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  • only in /asuswrt-rt-n18u-9.0.0.4.380.2695/release/src-rt-6.x.4708/linux/linux-2.6/drivers/of/
1/*
2 * Procedures for creating, accessing and interpreting the device tree.
3 *
4 * Paul Mackerras	August 1996.
5 * Copyright (C) 1996-2005 Paul Mackerras.
6 *
7 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
8 *    {engebret|bergner}@us.ibm.com
9 *
10 *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
11 *
12 *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
13 *  Grant Likely.
14 *
15 *      This program is free software; you can redistribute it and/or
16 *      modify it under the terms of the GNU General Public License
17 *      as published by the Free Software Foundation; either version
18 *      2 of the License, or (at your option) any later version.
19 */
20#include <linux/module.h>
21#include <linux/of.h>
22#include <linux/spinlock.h>
23#include <linux/slab.h>
24#include <linux/proc_fs.h>
25
26struct device_node *allnodes;
27struct device_node *of_chosen;
28
29/* use when traversing tree through the allnext, child, sibling,
30 * or parent members of struct device_node.
31 */
32DEFINE_RWLOCK(devtree_lock);
33
34int of_n_addr_cells(struct device_node *np)
35{
36	const int *ip;
37
38	do {
39		if (np->parent)
40			np = np->parent;
41		ip = of_get_property(np, "#address-cells", NULL);
42		if (ip)
43			return be32_to_cpup(ip);
44	} while (np->parent);
45	/* No #address-cells property for the root node */
46	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
47}
48EXPORT_SYMBOL(of_n_addr_cells);
49
50int of_n_size_cells(struct device_node *np)
51{
52	const int *ip;
53
54	do {
55		if (np->parent)
56			np = np->parent;
57		ip = of_get_property(np, "#size-cells", NULL);
58		if (ip)
59			return be32_to_cpup(ip);
60	} while (np->parent);
61	/* No #size-cells property for the root node */
62	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
63}
64EXPORT_SYMBOL(of_n_size_cells);
65
66#if !defined(CONFIG_SPARC)   /* SPARC doesn't do ref counting (yet) */
67/**
68 *	of_node_get - Increment refcount of a node
69 *	@node:	Node to inc refcount, NULL is supported to
70 *		simplify writing of callers
71 *
72 *	Returns node.
73 */
74struct device_node *of_node_get(struct device_node *node)
75{
76	if (node)
77		kref_get(&node->kref);
78	return node;
79}
80EXPORT_SYMBOL(of_node_get);
81
82static inline struct device_node *kref_to_device_node(struct kref *kref)
83{
84	return container_of(kref, struct device_node, kref);
85}
86
87/**
88 *	of_node_release - release a dynamically allocated node
89 *	@kref:  kref element of the node to be released
90 *
91 *	In of_node_put() this function is passed to kref_put()
92 *	as the destructor.
93 */
94static void of_node_release(struct kref *kref)
95{
96	struct device_node *node = kref_to_device_node(kref);
97	struct property *prop = node->properties;
98
99	/* We should never be releasing nodes that haven't been detached. */
100	if (!of_node_check_flag(node, OF_DETACHED)) {
101		pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
102		dump_stack();
103		kref_init(&node->kref);
104		return;
105	}
106
107	if (!of_node_check_flag(node, OF_DYNAMIC))
108		return;
109
110	while (prop) {
111		struct property *next = prop->next;
112		kfree(prop->name);
113		kfree(prop->value);
114		kfree(prop);
115		prop = next;
116
117		if (!prop) {
118			prop = node->deadprops;
119			node->deadprops = NULL;
120		}
121	}
122	kfree(node->full_name);
123	kfree(node->data);
124	kfree(node);
125}
126
127/**
128 *	of_node_put - Decrement refcount of a node
129 *	@node:	Node to dec refcount, NULL is supported to
130 *		simplify writing of callers
131 *
132 */
133void of_node_put(struct device_node *node)
134{
135	if (node)
136		kref_put(&node->kref, of_node_release);
137}
138EXPORT_SYMBOL(of_node_put);
139#endif /* !CONFIG_SPARC */
140
141struct property *of_find_property(const struct device_node *np,
142				  const char *name,
143				  int *lenp)
144{
145	struct property *pp;
146
147	if (!np)
148		return NULL;
149
150	read_lock(&devtree_lock);
151	for (pp = np->properties; pp != 0; pp = pp->next) {
152		if (of_prop_cmp(pp->name, name) == 0) {
153			if (lenp != 0)
154				*lenp = pp->length;
155			break;
156		}
157	}
158	read_unlock(&devtree_lock);
159
160	return pp;
161}
162EXPORT_SYMBOL(of_find_property);
163
164/**
165 * of_find_all_nodes - Get next node in global list
166 * @prev:	Previous node or NULL to start iteration
167 *		of_node_put() will be called on it
168 *
169 * Returns a node pointer with refcount incremented, use
170 * of_node_put() on it when done.
171 */
172struct device_node *of_find_all_nodes(struct device_node *prev)
173{
174	struct device_node *np;
175
176	read_lock(&devtree_lock);
177	np = prev ? prev->allnext : allnodes;
178	for (; np != NULL; np = np->allnext)
179		if (of_node_get(np))
180			break;
181	of_node_put(prev);
182	read_unlock(&devtree_lock);
183	return np;
184}
185EXPORT_SYMBOL(of_find_all_nodes);
186
187/*
188 * Find a property with a given name for a given node
189 * and return the value.
190 */
191const void *of_get_property(const struct device_node *np, const char *name,
192			 int *lenp)
193{
194	struct property *pp = of_find_property(np, name, lenp);
195
196	return pp ? pp->value : NULL;
197}
198EXPORT_SYMBOL(of_get_property);
199
200/** Checks if the given "compat" string matches one of the strings in
201 * the device's "compatible" property
202 */
203int of_device_is_compatible(const struct device_node *device,
204		const char *compat)
205{
206	const char* cp;
207	int cplen, l;
208
209	cp = of_get_property(device, "compatible", &cplen);
210	if (cp == NULL)
211		return 0;
212	while (cplen > 0) {
213		if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
214			return 1;
215		l = strlen(cp) + 1;
216		cp += l;
217		cplen -= l;
218	}
219
220	return 0;
221}
222EXPORT_SYMBOL(of_device_is_compatible);
223
224/**
225 * of_machine_is_compatible - Test root of device tree for a given compatible value
226 * @compat: compatible string to look for in root node's compatible property.
227 *
228 * Returns true if the root node has the given value in its
229 * compatible property.
230 */
231int of_machine_is_compatible(const char *compat)
232{
233	struct device_node *root;
234	int rc = 0;
235
236	root = of_find_node_by_path("/");
237	if (root) {
238		rc = of_device_is_compatible(root, compat);
239		of_node_put(root);
240	}
241	return rc;
242}
243EXPORT_SYMBOL(of_machine_is_compatible);
244
245/**
246 *  of_device_is_available - check if a device is available for use
247 *
248 *  @device: Node to check for availability
249 *
250 *  Returns 1 if the status property is absent or set to "okay" or "ok",
251 *  0 otherwise
252 */
253int of_device_is_available(const struct device_node *device)
254{
255	const char *status;
256	int statlen;
257
258	status = of_get_property(device, "status", &statlen);
259	if (status == NULL)
260		return 1;
261
262	if (statlen > 0) {
263		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
264			return 1;
265	}
266
267	return 0;
268}
269EXPORT_SYMBOL(of_device_is_available);
270
271/**
272 *	of_get_parent - Get a node's parent if any
273 *	@node:	Node to get parent
274 *
275 *	Returns a node pointer with refcount incremented, use
276 *	of_node_put() on it when done.
277 */
278struct device_node *of_get_parent(const struct device_node *node)
279{
280	struct device_node *np;
281
282	if (!node)
283		return NULL;
284
285	read_lock(&devtree_lock);
286	np = of_node_get(node->parent);
287	read_unlock(&devtree_lock);
288	return np;
289}
290EXPORT_SYMBOL(of_get_parent);
291
292/**
293 *	of_get_next_parent - Iterate to a node's parent
294 *	@node:	Node to get parent of
295 *
296 * 	This is like of_get_parent() except that it drops the
297 * 	refcount on the passed node, making it suitable for iterating
298 * 	through a node's parents.
299 *
300 *	Returns a node pointer with refcount incremented, use
301 *	of_node_put() on it when done.
302 */
303struct device_node *of_get_next_parent(struct device_node *node)
304{
305	struct device_node *parent;
306
307	if (!node)
308		return NULL;
309
310	read_lock(&devtree_lock);
311	parent = of_node_get(node->parent);
312	of_node_put(node);
313	read_unlock(&devtree_lock);
314	return parent;
315}
316
317/**
318 *	of_get_next_child - Iterate a node childs
319 *	@node:	parent node
320 *	@prev:	previous child of the parent node, or NULL to get first
321 *
322 *	Returns a node pointer with refcount incremented, use
323 *	of_node_put() on it when done.
324 */
325struct device_node *of_get_next_child(const struct device_node *node,
326	struct device_node *prev)
327{
328	struct device_node *next;
329
330	read_lock(&devtree_lock);
331	next = prev ? prev->sibling : node->child;
332	for (; next; next = next->sibling)
333		if (of_node_get(next))
334			break;
335	of_node_put(prev);
336	read_unlock(&devtree_lock);
337	return next;
338}
339EXPORT_SYMBOL(of_get_next_child);
340
341/**
342 *	of_find_node_by_path - Find a node matching a full OF path
343 *	@path:	The full path to match
344 *
345 *	Returns a node pointer with refcount incremented, use
346 *	of_node_put() on it when done.
347 */
348struct device_node *of_find_node_by_path(const char *path)
349{
350	struct device_node *np = allnodes;
351
352	read_lock(&devtree_lock);
353	for (; np; np = np->allnext) {
354		if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
355		    && of_node_get(np))
356			break;
357	}
358	read_unlock(&devtree_lock);
359	return np;
360}
361EXPORT_SYMBOL(of_find_node_by_path);
362
363/**
364 *	of_find_node_by_name - Find a node by its "name" property
365 *	@from:	The node to start searching from or NULL, the node
366 *		you pass will not be searched, only the next one
367 *		will; typically, you pass what the previous call
368 *		returned. of_node_put() will be called on it
369 *	@name:	The name string to match against
370 *
371 *	Returns a node pointer with refcount incremented, use
372 *	of_node_put() on it when done.
373 */
374struct device_node *of_find_node_by_name(struct device_node *from,
375	const char *name)
376{
377	struct device_node *np;
378
379	read_lock(&devtree_lock);
380	np = from ? from->allnext : allnodes;
381	for (; np; np = np->allnext)
382		if (np->name && (of_node_cmp(np->name, name) == 0)
383		    && of_node_get(np))
384			break;
385	of_node_put(from);
386	read_unlock(&devtree_lock);
387	return np;
388}
389EXPORT_SYMBOL(of_find_node_by_name);
390
391/**
392 *	of_find_node_by_type - Find a node by its "device_type" property
393 *	@from:	The node to start searching from, or NULL to start searching
394 *		the entire device tree. The node you pass will not be
395 *		searched, only the next one will; typically, you pass
396 *		what the previous call returned. of_node_put() will be
397 *		called on from for you.
398 *	@type:	The type string to match against
399 *
400 *	Returns a node pointer with refcount incremented, use
401 *	of_node_put() on it when done.
402 */
403struct device_node *of_find_node_by_type(struct device_node *from,
404	const char *type)
405{
406	struct device_node *np;
407
408	read_lock(&devtree_lock);
409	np = from ? from->allnext : allnodes;
410	for (; np; np = np->allnext)
411		if (np->type && (of_node_cmp(np->type, type) == 0)
412		    && of_node_get(np))
413			break;
414	of_node_put(from);
415	read_unlock(&devtree_lock);
416	return np;
417}
418EXPORT_SYMBOL(of_find_node_by_type);
419
420/**
421 *	of_find_compatible_node - Find a node based on type and one of the
422 *                                tokens in its "compatible" property
423 *	@from:		The node to start searching from or NULL, the node
424 *			you pass will not be searched, only the next one
425 *			will; typically, you pass what the previous call
426 *			returned. of_node_put() will be called on it
427 *	@type:		The type string to match "device_type" or NULL to ignore
428 *	@compatible:	The string to match to one of the tokens in the device
429 *			"compatible" list.
430 *
431 *	Returns a node pointer with refcount incremented, use
432 *	of_node_put() on it when done.
433 */
434struct device_node *of_find_compatible_node(struct device_node *from,
435	const char *type, const char *compatible)
436{
437	struct device_node *np;
438
439	read_lock(&devtree_lock);
440	np = from ? from->allnext : allnodes;
441	for (; np; np = np->allnext) {
442		if (type
443		    && !(np->type && (of_node_cmp(np->type, type) == 0)))
444			continue;
445		if (of_device_is_compatible(np, compatible) && of_node_get(np))
446			break;
447	}
448	of_node_put(from);
449	read_unlock(&devtree_lock);
450	return np;
451}
452EXPORT_SYMBOL(of_find_compatible_node);
453
454/**
455 *	of_find_node_with_property - Find a node which has a property with
456 *                                   the given name.
457 *	@from:		The node to start searching from or NULL, the node
458 *			you pass will not be searched, only the next one
459 *			will; typically, you pass what the previous call
460 *			returned. of_node_put() will be called on it
461 *	@prop_name:	The name of the property to look for.
462 *
463 *	Returns a node pointer with refcount incremented, use
464 *	of_node_put() on it when done.
465 */
466struct device_node *of_find_node_with_property(struct device_node *from,
467	const char *prop_name)
468{
469	struct device_node *np;
470	struct property *pp;
471
472	read_lock(&devtree_lock);
473	np = from ? from->allnext : allnodes;
474	for (; np; np = np->allnext) {
475		for (pp = np->properties; pp != 0; pp = pp->next) {
476			if (of_prop_cmp(pp->name, prop_name) == 0) {
477				of_node_get(np);
478				goto out;
479			}
480		}
481	}
482out:
483	of_node_put(from);
484	read_unlock(&devtree_lock);
485	return np;
486}
487EXPORT_SYMBOL(of_find_node_with_property);
488
489/**
490 * of_match_node - Tell if an device_node has a matching of_match structure
491 *	@matches:	array of of device match structures to search in
492 *	@node:		the of device structure to match against
493 *
494 *	Low level utility function used by device matching.
495 */
496const struct of_device_id *of_match_node(const struct of_device_id *matches,
497					 const struct device_node *node)
498{
499	while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
500		int match = 1;
501		if (matches->name[0])
502			match &= node->name
503				&& !strcmp(matches->name, node->name);
504		if (matches->type[0])
505			match &= node->type
506				&& !strcmp(matches->type, node->type);
507		if (matches->compatible[0])
508			match &= of_device_is_compatible(node,
509						matches->compatible);
510		if (match)
511			return matches;
512		matches++;
513	}
514	return NULL;
515}
516EXPORT_SYMBOL(of_match_node);
517
518/**
519 *	of_find_matching_node - Find a node based on an of_device_id match
520 *				table.
521 *	@from:		The node to start searching from or NULL, the node
522 *			you pass will not be searched, only the next one
523 *			will; typically, you pass what the previous call
524 *			returned. of_node_put() will be called on it
525 *	@matches:	array of of device match structures to search in
526 *
527 *	Returns a node pointer with refcount incremented, use
528 *	of_node_put() on it when done.
529 */
530struct device_node *of_find_matching_node(struct device_node *from,
531					  const struct of_device_id *matches)
532{
533	struct device_node *np;
534
535	read_lock(&devtree_lock);
536	np = from ? from->allnext : allnodes;
537	for (; np; np = np->allnext) {
538		if (of_match_node(matches, np) && of_node_get(np))
539			break;
540	}
541	of_node_put(from);
542	read_unlock(&devtree_lock);
543	return np;
544}
545EXPORT_SYMBOL(of_find_matching_node);
546
547/**
548 * of_modalias_node - Lookup appropriate modalias for a device node
549 * @node:	pointer to a device tree node
550 * @modalias:	Pointer to buffer that modalias value will be copied into
551 * @len:	Length of modalias value
552 *
553 * Based on the value of the compatible property, this routine will attempt
554 * to choose an appropriate modalias value for a particular device tree node.
555 * It does this by stripping the manufacturer prefix (as delimited by a ',')
556 * from the first entry in the compatible list property.
557 *
558 * This routine returns 0 on success, <0 on failure.
559 */
560int of_modalias_node(struct device_node *node, char *modalias, int len)
561{
562	const char *compatible, *p;
563	int cplen;
564
565	compatible = of_get_property(node, "compatible", &cplen);
566	if (!compatible || strlen(compatible) > cplen)
567		return -ENODEV;
568	p = strchr(compatible, ',');
569	strlcpy(modalias, p ? p + 1 : compatible, len);
570	return 0;
571}
572EXPORT_SYMBOL_GPL(of_modalias_node);
573
574/**
575 * of_find_node_by_phandle - Find a node given a phandle
576 * @handle:	phandle of the node to find
577 *
578 * Returns a node pointer with refcount incremented, use
579 * of_node_put() on it when done.
580 */
581struct device_node *of_find_node_by_phandle(phandle handle)
582{
583	struct device_node *np;
584
585	read_lock(&devtree_lock);
586	for (np = allnodes; np; np = np->allnext)
587		if (np->phandle == handle)
588			break;
589	of_node_get(np);
590	read_unlock(&devtree_lock);
591	return np;
592}
593EXPORT_SYMBOL(of_find_node_by_phandle);
594
595/**
596 * of_parse_phandle - Resolve a phandle property to a device_node pointer
597 * @np: Pointer to device node holding phandle property
598 * @phandle_name: Name of property holding a phandle value
599 * @index: For properties holding a table of phandles, this is the index into
600 *         the table
601 *
602 * Returns the device_node pointer with refcount incremented.  Use
603 * of_node_put() on it when done.
604 */
605struct device_node *
606of_parse_phandle(struct device_node *np, const char *phandle_name, int index)
607{
608	const __be32 *phandle;
609	int size;
610
611	phandle = of_get_property(np, phandle_name, &size);
612	if ((!phandle) || (size < sizeof(*phandle) * (index + 1)))
613		return NULL;
614
615	return of_find_node_by_phandle(be32_to_cpup(phandle + index));
616}
617EXPORT_SYMBOL(of_parse_phandle);
618
619/**
620 * of_parse_phandles_with_args - Find a node pointed by phandle in a list
621 * @np:		pointer to a device tree node containing a list
622 * @list_name:	property name that contains a list
623 * @cells_name:	property name that specifies phandles' arguments count
624 * @index:	index of a phandle to parse out
625 * @out_node:	optional pointer to device_node struct pointer (will be filled)
626 * @out_args:	optional pointer to arguments pointer (will be filled)
627 *
628 * This function is useful to parse lists of phandles and their arguments.
629 * Returns 0 on success and fills out_node and out_args, on error returns
630 * appropriate errno value.
631 *
632 * Example:
633 *
634 * phandle1: node1 {
635 * 	#list-cells = <2>;
636 * }
637 *
638 * phandle2: node2 {
639 * 	#list-cells = <1>;
640 * }
641 *
642 * node3 {
643 * 	list = <&phandle1 1 2 &phandle2 3>;
644 * }
645 *
646 * To get a device_node of the `node2' node you may call this:
647 * of_parse_phandles_with_args(node3, "list", "#list-cells", 2, &node2, &args);
648 */
649int of_parse_phandles_with_args(struct device_node *np, const char *list_name,
650				const char *cells_name, int index,
651				struct device_node **out_node,
652				const void **out_args)
653{
654	int ret = -EINVAL;
655	const __be32 *list;
656	const __be32 *list_end;
657	int size;
658	int cur_index = 0;
659	struct device_node *node = NULL;
660	const void *args = NULL;
661
662	list = of_get_property(np, list_name, &size);
663	if (!list) {
664		ret = -ENOENT;
665		goto err0;
666	}
667	list_end = list + size / sizeof(*list);
668
669	while (list < list_end) {
670		const __be32 *cells;
671		phandle phandle;
672
673		phandle = be32_to_cpup(list++);
674		args = list;
675
676		/* one cell hole in the list = <>; */
677		if (!phandle)
678			goto next;
679
680		node = of_find_node_by_phandle(phandle);
681		if (!node) {
682			pr_debug("%s: could not find phandle\n",
683				 np->full_name);
684			goto err0;
685		}
686
687		cells = of_get_property(node, cells_name, &size);
688		if (!cells || size != sizeof(*cells)) {
689			pr_debug("%s: could not get %s for %s\n",
690				 np->full_name, cells_name, node->full_name);
691			goto err1;
692		}
693
694		list += be32_to_cpup(cells);
695		if (list > list_end) {
696			pr_debug("%s: insufficient arguments length\n",
697				 np->full_name);
698			goto err1;
699		}
700next:
701		if (cur_index == index)
702			break;
703
704		of_node_put(node);
705		node = NULL;
706		args = NULL;
707		cur_index++;
708	}
709
710	if (!node) {
711		/*
712		 * args w/o node indicates that the loop above has stopped at
713		 * the 'hole' cell. Report this differently.
714		 */
715		if (args)
716			ret = -EEXIST;
717		else
718			ret = -ENOENT;
719		goto err0;
720	}
721
722	if (out_node)
723		*out_node = node;
724	if (out_args)
725		*out_args = args;
726
727	return 0;
728err1:
729	of_node_put(node);
730err0:
731	pr_debug("%s failed with status %d\n", __func__, ret);
732	return ret;
733}
734EXPORT_SYMBOL(of_parse_phandles_with_args);
735
736/**
737 * prom_add_property - Add a property to a node
738 */
739int prom_add_property(struct device_node *np, struct property *prop)
740{
741	struct property **next;
742	unsigned long flags;
743
744	prop->next = NULL;
745	write_lock_irqsave(&devtree_lock, flags);
746	next = &np->properties;
747	while (*next) {
748		if (strcmp(prop->name, (*next)->name) == 0) {
749			/* duplicate ! don't insert it */
750			write_unlock_irqrestore(&devtree_lock, flags);
751			return -1;
752		}
753		next = &(*next)->next;
754	}
755	*next = prop;
756	write_unlock_irqrestore(&devtree_lock, flags);
757
758#ifdef CONFIG_PROC_DEVICETREE
759	/* try to add to proc as well if it was initialized */
760	if (np->pde)
761		proc_device_tree_add_prop(np->pde, prop);
762#endif /* CONFIG_PROC_DEVICETREE */
763
764	return 0;
765}
766
767/**
768 * prom_remove_property - Remove a property from a node.
769 *
770 * Note that we don't actually remove it, since we have given out
771 * who-knows-how-many pointers to the data using get-property.
772 * Instead we just move the property to the "dead properties"
773 * list, so it won't be found any more.
774 */
775int prom_remove_property(struct device_node *np, struct property *prop)
776{
777	struct property **next;
778	unsigned long flags;
779	int found = 0;
780
781	write_lock_irqsave(&devtree_lock, flags);
782	next = &np->properties;
783	while (*next) {
784		if (*next == prop) {
785			/* found the node */
786			*next = prop->next;
787			prop->next = np->deadprops;
788			np->deadprops = prop;
789			found = 1;
790			break;
791		}
792		next = &(*next)->next;
793	}
794	write_unlock_irqrestore(&devtree_lock, flags);
795
796	if (!found)
797		return -ENODEV;
798
799#ifdef CONFIG_PROC_DEVICETREE
800	/* try to remove the proc node as well */
801	if (np->pde)
802		proc_device_tree_remove_prop(np->pde, prop);
803#endif /* CONFIG_PROC_DEVICETREE */
804
805	return 0;
806}
807
808/*
809 * prom_update_property - Update a property in a node.
810 *
811 * Note that we don't actually remove it, since we have given out
812 * who-knows-how-many pointers to the data using get-property.
813 * Instead we just move the property to the "dead properties" list,
814 * and add the new property to the property list
815 */
816int prom_update_property(struct device_node *np,
817			 struct property *newprop,
818			 struct property *oldprop)
819{
820	struct property **next;
821	unsigned long flags;
822	int found = 0;
823
824	write_lock_irqsave(&devtree_lock, flags);
825	next = &np->properties;
826	while (*next) {
827		if (*next == oldprop) {
828			/* found the node */
829			newprop->next = oldprop->next;
830			*next = newprop;
831			oldprop->next = np->deadprops;
832			np->deadprops = oldprop;
833			found = 1;
834			break;
835		}
836		next = &(*next)->next;
837	}
838	write_unlock_irqrestore(&devtree_lock, flags);
839
840	if (!found)
841		return -ENODEV;
842
843#ifdef CONFIG_PROC_DEVICETREE
844	/* try to add to proc as well if it was initialized */
845	if (np->pde)
846		proc_device_tree_update_prop(np->pde, newprop, oldprop);
847#endif /* CONFIG_PROC_DEVICETREE */
848
849	return 0;
850}
851
852#if defined(CONFIG_OF_DYNAMIC)
853/*
854 * Support for dynamic device trees.
855 *
856 * On some platforms, the device tree can be manipulated at runtime.
857 * The routines in this section support adding, removing and changing
858 * device tree nodes.
859 */
860
861/**
862 * of_attach_node - Plug a device node into the tree and global list.
863 */
864void of_attach_node(struct device_node *np)
865{
866	unsigned long flags;
867
868	write_lock_irqsave(&devtree_lock, flags);
869	np->sibling = np->parent->child;
870	np->allnext = allnodes;
871	np->parent->child = np;
872	allnodes = np;
873	write_unlock_irqrestore(&devtree_lock, flags);
874}
875
876/**
877 * of_detach_node - "Unplug" a node from the device tree.
878 *
879 * The caller must hold a reference to the node.  The memory associated with
880 * the node is not freed until its refcount goes to zero.
881 */
882void of_detach_node(struct device_node *np)
883{
884	struct device_node *parent;
885	unsigned long flags;
886
887	write_lock_irqsave(&devtree_lock, flags);
888
889	parent = np->parent;
890	if (!parent)
891		goto out_unlock;
892
893	if (allnodes == np)
894		allnodes = np->allnext;
895	else {
896		struct device_node *prev;
897		for (prev = allnodes;
898		     prev->allnext != np;
899		     prev = prev->allnext)
900			;
901		prev->allnext = np->allnext;
902	}
903
904	if (parent->child == np)
905		parent->child = np->sibling;
906	else {
907		struct device_node *prevsib;
908		for (prevsib = np->parent->child;
909		     prevsib->sibling != np;
910		     prevsib = prevsib->sibling)
911			;
912		prevsib->sibling = np->sibling;
913	}
914
915	of_node_set_flag(np, OF_DETACHED);
916
917out_unlock:
918	write_unlock_irqrestore(&devtree_lock, flags);
919}
920#endif /* defined(CONFIG_OF_DYNAMIC) */
921