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 <david@gibson.dropbear.id.au>
From git://git.jdl.com/software/dtc.git patch hash be6026838 with
adaptations to include/libfdt.h and lib/libfdt/Makefile for the U-Boot
environment.
Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile
index c965577..0693d4b 100644
--- a/lib/libfdt/Makefile
+++ b/lib/libfdt/Makefile
@@ -27,7 +27,7 @@
SOBJS =
-COBJS-libfdt += fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o fdt_wip.o
+COBJS-libfdt += fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o fdt_wip.o fdt_empty_tree.o
COBJS-$(CONFIG_OF_LIBFDT) += $(COBJS-libfdt)
COBJS-$(CONFIG_FIT) += $(COBJS-libfdt)