scripts/dtc: Update to upstream version v1.7.0-93-g1df7b047fe43

This adds the following commits from upstream:

1df7b047fe43 pylibfdt/Makefile.pylibfdt: use project's flags to compile the extension
61e88fdcec52 libfdt: overlay: Fix phandle overwrite check for new subtrees
49d30894466e meson: fix installation with meson-python
d54aaf93673c pylibfdt: clean up python build directory
ab86f1e9fda8 pylibfdt: add VERSION.txt to Python sdist
7b8a30eceabe pylibfdt: fix Python version
ff4f17eb5865 pylibfdt/Makefile.pylibfdt: fix Python library being rebuild during install
9e313b14e684 pylibfdt/meson.build: fix Python library being rebuilt during install
d598fc3648ec tests/run_tests.sh: fix Meson library path being dropped
b98239da2f18 tests/meson.build: fix python and yaml tests not running
c17d76ab5e84 checks: Check the overall length of "interrupt-map"
ae26223a056e libfdt: overlay: Refactor overlay_fixup_phandle
4dd831affd01 libfdt: tests: Update test case for overlay_bad_fixup
e6d294200837 tests: Remove two_roots and named_root from LIBTREE_TESTS_L and add all dtb filenames generated by dumptrees to TESTS_TREES_L in Makefile.tests
855c934e26ae tests: fix tests broken under Meson
4fd3f4f0a95d github: enforce testing pylibfdt and yaml support
9ca7d62dbf0b meson: split run-tests by type
bb51223083a4 meson: fix dependencies of tests
e81900635c95 meson: fix pylibfdt missing dependency on libfdt
822123856980 pylibfdt: fix get_mem_rsv for newer Python versions
1fad065080e6 libfdt: overlay: ensure that existing phandles are not overwritten
b0aacd0a7735 github: add windows/msys CI build
ae97d9745862 github: Don't accidentally suppress test errors
057a7dbbb777 github: Display meson test logs on failure
92b5d4e91678 pylibfdt: Remove some apparently deprecated options from setup.py
417e3299dbd1 github: Update to newer checkout action
5e6cefa17e2d fix MinGW format attribute
24f60011fd43 libfdt: Simplify adjustment of values for local fixups
da39ee0e68b6 libfdt: rework shared/static libraries
a669223f7a60 Makefile: do not hardcode the `install` program path
3fbfdd08afd2 libfdt: fix duplicate meson target
dcef5f834ea3 tests: use correct pkg-config when cross compiling
0b8026ff254f meson: allow building from shallow clones
95c74d71f090 treesource: Restore string list output when no type markers
2283dd78eff5 libfdt: fdt_path_offset_namelen: Reject empty path
79b9e326a162 libfdt: fdt_get_alias_namelen: Validate aliases
52157f13ef3d pylibfdt: Support boolean properties
d77433727566 dtc: fix missing string in usage_opts_help
ad8bf9f9aa39 libfdt: Fix fdt_appendprop_addrrange documentation
6c5e189fb952 github: add workflow for Meson builds
a3dc9f006a78 libfdt: rename libfdt-X.Y.Z.so to libfdt.so.X.Y.Z
35019949c4c7 workflows: build: remove setuptools_scm hack
cd3e2304f4a9 pylibfdt: use fallback version in tarballs
0f5864567745 move release version into VERSION.txt
38165954c13b libfdt: add missing version symbols
5e98b5979354 editorconfig: use tab indentation for version.lds
d030a893be25 tests: generate dtbs in Meson build directory
8d8372b13706 tests: fix use of deprecated meson methods
761114effaf7 pylibtfdt: fix use of deprecated meson method
bf6377a98d97 meson: set minimum Meson version to 0.56.0
4c68e4b16b22 libfdt: fix library version to match project version
bdc5c8793a13 meson: allow disabling tests
f088e381f29e Makefile: allow to install libfdt without building executables
6df5328a902c Fix use of <ctype.h> functions
ccf1f62d59ad libfdt: Fix a typo in libfdt.h
71a8b8ef0adf libfdt: meson: Fix linking on macOS linker
589d8c7653c7 dtc: Add an option to generate __local_fixups__ and __fixups__
e8364666d5ac CI: Add build matrix with multiple Linux distributions
3b02a94b486f dtc: Correct invalid dts output with mixed phandles and integers
d4888958d64b tests: Add additional tests for device graph checks
ea3b9a1d2c5a checks: Fix crash in graph_child_address if 'reg' cell size != 1
b2b9671583e9 livetree: fix off-by-one in propval_cell_n() bounds check
ab481e483061 Add definition for a GitHub Actions CI job
c88038c9b8ca Drop obsolete/broken CI definitions
0ac8b30ba5a1 yaml: Depend on libyaml >= 0.2.3
f1657b2fb5be tests: Add test cases for bad endpoint node and remote-endpoint prop checks
44bb89cafd3d checks: Fix segmentation fault in check_graph_node
60bcf1cde1a8 improve documentation for fdt_path_offset()
a6f997bc77d4 add fdt_get_symbol() and fdt_get_symbol_namelen() functions
18f5ec12a10e use fdt_path_getprop_namelen() in fdt_get_alias_namelen()
df093279282c add fdt_path_getprop_namelen() helper
129bb4b78bc6 doc: dt-object-internal: Fix a typo
390f481521c3 fdtoverlay: Drop a a repeated article
9f8b382ed45e manual: Fix and improve documentation about -@
2cdf93a6d402 fdtoverlay: Fix usage string to not mention "<type>"
72fc810c3025 build-sys: add -Wwrite-strings
083ab26da83b tests: fix leaks spotted by ASAN
6f8b28f49609 livetree: fix leak spotted by ASAN
fd68bb8c5658 Make name_node() xstrdup its name argument
4718189c4ca8 Delay xstrdup() of node and property names coming from a flat tree
0b842c3c8199 Make build_property() xstrdup its name argument
9cceabea1ee0 checks: correct I2C 10-bit address check
0d56145938fe yamltree.c: fix -Werror=discarded-qualifiers & -Werror=cast-qual
61fa22b05f69 checks: make check.data const
7a1d72a788e0 checks.c: fix check_msg() leak
ee5799938697 checks.c: fix heap-buffer-overflow
44c9b73801c1 tests: fix -Wwrite-strings
5b60f5104fcc srcpos.c: fix -Wwrite-strings
32174a66efa4 meson: Fix cell overflow tests when running from meson
64a907f08b9b meson.build: bump version to 1.7.0
e3cde0613bfd Add -Wsuggest-attribute=format warning, correct warnings thus generated
41821821101a Use #ifdef NO_VALGRIND
71c19f20b3ef Do not redefine _GNU_SOURCE if already set
039a99414e77 Bump version to v1.7.0
9b62ec84bb2d Merge remote-tracking branch 'gitlab/main'
3f29d6d85c24 pylibfdt: add size_hint parameter for get_path
2022bb10879d checks: Update #{size,address}-cells check for 'dma-ranges'

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

3 files changed, 389 insertions, 64 deletions

diff --git a/scripts/dtc/libfdt/fdt_overlay.c b/scripts/dtc/libfdt/fdt_overlay.c
index 5c0c3981b89d..28b667ffc490 100644
--- a/scripts/dtc/libfdt/fdt_overlay.c
+++ b/scripts/dtc/libfdt/fdt_overlay.c
@@ -101,26 +101,22 @@ int fdt_overlay_target_offset(const void *fdt, const void *fdto,
 static int overlay_phandle_add_offset(void *fdt, int node,
 				      const char *name, uint32_t delta)
 {
-	const fdt32_t *val;
-	uint32_t adj_val;
+	fdt32_t *valp, val;
 	int len;
 
-	val = fdt_getprop(fdt, node, name, &len);
-	if (!val)
+	valp = fdt_getprop_w(fdt, node, name, &len);
+	if (!valp)
 		return len;
 
-	if (len != sizeof(*val))
+	if (len != sizeof(val))
 		return -FDT_ERR_BADPHANDLE;
 
-	adj_val = fdt32_to_cpu(*val);
-	if ((adj_val + delta) < adj_val)
-		return -FDT_ERR_NOPHANDLES;
-
-	adj_val += delta;
-	if (adj_val == (uint32_t)-1)
+	val = fdt32_ld(valp);
+	if (val + delta < val || val + delta == (uint32_t)-1)
 		return -FDT_ERR_NOPHANDLES;
 
-	return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
+	fdt32_st(valp, val + delta);
+	return 0;
 }
 
 /**
@@ -213,8 +209,8 @@ static int overlay_update_local_node_references(void *fdto,
 
 	fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
 		const fdt32_t *fixup_val;
-		const char *tree_val;
 		const char *name;
+		char *tree_val;
 		int fixup_len;
 		int tree_len;
 		int i;
@@ -228,7 +224,7 @@ static int overlay_update_local_node_references(void *fdto,
 			return -FDT_ERR_BADOVERLAY;
 		fixup_len /= sizeof(uint32_t);
 
-		tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
+		tree_val = fdt_getprop_w(fdto, tree_node, name, &tree_len);
 		if (!tree_val) {
 			if (tree_len == -FDT_ERR_NOTFOUND)
 				return -FDT_ERR_BADOVERLAY;
@@ -237,33 +233,15 @@ static int overlay_update_local_node_references(void *fdto,
 		}
 
 		for (i = 0; i < fixup_len; i++) {
-			fdt32_t adj_val;
-			uint32_t poffset;
+			fdt32_t *refp;
 
-			poffset = fdt32_to_cpu(fixup_val[i]);
+			refp = (fdt32_t *)(tree_val + fdt32_ld_(fixup_val + i));
 
 			/*
-			 * phandles to fixup can be unaligned.
-			 *
-			 * Use a memcpy for the architectures that do
-			 * not support unaligned accesses.
+			 * phandles to fixup can be unaligned, so use
+			 * fdt32_{ld,st}() to read/write them.
 			 */
-			memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
-
-			adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta);
-
-			ret = fdt_setprop_inplace_namelen_partial(fdto,
-								  tree_node,
-								  name,
-								  strlen(name),
-								  poffset,
-								  &adj_val,
-								  sizeof(adj_val));
-			if (ret == -FDT_ERR_NOSPACE)
-				return -FDT_ERR_BADOVERLAY;
-
-			if (ret)
-				return ret;
+			fdt32_st(refp, fdt32_ld(refp) + delta);
 		}
 	}
 
@@ -337,7 +315,7 @@ static int overlay_update_local_references(void *fdto, uint32_t delta)
  * @name: Name of the property holding the phandle reference in the overlay
  * @name_len: number of name characters to consider
  * @poffset: Offset within the overlay property where the phandle is stored
- * @label: Label of the node referenced by the phandle
+ * @phandle: Phandle referencing the node
  *
  * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
  * a node in the base device tree.
@@ -354,30 +332,14 @@ static int overlay_fixup_one_phandle(void *fdt, void *fdto,
 				     int symbols_off,
 				     const char *path, uint32_t path_len,
 				     const char *name, uint32_t name_len,
-				     int poffset, const char *label)
+				     int poffset, uint32_t phandle)
 {
-	const char *symbol_path;
-	uint32_t phandle;
 	fdt32_t phandle_prop;
-	int symbol_off, fixup_off;
-	int prop_len;
+	int fixup_off;
 
 	if (symbols_off < 0)
 		return symbols_off;
 
-	symbol_path = fdt_getprop(fdt, symbols_off, label,
-				  &prop_len);
-	if (!symbol_path)
-		return prop_len;
-
-	symbol_off = fdt_path_offset(fdt, symbol_path);
-	if (symbol_off < 0)
-		return symbol_off;
-
-	phandle = fdt_get_phandle(fdt, symbol_off);
-	if (!phandle)
-		return -FDT_ERR_NOTFOUND;
-
 	fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
 	if (fixup_off == -FDT_ERR_NOTFOUND)
 		return -FDT_ERR_BADOVERLAY;
@@ -416,6 +378,10 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
 	const char *value;
 	const char *label;
 	int len;
+	const char *symbol_path;
+	int prop_len;
+	int symbol_off;
+	uint32_t phandle;
 
 	value = fdt_getprop_by_offset(fdto, property,
 				      &label, &len);
@@ -426,6 +392,18 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
 		return len;
 	}
 
+	symbol_path = fdt_getprop(fdt, symbols_off, label, &prop_len);
+	if (!symbol_path)
+		return prop_len;
+	
+	symbol_off = fdt_path_offset(fdt, symbol_path);
+	if (symbol_off < 0)
+		return symbol_off;
+	
+	phandle = fdt_get_phandle(fdt, symbol_off);
+	if (!phandle)
+		return -FDT_ERR_NOTFOUND;
+
 	do {
 		const char *path, *name, *fixup_end;
 		const char *fixup_str = value;
@@ -467,7 +445,7 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
 
 		ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
 						path, path_len, name, name_len,
-						poffset, label);
+						poffset, phandle);
 		if (ret)
 			return ret;
 	} while (len > 0);
@@ -521,6 +499,255 @@ static int overlay_fixup_phandles(void *fdt, void *fdto)
 }
 
 /**
+ * overlay_adjust_local_conflicting_phandle: Changes a phandle value
+ * @fdto: Device tree overlay
+ * @node: The node the phandle is set for
+ * @fdt_phandle: The new value for the phandle
+ *
+ * returns:
+ *      0 on success
+ *      Negative error code on failure
+ */
+static int overlay_adjust_local_conflicting_phandle(void *fdto, int node,
+						    uint32_t fdt_phandle)
+{
+	const fdt32_t *php;
+	int len, ret;
+
+	php = fdt_getprop(fdto, node, "phandle", &len);
+	if (php && len == sizeof(*php)) {
+		ret = fdt_setprop_inplace_u32(fdto, node, "phandle", fdt_phandle);
+		if (ret)
+			return ret;
+	}
+
+	php = fdt_getprop(fdto, node, "linux,phandle", &len);
+	if (php && len == sizeof(*php)) {
+		ret = fdt_setprop_inplace_u32(fdto, node, "linux,phandle", fdt_phandle);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * overlay_update_node_conflicting_references - Recursively replace phandle values
+ * @fdto: Device tree overlay blob
+ * @tree_node: Node to recurse into
+ * @fixup_node: Node offset of the matching local fixups node
+ * @fdt_phandle: Value to replace phandles with
+ * @fdto_phandle: Value to be replaced
+ *
+ * Replaces all phandles with value @fdto_phandle by @fdt_phandle.
+ *
+ * returns:
+ *      0 on success
+ *      Negative error code on failure
+ */
+static int overlay_update_node_conflicting_references(void *fdto, int tree_node,
+						      int fixup_node,
+						      uint32_t fdt_phandle,
+						      uint32_t fdto_phandle)
+{
+	int fixup_prop;
+	int fixup_child;
+	int ret;
+
+	fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
+		const fdt32_t *fixup_val;
+		const char *name;
+		char *tree_val;
+		int fixup_len;
+		int tree_len;
+		int i;
+
+		fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
+						  &name, &fixup_len);
+		if (!fixup_val)
+			return fixup_len;
+
+		if (fixup_len % sizeof(uint32_t))
+			return -FDT_ERR_BADOVERLAY;
+		fixup_len /= sizeof(uint32_t);
+
+		tree_val = fdt_getprop_w(fdto, tree_node, name, &tree_len);
+		if (!tree_val) {
+			if (tree_len == -FDT_ERR_NOTFOUND)
+				return -FDT_ERR_BADOVERLAY;
+
+			return tree_len;
+		}
+
+		for (i = 0; i < fixup_len; i++) {
+			fdt32_t *refp;
+			uint32_t valp;
+
+			refp = (fdt32_t *)(tree_val + fdt32_ld_(fixup_val + i));
+			valp = fdt32_ld(refp);
+
+			if (valp == fdto_phandle)
+				fdt32_st(refp, fdt_phandle);
+		}
+	}
+
+	fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
+		const char *fixup_child_name = fdt_get_name(fdto, fixup_child, NULL);
+		int tree_child;
+
+		tree_child = fdt_subnode_offset(fdto, tree_node, fixup_child_name);
+
+		if (tree_child == -FDT_ERR_NOTFOUND)
+			return -FDT_ERR_BADOVERLAY;
+		if (tree_child < 0)
+			return tree_child;
+
+		ret = overlay_update_node_conflicting_references(fdto, tree_child,
+								 fixup_child,
+								 fdt_phandle,
+								 fdto_phandle);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * overlay_update_local_conflicting_references - Recursively replace phandle values
+ * @fdto: Device tree overlay blob
+ * @fdt_phandle: Value to replace phandles with
+ * @fdto_phandle: Value to be replaced
+ *
+ * Replaces all phandles with value @fdto_phandle by @fdt_phandle.
+ *
+ * returns:
+ *      0 on success
+ *      Negative error code on failure
+ */
+static int overlay_update_local_conflicting_references(void *fdto,
+						       uint32_t fdt_phandle,
+						       uint32_t fdto_phandle)
+{
+	int fixups;
+
+	fixups = fdt_path_offset(fdto, "/__local_fixups__");
+	if (fixups == -FDT_ERR_NOTFOUND)
+		return 0;
+	if (fixups < 0)
+		return fixups;
+
+	return overlay_update_node_conflicting_references(fdto, 0, fixups,
+							  fdt_phandle,
+							  fdto_phandle);
+}
+
+/**
+ * overlay_prevent_phandle_overwrite_node - Helper function for overlay_prevent_phandle_overwrite
+ * @fdt: Base Device tree blob
+ * @fdtnode: Node in fdt that is checked for an overwrite
+ * @fdto: Device tree overlay blob
+ * @fdtonode: Node in fdto matching @fdtnode
+ *
+ * returns:
+ *      0 on success
+ *      Negative error code on failure
+ */
+static int overlay_prevent_phandle_overwrite_node(void *fdt, int fdtnode,
+						  void *fdto, int fdtonode)
+{
+	uint32_t fdt_phandle, fdto_phandle;
+	int fdtochild;
+
+	fdt_phandle = fdt_get_phandle(fdt, fdtnode);
+	fdto_phandle = fdt_get_phandle(fdto, fdtonode);
+
+	if (fdt_phandle && fdto_phandle) {
+		int ret;
+
+		ret = overlay_adjust_local_conflicting_phandle(fdto, fdtonode,
+							       fdt_phandle);
+		if (ret)
+			return ret;
+
+		ret = overlay_update_local_conflicting_references(fdto,
+								  fdt_phandle,
+								  fdto_phandle);
+		if (ret)
+			return ret;
+	}
+
+	fdt_for_each_subnode(fdtochild, fdto, fdtonode) {
+		const char *name = fdt_get_name(fdto, fdtochild, NULL);
+		int fdtchild;
+		int ret;
+
+		fdtchild = fdt_subnode_offset(fdt, fdtnode, name);
+		if (fdtchild == -FDT_ERR_NOTFOUND)
+			/*
+			 * no further overwrites possible here as this node is
+			 * new
+			 */
+			continue;
+
+		ret = overlay_prevent_phandle_overwrite_node(fdt, fdtchild,
+							     fdto, fdtochild);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * overlay_prevent_phandle_overwrite - Fixes overlay phandles to not overwrite base phandles
+ * @fdt: Base Device Tree blob
+ * @fdto: Device tree overlay blob
+ *
+ * Checks recursively if applying fdto overwrites phandle values in the base
+ * dtb. When such a phandle is found, the fdto is changed to use the fdt's
+ * phandle value to not break references in the base.
+ *
+ * returns:
+ *      0 on success
+ *      Negative error code on failure
+ */
+static int overlay_prevent_phandle_overwrite(void *fdt, void *fdto)
+{
+	int fragment;
+
+	fdt_for_each_subnode(fragment, fdto, 0) {
+		int overlay;
+		int target;
+		int ret;
+
+		overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
+		if (overlay == -FDT_ERR_NOTFOUND)
+			continue;
+
+		if (overlay < 0)
+			return overlay;
+
+		target = fdt_overlay_target_offset(fdt, fdto, fragment, NULL);
+		if (target == -FDT_ERR_NOTFOUND)
+			/*
+			 * The subtree doesn't exist in the base, so nothing
+			 * will be overwritten.
+			 */
+			continue;
+		else if (target < 0)
+			return target;
+
+		ret = overlay_prevent_phandle_overwrite_node(fdt, target,
+							     fdto, overlay);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
  * overlay_apply_node - Merges a node into the base device tree
  * @fdt: Base Device Tree blob
  * @target: Node offset in the base device tree to apply the fragment to
@@ -824,18 +1051,26 @@ int fdt_overlay_apply(void *fdt, void *fdto)
 	if (ret)
 		goto err;
 
+	/* Increase all phandles in the fdto by delta */
 	ret = overlay_adjust_local_phandles(fdto, delta);
 	if (ret)
 		goto err;
 
+	/* Adapt the phandle values in fdto to the above increase */
 	ret = overlay_update_local_references(fdto, delta);
 	if (ret)
 		goto err;
 
+	/* Update fdto's phandles using symbols from fdt */
 	ret = overlay_fixup_phandles(fdt, fdto);
 	if (ret)
 		goto err;
 
+	/* Don't overwrite phandles in fdt */
+	ret = overlay_prevent_phandle_overwrite(fdt, fdto);
+	if (ret)
+		goto err;
+
 	ret = overlay_merge(fdt, fdto);
 	if (ret)
 		goto err;
diff --git a/scripts/dtc/libfdt/fdt_ro.c b/scripts/dtc/libfdt/fdt_ro.c
index 9f6c551a22c2..b78c4e48f1cb 100644
--- a/scripts/dtc/libfdt/fdt_ro.c
+++ b/scripts/dtc/libfdt/fdt_ro.c
@@ -255,6 +255,9 @@ int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
 
 	FDT_RO_PROBE(fdt);
 
+	if (!can_assume(VALID_INPUT) && namelen <= 0)
+		return -FDT_ERR_BADPATH;
+
 	/* see if we have an alias */
 	if (*path != '/') {
 		const char *q = memchr(path, '/', end - p);
@@ -522,16 +525,31 @@ uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
 	return fdt32_ld_(php);
 }
 
+static const void *fdt_path_getprop_namelen(const void *fdt, const char *path,
+					    const char *propname, int propnamelen,
+					    int *lenp)
+{
+	int offset = fdt_path_offset(fdt, path);
+
+	if (offset < 0)
+		return NULL;
+
+	return fdt_getprop_namelen(fdt, offset, propname, propnamelen, lenp);
+}
+
 const char *fdt_get_alias_namelen(const void *fdt,
 				  const char *name, int namelen)
 {
-	int aliasoffset;
+	int len;
+	const char *alias;
 
-	aliasoffset = fdt_path_offset(fdt, "/aliases");
-	if (aliasoffset < 0)
+	alias = fdt_path_getprop_namelen(fdt, "/aliases", name, namelen, &len);
+
+	if (!can_assume(VALID_DTB) &&
+	    !(alias && len > 0 && alias[len - 1] == '\0' && *alias == '/'))
 		return NULL;
 
-	return fdt_getprop_namelen(fdt, aliasoffset, name, namelen, NULL);
+	return alias;
 }
 
 const char *fdt_get_alias(const void *fdt, const char *name)
@@ -539,6 +557,17 @@ const char *fdt_get_alias(const void *fdt, const char *name)
 	return fdt_get_alias_namelen(fdt, name, strlen(name));
 }
 
+const char *fdt_get_symbol_namelen(const void *fdt,
+				   const char *name, int namelen)
+{
+	return fdt_path_getprop_namelen(fdt, "/__symbols__", name, namelen, NULL);
+}
+
+const char *fdt_get_symbol(const void *fdt, const char *name)
+{
+	return fdt_get_symbol_namelen(fdt, name, strlen(name));
+}
+
 int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen)
 {
 	int pdepth = 0, p = 0;
diff --git a/scripts/dtc/libfdt/libfdt.h b/scripts/dtc/libfdt/libfdt.h
index 77ccff19911e..2d409d8e829b 100644
--- a/scripts/dtc/libfdt/libfdt.h
+++ b/scripts/dtc/libfdt/libfdt.h
@@ -524,10 +524,35 @@ int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen);
  * level matching the given component, differentiated only by unit
  * address).
  *
+ * If the path is not absolute (i.e. does not begin with '/'), the
+ * first component is treated as an alias.  That is, the property by
+ * that name is looked up in the /aliases node, and the value of that
+ * property used in place of that first component.
+ *
+ * For example, for this small fragment
+ *
+ * / {
+ *     aliases {
+ *         i2c2 = &foo; // RHS compiles to "/soc@0/i2c@30a40000/eeprom@52"
+ *     };
+ *     soc@0 {
+ *         foo: i2c@30a40000 {
+ *             bar: eeprom@52 {
+ *             };
+ *         };
+ *     };
+ * };
+ *
+ * these would be equivalent:
+ *
+ *   /soc@0/i2c@30a40000/eeprom@52
+ *   i2c2/eeprom@52
+ *
  * returns:
  *	structure block offset of the node with the requested path (>=0), on
  *		success
- *	-FDT_ERR_BADPATH, given path does not begin with '/' or is invalid
+ *	-FDT_ERR_BADPATH, given path does not begin with '/' and the first
+ *		component is not a valid alias
  *	-FDT_ERR_NOTFOUND, if the requested node does not exist
  *      -FDT_ERR_BADMAGIC,
  *	-FDT_ERR_BADVERSION,
@@ -870,6 +895,42 @@ const char *fdt_get_alias_namelen(const void *fdt,
 const char *fdt_get_alias(const void *fdt, const char *name);
 
 /**
+ * fdt_get_symbol_namelen - get symbol based on substring
+ * @fdt: pointer to the device tree blob
+ * @name: name of the symbol to look up
+ * @namelen: number of characters of name to consider
+ *
+ * Identical to fdt_get_symbol(), but only examine the first @namelen
+ * characters of @name for matching the symbol name.
+ *
+ * Return: a pointer to the expansion of the symbol named @name, if it exists,
+ *	   NULL otherwise
+ */
+#ifndef SWIG /* Not available in Python */
+const char *fdt_get_symbol_namelen(const void *fdt,
+				   const char *name, int namelen);
+#endif
+
+/**
+ * fdt_get_symbol - retrieve the path referenced by a given symbol
+ * @fdt: pointer to the device tree blob
+ * @name: name of the symbol to look up
+ *
+ * fdt_get_symbol() retrieves the value of a given symbol.  That is,
+ * the value of the property named @name in the node
+ * /__symbols__. Such a node exists only for a device tree blob that
+ * has been compiled with the -@ dtc option. Each property corresponds
+ * to a label appearing in the device tree source, with the name of
+ * the property being the label and the value being the full path of
+ * the node it is attached to.
+ *
+ * returns:
+ *	a pointer to the expansion of the symbol named 'name', if it exists
+ *	NULL, if the given symbol or the /__symbols__ node does not exist
+ */
+const char *fdt_get_symbol(const void *fdt, const char *name);
+
+/**
  * fdt_get_path - determine the full path of a node
  * @fdt: pointer to the device tree blob
  * @nodeoffset: offset of the node whose path to find
@@ -1450,7 +1511,7 @@ int fdt_nop_node(void *fdt, int nodeoffset);
  * fdt_create_with_flags() begins the process of creating a new fdt with
  * the sequential write interface.
  *
- * fdt creation process must end with fdt_finished() to produce a valid fdt.
+ * fdt creation process must end with fdt_finish() to produce a valid fdt.
  *
  * returns:
  *	0, on success
@@ -1968,7 +2029,7 @@ static inline int fdt_appendprop_cell(void *fdt, int nodeoffset,
  * address and size) to the value of the named property in the given
  * node, or creates a new property with that value if it does not
  * already exist.
- * If "name" is not specified, a default "reg" is used.
+ *
  * Cell sizes are determined by parent's #address-cells and #size-cells.
  *
  * This function may insert data into the blob, and will therefore