xref: /openbmc/linux/drivers/of/dynamic.c (revision 4f205687)
1 /*
2  * Support for dynamic device trees.
3  *
4  * On some platforms, the device tree can be manipulated at runtime.
5  * The routines in this section support adding, removing and changing
6  * device tree nodes.
7  */
8 
9 #include <linux/of.h>
10 #include <linux/spinlock.h>
11 #include <linux/slab.h>
12 #include <linux/string.h>
13 #include <linux/proc_fs.h>
14 
15 #include "of_private.h"
16 
17 /**
18  * of_node_get() - Increment refcount of a node
19  * @node:	Node to inc refcount, NULL is supported to simplify writing of
20  *		callers
21  *
22  * Returns node.
23  */
24 struct device_node *of_node_get(struct device_node *node)
25 {
26 	if (node)
27 		kobject_get(&node->kobj);
28 	return node;
29 }
30 EXPORT_SYMBOL(of_node_get);
31 
32 /**
33  * of_node_put() - Decrement refcount of a node
34  * @node:	Node to dec refcount, NULL is supported to simplify writing of
35  *		callers
36  */
37 void of_node_put(struct device_node *node)
38 {
39 	if (node)
40 		kobject_put(&node->kobj);
41 }
42 EXPORT_SYMBOL(of_node_put);
43 
44 void __of_detach_node_sysfs(struct device_node *np)
45 {
46 	struct property *pp;
47 
48 	if (!IS_ENABLED(CONFIG_SYSFS))
49 		return;
50 
51 	BUG_ON(!of_node_is_initialized(np));
52 	if (!of_kset)
53 		return;
54 
55 	/* only remove properties if on sysfs */
56 	if (of_node_is_attached(np)) {
57 		for_each_property_of_node(np, pp)
58 			sysfs_remove_bin_file(&np->kobj, &pp->attr);
59 		kobject_del(&np->kobj);
60 	}
61 
62 	/* finally remove the kobj_init ref */
63 	of_node_put(np);
64 }
65 
66 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
67 
68 int of_reconfig_notifier_register(struct notifier_block *nb)
69 {
70 	return blocking_notifier_chain_register(&of_reconfig_chain, nb);
71 }
72 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
73 
74 int of_reconfig_notifier_unregister(struct notifier_block *nb)
75 {
76 	return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
77 }
78 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
79 
80 #ifdef DEBUG
81 const char *action_names[] = {
82 	[OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
83 	[OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
84 	[OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
85 	[OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
86 	[OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
87 };
88 #endif
89 
90 int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
91 {
92 	int rc;
93 #ifdef DEBUG
94 	struct of_reconfig_data *pr = p;
95 
96 	switch (action) {
97 	case OF_RECONFIG_ATTACH_NODE:
98 	case OF_RECONFIG_DETACH_NODE:
99 		pr_debug("of/notify %-15s %s\n", action_names[action],
100 			pr->dn->full_name);
101 		break;
102 	case OF_RECONFIG_ADD_PROPERTY:
103 	case OF_RECONFIG_REMOVE_PROPERTY:
104 	case OF_RECONFIG_UPDATE_PROPERTY:
105 		pr_debug("of/notify %-15s %s:%s\n", action_names[action],
106 			pr->dn->full_name, pr->prop->name);
107 		break;
108 
109 	}
110 #endif
111 	rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
112 	return notifier_to_errno(rc);
113 }
114 
115 /*
116  * of_reconfig_get_state_change()	- Returns new state of device
117  * @action	- action of the of notifier
118  * @arg		- argument of the of notifier
119  *
120  * Returns the new state of a device based on the notifier used.
121  * Returns 0 on device going from enabled to disabled, 1 on device
122  * going from disabled to enabled and -1 on no change.
123  */
124 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
125 {
126 	struct property *prop, *old_prop = NULL;
127 	int is_status, status_state, old_status_state, prev_state, new_state;
128 
129 	/* figure out if a device should be created or destroyed */
130 	switch (action) {
131 	case OF_RECONFIG_ATTACH_NODE:
132 	case OF_RECONFIG_DETACH_NODE:
133 		prop = of_find_property(pr->dn, "status", NULL);
134 		break;
135 	case OF_RECONFIG_ADD_PROPERTY:
136 	case OF_RECONFIG_REMOVE_PROPERTY:
137 		prop = pr->prop;
138 		break;
139 	case OF_RECONFIG_UPDATE_PROPERTY:
140 		prop = pr->prop;
141 		old_prop = pr->old_prop;
142 		break;
143 	default:
144 		return OF_RECONFIG_NO_CHANGE;
145 	}
146 
147 	is_status = 0;
148 	status_state = -1;
149 	old_status_state = -1;
150 	prev_state = -1;
151 	new_state = -1;
152 
153 	if (prop && !strcmp(prop->name, "status")) {
154 		is_status = 1;
155 		status_state = !strcmp(prop->value, "okay") ||
156 			       !strcmp(prop->value, "ok");
157 		if (old_prop)
158 			old_status_state = !strcmp(old_prop->value, "okay") ||
159 					   !strcmp(old_prop->value, "ok");
160 	}
161 
162 	switch (action) {
163 	case OF_RECONFIG_ATTACH_NODE:
164 		prev_state = 0;
165 		/* -1 & 0 status either missing or okay */
166 		new_state = status_state != 0;
167 		break;
168 	case OF_RECONFIG_DETACH_NODE:
169 		/* -1 & 0 status either missing or okay */
170 		prev_state = status_state != 0;
171 		new_state = 0;
172 		break;
173 	case OF_RECONFIG_ADD_PROPERTY:
174 		if (is_status) {
175 			/* no status property -> enabled (legacy) */
176 			prev_state = 1;
177 			new_state = status_state;
178 		}
179 		break;
180 	case OF_RECONFIG_REMOVE_PROPERTY:
181 		if (is_status) {
182 			prev_state = status_state;
183 			/* no status property -> enabled (legacy) */
184 			new_state = 1;
185 		}
186 		break;
187 	case OF_RECONFIG_UPDATE_PROPERTY:
188 		if (is_status) {
189 			prev_state = old_status_state != 0;
190 			new_state = status_state != 0;
191 		}
192 		break;
193 	}
194 
195 	if (prev_state == new_state)
196 		return OF_RECONFIG_NO_CHANGE;
197 
198 	return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
199 }
200 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
201 
202 int of_property_notify(int action, struct device_node *np,
203 		       struct property *prop, struct property *oldprop)
204 {
205 	struct of_reconfig_data pr;
206 
207 	/* only call notifiers if the node is attached */
208 	if (!of_node_is_attached(np))
209 		return 0;
210 
211 	pr.dn = np;
212 	pr.prop = prop;
213 	pr.old_prop = oldprop;
214 	return of_reconfig_notify(action, &pr);
215 }
216 
217 void __of_attach_node(struct device_node *np)
218 {
219 	const __be32 *phandle;
220 	int sz;
221 
222 	np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
223 	np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
224 
225 	phandle = __of_get_property(np, "phandle", &sz);
226 	if (!phandle)
227 		phandle = __of_get_property(np, "linux,phandle", &sz);
228 	if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
229 		phandle = __of_get_property(np, "ibm,phandle", &sz);
230 	np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
231 
232 	np->child = NULL;
233 	np->sibling = np->parent->child;
234 	np->parent->child = np;
235 	of_node_clear_flag(np, OF_DETACHED);
236 }
237 
238 /**
239  * of_attach_node() - Plug a device node into the tree and global list.
240  */
241 int of_attach_node(struct device_node *np)
242 {
243 	struct of_reconfig_data rd;
244 	unsigned long flags;
245 
246 	memset(&rd, 0, sizeof(rd));
247 	rd.dn = np;
248 
249 	mutex_lock(&of_mutex);
250 	raw_spin_lock_irqsave(&devtree_lock, flags);
251 	__of_attach_node(np);
252 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
253 
254 	__of_attach_node_sysfs(np);
255 	mutex_unlock(&of_mutex);
256 
257 	of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
258 
259 	return 0;
260 }
261 
262 void __of_detach_node(struct device_node *np)
263 {
264 	struct device_node *parent;
265 
266 	if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
267 		return;
268 
269 	parent = np->parent;
270 	if (WARN_ON(!parent))
271 		return;
272 
273 	if (parent->child == np)
274 		parent->child = np->sibling;
275 	else {
276 		struct device_node *prevsib;
277 		for (prevsib = np->parent->child;
278 		     prevsib->sibling != np;
279 		     prevsib = prevsib->sibling)
280 			;
281 		prevsib->sibling = np->sibling;
282 	}
283 
284 	of_node_set_flag(np, OF_DETACHED);
285 }
286 
287 /**
288  * of_detach_node() - "Unplug" a node from the device tree.
289  *
290  * The caller must hold a reference to the node.  The memory associated with
291  * the node is not freed until its refcount goes to zero.
292  */
293 int of_detach_node(struct device_node *np)
294 {
295 	struct of_reconfig_data rd;
296 	unsigned long flags;
297 	int rc = 0;
298 
299 	memset(&rd, 0, sizeof(rd));
300 	rd.dn = np;
301 
302 	mutex_lock(&of_mutex);
303 	raw_spin_lock_irqsave(&devtree_lock, flags);
304 	__of_detach_node(np);
305 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
306 
307 	__of_detach_node_sysfs(np);
308 	mutex_unlock(&of_mutex);
309 
310 	of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
311 
312 	return rc;
313 }
314 EXPORT_SYMBOL_GPL(of_detach_node);
315 
316 /**
317  * of_node_release() - release a dynamically allocated node
318  * @kref: kref element of the node to be released
319  *
320  * In of_node_put() this function is passed to kref_put() as the destructor.
321  */
322 void of_node_release(struct kobject *kobj)
323 {
324 	struct device_node *node = kobj_to_device_node(kobj);
325 	struct property *prop = node->properties;
326 
327 	/* We should never be releasing nodes that haven't been detached. */
328 	if (!of_node_check_flag(node, OF_DETACHED)) {
329 		pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
330 		dump_stack();
331 		return;
332 	}
333 
334 	if (!of_node_check_flag(node, OF_DYNAMIC))
335 		return;
336 
337 	while (prop) {
338 		struct property *next = prop->next;
339 		kfree(prop->name);
340 		kfree(prop->value);
341 		kfree(prop);
342 		prop = next;
343 
344 		if (!prop) {
345 			prop = node->deadprops;
346 			node->deadprops = NULL;
347 		}
348 	}
349 	kfree(node->full_name);
350 	kfree(node->data);
351 	kfree(node);
352 }
353 
354 /**
355  * __of_prop_dup - Copy a property dynamically.
356  * @prop:	Property to copy
357  * @allocflags:	Allocation flags (typically pass GFP_KERNEL)
358  *
359  * Copy a property by dynamically allocating the memory of both the
360  * property structure and the property name & contents. The property's
361  * flags have the OF_DYNAMIC bit set so that we can differentiate between
362  * dynamically allocated properties and not.
363  * Returns the newly allocated property or NULL on out of memory error.
364  */
365 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
366 {
367 	struct property *new;
368 
369 	new = kzalloc(sizeof(*new), allocflags);
370 	if (!new)
371 		return NULL;
372 
373 	/*
374 	 * NOTE: There is no check for zero length value.
375 	 * In case of a boolean property, this will allocate a value
376 	 * of zero bytes. We do this to work around the use
377 	 * of of_get_property() calls on boolean values.
378 	 */
379 	new->name = kstrdup(prop->name, allocflags);
380 	new->value = kmemdup(prop->value, prop->length, allocflags);
381 	new->length = prop->length;
382 	if (!new->name || !new->value)
383 		goto err_free;
384 
385 	/* mark the property as dynamic */
386 	of_property_set_flag(new, OF_DYNAMIC);
387 
388 	return new;
389 
390  err_free:
391 	kfree(new->name);
392 	kfree(new->value);
393 	kfree(new);
394 	return NULL;
395 }
396 
397 /**
398  * __of_node_dup() - Duplicate or create an empty device node dynamically.
399  * @fmt: Format string (plus vargs) for new full name of the device node
400  *
401  * Create an device tree node, either by duplicating an empty node or by allocating
402  * an empty one suitable for further modification.  The node data are
403  * dynamically allocated and all the node flags have the OF_DYNAMIC &
404  * OF_DETACHED bits set. Returns the newly allocated node or NULL on out of
405  * memory error.
406  */
407 struct device_node *__of_node_dup(const struct device_node *np, const char *fmt, ...)
408 {
409 	va_list vargs;
410 	struct device_node *node;
411 
412 	node = kzalloc(sizeof(*node), GFP_KERNEL);
413 	if (!node)
414 		return NULL;
415 	va_start(vargs, fmt);
416 	node->full_name = kvasprintf(GFP_KERNEL, fmt, vargs);
417 	va_end(vargs);
418 	if (!node->full_name) {
419 		kfree(node);
420 		return NULL;
421 	}
422 
423 	of_node_set_flag(node, OF_DYNAMIC);
424 	of_node_set_flag(node, OF_DETACHED);
425 	of_node_init(node);
426 
427 	/* Iterate over and duplicate all properties */
428 	if (np) {
429 		struct property *pp, *new_pp;
430 		for_each_property_of_node(np, pp) {
431 			new_pp = __of_prop_dup(pp, GFP_KERNEL);
432 			if (!new_pp)
433 				goto err_prop;
434 			if (__of_add_property(node, new_pp)) {
435 				kfree(new_pp->name);
436 				kfree(new_pp->value);
437 				kfree(new_pp);
438 				goto err_prop;
439 			}
440 		}
441 	}
442 	return node;
443 
444  err_prop:
445 	of_node_put(node); /* Frees the node and properties */
446 	return NULL;
447 }
448 
449 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
450 {
451 	of_node_put(ce->np);
452 	list_del(&ce->node);
453 	kfree(ce);
454 }
455 
456 #ifdef DEBUG
457 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
458 {
459 	switch (ce->action) {
460 	case OF_RECONFIG_ADD_PROPERTY:
461 	case OF_RECONFIG_REMOVE_PROPERTY:
462 	case OF_RECONFIG_UPDATE_PROPERTY:
463 		pr_debug("of/cset<%p> %-15s %s/%s\n", ce, action_names[ce->action],
464 			ce->np->full_name, ce->prop->name);
465 		break;
466 	case OF_RECONFIG_ATTACH_NODE:
467 	case OF_RECONFIG_DETACH_NODE:
468 		pr_debug("of/cset<%p> %-15s %s\n", ce, action_names[ce->action],
469 			ce->np->full_name);
470 		break;
471 	}
472 }
473 #else
474 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
475 {
476 	/* empty */
477 }
478 #endif
479 
480 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
481 					  struct of_changeset_entry *rce)
482 {
483 	memcpy(rce, ce, sizeof(*rce));
484 
485 	switch (ce->action) {
486 	case OF_RECONFIG_ATTACH_NODE:
487 		rce->action = OF_RECONFIG_DETACH_NODE;
488 		break;
489 	case OF_RECONFIG_DETACH_NODE:
490 		rce->action = OF_RECONFIG_ATTACH_NODE;
491 		break;
492 	case OF_RECONFIG_ADD_PROPERTY:
493 		rce->action = OF_RECONFIG_REMOVE_PROPERTY;
494 		break;
495 	case OF_RECONFIG_REMOVE_PROPERTY:
496 		rce->action = OF_RECONFIG_ADD_PROPERTY;
497 		break;
498 	case OF_RECONFIG_UPDATE_PROPERTY:
499 		rce->old_prop = ce->prop;
500 		rce->prop = ce->old_prop;
501 		/* update was used but original property did not exist */
502 		if (!rce->prop) {
503 			rce->action = OF_RECONFIG_REMOVE_PROPERTY;
504 			rce->prop = ce->prop;
505 		}
506 		break;
507 	}
508 }
509 
510 static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert)
511 {
512 	struct of_reconfig_data rd;
513 	struct of_changeset_entry ce_inverted;
514 	int ret;
515 
516 	if (revert) {
517 		__of_changeset_entry_invert(ce, &ce_inverted);
518 		ce = &ce_inverted;
519 	}
520 
521 	switch (ce->action) {
522 	case OF_RECONFIG_ATTACH_NODE:
523 	case OF_RECONFIG_DETACH_NODE:
524 		memset(&rd, 0, sizeof(rd));
525 		rd.dn = ce->np;
526 		ret = of_reconfig_notify(ce->action, &rd);
527 		break;
528 	case OF_RECONFIG_ADD_PROPERTY:
529 	case OF_RECONFIG_REMOVE_PROPERTY:
530 	case OF_RECONFIG_UPDATE_PROPERTY:
531 		ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
532 		break;
533 	default:
534 		pr_err("%s: invalid devicetree changeset action: %i\n", __func__,
535 			(int)ce->action);
536 		return;
537 	}
538 
539 	if (ret)
540 		pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name);
541 }
542 
543 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
544 {
545 	struct property *old_prop, **propp;
546 	unsigned long flags;
547 	int ret = 0;
548 
549 	__of_changeset_entry_dump(ce);
550 
551 	raw_spin_lock_irqsave(&devtree_lock, flags);
552 	switch (ce->action) {
553 	case OF_RECONFIG_ATTACH_NODE:
554 		__of_attach_node(ce->np);
555 		break;
556 	case OF_RECONFIG_DETACH_NODE:
557 		__of_detach_node(ce->np);
558 		break;
559 	case OF_RECONFIG_ADD_PROPERTY:
560 		/* If the property is in deadprops then it must be removed */
561 		for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
562 			if (*propp == ce->prop) {
563 				*propp = ce->prop->next;
564 				ce->prop->next = NULL;
565 				break;
566 			}
567 		}
568 
569 		ret = __of_add_property(ce->np, ce->prop);
570 		if (ret) {
571 			pr_err("%s: add_property failed @%s/%s\n",
572 				__func__, ce->np->full_name,
573 				ce->prop->name);
574 			break;
575 		}
576 		break;
577 	case OF_RECONFIG_REMOVE_PROPERTY:
578 		ret = __of_remove_property(ce->np, ce->prop);
579 		if (ret) {
580 			pr_err("%s: remove_property failed @%s/%s\n",
581 				__func__, ce->np->full_name,
582 				ce->prop->name);
583 			break;
584 		}
585 		break;
586 
587 	case OF_RECONFIG_UPDATE_PROPERTY:
588 		/* If the property is in deadprops then it must be removed */
589 		for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
590 			if (*propp == ce->prop) {
591 				*propp = ce->prop->next;
592 				ce->prop->next = NULL;
593 				break;
594 			}
595 		}
596 
597 		ret = __of_update_property(ce->np, ce->prop, &old_prop);
598 		if (ret) {
599 			pr_err("%s: update_property failed @%s/%s\n",
600 				__func__, ce->np->full_name,
601 				ce->prop->name);
602 			break;
603 		}
604 		break;
605 	default:
606 		ret = -EINVAL;
607 	}
608 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
609 
610 	if (ret)
611 		return ret;
612 
613 	switch (ce->action) {
614 	case OF_RECONFIG_ATTACH_NODE:
615 		__of_attach_node_sysfs(ce->np);
616 		break;
617 	case OF_RECONFIG_DETACH_NODE:
618 		__of_detach_node_sysfs(ce->np);
619 		break;
620 	case OF_RECONFIG_ADD_PROPERTY:
621 		/* ignore duplicate names */
622 		__of_add_property_sysfs(ce->np, ce->prop);
623 		break;
624 	case OF_RECONFIG_REMOVE_PROPERTY:
625 		__of_remove_property_sysfs(ce->np, ce->prop);
626 		break;
627 	case OF_RECONFIG_UPDATE_PROPERTY:
628 		__of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
629 		break;
630 	}
631 
632 	return 0;
633 }
634 
635 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
636 {
637 	struct of_changeset_entry ce_inverted;
638 
639 	__of_changeset_entry_invert(ce, &ce_inverted);
640 	return __of_changeset_entry_apply(&ce_inverted);
641 }
642 
643 /**
644  * of_changeset_init - Initialize a changeset for use
645  *
646  * @ocs:	changeset pointer
647  *
648  * Initialize a changeset structure
649  */
650 void of_changeset_init(struct of_changeset *ocs)
651 {
652 	memset(ocs, 0, sizeof(*ocs));
653 	INIT_LIST_HEAD(&ocs->entries);
654 }
655 EXPORT_SYMBOL_GPL(of_changeset_init);
656 
657 /**
658  * of_changeset_destroy - Destroy a changeset
659  *
660  * @ocs:	changeset pointer
661  *
662  * Destroys a changeset. Note that if a changeset is applied,
663  * its changes to the tree cannot be reverted.
664  */
665 void of_changeset_destroy(struct of_changeset *ocs)
666 {
667 	struct of_changeset_entry *ce, *cen;
668 
669 	list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
670 		__of_changeset_entry_destroy(ce);
671 }
672 EXPORT_SYMBOL_GPL(of_changeset_destroy);
673 
674 int __of_changeset_apply(struct of_changeset *ocs)
675 {
676 	struct of_changeset_entry *ce;
677 	int ret;
678 
679 	/* perform the rest of the work */
680 	pr_debug("of_changeset: applying...\n");
681 	list_for_each_entry(ce, &ocs->entries, node) {
682 		ret = __of_changeset_entry_apply(ce);
683 		if (ret) {
684 			pr_err("%s: Error applying changeset (%d)\n", __func__, ret);
685 			list_for_each_entry_continue_reverse(ce, &ocs->entries, node)
686 				__of_changeset_entry_revert(ce);
687 			return ret;
688 		}
689 	}
690 	pr_debug("of_changeset: applied, emitting notifiers.\n");
691 
692 	/* drop the global lock while emitting notifiers */
693 	mutex_unlock(&of_mutex);
694 	list_for_each_entry(ce, &ocs->entries, node)
695 		__of_changeset_entry_notify(ce, 0);
696 	mutex_lock(&of_mutex);
697 	pr_debug("of_changeset: notifiers sent.\n");
698 
699 	return 0;
700 }
701 
702 /**
703  * of_changeset_apply - Applies a changeset
704  *
705  * @ocs:	changeset pointer
706  *
707  * Applies a changeset to the live tree.
708  * Any side-effects of live tree state changes are applied here on
709  * success, like creation/destruction of devices and side-effects
710  * like creation of sysfs properties and directories.
711  * Returns 0 on success, a negative error value in case of an error.
712  * On error the partially applied effects are reverted.
713  */
714 int of_changeset_apply(struct of_changeset *ocs)
715 {
716 	int ret;
717 
718 	mutex_lock(&of_mutex);
719 	ret = __of_changeset_apply(ocs);
720 	mutex_unlock(&of_mutex);
721 
722 	return ret;
723 }
724 EXPORT_SYMBOL_GPL(of_changeset_apply);
725 
726 int __of_changeset_revert(struct of_changeset *ocs)
727 {
728 	struct of_changeset_entry *ce;
729 	int ret;
730 
731 	pr_debug("of_changeset: reverting...\n");
732 	list_for_each_entry_reverse(ce, &ocs->entries, node) {
733 		ret = __of_changeset_entry_revert(ce);
734 		if (ret) {
735 			pr_err("%s: Error reverting changeset (%d)\n", __func__, ret);
736 			list_for_each_entry_continue(ce, &ocs->entries, node)
737 				__of_changeset_entry_apply(ce);
738 			return ret;
739 		}
740 	}
741 	pr_debug("of_changeset: reverted, emitting notifiers.\n");
742 
743 	/* drop the global lock while emitting notifiers */
744 	mutex_unlock(&of_mutex);
745 	list_for_each_entry_reverse(ce, &ocs->entries, node)
746 		__of_changeset_entry_notify(ce, 1);
747 	mutex_lock(&of_mutex);
748 	pr_debug("of_changeset: notifiers sent.\n");
749 
750 	return 0;
751 }
752 
753 /**
754  * of_changeset_revert - Reverts an applied changeset
755  *
756  * @ocs:	changeset pointer
757  *
758  * Reverts a changeset returning the state of the tree to what it
759  * was before the application.
760  * Any side-effects like creation/destruction of devices and
761  * removal of sysfs properties and directories are applied.
762  * Returns 0 on success, a negative error value in case of an error.
763  */
764 int of_changeset_revert(struct of_changeset *ocs)
765 {
766 	int ret;
767 
768 	mutex_lock(&of_mutex);
769 	ret = __of_changeset_revert(ocs);
770 	mutex_unlock(&of_mutex);
771 
772 	return ret;
773 }
774 EXPORT_SYMBOL_GPL(of_changeset_revert);
775 
776 /**
777  * of_changeset_action - Perform a changeset action
778  *
779  * @ocs:	changeset pointer
780  * @action:	action to perform
781  * @np:		Pointer to device node
782  * @prop:	Pointer to property
783  *
784  * On action being one of:
785  * + OF_RECONFIG_ATTACH_NODE
786  * + OF_RECONFIG_DETACH_NODE,
787  * + OF_RECONFIG_ADD_PROPERTY
788  * + OF_RECONFIG_REMOVE_PROPERTY,
789  * + OF_RECONFIG_UPDATE_PROPERTY
790  * Returns 0 on success, a negative error value in case of an error.
791  */
792 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
793 		struct device_node *np, struct property *prop)
794 {
795 	struct of_changeset_entry *ce;
796 
797 	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
798 	if (!ce) {
799 		pr_err("%s: Failed to allocate\n", __func__);
800 		return -ENOMEM;
801 	}
802 	/* get a reference to the node */
803 	ce->action = action;
804 	ce->np = of_node_get(np);
805 	ce->prop = prop;
806 
807 	if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
808 		ce->old_prop = of_find_property(np, prop->name, NULL);
809 
810 	/* add it to the list */
811 	list_add_tail(&ce->node, &ocs->entries);
812 	return 0;
813 }
814 EXPORT_SYMBOL_GPL(of_changeset_action);
815