cpu: Add a way to use microcode .h files back to the build

The build was changed to remove usage of microcode .h files when
all of the .h files were converted to binary.  This is still
needed for some builds when microcode binaries aren't in the
blobs tree.

Change-Id: Ia323c90efe8aa0b8799fc5cce6197509e466a105
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: http://review.coreboot.org/12333
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

src/cpu/Kconfig

@@ -67,8 +67,16 @@ config SUPPORT_CPU_UCODE_IN_CBFS
 	bool
 	default n
 
+config USES_MICROCODE_HEADER_FILES
+	def_bool n
+	select SUPPORT_CPU_UCODE_IN_CBFS
+	help
+	  This is selected by a board or chipset to set the default for the
+	  microcode source choice to a list of external microcode headers
+
 choice
 	prompt "Include CPU microcode in CBFS" if ARCH_X86
+	default CPU_MICROCODE_CBFS_EXTERNAL_HEADER if USES_MICROCODE_HEADER_FILES
 	default CPU_MICROCODE_CBFS_GENERATE if SUPPORT_CPU_UCODE_IN_CBFS && USE_BLOBS
 	default CPU_MICROCODE_CBFS_NONE if !SUPPORT_CPU_UCODE_IN_CBFS
 
@@ -84,6 +92,22 @@ config CPU_MICROCODE_CBFS_GENERATE
 
 	  If unsure, select this option.
 
+config CPU_MICROCODE_CBFS_EXTERNAL_HEADER
+	bool "Include external microcode header files"
+	help
+	  Select this option if you want to include external c header files
+	  containing the CPU microcode. This will be included as a separate
+	  file in CBFS.
+
+	  A word of caution: only select this option if you are sure the
+	  microcode that you have is newer than the microcode shipping with
+	  coreboot.
+
+	  The microcode file may be removed from the ROM image at a later
+	  time with cbfstool, if desired.
+
+	  If unsure, select "Generate from tree"
+
 config CPU_MICROCODE_CBFS_NONE
 	bool "Do not include microcode updates"
 	help
@@ -135,3 +159,10 @@ config CPU_MICROCODE_MULTIPLE_FILES
 	help
 	  Select this option to install separate microcode container files into
 	  CBFS instead of using the traditional monolithic microcode file format.
+
+config CPU_MICROCODE_HEADER_FILES
+	string "List of space separated microcode header files with the path"
+	depends on CPU_MICROCODE_CBFS_EXTERNAL_HEADER
+	help
+	  A list of one or more microcode header files with path from the
+	  coreboot directory.  These should be separated by spaces.

src/cpu/Makefile.inc

@@ -21,6 +21,15 @@ ifneq ($(CONFIG_CPU_MICROCODE_MULTIPLE_FILES), y)
 cbfs-files-$(CONFIG_CPU_MICROCODE_CBFS_GENERATE)  += cpu_microcode_blob.bin
 endif
 
+ifeq ($(CONFIG_CPU_MICROCODE_CBFS_EXTERNAL_HEADER),y)
+cbfs-files-y  += cpu_microcode_blob.bin
+cpu_microcode_blob.bin-file = $(objgenerated)/microcode.bin
+
+$(objgenerated)/microcode.bin:
+	echo "   util/scripts/ucode_h_to_bin.sh $(objgenerated)/microcode.bin \"$(CONFIG_CPU_MICROCODE_HEADER_FILES)\""
+	util/scripts/ucode_h_to_bin.sh $(objgenerated)/microcode.bin $(CONFIG_CPU_MICROCODE_HEADER_FILES)
+endif
+
 # We just mash all microcode binaries together into one binary to rule them all.
 # This approach assumes that the microcode binaries are properly padded, and
 # their headers specify the correct size. This works fairly well on isolatied
@@ -33,7 +42,7 @@ $(obj)/cpu_microcode_blob.bin: $$(cpu_microcode_bins)
 	@echo $(cpu_microcode_bins)
 	cat /dev/null $+ > $@
 
-cpu_microcode_blob.bin-file := $(obj)/cpu_microcode_blob.bin
+cpu_microcode_blob.bin-file ?= $(obj)/cpu_microcode_blob.bin
 cpu_microcode_blob.bin-type := microcode
 
 ifneq ($(CONFIG_CPU_MICROCODE_CBFS_LOC),)