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v4.17
 
  1/*
  2 * libfdt - Flat Device Tree manipulation
  3 * Copyright (C) 2006 David Gibson, IBM Corporation.
  4 *
  5 * libfdt is dual licensed: you can use it either under the terms of
  6 * the GPL, or the BSD license, at your option.
  7 *
  8 *  a) This library is free software; you can redistribute it and/or
  9 *     modify it under the terms of the GNU General Public License as
 10 *     published by the Free Software Foundation; either version 2 of the
 11 *     License, or (at your option) any later version.
 12 *
 13 *     This library is distributed in the hope that it will be useful,
 14 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 15 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16 *     GNU General Public License for more details.
 17 *
 18 *     You should have received a copy of the GNU General Public
 19 *     License along with this library; if not, write to the Free
 20 *     Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 21 *     MA 02110-1301 USA
 22 *
 23 * Alternatively,
 24 *
 25 *  b) Redistribution and use in source and binary forms, with or
 26 *     without modification, are permitted provided that the following
 27 *     conditions are met:
 28 *
 29 *     1. Redistributions of source code must retain the above
 30 *        copyright notice, this list of conditions and the following
 31 *        disclaimer.
 32 *     2. Redistributions in binary form must reproduce the above
 33 *        copyright notice, this list of conditions and the following
 34 *        disclaimer in the documentation and/or other materials
 35 *        provided with the distribution.
 36 *
 37 *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 38 *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 39 *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 40 *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 41 *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 42 *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 43 *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 44 *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 45 *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 46 *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 47 *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 48 *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 49 *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 50 */
 51#include "libfdt_env.h"
 52
 53#include <fdt.h>
 54#include <libfdt.h>
 55
 56#include "libfdt_internal.h"
 57
 58static int fdt_nodename_eq_(const void *fdt, int offset,
 59			    const char *s, int len)
 60{
 61	int olen;
 62	const char *p = fdt_get_name(fdt, offset, &olen);
 63
 64	if (!p || olen < len)
 65		/* short match */
 66		return 0;
 67
 68	if (memcmp(p, s, len) != 0)
 69		return 0;
 70
 71	if (p[len] == '\0')
 72		return 1;
 73	else if (!memchr(s, '@', len) && (p[len] == '@'))
 74		return 1;
 75	else
 76		return 0;
 77}
 78
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 79const char *fdt_string(const void *fdt, int stroffset)
 80{
 81	return (const char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
 82}
 83
 84static int fdt_string_eq_(const void *fdt, int stroffset,
 85			  const char *s, int len)
 86{
 87	const char *p = fdt_string(fdt, stroffset);
 
 88
 89	return (strlen(p) == len) && (memcmp(p, s, len) == 0);
 90}
 91
 92uint32_t fdt_get_max_phandle(const void *fdt)
 93{
 94	uint32_t max_phandle = 0;
 95	int offset;
 96
 97	for (offset = fdt_next_node(fdt, -1, NULL);;
 98	     offset = fdt_next_node(fdt, offset, NULL)) {
 99		uint32_t phandle;
100
101		if (offset == -FDT_ERR_NOTFOUND)
102			return max_phandle;
 
 
103
104		if (offset < 0)
105			return (uint32_t)-1;
106
107		phandle = fdt_get_phandle(fdt, offset);
108		if (phandle == (uint32_t)-1)
109			continue;
110
111		if (phandle > max_phandle)
112			max_phandle = phandle;
113	}
114
 
 
 
115	return 0;
116}
117
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
118int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
119{
120	FDT_CHECK_HEADER(fdt);
121	*address = fdt64_to_cpu(fdt_mem_rsv_(fdt, n)->address);
122	*size = fdt64_to_cpu(fdt_mem_rsv_(fdt, n)->size);
 
 
 
 
 
 
123	return 0;
124}
125
126int fdt_num_mem_rsv(const void *fdt)
127{
128	int i = 0;
 
129
130	while (fdt64_to_cpu(fdt_mem_rsv_(fdt, i)->size) != 0)
131		i++;
132	return i;
 
 
133}
134
135static int nextprop_(const void *fdt, int offset)
136{
137	uint32_t tag;
138	int nextoffset;
139
140	do {
141		tag = fdt_next_tag(fdt, offset, &nextoffset);
142
143		switch (tag) {
144		case FDT_END:
145			if (nextoffset >= 0)
146				return -FDT_ERR_BADSTRUCTURE;
147			else
148				return nextoffset;
149
150		case FDT_PROP:
151			return offset;
152		}
153		offset = nextoffset;
154	} while (tag == FDT_NOP);
155
156	return -FDT_ERR_NOTFOUND;
157}
158
159int fdt_subnode_offset_namelen(const void *fdt, int offset,
160			       const char *name, int namelen)
161{
162	int depth;
163
164	FDT_CHECK_HEADER(fdt);
165
166	for (depth = 0;
167	     (offset >= 0) && (depth >= 0);
168	     offset = fdt_next_node(fdt, offset, &depth))
169		if ((depth == 1)
170		    && fdt_nodename_eq_(fdt, offset, name, namelen))
171			return offset;
172
173	if (depth < 0)
174		return -FDT_ERR_NOTFOUND;
175	return offset; /* error */
176}
177
178int fdt_subnode_offset(const void *fdt, int parentoffset,
179		       const char *name)
180{
181	return fdt_subnode_offset_namelen(fdt, parentoffset, name, strlen(name));
182}
183
184int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
185{
186	const char *end = path + namelen;
187	const char *p = path;
188	int offset = 0;
189
190	FDT_CHECK_HEADER(fdt);
191
192	/* see if we have an alias */
193	if (*path != '/') {
194		const char *q = memchr(path, '/', end - p);
195
196		if (!q)
197			q = end;
198
199		p = fdt_get_alias_namelen(fdt, p, q - p);
200		if (!p)
201			return -FDT_ERR_BADPATH;
202		offset = fdt_path_offset(fdt, p);
203
204		p = q;
205	}
206
207	while (p < end) {
208		const char *q;
209
210		while (*p == '/') {
211			p++;
212			if (p == end)
213				return offset;
214		}
215		q = memchr(p, '/', end - p);
216		if (! q)
217			q = end;
218
219		offset = fdt_subnode_offset_namelen(fdt, offset, p, q-p);
220		if (offset < 0)
221			return offset;
222
223		p = q;
224	}
225
226	return offset;
227}
228
229int fdt_path_offset(const void *fdt, const char *path)
230{
231	return fdt_path_offset_namelen(fdt, path, strlen(path));
232}
233
234const char *fdt_get_name(const void *fdt, int nodeoffset, int *len)
235{
236	const struct fdt_node_header *nh = fdt_offset_ptr_(fdt, nodeoffset);
237	const char *nameptr;
238	int err;
239
240	if (((err = fdt_check_header(fdt)) != 0)
241	    || ((err = fdt_check_node_offset_(fdt, nodeoffset)) < 0))
242			goto fail;
243
244	nameptr = nh->name;
245
246	if (fdt_version(fdt) < 0x10) {
247		/*
248		 * For old FDT versions, match the naming conventions of V16:
249		 * give only the leaf name (after all /). The actual tree
250		 * contents are loosely checked.
251		 */
252		const char *leaf;
253		leaf = strrchr(nameptr, '/');
254		if (leaf == NULL) {
255			err = -FDT_ERR_BADSTRUCTURE;
256			goto fail;
257		}
258		nameptr = leaf+1;
259	}
260
261	if (len)
262		*len = strlen(nameptr);
263
264	return nameptr;
265
266 fail:
267	if (len)
268		*len = err;
269	return NULL;
270}
271
272int fdt_first_property_offset(const void *fdt, int nodeoffset)
273{
274	int offset;
275
276	if ((offset = fdt_check_node_offset_(fdt, nodeoffset)) < 0)
277		return offset;
278
279	return nextprop_(fdt, offset);
280}
281
282int fdt_next_property_offset(const void *fdt, int offset)
283{
284	if ((offset = fdt_check_prop_offset_(fdt, offset)) < 0)
285		return offset;
286
287	return nextprop_(fdt, offset);
288}
289
290static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
291						              int offset,
292						              int *lenp)
293{
294	int err;
295	const struct fdt_property *prop;
296
297	if ((err = fdt_check_prop_offset_(fdt, offset)) < 0) {
 
298		if (lenp)
299			*lenp = err;
300		return NULL;
301	}
302
303	prop = fdt_offset_ptr_(fdt, offset);
304
305	if (lenp)
306		*lenp = fdt32_to_cpu(prop->len);
307
308	return prop;
309}
310
311const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
312						      int offset,
313						      int *lenp)
314{
315	/* Prior to version 16, properties may need realignment
316	 * and this API does not work. fdt_getprop_*() will, however. */
317
318	if (fdt_version(fdt) < 0x10) {
319		if (lenp)
320			*lenp = -FDT_ERR_BADVERSION;
321		return NULL;
322	}
323
324	return fdt_get_property_by_offset_(fdt, offset, lenp);
325}
326
327static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
328						            int offset,
329						            const char *name,
330						            int namelen,
331							    int *lenp,
332							    int *poffset)
333{
334	for (offset = fdt_first_property_offset(fdt, offset);
335	     (offset >= 0);
336	     (offset = fdt_next_property_offset(fdt, offset))) {
337		const struct fdt_property *prop;
338
339		if (!(prop = fdt_get_property_by_offset_(fdt, offset, lenp))) {
 
340			offset = -FDT_ERR_INTERNAL;
341			break;
342		}
343		if (fdt_string_eq_(fdt, fdt32_to_cpu(prop->nameoff),
344				   name, namelen)) {
345			if (poffset)
346				*poffset = offset;
347			return prop;
348		}
349	}
350
351	if (lenp)
352		*lenp = offset;
353	return NULL;
354}
355
356
357const struct fdt_property *fdt_get_property_namelen(const void *fdt,
358						    int offset,
359						    const char *name,
360						    int namelen, int *lenp)
361{
362	/* Prior to version 16, properties may need realignment
363	 * and this API does not work. fdt_getprop_*() will, however. */
364	if (fdt_version(fdt) < 0x10) {
365		if (lenp)
366			*lenp = -FDT_ERR_BADVERSION;
367		return NULL;
368	}
369
370	return fdt_get_property_namelen_(fdt, offset, name, namelen, lenp,
371					 NULL);
372}
373
374
375const struct fdt_property *fdt_get_property(const void *fdt,
376					    int nodeoffset,
377					    const char *name, int *lenp)
378{
379	return fdt_get_property_namelen(fdt, nodeoffset, name,
380					strlen(name), lenp);
381}
382
383const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
384				const char *name, int namelen, int *lenp)
385{
386	int poffset;
387	const struct fdt_property *prop;
388
389	prop = fdt_get_property_namelen_(fdt, nodeoffset, name, namelen, lenp,
390					 &poffset);
391	if (!prop)
392		return NULL;
393
394	/* Handle realignment */
395	if (fdt_version(fdt) < 0x10 && (poffset + sizeof(*prop)) % 8 &&
396	    fdt32_to_cpu(prop->len) >= 8)
397		return prop->data + 4;
398	return prop->data;
399}
400
401const void *fdt_getprop_by_offset(const void *fdt, int offset,
402				  const char **namep, int *lenp)
403{
404	const struct fdt_property *prop;
405
406	prop = fdt_get_property_by_offset_(fdt, offset, lenp);
407	if (!prop)
408		return NULL;
409	if (namep)
410		*namep = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
411
412	/* Handle realignment */
413	if (fdt_version(fdt) < 0x10 && (offset + sizeof(*prop)) % 8 &&
414	    fdt32_to_cpu(prop->len) >= 8)
415		return prop->data + 4;
416	return prop->data;
417}
418
419const void *fdt_getprop(const void *fdt, int nodeoffset,
420			const char *name, int *lenp)
421{
422	return fdt_getprop_namelen(fdt, nodeoffset, name, strlen(name), lenp);
423}
424
425uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
426{
427	const fdt32_t *php;
428	int len;
429
430	/* FIXME: This is a bit sub-optimal, since we potentially scan
431	 * over all the properties twice. */
432	php = fdt_getprop(fdt, nodeoffset, "phandle", &len);
433	if (!php || (len != sizeof(*php))) {
434		php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
435		if (!php || (len != sizeof(*php)))
436			return 0;
437	}
438
439	return fdt32_to_cpu(*php);
440}
441
442const char *fdt_get_alias_namelen(const void *fdt,
443				  const char *name, int namelen)
444{
445	int aliasoffset;
446
447	aliasoffset = fdt_path_offset(fdt, "/aliases");
448	if (aliasoffset < 0)
449		return NULL;
450
451	return fdt_getprop_namelen(fdt, aliasoffset, name, namelen, NULL);
452}
453
454const char *fdt_get_alias(const void *fdt, const char *name)
455{
456	return fdt_get_alias_namelen(fdt, name, strlen(name));
457}
458
459int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen)
460{
461	int pdepth = 0, p = 0;
462	int offset, depth, namelen;
463	const char *name;
464
465	FDT_CHECK_HEADER(fdt);
466
467	if (buflen < 2)
468		return -FDT_ERR_NOSPACE;
469
470	for (offset = 0, depth = 0;
471	     (offset >= 0) && (offset <= nodeoffset);
472	     offset = fdt_next_node(fdt, offset, &depth)) {
473		while (pdepth > depth) {
474			do {
475				p--;
476			} while (buf[p-1] != '/');
477			pdepth--;
478		}
479
480		if (pdepth >= depth) {
481			name = fdt_get_name(fdt, offset, &namelen);
482			if (!name)
483				return namelen;
484			if ((p + namelen + 1) <= buflen) {
485				memcpy(buf + p, name, namelen);
486				p += namelen;
487				buf[p++] = '/';
488				pdepth++;
489			}
490		}
491
492		if (offset == nodeoffset) {
493			if (pdepth < (depth + 1))
494				return -FDT_ERR_NOSPACE;
495
496			if (p > 1) /* special case so that root path is "/", not "" */
497				p--;
498			buf[p] = '\0';
499			return 0;
500		}
501	}
502
503	if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
504		return -FDT_ERR_BADOFFSET;
505	else if (offset == -FDT_ERR_BADOFFSET)
506		return -FDT_ERR_BADSTRUCTURE;
507
508	return offset; /* error from fdt_next_node() */
509}
510
511int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
512				 int supernodedepth, int *nodedepth)
513{
514	int offset, depth;
515	int supernodeoffset = -FDT_ERR_INTERNAL;
516
517	FDT_CHECK_HEADER(fdt);
518
519	if (supernodedepth < 0)
520		return -FDT_ERR_NOTFOUND;
521
522	for (offset = 0, depth = 0;
523	     (offset >= 0) && (offset <= nodeoffset);
524	     offset = fdt_next_node(fdt, offset, &depth)) {
525		if (depth == supernodedepth)
526			supernodeoffset = offset;
527
528		if (offset == nodeoffset) {
529			if (nodedepth)
530				*nodedepth = depth;
531
532			if (supernodedepth > depth)
533				return -FDT_ERR_NOTFOUND;
534			else
535				return supernodeoffset;
536		}
537	}
538
539	if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
540		return -FDT_ERR_BADOFFSET;
541	else if (offset == -FDT_ERR_BADOFFSET)
542		return -FDT_ERR_BADSTRUCTURE;
 
 
543
544	return offset; /* error from fdt_next_node() */
545}
546
547int fdt_node_depth(const void *fdt, int nodeoffset)
548{
549	int nodedepth;
550	int err;
551
552	err = fdt_supernode_atdepth_offset(fdt, nodeoffset, 0, &nodedepth);
553	if (err)
554		return (err < 0) ? err : -FDT_ERR_INTERNAL;
 
555	return nodedepth;
556}
557
558int fdt_parent_offset(const void *fdt, int nodeoffset)
559{
560	int nodedepth = fdt_node_depth(fdt, nodeoffset);
561
562	if (nodedepth < 0)
563		return nodedepth;
564	return fdt_supernode_atdepth_offset(fdt, nodeoffset,
565					    nodedepth - 1, NULL);
566}
567
568int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
569				  const char *propname,
570				  const void *propval, int proplen)
571{
572	int offset;
573	const void *val;
574	int len;
575
576	FDT_CHECK_HEADER(fdt);
577
578	/* FIXME: The algorithm here is pretty horrible: we scan each
579	 * property of a node in fdt_getprop(), then if that didn't
580	 * find what we want, we scan over them again making our way
581	 * to the next node.  Still it's the easiest to implement
582	 * approach; performance can come later. */
583	for (offset = fdt_next_node(fdt, startoffset, NULL);
584	     offset >= 0;
585	     offset = fdt_next_node(fdt, offset, NULL)) {
586		val = fdt_getprop(fdt, offset, propname, &len);
587		if (val && (len == proplen)
588		    && (memcmp(val, propval, len) == 0))
589			return offset;
590	}
591
592	return offset; /* error from fdt_next_node() */
593}
594
595int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
596{
597	int offset;
598
599	if ((phandle == 0) || (phandle == -1))
600		return -FDT_ERR_BADPHANDLE;
601
602	FDT_CHECK_HEADER(fdt);
603
604	/* FIXME: The algorithm here is pretty horrible: we
605	 * potentially scan each property of a node in
606	 * fdt_get_phandle(), then if that didn't find what
607	 * we want, we scan over them again making our way to the next
608	 * node.  Still it's the easiest to implement approach;
609	 * performance can come later. */
610	for (offset = fdt_next_node(fdt, -1, NULL);
611	     offset >= 0;
612	     offset = fdt_next_node(fdt, offset, NULL)) {
613		if (fdt_get_phandle(fdt, offset) == phandle)
614			return offset;
615	}
616
617	return offset; /* error from fdt_next_node() */
618}
619
620int fdt_stringlist_contains(const char *strlist, int listlen, const char *str)
621{
622	int len = strlen(str);
623	const char *p;
624
625	while (listlen >= len) {
626		if (memcmp(str, strlist, len+1) == 0)
627			return 1;
628		p = memchr(strlist, '\0', listlen);
629		if (!p)
630			return 0; /* malformed strlist.. */
631		listlen -= (p-strlist) + 1;
632		strlist = p + 1;
633	}
634	return 0;
635}
636
637int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property)
638{
639	const char *list, *end;
640	int length, count = 0;
641
642	list = fdt_getprop(fdt, nodeoffset, property, &length);
643	if (!list)
644		return length;
645
646	end = list + length;
647
648	while (list < end) {
649		length = strnlen(list, end - list) + 1;
650
651		/* Abort if the last string isn't properly NUL-terminated. */
652		if (list + length > end)
653			return -FDT_ERR_BADVALUE;
654
655		list += length;
656		count++;
657	}
658
659	return count;
660}
661
662int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property,
663			  const char *string)
664{
665	int length, len, idx = 0;
666	const char *list, *end;
667
668	list = fdt_getprop(fdt, nodeoffset, property, &length);
669	if (!list)
670		return length;
671
672	len = strlen(string) + 1;
673	end = list + length;
674
675	while (list < end) {
676		length = strnlen(list, end - list) + 1;
677
678		/* Abort if the last string isn't properly NUL-terminated. */
679		if (list + length > end)
680			return -FDT_ERR_BADVALUE;
681
682		if (length == len && memcmp(list, string, length) == 0)
683			return idx;
684
685		list += length;
686		idx++;
687	}
688
689	return -FDT_ERR_NOTFOUND;
690}
691
692const char *fdt_stringlist_get(const void *fdt, int nodeoffset,
693			       const char *property, int idx,
694			       int *lenp)
695{
696	const char *list, *end;
697	int length;
698
699	list = fdt_getprop(fdt, nodeoffset, property, &length);
700	if (!list) {
701		if (lenp)
702			*lenp = length;
703
704		return NULL;
705	}
706
707	end = list + length;
708
709	while (list < end) {
710		length = strnlen(list, end - list) + 1;
711
712		/* Abort if the last string isn't properly NUL-terminated. */
713		if (list + length > end) {
714			if (lenp)
715				*lenp = -FDT_ERR_BADVALUE;
716
717			return NULL;
718		}
719
720		if (idx == 0) {
721			if (lenp)
722				*lenp = length - 1;
723
724			return list;
725		}
726
727		list += length;
728		idx--;
729	}
730
731	if (lenp)
732		*lenp = -FDT_ERR_NOTFOUND;
733
734	return NULL;
735}
736
737int fdt_node_check_compatible(const void *fdt, int nodeoffset,
738			      const char *compatible)
739{
740	const void *prop;
741	int len;
742
743	prop = fdt_getprop(fdt, nodeoffset, "compatible", &len);
744	if (!prop)
745		return len;
746
747	return !fdt_stringlist_contains(prop, len, compatible);
748}
749
750int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
751				  const char *compatible)
752{
753	int offset, err;
754
755	FDT_CHECK_HEADER(fdt);
756
757	/* FIXME: The algorithm here is pretty horrible: we scan each
758	 * property of a node in fdt_node_check_compatible(), then if
759	 * that didn't find what we want, we scan over them again
760	 * making our way to the next node.  Still it's the easiest to
761	 * implement approach; performance can come later. */
762	for (offset = fdt_next_node(fdt, startoffset, NULL);
763	     offset >= 0;
764	     offset = fdt_next_node(fdt, offset, NULL)) {
765		err = fdt_node_check_compatible(fdt, offset, compatible);
766		if ((err < 0) && (err != -FDT_ERR_NOTFOUND))
767			return err;
768		else if (err == 0)
769			return offset;
770	}
771
772	return offset; /* error from fdt_next_node() */
773}
v6.8
  1// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
  2/*
  3 * libfdt - Flat Device Tree manipulation
  4 * Copyright (C) 2006 David Gibson, IBM Corporation.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  5 */
  6#include "libfdt_env.h"
  7
  8#include <fdt.h>
  9#include <libfdt.h>
 10
 11#include "libfdt_internal.h"
 12
 13static int fdt_nodename_eq_(const void *fdt, int offset,
 14			    const char *s, int len)
 15{
 16	int olen;
 17	const char *p = fdt_get_name(fdt, offset, &olen);
 18
 19	if (!p || olen < len)
 20		/* short match */
 21		return 0;
 22
 23	if (memcmp(p, s, len) != 0)
 24		return 0;
 25
 26	if (p[len] == '\0')
 27		return 1;
 28	else if (!memchr(s, '@', len) && (p[len] == '@'))
 29		return 1;
 30	else
 31		return 0;
 32}
 33
 34const char *fdt_get_string(const void *fdt, int stroffset, int *lenp)
 35{
 36	int32_t totalsize;
 37	uint32_t absoffset;
 38	size_t len;
 39	int err;
 40	const char *s, *n;
 41
 42	if (can_assume(VALID_INPUT)) {
 43		s = (const char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
 44
 45		if (lenp)
 46			*lenp = strlen(s);
 47		return s;
 48	}
 49	totalsize = fdt_ro_probe_(fdt);
 50	err = totalsize;
 51	if (totalsize < 0)
 52		goto fail;
 53
 54	err = -FDT_ERR_BADOFFSET;
 55	absoffset = stroffset + fdt_off_dt_strings(fdt);
 56	if (absoffset >= (unsigned)totalsize)
 57		goto fail;
 58	len = totalsize - absoffset;
 59
 60	if (fdt_magic(fdt) == FDT_MAGIC) {
 61		if (stroffset < 0)
 62			goto fail;
 63		if (can_assume(LATEST) || fdt_version(fdt) >= 17) {
 64			if ((unsigned)stroffset >= fdt_size_dt_strings(fdt))
 65				goto fail;
 66			if ((fdt_size_dt_strings(fdt) - stroffset) < len)
 67				len = fdt_size_dt_strings(fdt) - stroffset;
 68		}
 69	} else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
 70		unsigned int sw_stroffset = -stroffset;
 71
 72		if ((stroffset >= 0) ||
 73		    (sw_stroffset > fdt_size_dt_strings(fdt)))
 74			goto fail;
 75		if (sw_stroffset < len)
 76			len = sw_stroffset;
 77	} else {
 78		err = -FDT_ERR_INTERNAL;
 79		goto fail;
 80	}
 81
 82	s = (const char *)fdt + absoffset;
 83	n = memchr(s, '\0', len);
 84	if (!n) {
 85		/* missing terminating NULL */
 86		err = -FDT_ERR_TRUNCATED;
 87		goto fail;
 88	}
 89
 90	if (lenp)
 91		*lenp = n - s;
 92	return s;
 93
 94fail:
 95	if (lenp)
 96		*lenp = err;
 97	return NULL;
 98}
 99
100const char *fdt_string(const void *fdt, int stroffset)
101{
102	return fdt_get_string(fdt, stroffset, NULL);
103}
104
105static int fdt_string_eq_(const void *fdt, int stroffset,
106			  const char *s, int len)
107{
108	int slen;
109	const char *p = fdt_get_string(fdt, stroffset, &slen);
110
111	return p && (slen == len) && (memcmp(p, s, len) == 0);
112}
113
114int fdt_find_max_phandle(const void *fdt, uint32_t *phandle)
115{
116	uint32_t max = 0;
117	int offset = -1;
118
119	while (true) {
120		uint32_t value;
 
121
122		offset = fdt_next_node(fdt, offset, NULL);
123		if (offset < 0) {
124			if (offset == -FDT_ERR_NOTFOUND)
125				break;
126
127			return offset;
128		}
129
130		value = fdt_get_phandle(fdt, offset);
 
 
131
132		if (value > max)
133			max = value;
134	}
135
136	if (phandle)
137		*phandle = max;
138
139	return 0;
140}
141
142int fdt_generate_phandle(const void *fdt, uint32_t *phandle)
143{
144	uint32_t max;
145	int err;
146
147	err = fdt_find_max_phandle(fdt, &max);
148	if (err < 0)
149		return err;
150
151	if (max == FDT_MAX_PHANDLE)
152		return -FDT_ERR_NOPHANDLES;
153
154	if (phandle)
155		*phandle = max + 1;
156
157	return 0;
158}
159
160static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
161{
162	unsigned int offset = n * sizeof(struct fdt_reserve_entry);
163	unsigned int absoffset = fdt_off_mem_rsvmap(fdt) + offset;
164
165	if (!can_assume(VALID_INPUT)) {
166		if (absoffset < fdt_off_mem_rsvmap(fdt))
167			return NULL;
168		if (absoffset > fdt_totalsize(fdt) -
169		    sizeof(struct fdt_reserve_entry))
170			return NULL;
171	}
172	return fdt_mem_rsv_(fdt, n);
173}
174
175int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
176{
177	const struct fdt_reserve_entry *re;
178
179	FDT_RO_PROBE(fdt);
180	re = fdt_mem_rsv(fdt, n);
181	if (!can_assume(VALID_INPUT) && !re)
182		return -FDT_ERR_BADOFFSET;
183
184	*address = fdt64_ld_(&re->address);
185	*size = fdt64_ld_(&re->size);
186	return 0;
187}
188
189int fdt_num_mem_rsv(const void *fdt)
190{
191	int i;
192	const struct fdt_reserve_entry *re;
193
194	for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
195		if (fdt64_ld_(&re->size) == 0)
196			return i;
197	}
198	return -FDT_ERR_TRUNCATED;
199}
200
201static int nextprop_(const void *fdt, int offset)
202{
203	uint32_t tag;
204	int nextoffset;
205
206	do {
207		tag = fdt_next_tag(fdt, offset, &nextoffset);
208
209		switch (tag) {
210		case FDT_END:
211			if (nextoffset >= 0)
212				return -FDT_ERR_BADSTRUCTURE;
213			else
214				return nextoffset;
215
216		case FDT_PROP:
217			return offset;
218		}
219		offset = nextoffset;
220	} while (tag == FDT_NOP);
221
222	return -FDT_ERR_NOTFOUND;
223}
224
225int fdt_subnode_offset_namelen(const void *fdt, int offset,
226			       const char *name, int namelen)
227{
228	int depth;
229
230	FDT_RO_PROBE(fdt);
231
232	for (depth = 0;
233	     (offset >= 0) && (depth >= 0);
234	     offset = fdt_next_node(fdt, offset, &depth))
235		if ((depth == 1)
236		    && fdt_nodename_eq_(fdt, offset, name, namelen))
237			return offset;
238
239	if (depth < 0)
240		return -FDT_ERR_NOTFOUND;
241	return offset; /* error */
242}
243
244int fdt_subnode_offset(const void *fdt, int parentoffset,
245		       const char *name)
246{
247	return fdt_subnode_offset_namelen(fdt, parentoffset, name, strlen(name));
248}
249
250int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
251{
252	const char *end = path + namelen;
253	const char *p = path;
254	int offset = 0;
255
256	FDT_RO_PROBE(fdt);
257
258	/* see if we have an alias */
259	if (*path != '/') {
260		const char *q = memchr(path, '/', end - p);
261
262		if (!q)
263			q = end;
264
265		p = fdt_get_alias_namelen(fdt, p, q - p);
266		if (!p)
267			return -FDT_ERR_BADPATH;
268		offset = fdt_path_offset(fdt, p);
269
270		p = q;
271	}
272
273	while (p < end) {
274		const char *q;
275
276		while (*p == '/') {
277			p++;
278			if (p == end)
279				return offset;
280		}
281		q = memchr(p, '/', end - p);
282		if (! q)
283			q = end;
284
285		offset = fdt_subnode_offset_namelen(fdt, offset, p, q-p);
286		if (offset < 0)
287			return offset;
288
289		p = q;
290	}
291
292	return offset;
293}
294
295int fdt_path_offset(const void *fdt, const char *path)
296{
297	return fdt_path_offset_namelen(fdt, path, strlen(path));
298}
299
300const char *fdt_get_name(const void *fdt, int nodeoffset, int *len)
301{
302	const struct fdt_node_header *nh = fdt_offset_ptr_(fdt, nodeoffset);
303	const char *nameptr;
304	int err;
305
306	if (((err = fdt_ro_probe_(fdt)) < 0)
307	    || ((err = fdt_check_node_offset_(fdt, nodeoffset)) < 0))
308			goto fail;
309
310	nameptr = nh->name;
311
312	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
313		/*
314		 * For old FDT versions, match the naming conventions of V16:
315		 * give only the leaf name (after all /). The actual tree
316		 * contents are loosely checked.
317		 */
318		const char *leaf;
319		leaf = strrchr(nameptr, '/');
320		if (leaf == NULL) {
321			err = -FDT_ERR_BADSTRUCTURE;
322			goto fail;
323		}
324		nameptr = leaf+1;
325	}
326
327	if (len)
328		*len = strlen(nameptr);
329
330	return nameptr;
331
332 fail:
333	if (len)
334		*len = err;
335	return NULL;
336}
337
338int fdt_first_property_offset(const void *fdt, int nodeoffset)
339{
340	int offset;
341
342	if ((offset = fdt_check_node_offset_(fdt, nodeoffset)) < 0)
343		return offset;
344
345	return nextprop_(fdt, offset);
346}
347
348int fdt_next_property_offset(const void *fdt, int offset)
349{
350	if ((offset = fdt_check_prop_offset_(fdt, offset)) < 0)
351		return offset;
352
353	return nextprop_(fdt, offset);
354}
355
356static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
357						              int offset,
358						              int *lenp)
359{
360	int err;
361	const struct fdt_property *prop;
362
363	if (!can_assume(VALID_INPUT) &&
364	    (err = fdt_check_prop_offset_(fdt, offset)) < 0) {
365		if (lenp)
366			*lenp = err;
367		return NULL;
368	}
369
370	prop = fdt_offset_ptr_(fdt, offset);
371
372	if (lenp)
373		*lenp = fdt32_ld_(&prop->len);
374
375	return prop;
376}
377
378const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
379						      int offset,
380						      int *lenp)
381{
382	/* Prior to version 16, properties may need realignment
383	 * and this API does not work. fdt_getprop_*() will, however. */
384
385	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
386		if (lenp)
387			*lenp = -FDT_ERR_BADVERSION;
388		return NULL;
389	}
390
391	return fdt_get_property_by_offset_(fdt, offset, lenp);
392}
393
394static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
395						            int offset,
396						            const char *name,
397						            int namelen,
398							    int *lenp,
399							    int *poffset)
400{
401	for (offset = fdt_first_property_offset(fdt, offset);
402	     (offset >= 0);
403	     (offset = fdt_next_property_offset(fdt, offset))) {
404		const struct fdt_property *prop;
405
406		prop = fdt_get_property_by_offset_(fdt, offset, lenp);
407		if (!can_assume(LIBFDT_FLAWLESS) && !prop) {
408			offset = -FDT_ERR_INTERNAL;
409			break;
410		}
411		if (fdt_string_eq_(fdt, fdt32_ld_(&prop->nameoff),
412				   name, namelen)) {
413			if (poffset)
414				*poffset = offset;
415			return prop;
416		}
417	}
418
419	if (lenp)
420		*lenp = offset;
421	return NULL;
422}
423
424
425const struct fdt_property *fdt_get_property_namelen(const void *fdt,
426						    int offset,
427						    const char *name,
428						    int namelen, int *lenp)
429{
430	/* Prior to version 16, properties may need realignment
431	 * and this API does not work. fdt_getprop_*() will, however. */
432	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
433		if (lenp)
434			*lenp = -FDT_ERR_BADVERSION;
435		return NULL;
436	}
437
438	return fdt_get_property_namelen_(fdt, offset, name, namelen, lenp,
439					 NULL);
440}
441
442
443const struct fdt_property *fdt_get_property(const void *fdt,
444					    int nodeoffset,
445					    const char *name, int *lenp)
446{
447	return fdt_get_property_namelen(fdt, nodeoffset, name,
448					strlen(name), lenp);
449}
450
451const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
452				const char *name, int namelen, int *lenp)
453{
454	int poffset;
455	const struct fdt_property *prop;
456
457	prop = fdt_get_property_namelen_(fdt, nodeoffset, name, namelen, lenp,
458					 &poffset);
459	if (!prop)
460		return NULL;
461
462	/* Handle realignment */
463	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 &&
464	    (poffset + sizeof(*prop)) % 8 && fdt32_ld_(&prop->len) >= 8)
465		return prop->data + 4;
466	return prop->data;
467}
468
469const void *fdt_getprop_by_offset(const void *fdt, int offset,
470				  const char **namep, int *lenp)
471{
472	const struct fdt_property *prop;
473
474	prop = fdt_get_property_by_offset_(fdt, offset, lenp);
475	if (!prop)
476		return NULL;
477	if (namep) {
478		const char *name;
479		int namelen;
480
481		if (!can_assume(VALID_INPUT)) {
482			name = fdt_get_string(fdt, fdt32_ld_(&prop->nameoff),
483					      &namelen);
484			*namep = name;
485			if (!name) {
486				if (lenp)
487					*lenp = namelen;
488				return NULL;
489			}
490		} else {
491			*namep = fdt_string(fdt, fdt32_ld_(&prop->nameoff));
492		}
493	}
494
495	/* Handle realignment */
496	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 &&
497	    (offset + sizeof(*prop)) % 8 && fdt32_ld_(&prop->len) >= 8)
498		return prop->data + 4;
499	return prop->data;
500}
501
502const void *fdt_getprop(const void *fdt, int nodeoffset,
503			const char *name, int *lenp)
504{
505	return fdt_getprop_namelen(fdt, nodeoffset, name, strlen(name), lenp);
506}
507
508uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
509{
510	const fdt32_t *php;
511	int len;
512
513	/* FIXME: This is a bit sub-optimal, since we potentially scan
514	 * over all the properties twice. */
515	php = fdt_getprop(fdt, nodeoffset, "phandle", &len);
516	if (!php || (len != sizeof(*php))) {
517		php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
518		if (!php || (len != sizeof(*php)))
519			return 0;
520	}
521
522	return fdt32_ld_(php);
523}
524
525const char *fdt_get_alias_namelen(const void *fdt,
526				  const char *name, int namelen)
527{
528	int aliasoffset;
529
530	aliasoffset = fdt_path_offset(fdt, "/aliases");
531	if (aliasoffset < 0)
532		return NULL;
533
534	return fdt_getprop_namelen(fdt, aliasoffset, name, namelen, NULL);
535}
536
537const char *fdt_get_alias(const void *fdt, const char *name)
538{
539	return fdt_get_alias_namelen(fdt, name, strlen(name));
540}
541
542int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen)
543{
544	int pdepth = 0, p = 0;
545	int offset, depth, namelen;
546	const char *name;
547
548	FDT_RO_PROBE(fdt);
549
550	if (buflen < 2)
551		return -FDT_ERR_NOSPACE;
552
553	for (offset = 0, depth = 0;
554	     (offset >= 0) && (offset <= nodeoffset);
555	     offset = fdt_next_node(fdt, offset, &depth)) {
556		while (pdepth > depth) {
557			do {
558				p--;
559			} while (buf[p-1] != '/');
560			pdepth--;
561		}
562
563		if (pdepth >= depth) {
564			name = fdt_get_name(fdt, offset, &namelen);
565			if (!name)
566				return namelen;
567			if ((p + namelen + 1) <= buflen) {
568				memcpy(buf + p, name, namelen);
569				p += namelen;
570				buf[p++] = '/';
571				pdepth++;
572			}
573		}
574
575		if (offset == nodeoffset) {
576			if (pdepth < (depth + 1))
577				return -FDT_ERR_NOSPACE;
578
579			if (p > 1) /* special case so that root path is "/", not "" */
580				p--;
581			buf[p] = '\0';
582			return 0;
583		}
584	}
585
586	if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
587		return -FDT_ERR_BADOFFSET;
588	else if (offset == -FDT_ERR_BADOFFSET)
589		return -FDT_ERR_BADSTRUCTURE;
590
591	return offset; /* error from fdt_next_node() */
592}
593
594int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
595				 int supernodedepth, int *nodedepth)
596{
597	int offset, depth;
598	int supernodeoffset = -FDT_ERR_INTERNAL;
599
600	FDT_RO_PROBE(fdt);
601
602	if (supernodedepth < 0)
603		return -FDT_ERR_NOTFOUND;
604
605	for (offset = 0, depth = 0;
606	     (offset >= 0) && (offset <= nodeoffset);
607	     offset = fdt_next_node(fdt, offset, &depth)) {
608		if (depth == supernodedepth)
609			supernodeoffset = offset;
610
611		if (offset == nodeoffset) {
612			if (nodedepth)
613				*nodedepth = depth;
614
615			if (supernodedepth > depth)
616				return -FDT_ERR_NOTFOUND;
617			else
618				return supernodeoffset;
619		}
620	}
621
622	if (!can_assume(VALID_INPUT)) {
623		if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
624			return -FDT_ERR_BADOFFSET;
625		else if (offset == -FDT_ERR_BADOFFSET)
626			return -FDT_ERR_BADSTRUCTURE;
627	}
628
629	return offset; /* error from fdt_next_node() */
630}
631
632int fdt_node_depth(const void *fdt, int nodeoffset)
633{
634	int nodedepth;
635	int err;
636
637	err = fdt_supernode_atdepth_offset(fdt, nodeoffset, 0, &nodedepth);
638	if (err)
639		return (can_assume(LIBFDT_FLAWLESS) || err < 0) ? err :
640			-FDT_ERR_INTERNAL;
641	return nodedepth;
642}
643
644int fdt_parent_offset(const void *fdt, int nodeoffset)
645{
646	int nodedepth = fdt_node_depth(fdt, nodeoffset);
647
648	if (nodedepth < 0)
649		return nodedepth;
650	return fdt_supernode_atdepth_offset(fdt, nodeoffset,
651					    nodedepth - 1, NULL);
652}
653
654int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
655				  const char *propname,
656				  const void *propval, int proplen)
657{
658	int offset;
659	const void *val;
660	int len;
661
662	FDT_RO_PROBE(fdt);
663
664	/* FIXME: The algorithm here is pretty horrible: we scan each
665	 * property of a node in fdt_getprop(), then if that didn't
666	 * find what we want, we scan over them again making our way
667	 * to the next node.  Still it's the easiest to implement
668	 * approach; performance can come later. */
669	for (offset = fdt_next_node(fdt, startoffset, NULL);
670	     offset >= 0;
671	     offset = fdt_next_node(fdt, offset, NULL)) {
672		val = fdt_getprop(fdt, offset, propname, &len);
673		if (val && (len == proplen)
674		    && (memcmp(val, propval, len) == 0))
675			return offset;
676	}
677
678	return offset; /* error from fdt_next_node() */
679}
680
681int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
682{
683	int offset;
684
685	if ((phandle == 0) || (phandle == ~0U))
686		return -FDT_ERR_BADPHANDLE;
687
688	FDT_RO_PROBE(fdt);
689
690	/* FIXME: The algorithm here is pretty horrible: we
691	 * potentially scan each property of a node in
692	 * fdt_get_phandle(), then if that didn't find what
693	 * we want, we scan over them again making our way to the next
694	 * node.  Still it's the easiest to implement approach;
695	 * performance can come later. */
696	for (offset = fdt_next_node(fdt, -1, NULL);
697	     offset >= 0;
698	     offset = fdt_next_node(fdt, offset, NULL)) {
699		if (fdt_get_phandle(fdt, offset) == phandle)
700			return offset;
701	}
702
703	return offset; /* error from fdt_next_node() */
704}
705
706int fdt_stringlist_contains(const char *strlist, int listlen, const char *str)
707{
708	int len = strlen(str);
709	const char *p;
710
711	while (listlen >= len) {
712		if (memcmp(str, strlist, len+1) == 0)
713			return 1;
714		p = memchr(strlist, '\0', listlen);
715		if (!p)
716			return 0; /* malformed strlist.. */
717		listlen -= (p-strlist) + 1;
718		strlist = p + 1;
719	}
720	return 0;
721}
722
723int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property)
724{
725	const char *list, *end;
726	int length, count = 0;
727
728	list = fdt_getprop(fdt, nodeoffset, property, &length);
729	if (!list)
730		return length;
731
732	end = list + length;
733
734	while (list < end) {
735		length = strnlen(list, end - list) + 1;
736
737		/* Abort if the last string isn't properly NUL-terminated. */
738		if (list + length > end)
739			return -FDT_ERR_BADVALUE;
740
741		list += length;
742		count++;
743	}
744
745	return count;
746}
747
748int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property,
749			  const char *string)
750{
751	int length, len, idx = 0;
752	const char *list, *end;
753
754	list = fdt_getprop(fdt, nodeoffset, property, &length);
755	if (!list)
756		return length;
757
758	len = strlen(string) + 1;
759	end = list + length;
760
761	while (list < end) {
762		length = strnlen(list, end - list) + 1;
763
764		/* Abort if the last string isn't properly NUL-terminated. */
765		if (list + length > end)
766			return -FDT_ERR_BADVALUE;
767
768		if (length == len && memcmp(list, string, length) == 0)
769			return idx;
770
771		list += length;
772		idx++;
773	}
774
775	return -FDT_ERR_NOTFOUND;
776}
777
778const char *fdt_stringlist_get(const void *fdt, int nodeoffset,
779			       const char *property, int idx,
780			       int *lenp)
781{
782	const char *list, *end;
783	int length;
784
785	list = fdt_getprop(fdt, nodeoffset, property, &length);
786	if (!list) {
787		if (lenp)
788			*lenp = length;
789
790		return NULL;
791	}
792
793	end = list + length;
794
795	while (list < end) {
796		length = strnlen(list, end - list) + 1;
797
798		/* Abort if the last string isn't properly NUL-terminated. */
799		if (list + length > end) {
800			if (lenp)
801				*lenp = -FDT_ERR_BADVALUE;
802
803			return NULL;
804		}
805
806		if (idx == 0) {
807			if (lenp)
808				*lenp = length - 1;
809
810			return list;
811		}
812
813		list += length;
814		idx--;
815	}
816
817	if (lenp)
818		*lenp = -FDT_ERR_NOTFOUND;
819
820	return NULL;
821}
822
823int fdt_node_check_compatible(const void *fdt, int nodeoffset,
824			      const char *compatible)
825{
826	const void *prop;
827	int len;
828
829	prop = fdt_getprop(fdt, nodeoffset, "compatible", &len);
830	if (!prop)
831		return len;
832
833	return !fdt_stringlist_contains(prop, len, compatible);
834}
835
836int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
837				  const char *compatible)
838{
839	int offset, err;
840
841	FDT_RO_PROBE(fdt);
842
843	/* FIXME: The algorithm here is pretty horrible: we scan each
844	 * property of a node in fdt_node_check_compatible(), then if
845	 * that didn't find what we want, we scan over them again
846	 * making our way to the next node.  Still it's the easiest to
847	 * implement approach; performance can come later. */
848	for (offset = fdt_next_node(fdt, startoffset, NULL);
849	     offset >= 0;
850	     offset = fdt_next_node(fdt, offset, NULL)) {
851		err = fdt_node_check_compatible(fdt, offset, compatible);
852		if ((err < 0) && (err != -FDT_ERR_NOTFOUND))
853			return err;
854		else if (err == 0)
855			return offset;
856	}
857
858	return offset; /* error from fdt_next_node() */
859}