x86: Build a .rom file which can be flashed to an x86 machine

On x86 machines U-Boot needs to be added to a large ROM image which is
then flashed onto the target board. The ROM has a particular format so it
makes sense for U-Boot to build this image automatically. Unfortunately
it relies on binary blobs so we cannot require this for the default
build as yet.

Create a u-boot.rom output file for this purpose.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index ddea534..23590d9 100644
--- a/Makefile
+++ b/Makefile
@@ -749,6 +749,9 @@
 endif
 ALL-$(CONFIG_REMAKE_ELF) += u-boot.elf
 
+# We can't do this yet due to the need for binary blobs
+# ALL-$(CONFIG_X86_RESET_VECTOR) += u-boot.rom
+
 # enable combined SPL/u-boot/dtb rules for tegra
 ifneq ($(CONFIG_TEGRA),)
 ifeq ($(CONFIG_SPL),y)
@@ -817,7 +820,8 @@
 u-boot.hex u-boot.srec: u-boot FORCE
 	$(call if_changed,objcopy)
 
-OBJCOPYFLAGS_u-boot.bin := -O binary
+OBJCOPYFLAGS_u-boot.bin := -O binary \
+		$(if $(CONFIG_X86_RESET_VECTOR),-R .start16 -R .resetvec)
 
 binary_size_check: u-boot.bin FORCE
 	@file_size=$(shell wc -c u-boot.bin | awk '{print $$1}') ; \
@@ -956,6 +960,36 @@
 	$(call if_changed,mkimage)
 	@dd if=/dev/zero bs=8 count=1 2>/dev/null >> $@
 
+# x86 uses a large ROM. We fill it with 0xff, put the 16-bit stuff (including
+# reset vector) at the top, Intel ME descriptor at the bottom, and U-Boot in
+# the middle.
+ifneq ($(CONFIG_X86_RESET_VECTOR),)
+rom: u-boot.rom FORCE
+
+u-boot.rom: u-boot-x86-16bit.bin u-boot-dtb.bin \
+		$(srctree)/board/$(BOARDDIR)/mrc.bin
+	$(objtree)/tools/ifdtool -c -r $(CONFIG_ROM_SIZE) u-boot.tmp
+	if [ -n "$(CONFIG_HAVE_INTEL_ME)" ]; then \
+		$(objtree)/tools/ifdtool -D \
+			$(srctree)/board/$(BOARDDIR)/descriptor.bin u-boot.tmp; \
+		$(objtree)/tools/ifdtool \
+			-i ME:$(srctree)/board/$(BOARDDIR)/me.bin u-boot.tmp; \
+	fi
+	$(objtree)/tools/ifdtool -w \
+		$(CONFIG_SYS_TEXT_BASE):$(objtree)/u-boot-dtb.bin u-boot.tmp
+	$(objtree)/tools/ifdtool -w \
+		$(CONFIG_X86_MRC_START):$(srctree)/board/$(BOARDDIR)/mrc.bin \
+		u-boot.tmp
+	$(objtree)/tools/ifdtool -w \
+		$(CONFIG_SYS_X86_START16):$(objtree)/u-boot-x86-16bit.bin \
+		u-boot.tmp
+	mv u-boot.tmp $@
+
+OBJCOPYFLAGS_u-boot-x86-16bit.bin := -O binary -j .start16 -j .resetvec
+u-boot-x86-16bit.bin: u-boot FORCE
+	$(call if_changed,objcopy)
+endif
+
 ifneq ($(CONFIG_SUNXI),)
 OBJCOPYFLAGS_u-boot-sunxi-with-spl.bin = -I binary -O binary \
 				   --pad-to=$(CONFIG_SPL_PAD_TO) --gap-fill=0xff