(&link->kref);
1646 	}
1647 
1648 	list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
1649 		WARN_ON(link->status != DL_STATE_DORMANT &&
1650 			link->status != DL_STATE_NONE);
1651 		__device_link_del(&link->kref);
1652 	}
1653 
1654 	device_links_write_unlock();
1655 }
1656 
1657 #define FW_DEVLINK_FLAGS_PERMISSIVE	(DL_FLAG_INFERRED | \
1658 					 DL_FLAG_SYNC_STATE_ONLY)
1659 #define FW_DEVLINK_FLAGS_ON		(DL_FLAG_INFERRED | \
1660 					 DL_FLAG_AUTOPROBE_CONSUMER)
1661 #define FW_DEVLINK_FLAGS_RPM		(FW_DEVLINK_FLAGS_ON | \
1662 					 DL_FLAG_PM_RUNTIME)
1663 
1664 static u32 fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1665 static int __init fw_devlink_setup(char *arg)
1666 {
1667 	if (!arg)
1668 		return -EINVAL;
1669 
1670 	if (strcmp(arg, "off") == 0) {
1671 		fw_devlink_flags = 0;
1672 	} else if (strcmp(arg, "permissive") == 0) {
1673 		fw_devlink_flags = FW_DEVLINK_FLAGS_PERMISSIVE;
1674 	} else if (strcmp(arg, "on") == 0) {
1675 		fw_devlink_flags = FW_DEVLINK_FLAGS_ON;
1676 	} else if (strcmp(arg, "rpm") == 0) {
1677 		fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1678 	}
1679 	return 0;
1680 }
1681 early_param("fw_devlink", fw_devlink_setup);
1682 
1683 static bool fw_devlink_strict;
1684 static int __init fw_devlink_strict_setup(char *arg)
1685 {
1686 	return kstrtobool(arg, &fw_devlink_strict);
1687 }
1688 early_param("fw_devlink.strict", fw_devlink_strict_setup);
1689 
1690 #define FW_DEVLINK_SYNC_STATE_STRICT	0
1691 #define FW_DEVLINK_SYNC_STATE_TIMEOUT	1
1692 
1693 #ifndef CONFIG_FW_DEVLINK_SYNC_STATE_TIMEOUT
1694 static int fw_devlink_sync_state;
1695 #else
1696 static int fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1697 #endif
1698 
1699 static int __init fw_devlink_sync_state_setup(char *arg)
1700 {
1701 	if (!arg)
1702 		return -EINVAL;
1703 
1704 	if (strcmp(arg, "strict") == 0) {
1705 		fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_STRICT;
1706 		return 0;
1707 	} else if (strcmp(arg, "timeout") == 0) {
1708 		fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1709 		return 0;
1710 	}
1711 	return -EINVAL;
1712 }
1713 early_param("fw_devlink.sync_state", fw_devlink_sync_state_setup);
1714 
1715 static inline u32 fw_devlink_get_flags(u8 fwlink_flags)
1716 {
1717 	if (fwlink_flags & FWLINK_FLAG_CYCLE)
1718 		return FW_DEVLINK_FLAGS_PERMISSIVE | DL_FLAG_CYCLE;
1719 
1720 	return fw_devlink_flags;
1721 }
1722 
1723 static bool fw_devlink_is_permissive(void)
1724 {
1725 	return fw_devlink_flags == FW_DEVLINK_FLAGS_PERMISSIVE;
1726 }
1727 
1728 bool fw_devlink_is_strict(void)
1729 {
1730 	return fw_devlink_strict && !fw_devlink_is_permissive();
1731 }
1732 
1733 static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
1734 {
1735 	if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
1736 		return;
1737 
1738 	fwnode_call_int_op(fwnode, add_links);
1739 	fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
1740 }
1741 
1742 static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
1743 {
1744 	struct fwnode_handle *child = NULL;
1745 
1746 	fw_devlink_parse_fwnode(fwnode);
1747 
1748 	while ((child = fwnode_get_next_available_child_node(fwnode, child)))
1749 		fw_devlink_parse_fwtree(child);
1750 }
1751 
1752 static void fw_devlink_relax_link(struct device_link *link)
1753 {
1754 	if (!(link->flags & DL_FLAG_INFERRED))
1755 		return;
1756 
1757 	if (device_link_flag_is_sync_state_only(link->flags))
1758 		return;
1759 
1760 	pm_runtime_drop_link(link);
1761 	link->flags = DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE;
1762 	dev_dbg(link->consumer, "Relaxing link with %s\n",
1763 		dev_name(link->supplier));
1764 }
1765 
1766 static int fw_devlink_no_driver(struct device *dev, void *data)
1767 {
1768 	struct device_link *link = to_devlink(dev);
1769 
1770 	if (!link->supplier->can_match)
1771 		fw_devlink_relax_link(link);
1772 
1773 	return 0;
1774 }
1775 
1776 void fw_devlink_drivers_done(void)
1777 {
1778 	fw_devlink_drv_reg_done = true;
1779 	device_links_write_lock();
1780 	class_for_each_device(&devlink_class, NULL, NULL,
1781 			      fw_devlink_no_driver);
1782 	device_links_write_unlock();
1783 }
1784 
1785 static int fw_devlink_dev_sync_state(struct device *dev, void *data)
1786 {
1787 	struct device_link *link = to_devlink(dev);
1788 	struct device *sup = link->supplier;
1789 
1790 	if (!(link->flags & DL_FLAG_MANAGED) ||
1791 	    link->status == DL_STATE_ACTIVE || sup->state_synced ||
1792 	    !dev_has_sync_state(sup))
1793 		return 0;
1794 
1795 	if (fw_devlink_sync_state == FW_DEVLINK_SYNC_STATE_STRICT) {
1796 		dev_warn(sup, "sync_state() pending due to %s\n",
1797 			 dev_name(link->consumer));
1798 		return 0;
1799 	}
1800 
1801 	if (!list_empty(&sup->links.defer_sync))
1802 		return 0;
1803 
1804 	dev_warn(sup, "Timed out. Forcing sync_state()\n");
1805 	sup->state_synced = true;
1806 	get_device(sup);
1807 	list_add_tail(&sup->links.defer_sync, data);
1808 
1809 	return 0;
1810 }
1811 
1812 void fw_devlink_probing_done(void)
1813 {
1814 	LIST_HEAD(sync_list);
1815 
1816 	device_links_write_lock();
1817 	class_for_each_device(&devlink_class, NULL, &sync_list,
1818 			      fw_devlink_dev_sync_state);
1819 	device_links_write_unlock();
1820 	device_links_flush_sync_list(&sync_list, NULL);
1821 }
1822 
1823 /**
1824  * wait_for_init_devices_probe - Try to probe any device needed for init
1825  *
1826  * Some devices might need to be probed and bound successfully before the kernel
1827  * boot sequence can finish and move on to init/userspace. For example, a
1828  * network interface might need to be bound to be able to mount a NFS rootfs.
1829  *
1830  * With fw_devlink=on by default, some of these devices might be blocked from
1831  * probing because they are waiting on a optional supplier that doesn't have a
1832  * driver. While fw_devlink will eventually identify such devices and unblock
1833  * the probing automatically, it might be too late by the time it unblocks the
1834  * probing of devices. For example, the IP4 autoconfig might timeout before
1835  * fw_devlink unblocks probing of the network interface.
1836  *
1837  * This function is available to temporarily try and probe all devices that have
1838  * a driver even if some of their suppliers haven't been added or don't have
1839  * drivers.
1840  *
1841  * The drivers can then decide which of the suppliers are optional vs mandatory
1842  * and probe the device if possible. By the time this function returns, all such
1843  * "best effort" probes are guaranteed to be completed. If a device successfully
1844  * probes in this mode, we delete all fw_devlink discovered dependencies of that
1845  * device where the supplier hasn't yet probed successfully because they have to
1846  * be optional dependencies.
1847  *
1848  * Any devices that didn't successfully probe go back to being treated as if
1849  * this function was never called.
1850  *
1851  * This also means that some devices that aren't needed for init and could have
1852  * waited for their optional supplier to probe (when the supplier's module is
1853  * loaded later on) would end up probing prematurely with limited functionality.
1854  * So call this function only when boot would fail without it.
1855  */
1856 void __init wait_for_init_devices_probe(void)
1857 {
1858 	if (!fw_devlink_flags || fw_devlink_is_permissive())
1859 		return;
1860 
1861 	/*
1862 	 * Wait for all ongoing probes to finish so that the "best effort" is
1863 	 * only applied to devices that can't probe otherwise.
1864 	 */
1865 	wait_for_device_probe();
1866 
1867 	pr_info("Trying to probe devices needed for running init ...\n");
1868 	fw_devlink_best_effort = true;
1869 	driver_deferred_probe_trigger();
1870 
1871 	/*
1872 	 * Wait for all "best effort" probes to finish before going back to
1873 	 * normal enforcement.
1874 	 */
1875 	wait_for_device_probe();
1876 	fw_devlink_best_effort = false;
1877 }
1878 
1879 static void fw_devlink_unblock_consumers(struct device *dev)
1880 {
1881 	struct device_link *link;
1882 
1883 	if (!fw_devlink_flags || fw_devlink_is_permissive())
1884 		return;
1885 
1886 	device_links_write_lock();
1887 	list_for_each_entry(link, &dev->links.consumers, s_node)
1888 		fw_devlink_relax_link(link);
1889 	device_links_write_unlock();
1890 }
1891 
1892 #define get_dev_from_fwnode(fwnode)	get_device((fwnode)->dev)
1893 
1894 static bool fwnode_init_without_drv(struct fwnode_handle *fwnode)
1895 {
1896 	struct device *dev;
1897 	bool ret;
1898 
1899 	if (!(fwnode->flags & FWNODE_FLAG_INITIALIZED))
1900 		return false;
1901 
1902 	dev = get_dev_from_fwnode(fwnode);
1903 	ret = !dev || dev->links.status == DL_DEV_NO_DRIVER;
1904 	put_device(dev);
1905 
1906 	return ret;
1907 }
1908 
1909 static bool fwnode_ancestor_init_without_drv(struct fwnode_handle *fwnode)
1910 {
1911 	struct fwnode_handle *parent;
1912 
1913 	fwnode_for_each_parent_node(fwnode, parent) {
1914 		if (fwnode_init_without_drv(parent)) {
1915 			fwnode_handle_put(parent);
1916 			return true;
1917 		}
1918 	}
1919 
1920 	return false;
1921 }
1922 
1923 /**
1924  * fwnode_is_ancestor_of - Test if @ancestor is ancestor of @child
1925  * @ancestor: Firmware which is tested for being an ancestor
1926  * @child: Firmware which is tested for being the child
1927  *
1928  * A node is considered an ancestor of itself too.
1929  *
1930  * Return: true if @ancestor is an ancestor of @child. Otherwise, returns false.
1931  */
1932 static bool fwnode_is_ancestor_of(const struct fwnode_handle *ancestor,
1933 				  const struct fwnode_handle *child)
1934 {
1935 	struct fwnode_handle *parent;
1936 
1937 	if (IS_ERR_OR_NULL(ancestor))
1938 		return false;
1939 
1940 	if (child == ancestor)
1941 		return true;
1942 
1943 	fwnode_for_each_parent_node(child, parent) {
1944 		if (parent == ancestor) {
1945 			fwnode_handle_put(parent);
1946 			return true;
1947 		}
1948 	}
1949 	return false;
1950 }
1951 
1952 /**
1953  * fwnode_get_next_parent_dev - Find device of closest ancestor fwnode
1954  * @fwnode: firmware node
1955  *
1956  * Given a firmware node (@fwnode), this function finds its closest ancestor
1957  * firmware node that has a corresponding struct device and returns that struct
1958  * device.
1959  *
1960  * The caller is responsible for calling put_device() on the returned device
1961  * pointer.
1962  *
1963  * Return: a pointer to the device of the @fwnode's closest ancestor.
1964  */
1965 static struct device *fwnode_get_next_parent_dev(const struct fwnode_handle *fwnode)
1966 {
1967 	struct fwnode_handle *parent;
1968 	struct device *dev;
1969 
1970 	fwnode_for_each_parent_node(fwnode, parent) {
1971 		dev = get_dev_from_fwnode(parent);
1972 		if (dev) {
1973 			fwnode_handle_put(parent);
1974 			return dev;
1975 		}
1976 	}
1977 	return NULL;
1978 }
1979 
1980 /**
1981  * __fw_devlink_relax_cycles - Relax and mark dependency cycles.
1982  * @con: Potential consumer device.
1983  * @sup_handle: Potential supplier's fwnode.
1984  *
1985  * Needs to be called with fwnode_lock and device link lock held.
1986  *
1987  * Check if @sup_handle or any of its ancestors or suppliers direct/indirectly
1988  * depend on @con. This function can detect multiple cyles between @sup_handle
1989  * and @con. When such dependency cycles are found, convert all device links
1990  * created solely by fw_devlink into SYNC_STATE_ONLY device links. Also, mark
1991  * all fwnode links in the cycle with FWLINK_FLAG_CYCLE so that when they are
1992  * converted into a device link in the future, they are created as
1993  * SYNC_STATE_ONLY device links. This is the equivalent of doing
1994  * fw_devlink=permissive just between the devices in the cycle. We need to do
1995  * this because, at this point, fw_devlink can't tell which of these
1996  * dependencies is not a real dependency.
1997  *
1998  * Return true if one or more cycles were found. Otherwise, return false.
1999  */
2000 static bool __fw_devlink_relax_cycles(struct device *con,
2001 				 struct fwnode_handle *sup_handle)
2002 {
2003 	struct device *sup_dev = NULL, *par_dev = NULL;
2004 	struct fwnode_link *link;
2005 	struct device_link *dev_link;
2006 	bool ret = false;
2007 
2008 	if (!sup_handle)
2009 		return false;
2010 
2011 	/*
2012 	 * We aren't trying to find all cycles. Just a cycle between con and
2013 	 * sup_handle.
2014 	 */
2015 	if (sup_handle->flags & FWNODE_FLAG_VISITED)
2016 		return false;
2017 
2018 	sup_handle->flags |= FWNODE_FLAG_VISITED;
2019 
2020 	sup_dev = get_dev_from_fwnode(sup_handle);
2021 
2022 	/* Termination condition. */
2023 	if (sup_dev == con) {
2024 		pr_debug("----- cycle: start -----\n");
2025 		ret = true;
2026 		goto out;
2027 	}
2028 
2029 	/*
2030 	 * If sup_dev is bound to a driver and @con hasn't started binding to a
2031 	 * driver, sup_dev can't be a consumer of @con. So, no need to check
2032 	 * further.
2033 	 */
2034 	if (sup_dev && sup_dev->links.status ==  DL_DEV_DRIVER_BOUND &&
2035 	    con->links.status == DL_DEV_NO_DRIVER) {
2036 		ret = false;
2037 		goto out;
2038 	}
2039 
2040 	list_for_each_entry(link, &sup_handle->suppliers, c_hook) {
2041 		if (link->flags & FWLINK_FLAG_IGNORE)
2042 			continue;
2043 
2044 		if (__fw_devlink_relax_cycles(con, link->supplier)) {
2045 			__fwnode_link_cycle(link);
2046 			ret = true;
2047 		}
2048 	}
2049 
2050 	/*
2051 	 * Give priority to device parent over fwnode parent to account for any
2052 	 * quirks in how fwnodes are converted to devices.
2053 	 */
2054 	if (sup_dev)
2055 		par_dev = get_device(sup_dev->parent);
2056 	else
2057 		par_dev = fwnode_get_next_parent_dev(sup_handle);
2058 
2059 	if (par_dev && __fw_devlink_relax_cycles(con, par_dev->fwnode)) {
2060 		pr_debug("%pfwf: cycle: child of %pfwf\n", sup_handle,
2061 			 par_dev->fwnode);
2062 		ret = true;
2063 	}
2064 
2065 	if (!sup_dev)
2066 		goto out;
2067 
2068 	list_for_each_entry(dev_link, &sup_dev->links.suppliers, c_node) {
2069 		/*
2070 		 * Ignore a SYNC_STATE_ONLY flag only if it wasn't marked as
2071 		 * such due to a cycle.
2072 		 */
2073 		if (device_link_flag_is_sync_state_only(dev_link->flags) &&
2074 		    !(dev_link->flags & DL_FLAG_CYCLE))
2075 			continue;
2076 
2077 		if (__fw_devlink_relax_cycles(con,
2078 					      dev_link->supplier->fwnode)) {
2079 			pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
2080 				 dev_link->supplier->fwnode);
2081 			fw_devlink_relax_link(dev_link);
2082 			dev_link->flags |= DL_FLAG_CYCLE;
2083 			ret = true;
2084 		}
2085 	}
2086 
2087 out:
2088 	sup_handle->flags &= ~FWNODE_FLAG_VISITED;
2089 	put_device(sup_dev);
2090 	put_device(par_dev);
2091 	return ret;
2092 }
2093 
2094 /**
2095  * fw_devlink_create_devlink - Create a device link from a consumer to fwnode
2096  * @con: consumer device for the device link
2097  * @sup_handle: fwnode handle of supplier
2098  * @link: fwnode link that's being converted to a device link
2099  *
2100  * This function will try to create a device link between the consumer device
2101  * @con and the supplier device represented by @sup_handle.
2102  *
2103  * The supplier has to be provided as a fwnode because incorrect cycles in
2104  * fwnode links can sometimes cause the supplier device to never be created.
2105  * This function detects such cases and returns an error if it cannot create a
2106  * device link from the consumer to a missing supplier.
2107  *
2108  * Returns,
2109  * 0 on successfully creating a device link
2110  * -EINVAL if the device link cannot be created as expected
2111  * -EAGAIN if the device link cannot be created right now, but it may be
2112  *  possible to do that in the future
2113  */
2114 static int fw_devlink_create_devlink(struct device *con,
2115 				     struct fwnode_handle *sup_handle,
2116 				     struct fwnode_link *link)
2117 {
2118 	struct device *sup_dev;
2119 	int ret = 0;
2120 	u32 flags;
2121 
2122 	if (link->flags & FWLINK_FLAG_IGNORE)
2123 		return 0;
2124 
2125 	if (con->fwnode == link->consumer)
2126 		flags = fw_devlink_get_flags(link->flags);
2127 	else
2128 		flags = FW_DEVLINK_FLAGS_PERMISSIVE;
2129 
2130 	/*
2131 	 * In some cases, a device P might also be a supplier to its child node
2132 	 * C. However, this would defer the probe of C until the probe of P
2133 	 * completes successfully. This is perfectly fine in the device driver
2134 	 * model. device_add() doesn't guarantee probe completion of the device
2135 	 * by the time it returns.
2136 	 *
2137 	 * However, there are a few drivers that assume C will finish probing
2138 	 * as soon as it's added and before P finishes probing. So, we provide
2139 	 * a flag to let fw_devlink know not to delay the probe of C until the
2140 	 * probe of P completes successfully.
2141 	 *
2142 	 * When such a flag is set, we can't create device links where P is the
2143 	 * supplier of C as that would delay the probe of C.
2144 	 */
2145 	if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
2146 	    fwnode_is_ancestor_of(sup_handle, con->fwnode))
2147 		return -EINVAL;
2148 
2149 	/*
2150 	 * SYNC_STATE_ONLY device links don't block probing and supports cycles.
2151 	 * So, one might expect that cycle detection isn't necessary for them.
2152 	 * However, if the device link was marked as SYNC_STATE_ONLY because
2153 	 * it's part of a cycle, then we still need to do cycle detection. This
2154 	 * is because the consumer and supplier might be part of multiple cycles
2155 	 * and we need to detect all those cycles.
2156 	 */
2157 	if (!device_link_flag_is_sync_state_only(flags) ||
2158 	    flags & DL_FLAG_CYCLE) {
2159 		device_links_write_lock();
2160 		if (__fw_devlink_relax_cycles(con, sup_handle)) {
2161 			__fwnode_link_cycle(link);
2162 			flags = fw_devlink_get_flags(link->flags);
2163 			pr_debug("----- cycle: end -----\n");
2164 			dev_info(con, "Fixed dependency cycle(s) with %pfwf\n",
2165 				 sup_handle);
2166 		}
2167 		device_links_write_unlock();
2168 	}
2169 
2170 	if (sup_handle->flags & FWNODE_FLAG_NOT_DEVICE)
2171 		sup_dev = fwnode_get_next_parent_dev(sup_handle);
2172 	else
2173 		sup_dev = get_dev_from_fwnode(sup_handle);
2174 
2175 	if (sup_dev) {
2176 		/*
2177 		 * If it's one of those drivers that don't actually bind to
2178 		 * their device using driver core, then don't wait on this
2179 		 * supplier device indefinitely.
2180 		 */
2181 		if (sup_dev->links.status == DL_DEV_NO_DRIVER &&
2182 		    sup_handle->flags & FWNODE_FLAG_INITIALIZED) {
2183 			dev_dbg(con,
2184 				"Not linking %pfwf - dev might never probe\n",
2185 				sup_handle);
2186 			ret = -EINVAL;
2187 			goto out;
2188 		}
2189 
2190 		if (con != sup_dev && !device_link_add(con, sup_dev, flags)) {
2191 			dev_err(con, "Failed to create device link (0x%x) with %s\n",
2192 				flags, dev_name(sup_dev));
2193 			ret = -EINVAL;
2194 		}
2195 
2196 		goto out;
2197 	}
2198 
2199 	/*
2200 	 * Supplier or supplier's ancestor already initialized without a struct
2201 	 * device or being probed by a driver.
2202 	 */
2203 	if (fwnode_init_without_drv(sup_handle) ||
2204 	    fwnode_ancestor_init_without_drv(sup_handle)) {
2205 		dev_dbg(con, "Not linking %pfwf - might never become dev\n",
2206 			sup_handle);
2207 		return -EINVAL;
2208 	}
2209 
2210 	ret = -EAGAIN;
2211 out:
2212 	put_device(sup_dev);
2213 	return ret;
2214 }
2215 
2216 /**
2217  * __fw_devlink_link_to_consumers - Create device links to consumers of a device
2218  * @dev: Device that needs to be linked to its consumers
2219  *
2220  * This function looks at all the consumer fwnodes of @dev and creates device
2221  * links between the consumer device and @dev (supplier).
2222  *
2223  * If the consumer device has not been added yet, then this function creates a
2224  * SYNC_STATE_ONLY link between @dev (supplier) and the closest ancestor device
2225  * of the consumer fwnode. This is necessary to make sure @dev doesn't get a
2226  * sync_state() callback before the real consumer device gets to be added and
2227  * then probed.
2228  *
2229  * Once device links are created from the real consumer to @dev (supplier), the
2230  * fwnode links are deleted.
2231  */
2232 static void __fw_devlink_link_to_consumers(struct device *dev)
2233 {
2234 	struct fwnode_handle *fwnode = dev->fwnode;
2235 	struct fwnode_link *link, *tmp;
2236 
2237 	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) {
2238 		struct device *con_dev;
2239 		bool own_link = true;
2240 		int ret;
2241 
2242 		con_dev = get_dev_from_fwnode(link->consumer);
2243 		/*
2244 		 * If consumer device is not available yet, make a "proxy"
2245 		 * SYNC_STATE_ONLY link from the consumer's parent device to
2246 		 * the supplier device. This is necessary to make sure the
2247 		 * supplier doesn't get a sync_state() callback before the real
2248 		 * consumer can create a device link to the supplier.
2249 		 *
2250 		 * This proxy link step is needed to handle the case where the
2251 		 * consumer's parent device is added before the supplier.
2252 		 */
2253 		if (!con_dev) {
2254 			con_dev = fwnode_get_next_parent_dev(link->consumer);
2255 			/*
2256 			 * However, if the consumer's parent device is also the
2257 			 * parent of the supplier, don't create a
2258 			 * consumer-supplier link from the parent to its child
2259 			 * device. Such a dependency is impossible.
2260 			 */
2261 			if (con_dev &&
2262 			    fwnode_is_ancestor_of(con_dev->fwnode, fwnode)) {
2263 				put_device(con_dev);
2264 				con_dev = NULL;
2265 			} else {
2266 				own_link = false;
2267 			}
2268 		}
2269 
2270 		if (!con_dev)
2271 			continue;
2272 
2273 		ret = fw_devlink_create_devlink(con_dev, fwnode, link);
2274 		put_device(con_dev);
2275 		if (!own_link || ret == -EAGAIN)
2276 			continue;
2277 
2278 		__fwnode_link_del(link);
2279 	}
2280 }
2281 
2282 /**
2283  * __fw_devlink_link_to_suppliers - Create device links to suppliers of a device
2284  * @dev: The consumer device that needs to be linked to its suppliers
2285  * @fwnode: Root of the fwnode tree that is used to create device links
2286  *
2287  * This function looks at all the supplier fwnodes of fwnode tree rooted at
2288  * @fwnode and creates device links between @dev (consumer) and all the
2289  * supplier devices of the entire fwnode tree at @fwnode.
2290  *
2291  * The function creates normal (non-SYNC_STATE_ONLY) device links between @dev
2292  * and the real suppliers of @dev. Once these device links are created, the
2293  * fwnode links are deleted.
2294  *
2295  * In addition, it also looks at all the suppliers of the entire fwnode tree
2296  * because some of the child devices of @dev that have not been added yet
2297  * (because @dev hasn't probed) might already have their suppliers added to
2298  * driver core. So, this function creates SYNC_STATE_ONLY device links between
2299  * @dev (consumer) and these suppliers to make sure they don't execute their
2300  * sync_state() callbacks before these child devices have a chance to create
2301  * their device links. The fwnode links that correspond to the child devices
2302  * aren't delete because they are needed later to create the device links
2303  * between the real consumer and supplier devices.
2304  */
2305 static void __fw_devlink_link_to_suppliers(struct device *dev,
2306 					   struct fwnode_handle *fwnode)
2307 {
2308 	bool own_link = (dev->fwnode == fwnode);
2309 	struct fwnode_link *link, *tmp;
2310 	struct fwnode_handle *child = NULL;
2311 
2312 	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) {
2313 		int ret;
2314 		struct fwnode_handle *sup = link->supplier;
2315 
2316 		ret = fw_devlink_create_devlink(dev, sup, link);
2317 		if (!own_link || ret == -EAGAIN)
2318 			continue;
2319 
2320 		__fwnode_link_del(link);
2321 	}
2322 
2323 	/*
2324 	 * Make "proxy" SYNC_STATE_ONLY device links to represent the needs of
2325 	 * all the descendants. This proxy link step is needed to handle the
2326 	 * case where the supplier is added before the consumer's parent device
2327 	 * (@dev).
2328 	 */
2329 	while ((child = fwnode_get_next_available_child_node(fwnode, child)))
2330 		__fw_devlink_link_to_suppliers(dev, child);
2331 }
2332 
2333 static void fw_devlink_link_device(struct device *dev)
2334 {
2335 	struct fwnode_handle *fwnode = dev->fwnode;
2336 
2337 	if (!fw_devlink_flags)
2338 		return;
2339 
2340 	fw_devlink_parse_fwtree(fwnode);
2341 
2342 	mutex_lock(&fwnode_link_lock);
2343 	__fw_devlink_link_to_consumers(dev);
2344 	__fw_devlink_link_to_suppliers(dev, fwnode);
2345 	mutex_unlock(&fwnode_link_lock);
2346 }
2347 
2348 /* Device links support end. */
2349 
2350 static struct kobject *dev_kobj;
2351 
2352 /* /sys/dev/char */
2353 static struct kobject *sysfs_dev_char_kobj;
2354 
2355 /* /sys/dev/block */
2356 static struct kobject *sysfs_dev_block_kobj;
2357 
2358 static DEFINE_MUTEX(device_hotplug_lock);
2359 
2360 void lock_device_hotplug(void)
2361 {
2362 	mutex_lock(&device_hotplug_lock);
2363 }
2364 
2365 void unlock_device_hotplug(void)
2366 {
2367 	mutex_unlock(&device_hotplug_lock);
2368 }
2369 
2370 int lock_device_hotplug_sysfs(void)
2371 {
2372 	if (mutex_trylock(&device_hotplug_lock))
2373 		return 0;
2374 
2375 	/* Avoid busy looping (5 ms of sleep should do). */
2376 	msleep(5);
2377 	return restart_syscall();
2378 }
2379 
2380 #ifdef CONFIG_BLOCK
2381 static inline int device_is_not_partition(struct device *dev)
2382 {
2383 	return !(dev->type == &part_type);
2384 }
2385 #else
2386 static inline int device_is_not_partition(struct device *dev)
2387 {
2388 	return 1;
2389 }
2390 #endif
2391 
2392 static void device_platform_notify(struct device *dev)
2393 {
2394 	acpi_device_notify(dev);
2395 
2396 	software_node_notify(dev);
2397 }
2398 
2399 static void device_platform_notify_remove(struct device *dev)
2400 {
2401 	software_node_notify_remove(dev);
2402 
2403 	acpi_device_notify_remove(dev);
2404 }
2405 
2406 /**
2407  * dev_driver_string - Return a device's driver name, if at all possible
2408  * @dev: struct device to get the name of
2409  *
2410  * Will return the device's driver's name if it is bound to a device.  If
2411  * the device is not bound to a driver, it will return the name of the bus
2412  * it is attached to.  If it is not attached to a bus either, an empty
2413  * string will be returned.
2414  */
2415 const char *dev_driver_string(const struct device *dev)
2416 {
2417 	struct device_driver *drv;
2418 
2419 	/* dev->driver can change to NULL underneath us because of unbinding,
2420 	 * so be careful about accessing it.  dev->bus and dev->class should
2421 	 * never change once they are set, so they don't need special care.
2422 	 */
2423 	drv = READ_ONCE(dev->driver);
2424 	return drv ? drv->name : dev_bus_name(dev);
2425 }
2426 EXPORT_SYMBOL(dev_driver_string);
2427 
2428 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
2429 
2430 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
2431 			     char *buf)
2432 {
2433 	struct device_attribute *dev_attr = to_dev_attr(attr);
2434 	struct device *dev = kobj_to_dev(kobj);
2435 	ssize_t ret = -EIO;
2436 
2437 	if (dev_attr->show)
2438 		ret = dev_attr->show(dev, dev_attr, buf);
2439 	if (ret >= (ssize_t)PAGE_SIZE) {
2440 		printk("dev_attr_show: %pS returned bad count\n",
2441 				dev_attr->show);
2442 	}
2443 	return ret;
2444 }
2445 
2446 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
2447 			      const char *buf, size_t count)
2448 {
2449 	struct device_attribute *dev_attr = to_dev_attr(attr);
2450 	struct device *dev = kobj_to_dev(kobj);
2451 	ssize_t ret = -EIO;
2452 
2453 	if (dev_attr->store)
2454 		ret = dev_attr->store(dev, dev_attr, buf, count);
2455 	return ret;
2456 }
2457 
2458 static const struct sysfs_ops dev_sysfs_ops = {
2459 	.show	= dev_attr_show,
2460 	.store	= dev_attr_store,
2461 };
2462 
2463 #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
2464 
2465 ssize_t device_store_ulong(struct device *dev,
2466 			   struct device_attribute *attr,
2467 			   const char *buf, size_t size)
2468 {
2469 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2470 	int ret;
2471 	unsigned long new;
2472 
2473 	ret = kstrtoul(buf, 0, &new);
2474 	if (ret)
2475 		return ret;
2476 	*(unsigned long *)(ea->var) = new;
2477 	/* Always return full write size even if we didn't consume all */
2478 	return size;
2479 }
2480 EXPORT_SYMBOL_GPL(device_store_ulong);
2481 
2482 ssize_t device_show_ulong(struct device *dev,
2483 			  struct device_attribute *attr,
2484 			  char *buf)
2485 {
2486 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2487 	return sysfs_emit(buf, "%lx\n", *(unsigned long *)(ea->var));
2488 }
2489 EXPORT_SYMBOL_GPL(device_show_ulong);
2490 
2491 ssize_t device_store_int(struct device *dev,
2492 			 struct device_attribute *attr,
2493 			 const char *buf, size_t size)
2494 {
2495 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2496 	int ret;
2497 	long new;
2498 
2499 	ret = kstrtol(buf, 0, &new);
2500 	if (ret)
2501 		return ret;
2502 
2503 	if (new > INT_MAX || new < INT_MIN)
2504 		return -EINVAL;
2505 	*(int *)(ea->var) = new;
2506 	/* Always return full write size even if we didn't consume all */
2507 	return size;
2508 }
2509 EXPORT_SYMBOL_GPL(device_store_int);
2510 
2511 ssize_t device_show_int(struct device *dev,
2512 			struct device_attribute *attr,
2513 			char *buf)
2514 {
2515 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2516 
2517 	return sysfs_emit(buf, "%d\n", *(int *)(ea->var));
2518 }
2519 EXPORT_SYMBOL_GPL(device_show_int);
2520 
2521 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
2522 			  const char *buf, size_t size)
2523 {
2524 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2525 
2526 	if (kstrtobool(buf, ea->var) < 0)
2527 		return -EINVAL;
2528 
2529 	return size;
2530 }
2531 EXPORT_SYMBOL_GPL(device_store_bool);
2532 
2533 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
2534 			 char *buf)
2535 {
2536 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2537 
2538 	return sysfs_emit(buf, "%d\n", *(bool *)(ea->var));
2539 }
2540 EXPORT_SYMBOL_GPL(device_show_bool);
2541 
2542 ssize_t device_show_string(struct device *dev,
2543 			   struct device_attribute *attr, char *buf)
2544 {
2545 	struct dev_ext_attribute *ea = to_ext_attr(attr);
2546 
2547 	return sysfs_emit(buf, "%s\n", (char *)ea->var);
2548 }
2549 EXPORT_SYMBOL_GPL(device_show_string);
2550 
2551 /**
2552  * device_release - free device structure.
2553  * @kobj: device's kobject.
2554  *
2555  * This is called once the reference count for the object
2556  * reaches 0. We forward the call to the device's release
2557  * method, which should handle actually freeing the structure.
2558  */
2559 static void device_release(struct kobject *kobj)
2560 {
2561 	struct device *dev = kobj_to_dev(kobj);
2562 	struct device_private *p = dev->p;
2563 
2564 	/*
2565 	 * Some platform devices are driven without driver attached
2566 	 * and managed resources may have been acquired.  Make sure
2567 	 * all resources are released.
2568 	 *
2569 	 * Drivers still can add resources into device after device
2570 	 * is deleted but alive, so release devres here to avoid
2571 	 * possible memory leak.
2572 	 */
2573 	devres_release_all(dev);
2574 
2575 	kfree(dev->dma_range_map);
2576 
2577 	if (dev->release)
2578 		dev->release(dev);
2579 	else if (dev->type && dev->type->release)
2580 		dev->type->release(dev);
2581 	else if (dev->class && dev->class->dev_release)
2582 		dev->class->dev_release(dev);
2583 	else
2584 		WARN(1, KERN_ERR "Device '%s' does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
2585 			dev_name(dev));
2586 	kfree(p);
2587 }
2588 
2589 static const void *device_namespace(const struct kobject *kobj)
2590 {
2591 	const struct device *dev = kobj_to_dev(kobj);
2592 	const void *ns = NULL;
2593 
2594 	if (dev->class && dev->class->ns_type)
2595 		ns = dev->class->namespace(dev);
2596 
2597 	return ns;
2598 }
2599 
2600 static void device_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
2601 {
2602 	const struct device *dev = kobj_to_dev(kobj);
2603 
2604 	if (dev->class && dev->class->get_ownership)
2605 		dev->class->get_ownership(dev, uid, gid);
2606 }
2607 
2608 static const struct kobj_type device_ktype = {
2609 	.release	= device_release,
2610 	.sysfs_ops	= &dev_sysfs_ops,
2611 	.namespace	= device_namespace,
2612 	.get_ownership	= device_get_ownership,
2613 };
2614 
2615 
2616 static int dev_uevent_filter(const struct kobject *kobj)
2617 {
2618 	const struct kobj_type *ktype = get_ktype(kobj);
2619 
2620 	if (ktype == &device_ktype) {
2621 		const struct device *dev = kobj_to_dev(kobj);
2622 		if (dev->bus)
2623 			return 1;
2624 		if (dev->class)
2625 			return 1;
2626 	}
2627 	return 0;
2628 }
2629 
2630 static const char *dev_uevent_name(const struct kobject *kobj)
2631 {
2632 	const struct device *dev = kobj_to_dev(kobj);
2633 
2634 	if (dev->bus)
2635 		return dev->bus->name;
2636 	if (dev->class)
2637 		return dev->class->name;
2638 	return NULL;
2639 }
2640 
2641 static int dev_uevent(const struct kobject *kobj, struct kobj_uevent_env *env)
2642 {
2643 	const struct device *dev = kobj_to_dev(kobj);
2644 	struct device_driver *driver;
2645 	int retval = 0;
2646 
2647 	/* add device node properties if present */
2648 	if (MAJOR(dev->devt)) {
2649 		const char *tmp;
2650 		const char *name;
2651 		umode_t mode = 0;
2652 		kuid_t uid = GLOBAL_ROOT_UID;
2653 		kgid_t gid = GLOBAL_ROOT_GID;
2654 
2655 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
2656 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
2657 		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
2658 		if (name) {
2659 			add_uevent_var(env, "DEVNAME=%s", name);
2660 			if (mode)
2661 				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
2662 			if (!uid_eq(uid, GLOBAL_ROOT_UID))
2663 				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
2664 			if (!gid_eq(gid, GLOBAL_ROOT_GID))
2665 				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
2666 			kfree(tmp);
2667 		}
2668 	}
2669 
2670 	if (dev->type && dev->type->name)
2671 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
2672 
2673 	/* Synchronize with module_remove_driver() */
2674 	rcu_read_lock();
2675 	driver = READ_ONCE(dev->driver);
2676 	if (driver)
2677 		add_uevent_var(env, "DRIVER=%s", driver->name);
2678 	rcu_read_unlock();
2679 
2680 	/* Add common DT information about the device */
2681 	of_device_uevent(dev, env);
2682 
2683 	/* have the bus specific function add its stuff */
2684 	if (dev->bus && dev->bus->uevent) {
2685 		retval = dev->bus->uevent(dev, env);
2686 		if (retval)
2687 			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
2688 				 dev_name(dev), __func__, retval);
2689 	}
2690 
2691 	/* have the class specific function add its stuff */
2692 	if (dev->class && dev->class->dev_uevent) {
2693 		retval = dev->class->dev_uevent(dev, env);
2694 		if (retval)
2695 			pr_debug("device: '%s': %s: class uevent() "
2696 				 "returned %d\n", dev_name(dev),
2697 				 __func__, retval);
2698 	}
2699 
2700 	/* have the device type specific function add its stuff */
2701 	if (dev->type && dev->type->uevent) {
2702 		retval = dev->type->uevent(dev, env);
2703 		if (retval)
2704 			pr_debug("device: '%s': %s: dev_type uevent() "
2705 				 "returned %d\n", dev_name(dev),
2706 				 __func__, retval);
2707 	}
2708 
2709 	return retval;
2710 }
2711 
2712 static const struct kset_uevent_ops device_uevent_ops = {
2713 	.filter =	dev_uevent_filter,
2714 	.name =		dev_uevent_name,
2715 	.uevent =	dev_uevent,
2716 };
2717 
2718 static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
2719 			   char *buf)
2720 {
2721 	struct kobject *top_kobj;
2722 	struct kset *kset;
2723 	struct kobj_uevent_env *env = NULL;
2724 	int i;
2725 	int len = 0;
2726 	int retval;
2727 
2728 	/* search the kset, the device belongs to */
2729 	top_kobj = &dev->kobj;
2730 	while (!top_kobj->kset && top_kobj->parent)
2731 		top_kobj = top_kobj->parent;
2732 	if (!top_kobj->kset)
2733 		goto out;
2734 
2735 	kset = top_kobj->kset;
2736 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
2737 		goto out;
2738 
2739 	/* respect filter */
2740 	if (kset->uevent_ops && kset->uevent_ops->filter)
2741 		if (!kset->uevent_ops->filter(&dev->kobj))
2742 			goto out;
2743 
2744 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
2745 	if (!env)
2746 		return -ENOMEM;
2747 
2748 	/* let the kset specific function add its keys */
2749 	retval = kset->uevent_ops->uevent(&dev->kobj, env);
2750 	if (retval)
2751 		goto out;
2752 
2753 	/* copy keys to file */
2754 	for (i = 0; i < env->envp_idx; i++)
2755 		len += sysfs_emit_at(buf, len, "%s\n", env->envp[i]);
2756 out:
2757 	kfree(env);
2758 	return len;
2759 }
2760 
2761 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
2762 			    const char *buf, size_t count)
2763 {
2764 	int rc;
2765 
2766 	rc = kobject_synth_uevent(&dev->kobj, buf, count);
2767 
2768 	if (rc) {
2769 		dev_err(dev, "uevent: failed to send synthetic uevent: %d\n", rc);
2770 		return rc;
2771 	}
2772 
2773 	return count;
2774 }
2775 static DEVICE_ATTR_RW(uevent);
2776 
2777 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
2778 			   char *buf)
2779 {
2780 	bool val;
2781 
2782 	device_lock(dev);
2783 	val = !dev->offline;
2784 	device_unlock(dev);
2785 	return sysfs_emit(buf, "%u\n", val);
2786 }
2787 
2788 static ssize_t online_store(struct device *dev, struct device_attribute *attr,
2789 			    const char *buf, size_t count)
2790 {
2791 	bool val;
2792 	int ret;
2793 
2794 	ret = kstrtobool(buf, &val);
2795 	if (ret < 0)
2796 		return ret;
2797 
2798 	ret = lock_device_hotplug_sysfs();
2799 	if (ret)
2800 		return ret;
2801 
2802 	ret = val ? device_online(dev) : device_offline(dev);
2803 	unlock_device_hotplug();
2804 	return ret < 0 ? ret : count;
2805 }
2806 static DEVICE_ATTR_RW(online);
2807 
2808 static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
2809 			      char *buf)
2810 {
2811 	const char *loc;
2812 
2813 	switch (dev->removable) {
2814 	case DEVICE_REMOVABLE:
2815 		loc = "removable";
2816 		break;
2817 	case DEVICE_FIXED:
2818 		loc = "fixed";
2819 		break;
2820 	default:
2821 		loc = "unknown";
2822 	}
2823 	return sysfs_emit(buf, "%s\n", loc);
2824 }
2825 static DEVICE_ATTR_RO(removable);
2826 
2827 int device_add_groups(struct device *dev, const struct attribute_group **groups)
2828 {
2829 	return sysfs_create_groups(&dev->kobj, groups);
2830 }
2831 EXPORT_SYMBOL_GPL(device_add_groups);
2832 
2833 void device_remove_groups(struct device *dev,
2834 			  const struct attribute_group **groups)
2835 {
2836 	sysfs_remove_groups(&dev->kobj, groups);
2837 }
2838 EXPORT_SYMBOL_GPL(device_remove_groups);
2839 
2840 union device_attr_group_devres {
2841 	const struct attribute_group *group;
2842 	const struct attribute_group **groups;
2843 };
2844 
2845 static void devm_attr_group_remove(struct device *dev, void *res)
2846 {
2847 	union device_attr_group_devres *devres = res;
2848 	const struct attribute_group *group = devres->group;
2849 
2850 	dev_dbg(dev, "%s: removing group %p\n", __func__, group);
2851 	sysfs_remove_group(&dev->kobj, group);
2852 }
2853 
2854 /**
2855  * devm_device_add_group - given a device, create a managed attribute group
2856  * @dev:	The device to create the group for
2857  * @grp:	The attribute group to create
2858  *
2859  * This function creates a group for the first time.  It will explicitly
2860  * warn and error if any of the attribute files being created already exist.
2861  *
2862  * Returns 0 on success or error code on failure.
2863  */
2864 int devm_device_add_group(struct device *dev, const struct attribute_group *grp)
2865 {
2866 	union device_attr_group_devres *devres;
2867 	int error;
2868 
2869 	devres = devres_alloc(devm_attr_group_remove,
2870 			      sizeof(*devres), GFP_KERNEL);
2871 	if (!devres)
2872 		return -ENOMEM;
2873 
2874 	error = sysfs_create_group(&dev->kobj, grp);
2875 	if (error) {
2876 		devres_free(devres);
2877 		return error;
2878 	}
2879 
2880 	devres->group = grp;
2881 	devres_add(dev, devres);
2882 	return 0;
2883 }
2884 EXPORT_SYMBOL_GPL(devm_device_add_group);
2885 
2886 static int device_add_attrs(struct device *dev)
2887 {
2888 	const struct class *class = dev->class;
2889 	const struct device_type *type = dev->type;
2890 	int error;
2891 
2892 	if (class) {
2893 		error = device_add_groups(dev, class->dev_groups);
2894 		if (error)
2895 			return error;
2896 	}
2897 
2898 	if (type) {
2899 		error = device_add_groups(dev, type->groups);
2900 		if (error)
2901 			goto err_remove_class_groups;
2902 	}
2903 
2904 	error = device_add_groups(dev, dev->groups);
2905 	if (error)
2906 		goto err_remove_type_groups;
2907 
2908 	if (device_supports_offline(dev) && !dev->offline_disabled) {
2909 		error = device_create_file(dev, &dev_attr_online);
2910 		if (error)
2911 			goto err_remove_dev_groups;
2912 	}
2913 
2914 	if (fw_devlink_flags && !fw_devlink_is_permissive() && dev->fwnode) {
2915 		error = device_create_file(dev, &dev_attr_waiting_for_supplier);
2916 		if (error)
2917 			goto err_remove_dev_online;
2918 	}
2919 
2920 	if (dev_removable_is_valid(dev)) {
2921 		error = device_create_file(dev, &dev_attr_removable);
2922 		if (error)
2923 			goto err_remove_dev_waiting_for_supplier;
2924 	}
2925 
2926 	if (dev_add_physical_location(dev)) {
2927 		error = device_add_group(dev,
2928 			&dev_attr_physical_location_group);
2929 		if (error)
2930 			goto err_remove_dev_removable;
2931 	}
2932 
2933 	return 0;
2934 
2935  err_remove_dev_removable:
2936 	device_remove_file(dev, &dev_attr_removable);
2937  err_remove_dev_waiting_for_supplier:
2938 	device_remove_file(dev, &dev_attr_waiting_for_supplier);
2939  err_remove_dev_online:
2940 	device_remove_file(dev, &dev_attr_online);
2941  err_remove_dev_groups:
2942 	device_remove_groups(dev, dev->groups);
2943  err_remove_type_groups:
2944 	if (type)
2945 		device_remove_groups(dev, type->groups);
2946  err_remove_class_groups:
2947 	if (class)
2948 		device_remove_groups(dev, class->dev_groups);
2949 
2950 	return error;
2951 }
2952 
2953 static void device_remove_attrs(struct device *dev)
2954 {
2955 	const struct class *class = dev->class;
2956 	const struct device_type *type = dev->type;
2957 
2958 	if (dev->physical_location) {
2959 		device_remove_group(dev, &dev_attr_physical_location_group);
2960 		kfree(dev->physical_location);
2961 	}
2962 
2963 	device_remove_file(dev, &dev_attr_removable);
2964 	device_remove_file(dev, &dev_attr_waiting_for_supplier);
2965 	device_remove_file(dev, &dev_attr_online);
2966 	device_remove_groups(dev, dev->groups);
2967 
2968 	if (type)
2969 		device_remove_groups(dev, type->groups);
2970 
2971 	if (class)
2972 		device_remove_groups(dev, class->dev_groups);
2973 }
2974 
2975 static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
2976 			char *buf)
2977 {
2978 	return print_dev_t(buf, dev->devt);
2979 }
2980 static DEVICE_ATTR_RO(dev);
2981 
2982 /* /sys/devices/ */
2983 struct kset *devices_kset;
2984 
2985 /**
2986  * devices_kset_move_before - Move device in the devices_kset's list.
2987  * @deva: Device to move.
2988  * @devb: Device @deva should come before.
2989  */
2990 static void devices_kset_move_before(struct device *deva, struct device *devb)
2991 {
2992 	if (!devices_kset)
2993 		return;
2994 	pr_debug("devices_kset: Moving %s before %s\n",
2995 		 dev_name(deva), dev_name(devb));
2996 	spin_lock(&devices_kset->list_lock);
2997 	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
2998 	spin_unlock(&devices_kset->list_lock);
2999 }
3000 
3001 /**
3002  * devices_kset_move_after - Move device in the devices_kset's list.
3003  * @deva: Device to move
3004  * @devb: Device @deva should come after.
3005  */
3006 static void devices_kset_move_after(struct device *deva, struct device *devb)
3007 {
3008 	if (!devices_kset)
3009 		return;
3010 	pr_debug("devices_kset: Moving %s after %s\n",
3011 		 dev_name(deva), dev_name(devb));
3012 	spin_lock(&devices_kset->list_lock);
3013 	list_move(&deva->kobj.entry, &devb->kobj.entry);
3014 	spin_unlock(&devices_kset->list_lock);
3015 }
3016 
3017 /**
3018  * devices_kset_move_last - move the device to the end of devices_kset's list.
3019  * @dev: device to move
3020  */
3021 void devices_kset_move_last(struct device *dev)
3022 {
3023 	if (!devices_kset)
3024 		return;
3025 	pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
3026 	spin_lock(&devices_kset->list_lock);
3027 	list_move_tail(&dev->kobj.entry, &devices_kset->list);
3028 	spin_unlock(&devices_kset->list_lock);
3029 }
3030 
3031 /**
3032  * device_create_file - create sysfs attribute file for device.
3033  * @dev: device.
3034  * @attr: device attribute descriptor.
3035  */
3036 int device_create_file(struct device *dev,
3037 		       const struct device_attribute *attr)
3038 {
3039 	int error = 0;
3040 
3041 	if (dev) {
3042 		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
3043 			"Attribute %s: write permission without 'store'\n",
3044 			attr->attr.name);
3045 		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
3046 			"Attribute %s: read permission without 'show'\n",
3047 			attr->attr.name);
3048 		error = sysfs_create_file(&dev->kobj, &attr->attr);
3049 	}
3050 
3051 	return error;
3052 }
3053 EXPORT_SYMBOL_GPL(device_create_file);
3054 
3055 /**
3056  * device_remove_file - remove sysfs attribute file.
3057  * @dev: device.
3058  * @attr: device attribute descriptor.
3059  */
3060 void device_remove_file(struct device *dev,
3061 			const struct device_attribute *attr)
3062 {
3063 	if (dev)
3064 		sysfs_remove_file(&dev->kobj, &attr->attr);
3065 }
3066 EXPORT_SYMBOL_GPL(device_remove_file);
3067 
3068 /**
3069  * device_remove_file_self - remove sysfs attribute file from its own method.
3070  * @dev: device.
3071  * @attr: device attribute descriptor.
3072  *
3073  * See kernfs_remove_self() for details.
3074  */
3075 bool device_remove_file_self(struct device *dev,
3076 			     const struct device_attribute *attr)
3077 {
3078 	if (dev)
3079 		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
3080 	else
3081 		return false;
3082 }
3083 EXPORT_SYMBOL_GPL(device_remove_file_self);
3084 
3085 /**
3086  * device_create_bin_file - create sysfs binary attribute file for device.
3087  * @dev: device.
3088  * @attr: device binary attribute descriptor.
3089  */
3090 int device_create_bin_file(struct device *dev,
3091 			   const struct bin_attribute *attr)
3092 {
3093 	int error = -EINVAL;
3094 	if (dev)
3095 		error = sysfs_create_bin_file(&dev->kobj, attr);
3096 	return error;
3097 }
3098 EXPORT_SYMBOL_GPL(device_create_bin_file);
3099 
3100 /**
3101  * device_remove_bin_file - remove sysfs binary attribute file
3102  * @dev: device.
3103  * @attr: device binary attribute descriptor.
3104  */
3105 void device_remove_bin_file(struct device *dev,
3106 			    const struct bin_attribute *attr)
3107 {
3108 	if (dev)
3109 		sysfs_remove_bin_file(&dev->kobj, attr);
3110 }
3111 EXPORT_SYMBOL_GPL(device_remove_bin_file);
3112 
3113 static void klist_children_get(struct klist_node *n)
3114 {
3115 	struct device_private *p = to_device_private_parent(n);
3116 	struct device *dev = p->device;
3117 
3118 	get_device(dev);
3119 }
3120 
3121 static void klist_children_put(struct klist_node *n)
3122 {
3123 	struct device_private *p = to_device_private_parent(n);
3124 	struct device *dev = p->device;
3125 
3126 	put_device(dev);
3127 }
3128 
3129 /**
3130  * device_initialize - init device structure.
3131  * @dev: device.
3132  *
3133  * This prepares the device for use by other layers by initializing
3134  * its fields.
3135  * It is the first half of device_register(), if called by
3136  * that function, though it can also be called separately, so one
3137  * may use @dev's fields. In particular, get_device()/put_device()
3138  * may be used for reference counting of @dev after calling this
3139  * function.
3140  *
3141  * All fields in @dev must be initialized by the caller to 0, except
3142  * for those explicitly set to some other value.  The simplest
3143  * approach is to use kzalloc() to allocate the structure containing
3144  * @dev.
3145  *
3146  * NOTE: Use put_device() to give up your reference instead of freeing
3147  * @dev directly once you have called this function.
3148  */
3149 void device_initialize(struct device *dev)
3150 {
3151 	dev->kobj.kset = devices_kset;
3152 	kobject_init(&dev->kobj, &device_ktype);
3153 	INIT_LIST_HEAD(&dev->dma_pools);
3154 	mutex_init(&dev->mutex);
3155 	lockdep_set_novalidate_class(&dev->mutex);
3156 	spin_lock_init(&dev->devres_lock);
3157 	INIT_LIST_HEAD(&dev->devres_head);
3158 	device_pm_init(dev);
3159 	set_dev_node(dev, NUMA_NO_NODE);
3160 	INIT_LIST_HEAD(&dev->links.consumers);
3161 	INIT_LIST_HEAD(&dev->links.suppliers);
3162 	INIT_LIST_HEAD(&dev->links.defer_sync);
3163 	dev->links.status = DL_DEV_NO_DRIVER;
3164 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
3165     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
3166     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
3167 	dev->dma_coherent = dma_default_coherent;
3168 #endif
3169 	swiotlb_dev_init(dev);
3170 }
3171 EXPORT_SYMBOL_GPL(device_initialize);
3172 
3173 struct kobject *virtual_device_parent(struct device *dev)
3174 {
3175 	static struct kobject *virtual_dir = NULL;
3176 
3177 	if (!virtual_dir)
3178 		virtual_dir = kobject_create_and_add("virtual",
3179 						     &devices_kset->kobj);
3180 
3181 	return virtual_dir;
3182 }
3183 
3184 struct class_dir {
3185 	struct kobject kobj;
3186 	const struct class *class;
3187 };
3188 
3189 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
3190 
3191 static void class_dir_release(struct kobject *kobj)
3192 {
3193 	struct class_dir *dir = to_class_dir(kobj);
3194 	kfree(dir);
3195 }
3196 
3197 static const
3198 struct kobj_ns_type_operations *class_dir_child_ns_type(const struct kobject *kobj)
3199 {
3200 	const struct class_dir *dir = to_class_dir(kobj);
3201 	return dir->class->ns_type;
3202 }
3203 
3204 static const struct kobj_type class_dir_ktype = {
3205 	.release	= class_dir_release,
3206 	.sysfs_ops	= &kobj_sysfs_ops,
3207 	.child_ns_type	= class_dir_child_ns_type
3208 };
3209 
3210 static struct kobject *class_dir_create_and_add(struct subsys_private *sp,
3211 						struct kobject *parent_kobj)
3212 {
3213 	struct class_dir *dir;
3214 	int retval;
3215 
3216 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
3217 	if (!dir)
3218 		return ERR_PTR(-ENOMEM);
3219 
3220 	dir->class = sp->class;
3221 	kobject_init(&dir->kobj, &class_dir_ktype);
3222 
3223 	dir->kobj.kset = &sp->glue_dirs;
3224 
3225 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", sp->class->name);
3226 	if (retval < 0) {
3227 		kobject_put(&dir->kobj);
3228 		return ERR_PTR(retval);
3229 	}
3230 	return &dir->kobj;
3231 }
3232 
3233 static DEFINE_MUTEX(gdp_mutex);
3234 
3235 static struct kobject *get_device_parent(struct device *dev,
3236 					 struct device *parent)
3237 {
3238 	struct subsys_private *sp = class_to_subsys(dev->class);
3239 	struct kobject *kobj = NULL;
3240 
3241 	if (sp) {
3242 		struct kobject *parent_kobj;
3243 		struct kobject *k;
3244 
3245 		/*
3246 		 * If we have no parent, we live in "virtual".
3247 		 * Class-devices with a non class-device as parent, live
3248 		 * in a "glue" directory to prevent namespace collisions.
3249 		 */
3250 		if (parent == NULL)
3251 			parent_kobj = virtual_device_parent(dev);
3252 		else if (parent->class && !dev->class->ns_type) {
3253 			subsys_put(sp);
3254 			return &parent->kobj;
3255 		} else {
3256 			parent_kobj = &parent->kobj;
3257 		}
3258 
3259 		mutex_lock(&gdp_mutex);
3260 
3261 		/* find our class-directory at the parent and reference it */
3262 		spin_lock(&sp->glue_dirs.list_lock);
3263 		list_for_each_entry(k, &sp->glue_dirs.list, entry)
3264 			if (k->parent == parent_kobj) {
3265 				kobj = kobject_get(k);
3266 				break;
3267 			}
3268 		spin_unlock(&sp->glue_dirs.list_lock);
3269 		if (kobj) {
3270 			mutex_unlock(&gdp_mutex);
3271 			subsys_put(sp);
3272 			return kobj;
3273 		}
3274 
3275 		/* or create a new class-directory at the parent device */
3276 		k = class_dir_create_and_add(sp, parent_kobj);
3277 		/* do not emit an uevent for this simple "glue" directory */
3278 		mutex_unlock(&gdp_mutex);
3279 		subsys_put(sp);
3280 		return k;
3281 	}
3282 
3283 	/* subsystems can specify a default root directory for their devices */
3284 	if (!parent && dev->bus) {
3285 		struct device *dev_root = bus_get_dev_root(dev->bus);
3286 
3287 		if (dev_root) {
3288 			kobj = &dev_root->kobj;
3289 			put_device(dev_root);
3290 			return kobj;
3291 		}
3292 	}
3293 
3294 	if (parent)
3295 		return &parent->kobj;
3296 	return NULL;
3297 }
3298 
3299 static inline bool live_in_glue_dir(struct kobject *kobj,
3300 				    struct device *dev)
3301 {
3302 	struct subsys_private *sp;
3303 	bool retval;
3304 
3305 	if (!kobj || !dev->class)
3306 		return false;
3307 
3308 	sp = class_to_subsys(dev->class);
3309 	if (!sp)
3310 		return false;
3311 
3312 	if (kobj->kset == &sp->glue_dirs)
3313 		retval = true;
3314 	else
3315 		retval = false;
3316 
3317 	subsys_put(sp);
3318 	return retval;
3319 }
3320 
3321 static inline struct kobject *get_glue_dir(struct device *dev)
3322 {
3323 	return dev->kobj.parent;
3324 }
3325 
3326 /**
3327  * kobject_has_children - Returns whether a kobject has children.
3328  * @kobj: the object to test
3329  *
3330  * This will return whether a kobject has other kobjects as children.
3331  *
3332  * It does NOT account for the presence of attribute files, only sub
3333  * directories. It also assumes there is no concurrent addition or
3334  * removal of such children, and thus relies on external locking.
3335  */
3336 static inline bool kobject_has_children(struct kobject *kobj)
3337 {
3338 	WARN_ON_ONCE(kref_read(&kobj->kref) == 0);
3339 
3340 	return kobj->sd && kobj->sd->dir.subdirs;
3341 }
3342 
3343 /*
3344  * make sure cleaning up dir as the last step, we need to make
3345  * sure .release handler of kobject is run with holding the
3346  * global lock
3347  */
3348 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
3349 {
3350 	unsigned int ref;
3351 
3352 	/* see if we live in a "glue" directory */
3353 	if (!live_in_glue_dir(glue_dir, dev))
3354 		return;
3355 
3356 	mutex_lock(&gdp_mutex);
3357 	/**
3358 	 * There is a race condition between removing glue directory
3359 	 * and adding a new device under the glue directory.
3360 	 *
3361 	 * CPU1:                                         CPU2:
3362 	 *
3363 	 * device_add()
3364 	 *   get_device_parent()
3365 	 *     class_dir_create_and_add()
3366 	 *       kobject_add_internal()
3367 	 *         create_dir()    // create glue_dir
3368 	 *
3369 	 *                                               device_add()
3370 	 *                                                 get_device_parent()
3371 	 *                                                   kobject_get() // get glue_dir
3372 	 *
3373 	 * device_del()
3374 	 *   cleanup_glue_dir()
3375 	 *     kobject_del(glue_dir)
3376 	 *
3377 	 *                                               kobject_add()
3378 	 *                                                 kobject_add_internal()
3379 	 *                                                   create_dir() // in glue_dir
3380 	 *                                                     sysfs_create_dir_ns()
3381 	 *                                                       kernfs_create_dir_ns(sd)
3382 	 *
3383 	 *       sysfs_remove_dir() // glue_dir->sd=NULL
3384 	 *       sysfs_put()        // free glue_dir->sd
3385 	 *
3386 	 *                                                         // sd is freed
3387 	 *                                                         kernfs_new_node(sd)
3388 	 *                                                           kernfs_get(glue_dir)
3389 	 *                                                           kernfs_add_one()
3390 	 *                                                           kernfs_put()
3391 	 *
3392 	 * Before CPU1 remove last child device under glue dir, if CPU2 add
3393 	 * a new device under glue dir, the glue_dir kobject reference count
3394 	 * will be increase to 2 in kobject_get(k). And CPU2 has been called
3395 	 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
3396 	 * and sysfs_put(). This result in glue_dir->sd is freed.
3397 	 *
3398 	 * Then the CPU2 will see a stale "empty" but still potentially used
3399 	 * glue dir around in kernfs_new_node().
3400 	 *
3401 	 * In order to avoid this happening, we also should make sure that
3402 	 * kernfs_node for glue_dir is released in CPU1 only when refcount
3403 	 * for glue_dir kobj is 1.
3404 	 */
3405 	ref = kref_read(&glue_dir->kref);
3406 	if (!kobject_has_children(glue_dir) && !--ref)
3407 		kobject_del(glue_dir);
3408 	kobject_put(glue_dir);
3409 	mutex_unlock(&gdp_mutex);
3410 }
3411 
3412 static int device_add_class_symlinks(struct device *dev)
3413 {
3414 	struct device_node *of_node = dev_of_node(dev);
3415 	struct subsys_private *sp;
3416 	int error;
3417 
3418 	if (of_node) {
3419 		error = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
3420 		if (error)
3421 			dev_warn(dev, "Error %d creating of_node link\n",error);
3422 		/* An error here doesn't warrant bringing down the device */
3423 	}
3424 
3425 	sp = class_to_subsys(dev->class);
3426 	if (!sp)
3427 		return 0;
3428 
3429 	error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
3430 	if (error)
3431 		goto out_devnode;
3432 
3433 	if (dev->parent && device_is_not_partition(dev)) {
3434 		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
3435 					  "device");
3436 		if (error)
3437 			goto out_subsys;
3438 	}
3439 
3440 	/* link in the class directory pointing to the device */
3441 	error = sysfs_create_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3442 	if (error)
3443 		goto out_device;
3444 	goto exit;
3445 
3446 out_device:
3447 	sysfs_remove_link(&dev->kobj, "device");
3448 out_subsys:
3449 	sysfs_remove_link(&dev->kobj, "subsystem");
3450 out_devnode:
3451 	sysfs_remove_link(&dev->kobj, "of_node");
3452 exit:
3453 	subsys_put(sp);
3454 	return error;
3455 }
3456 
3457 static void device_remove_class_symlinks(struct device *dev)
3458 {
3459 	struct subsys_private *sp = class_to_subsys(dev->class);
3460 
3461 	if (dev_of_node(dev))
3462 		sysfs_remove_link(&dev->kobj, "of_node");
3463 
3464 	if (!sp)
3465 		return;
3466 
3467 	if (dev->parent && device_is_not_partition(dev))
3468 		sysfs_remove_link(&dev->kobj, "device");
3469 	sysfs_remove_link(&dev->kobj, "subsystem");
3470 	sysfs_delete_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3471 	subsys_put(sp);
3472 }
3473 
3474 /**
3475  * dev_set_name - set a device name
3476  * @dev: device
3477  * @fmt: format string for the device's name
3478  */
3479 int dev_set_name(struct device *dev, const char *fmt, ...)
3480 {
3481 	va_list vargs;
3482 	int err;
3483 
3484 	va_start(vargs, fmt);
3485 	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
3486 	va_end(vargs);
3487 	return err;
3488 }
3489 EXPORT_SYMBOL_GPL(dev_set_name);
3490 
3491 /* select a /sys/dev/ directory for the device */
3492 static struct kobject *device_to_dev_kobj(struct device *dev)
3493 {
3494 	if (is_blockdev(dev))
3495 		return sysfs_dev_block_kobj;
3496 	else
3497 		return sysfs_dev_char_kobj;
3498 }
3499 
3500 static int device_create_sys_dev_entry(struct device *dev)
3501 {
3502 	struct kobject *kobj = device_to_dev_kobj(dev);
3503 	int error = 0;
3504 	char devt_str[15];
3505 
3506 	if (kobj) {
3507 		format_dev_t(devt_str, dev->devt);
3508 		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
3509 	}
3510 
3511 	return error;
3512 }
3513 
3514 static void device_remove_sys_dev_entry(struct device *dev)
3515 {
3516 	struct kobject *kobj = device_to_dev_kobj(dev);
3517 	char devt_str[15];
3518 
3519 	if (kobj) {
3520 		format_dev_t(devt_str, dev->devt);
3521 		sysfs_remove_link(kobj, devt_str);
3522 	}
3523 }
3524 
3525 static int device_private_init(struct device *dev)
3526 {
3527 	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
3528 	if (!dev->p)
3529 		return -ENOMEM;
3530 	dev->p->device = dev;
3531 	klist_init(&dev->p->klist_children, klist_children_get,
3532 		   klist_children_put);
3533 	INIT_LIST_HEAD(&dev->p->deferred_probe);
3534 	return 0;
3535 }
3536 
3537 /**
3538  * device_add - add device to device hierarchy.
3539  * @dev: device.
3540  *
3541  * This is part 2 of device_register(), though may be called
3542  * separately _iff_ device_initialize() has been called separately.
3543  *
3544  * This adds @dev to the kobject hierarchy via kobject_add(), adds it
3545  * to the global and sibling lists for the device, then
3546  * adds it to the other relevant subsystems of the driver model.
3547  *
3548  * Do not call this routine or device_register() more than once for
3549  * any device structure.  The driver model core is not designed to work
3550  * with devices that get unregistered and then spring back to life.
3551  * (Among other things, it's very hard to guarantee that all references
3552  * to the previous incarnation of @dev have been dropped.)  Allocate
3553  * and register a fresh new struct device instead.
3554  *
3555  * NOTE: _Never_ directly free @dev after calling this function, even
3556  * if it returned an error! Always use put_device() to give up your
3557  * reference instead.
3558  *
3559  * Rule of thumb is: if device_add() succeeds, you should call
3560  * device_del() when you want to get rid of it. If device_add() has
3561  * *not* succeeded, use *only* put_device() to drop the reference
3562  * count.
3563  */
3564 int device_add(struct device *dev)
3565 {
3566 	struct subsys_private *sp;
3567 	struct device *parent;
3568 	struct kobject *kobj;
3569 	struct class_interface *class_intf;
3570 	int error = -EINVAL;
3571 	struct kobject *glue_dir = NULL;
3572 
3573 	dev = get_device(dev);
3574 	if (!dev)
3575 		goto done;
3576 
3577 	if (!dev->p) {
3578 		error = device_private_init(dev);
3579 		if (error)
3580 			goto done;
3581 	}
3582 
3583 	/*
3584 	 * for statically allocated devices, which should all be converted
3585 	 * some day, we need to initialize the name. We prevent reading back
3586 	 * the name, and force the use of dev_name()
3587 	 */
3588 	if (dev->init_name) {
3589 		error = dev_set_name(dev, "%s", dev->init_name);
3590 		dev->init_name = NULL;
3591 	}
3592 
3593 	if (dev_name(dev))
3594 		error = 0;
3595 	/* subsystems can specify simple device enumeration */
3596 	else if (dev->bus && dev->bus->dev_name)
3597 		error = dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
3598 	else
3599 		error = -EINVAL;
3600 	if (error)
3601 		goto name_error;
3602 
3603 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3604 
3605 	parent = get_device(dev->parent);
3606 	kobj = get_device_parent(dev, parent);
3607 	if (IS_ERR(kobj)) {
3608 		error = PTR_ERR(kobj);
3609 		goto parent_error;
3610 	}
3611 	if (kobj)
3612 		dev->kobj.parent = kobj;
3613 
3614 	/* use parent numa_node */
3615 	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
3616 		set_dev_node(dev, dev_to_node(parent));
3617 
3618 	/* first, register with generic layer. */
3619 	/* we require the name to be set before, and pass NULL */
3620 	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
3621 	if (error) {
3622 		glue_dir = kobj;
3623 		goto Error;
3624 	}
3625 
3626 	/* notify platform of device entry */
3627 	device_platform_notify(dev);
3628 
3629 	error = device_create_file(dev, &dev_attr_uevent);
3630 	if (error)
3631 		goto attrError;
3632 
3633 	error = device_add_class_symlinks(dev);
3634 	if (error)
3635 		goto SymlinkError;
3636 	error = device_add_attrs(dev);
3637 	if (error)
3638 		goto AttrsError;
3639 	error = bus_add_device(dev);
3640 	if (error)
3641 		goto BusError;
3642 	error = dpm_sysfs_add(dev);
3643 	if (error)
3644 		goto DPMError;
3645 	device_pm_add(dev);
3646 
3647 	if (MAJOR(dev->devt)) {
3648 		error = device_create_file(dev, &dev_attr_dev);
3649 		if (error)
3650 			goto DevAttrError;
3651 
3652 		error = device_create_sys_dev_entry(dev);
3653 		if (error)
3654 			goto SysEntryError;
3655 
3656 		devtmpfs_create_node(dev);
3657 	}
3658 
3659 	/* Notify clients of device addition.  This call must come
3660 	 * after dpm_sysfs_add() and before kobject_uevent().
3661 	 */
3662 	bus_notify(dev, BUS_NOTIFY_ADD_DEVICE);
3663 	kobject_uevent(&dev->kobj, KOBJ_ADD);
3664 
3665 	/*
3666 	 * Check if any of the other devices (consumers) have been waiting for
3667 	 * this device (supplier) to be added so that they can create a device
3668 	 * link to it.
3669 	 *
3670 	 * This needs to happen after device_pm_add() because device_link_add()
3671 	 * requires the supplier be registered before it's called.
3672 	 *
3673 	 * But this also needs to happen before bus_probe_device() to make sure
3674 	 * waiting consumers can link to it before the driver is bound to the
3675 	 * device and the driver sync_state callback is called for this device.
3676 	 */
3677 	if (dev->fwnode && !dev->fwnode->dev) {
3678 		dev->fwnode->dev = dev;
3679 		fw_devlink_link_device(dev);
3680 	}
3681 
3682 	bus_probe_device(dev);
3683 
3684 	/*
3685 	 * If all driver registration is done and a newly added device doesn't
3686 	 * match with any driver, don't block its consumers from probing in
3687 	 * case the consumer device is able to operate without this supplier.
3688 	 */
3689 	if (dev->fwnode && fw_devlink_drv_reg_done && !dev->can_match)
3690 		fw_devlink_unblock_consumers(dev);
3691 
3692 	if (parent)
3693 		klist_add_tail(&dev->p->knode_parent,
3694 			       &parent->p->klist_children);
3695 
3696 	sp = class_to_subsys(dev->class);
3697 	if (sp) {
3698 		mutex_lock(&sp->mutex);
3699 		/* tie the class to the device */
3700 		klist_add_tail(&dev->p->knode_class, &sp->klist_devices);
3701 
3702 		/* notify any interfaces that the device is here */
3703 		list_for_each_entry(class_intf, &sp->interfaces, node)
3704 			if (class_intf->add_dev)
3705 				class_intf->add_dev(dev);
3706 		mutex_unlock(&sp->mutex);
3707 		subsys_put(sp);
3708 	}
3709 done:
3710 	put_device(dev);
3711 	return error;
3712  SysEntryError:
3713 	if (MAJOR(dev->devt))
3714 		device_remove_file(dev, &dev_attr_dev);
3715  DevAttrError:
3716 	device_pm_remove(dev);
3717 	dpm_sysfs_remove(dev);
3718  DPMError:
3719 	dev->driver = NULL;
3720 	bus_remove_device(dev);
3721  BusError:
3722 	device_remove_attrs(dev);
3723  AttrsError:
3724 	device_remove_class_symlinks(dev);
3725  SymlinkError:
3726 	device_remove_file(dev, &dev_attr_uevent);
3727  attrError:
3728 	device_platform_notify_remove(dev);
3729 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3730 	glue_dir = get_glue_dir(dev);
3731 	kobject_del(&dev->kobj);
3732  Error:
3733 	cleanup_glue_dir(dev, glue_dir);
3734 parent_error:
3735 	put_device(parent);
3736 name_error:
3737 	kfree(dev->p);
3738 	dev->p = NULL;
3739 	goto done;
3740 }
3741 EXPORT_SYMBOL_GPL(device_add);
3742 
3743 /**
3744  * device_register - register a device with the system.
3745  * @dev: pointer to the device structure
3746  *
3747  * This happens in two clean steps - initialize the device
3748  * and add it to the system. The two steps can be called
3749  * separately, but this is the easiest and most common.
3750  * I.e. you should only call the two helpers separately if
3751  * have a clearly defined need to use and refcount the device
3752  * before it is added to the hierarchy.
3753  *
3754  * For more information, see the kerneldoc for device_initialize()
3755  * and device_add().
3756  *
3757  * NOTE: _Never_ directly free @dev after calling this function, even
3758  * if it returned an error! Always use put_device() to give up the
3759  * reference initialized in this function instead.
3760  */
3761 int device_register(struct device *dev)
3762 {
3763 	device_initialize(dev);
3764 	return device_add(dev);
3765 }
3766 EXPORT_SYMBOL_GPL(device_register);
3767 
3768 /**
3769  * get_device - increment reference count for device.
3770  * @dev: device.
3771  *
3772  * This simply forwards the call to kobject_get(), though
3773  * we do take care to provide for the case that we get a NULL
3774  * pointer passed in.
3775  */
3776 struct device *get_device(struct device *dev)
3777 {
3778 	return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
3779 }
3780 EXPORT_SYMBOL_GPL(get_device);
3781 
3782 /**
3783  * put_device - decrement reference count.
3784  * @dev: device in question.
3785  */
3786 void put_device(struct device *dev)
3787 {
3788 	/* might_sleep(); */
3789 	if (dev)
3790 		kobject_put(&dev->kobj);
3791 }
3792 EXPORT_SYMBOL_GPL(put_device);
3793 
3794 bool kill_device(struct device *dev)
3795 {
3796 	/*
3797 	 * Require the device lock and set the "dead" flag to guarantee that
3798 	 * the update behavior is consistent with the other bitfields near
3799 	 * it and that we cannot have an asynchronous probe routine trying
3800 	 * to run while we are tearing out the bus/class/sysfs from
3801 	 * underneath the device.
3802 	 */
3803 	device_lock_assert(dev);
3804 
3805 	if (dev->p->dead)
3806 		return false;
3807 	dev->p->dead = true;
3808 	return true;
3809 }
3810 EXPORT_SYMBOL_GPL(kill_device);
3811 
3812 /**
3813  * device_del - delete device from system.
3814  * @dev: device.
3815  *
3816  * This is the first part of the device unregistration
3817  * sequence. This removes the device from the lists we control
3818  * from here, has it removed from the other driver model
3819  * subsystems it was added to in device_add(), and removes it
3820  * from the kobject hierarchy.
3821  *
3822  * NOTE: this should be called manually _iff_ device_add() was
3823  * also called manually.
3824  */
3825 void device_del(struct device *dev)
3826 {
3827 	struct subsys_private *sp;
3828 	struct device *parent = dev->parent;
3829 	struct kobject *glue_dir = NULL;
3830 	struct class_interface *class_intf;
3831 	unsigned int noio_flag;
3832 
3833 	device_lock(dev);
3834 	kill_device(dev);
3835 	device_unlock(dev);
3836 
3837 	if (dev->fwnode && dev->fwnode->dev == dev)
3838 		dev->fwnode->dev = NULL;
3839 
3840 	/* Notify clients of device removal.  This call must come
3841 	 * before dpm_sysfs_remove().
3842 	 */
3843 	noio_flag = memalloc_noio_save();
3844 	bus_notify(dev, BUS_NOTIFY_DEL_DEVICE);
3845 
3846 	dpm_sysfs_remove(dev);
3847 	if (parent)
3848 		klist_del(&dev->p->knode_parent);
3849 	if (MAJOR(dev->devt)) {
3850 		devtmpfs_delete_node(dev);
3851 		device_remove_sys_dev_entry(dev);
3852 		device_remove_file(dev, &dev_attr_dev);
3853 	}
3854 
3855 	sp = class_to_subsys(dev->class);
3856 	if (sp) {
3857 		device_remove_class_symlinks(dev);
3858 
3859 		mutex_lock(&sp->mutex);
3860 		/* notify any interfaces that the device is now gone */
3861 		list_for_each_entry(class_intf, &sp->interfaces, node)
3862 			if (class_intf->remove_dev)
3863 				class_intf->remove_dev(dev);
3864 		/* remove the device from the class list */
3865 		klist_del(&dev->p->knode_class);
3866 		mutex_unlock(&sp->mutex);
3867 		subsys_put(sp);
3868 	}
3869 	device_remove_file(dev, &dev_attr_uevent);
3870 	device_remove_attrs(dev);
3871 	bus_remove_device(dev);
3872 	device_pm_remove(dev);
3873 	driver_deferred_probe_del(dev);
3874 	device_platform_notify_remove(dev);
3875 	device_links_purge(dev);
3876 
3877 	/*
3878 	 * If a device does not have a driver attached, we need to clean
3879 	 * up any managed resources. We do this in device_release(), but
3880 	 * it's never called (and we leak the device) if a managed
3881 	 * resource holds a reference to the device. So release all
3882 	 * managed resources here, like we do in driver_detach(). We
3883 	 * still need to do so again in device_release() in case someone
3884 	 * adds a new resource after this point, though.
3885 	 */
3886 	devres_release_all(dev);
3887 
3888 	bus_notify(dev, BUS_NOTIFY_REMOVED_DEVICE);
3889 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3890 	glue_dir = get_glue_dir(dev);
3891 	kobject_del(&dev->kobj);
3892 	cleanup_glue_dir(dev, glue_dir);
3893 	memalloc_noio_restore(noio_flag);
3894 	put_device(parent);
3895 }
3896 EXPORT_SYMBOL_GPL(device_del);
3897 
3898 /**
3899  * device_unregister - unregister device from system.
3900  * @dev: device going away.
3901  *
3902  * We do this in two parts, like we do device_register(). First,
3903  * we remove it from all the subsystems with device_del(), then
3904  * we decrement the reference count via put_device(). If that
3905  * is the final reference count, the device will be cleaned up
3906  * via device_release() above. Otherwise, the structure will
3907  * stick around until the final reference to the device is dropped.
3908  */
3909 void device_unregister(struct device *dev)
3910 {
3911 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3912 	device_del(dev);
3913 	put_device(dev);
3914 }
3915 EXPORT_SYMBOL_GPL(device_unregister);
3916 
3917 static struct device *prev_device(struct klist_iter *i)
3918 {
3919 	struct klist_node *n = klist_prev(i);
3920 	struct device *dev = NULL;
3921 	struct device_private *p;
3922 
3923 	if (n) {
3924 		p = to_device_private_parent(n);
3925 		dev = p->device;
3926 	}
3927 	return dev;
3928 }
3929 
3930 static struct device *next_device(struct klist_iter *i)
3931 {
3932 	struct klist_node *n = klist_next(i);
3933 	struct device *dev = NULL;
3934 	struct device_private *p;
3935 
3936 	if (n) {
3937 		p = to_device_private_parent(n);
3938 		dev = p->device;
3939 	}
3940 	return dev;
3941 }
3942 
3943 /**
3944  * device_get_devnode - path of device node file
3945  * @dev: device
3946  * @mode: returned file access mode
3947  * @uid: returned file owner
3948  * @gid: returned file group
3949  * @tmp: possibly allocated string
3950  *
3951  * Return the relative path of a possible device node.
3952  * Non-default names may need to allocate a memory to compose
3953  * a name. This memory is returned in tmp and needs to be
3954  * freed by the caller.
3955  */
3956 const char *device_get_devnode(const struct device *dev,
3957 			       umode_t *mode, kuid_t *uid, kgid_t *gid,
3958 			       const char **tmp)
3959 {
3960 	char *s;
3961 
3962 	*tmp = NULL;
3963 
3964 	/* the device type may provide a specific name */
3965 	if (dev->type && dev->type->devnode)
3966 		*tmp = dev->type->devnode(dev, mode, uid, gid);
3967 	if (*tmp)
3968 		return *tmp;
3969 
3970 	/* the class may provide a specific name */
3971 	if (dev->class && dev->class->devnode)
3972 		*tmp = dev->class->devnode(dev, mode);
3973 	if (*tmp)
3974 		return *tmp;
3975 
3976 	/* return name without allocation, tmp == NULL */
3977 	if (strchr(dev_name(dev), '!') == NULL)
3978 		return dev_name(dev);
3979 
3980 	/* replace '!' in the name with '/' */
3981 	s = kstrdup_and_replace(dev_name(dev), '!', '/', GFP_KERNEL);
3982 	if (!s)
3983 		return NULL;
3984 	return *tmp = s;
3985 }
3986 
3987 /**
3988  * device_for_each_child - device child iterator.
3989  * @parent: parent struct device.
3990  * @fn: function to be called for each device.
3991  * @data: data for the callback.
3992  *
3993  * Iterate over @parent's child devices, and call @fn for each,
3994  * passing it @data.
3995  *
3996  * We check the return of @fn each time. If it returns anything
3997  * other than 0, we break out and return that value.
3998  */
3999 int device_for_each_child(struct device *parent, void *data,
4000 			  int (*fn)(struct device *dev, void *data))
4001 {
4002 	struct klist_iter i;
4003 	struct device *child;
4004 	int error = 0;
4005 
4006 	if (!parent->p)
4007 		return 0;
4008 
4009 	klist_iter_init(&parent->p->klist_children, &i);
4010 	while (!error && (child = next_device(&i)))
4011 		error = fn(child, data);
4012 	klist_iter_exit(&i);
4013 	return error;
4014 }
4015 EXPORT_SYMBOL_GPL(device_for_each_child);
4016 
4017 /**
4018  * device_for_each_child_reverse - device child iterator in reversed order.
4019  * @parent: parent struct device.
4020  * @fn: function to be called for each device.
4021  * @data: data for the callback.
4022  *
4023  * Iterate over @parent's child devices, and call @fn for each,
4024  * passing it @data.
4025  *
4026  * We check the return of @fn each time. If it returns anything
4027  * other than 0, we break out and return that value.
4028  */
4029 int device_for_each_child_reverse(struct device *parent, void *data,
4030 				  int (*fn)(struct device *dev, void *data))
4031 {
4032 	struct klist_iter i;
4033 	struct device *child;
4034 	int error = 0;
4035 
4036 	if (!parent->p)
4037 		return 0;
4038 
4039 	klist_iter_init(&parent->p->klist_children, &i);
4040 	while ((child = prev_device(&i)) && !error)
4041 		error = fn(child, data);
4042 	klist_iter_exit(&i);
4043 	return error;
4044 }
4045 EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
4046 
4047 /**
4048  * device_find_child - device iterator for locating a particular device.
4049  * @parent: parent struct device
4050  * @match: Callback function to check device
4051  * @data: Data to pass to match function
4052  *
4053  * This is similar to the device_for_each_child() function above, but it
4054  * returns a reference to a device that is 'found' for later use, as
4055  * determined by the @match callback.
4056  *
4057  * The callback should return 0 if the device doesn't match and non-zero
4058  * if it does.  If the callback returns non-zero and a reference to the
4059  * current device can be obtained, this function will return to the caller
4060  * and not iterate over any more devices.
4061  *
4062  * NOTE: you will need to drop the reference with put_device() after use.
4063  */
4064 struct device *device_find_child(struct device *parent, void *data,
4065 				 int (*match)(struct device *dev, void *data))
4066 {
4067 	struct klist_iter i;
4068 	struct device *child;
4069 
4070 	if (!parent)
4071 		return NULL;
4072 
4073 	klist_iter_init(&parent->p->klist_children, &i);
4074 	while ((child = next_device(&i)))
4075 		if (match(child, data) && get_device(child))
4076 			break;
4077 	klist_iter_exit(&i);
4078 	return child;
4079 }
4080 EXPORT_SYMBOL_GPL(device_find_child);
4081 
4082 /**
4083  * device_find_child_by_name - device iterator for locating a child device.
4084  * @parent: parent struct device
4085  * @name: name of the child device
4086  *
4087  * This is similar to the device_find_child() function above, but it
4088  * returns a reference to a device that has the name @name.
4089  *
4090  * NOTE: you will need to drop the reference with put_device() after use.
4091  */
4092 struct device *device_find_child_by_name(struct device *parent,
4093 					 const char *name)
4094 {
4095 	struct klist_iter i;
4096 	struct device *child;
4097 
4098 	if (!parent)
4099 		return NULL;
4100 
4101 	klist_iter_init(&parent->p->klist_children, &i);
4102 	while ((child = next_device(&i)))
4103 		if (sysfs_streq(dev_name(child), name) && get_device(child))
4104 			break;
4105 	klist_iter_exit(&i);
4106 	return child;
4107 }
4108 EXPORT_SYMBOL_GPL(device_find_child_by_name);
4109 
4110 static int match_any(struct device *dev, void *unused)
4111 {
4112 	return 1;
4113 }
4114 
4115 /**
4116  * device_find_any_child - device iterator for locating a child device, if any.
4117  * @parent: parent struct device
4118  *
4119  * This is similar to the device_find_child() function above, but it
4120  * returns a reference to a child device, if any.
4121  *
4122  * NOTE: you will need to drop the reference with put_device() after use.
4123  */
4124 struct device *device_find_any_child(struct device *parent)
4125 {
4126 	return device_find_child(parent, NULL, match_any);
4127 }
4128 EXPORT_SYMBOL_GPL(device_find_any_child);
4129 
4130 int __init devices_init(void)
4131 {
4132 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
4133 	if (!devices_kset)
4134 		return -ENOMEM;
4135 	dev_kobj = kobject_create_and_add("dev", NULL);
4136 	if (!dev_kobj)
4137 		goto dev_kobj_err;
4138 	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
4139 	if (!sysfs_dev_block_kobj)
4140 		goto block_kobj_err;
4141 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
4142 	if (!sysfs_dev_char_kobj)
4143 		goto char_kobj_err;
4144 	device_link_wq = alloc_workqueue("device_link_wq", 0, 0);
4145 	if (!device_link_wq)
4146 		goto wq_err;
4147 
4148 	return 0;
4149 
4150  wq_err:
4151 	kobject_put(sysfs_dev_char_kobj);
4152  char_kobj_err:
4153 	kobject_put(sysfs_dev_block_kobj);
4154  block_kobj_err:
4155 	kobject_put(dev_kobj);
4156  dev_kobj_err:
4157 	kset_unregister(devices_kset);
4158 	return -ENOMEM;
4159 }
4160 
4161 static int device_check_offline(struct device *dev, void *not_used)
4162 {
4163 	int ret;
4164 
4165 	ret = device_for_each_child(dev, NULL, device_check_offline);
4166 	if (ret)
4167 		return ret;
4168 
4169 	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
4170 }
4171 
4172 /**
4173  * device_offline - Prepare the device for hot-removal.
4174  * @dev: Device to be put offline.
4175  *
4176  * Execute the device bus type's .offline() callback, if present, to prepare
4177  * the device for a subsequent hot-removal.  If that succeeds, the device must
4178  * not be used until either it is removed or its bus type's .online() callback
4179  * is executed.
4180  *
4181  * Call under device_hotplug_lock.
4182  */
4183 int device_offline(struct device *dev)
4184 {
4185 	int ret;
4186 
4187 	if (dev->offline_disabled)
4188 		return -EPERM;
4189 
4190 	ret = device_for_each_child(dev, NULL, device_check_offline);
4191 	if (ret)
4192 		return ret;
4193 
4194 	device_lock(dev);
4195 	if (device_supports_offline(dev)) {
4196 		if (dev->offline) {
4197 			ret = 1;
4198 		} else {
4199 			ret = dev->bus->offline(dev);
4200 			if (!ret) {
4201 				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
4202 				dev->offline = true;
4203 			}
4204 		}
4205 	}
4206 	device_unlock(dev);
4207 
4208 	return ret;
4209 }
4210 
4211 /**
4212  * device_online - Put the device back online after successful device_offline().
4213  * @dev: Device to be put back online.
4214  *
4215  * If device_offline() has been successfully executed for @dev, but the device
4216  * has not been removed subsequently, execute its bus type's .online() callback
4217  * to indicate that the device can be used again.
4218  *
4219  * Call under device_hotplug_lock.
4220  */
4221 int device_online(struct device *dev)
4222 {
4223 	int ret = 0;
4224 
4225 	device_lock(dev);
4226 	if (device_supports_offline(dev)) {
4227 		if (dev->offline) {
4228 			ret = dev->bus->online(dev);
4229 			if (!ret) {
4230 				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
4231 				dev->offline = false;
4232 			}
4233 		} else {
4234 			ret = 1;
4235 		}
4236 	}
4237 	device_unlock(dev);
4238 
4239 	return ret;
4240 }
4241 
4242 struct root_device {
4243 	struct device dev;
4244 	struct module *owner;
4245 };
4246 
4247 static inline struct root_device *to_root_device(struct device *d)
4248 {
4249 	return container_of(d, struct root_device, dev);
4250 }
4251 
4252 static void root_device_release(struct device *dev)
4253 {
4254 	kfree(to_root_device(dev));
4255 }
4256 
4257 /**
4258  * __root_device_register - allocate and register a root device
4259  * @name: root device name
4260  * @owner: owner module of the root device, usually THIS_MODULE
4261  *
4262  * This function allocates a root device and registers it
4263  * using device_register(). In order to free the returned
4264  * device, use root_device_unregister().
4265  *
4266  * Root devices are dummy devices which allow other devices
4267  * to be grouped under /sys/devices. Use this function to
4268  * allocate a root device and then use it as the parent of
4269  * any device which should appear under /sys/devices/{name}
4270  *
4271  * The /sys/devices/{name} directory will also contain a
4272  * 'module' symlink which points to the @owner directory
4273  * in sysfs.
4274  *
4275  * Returns &struct device pointer on success, or ERR_PTR() on error.
4276  *
4277  * Note: You probably want to use root_device_register().
4278  */
4279 struct device *__root_device_register(const char *name, struct module *owner)
4280 {
4281 	struct root_device *root;
4282 	int err = -ENOMEM;
4283 
4284 	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
4285 	if (!root)
4286 		return ERR_PTR(err);
4287 
4288 	err = dev_set_name(&root->dev, "%s", name);
4289 	if (err) {
4290 		kfree(root);
4291 		return ERR_PTR(err);
4292 	}
4293 
4294 	root->dev.release = root_device_release;
4295 
4296 	err = device_register(&root->dev);
4297 	if (err) {
4298 		put_device(&root->dev);
4299 		return ERR_PTR(err);
4300 	}
4301 
4302 #ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
4303 	if (owner) {
4304 		struct module_kobject *mk = &owner->mkobj;
4305 
4306 		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
4307 		if (err) {
4308 			device_unregister(&root->dev);
4309 			return ERR_PTR(err);
4310 		}
4311 		root->owner = owner;
4312 	}
4313 #endif
4314 
4315 	return &root->dev;
4316 }
4317 EXPORT_SYMBOL_GPL(__root_device_register);
4318 
4319 /**
4320  * root_device_unregister - unregister and free a root device
4321  * @dev: device going away
4322  *
4323  * This function unregisters and cleans up a device that was created by
4324  * root_device_register().
4325  */
4326 void root_device_unregister(struct device *dev)
4327 {
4328 	struct root_device *root = to_root_device(dev);
4329 
4330 	if (root->owner)
4331 		sysfs_remove_link(&root->dev.kobj, "module");
4332 
4333 	device_unregister(dev);
4334 }
4335 EXPORT_SYMBOL_GPL(root_device_unregister);
4336 
4337 
4338 static void device_create_release(struct device *dev)
4339 {
4340 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
4341 	kfree(dev);
4342 }
4343 
4344 static __printf(6, 0) struct device *
4345 device_create_groups_vargs(const struct class *class, struct device *parent,
4346 			   dev_t devt, void *drvdata,
4347 			   const struct attribute_group **groups,
4348 			   const char *fmt, va_list args)
4349 {
4350 	struct device *dev = NULL;
4351 	int retval = -ENODEV;
4352 
4353 	if (IS_ERR_OR_NULL(class))
4354 		goto error;
4355 
4356 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
4357 	if (!dev) {
4358 		retval = -ENOMEM;
4359 		goto error;
4360 	}
4361 
4362 	device_initialize(dev);
4363 	dev->devt = devt;
4364 	dev->class = class;
4365 	dev->parent = parent;
4366 	dev->groups = groups;
4367 	dev->release = device_create_release;
4368 	dev_set_drvdata(dev, drvdata);
4369 
4370 	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
4371 	if (retval)
4372 		goto error;
4373 
4374 	retval = device_add(dev);
4375 	if (retval)
4376 		goto error;
4377 
4378 	return dev;
4379 
4380 error:
4381 	put_device(dev);
4382 	return ERR_PTR(retval);
4383 }
4384 
4385 /**
4386  * device_create - creates a device and registers it with sysfs
4387  * @class: pointer to the struct class that this device should be registered to
4388  * @parent: pointer to the parent struct device of this new device, if any
4389  * @devt: the dev_t for the char device to be added
4390  * @drvdata: the data to be added to the device for callbacks
4391  * @fmt: string for the device's name
4392  *
4393  * This function can be used by char device classes.  A struct device
4394  * will be created in sysfs, registered to the specified class.
4395  *
4396  * A "dev" file will be created, showing the dev_t for the device, if
4397  * the dev_t is not 0,0.
4398  * If a pointer to a parent struct device is passed in, the newly created
4399  * struct device will be a child of that device in sysfs.
4400  * The pointer to the struct device will be returned from the call.
4401  * Any further sysfs files that might be required can be created using this
4402  * pointer.
4403  *
4404  * Returns &struct device pointer on success, or ERR_PTR() on error.
4405  */
4406 struct device *device_create(const struct class *class, struct device *parent,
4407 			     dev_t devt, void *drvdata, const char *fmt, ...)
4408 {
4409 	va_list vargs;
4410 	struct device *dev;
4411 
4412 	va_start(vargs, fmt);
4413 	dev = device_create_groups_vargs(class, parent, devt, drvdata, NULL,
4414 					  fmt, vargs);
4415 	va_end(vargs);
4416 	return dev;
4417 }
4418 EXPORT_SYMBOL_GPL(device_create);
4419 
4420 /**
4421  * device_create_with_groups - creates a device and registers it with sysfs
4422  * @class: pointer to the struct class that this device should be registered to
4423  * @parent: pointer to the parent struct device of this new device, if any
4424  * @devt: the dev_t for the char device to be added
4425  * @drvdata: the data to be added to the device for callbacks
4426  * @groups: NULL-terminated list of attribute groups to be created
4427  * @fmt: string for the device's name
4428  *
4429  * This function can be used by char device classes.  A struct device
4430  * will be created in sysfs, registered to the specified class.
4431  * Additional attributes specified in the groups parameter will also
4432  * be created automatically.
4433  *
4434  * A "dev" file will be created, showing the dev_t for the device, if
4435  * the dev_t is not 0,0.
4436  * If a pointer to a parent struct device is passed in, the newly created
4437  * struct device will be a child of that device in sysfs.
4438  * The pointer to the struct device will be returned from the call.
4439  * Any further sysfs files that might be required can be created using this
4440  * pointer.
4441  *
4442  * Returns &struct device pointer on success, or ERR_PTR() on error.
4443  */
4444 struct device *device_create_with_groups(const struct class *class,
4445 					 struct device *parent, dev_t devt,
4446 					 void *drvdata,
4447 					 const struct attribute_group **groups,
4448 					 const char *fmt, ...)
4449 {
4450 	va_list vargs;
4451 	struct device *dev;
4452 
4453 	va_start(vargs, fmt);
4454 	dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
4455 					 fmt, vargs);
4456 	va_end(vargs);
4457 	return dev;
4458 }
4459 EXPORT_SYMBOL_GPL(device_create_with_groups);
4460 
4461 /**
4462  * device_destroy - removes a device that was created with device_create()
4463  * @class: pointer to the struct class that this device was registered with
4464  * @devt: the dev_t of the device that was previously registered
4465  *
4466  * This call unregisters and cleans up a device that was created with a
4467  * call to device_create().
4468  */
4469 void device_destroy(const struct class *class, dev_t devt)
4470 {
4471 	struct device *dev;
4472 
4473 	dev = class_find_device_by_devt(class, devt);
4474 	if (dev) {
4475 		put_device(dev);
4476 		device_unregister(dev);
4477 	}
4478 }
4479 EXPORT_SYMBOL_GPL(device_destroy);
4480 
4481 /**
4482  * device_rename - renames a device
4483  * @dev: the pointer to the struct device to be renamed
4484  * @new_name: the new name of the device
4485  *
4486  * It is the responsibility of the caller to provide mutual
4487  * exclusion between two different calls of device_rename
4488  * on the same device to ensure that new_name is valid and
4489  * won't conflict with other devices.
4490  *
4491  * Note: given that some subsystems (networking and infiniband) use this
4492  * function, with no immediate plans for this to change, we cannot assume or
4493  * require that this function not be called at all.
4494  *
4495  * However, if you're writing new code, do not call this function. The following
4496  * text from Kay Sievers offers some insight:
4497  *
4498  * Renaming devices is racy at many levels, symlinks and other stuff are not
4499  * replaced atomically, and you get a "move" uevent, but it's not easy to
4500  * connect the event to the old and new device. Device nodes are not renamed at
4501  * all, there isn't even support for that in the kernel now.
4502  *
4503  * In the meantime, during renaming, your target name might be taken by another
4504  * driver, creating conflicts. Or the old name is taken directly after you
4505  * renamed it -- then you get events for the same DEVPATH, before you even see
4506  * the "move" event. It's just a mess, and nothing new should ever rely on
4507  * kernel device renaming. Besides that, it's not even implemented now for
4508  * other things than (driver-core wise very simple) network devices.
4509  *
4510  * Make up a "real" name in the driver before you register anything, or add
4511  * some other attributes for userspace to find the device, or use udev to add
4512  * symlinks -- but never rename kernel devices later, it's a complete mess. We
4513  * don't even want to get into that and try to implement the missing pieces in
4514  * the core. We really have other pieces to fix in the driver core mess. :)
4515  */
4516 int device_rename(struct device *dev, const char *new_name)
4517 {
4518 	struct kobject *kobj = &dev->kobj;
4519 	char *old_device_name = NULL;
4520 	int error;
4521 
4522 	dev = get_device(dev);
4523 	if (!dev)
4524 		return -EINVAL;
4525 
4526 	dev_dbg(dev, "renaming to %s\n", new_name);
4527 
4528 	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
4529 	if (!old_device_name) {
4530 		error = -ENOMEM;
4531 		goto out;
4532 	}
4533 
4534 	if (dev->class) {
4535 		struct subsys_private *sp = class_to_subsys(dev->class);
4536 
4537 		if (!sp) {
4538 			error = -EINVAL;
4539 			goto out;
4540 		}
4541 
4542 		error = sysfs_rename_link_ns(&sp->subsys.kobj, kobj, old_device_name,
4543 					     new_name, kobject_namespace(kobj));
4544 		subsys_put(sp);
4545 		if (error)
4546 			goto out;
4547 	}
4548 
4549 	error = kobject_rename(kobj, new_name);
4550 	if (error)
4551 		goto out;
4552 
4553 out:
4554 	put_device(dev);
4555 
4556 	kfree(old_device_name);
4557 
4558 	return error;
4559 }
4560 EXPORT_SYMBOL_GPL(device_rename);
4561 
4562 static int device_move_class_links(struct device *dev,
4563 				   struct device *old_parent,
4564 				   struct device *new_parent)
4565 {
4566 	int error = 0;
4567 
4568 	if (old_parent)
4569 		sysfs_remove_link(&dev->kobj, "device");
4570 	if (new_parent)
4571 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
4572 					  "device");
4573 	return error;
4574 }
4575 
4576 /**
4577  * device_move - moves a device to a new parent
4578  * @dev: the pointer to the struct device to be moved
4579  * @new_parent: the new parent of the device (can be NULL)
4580  * @dpm_order: how to reorder the dpm_list
4581  */
4582 int device_move(struct device *dev, struct device *new_parent,
4583 		enum dpm_order dpm_order)
4584 {
4585 	int error;
4586 	struct device *old_parent;
4587 	struct kobject *new_parent_kobj;
4588 
4589 	dev = get_device(dev);
4590 	if (!dev)
4591 		return -EINVAL;
4592 
4593 	device_pm_lock();
4594 	new_parent = get_device(new_parent);
4595 	new_parent_kobj = get_device_parent(dev, new_parent);
4596 	if (IS_ERR(new_parent_kobj)) {
4597 		error = PTR_ERR(new_parent_kobj);
4598 		put_device(new_parent);
4599 		goto out;
4600 	}
4601 
4602 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
4603 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
4604 	error = kobject_move(&dev->kobj, new_parent_kobj);
4605 	if (error) {
4606 		cleanup_glue_dir(dev, new_parent_kobj);
4607 		put_device(new_parent);
4608 		goto out;
4609 	}
4610 	old_parent = dev->parent;
4611 	dev->parent = new_parent;
4612 	if (old_parent)
4613 		klist_remove(&dev->p->knode_parent);
4614 	if (new_parent) {
4615 		klist_add_tail(&dev->p->knode_parent,
4616 			       &new_parent->p->klist_children);
4617 		set_dev_node(dev, dev_to_node(new_parent));
4618 	}
4619 
4620 	if (dev->class) {
4621 		error = device_move_class_links(dev, old_parent, new_parent);
4622 		if (error) {
4623 			/* We ignore errors on cleanup since we're hosed anyway... */
4624 			device_move_class_links(dev, new_parent, old_parent);
4625 			if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
4626 				if (new_parent)
4627 					klist_remove(&dev->p->knode_parent);
4628 				dev->parent = old_parent;
4629 				if (old_parent) {
4630 					klist_add_tail(&dev->p->knode_parent,
4631 						       &old_parent->p->klist_children);
4632 					set_dev_node(dev, dev_to_node(old_parent));
4633 				}
4634 			}
4635 			cleanup_glue_dir(dev, new_parent_kobj);
4636 			put_device(new_parent);
4637 			goto out;
4638 		}
4639 	}
4640 	switch (dpm_order) {
4641 	case DPM_ORDER_NONE:
4642 		break;
4643 	case DPM_ORDER_DEV_AFTER_PARENT:
4644 		device_pm_move_after(dev, new_parent);
4645 		devices_kset_move_after(dev, new_parent);
4646 		break;
4647 	case DPM_ORDER_PARENT_BEFORE_DEV:
4648 		device_pm_move_before(new_parent, dev);
4649 		devices_kset_move_before(new_parent, dev);
4650 		break;
4651 	case DPM_ORDER_DEV_LAST:
4652 		device_pm_move_last(dev);
4653 		devices_kset_move_last(dev);
4654 		break;
4655 	}
4656 
4657 	put_device(old_parent);
4658 out:
4659 	device_pm_unlock();
4660 	put_device(dev);
4661 	return error;
4662 }
4663 EXPORT_SYMBOL_GPL(device_move);
4664 
4665 static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
4666 				     kgid_t kgid)
4667 {
4668 	struct kobject *kobj = &dev->kobj;
4669 	const struct class *class = dev->class;
4670 	const struct device_type *type = dev->type;
4671 	int error;
4672 
4673 	if (class) {
4674 		/*
4675 		 * Change the device groups of the device class for @dev to
4676 		 * @kuid/@kgid.
4677 		 */
4678 		error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
4679 						  kgid);
4680 		if (error)
4681 			return error;
4682 	}
4683 
4684 	if (type) {
4685 		/*
4686 		 * Change the device groups of the device type for @dev to
4687 		 * @kuid/@kgid.
4688 		 */
4689 		error = sysfs_groups_change_owner(kobj, type->groups, kuid,
4690 						  kgid);
4691 		if (error)
4692 			return error;
4693 	}
4694 
4695 	/* Change the device groups of @dev to @kuid/@kgid. */
4696 	error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
4697 	if (error)
4698 		return error;
4699 
4700 	if (device_supports_offline(dev) && !dev->offline_disabled) {
4701 		/* Change online device attributes of @dev to @kuid/@kgid. */
4702 		error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
4703 						kuid, kgid);
4704 		if (error)
4705 			return error;
4706 	}
4707 
4708 	return 0;
4709 }
4710 
4711 /**
4712  * device_change_owner - change the owner of an existing device.
4713  * @dev: device.
4714  * @kuid: new owner's kuid
4715  * @kgid: new owner's kgid
4716  *
4717  * This changes the owner of @dev and its corresponding sysfs entries to
4718  * @kuid/@kgid. This function closely mirrors how @dev was added via driver
4719  * core.
4720  *
4721  * Returns 0 on success or error code on failure.
4722  */
4723 int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
4724 {
4725 	int error;
4726 	struct kobject *kobj = &dev->kobj;
4727 	struct subsys_private *sp;
4728 
4729 	dev = get_device(dev);
4730 	if (!dev)
4731 		return -EINVAL;
4732 
4733 	/*
4734 	 * Change the kobject and the default attributes and groups of the
4735 	 * ktype associated with it to @kuid/@kgid.
4736 	 */
4737 	error = sysfs_change_owner(kobj, kuid, kgid);
4738 	if (error)
4739 		goto out;
4740 
4741 	/*
4742 	 * Change the uevent file for @dev to the new owner. The uevent file
4743 	 * was created in a separate step when @dev got added and we mirror
4744 	 * that step here.
4745 	 */
4746 	error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
4747 					kgid);
4748 	if (error)
4749 		goto out;
4750 
4751 	/*
4752 	 * Change the device groups, the device groups associated with the
4753 	 * device class, and the groups associated with the device type of @dev
4754 	 * to @kuid/@kgid.
4755 	 */
4756 	error = device_attrs_change_owner(dev, kuid, kgid);
4757 	if (error)
4758 		goto out;
4759 
4760 	error = dpm_sysfs_change_owner(dev, kuid, kgid);
4761 	if (error)
4762 		goto out;
4763 
4764 	/*
4765 	 * Change the owner of the symlink located in the class directory of
4766 	 * the device class associated with @dev which points to the actual
4767 	 * directory entry for @dev to @kuid/@kgid. This ensures that the
4768 	 * symlink shows the same permissions as its target.
4769 	 */
4770 	sp = class_to_subsys(dev->class);
4771 	if (!sp) {
4772 		error = -EINVAL;
4773 		goto out;
4774 	}
4775 	error = sysfs_link_change_owner(&sp->subsys.kobj, &dev->kobj, dev_name(dev), kuid, kgid);
4776 	subsys_put(sp);
4777 
4778 out:
4779 	put_device(dev);
4780 	return error;
4781 }
4782 EXPORT_SYMBOL_GPL(device_change_owner);
4783 
4784 /**
4785  * device_shutdown - call ->shutdown() on each device to shutdown.
4786  */
4787 void device_shutdown(void)
4788 {
4789 	struct device *dev, *parent;
4790 
4791 	wait_for_device_probe();
4792 	device_block_probing();
4793 
4794 	cpufreq_suspend();
4795 
4796 	spin_lock(&devices_kset->list_lock);
4797 	/*
4798 	 * Walk the devices list backward, shutting down each in turn.
4799 	 * Beware that device unplug events may also start pulling
4800 	 * devices offline, even as the system is shutting down.
4801 	 */
4802 	while (!list_empty(&devices_kset->list)) {
4803 		dev = list_entry(devices_kset->list.prev, struct device,
4804 				kobj.entry);
4805 
4806 		/*
4807 		 * hold reference count of device's parent to
4808 		 * prevent it from being freed because parent's
4809 		 * lock is to be held
4810 		 */
4811 		parent = get_device(dev->parent);
4812 		get_device(dev);
4813 		/*
4814 		 * Make sure the device is off the kset list, in the
4815 		 * event that dev->*->shutdown() doesn't remove it.
4816 		 */
4817 		list_del_init(&dev->kobj.entry);
4818 		spin_unlock(&devices_kset->list_lock);
4819 
4820 		/* hold lock to avoid race with probe/release */
4821 		if (parent)
4822 			device_lock(parent);
4823 		device_lock(dev);
4824 
4825 		/* Don't allow any more runtime suspends */
4826 		pm_runtime_get_noresume(dev);
4827 		pm_runtime_barrier(dev);
4828 
4829 		if (dev->class && dev->class->shutdown_pre) {
4830 			if (initcall_debug)
4831 				dev_info(dev, "shutdown_pre\n");
4832 			dev->class->shutdown_pre(dev);
4833 		}
4834 		if (dev->bus && dev->bus->shutdown) {
4835 			if (initcall_debug)
4836 				dev_info(dev, "shutdown\n");
4837 			dev->bus->shutdown(dev);
4838 		} else if (dev->driver && dev->driver->shutdown) {
4839 			if (initcall_debug)
4840 				dev_info(dev, "shutdown\n");
4841 			dev->driver->shutdown(dev);
4842 		}
4843 
4844 		device_unlock(dev);
4845 		if (parent)
4846 			device_unlock(parent);
4847 
4848 		put_device(dev);
4849 		put_device(parent);
4850 
4851 		spin_lock(&devices_kset->list_lock);
4852 	}
4853 	spin_unlock(&devices_kset->list_lock);
4854 }
4855 
4856 /*
4857  * Device logging functions
4858  */
4859 
4860 #ifdef CONFIG_PRINTK
4861 static void
4862 set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
4863 {
4864 	const char *subsys;
4865 
4866 	memset(dev_info, 0, sizeof(*dev_info));
4867 
4868 	if (dev->class)
4869 		subsys = dev->class->name;
4870 	else if (dev->bus)
4871 		subsys = dev->bus->name;
4872 	else
4873 		return;
4874 
4875 	strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));
4876 
4877 	/*
4878 	 * Add device identifier DEVICE=:
4879 	 *   b12:8         block dev_t
4880 	 *   c127:3        char dev_t
4881 	 *   n8            netdev ifindex
4882 	 *   +sound:card0  subsystem:devname
4883 	 */
4884 	if (MAJOR(dev->devt)) {
4885 		char c;
4886 
4887 		if (strcmp(subsys, "block") == 0)
4888 			c = 'b';
4889 		else
4890 			c = 'c';
4891 
4892 		snprintf(dev_info->device, sizeof(dev_info->device),
4893 			 "%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
4894 	} else if (strcmp(subsys, "net") == 0) {
4895 		struct net_device *net = to_net_dev(dev);
4896 
4897 		snprintf(dev_info->device, sizeof(dev_info->device),
4898 			 "n%u", net->ifindex);
4899 	} else {
4900 		snprintf(dev_info->device, sizeof(dev_info->device),
4901 			 "+%s:%s", subsys, dev_name(dev));
4902 	}
4903 }
4904 
4905 int dev_vprintk_emit(int level, const struct device *dev,
4906 		     const char *fmt, va_list args)
4907 {
4908 	struct dev_printk_info dev_info;
4909 
4910 	set_dev_info(dev, &dev_info);
4911 
4912 	return vprintk_emit(0, level, &dev_info, fmt, args);
4913 }
4914 EXPORT_SYMBOL(dev_vprintk_emit);
4915 
4916 int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
4917 {
4918 	va_list args;
4919 	int r;
4920 
4921 	va_start(args, fmt);
4922 
4923 	r = dev_vprintk_emit(level, dev, fmt, args);
4924 
4925 	va_end(args);
4926 
4927 	return r;
4928 }
4929 EXPORT_SYMBOL(dev_printk_emit);
4930 
4931 static void __dev_printk(const char *level, const struct device *dev,
4932 			struct va_format *vaf)
4933 {
4934 	if (dev)
4935 		dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
4936 				dev_driver_string(dev), dev_name(dev), vaf);
4937 	else
4938 		printk("%s(NULL device *): %pV", level, vaf);
4939 }
4940 
4941 void _dev_printk(const char *level, const struct device *dev,
4942 		 const char *fmt, ...)
4943 {
4944 	struct va_format vaf;
4945 	va_list args;
4946 
4947 	va_start(args, fmt);
4948 
4949 	vaf.fmt = fmt;
4950 	vaf.va = &args;
4951 
4952 	__dev_printk(level, dev, &vaf);
4953 
4954 	va_end(args);
4955 }
4956 EXPORT_SYMBOL(_dev_printk);
4957 
4958 #define define_dev_printk_level(func, kern_level)		\
4959 void func(const struct device *dev, const char *fmt, ...)	\
4960 {								\
4961 	struct va_format vaf;					\
4962 	va_list args;						\
4963 								\
4964 	va_start(args, fmt);					\
4965 								\
4966 	vaf.fmt = fmt;						\
4967 	vaf.va = &args;						\
4968 								\
4969 	__dev_printk(kern_level, dev, &vaf);			\
4970 								\
4971 	va_end(args);						\
4972 }								\
4973 EXPORT_SYMBOL(func);
4974 
4975 define_dev_printk_level(_dev_emerg, KERN_EMERG);
4976 define_dev_printk_level(_dev_alert, KERN_ALERT);
4977 define_dev_printk_level(_dev_crit, KERN_CRIT);
4978 define_dev_printk_level(_dev_err, KERN_ERR);
4979 define_dev_printk_level(_dev_warn, KERN_WARNING);
4980 define_dev_printk_level(_dev_notice, KERN_NOTICE);
4981 define_dev_printk_level(_dev_info, KERN_INFO);
4982 
4983 #endif
4984 
4985 /**
4986  * dev_err_probe - probe error check and log helper
4987  * @dev: the pointer to the struct device
4988  * @err: error value to test
4989  * @fmt: printf-style format string
4990  * @...: arguments as specified in the format string
4991  *
4992  * This helper implements common pattern present in probe functions for error
4993  * checking: print debug or error message depending if the error value is
4994  * -EPROBE_DEFER and propagate error upwards.
4995  * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
4996  * checked later by reading devices_deferred debugfs attribute.
4997  * It replaces code sequence::
4998  *
4999  * 	if (err != -EPROBE_DEFER)
5000  * 		dev_err(dev, ...);
5001  * 	else
5002  * 		dev_dbg(dev, ...);
5003  * 	return err;
5004  *
5005  * with::
5006  *
5007  * 	return dev_err_probe(dev, err, ...);
5008  *
5009  * Using this helper in your probe function is totally fine even if @err is
5010  * known to never be -EPROBE_DEFER.
5011  * The benefit compared to a normal dev_err() is the standardized format
5012  * of the error code, it being emitted symbolically (i.e. you get "EAGAIN"
5013  * instead of "-35") and the fact that the error code is returned which allows
5014  * more compact error paths.
5015  *
5016  * Returns @err.
5017  */
5018 int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
5019 {
5020 	struct va_format vaf;
5021 	va_list args;
5022 
5023 	va_start(args, fmt);
5024 	vaf.fmt = fmt;
5025 	vaf.va = &args;
5026 
5027 	switch (err) {
5028 	case -EPROBE_DEFER:
5029 		device_set_deferred_probe_reason(dev, &vaf);
5030 		dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5031 		break;
5032 
5033 	case -ENOMEM:
5034 		/*
5035 		 * We don't print anything on -ENOMEM, there is already enough
5036 		 * output.
5037 		 */
5038 		break;
5039 
5040 	default:
5041 		dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5042 		break;
5043 	}
5044 
5045 	va_end(args);
5046 
5047 	return err;
5048 }
5049 EXPORT_SYMBOL_GPL(dev_err_probe);
5050 
5051 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
5052 {
5053 	return fwnode && !IS_ERR(fwnode->secondary);
5054 }
5055 
5056 /**
5057  * set_primary_fwnode - Change the primary firmware node of a given device.
5058  * @dev: Device to handle.
5059  * @fwnode: New primary firmware node of the device.
5060  *
5061  * Set the device's firmware node pointer to @fwnode, but if a secondary
5062  * firmware node of the device is present, preserve it.
5063  *
5064  * Valid fwnode cases are:
5065  *  - primary --> secondary --> -ENODEV
5066  *  - primary --> NULL
5067  *  - secondary --> -ENODEV
5068  *  - NULL
5069  */
5070 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5071 {
5072 	struct device *parent = dev->parent;
5073 	struct fwnode_handle *fn = dev->fwnode;
5074 
5075 	if (fwnode) {
5076 		if (fwnode_is_primary(fn))
5077 			fn = fn->secondary;
5078 
5079 		if (fn) {
5080 			WARN_ON(fwnode->secondary);
5081 			fwnode->secondary = fn;
5082 		}
5083 		dev->fwnode = fwnode;
5084 	} else {
5085 		if (fwnode_is_primary(fn)) {
5086 			dev->fwnode = fn->secondary;
5087 
5088 			/* Skip nullifying fn->secondary if the primary is shared */
5089 			if (parent && fn == parent->fwnode)
5090 				return;
5091 
5092 			/* Set fn->secondary = NULL, so fn remains the primary fwnode */
5093 			fn->secondary = NULL;
5094 		} else {
5095 			dev->fwnode = NULL;
5096 		}
5097 	}
5098 }
5099 EXPORT_SYMBOL_GPL(set_primary_fwnode);
5100 
5101 /**
5102  * set_secondary_fwnode - Change the secondary firmware node of a given device.
5103  * @dev: Device to handle.
5104  * @fwnode: New secondary firmware node of the device.
5105  *
5106  * If a primary firmware node of the device is present, set its secondary
5107  * pointer to @fwnode.  Otherwise, set the device's firmware node pointer to
5108  * @fwnode.
5109  */
5110 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5111 {
5112 	if (fwnode)
5113 		fwnode->secondary = ERR_PTR(-ENODEV);
5114 
5115 	if (fwnode_is_primary(dev->fwnode))
5116 		dev->fwnode->secondary = fwnode;
5117 	else
5118 		dev->fwnode = fwnode;
5119 }
5120 EXPORT_SYMBOL_GPL(set_secondary_fwnode);
5121 
5122 /**
5123  * device_set_of_node_from_dev - reuse device-tree node of another device
5124  * @dev: device whose device-tree node is being set
5125  * @dev2: device whose device-tree node is being reused
5126  *
5127  * Takes another reference to the new device-tree node after first dropping
5128  * any reference held to the old node.
5129  */
5130 void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
5131 {
5132 	of_node_put(dev->of_node);
5133 	dev->of_node = of_node_get(dev2->of_node);
5134 	dev->of_node_reused = true;
5135 }
5136 EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
5137 
5138 void device_set_node(struct device *dev, struct fwnode_handle *fwnode)
5139 {
5140 	dev->fwnode = fwnode;
5141 	dev->of_node = to_of_node(fwnode);
5142 }
5143 EXPORT_SYMBOL_GPL(device_set_node);
5144 
5145 int device_match_name(struct device *dev, const void *name)
5146 {
5147 	return sysfs_streq(dev_name(dev), name);
5148 }
5149 EXPORT_SYMBOL_GPL(device_match_name);
5150 
5151 int device_match_of_node(struct device *dev, const void *np)
5152 {
5153 	return dev->of_node == np;
5154 }
5155 EXPORT_SYMBOL_GPL(device_match_of_node);
5156 
5157 int device_match_fwnode(struct device *dev, const void *fwnode)
5158 {
5159 	return dev_fwnode(dev) == fwnode;
5160 }
5161 EXPORT_SYMBOL_GPL(device_match_fwnode);
5162 
5163 int device_match_devt(struct device *dev, const void *pdevt)
5164 {
5165 	return dev->devt == *(dev_t *)pdevt;
5166 }
5167 EXPORT_SYMBOL_GPL(device_match_devt);
5168 
5169 int device_match_acpi_dev(struct device *dev, const void *adev)
5170 {
5171 	return ACPI_COMPANION(dev) == adev;
5172 }
5173 EXPORT_SYMBOL(device_match_acpi_dev);
5174 
5175 int device_match_acpi_handle(struct device *dev, const void *handle)
5176 {
5177 	return ACPI_HANDLE(dev) == handle;
5178 }
5179 EXPORT_SYMBOL(device_match_acpi_handle);
5180 
5181 int device_match_any(struct device *dev, const void *unused)
5182 {
5183 	return 1;
5184 }
5185 EXPORT_SYMBOL_GPL(device_match_any);
5186