[1/7] libfdt: migrate fdt_rw.c to a wrapper of scripts/dtc/libfdt/fdt_rw.c

Message ID 1515490492-29434-1-git-send-email-yamada.masahiro@socionext.com
State Superseded
Headers show
Series
  • [1/7] libfdt: migrate fdt_rw.c to a wrapper of scripts/dtc/libfdt/fdt_rw.c
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Commit Message

Masahiro Yamada Jan. 9, 2018, 9:34 a.m.
The only difference between scripts/dtc/libfdt/fdt_rw.c and
lib/libfdt/fdt_rw.c is fdt_remove_unused_strings().

It is only used by fdtgrep, so we do not need to compile it for U-Boot
image.  Move it to tools/libfdt/fdw_rw.c so that lib/libfdt/fdt_rw.c
can be a wrapper of scripts/dtc/libfdt/fdt_rw.c.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 lib/libfdt/Makefile   |   5 +-
 lib/libfdt/fdt_rw.c   | 498 +-------------------------------------------------
 lib/libfdt/libfdt.h   |  17 --
 tools/Makefile        |   6 +-
 tools/fdt_host.h      |  17 ++
 tools/fdtgrep.c       |   2 +-
 tools/libfdt/fdt_rw.c |  35 ++++
 7 files changed, 60 insertions(+), 520 deletions(-)
 create mode 100644 tools/libfdt/fdt_rw.c

Comments

Simon Glass Jan. 16, 2018, 2:50 p.m. | #1
On 9 January 2018 at 01:34, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> The only difference between scripts/dtc/libfdt/fdt_rw.c and
> lib/libfdt/fdt_rw.c is fdt_remove_unused_strings().
>
> It is only used by fdtgrep, so we do not need to compile it for U-Boot
> image.  Move it to tools/libfdt/fdw_rw.c so that lib/libfdt/fdt_rw.c
> can be a wrapper of scripts/dtc/libfdt/fdt_rw.c.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
>  lib/libfdt/Makefile   |   5 +-
>  lib/libfdt/fdt_rw.c   | 498 +-------------------------------------------------
>  lib/libfdt/libfdt.h   |  17 --
>  tools/Makefile        |   6 +-
>  tools/fdt_host.h      |  17 ++
>  tools/fdtgrep.c       |   2 +-
>  tools/libfdt/fdt_rw.c |  35 ++++
>  7 files changed, 60 insertions(+), 520 deletions(-)
>  create mode 100644 tools/libfdt/fdt_rw.c

Reviewed-by: Simon Glass <sjg@chromium.org>

Patch

diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile
index be42e94..4e3e12f 100644
--- a/lib/libfdt/Makefile
+++ b/lib/libfdt/Makefile
@@ -11,6 +11,7 @@  obj-y += \
 	fdt_wip.o \
 	fdt_strerror.o \
 	fdt_sw.o \
+	fdt_rw.o \
 	fdt_empty_tree.o \
 	fdt_addresses.o
 
@@ -18,9 +19,7 @@  obj-$(CONFIG_OF_LIBFDT_OVERLAY) += fdt_overlay.o
 
 # Locally modified for U-Boot.
 # TODO: split out the local modifiction.
-obj-y += \
-	fdt_ro.o \
-	fdt_rw.o
+obj-y += fdt_ro.o
 
 # U-Boot own file
 obj-y += fdt_region.o
diff --git a/lib/libfdt/fdt_rw.c b/lib/libfdt/fdt_rw.c
index 3dc7752..aafded0 100644
--- a/lib/libfdt/fdt_rw.c
+++ b/lib/libfdt/fdt_rw.c
@@ -1,496 +1,2 @@ 
-/*
- * libfdt - Flat Device Tree manipulation
- * Copyright (C) 2006 David Gibson, IBM Corporation.
- * SPDX-License-Identifier:	GPL-2.0+ BSD-2-Clause
- */
-#include <libfdt_env.h>
-
-#ifndef USE_HOSTCC
-#include <fdt.h>
-#include <libfdt.h>
-#else
-#include "fdt_host.h"
-#endif
-
-#include "libfdt_internal.h"
-
-static int _fdt_blocks_misordered(const void *fdt,
-			      int mem_rsv_size, int struct_size)
-{
-	return (fdt_off_mem_rsvmap(fdt) < FDT_ALIGN(sizeof(struct fdt_header), 8))
-		|| (fdt_off_dt_struct(fdt) <
-		    (fdt_off_mem_rsvmap(fdt) + mem_rsv_size))
-		|| (fdt_off_dt_strings(fdt) <
-		    (fdt_off_dt_struct(fdt) + struct_size))
-		|| (fdt_totalsize(fdt) <
-		    (fdt_off_dt_strings(fdt) + fdt_size_dt_strings(fdt)));
-}
-
-static int _fdt_rw_check_header(void *fdt)
-{
-	FDT_CHECK_HEADER(fdt);
-
-	if (fdt_version(fdt) < 17)
-		return -FDT_ERR_BADVERSION;
-	if (_fdt_blocks_misordered(fdt, sizeof(struct fdt_reserve_entry),
-				   fdt_size_dt_struct(fdt)))
-		return -FDT_ERR_BADLAYOUT;
-	if (fdt_version(fdt) > 17)
-		fdt_set_version(fdt, 17);
-
-	return 0;
-}
-
-#define FDT_RW_CHECK_HEADER(fdt) \
-	{ \
-		int __err; \
-		if ((__err = _fdt_rw_check_header(fdt)) != 0) \
-			return __err; \
-	}
-
-static inline int _fdt_data_size(void *fdt)
-{
-	return fdt_off_dt_strings(fdt) + fdt_size_dt_strings(fdt);
-}
-
-static int _fdt_splice(void *fdt, void *splicepoint, int oldlen, int newlen)
-{
-	char *p = splicepoint;
-	char *end = (char *)fdt + _fdt_data_size(fdt);
-
-	if (((p + oldlen) < p) || ((p + oldlen) > end))
-		return -FDT_ERR_BADOFFSET;
-	if ((p < (char *)fdt) || ((end - oldlen + newlen) < (char *)fdt))
-		return -FDT_ERR_BADOFFSET;
-	if ((end - oldlen + newlen) > ((char *)fdt + fdt_totalsize(fdt)))
-		return -FDT_ERR_NOSPACE;
-	memmove(p + newlen, p + oldlen, end - p - oldlen);
-	return 0;
-}
-
-static int _fdt_splice_mem_rsv(void *fdt, struct fdt_reserve_entry *p,
-			       int oldn, int newn)
-{
-	int delta = (newn - oldn) * sizeof(*p);
-	int err;
-	err = _fdt_splice(fdt, p, oldn * sizeof(*p), newn * sizeof(*p));
-	if (err)
-		return err;
-	fdt_set_off_dt_struct(fdt, fdt_off_dt_struct(fdt) + delta);
-	fdt_set_off_dt_strings(fdt, fdt_off_dt_strings(fdt) + delta);
-	return 0;
-}
-
-static int _fdt_splice_struct(void *fdt, void *p,
-			      int oldlen, int newlen)
-{
-	int delta = newlen - oldlen;
-	int err;
-
-	if ((err = _fdt_splice(fdt, p, oldlen, newlen)))
-		return err;
-
-	fdt_set_size_dt_struct(fdt, fdt_size_dt_struct(fdt) + delta);
-	fdt_set_off_dt_strings(fdt, fdt_off_dt_strings(fdt) + delta);
-	return 0;
-}
-
-static int _fdt_splice_string(void *fdt, int newlen)
-{
-	void *p = (char *)fdt
-		+ fdt_off_dt_strings(fdt) + fdt_size_dt_strings(fdt);
-	int err;
-
-	if ((err = _fdt_splice(fdt, p, 0, newlen)))
-		return err;
-
-	fdt_set_size_dt_strings(fdt, fdt_size_dt_strings(fdt) + newlen);
-	return 0;
-}
-
-static int _fdt_find_add_string(void *fdt, const char *s)
-{
-	char *strtab = (char *)fdt + fdt_off_dt_strings(fdt);
-	const char *p;
-	char *new;
-	int len = strlen(s) + 1;
-	int err;
-
-	p = _fdt_find_string(strtab, fdt_size_dt_strings(fdt), s);
-	if (p)
-		/* found it */
-		return (p - strtab);
-
-	new = strtab + fdt_size_dt_strings(fdt);
-	err = _fdt_splice_string(fdt, len);
-	if (err)
-		return err;
-
-	memcpy(new, s, len);
-	return (new - strtab);
-}
-
-int fdt_add_mem_rsv(void *fdt, uint64_t address, uint64_t size)
-{
-	struct fdt_reserve_entry *re;
-	int err;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	re = _fdt_mem_rsv_w(fdt, fdt_num_mem_rsv(fdt));
-	err = _fdt_splice_mem_rsv(fdt, re, 0, 1);
-	if (err)
-		return err;
-
-	re->address = cpu_to_fdt64(address);
-	re->size = cpu_to_fdt64(size);
-	return 0;
-}
-
-int fdt_del_mem_rsv(void *fdt, int n)
-{
-	struct fdt_reserve_entry *re = _fdt_mem_rsv_w(fdt, n);
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	if (n >= fdt_num_mem_rsv(fdt))
-		return -FDT_ERR_NOTFOUND;
-
-	return _fdt_splice_mem_rsv(fdt, re, 1, 0);
-}
-
-static int _fdt_resize_property(void *fdt, int nodeoffset, const char *name,
-				int len, struct fdt_property **prop)
-{
-	int oldlen;
-	int err;
-
-	*prop = fdt_get_property_w(fdt, nodeoffset, name, &oldlen);
-	if (!*prop)
-		return oldlen;
-
-	if ((err = _fdt_splice_struct(fdt, (*prop)->data, FDT_TAGALIGN(oldlen),
-				      FDT_TAGALIGN(len))))
-		return err;
-
-	(*prop)->len = cpu_to_fdt32(len);
-	return 0;
-}
-
-static int _fdt_add_property(void *fdt, int nodeoffset, const char *name,
-			     int len, struct fdt_property **prop)
-{
-	int proplen;
-	int nextoffset;
-	int namestroff;
-	int err;
-
-	if ((nextoffset = _fdt_check_node_offset(fdt, nodeoffset)) < 0)
-		return nextoffset;
-
-	namestroff = _fdt_find_add_string(fdt, name);
-	if (namestroff < 0)
-		return namestroff;
-
-	*prop = _fdt_offset_ptr_w(fdt, nextoffset);
-	proplen = sizeof(**prop) + FDT_TAGALIGN(len);
-
-	err = _fdt_splice_struct(fdt, *prop, 0, proplen);
-	if (err)
-		return err;
-
-	(*prop)->tag = cpu_to_fdt32(FDT_PROP);
-	(*prop)->nameoff = cpu_to_fdt32(namestroff);
-	(*prop)->len = cpu_to_fdt32(len);
-	return 0;
-}
-
-int fdt_set_name(void *fdt, int nodeoffset, const char *name)
-{
-	char *namep;
-	int oldlen, newlen;
-	int err;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	namep = (char *)(uintptr_t)fdt_get_name(fdt, nodeoffset, &oldlen);
-	if (!namep)
-		return oldlen;
-
-	newlen = strlen(name);
-
-	err = _fdt_splice_struct(fdt, namep, FDT_TAGALIGN(oldlen+1),
-				 FDT_TAGALIGN(newlen+1));
-	if (err)
-		return err;
-
-	memcpy(namep, name, newlen+1);
-	return 0;
-}
-
-int fdt_setprop_placeholder(void *fdt, int nodeoffset, const char *name,
-			    int len, void **prop_data)
-{
-	struct fdt_property *prop;
-	int err;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	err = _fdt_resize_property(fdt, nodeoffset, name, len, &prop);
-	if (err == -FDT_ERR_NOTFOUND)
-		err = _fdt_add_property(fdt, nodeoffset, name, len, &prop);
-	if (err)
-		return err;
-
-	*prop_data = prop->data;
-	return 0;
-}
-
-int fdt_setprop(void *fdt, int nodeoffset, const char *name,
-		const void *val, int len)
-{
-	void *prop_data;
-	int err;
-
-	err = fdt_setprop_placeholder(fdt, nodeoffset, name, len, &prop_data);
-	if (err)
-		return err;
-
-	if (len)
-		memcpy(prop_data, val, len);
-	return 0;
-}
-
-int fdt_appendprop(void *fdt, int nodeoffset, const char *name,
-		   const void *val, int len)
-{
-	struct fdt_property *prop;
-	int err, oldlen, newlen;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	prop = fdt_get_property_w(fdt, nodeoffset, name, &oldlen);
-	if (prop) {
-		newlen = len + oldlen;
-		err = _fdt_splice_struct(fdt, prop->data,
-					 FDT_TAGALIGN(oldlen),
-					 FDT_TAGALIGN(newlen));
-		if (err)
-			return err;
-		prop->len = cpu_to_fdt32(newlen);
-		memcpy(prop->data + oldlen, val, len);
-	} else {
-		err = _fdt_add_property(fdt, nodeoffset, name, len, &prop);
-		if (err)
-			return err;
-		memcpy(prop->data, val, len);
-	}
-	return 0;
-}
-
-int fdt_delprop(void *fdt, int nodeoffset, const char *name)
-{
-	struct fdt_property *prop;
-	int len, proplen;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	prop = fdt_get_property_w(fdt, nodeoffset, name, &len);
-	if (!prop)
-		return len;
-
-	proplen = sizeof(*prop) + FDT_TAGALIGN(len);
-	return _fdt_splice_struct(fdt, prop, proplen, 0);
-}
-
-int fdt_add_subnode_namelen(void *fdt, int parentoffset,
-			    const char *name, int namelen)
-{
-	struct fdt_node_header *nh;
-	int offset, nextoffset;
-	int nodelen;
-	int err;
-	uint32_t tag;
-	fdt32_t *endtag;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	offset = fdt_subnode_offset_namelen(fdt, parentoffset, name, namelen);
-	if (offset >= 0)
-		return -FDT_ERR_EXISTS;
-	else if (offset != -FDT_ERR_NOTFOUND)
-		return offset;
-
-	/* Try to place the new node after the parent's properties */
-	fdt_next_tag(fdt, parentoffset, &nextoffset); /* skip the BEGIN_NODE */
-	do {
-		offset = nextoffset;
-		tag = fdt_next_tag(fdt, offset, &nextoffset);
-	} while ((tag == FDT_PROP) || (tag == FDT_NOP));
-
-	nh = _fdt_offset_ptr_w(fdt, offset);
-	nodelen = sizeof(*nh) + FDT_TAGALIGN(namelen+1) + FDT_TAGSIZE;
-
-	err = _fdt_splice_struct(fdt, nh, 0, nodelen);
-	if (err)
-		return err;
-
-	nh->tag = cpu_to_fdt32(FDT_BEGIN_NODE);
-	memset(nh->name, 0, FDT_TAGALIGN(namelen+1));
-	memcpy(nh->name, name, namelen);
-	endtag = (fdt32_t *)((char *)nh + nodelen - FDT_TAGSIZE);
-	*endtag = cpu_to_fdt32(FDT_END_NODE);
-
-	return offset;
-}
-
-int fdt_add_subnode(void *fdt, int parentoffset, const char *name)
-{
-	return fdt_add_subnode_namelen(fdt, parentoffset, name, strlen(name));
-}
-
-int fdt_del_node(void *fdt, int nodeoffset)
-{
-	int endoffset;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	endoffset = _fdt_node_end_offset(fdt, nodeoffset);
-	if (endoffset < 0)
-		return endoffset;
-
-	return _fdt_splice_struct(fdt, _fdt_offset_ptr_w(fdt, nodeoffset),
-				  endoffset - nodeoffset, 0);
-}
-
-static void _fdt_packblocks(const char *old, char *new,
-			    int mem_rsv_size, int struct_size)
-{
-	int mem_rsv_off, struct_off, strings_off;
-
-	mem_rsv_off = FDT_ALIGN(sizeof(struct fdt_header), 8);
-	struct_off = mem_rsv_off + mem_rsv_size;
-	strings_off = struct_off + struct_size;
-
-	memmove(new + mem_rsv_off, old + fdt_off_mem_rsvmap(old), mem_rsv_size);
-	fdt_set_off_mem_rsvmap(new, mem_rsv_off);
-
-	memmove(new + struct_off, old + fdt_off_dt_struct(old), struct_size);
-	fdt_set_off_dt_struct(new, struct_off);
-	fdt_set_size_dt_struct(new, struct_size);
-
-	memmove(new + strings_off, old + fdt_off_dt_strings(old),
-		fdt_size_dt_strings(old));
-	fdt_set_off_dt_strings(new, strings_off);
-	fdt_set_size_dt_strings(new, fdt_size_dt_strings(old));
-}
-
-int fdt_open_into(const void *fdt, void *buf, int bufsize)
-{
-	int err;
-	int mem_rsv_size, struct_size;
-	int newsize;
-	const char *fdtstart = fdt;
-	const char *fdtend = fdtstart + fdt_totalsize(fdt);
-	char *tmp;
-
-	FDT_CHECK_HEADER(fdt);
-
-	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
-		* sizeof(struct fdt_reserve_entry);
-
-	if (fdt_version(fdt) >= 17) {
-		struct_size = fdt_size_dt_struct(fdt);
-	} else {
-		struct_size = 0;
-		while (fdt_next_tag(fdt, struct_size, &struct_size) != FDT_END)
-			;
-		if (struct_size < 0)
-			return struct_size;
-	}
-
-	if (!_fdt_blocks_misordered(fdt, mem_rsv_size, struct_size)) {
-		/* no further work necessary */
-		err = fdt_move(fdt, buf, bufsize);
-		if (err)
-			return err;
-		fdt_set_version(buf, 17);
-		fdt_set_size_dt_struct(buf, struct_size);
-		fdt_set_totalsize(buf, bufsize);
-		return 0;
-	}
-
-	/* Need to reorder */
-	newsize = FDT_ALIGN(sizeof(struct fdt_header), 8) + mem_rsv_size
-		+ struct_size + fdt_size_dt_strings(fdt);
-
-	if (bufsize < newsize)
-		return -FDT_ERR_NOSPACE;
-
-	/* First attempt to build converted tree at beginning of buffer */
-	tmp = buf;
-	/* But if that overlaps with the old tree... */
-	if (((tmp + newsize) > fdtstart) && (tmp < fdtend)) {
-		/* Try right after the old tree instead */
-		tmp = (char *)(uintptr_t)fdtend;
-		if ((tmp + newsize) > ((char *)buf + bufsize))
-			return -FDT_ERR_NOSPACE;
-	}
-
-	_fdt_packblocks(fdt, tmp, mem_rsv_size, struct_size);
-	memmove(buf, tmp, newsize);
-
-	fdt_set_magic(buf, FDT_MAGIC);
-	fdt_set_totalsize(buf, bufsize);
-	fdt_set_version(buf, 17);
-	fdt_set_last_comp_version(buf, 16);
-	fdt_set_boot_cpuid_phys(buf, fdt_boot_cpuid_phys(fdt));
-
-	return 0;
-}
-
-int fdt_pack(void *fdt)
-{
-	int mem_rsv_size;
-
-	FDT_RW_CHECK_HEADER(fdt);
-
-	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
-		* sizeof(struct fdt_reserve_entry);
-	_fdt_packblocks(fdt, fdt, mem_rsv_size, fdt_size_dt_struct(fdt));
-	fdt_set_totalsize(fdt, _fdt_data_size(fdt));
-
-	return 0;
-}
-
-int fdt_remove_unused_strings(const void *old, void *new)
-{
-	const struct fdt_property *old_prop;
-	struct fdt_property *new_prop;
-	int size = fdt_totalsize(old);
-	int next_offset, offset;
-	const char *str;
-	int ret;
-	int tag = FDT_PROP;
-
-	/* Make a copy and remove the strings */
-	memcpy(new, old, size);
-	fdt_set_size_dt_strings(new, 0);
-
-	/* Add every property name back into the new string table */
-	for (offset = 0; tag != FDT_END; offset = next_offset) {
-		tag = fdt_next_tag(old, offset, &next_offset);
-		if (tag != FDT_PROP)
-			continue;
-		old_prop = fdt_get_property_by_offset(old, offset, NULL);
-		new_prop = (struct fdt_property *)(unsigned long)
-			fdt_get_property_by_offset(new, offset, NULL);
-		str = fdt_string(old, fdt32_to_cpu(old_prop->nameoff));
-		ret = _fdt_find_add_string(new, str);
-		if (ret < 0)
-			return ret;
-		new_prop->nameoff = cpu_to_fdt32(ret);
-	}
-
-	return 0;
-}
+#include <linux/libfdt_env.h>
+#include "../../scripts/dtc/libfdt/fdt_rw.c"
diff --git a/lib/libfdt/libfdt.h b/lib/libfdt/libfdt.h
index 6af94cb..4e2c841 100644
--- a/lib/libfdt/libfdt.h
+++ b/lib/libfdt/libfdt.h
@@ -1853,23 +1853,6 @@  int fdt_overlay_apply(void *fdt, void *fdto);
 #ifndef SWIG /* Not available in Python */
 const char *fdt_strerror(int errval);
 
-/**
- * fdt_remove_unused_strings() - Remove any unused strings from an FDT
- *
- * This creates a new device tree in @new with unused strings removed. The
- * called can then use fdt_pack() to minimise the space consumed.
- *
- * @old:	Old device tree blog
- * @new:	Place to put new device tree blob, which must be as large as
- *		@old
- * @return
- *	0, on success
- *	-FDT_ERR_BADOFFSET, corrupt device tree
- *	-FDT_ERR_NOSPACE, out of space, which should not happen unless there
- *		is something very wrong with the device tree input
- */
-int fdt_remove_unused_strings(const void *old, void *new);
-
 struct fdt_region {
 	int offset;
 	int size;
diff --git a/tools/Makefile b/tools/Makefile
index 4d32fe5..3274487 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -61,11 +61,11 @@  FIT_SIG_OBJS-$(CONFIG_FIT_SIGNATURE) := common/image-sig.o
 
 # The following files are synced with upstream DTC.
 # Use synced versions from scripts/dtc/libfdt/.
-LIBFDT_SRCS_SYNCED := fdt.c fdt_wip.c fdt_sw.c fdt_strerror.c fdt_empty_tree.c \
-		      fdt_addresses.c fdt_overlay.c
+LIBFDT_SRCS_SYNCED := fdt.c fdt_wip.c fdt_sw.c fdt_rw.c \
+		fdt_strerror.c fdt_empty_tree.c fdt_addresses.c fdt_overlay.c
 # The following files are locally modified for U-Boot (unfotunately).
 # Use U-Boot own versions from lib/libfdt/.
-LIBFDT_SRCS_UNSYNCED := fdt_ro.c fdt_rw.c fdt_region.c
+LIBFDT_SRCS_UNSYNCED := fdt_ro.c fdt_region.c
 
 LIBFDT_OBJS := $(addprefix libfdt/, $(patsubst %.c, %.o, $(LIBFDT_SRCS_SYNCED))) \
 	       $(addprefix lib/libfdt/, $(patsubst %.c, %.o, $(LIBFDT_SRCS_UNSYNCED)))
diff --git a/tools/fdt_host.h b/tools/fdt_host.h
index 134d965..8d4aa06 100644
--- a/tools/fdt_host.h
+++ b/tools/fdt_host.h
@@ -11,6 +11,23 @@ 
 #include "../include/libfdt.h"
 #include "../include/fdt_support.h"
 
+/**
+ * fdt_remove_unused_strings() - Remove any unused strings from an FDT
+ *
+ * This creates a new device tree in @new with unused strings removed. The
+ * called can then use fdt_pack() to minimise the space consumed.
+ *
+ * @old:	Old device tree blog
+ * @new:	Place to put new device tree blob, which must be as large as
+ *		@old
+ * @return
+ *	0, on success
+ *	-FDT_ERR_BADOFFSET, corrupt device tree
+ *	-FDT_ERR_NOSPACE, out of space, which should not happen unless there
+ *		is something very wrong with the device tree input
+ */
+int fdt_remove_unused_strings(const void *old, void *new);
+
 int fit_check_sign(const void *working_fdt, const void *key);
 
 #endif /* __FDT_HOST_H__ */
diff --git a/tools/fdtgrep.c b/tools/fdtgrep.c
index 5897b6d..7af77b7 100644
--- a/tools/fdtgrep.c
+++ b/tools/fdtgrep.c
@@ -16,7 +16,7 @@ 
 #include <string.h>
 #include <unistd.h>
 
-#include "../include/libfdt.h"
+#include "fdt_host.h"
 #include "libfdt_internal.h"
 
 /* Define DEBUG to get some debugging output on stderr */
diff --git a/tools/libfdt/fdt_rw.c b/tools/libfdt/fdt_rw.c
new file mode 100644
index 0000000..e475084
--- /dev/null
+++ b/tools/libfdt/fdt_rw.c
@@ -0,0 +1,35 @@ 
+/* SPDX-License-Identifier:	GPL-2.0+ BSD-2-Clause */
+#include "fdt_host.h"
+#include "../../scripts/dtc/libfdt/fdt_rw.c"
+
+int fdt_remove_unused_strings(const void *old, void *new)
+{
+	const struct fdt_property *old_prop;
+	struct fdt_property *new_prop;
+	int size = fdt_totalsize(old);
+	int next_offset, offset;
+	const char *str;
+	int ret;
+	int tag = FDT_PROP;
+
+	/* Make a copy and remove the strings */
+	memcpy(new, old, size);
+	fdt_set_size_dt_strings(new, 0);
+
+	/* Add every property name back into the new string table */
+	for (offset = 0; tag != FDT_END; offset = next_offset) {
+		tag = fdt_next_tag(old, offset, &next_offset);
+		if (tag != FDT_PROP)
+			continue;
+		old_prop = fdt_get_property_by_offset(old, offset, NULL);
+		new_prop = (struct fdt_property *)(unsigned long)
+			fdt_get_property_by_offset(new, offset, NULL);
+		str = fdt_string(old, fdt32_to_cpu(old_prop->nameoff));
+		ret = _fdt_find_add_string(new, str);
+		if (ret < 0)
+			return ret;
+		new_prop->nameoff = cpu_to_fdt32(ret);
+	}
+
+	return 0;
+}