Root/drivers/of/base.c

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/ctype.h>
21#include <linux/module.h>
22#include <linux/of.h>
23#include <linux/spinlock.h>
24#include <linux/slab.h>
25#include <linux/proc_fs.h>
26
27/**
28 * struct alias_prop - Alias property in 'aliases' node
29 * @link: List node to link the structure in aliases_lookup list
30 * @alias: Alias property name
31 * @np: Pointer to device_node that the alias stands for
32 * @id: Index value from end of alias name
33 * @stem: Alias string without the index
34 *
35 * The structure represents one alias property of 'aliases' node as
36 * an entry in aliases_lookup list.
37 */
38struct alias_prop {
39    struct list_head link;
40    const char *alias;
41    struct device_node *np;
42    int id;
43    char stem[0];
44};
45
46static LIST_HEAD(aliases_lookup);
47
48struct device_node *allnodes;
49struct device_node *of_chosen;
50struct device_node *of_aliases;
51
52static DEFINE_MUTEX(of_aliases_mutex);
53
54/* use when traversing tree through the allnext, child, sibling,
55 * or parent members of struct device_node.
56 */
57DEFINE_RWLOCK(devtree_lock);
58
59int of_n_addr_cells(struct device_node *np)
60{
61    const __be32 *ip;
62
63    do {
64        if (np->parent)
65            np = np->parent;
66        ip = of_get_property(np, "#address-cells", NULL);
67        if (ip)
68            return be32_to_cpup(ip);
69    } while (np->parent);
70    /* No #address-cells property for the root node */
71    return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
72}
73EXPORT_SYMBOL(of_n_addr_cells);
74
75int of_n_size_cells(struct device_node *np)
76{
77    const __be32 *ip;
78
79    do {
80        if (np->parent)
81            np = np->parent;
82        ip = of_get_property(np, "#size-cells", NULL);
83        if (ip)
84            return be32_to_cpup(ip);
85    } while (np->parent);
86    /* No #size-cells property for the root node */
87    return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
88}
89EXPORT_SYMBOL(of_n_size_cells);
90
91#if defined(CONFIG_OF_DYNAMIC)
92/**
93 * of_node_get - Increment refcount of a node
94 * @node: Node to inc refcount, NULL is supported to
95 * simplify writing of callers
96 *
97 * Returns node.
98 */
99struct device_node *of_node_get(struct device_node *node)
100{
101    if (node)
102        kref_get(&node->kref);
103    return node;
104}
105EXPORT_SYMBOL(of_node_get);
106
107static inline struct device_node *kref_to_device_node(struct kref *kref)
108{
109    return container_of(kref, struct device_node, kref);
110}
111
112/**
113 * of_node_release - release a dynamically allocated node
114 * @kref: kref element of the node to be released
115 *
116 * In of_node_put() this function is passed to kref_put()
117 * as the destructor.
118 */
119static void of_node_release(struct kref *kref)
120{
121    struct device_node *node = kref_to_device_node(kref);
122    struct property *prop = node->properties;
123
124    /* We should never be releasing nodes that haven't been detached. */
125    if (!of_node_check_flag(node, OF_DETACHED)) {
126        pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
127        dump_stack();
128        kref_init(&node->kref);
129        return;
130    }
131
132    if (!of_node_check_flag(node, OF_DYNAMIC))
133        return;
134
135    while (prop) {
136        struct property *next = prop->next;
137        kfree(prop->name);
138        kfree(prop->value);
139        kfree(prop);
140        prop = next;
141
142        if (!prop) {
143            prop = node->deadprops;
144            node->deadprops = NULL;
145        }
146    }
147    kfree(node->full_name);
148    kfree(node->data);
149    kfree(node);
150}
151
152/**
153 * of_node_put - Decrement refcount of a node
154 * @node: Node to dec refcount, NULL is supported to
155 * simplify writing of callers
156 *
157 */
158void of_node_put(struct device_node *node)
159{
160    if (node)
161        kref_put(&node->kref, of_node_release);
162}
163EXPORT_SYMBOL(of_node_put);
164#endif /* CONFIG_OF_DYNAMIC */
165
166struct property *of_find_property(const struct device_node *np,
167                  const char *name,
168                  int *lenp)
169{
170    struct property *pp;
171
172    if (!np)
173        return NULL;
174
175    read_lock(&devtree_lock);
176    for (pp = np->properties; pp; pp = pp->next) {
177        if (of_prop_cmp(pp->name, name) == 0) {
178            if (lenp)
179                *lenp = pp->length;
180            break;
181        }
182    }
183    read_unlock(&devtree_lock);
184
185    return pp;
186}
187EXPORT_SYMBOL(of_find_property);
188
189/**
190 * of_find_all_nodes - Get next node in global list
191 * @prev: Previous node or NULL to start iteration
192 * of_node_put() will be called on it
193 *
194 * Returns a node pointer with refcount incremented, use
195 * of_node_put() on it when done.
196 */
197struct device_node *of_find_all_nodes(struct device_node *prev)
198{
199    struct device_node *np;
200
201    read_lock(&devtree_lock);
202    np = prev ? prev->allnext : allnodes;
203    for (; np != NULL; np = np->allnext)
204        if (of_node_get(np))
205            break;
206    of_node_put(prev);
207    read_unlock(&devtree_lock);
208    return np;
209}
210EXPORT_SYMBOL(of_find_all_nodes);
211
212/*
213 * Find a property with a given name for a given node
214 * and return the value.
215 */
216const void *of_get_property(const struct device_node *np, const char *name,
217             int *lenp)
218{
219    struct property *pp = of_find_property(np, name, lenp);
220
221    return pp ? pp->value : NULL;
222}
223EXPORT_SYMBOL(of_get_property);
224
225/** Checks if the given "compat" string matches one of the strings in
226 * the device's "compatible" property
227 */
228int of_device_is_compatible(const struct device_node *device,
229        const char *compat)
230{
231    const char* cp;
232    int cplen, l;
233
234    cp = of_get_property(device, "compatible", &cplen);
235    if (cp == NULL)
236        return 0;
237    while (cplen > 0) {
238        if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
239            return 1;
240        l = strlen(cp) + 1;
241        cp += l;
242        cplen -= l;
243    }
244
245    return 0;
246}
247EXPORT_SYMBOL(of_device_is_compatible);
248
249/**
250 * of_machine_is_compatible - Test root of device tree for a given compatible value
251 * @compat: compatible string to look for in root node's compatible property.
252 *
253 * Returns true if the root node has the given value in its
254 * compatible property.
255 */
256int of_machine_is_compatible(const char *compat)
257{
258    struct device_node *root;
259    int rc = 0;
260
261    root = of_find_node_by_path("/");
262    if (root) {
263        rc = of_device_is_compatible(root, compat);
264        of_node_put(root);
265    }
266    return rc;
267}
268EXPORT_SYMBOL(of_machine_is_compatible);
269
270/**
271 * of_device_is_available - check if a device is available for use
272 *
273 * @device: Node to check for availability
274 *
275 * Returns 1 if the status property is absent or set to "okay" or "ok",
276 * 0 otherwise
277 */
278int of_device_is_available(const struct device_node *device)
279{
280    const char *status;
281    int statlen;
282
283    status = of_get_property(device, "status", &statlen);
284    if (status == NULL)
285        return 1;
286
287    if (statlen > 0) {
288        if (!strcmp(status, "okay") || !strcmp(status, "ok"))
289            return 1;
290    }
291
292    return 0;
293}
294EXPORT_SYMBOL(of_device_is_available);
295
296/**
297 * of_get_parent - Get a node's parent if any
298 * @node: Node to get parent
299 *
300 * Returns a node pointer with refcount incremented, use
301 * of_node_put() on it when done.
302 */
303struct device_node *of_get_parent(const struct device_node *node)
304{
305    struct device_node *np;
306
307    if (!node)
308        return NULL;
309
310    read_lock(&devtree_lock);
311    np = of_node_get(node->parent);
312    read_unlock(&devtree_lock);
313    return np;
314}
315EXPORT_SYMBOL(of_get_parent);
316
317/**
318 * of_get_next_parent - Iterate to a node's parent
319 * @node: Node to get parent of
320 *
321 * This is like of_get_parent() except that it drops the
322 * refcount on the passed node, making it suitable for iterating
323 * through a node's parents.
324 *
325 * Returns a node pointer with refcount incremented, use
326 * of_node_put() on it when done.
327 */
328struct device_node *of_get_next_parent(struct device_node *node)
329{
330    struct device_node *parent;
331
332    if (!node)
333        return NULL;
334
335    read_lock(&devtree_lock);
336    parent = of_node_get(node->parent);
337    of_node_put(node);
338    read_unlock(&devtree_lock);
339    return parent;
340}
341
342/**
343 * of_get_next_child - Iterate a node childs
344 * @node: parent node
345 * @prev: previous child of the parent node, or NULL to get first
346 *
347 * Returns a node pointer with refcount incremented, use
348 * of_node_put() on it when done.
349 */
350struct device_node *of_get_next_child(const struct device_node *node,
351    struct device_node *prev)
352{
353    struct device_node *next;
354
355    read_lock(&devtree_lock);
356    next = prev ? prev->sibling : node->child;
357    for (; next; next = next->sibling)
358        if (of_node_get(next))
359            break;
360    of_node_put(prev);
361    read_unlock(&devtree_lock);
362    return next;
363}
364EXPORT_SYMBOL(of_get_next_child);
365
366/**
367 * of_get_next_available_child - Find the next available child node
368 * @node: parent node
369 * @prev: previous child of the parent node, or NULL to get first
370 *
371 * This function is like of_get_next_child(), except that it
372 * automatically skips any disabled nodes (i.e. status = "disabled").
373 */
374struct device_node *of_get_next_available_child(const struct device_node *node,
375    struct device_node *prev)
376{
377    struct device_node *next;
378
379    read_lock(&devtree_lock);
380    next = prev ? prev->sibling : node->child;
381    for (; next; next = next->sibling) {
382        if (!of_device_is_available(next))
383            continue;
384        if (of_node_get(next))
385            break;
386    }
387    of_node_put(prev);
388    read_unlock(&devtree_lock);
389    return next;
390}
391EXPORT_SYMBOL(of_get_next_available_child);
392
393/**
394 * of_find_node_by_path - Find a node matching a full OF path
395 * @path: The full path to match
396 *
397 * Returns a node pointer with refcount incremented, use
398 * of_node_put() on it when done.
399 */
400struct device_node *of_find_node_by_path(const char *path)
401{
402    struct device_node *np = allnodes;
403
404    read_lock(&devtree_lock);
405    for (; np; np = np->allnext) {
406        if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
407            && of_node_get(np))
408            break;
409    }
410    read_unlock(&devtree_lock);
411    return np;
412}
413EXPORT_SYMBOL(of_find_node_by_path);
414
415/**
416 * of_find_node_by_name - Find a node by its "name" property
417 * @from: The node to start searching from or NULL, the node
418 * you pass will not be searched, only the next one
419 * will; typically, you pass what the previous call
420 * returned. of_node_put() will be called on it
421 * @name: The name string to match against
422 *
423 * Returns a node pointer with refcount incremented, use
424 * of_node_put() on it when done.
425 */
426struct device_node *of_find_node_by_name(struct device_node *from,
427    const char *name)
428{
429    struct device_node *np;
430
431    read_lock(&devtree_lock);
432    np = from ? from->allnext : allnodes;
433    for (; np; np = np->allnext)
434        if (np->name && (of_node_cmp(np->name, name) == 0)
435            && of_node_get(np))
436            break;
437    of_node_put(from);
438    read_unlock(&devtree_lock);
439    return np;
440}
441EXPORT_SYMBOL(of_find_node_by_name);
442
443/**
444 * of_find_node_by_type - Find a node by its "device_type" property
445 * @from: The node to start searching from, or NULL to start searching
446 * the entire device tree. The node you pass will not be
447 * searched, only the next one will; typically, you pass
448 * what the previous call returned. of_node_put() will be
449 * called on from for you.
450 * @type: The type string to match against
451 *
452 * Returns a node pointer with refcount incremented, use
453 * of_node_put() on it when done.
454 */
455struct device_node *of_find_node_by_type(struct device_node *from,
456    const char *type)
457{
458    struct device_node *np;
459
460    read_lock(&devtree_lock);
461    np = from ? from->allnext : allnodes;
462    for (; np; np = np->allnext)
463        if (np->type && (of_node_cmp(np->type, type) == 0)
464            && of_node_get(np))
465            break;
466    of_node_put(from);
467    read_unlock(&devtree_lock);
468    return np;
469}
470EXPORT_SYMBOL(of_find_node_by_type);
471
472/**
473 * of_find_compatible_node - Find a node based on type and one of the
474 * tokens in its "compatible" property
475 * @from: The node to start searching from or NULL, the node
476 * you pass will not be searched, only the next one
477 * will; typically, you pass what the previous call
478 * returned. of_node_put() will be called on it
479 * @type: The type string to match "device_type" or NULL to ignore
480 * @compatible: The string to match to one of the tokens in the device
481 * "compatible" list.
482 *
483 * Returns a node pointer with refcount incremented, use
484 * of_node_put() on it when done.
485 */
486struct device_node *of_find_compatible_node(struct device_node *from,
487    const char *type, const char *compatible)
488{
489    struct device_node *np;
490
491    read_lock(&devtree_lock);
492    np = from ? from->allnext : allnodes;
493    for (; np; np = np->allnext) {
494        if (type
495            && !(np->type && (of_node_cmp(np->type, type) == 0)))
496            continue;
497        if (of_device_is_compatible(np, compatible) && of_node_get(np))
498            break;
499    }
500    of_node_put(from);
501    read_unlock(&devtree_lock);
502    return np;
503}
504EXPORT_SYMBOL(of_find_compatible_node);
505
506/**
507 * of_find_node_with_property - Find a node which has a property with
508 * the given name.
509 * @from: The node to start searching from or NULL, the node
510 * you pass will not be searched, only the next one
511 * will; typically, you pass what the previous call
512 * returned. of_node_put() will be called on it
513 * @prop_name: The name of the property to look for.
514 *
515 * Returns a node pointer with refcount incremented, use
516 * of_node_put() on it when done.
517 */
518struct device_node *of_find_node_with_property(struct device_node *from,
519    const char *prop_name)
520{
521    struct device_node *np;
522    struct property *pp;
523
524    read_lock(&devtree_lock);
525    np = from ? from->allnext : allnodes;
526    for (; np; np = np->allnext) {
527        for (pp = np->properties; pp; pp = pp->next) {
528            if (of_prop_cmp(pp->name, prop_name) == 0) {
529                of_node_get(np);
530                goto out;
531            }
532        }
533    }
534out:
535    of_node_put(from);
536    read_unlock(&devtree_lock);
537    return np;
538}
539EXPORT_SYMBOL(of_find_node_with_property);
540
541/**
542 * of_match_node - Tell if an device_node has a matching of_match structure
543 * @matches: array of of device match structures to search in
544 * @node: the of device structure to match against
545 *
546 * Low level utility function used by device matching.
547 */
548const struct of_device_id *of_match_node(const struct of_device_id *matches,
549                     const struct device_node *node)
550{
551    if (!matches)
552        return NULL;
553
554    while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
555        int match = 1;
556        if (matches->name[0])
557            match &= node->name
558                && !strcmp(matches->name, node->name);
559        if (matches->type[0])
560            match &= node->type
561                && !strcmp(matches->type, node->type);
562        if (matches->compatible[0])
563            match &= of_device_is_compatible(node,
564                        matches->compatible);
565        if (match)
566            return matches;
567        matches++;
568    }
569    return NULL;
570}
571EXPORT_SYMBOL(of_match_node);
572
573/**
574 * of_find_matching_node - Find a node based on an of_device_id match
575 * table.
576 * @from: The node to start searching from or NULL, the node
577 * you pass will not be searched, only the next one
578 * will; typically, you pass what the previous call
579 * returned. of_node_put() will be called on it
580 * @matches: array of of device match structures to search in
581 *
582 * Returns a node pointer with refcount incremented, use
583 * of_node_put() on it when done.
584 */
585struct device_node *of_find_matching_node(struct device_node *from,
586                      const struct of_device_id *matches)
587{
588    struct device_node *np;
589
590    read_lock(&devtree_lock);
591    np = from ? from->allnext : allnodes;
592    for (; np; np = np->allnext) {
593        if (of_match_node(matches, np) && of_node_get(np))
594            break;
595    }
596    of_node_put(from);
597    read_unlock(&devtree_lock);
598    return np;
599}
600EXPORT_SYMBOL(of_find_matching_node);
601
602/**
603 * of_modalias_node - Lookup appropriate modalias for a device node
604 * @node: pointer to a device tree node
605 * @modalias: Pointer to buffer that modalias value will be copied into
606 * @len: Length of modalias value
607 *
608 * Based on the value of the compatible property, this routine will attempt
609 * to choose an appropriate modalias value for a particular device tree node.
610 * It does this by stripping the manufacturer prefix (as delimited by a ',')
611 * from the first entry in the compatible list property.
612 *
613 * This routine returns 0 on success, <0 on failure.
614 */
615int of_modalias_node(struct device_node *node, char *modalias, int len)
616{
617    const char *compatible, *p;
618    int cplen;
619
620    compatible = of_get_property(node, "compatible", &cplen);
621    if (!compatible || strlen(compatible) > cplen)
622        return -ENODEV;
623    p = strchr(compatible, ',');
624    strlcpy(modalias, p ? p + 1 : compatible, len);
625    return 0;
626}
627EXPORT_SYMBOL_GPL(of_modalias_node);
628
629/**
630 * of_find_node_by_phandle - Find a node given a phandle
631 * @handle: phandle of the node to find
632 *
633 * Returns a node pointer with refcount incremented, use
634 * of_node_put() on it when done.
635 */
636struct device_node *of_find_node_by_phandle(phandle handle)
637{
638    struct device_node *np;
639
640    read_lock(&devtree_lock);
641    for (np = allnodes; np; np = np->allnext)
642        if (np->phandle == handle)
643            break;
644    of_node_get(np);
645    read_unlock(&devtree_lock);
646    return np;
647}
648EXPORT_SYMBOL(of_find_node_by_phandle);
649
650/**
651 * of_property_read_u32_array - Find and read an array of 32 bit integers
652 * from a property.
653 *
654 * @np: device node from which the property value is to be read.
655 * @propname: name of the property to be searched.
656 * @out_value: pointer to return value, modified only if return value is 0.
657 *
658 * Search for a property in a device node and read 32-bit value(s) from
659 * it. Returns 0 on success, -EINVAL if the property does not exist,
660 * -ENODATA if property does not have a value, and -EOVERFLOW if the
661 * property data isn't large enough.
662 *
663 * The out_value is modified only if a valid u32 value can be decoded.
664 */
665int of_property_read_u32_array(const struct device_node *np,
666                   const char *propname, u32 *out_values,
667                   size_t sz)
668{
669    struct property *prop = of_find_property(np, propname, NULL);
670    const __be32 *val;
671
672    if (!prop)
673        return -EINVAL;
674    if (!prop->value)
675        return -ENODATA;
676    if ((sz * sizeof(*out_values)) > prop->length)
677        return -EOVERFLOW;
678
679    val = prop->value;
680    while (sz--)
681        *out_values++ = be32_to_cpup(val++);
682    return 0;
683}
684EXPORT_SYMBOL_GPL(of_property_read_u32_array);
685
686/**
687 * of_property_read_u64 - Find and read a 64 bit integer from a property
688 * @np: device node from which the property value is to be read.
689 * @propname: name of the property to be searched.
690 * @out_value: pointer to return value, modified only if return value is 0.
691 *
692 * Search for a property in a device node and read a 64-bit value from
693 * it. Returns 0 on success, -EINVAL if the property does not exist,
694 * -ENODATA if property does not have a value, and -EOVERFLOW if the
695 * property data isn't large enough.
696 *
697 * The out_value is modified only if a valid u64 value can be decoded.
698 */
699int of_property_read_u64(const struct device_node *np, const char *propname,
700             u64 *out_value)
701{
702    struct property *prop = of_find_property(np, propname, NULL);
703
704    if (!prop)
705        return -EINVAL;
706    if (!prop->value)
707        return -ENODATA;
708    if (sizeof(*out_value) > prop->length)
709        return -EOVERFLOW;
710    *out_value = of_read_number(prop->value, 2);
711    return 0;
712}
713EXPORT_SYMBOL_GPL(of_property_read_u64);
714
715/**
716 * of_property_read_string - Find and read a string from a property
717 * @np: device node from which the property value is to be read.
718 * @propname: name of the property to be searched.
719 * @out_string: pointer to null terminated return string, modified only if
720 * return value is 0.
721 *
722 * Search for a property in a device tree node and retrieve a null
723 * terminated string value (pointer to data, not a copy). Returns 0 on
724 * success, -EINVAL if the property does not exist, -ENODATA if property
725 * does not have a value, and -EILSEQ if the string is not null-terminated
726 * within the length of the property data.
727 *
728 * The out_string pointer is modified only if a valid string can be decoded.
729 */
730int of_property_read_string(struct device_node *np, const char *propname,
731                const char **out_string)
732{
733    struct property *prop = of_find_property(np, propname, NULL);
734    if (!prop)
735        return -EINVAL;
736    if (!prop->value)
737        return -ENODATA;
738    if (strnlen(prop->value, prop->length) >= prop->length)
739        return -EILSEQ;
740    *out_string = prop->value;
741    return 0;
742}
743EXPORT_SYMBOL_GPL(of_property_read_string);
744
745/**
746 * of_property_read_string_index - Find and read a string from a multiple
747 * strings property.
748 * @np: device node from which the property value is to be read.
749 * @propname: name of the property to be searched.
750 * @index: index of the string in the list of strings
751 * @out_string: pointer to null terminated return string, modified only if
752 * return value is 0.
753 *
754 * Search for a property in a device tree node and retrieve a null
755 * terminated string value (pointer to data, not a copy) in the list of strings
756 * contained in that property.
757 * Returns 0 on success, -EINVAL if the property does not exist, -ENODATA if
758 * property does not have a value, and -EILSEQ if the string is not
759 * null-terminated within the length of the property data.
760 *
761 * The out_string pointer is modified only if a valid string can be decoded.
762 */
763int of_property_read_string_index(struct device_node *np, const char *propname,
764                  int index, const char **output)
765{
766    struct property *prop = of_find_property(np, propname, NULL);
767    int i = 0;
768    size_t l = 0, total = 0;
769    const char *p;
770
771    if (!prop)
772        return -EINVAL;
773    if (!prop->value)
774        return -ENODATA;
775    if (strnlen(prop->value, prop->length) >= prop->length)
776        return -EILSEQ;
777
778    p = prop->value;
779
780    for (i = 0; total < prop->length; total += l, p += l) {
781        l = strlen(p) + 1;
782        if (i++ == index) {
783            *output = p;
784            return 0;
785        }
786    }
787    return -ENODATA;
788}
789EXPORT_SYMBOL_GPL(of_property_read_string_index);
790
791/**
792 * of_property_match_string() - Find string in a list and return index
793 * @np: pointer to node containing string list property
794 * @propname: string list property name
795 * @string: pointer to string to search for in string list
796 *
797 * This function searches a string list property and returns the index
798 * of a specific string value.
799 */
800int of_property_match_string(struct device_node *np, const char *propname,
801                 const char *string)
802{
803    struct property *prop = of_find_property(np, propname, NULL);
804    size_t l;
805    int i;
806    const char *p, *end;
807
808    if (!prop)
809        return -EINVAL;
810    if (!prop->value)
811        return -ENODATA;
812
813    p = prop->value;
814    end = p + prop->length;
815
816    for (i = 0; p < end; i++, p += l) {
817        l = strlen(p) + 1;
818        if (p + l > end)
819            return -EILSEQ;
820        pr_debug("comparing %s with %s\n", string, p);
821        if (strcmp(string, p) == 0)
822            return i; /* Found it; return index */
823    }
824    return -ENODATA;
825}
826EXPORT_SYMBOL_GPL(of_property_match_string);
827
828/**
829 * of_property_count_strings - Find and return the number of strings from a
830 * multiple strings property.
831 * @np: device node from which the property value is to be read.
832 * @propname: name of the property to be searched.
833 *
834 * Search for a property in a device tree node and retrieve the number of null
835 * terminated string contain in it. Returns the number of strings on
836 * success, -EINVAL if the property does not exist, -ENODATA if property
837 * does not have a value, and -EILSEQ if the string is not null-terminated
838 * within the length of the property data.
839 */
840int of_property_count_strings(struct device_node *np, const char *propname)
841{
842    struct property *prop = of_find_property(np, propname, NULL);
843    int i = 0;
844    size_t l = 0, total = 0;
845    const char *p;
846
847    if (!prop)
848        return -EINVAL;
849    if (!prop->value)
850        return -ENODATA;
851    if (strnlen(prop->value, prop->length) >= prop->length)
852        return -EILSEQ;
853
854    p = prop->value;
855
856    for (i = 0; total < prop->length; total += l, p += l, i++)
857        l = strlen(p) + 1;
858
859    return i;
860}
861EXPORT_SYMBOL_GPL(of_property_count_strings);
862
863/**
864 * of_parse_phandle - Resolve a phandle property to a device_node pointer
865 * @np: Pointer to device node holding phandle property
866 * @phandle_name: Name of property holding a phandle value
867 * @index: For properties holding a table of phandles, this is the index into
868 * the table
869 *
870 * Returns the device_node pointer with refcount incremented. Use
871 * of_node_put() on it when done.
872 */
873struct device_node *
874of_parse_phandle(struct device_node *np, const char *phandle_name, int index)
875{
876    const __be32 *phandle;
877    int size;
878
879    phandle = of_get_property(np, phandle_name, &size);
880    if ((!phandle) || (size < sizeof(*phandle) * (index + 1)))
881        return NULL;
882
883    return of_find_node_by_phandle(be32_to_cpup(phandle + index));
884}
885EXPORT_SYMBOL(of_parse_phandle);
886
887/**
888 * of_parse_phandle_with_args() - Find a node pointed by phandle in a list
889 * @np: pointer to a device tree node containing a list
890 * @list_name: property name that contains a list
891 * @cells_name: property name that specifies phandles' arguments count
892 * @index: index of a phandle to parse out
893 * @out_args: optional pointer to output arguments structure (will be filled)
894 *
895 * This function is useful to parse lists of phandles and their arguments.
896 * Returns 0 on success and fills out_args, on error returns appropriate
897 * errno value.
898 *
899 * Caller is responsible to call of_node_put() on the returned out_args->node
900 * pointer.
901 *
902 * Example:
903 *
904 * phandle1: node1 {
905 * #list-cells = <2>;
906 * }
907 *
908 * phandle2: node2 {
909 * #list-cells = <1>;
910 * }
911 *
912 * node3 {
913 * list = <&phandle1 1 2 &phandle2 3>;
914 * }
915 *
916 * To get a device_node of the `node2' node you may call this:
917 * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args);
918 */
919int of_parse_phandle_with_args(struct device_node *np, const char *list_name,
920                const char *cells_name, int index,
921                struct of_phandle_args *out_args)
922{
923    const __be32 *list, *list_end;
924    int size, cur_index = 0;
925    uint32_t count = 0;
926    struct device_node *node = NULL;
927    phandle phandle;
928
929    /* Retrieve the phandle list property */
930    list = of_get_property(np, list_name, &size);
931    if (!list)
932        return -ENOENT;
933    list_end = list + size / sizeof(*list);
934
935    /* Loop over the phandles until all the requested entry is found */
936    while (list < list_end) {
937        count = 0;
938
939        /*
940         * If phandle is 0, then it is an empty entry with no
941         * arguments. Skip forward to the next entry.
942         */
943        phandle = be32_to_cpup(list++);
944        if (phandle) {
945            /*
946             * Find the provider node and parse the #*-cells
947             * property to determine the argument length
948             */
949            node = of_find_node_by_phandle(phandle);
950            if (!node) {
951                pr_err("%s: could not find phandle\n",
952                     np->full_name);
953                break;
954            }
955            if (of_property_read_u32(node, cells_name, &count)) {
956                pr_err("%s: could not get %s for %s\n",
957                     np->full_name, cells_name,
958                     node->full_name);
959                break;
960            }
961
962            /*
963             * Make sure that the arguments actually fit in the
964             * remaining property data length
965             */
966            if (list + count > list_end) {
967                pr_err("%s: arguments longer than property\n",
968                     np->full_name);
969                break;
970            }
971        }
972
973        /*
974         * All of the error cases above bail out of the loop, so at
975         * this point, the parsing is successful. If the requested
976         * index matches, then fill the out_args structure and return,
977         * or return -ENOENT for an empty entry.
978         */
979        if (cur_index == index) {
980            if (!phandle)
981                return -ENOENT;
982
983            if (out_args) {
984                int i;
985                if (WARN_ON(count > MAX_PHANDLE_ARGS))
986                    count = MAX_PHANDLE_ARGS;
987                out_args->np = node;
988                out_args->args_count = count;
989                for (i = 0; i < count; i++)
990                    out_args->args[i] = be32_to_cpup(list++);
991            }
992            return 0;
993        }
994
995        of_node_put(node);
996        node = NULL;
997        list += count;
998        cur_index++;
999    }
1000
1001    /* Loop exited without finding a valid entry; return an error */
1002    if (node)
1003        of_node_put(node);
1004    return -EINVAL;
1005}
1006EXPORT_SYMBOL(of_parse_phandle_with_args);
1007
1008/**
1009 * prom_add_property - Add a property to a node
1010 */
1011int prom_add_property(struct device_node *np, struct property *prop)
1012{
1013    struct property **next;
1014    unsigned long flags;
1015
1016    prop->next = NULL;
1017    write_lock_irqsave(&devtree_lock, flags);
1018    next = &np->properties;
1019    while (*next) {
1020        if (strcmp(prop->name, (*next)->name) == 0) {
1021            /* duplicate ! don't insert it */
1022            write_unlock_irqrestore(&devtree_lock, flags);
1023            return -1;
1024        }
1025        next = &(*next)->next;
1026    }
1027    *next = prop;
1028    write_unlock_irqrestore(&devtree_lock, flags);
1029
1030#ifdef CONFIG_PROC_DEVICETREE
1031    /* try to add to proc as well if it was initialized */
1032    if (np->pde)
1033        proc_device_tree_add_prop(np->pde, prop);
1034#endif /* CONFIG_PROC_DEVICETREE */
1035
1036    return 0;
1037}
1038
1039/**
1040 * prom_remove_property - Remove a property from a node.
1041 *
1042 * Note that we don't actually remove it, since we have given out
1043 * who-knows-how-many pointers to the data using get-property.
1044 * Instead we just move the property to the "dead properties"
1045 * list, so it won't be found any more.
1046 */
1047int prom_remove_property(struct device_node *np, struct property *prop)
1048{
1049    struct property **next;
1050    unsigned long flags;
1051    int found = 0;
1052
1053    write_lock_irqsave(&devtree_lock, flags);
1054    next = &np->properties;
1055    while (*next) {
1056        if (*next == prop) {
1057            /* found the node */
1058            *next = prop->next;
1059            prop->next = np->deadprops;
1060            np->deadprops = prop;
1061            found = 1;
1062            break;
1063        }
1064        next = &(*next)->next;
1065    }
1066    write_unlock_irqrestore(&devtree_lock, flags);
1067
1068    if (!found)
1069        return -ENODEV;
1070
1071#ifdef CONFIG_PROC_DEVICETREE
1072    /* try to remove the proc node as well */
1073    if (np->pde)
1074        proc_device_tree_remove_prop(np->pde, prop);
1075#endif /* CONFIG_PROC_DEVICETREE */
1076
1077    return 0;
1078}
1079
1080/*
1081 * prom_update_property - Update a property in a node, if the property does
1082 * not exist, add it.
1083 *
1084 * Note that we don't actually remove it, since we have given out
1085 * who-knows-how-many pointers to the data using get-property.
1086 * Instead we just move the property to the "dead properties" list,
1087 * and add the new property to the property list
1088 */
1089int prom_update_property(struct device_node *np,
1090             struct property *newprop)
1091{
1092    struct property **next, *oldprop;
1093    unsigned long flags;
1094    int found = 0;
1095
1096    if (!newprop->name)
1097        return -EINVAL;
1098
1099    oldprop = of_find_property(np, newprop->name, NULL);
1100    if (!oldprop)
1101        return prom_add_property(np, newprop);
1102
1103    write_lock_irqsave(&devtree_lock, flags);
1104    next = &np->properties;
1105    while (*next) {
1106        if (*next == oldprop) {
1107            /* found the node */
1108            newprop->next = oldprop->next;
1109            *next = newprop;
1110            oldprop->next = np->deadprops;
1111            np->deadprops = oldprop;
1112            found = 1;
1113            break;
1114        }
1115        next = &(*next)->next;
1116    }
1117    write_unlock_irqrestore(&devtree_lock, flags);
1118
1119    if (!found)
1120        return -ENODEV;
1121
1122#ifdef CONFIG_PROC_DEVICETREE
1123    /* try to add to proc as well if it was initialized */
1124    if (np->pde)
1125        proc_device_tree_update_prop(np->pde, newprop, oldprop);
1126#endif /* CONFIG_PROC_DEVICETREE */
1127
1128    return 0;
1129}
1130
1131#if defined(CONFIG_OF_DYNAMIC)
1132/*
1133 * Support for dynamic device trees.
1134 *
1135 * On some platforms, the device tree can be manipulated at runtime.
1136 * The routines in this section support adding, removing and changing
1137 * device tree nodes.
1138 */
1139
1140/**
1141 * of_attach_node - Plug a device node into the tree and global list.
1142 */
1143void of_attach_node(struct device_node *np)
1144{
1145    unsigned long flags;
1146
1147    write_lock_irqsave(&devtree_lock, flags);
1148    np->sibling = np->parent->child;
1149    np->allnext = allnodes;
1150    np->parent->child = np;
1151    allnodes = np;
1152    write_unlock_irqrestore(&devtree_lock, flags);
1153}
1154
1155/**
1156 * of_detach_node - "Unplug" a node from the device tree.
1157 *
1158 * The caller must hold a reference to the node. The memory associated with
1159 * the node is not freed until its refcount goes to zero.
1160 */
1161void of_detach_node(struct device_node *np)
1162{
1163    struct device_node *parent;
1164    unsigned long flags;
1165
1166    write_lock_irqsave(&devtree_lock, flags);
1167
1168    parent = np->parent;
1169    if (!parent)
1170        goto out_unlock;
1171
1172    if (allnodes == np)
1173        allnodes = np->allnext;
1174    else {
1175        struct device_node *prev;
1176        for (prev = allnodes;
1177             prev->allnext != np;
1178             prev = prev->allnext)
1179            ;
1180        prev->allnext = np->allnext;
1181    }
1182
1183    if (parent->child == np)
1184        parent->child = np->sibling;
1185    else {
1186        struct device_node *prevsib;
1187        for (prevsib = np->parent->child;
1188             prevsib->sibling != np;
1189             prevsib = prevsib->sibling)
1190            ;
1191        prevsib->sibling = np->sibling;
1192    }
1193
1194    of_node_set_flag(np, OF_DETACHED);
1195
1196out_unlock:
1197    write_unlock_irqrestore(&devtree_lock, flags);
1198}
1199#endif /* defined(CONFIG_OF_DYNAMIC) */
1200
1201static void of_alias_add(struct alias_prop *ap, struct device_node *np,
1202             int id, const char *stem, int stem_len)
1203{
1204    ap->np = np;
1205    ap->id = id;
1206    strncpy(ap->stem, stem, stem_len);
1207    ap->stem[stem_len] = 0;
1208    list_add_tail(&ap->link, &aliases_lookup);
1209    pr_debug("adding DT alias:%s: stem=%s id=%i node=%s\n",
1210         ap->alias, ap->stem, ap->id, of_node_full_name(np));
1211}
1212
1213/**
1214 * of_alias_scan - Scan all properties of 'aliases' node
1215 *
1216 * The function scans all the properties of 'aliases' node and populate
1217 * the the global lookup table with the properties. It returns the
1218 * number of alias_prop found, or error code in error case.
1219 *
1220 * @dt_alloc: An allocator that provides a virtual address to memory
1221 * for the resulting tree
1222 */
1223void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
1224{
1225    struct property *pp;
1226
1227    of_chosen = of_find_node_by_path("/chosen");
1228    if (of_chosen == NULL)
1229        of_chosen = of_find_node_by_path("/chosen@0");
1230    of_aliases = of_find_node_by_path("/aliases");
1231    if (!of_aliases)
1232        return;
1233
1234    for_each_property_of_node(of_aliases, pp) {
1235        const char *start = pp->name;
1236        const char *end = start + strlen(start);
1237        struct device_node *np;
1238        struct alias_prop *ap;
1239        int id, len;
1240
1241        /* Skip those we do not want to proceed */
1242        if (!strcmp(pp->name, "name") ||
1243            !strcmp(pp->name, "phandle") ||
1244            !strcmp(pp->name, "linux,phandle"))
1245            continue;
1246
1247        np = of_find_node_by_path(pp->value);
1248        if (!np)
1249            continue;
1250
1251        /* walk the alias backwards to extract the id and work out
1252         * the 'stem' string */
1253        while (isdigit(*(end-1)) && end > start)
1254            end--;
1255        len = end - start;
1256
1257        if (kstrtoint(end, 10, &id) < 0)
1258            continue;
1259
1260        /* Allocate an alias_prop with enough space for the stem */
1261        ap = dt_alloc(sizeof(*ap) + len + 1, 4);
1262        if (!ap)
1263            continue;
1264        ap->alias = start;
1265        of_alias_add(ap, np, id, start, len);
1266    }
1267}
1268
1269/**
1270 * of_alias_get_id - Get alias id for the given device_node
1271 * @np: Pointer to the given device_node
1272 * @stem: Alias stem of the given device_node
1273 *
1274 * The function travels the lookup table to get alias id for the given
1275 * device_node and alias stem. It returns the alias id if find it.
1276 */
1277int of_alias_get_id(struct device_node *np, const char *stem)
1278{
1279    struct alias_prop *app;
1280    int id = -ENODEV;
1281
1282    mutex_lock(&of_aliases_mutex);
1283    list_for_each_entry(app, &aliases_lookup, link) {
1284        if (strcmp(app->stem, stem) != 0)
1285            continue;
1286
1287        if (np == app->np) {
1288            id = app->id;
1289            break;
1290        }
1291    }
1292    mutex_unlock(&of_aliases_mutex);
1293
1294    return id;
1295}
1296EXPORT_SYMBOL_GPL(of_alias_get_id);
1297
1298const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
1299                   u32 *pu)
1300{
1301    const void *curv = cur;
1302
1303    if (!prop)
1304        return NULL;
1305
1306    if (!cur) {
1307        curv = prop->value;
1308        goto out_val;
1309    }
1310
1311    curv += sizeof(*cur);
1312    if (curv >= prop->value + prop->length)
1313        return NULL;
1314
1315out_val:
1316    *pu = be32_to_cpup(curv);
1317    return curv;
1318}
1319EXPORT_SYMBOL_GPL(of_prop_next_u32);
1320
1321const char *of_prop_next_string(struct property *prop, const char *cur)
1322{
1323    const void *curv = cur;
1324
1325    if (!prop)
1326        return NULL;
1327
1328    if (!cur)
1329        return prop->value;
1330
1331    curv += strlen(cur) + 1;
1332    if (curv >= prop->value + prop->length)
1333        return NULL;
1334
1335    return curv;
1336}
1337EXPORT_SYMBOL_GPL(of_prop_next_string);
1338

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