fdt: Add support for embedded device tree (CONFIG_OF_EMBED)

This new option allows U-Boot to embed a binary device tree into its image
to allow run-time control of peripherals. This device tree is for U-Boot's
own use and is not necessarily the same one as is passed to the kernel.

BUG=chromium-os:11623
TEST=build and boot U-Boot on Seaboard

Change-Id: I024d01079a44395e122a8b53e3901ba9a007dc5a
Reviewed-on: http://gerrit.chromium.org/gerrit/621
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

2 files changed, 99 insertions, 0 deletions

diff --git a/dts/Makefile b/dts/Makefile
new file mode 100644
index 0000000000..986a6b3ee3
--- /dev/null
+++ b/dts/Makefile
@@ -0,0 +1,60 @@
+#
+# Copyright (c) 2011 The Chromium OS Authors.
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program 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 Foundatio; either version 2 of
+# the License, or (at your option) any later version.
+#
+# This program 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 program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA 02111-1307 USA
+#
+
+include $(TOPDIR)/config.mk
+
+LIB	= $(obj)libdts.o
+
+# Use a constant name for this so we can access it from C code.
+# objcopy doesn't seem to allow us to set the symbol name independently of
+# the filename.
+DT_BIN	:= dt.dtb
+
+# TODO: get arch properly for objcopy line.
+dt.o: $(TOPDIR)/board/$(BOARDDIR)/$(DEVICE_TREE).dts
+	$(DTC) -R 4 -p 0x1000 -O dtb -o $(DT_BIN) $<
+	$(OBJCOPY) -B armv5te -I binary -O elf32-littlearm $(DT_BIN) dt.o
+	rm $(DT_BIN)
+
+OBJS	:= dt.o
+
+OBJS	:= $(addprefix $(obj),$(OBJS))
+
+all:	$(obj).depend $(LIB)
+
+$(LIB):	$(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
+
+clean:
+	rm -f $(OBJS) $(LIB)
+	rm -f $(DT_BIN)
+
+distclean:	clean
+
+#########################################################################
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/dts/README b/dts/README
new file mode 100644
index 0000000000..ad939b9e66
--- /dev/null
+++ b/dts/README
@@ -0,0 +1,39 @@
+#
+# Copyright (c) 2011 The Chromium OS Authors.
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program 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 Foundatio; either version 2 of
+# the License, or (at your option) any later version.
+#
+# This program 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 program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA 02111-1307 USA
+#
+
+Emebdded Device Tree Support in U-Boot
+======================================
+
+This directory contains a Makefile for building the device tree blob and
+embedding it in your U-Boot image. This is useful since it allows U-Boot to
+configure itself according to what it finds there. If you have a number of
+similar boards with different peripherals, you can describe the features of
+each board in the device tree file, and have a single generic source base.
+
+Put your device tree file in board/<vendor>/dts/<soc>_<board>.dts. It will be
+picked up and built into the image.
+
+
+To do
+=====
+- Provide a way for U-Boot to find a device tree somewhere in memory on startup,
+similar to how the environment works.