From be6026838e45b67800ac803f4ad8cca3cde57d6d Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 1 Jun 2012 14:12:38 +1000 Subject: [PATCH] libfdt: Add helper function to create a trivial, empty tree The libfdt read/write functions are now usable enough that it's become a moderately common pattern to use them to build and manipulate a device tree from scratch. For example, we do so ourself in our rw_tree1 testcase, and qemu is starting to use this model when building device trees for some targets such as e500. However, the read/write functions require some sort of valid tree to begin with, so this necessitates either having a trivial canned dtb to begin with or, more commonly, creating an empty tree using the serial-write functions first. This patch adds a helper function which uses the serial-write functions to create a trivial, empty but complete and valid tree in a supplied buffer, ready for manipulation with the read/write functions. Signed-off-by: David Gibson --- libfdt/Makefile.libfdt | 2 +- libfdt/fdt_empty_tree.c | 84 +++++++++++++++++++++++++++++++++++++++++ libfdt/libfdt.h | 1 + tests/rw_tree1.c | 12 +----- 4 files changed, 87 insertions(+), 12 deletions(-) create mode 100644 libfdt/fdt_empty_tree.c diff --git a/libfdt/Makefile.libfdt b/libfdt/Makefile.libfdt index d55a6f8..4366627 100644 --- a/libfdt/Makefile.libfdt +++ b/libfdt/Makefile.libfdt @@ -6,5 +6,5 @@ LIBFDT_soname = libfdt.$(SHAREDLIB_EXT).1 LIBFDT_INCLUDES = fdt.h libfdt.h LIBFDT_VERSION = version.lds -LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_rw.c fdt_strerror.c +LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_rw.c fdt_strerror.c fdt_empty_tree.c LIBFDT_OBJS = $(LIBFDT_SRCS:%.c=%.o) diff --git a/libfdt/fdt_empty_tree.c b/libfdt/fdt_empty_tree.c new file mode 100644 index 0000000..f72d13b --- /dev/null +++ b/libfdt/fdt_empty_tree.c @@ -0,0 +1,84 @@ +/* + * libfdt - Flat Device Tree manipulation + * Copyright (C) 2012 David Gibson, IBM Corporation. + * + * libfdt is dual licensed: you can use it either under the terms of + * the GPL, or the BSD license, at your option. + * + * a) This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this library; if not, write to the Free + * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, + * MA 02110-1301 USA + * + * Alternatively, + * + * b) Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * 1. Redistributions of source code must retain the above + * copyright notice, this list of conditions and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND + * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR + * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, + * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#include "libfdt_env.h" + +#include +#include + +#include "libfdt_internal.h" + +int fdt_create_empty_tree(void *buf, int bufsize) +{ + int err; + + err = fdt_create(buf, bufsize); + if (err) + return err; + + err = fdt_finish_reservemap(buf); + if (err) + return err; + + err = fdt_begin_node(buf, ""); + if (err) + return err; + + err = fdt_end_node(buf); + if (err) + return err; + + err = fdt_finish(buf); + if (err) + return err; + + return fdt_open_into(buf, buf, bufsize); +} + diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h index 35d78b8..73f4975 100644 --- a/libfdt/libfdt.h +++ b/libfdt/libfdt.h @@ -1014,6 +1014,7 @@ int fdt_finish(void *fdt); /* Read-write functions */ /**********************************************************************/ +int fdt_create_empty_tree(void *buf, int bufsize); int fdt_open_into(const void *fdt, void *buf, int bufsize); int fdt_pack(void *fdt); diff --git a/tests/rw_tree1.c b/tests/rw_tree1.c index f4965ec..103a24d 100644 --- a/tests/rw_tree1.c +++ b/tests/rw_tree1.c @@ -57,17 +57,7 @@ int main(int argc, char *argv[]) fdt = xmalloc(SPACE); /* First create empty tree with SW */ - CHECK(fdt_create(fdt, SPACE)); - - CHECK(fdt_finish_reservemap(fdt)); - CHECK(fdt_begin_node(fdt, "")); - CHECK(fdt_end_node(fdt)); - CHECK(fdt_finish(fdt)); - - verbose_printf("Built empty tree, totalsize = %d\n", - fdt_totalsize(fdt)); - - CHECK(fdt_open_into(fdt, fdt, SPACE)); + CHECK(fdt_create_empty_tree(fdt, SPACE)); CHECK(fdt_add_mem_rsv(fdt, TEST_ADDR_1, TEST_SIZE_1)); CHECK(fdt_add_mem_rsv(fdt, TEST_ADDR_2, TEST_SIZE_2));