1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Support for dynamic device trees.
4  *
5  * On some platforms, the device tree can be manipulated at runtime.
6  * The routines in this section support adding, removing and changing
7  * device tree nodes.
8  */
9 
10 #define pr_fmt(fmt)	"OF: " fmt
11 
12 #include <linux/of.h>
13 #include <linux/spinlock.h>
14 #include <linux/slab.h>
15 #include <linux/string.h>
16 #include <linux/proc_fs.h>
17 
18 #include "of_private.h"
19 
kobj_to_device_node(struct kobject * kobj)20 static struct device_node *kobj_to_device_node(struct kobject *kobj)
21 {
22 	return container_of(kobj, struct device_node, kobj);
23 }
24 
25 /**
26  * of_node_get() - Increment refcount of a node
27  * @node:	Node to inc refcount, NULL is supported to simplify writing of
28  *		callers
29  *
30  * Return: The node with refcount incremented.
31  */
of_node_get(struct device_node * node)32 struct device_node *of_node_get(struct device_node *node)
33 {
34 	if (node)
35 		kobject_get(&node->kobj);
36 	return node;
37 }
38 EXPORT_SYMBOL(of_node_get);
39 
40 /**
41  * of_node_put() - Decrement refcount of a node
42  * @node:	Node to dec refcount, NULL is supported to simplify writing of
43  *		callers
44  */
of_node_put(struct device_node * node)45 void of_node_put(struct device_node *node)
46 {
47 	if (node)
48 		kobject_put(&node->kobj);
49 }
50 EXPORT_SYMBOL(of_node_put);
51 
52 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
53 
of_reconfig_notifier_register(struct notifier_block * nb)54 int of_reconfig_notifier_register(struct notifier_block *nb)
55 {
56 	return blocking_notifier_chain_register(&of_reconfig_chain, nb);
57 }
58 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
59 
of_reconfig_notifier_unregister(struct notifier_block * nb)60 int of_reconfig_notifier_unregister(struct notifier_block *nb)
61 {
62 	return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
63 }
64 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
65 
66 #ifdef DEBUG
67 const char *action_names[] = {
68 	[OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
69 	[OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
70 	[OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
71 	[OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
72 	[OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
73 };
74 #endif
75 
of_reconfig_notify(unsigned long action,struct of_reconfig_data * p)76 int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
77 {
78 	int rc;
79 #ifdef DEBUG
80 	struct of_reconfig_data *pr = p;
81 
82 	switch (action) {
83 	case OF_RECONFIG_ATTACH_NODE:
84 	case OF_RECONFIG_DETACH_NODE:
85 		pr_debug("notify %-15s %pOF\n", action_names[action],
86 			pr->dn);
87 		break;
88 	case OF_RECONFIG_ADD_PROPERTY:
89 	case OF_RECONFIG_REMOVE_PROPERTY:
90 	case OF_RECONFIG_UPDATE_PROPERTY:
91 		pr_debug("notify %-15s %pOF:%s\n", action_names[action],
92 			pr->dn, pr->prop->name);
93 		break;
94 
95 	}
96 #endif
97 	rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
98 	return notifier_to_errno(rc);
99 }
100 
101 /*
102  * of_reconfig_get_state_change()	- Returns new state of device
103  * @action	- action of the of notifier
104  * @arg		- argument of the of notifier
105  *
106  * Returns the new state of a device based on the notifier used.
107  *
108  * Return: 0 on device going from enabled to disabled, 1 on device
109  * going from disabled to enabled and -1 on no change.
110  */
of_reconfig_get_state_change(unsigned long action,struct of_reconfig_data * pr)111 int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
112 {
113 	struct property *prop, *old_prop = NULL;
114 	int is_status, status_state, old_status_state, prev_state, new_state;
115 
116 	/* figure out if a device should be created or destroyed */
117 	switch (action) {
118 	case OF_RECONFIG_ATTACH_NODE:
119 	case OF_RECONFIG_DETACH_NODE:
120 		prop = of_find_property(pr->dn, "status", NULL);
121 		break;
122 	case OF_RECONFIG_ADD_PROPERTY:
123 	case OF_RECONFIG_REMOVE_PROPERTY:
124 		prop = pr->prop;
125 		break;
126 	case OF_RECONFIG_UPDATE_PROPERTY:
127 		prop = pr->prop;
128 		old_prop = pr->old_prop;
129 		break;
130 	default:
131 		return OF_RECONFIG_NO_CHANGE;
132 	}
133 
134 	is_status = 0;
135 	status_state = -1;
136 	old_status_state = -1;
137 	prev_state = -1;
138 	new_state = -1;
139 
140 	if (prop && !strcmp(prop->name, "status")) {
141 		is_status = 1;
142 		status_state = !strcmp(prop->value, "okay") ||
143 			       !strcmp(prop->value, "ok");
144 		if (old_prop)
145 			old_status_state = !strcmp(old_prop->value, "okay") ||
146 					   !strcmp(old_prop->value, "ok");
147 	}
148 
149 	switch (action) {
150 	case OF_RECONFIG_ATTACH_NODE:
151 		prev_state = 0;
152 		/* -1 & 0 status either missing or okay */
153 		new_state = status_state != 0;
154 		break;
155 	case OF_RECONFIG_DETACH_NODE:
156 		/* -1 & 0 status either missing or okay */
157 		prev_state = status_state != 0;
158 		new_state = 0;
159 		break;
160 	case OF_RECONFIG_ADD_PROPERTY:
161 		if (is_status) {
162 			/* no status property -> enabled (legacy) */
163 			prev_state = 1;
164 			new_state = status_state;
165 		}
166 		break;
167 	case OF_RECONFIG_REMOVE_PROPERTY:
168 		if (is_status) {
169 			prev_state = status_state;
170 			/* no status property -> enabled (legacy) */
171 			new_state = 1;
172 		}
173 		break;
174 	case OF_RECONFIG_UPDATE_PROPERTY:
175 		if (is_status) {
176 			prev_state = old_status_state != 0;
177 			new_state = status_state != 0;
178 		}
179 		break;
180 	}
181 
182 	if (prev_state == new_state)
183 		return OF_RECONFIG_NO_CHANGE;
184 
185 	return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
186 }
187 EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
188 
of_property_notify(int action,struct device_node * np,struct property * prop,struct property * oldprop)189 int of_property_notify(int action, struct device_node *np,
190 		       struct property *prop, struct property *oldprop)
191 {
192 	struct of_reconfig_data pr;
193 
194 	/* only call notifiers if the node is attached */
195 	if (!of_node_is_attached(np))
196 		return 0;
197 
198 	pr.dn = np;
199 	pr.prop = prop;
200 	pr.old_prop = oldprop;
201 	return of_reconfig_notify(action, &pr);
202 }
203 
__of_attach_node(struct device_node * np)204 static void __of_attach_node(struct device_node *np)
205 {
206 	const __be32 *phandle;
207 	int sz;
208 
209 	if (!of_node_check_flag(np, OF_OVERLAY)) {
210 		np->name = __of_get_property(np, "name", NULL);
211 		if (!np->name)
212 			np->name = "<NULL>";
213 
214 		phandle = __of_get_property(np, "phandle", &sz);
215 		if (!phandle)
216 			phandle = __of_get_property(np, "linux,phandle", &sz);
217 		if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
218 			phandle = __of_get_property(np, "ibm,phandle", &sz);
219 		if (phandle && (sz >= 4))
220 			np->phandle = be32_to_cpup(phandle);
221 		else
222 			np->phandle = 0;
223 	}
224 
225 	np->child = NULL;
226 	np->sibling = np->parent->child;
227 	np->parent->child = np;
228 	of_node_clear_flag(np, OF_DETACHED);
229 }
230 
231 /**
232  * of_attach_node() - Plug a device node into the tree and global list.
233  * @np:		Pointer to the caller's Device Node
234  */
of_attach_node(struct device_node * np)235 int of_attach_node(struct device_node *np)
236 {
237 	struct of_reconfig_data rd;
238 	unsigned long flags;
239 
240 	memset(&rd, 0, sizeof(rd));
241 	rd.dn = np;
242 
243 	mutex_lock(&of_mutex);
244 	raw_spin_lock_irqsave(&devtree_lock, flags);
245 	__of_attach_node(np);
246 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
247 
248 	__of_attach_node_sysfs(np);
249 	mutex_unlock(&of_mutex);
250 
251 	of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
252 
253 	return 0;
254 }
255 
__of_detach_node(struct device_node * np)256 void __of_detach_node(struct device_node *np)
257 {
258 	struct device_node *parent;
259 
260 	if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
261 		return;
262 
263 	parent = np->parent;
264 	if (WARN_ON(!parent))
265 		return;
266 
267 	if (parent->child == np)
268 		parent->child = np->sibling;
269 	else {
270 		struct device_node *prevsib;
271 		for (prevsib = np->parent->child;
272 		     prevsib->sibling != np;
273 		     prevsib = prevsib->sibling)
274 			;
275 		prevsib->sibling = np->sibling;
276 	}
277 
278 	of_node_set_flag(np, OF_DETACHED);
279 
280 	/* race with of_find_node_by_phandle() prevented by devtree_lock */
281 	__of_phandle_cache_inv_entry(np->phandle);
282 }
283 
284 /**
285  * of_detach_node() - "Unplug" a node from the device tree.
286  * @np:		Pointer to the caller's Device Node
287  */
of_detach_node(struct device_node * np)288 int of_detach_node(struct device_node *np)
289 {
290 	struct of_reconfig_data rd;
291 	unsigned long flags;
292 
293 	memset(&rd, 0, sizeof(rd));
294 	rd.dn = np;
295 
296 	mutex_lock(&of_mutex);
297 	raw_spin_lock_irqsave(&devtree_lock, flags);
298 	__of_detach_node(np);
299 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
300 
301 	__of_detach_node_sysfs(np);
302 	mutex_unlock(&of_mutex);
303 
304 	of_reconfig_notify(OF_RECONFIG_DETACH_NODE, &rd);
305 
306 	return 0;
307 }
308 EXPORT_SYMBOL_GPL(of_detach_node);
309 
property_list_free(struct property * prop_list)310 static void property_list_free(struct property *prop_list)
311 {
312 	struct property *prop, *next;
313 
314 	for (prop = prop_list; prop != NULL; prop = next) {
315 		next = prop->next;
316 		kfree(prop->name);
317 		kfree(prop->value);
318 		kfree(prop);
319 	}
320 }
321 
322 /**
323  * of_node_release() - release a dynamically allocated node
324  * @kobj: kernel object of the node to be released
325  *
326  * In of_node_put() this function is passed to kref_put() as the destructor.
327  */
of_node_release(struct kobject * kobj)328 void of_node_release(struct kobject *kobj)
329 {
330 	struct device_node *node = kobj_to_device_node(kobj);
331 
332 	/* We should never be releasing nodes that haven't been detached. */
333 	if (!of_node_check_flag(node, OF_DETACHED)) {
334 		pr_err("ERROR: Bad of_node_put() on %pOF\n", node);
335 		dump_stack();
336 		return;
337 	}
338 	if (!of_node_check_flag(node, OF_DYNAMIC))
339 		return;
340 
341 	if (of_node_check_flag(node, OF_OVERLAY)) {
342 
343 		if (!of_node_check_flag(node, OF_OVERLAY_FREE_CSET)) {
344 			/* premature refcount of zero, do not free memory */
345 			pr_err("ERROR: memory leak before free overlay changeset,  %pOF\n",
346 			       node);
347 			return;
348 		}
349 
350 		/*
351 		 * If node->properties non-empty then properties were added
352 		 * to this node either by different overlay that has not
353 		 * yet been removed, or by a non-overlay mechanism.
354 		 */
355 		if (node->properties)
356 			pr_err("ERROR: %s(), unexpected properties in %pOF\n",
357 			       __func__, node);
358 	}
359 
360 	property_list_free(node->properties);
361 	property_list_free(node->deadprops);
362 	fwnode_links_purge(of_fwnode_handle(node));
363 
364 	kfree(node->full_name);
365 	kfree(node->data);
366 	kfree(node);
367 }
368 
369 /**
370  * __of_prop_dup - Copy a property dynamically.
371  * @prop:	Property to copy
372  * @allocflags:	Allocation flags (typically pass GFP_KERNEL)
373  *
374  * Copy a property by dynamically allocating the memory of both the
375  * property structure and the property name & contents. The property's
376  * flags have the OF_DYNAMIC bit set so that we can differentiate between
377  * dynamically allocated properties and not.
378  *
379  * Return: The newly allocated property or NULL on out of memory error.
380  */
__of_prop_dup(const struct property * prop,gfp_t allocflags)381 struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
382 {
383 	struct property *new;
384 
385 	new = kzalloc(sizeof(*new), allocflags);
386 	if (!new)
387 		return NULL;
388 
389 	/*
390 	 * NOTE: There is no check for zero length value.
391 	 * In case of a boolean property, this will allocate a value
392 	 * of zero bytes. We do this to work around the use
393 	 * of of_get_property() calls on boolean values.
394 	 */
395 	new->name = kstrdup(prop->name, allocflags);
396 	new->value = kmemdup(prop->value, prop->length, allocflags);
397 	new->length = prop->length;
398 	if (!new->name || !new->value)
399 		goto err_free;
400 
401 	/* mark the property as dynamic */
402 	of_property_set_flag(new, OF_DYNAMIC);
403 
404 	return new;
405 
406  err_free:
407 	kfree(new->name);
408 	kfree(new->value);
409 	kfree(new);
410 	return NULL;
411 }
412 
413 /**
414  * __of_node_dup() - Duplicate or create an empty device node dynamically.
415  * @np:		if not NULL, contains properties to be duplicated in new node
416  * @full_name:	string value to be duplicated into new node's full_name field
417  *
418  * Create a device tree node, optionally duplicating the properties of
419  * another node.  The node data are dynamically allocated and all the node
420  * flags have the OF_DYNAMIC & OF_DETACHED bits set.
421  *
422  * Return: The newly allocated node or NULL on out of memory error.
423  */
__of_node_dup(const struct device_node * np,const char * full_name)424 struct device_node *__of_node_dup(const struct device_node *np,
425 				  const char *full_name)
426 {
427 	struct device_node *node;
428 
429 	node = kzalloc(sizeof(*node), GFP_KERNEL);
430 	if (!node)
431 		return NULL;
432 	node->full_name = kstrdup(full_name, GFP_KERNEL);
433 	if (!node->full_name) {
434 		kfree(node);
435 		return NULL;
436 	}
437 
438 	of_node_set_flag(node, OF_DYNAMIC);
439 	of_node_set_flag(node, OF_DETACHED);
440 	of_node_init(node);
441 
442 	/* Iterate over and duplicate all properties */
443 	if (np) {
444 		struct property *pp, *new_pp;
445 		for_each_property_of_node(np, pp) {
446 			new_pp = __of_prop_dup(pp, GFP_KERNEL);
447 			if (!new_pp)
448 				goto err_prop;
449 			if (__of_add_property(node, new_pp)) {
450 				kfree(new_pp->name);
451 				kfree(new_pp->value);
452 				kfree(new_pp);
453 				goto err_prop;
454 			}
455 		}
456 	}
457 	return node;
458 
459  err_prop:
460 	of_node_put(node); /* Frees the node and properties */
461 	return NULL;
462 }
463 
__of_changeset_entry_destroy(struct of_changeset_entry * ce)464 static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
465 {
466 	if (ce->action == OF_RECONFIG_ATTACH_NODE &&
467 	    of_node_check_flag(ce->np, OF_OVERLAY)) {
468 		if (kref_read(&ce->np->kobj.kref) > 1) {
469 			pr_err("ERROR: memory leak, expected refcount 1 instead of %d, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node %pOF\n",
470 			       kref_read(&ce->np->kobj.kref), ce->np);
471 		} else {
472 			of_node_set_flag(ce->np, OF_OVERLAY_FREE_CSET);
473 		}
474 	}
475 
476 	of_node_put(ce->np);
477 	list_del(&ce->node);
478 	kfree(ce);
479 }
480 
481 #ifdef DEBUG
__of_changeset_entry_dump(struct of_changeset_entry * ce)482 static void __of_changeset_entry_dump(struct of_changeset_entry *ce)
483 {
484 	switch (ce->action) {
485 	case OF_RECONFIG_ADD_PROPERTY:
486 	case OF_RECONFIG_REMOVE_PROPERTY:
487 	case OF_RECONFIG_UPDATE_PROPERTY:
488 		pr_debug("cset<%p> %-15s %pOF/%s\n", ce, action_names[ce->action],
489 			ce->np, ce->prop->name);
490 		break;
491 	case OF_RECONFIG_ATTACH_NODE:
492 	case OF_RECONFIG_DETACH_NODE:
493 		pr_debug("cset<%p> %-15s %pOF\n", ce, action_names[ce->action],
494 			ce->np);
495 		break;
496 	}
497 }
498 #else
__of_changeset_entry_dump(struct of_changeset_entry * ce)499 static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce)
500 {
501 	/* empty */
502 }
503 #endif
504 
__of_changeset_entry_invert(struct of_changeset_entry * ce,struct of_changeset_entry * rce)505 static void __of_changeset_entry_invert(struct of_changeset_entry *ce,
506 					  struct of_changeset_entry *rce)
507 {
508 	memcpy(rce, ce, sizeof(*rce));
509 
510 	switch (ce->action) {
511 	case OF_RECONFIG_ATTACH_NODE:
512 		rce->action = OF_RECONFIG_DETACH_NODE;
513 		break;
514 	case OF_RECONFIG_DETACH_NODE:
515 		rce->action = OF_RECONFIG_ATTACH_NODE;
516 		break;
517 	case OF_RECONFIG_ADD_PROPERTY:
518 		rce->action = OF_RECONFIG_REMOVE_PROPERTY;
519 		break;
520 	case OF_RECONFIG_REMOVE_PROPERTY:
521 		rce->action = OF_RECONFIG_ADD_PROPERTY;
522 		break;
523 	case OF_RECONFIG_UPDATE_PROPERTY:
524 		rce->old_prop = ce->prop;
525 		rce->prop = ce->old_prop;
526 		/* update was used but original property did not exist */
527 		if (!rce->prop) {
528 			rce->action = OF_RECONFIG_REMOVE_PROPERTY;
529 			rce->prop = ce->prop;
530 		}
531 		break;
532 	}
533 }
534 
__of_changeset_entry_notify(struct of_changeset_entry * ce,bool revert)535 static int __of_changeset_entry_notify(struct of_changeset_entry *ce,
536 		bool revert)
537 {
538 	struct of_reconfig_data rd;
539 	struct of_changeset_entry ce_inverted;
540 	int ret = 0;
541 
542 	if (revert) {
543 		__of_changeset_entry_invert(ce, &ce_inverted);
544 		ce = &ce_inverted;
545 	}
546 
547 	switch (ce->action) {
548 	case OF_RECONFIG_ATTACH_NODE:
549 	case OF_RECONFIG_DETACH_NODE:
550 		memset(&rd, 0, sizeof(rd));
551 		rd.dn = ce->np;
552 		ret = of_reconfig_notify(ce->action, &rd);
553 		break;
554 	case OF_RECONFIG_ADD_PROPERTY:
555 	case OF_RECONFIG_REMOVE_PROPERTY:
556 	case OF_RECONFIG_UPDATE_PROPERTY:
557 		ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop);
558 		break;
559 	default:
560 		pr_err("invalid devicetree changeset action: %i\n",
561 			(int)ce->action);
562 		ret = -EINVAL;
563 	}
564 
565 	if (ret)
566 		pr_err("changeset notifier error @%pOF\n", ce->np);
567 	return ret;
568 }
569 
__of_changeset_entry_apply(struct of_changeset_entry * ce)570 static int __of_changeset_entry_apply(struct of_changeset_entry *ce)
571 {
572 	struct property *old_prop, **propp;
573 	unsigned long flags;
574 	int ret = 0;
575 
576 	__of_changeset_entry_dump(ce);
577 
578 	raw_spin_lock_irqsave(&devtree_lock, flags);
579 	switch (ce->action) {
580 	case OF_RECONFIG_ATTACH_NODE:
581 		__of_attach_node(ce->np);
582 		break;
583 	case OF_RECONFIG_DETACH_NODE:
584 		__of_detach_node(ce->np);
585 		break;
586 	case OF_RECONFIG_ADD_PROPERTY:
587 		/* If the property is in deadprops then it must be removed */
588 		for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
589 			if (*propp == ce->prop) {
590 				*propp = ce->prop->next;
591 				ce->prop->next = NULL;
592 				break;
593 			}
594 		}
595 
596 		ret = __of_add_property(ce->np, ce->prop);
597 		if (ret) {
598 			pr_err("changeset: add_property failed @%pOF/%s\n",
599 				ce->np,
600 				ce->prop->name);
601 			break;
602 		}
603 		break;
604 	case OF_RECONFIG_REMOVE_PROPERTY:
605 		ret = __of_remove_property(ce->np, ce->prop);
606 		if (ret) {
607 			pr_err("changeset: remove_property failed @%pOF/%s\n",
608 				ce->np,
609 				ce->prop->name);
610 			break;
611 		}
612 		break;
613 
614 	case OF_RECONFIG_UPDATE_PROPERTY:
615 		/* If the property is in deadprops then it must be removed */
616 		for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) {
617 			if (*propp == ce->prop) {
618 				*propp = ce->prop->next;
619 				ce->prop->next = NULL;
620 				break;
621 			}
622 		}
623 
624 		ret = __of_update_property(ce->np, ce->prop, &old_prop);
625 		if (ret) {
626 			pr_err("changeset: update_property failed @%pOF/%s\n",
627 				ce->np,
628 				ce->prop->name);
629 			break;
630 		}
631 		break;
632 	default:
633 		ret = -EINVAL;
634 	}
635 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
636 
637 	if (ret)
638 		return ret;
639 
640 	switch (ce->action) {
641 	case OF_RECONFIG_ATTACH_NODE:
642 		__of_attach_node_sysfs(ce->np);
643 		break;
644 	case OF_RECONFIG_DETACH_NODE:
645 		__of_detach_node_sysfs(ce->np);
646 		break;
647 	case OF_RECONFIG_ADD_PROPERTY:
648 		/* ignore duplicate names */
649 		__of_add_property_sysfs(ce->np, ce->prop);
650 		break;
651 	case OF_RECONFIG_REMOVE_PROPERTY:
652 		__of_remove_property_sysfs(ce->np, ce->prop);
653 		break;
654 	case OF_RECONFIG_UPDATE_PROPERTY:
655 		__of_update_property_sysfs(ce->np, ce->prop, ce->old_prop);
656 		break;
657 	}
658 
659 	return 0;
660 }
661 
__of_changeset_entry_revert(struct of_changeset_entry * ce)662 static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce)
663 {
664 	struct of_changeset_entry ce_inverted;
665 
666 	__of_changeset_entry_invert(ce, &ce_inverted);
667 	return __of_changeset_entry_apply(&ce_inverted);
668 }
669 
670 /**
671  * of_changeset_init - Initialize a changeset for use
672  *
673  * @ocs:	changeset pointer
674  *
675  * Initialize a changeset structure
676  */
of_changeset_init(struct of_changeset * ocs)677 void of_changeset_init(struct of_changeset *ocs)
678 {
679 	memset(ocs, 0, sizeof(*ocs));
680 	INIT_LIST_HEAD(&ocs->entries);
681 }
682 EXPORT_SYMBOL_GPL(of_changeset_init);
683 
684 /**
685  * of_changeset_destroy - Destroy a changeset
686  *
687  * @ocs:	changeset pointer
688  *
689  * Destroys a changeset. Note that if a changeset is applied,
690  * its changes to the tree cannot be reverted.
691  */
of_changeset_destroy(struct of_changeset * ocs)692 void of_changeset_destroy(struct of_changeset *ocs)
693 {
694 	struct of_changeset_entry *ce, *cen;
695 
696 	list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node)
697 		__of_changeset_entry_destroy(ce);
698 }
699 EXPORT_SYMBOL_GPL(of_changeset_destroy);
700 
701 /*
702  * Apply the changeset entries in @ocs.
703  * If apply fails, an attempt is made to revert the entries that were
704  * successfully applied.
705  *
706  * If multiple revert errors occur then only the final revert error is reported.
707  *
708  * Returns 0 on success, a negative error value in case of an error.
709  * If a revert error occurs, it is returned in *ret_revert.
710  */
__of_changeset_apply_entries(struct of_changeset * ocs,int * ret_revert)711 int __of_changeset_apply_entries(struct of_changeset *ocs, int *ret_revert)
712 {
713 	struct of_changeset_entry *ce;
714 	int ret, ret_tmp;
715 
716 	pr_debug("changeset: applying...\n");
717 	list_for_each_entry(ce, &ocs->entries, node) {
718 		ret = __of_changeset_entry_apply(ce);
719 		if (ret) {
720 			pr_err("Error applying changeset (%d)\n", ret);
721 			list_for_each_entry_continue_reverse(ce, &ocs->entries,
722 							     node) {
723 				ret_tmp = __of_changeset_entry_revert(ce);
724 				if (ret_tmp)
725 					*ret_revert = ret_tmp;
726 			}
727 			return ret;
728 		}
729 	}
730 
731 	return 0;
732 }
733 
734 /*
735  * Returns 0 on success, a negative error value in case of an error.
736  *
737  * If multiple changeset entry notification errors occur then only the
738  * final notification error is reported.
739  */
__of_changeset_apply_notify(struct of_changeset * ocs)740 int __of_changeset_apply_notify(struct of_changeset *ocs)
741 {
742 	struct of_changeset_entry *ce;
743 	int ret = 0, ret_tmp;
744 
745 	pr_debug("changeset: emitting notifiers.\n");
746 
747 	/* drop the global lock while emitting notifiers */
748 	mutex_unlock(&of_mutex);
749 	list_for_each_entry(ce, &ocs->entries, node) {
750 		ret_tmp = __of_changeset_entry_notify(ce, 0);
751 		if (ret_tmp)
752 			ret = ret_tmp;
753 	}
754 	mutex_lock(&of_mutex);
755 	pr_debug("changeset: notifiers sent.\n");
756 
757 	return ret;
758 }
759 
760 /*
761  * Returns 0 on success, a negative error value in case of an error.
762  *
763  * If a changeset entry apply fails, an attempt is made to revert any
764  * previous entries in the changeset.  If any of the reverts fails,
765  * that failure is not reported.  Thus the state of the device tree
766  * is unknown if an apply error occurs.
767  */
__of_changeset_apply(struct of_changeset * ocs)768 static int __of_changeset_apply(struct of_changeset *ocs)
769 {
770 	int ret, ret_revert = 0;
771 
772 	ret = __of_changeset_apply_entries(ocs, &ret_revert);
773 	if (!ret)
774 		ret = __of_changeset_apply_notify(ocs);
775 
776 	return ret;
777 }
778 
779 /**
780  * of_changeset_apply - Applies a changeset
781  *
782  * @ocs:	changeset pointer
783  *
784  * Applies a changeset to the live tree.
785  * Any side-effects of live tree state changes are applied here on
786  * success, like creation/destruction of devices and side-effects
787  * like creation of sysfs properties and directories.
788  *
789  * Return: 0 on success, a negative error value in case of an error.
790  * On error the partially applied effects are reverted.
791  */
of_changeset_apply(struct of_changeset * ocs)792 int of_changeset_apply(struct of_changeset *ocs)
793 {
794 	int ret;
795 
796 	mutex_lock(&of_mutex);
797 	ret = __of_changeset_apply(ocs);
798 	mutex_unlock(&of_mutex);
799 
800 	return ret;
801 }
802 EXPORT_SYMBOL_GPL(of_changeset_apply);
803 
804 /*
805  * Revert the changeset entries in @ocs.
806  * If revert fails, an attempt is made to re-apply the entries that were
807  * successfully removed.
808  *
809  * If multiple re-apply errors occur then only the final apply error is
810  * reported.
811  *
812  * Returns 0 on success, a negative error value in case of an error.
813  * If an apply error occurs, it is returned in *ret_apply.
814  */
__of_changeset_revert_entries(struct of_changeset * ocs,int * ret_apply)815 int __of_changeset_revert_entries(struct of_changeset *ocs, int *ret_apply)
816 {
817 	struct of_changeset_entry *ce;
818 	int ret, ret_tmp;
819 
820 	pr_debug("changeset: reverting...\n");
821 	list_for_each_entry_reverse(ce, &ocs->entries, node) {
822 		ret = __of_changeset_entry_revert(ce);
823 		if (ret) {
824 			pr_err("Error reverting changeset (%d)\n", ret);
825 			list_for_each_entry_continue(ce, &ocs->entries, node) {
826 				ret_tmp = __of_changeset_entry_apply(ce);
827 				if (ret_tmp)
828 					*ret_apply = ret_tmp;
829 			}
830 			return ret;
831 		}
832 	}
833 
834 	return 0;
835 }
836 
837 /*
838  * If multiple changeset entry notification errors occur then only the
839  * final notification error is reported.
840  */
__of_changeset_revert_notify(struct of_changeset * ocs)841 int __of_changeset_revert_notify(struct of_changeset *ocs)
842 {
843 	struct of_changeset_entry *ce;
844 	int ret = 0, ret_tmp;
845 
846 	pr_debug("changeset: emitting notifiers.\n");
847 
848 	/* drop the global lock while emitting notifiers */
849 	mutex_unlock(&of_mutex);
850 	list_for_each_entry_reverse(ce, &ocs->entries, node) {
851 		ret_tmp = __of_changeset_entry_notify(ce, 1);
852 		if (ret_tmp)
853 			ret = ret_tmp;
854 	}
855 	mutex_lock(&of_mutex);
856 	pr_debug("changeset: notifiers sent.\n");
857 
858 	return ret;
859 }
860 
__of_changeset_revert(struct of_changeset * ocs)861 static int __of_changeset_revert(struct of_changeset *ocs)
862 {
863 	int ret, ret_reply;
864 
865 	ret_reply = 0;
866 	ret = __of_changeset_revert_entries(ocs, &ret_reply);
867 
868 	if (!ret)
869 		ret = __of_changeset_revert_notify(ocs);
870 
871 	return ret;
872 }
873 
874 /**
875  * of_changeset_revert - Reverts an applied changeset
876  *
877  * @ocs:	changeset pointer
878  *
879  * Reverts a changeset returning the state of the tree to what it
880  * was before the application.
881  * Any side-effects like creation/destruction of devices and
882  * removal of sysfs properties and directories are applied.
883  *
884  * Return: 0 on success, a negative error value in case of an error.
885  */
of_changeset_revert(struct of_changeset * ocs)886 int of_changeset_revert(struct of_changeset *ocs)
887 {
888 	int ret;
889 
890 	mutex_lock(&of_mutex);
891 	ret = __of_changeset_revert(ocs);
892 	mutex_unlock(&of_mutex);
893 
894 	return ret;
895 }
896 EXPORT_SYMBOL_GPL(of_changeset_revert);
897 
898 /**
899  * of_changeset_action - Add an action to the tail of the changeset list
900  *
901  * @ocs:	changeset pointer
902  * @action:	action to perform
903  * @np:		Pointer to device node
904  * @prop:	Pointer to property
905  *
906  * On action being one of:
907  * + OF_RECONFIG_ATTACH_NODE
908  * + OF_RECONFIG_DETACH_NODE,
909  * + OF_RECONFIG_ADD_PROPERTY
910  * + OF_RECONFIG_REMOVE_PROPERTY,
911  * + OF_RECONFIG_UPDATE_PROPERTY
912  *
913  * Return: 0 on success, a negative error value in case of an error.
914  */
of_changeset_action(struct of_changeset * ocs,unsigned long action,struct device_node * np,struct property * prop)915 int of_changeset_action(struct of_changeset *ocs, unsigned long action,
916 		struct device_node *np, struct property *prop)
917 {
918 	struct of_changeset_entry *ce;
919 
920 	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
921 	if (!ce)
922 		return -ENOMEM;
923 
924 	/* get a reference to the node */
925 	ce->action = action;
926 	ce->np = of_node_get(np);
927 	ce->prop = prop;
928 
929 	if (action == OF_RECONFIG_UPDATE_PROPERTY && prop)
930 		ce->old_prop = of_find_property(np, prop->name, NULL);
931 
932 	/* add it to the list */
933 	list_add_tail(&ce->node, &ocs->entries);
934 	return 0;
935 }
936 EXPORT_SYMBOL_GPL(of_changeset_action);
937