Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 859 insertions, 0 deletions

diff --git a/scripts/dtc/libfdt/fdt_ro.c b/scripts/dtc/libfdt/fdt_ro.c
new file mode 100644
index 000000000..91cc6fefe
--- /dev/null
+++ b/scripts/dtc/libfdt/fdt_ro.c
@@ -0,0 +1,859 @@
+// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
+/*
+ * libfdt - Flat Device Tree manipulation
+ * Copyright (C) 2006 David Gibson, IBM Corporation.
+ */
+#include "libfdt_env.h"
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "libfdt_internal.h"
+
+static int fdt_nodename_eq_(const void *fdt, int offset,
+			    const char *s, int len)
+{
+	int olen;
+	const char *p = fdt_get_name(fdt, offset, &olen);
+
+	if (!p || olen < len)
+		/* short match */
+		return 0;
+
+	if (memcmp(p, s, len) != 0)
+		return 0;
+
+	if (p[len] == '\0')
+		return 1;
+	else if (!memchr(s, '@', len) && (p[len] == '@'))
+		return 1;
+	else
+		return 0;
+}
+
+const char *fdt_get_string(const void *fdt, int stroffset, int *lenp)
+{
+	int32_t totalsize;
+	uint32_t absoffset;
+	size_t len;
+	int err;
+	const char *s, *n;
+
+	if (can_assume(VALID_INPUT)) {
+		s = (const char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
+
+		if (lenp)
+			*lenp = strlen(s);
+		return s;
+	}
+	totalsize = fdt_ro_probe_(fdt);
+	err = totalsize;
+	if (totalsize < 0)
+		goto fail;
+
+	err = -FDT_ERR_BADOFFSET;
+	absoffset = stroffset + fdt_off_dt_strings(fdt);
+	if (absoffset >= (unsigned)totalsize)
+		goto fail;
+	len = totalsize - absoffset;
+
+	if (fdt_magic(fdt) == FDT_MAGIC) {
+		if (stroffset < 0)
+			goto fail;
+		if (can_assume(LATEST) || fdt_version(fdt) >= 17) {
+			if ((unsigned)stroffset >= fdt_size_dt_strings(fdt))
+				goto fail;
+			if ((fdt_size_dt_strings(fdt) - stroffset) < len)
+				len = fdt_size_dt_strings(fdt) - stroffset;
+		}
+	} else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
+		unsigned int sw_stroffset = -stroffset;
+
+		if ((stroffset >= 0) ||
+		    (sw_stroffset > fdt_size_dt_strings(fdt)))
+			goto fail;
+		if (sw_stroffset < len)
+			len = sw_stroffset;
+	} else {
+		err = -FDT_ERR_INTERNAL;
+		goto fail;
+	}
+
+	s = (const char *)fdt + absoffset;
+	n = memchr(s, '\0', len);
+	if (!n) {
+		/* missing terminating NULL */
+		err = -FDT_ERR_TRUNCATED;
+		goto fail;
+	}
+
+	if (lenp)
+		*lenp = n - s;
+	return s;
+
+fail:
+	if (lenp)
+		*lenp = err;
+	return NULL;
+}
+
+const char *fdt_string(const void *fdt, int stroffset)
+{
+	return fdt_get_string(fdt, stroffset, NULL);
+}
+
+static int fdt_string_eq_(const void *fdt, int stroffset,
+			  const char *s, int len)
+{
+	int slen;
+	const char *p = fdt_get_string(fdt, stroffset, &slen);
+
+	return p && (slen == len) && (memcmp(p, s, len) == 0);
+}
+
+int fdt_find_max_phandle(const void *fdt, uint32_t *phandle)
+{
+	uint32_t max = 0;
+	int offset = -1;
+
+	while (true) {
+		uint32_t value;
+
+		offset = fdt_next_node(fdt, offset, NULL);
+		if (offset < 0) {
+			if (offset == -FDT_ERR_NOTFOUND)
+				break;
+
+			return offset;
+		}
+
+		value = fdt_get_phandle(fdt, offset);
+
+		if (value > max)
+			max = value;
+	}
+
+	if (phandle)
+		*phandle = max;
+
+	return 0;
+}
+
+int fdt_generate_phandle(const void *fdt, uint32_t *phandle)
+{
+	uint32_t max;
+	int err;
+
+	err = fdt_find_max_phandle(fdt, &max);
+	if (err < 0)
+		return err;
+
+	if (max == FDT_MAX_PHANDLE)
+		return -FDT_ERR_NOPHANDLES;
+
+	if (phandle)
+		*phandle = max + 1;
+
+	return 0;
+}
+
+static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
+{
+	unsigned int offset = n * sizeof(struct fdt_reserve_entry);
+	unsigned int absoffset = fdt_off_mem_rsvmap(fdt) + offset;
+
+	if (!can_assume(VALID_INPUT)) {
+		if (absoffset < fdt_off_mem_rsvmap(fdt))
+			return NULL;
+		if (absoffset > fdt_totalsize(fdt) -
+		    sizeof(struct fdt_reserve_entry))
+			return NULL;
+	}
+	return fdt_mem_rsv_(fdt, n);
+}
+
+int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
+{
+	const struct fdt_reserve_entry *re;
+
+	FDT_RO_PROBE(fdt);
+	re = fdt_mem_rsv(fdt, n);
+	if (!can_assume(VALID_INPUT) && !re)
+		return -FDT_ERR_BADOFFSET;
+
+	*address = fdt64_ld(&re->address);
+	*size = fdt64_ld(&re->size);
+	return 0;
+}
+
+int fdt_num_mem_rsv(const void *fdt)
+{
+	int i;
+	const struct fdt_reserve_entry *re;
+
+	for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
+		if (fdt64_ld(&re->size) == 0)
+			return i;
+	}
+	return -FDT_ERR_TRUNCATED;
+}
+
+static int nextprop_(const void *fdt, int offset)
+{
+	uint32_t tag;
+	int nextoffset;
+
+	do {
+		tag = fdt_next_tag(fdt, offset, &nextoffset);
+
+		switch (tag) {
+		case FDT_END:
+			if (nextoffset >= 0)
+				return -FDT_ERR_BADSTRUCTURE;
+			else
+				return nextoffset;
+
+		case FDT_PROP:
+			return offset;
+		}
+		offset = nextoffset;
+	} while (tag == FDT_NOP);
+
+	return -FDT_ERR_NOTFOUND;
+}
+
+int fdt_subnode_offset_namelen(const void *fdt, int offset,
+			       const char *name, int namelen)
+{
+	int depth;
+
+	FDT_RO_PROBE(fdt);
+
+	for (depth = 0;
+	     (offset >= 0) && (depth >= 0);
+	     offset = fdt_next_node(fdt, offset, &depth))
+		if ((depth == 1)
+		    && fdt_nodename_eq_(fdt, offset, name, namelen))
+			return offset;
+
+	if (depth < 0)
+		return -FDT_ERR_NOTFOUND;
+	return offset; /* error */
+}
+
+int fdt_subnode_offset(const void *fdt, int parentoffset,
+		       const char *name)
+{
+	return fdt_subnode_offset_namelen(fdt, parentoffset, name, strlen(name));
+}
+
+int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
+{
+	const char *end = path + namelen;
+	const char *p = path;
+	int offset = 0;
+
+	FDT_RO_PROBE(fdt);
+
+	/* see if we have an alias */
+	if (*path != '/') {
+		const char *q = memchr(path, '/', end - p);
+
+		if (!q)
+			q = end;
+
+		p = fdt_get_alias_namelen(fdt, p, q - p);
+		if (!p)
+			return -FDT_ERR_BADPATH;
+		offset = fdt_path_offset(fdt, p);
+
+		p = q;
+	}
+
+	while (p < end) {
+		const char *q;
+
+		while (*p == '/') {
+			p++;
+			if (p == end)
+				return offset;
+		}
+		q = memchr(p, '/', end - p);
+		if (! q)
+			q = end;
+
+		offset = fdt_subnode_offset_namelen(fdt, offset, p, q-p);
+		if (offset < 0)
+			return offset;
+
+		p = q;
+	}
+
+	return offset;
+}
+
+int fdt_path_offset(const void *fdt, const char *path)
+{
+	return fdt_path_offset_namelen(fdt, path, strlen(path));
+}
+
+const char *fdt_get_name(const void *fdt, int nodeoffset, int *len)
+{
+	const struct fdt_node_header *nh = fdt_offset_ptr_(fdt, nodeoffset);
+	const char *nameptr;
+	int err;
+
+	if (((err = fdt_ro_probe_(fdt)) < 0)
+	    || ((err = fdt_check_node_offset_(fdt, nodeoffset)) < 0))
+			goto fail;
+
+	nameptr = nh->name;
+
+	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
+		/*
+		 * For old FDT versions, match the naming conventions of V16:
+		 * give only the leaf name (after all /). The actual tree
+		 * contents are loosely checked.
+		 */
+		const char *leaf;
+		leaf = strrchr(nameptr, '/');
+		if (leaf == NULL) {
+			err = -FDT_ERR_BADSTRUCTURE;
+			goto fail;
+		}
+		nameptr = leaf+1;
+	}
+
+	if (len)
+		*len = strlen(nameptr);
+
+	return nameptr;
+
+ fail:
+	if (len)
+		*len = err;
+	return NULL;
+}
+
+int fdt_first_property_offset(const void *fdt, int nodeoffset)
+{
+	int offset;
+
+	if ((offset = fdt_check_node_offset_(fdt, nodeoffset)) < 0)
+		return offset;
+
+	return nextprop_(fdt, offset);
+}
+
+int fdt_next_property_offset(const void *fdt, int offset)
+{
+	if ((offset = fdt_check_prop_offset_(fdt, offset)) < 0)
+		return offset;
+
+	return nextprop_(fdt, offset);
+}
+
+static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
+						              int offset,
+						              int *lenp)
+{
+	int err;
+	const struct fdt_property *prop;
+
+	if (!can_assume(VALID_INPUT) &&
+	    (err = fdt_check_prop_offset_(fdt, offset)) < 0) {
+		if (lenp)
+			*lenp = err;
+		return NULL;
+	}
+
+	prop = fdt_offset_ptr_(fdt, offset);
+
+	if (lenp)
+		*lenp = fdt32_ld(&prop->len);
+
+	return prop;
+}
+
+const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
+						      int offset,
+						      int *lenp)
+{
+	/* Prior to version 16, properties may need realignment
+	 * and this API does not work. fdt_getprop_*() will, however. */
+
+	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
+		if (lenp)
+			*lenp = -FDT_ERR_BADVERSION;
+		return NULL;
+	}
+
+	return fdt_get_property_by_offset_(fdt, offset, lenp);
+}
+
+static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
+						            int offset,
+						            const char *name,
+						            int namelen,
+							    int *lenp,
+							    int *poffset)
+{
+	for (offset = fdt_first_property_offset(fdt, offset);
+	     (offset >= 0);
+	     (offset = fdt_next_property_offset(fdt, offset))) {
+		const struct fdt_property *prop;
+
+		prop = fdt_get_property_by_offset_(fdt, offset, lenp);
+		if (!can_assume(LIBFDT_FLAWLESS) && !prop) {
+			offset = -FDT_ERR_INTERNAL;
+			break;
+		}
+		if (fdt_string_eq_(fdt, fdt32_ld(&prop->nameoff),
+				   name, namelen)) {
+			if (poffset)
+				*poffset = offset;
+			return prop;
+		}
+	}
+
+	if (lenp)
+		*lenp = offset;
+	return NULL;
+}
+
+
+const struct fdt_property *fdt_get_property_namelen(const void *fdt,
+						    int offset,
+						    const char *name,
+						    int namelen, int *lenp)
+{
+	/* Prior to version 16, properties may need realignment
+	 * and this API does not work. fdt_getprop_*() will, however. */
+	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10) {
+		if (lenp)
+			*lenp = -FDT_ERR_BADVERSION;
+		return NULL;
+	}
+
+	return fdt_get_property_namelen_(fdt, offset, name, namelen, lenp,
+					 NULL);
+}
+
+
+const struct fdt_property *fdt_get_property(const void *fdt,
+					    int nodeoffset,
+					    const char *name, int *lenp)
+{
+	return fdt_get_property_namelen(fdt, nodeoffset, name,
+					strlen(name), lenp);
+}
+
+const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
+				const char *name, int namelen, int *lenp)
+{
+	int poffset;
+	const struct fdt_property *prop;
+
+	prop = fdt_get_property_namelen_(fdt, nodeoffset, name, namelen, lenp,
+					 &poffset);
+	if (!prop)
+		return NULL;
+
+	/* Handle realignment */
+	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 &&
+	    (poffset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+		return prop->data + 4;
+	return prop->data;
+}
+
+const void *fdt_getprop_by_offset(const void *fdt, int offset,
+				  const char **namep, int *lenp)
+{
+	const struct fdt_property *prop;
+
+	prop = fdt_get_property_by_offset_(fdt, offset, lenp);
+	if (!prop)
+		return NULL;
+	if (namep) {
+		const char *name;
+		int namelen;
+
+		if (!can_assume(VALID_INPUT)) {
+			name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff),
+					      &namelen);
+			if (!name) {
+				if (lenp)
+					*lenp = namelen;
+				return NULL;
+			}
+			*namep = name;
+		} else {
+			*namep = fdt_string(fdt, fdt32_ld(&prop->nameoff));
+		}
+	}
+
+	/* Handle realignment */
+	if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 &&
+	    (offset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+		return prop->data + 4;
+	return prop->data;
+}
+
+const void *fdt_getprop(const void *fdt, int nodeoffset,
+			const char *name, int *lenp)
+{
+	return fdt_getprop_namelen(fdt, nodeoffset, name, strlen(name), lenp);
+}
+
+uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
+{
+	const fdt32_t *php;
+	int len;
+
+	/* FIXME: This is a bit sub-optimal, since we potentially scan
+	 * over all the properties twice. */
+	php = fdt_getprop(fdt, nodeoffset, "phandle", &len);
+	if (!php || (len != sizeof(*php))) {
+		php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
+		if (!php || (len != sizeof(*php)))
+			return 0;
+	}
+
+	return fdt32_ld(php);
+}
+
+const char *fdt_get_alias_namelen(const void *fdt,
+				  const char *name, int namelen)
+{
+	int aliasoffset;
+
+	aliasoffset = fdt_path_offset(fdt, "/aliases");
+	if (aliasoffset < 0)
+		return NULL;
+
+	return fdt_getprop_namelen(fdt, aliasoffset, name, namelen, NULL);
+}
+
+const char *fdt_get_alias(const void *fdt, const char *name)
+{
+	return fdt_get_alias_namelen(fdt, name, strlen(name));
+}
+
+int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen)
+{
+	int pdepth = 0, p = 0;
+	int offset, depth, namelen;
+	const char *name;
+
+	FDT_RO_PROBE(fdt);
+
+	if (buflen < 2)
+		return -FDT_ERR_NOSPACE;
+
+	for (offset = 0, depth = 0;
+	     (offset >= 0) && (offset <= nodeoffset);
+	     offset = fdt_next_node(fdt, offset, &depth)) {
+		while (pdepth > depth) {
+			do {
+				p--;
+			} while (buf[p-1] != '/');
+			pdepth--;
+		}
+
+		if (pdepth >= depth) {
+			name = fdt_get_name(fdt, offset, &namelen);
+			if (!name)
+				return namelen;
+			if ((p + namelen + 1) <= buflen) {
+				memcpy(buf + p, name, namelen);
+				p += namelen;
+				buf[p++] = '/';
+				pdepth++;
+			}
+		}
+
+		if (offset == nodeoffset) {
+			if (pdepth < (depth + 1))
+				return -FDT_ERR_NOSPACE;
+
+			if (p > 1) /* special case so that root path is "/", not "" */
+				p--;
+			buf[p] = '\0';
+			return 0;
+		}
+	}
+
+	if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
+		return -FDT_ERR_BADOFFSET;
+	else if (offset == -FDT_ERR_BADOFFSET)
+		return -FDT_ERR_BADSTRUCTURE;
+
+	return offset; /* error from fdt_next_node() */
+}
+
+int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
+				 int supernodedepth, int *nodedepth)
+{
+	int offset, depth;
+	int supernodeoffset = -FDT_ERR_INTERNAL;
+
+	FDT_RO_PROBE(fdt);
+
+	if (supernodedepth < 0)
+		return -FDT_ERR_NOTFOUND;
+
+	for (offset = 0, depth = 0;
+	     (offset >= 0) && (offset <= nodeoffset);
+	     offset = fdt_next_node(fdt, offset, &depth)) {
+		if (depth == supernodedepth)
+			supernodeoffset = offset;
+
+		if (offset == nodeoffset) {
+			if (nodedepth)
+				*nodedepth = depth;
+
+			if (supernodedepth > depth)
+				return -FDT_ERR_NOTFOUND;
+			else
+				return supernodeoffset;
+		}
+	}
+
+	if (!can_assume(VALID_INPUT)) {
+		if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
+			return -FDT_ERR_BADOFFSET;
+		else if (offset == -FDT_ERR_BADOFFSET)
+			return -FDT_ERR_BADSTRUCTURE;
+	}
+
+	return offset; /* error from fdt_next_node() */
+}
+
+int fdt_node_depth(const void *fdt, int nodeoffset)
+{
+	int nodedepth;
+	int err;
+
+	err = fdt_supernode_atdepth_offset(fdt, nodeoffset, 0, &nodedepth);
+	if (err)
+		return (can_assume(LIBFDT_FLAWLESS) || err < 0) ? err :
+			-FDT_ERR_INTERNAL;
+	return nodedepth;
+}
+
+int fdt_parent_offset(const void *fdt, int nodeoffset)
+{
+	int nodedepth = fdt_node_depth(fdt, nodeoffset);
+
+	if (nodedepth < 0)
+		return nodedepth;
+	return fdt_supernode_atdepth_offset(fdt, nodeoffset,
+					    nodedepth - 1, NULL);
+}
+
+int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
+				  const char *propname,
+				  const void *propval, int proplen)
+{
+	int offset;
+	const void *val;
+	int len;
+
+	FDT_RO_PROBE(fdt);
+
+	/* FIXME: The algorithm here is pretty horrible: we scan each
+	 * property of a node in fdt_getprop(), then if that didn't
+	 * find what we want, we scan over them again making our way
+	 * to the next node.  Still it's the easiest to implement
+	 * approach; performance can come later. */
+	for (offset = fdt_next_node(fdt, startoffset, NULL);
+	     offset >= 0;
+	     offset = fdt_next_node(fdt, offset, NULL)) {
+		val = fdt_getprop(fdt, offset, propname, &len);
+		if (val && (len == proplen)
+		    && (memcmp(val, propval, len) == 0))
+			return offset;
+	}
+
+	return offset; /* error from fdt_next_node() */
+}
+
+int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
+{
+	int offset;
+
+	if ((phandle == 0) || (phandle == ~0U))
+		return -FDT_ERR_BADPHANDLE;
+
+	FDT_RO_PROBE(fdt);
+
+	/* FIXME: The algorithm here is pretty horrible: we
+	 * potentially scan each property of a node in
+	 * fdt_get_phandle(), then if that didn't find what
+	 * we want, we scan over them again making our way to the next
+	 * node.  Still it's the easiest to implement approach;
+	 * performance can come later. */
+	for (offset = fdt_next_node(fdt, -1, NULL);
+	     offset >= 0;
+	     offset = fdt_next_node(fdt, offset, NULL)) {
+		if (fdt_get_phandle(fdt, offset) == phandle)
+			return offset;
+	}
+
+	return offset; /* error from fdt_next_node() */
+}
+
+int fdt_stringlist_contains(const char *strlist, int listlen, const char *str)
+{
+	int len = strlen(str);
+	const char *p;
+
+	while (listlen >= len) {
+		if (memcmp(str, strlist, len+1) == 0)
+			return 1;
+		p = memchr(strlist, '\0', listlen);
+		if (!p)
+			return 0; /* malformed strlist.. */
+		listlen -= (p-strlist) + 1;
+		strlist = p + 1;
+	}
+	return 0;
+}
+
+int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property)
+{
+	const char *list, *end;
+	int length, count = 0;
+
+	list = fdt_getprop(fdt, nodeoffset, property, &length);
+	if (!list)
+		return length;
+
+	end = list + length;
+
+	while (list < end) {
+		length = strnlen(list, end - list) + 1;
+
+		/* Abort if the last string isn't properly NUL-terminated. */
+		if (list + length > end)
+			return -FDT_ERR_BADVALUE;
+
+		list += length;
+		count++;
+	}
+
+	return count;
+}
+
+int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property,
+			  const char *string)
+{
+	int length, len, idx = 0;
+	const char *list, *end;
+
+	list = fdt_getprop(fdt, nodeoffset, property, &length);
+	if (!list)
+		return length;
+
+	len = strlen(string) + 1;
+	end = list + length;
+
+	while (list < end) {
+		length = strnlen(list, end - list) + 1;
+
+		/* Abort if the last string isn't properly NUL-terminated. */
+		if (list + length > end)
+			return -FDT_ERR_BADVALUE;
+
+		if (length == len && memcmp(list, string, length) == 0)
+			return idx;
+
+		list += length;
+		idx++;
+	}
+
+	return -FDT_ERR_NOTFOUND;
+}
+
+const char *fdt_stringlist_get(const void *fdt, int nodeoffset,
+			       const char *property, int idx,
+			       int *lenp)
+{
+	const char *list, *end;
+	int length;
+
+	list = fdt_getprop(fdt, nodeoffset, property, &length);
+	if (!list) {
+		if (lenp)
+			*lenp = length;
+
+		return NULL;
+	}
+
+	end = list + length;
+
+	while (list < end) {
+		length = strnlen(list, end - list) + 1;
+
+		/* Abort if the last string isn't properly NUL-terminated. */
+		if (list + length > end) {
+			if (lenp)
+				*lenp = -FDT_ERR_BADVALUE;
+
+			return NULL;
+		}
+
+		if (idx == 0) {
+			if (lenp)
+				*lenp = length - 1;
+
+			return list;
+		}
+
+		list += length;
+		idx--;
+	}
+
+	if (lenp)
+		*lenp = -FDT_ERR_NOTFOUND;
+
+	return NULL;
+}
+
+int fdt_node_check_compatible(const void *fdt, int nodeoffset,
+			      const char *compatible)
+{
+	const void *prop;
+	int len;
+
+	prop = fdt_getprop(fdt, nodeoffset, "compatible", &len);
+	if (!prop)
+		return len;
+
+	return !fdt_stringlist_contains(prop, len, compatible);
+}
+
+int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
+				  const char *compatible)
+{
+	int offset, err;
+
+	FDT_RO_PROBE(fdt);
+
+	/* FIXME: The algorithm here is pretty horrible: we scan each
+	 * property of a node in fdt_node_check_compatible(), then if
+	 * that didn't find what we want, we scan over them again
+	 * making our way to the next node.  Still it's the easiest to
+	 * implement approach; performance can come later. */
+	for (offset = fdt_next_node(fdt, startoffset, NULL);
+	     offset >= 0;
+	     offset = fdt_next_node(fdt, offset, NULL)) {
+		err = fdt_node_check_compatible(fdt, offset, compatible);
+		if ((err < 0) && (err != -FDT_ERR_NOTFOUND))
+			return err;
+		else if (err == 0)
+			return offset;
+	}
+
+	return offset; /* error from fdt_next_node() */
+}