x86: Add support for running Intel reference code

Intel has invented yet another binary blob which firmware is required to
run. This is run after SDRAM is ready. It is linked to load at a particular
address, typically 0, but is a relocatable ELF so can be moved if required.

Add support for this in the build system. The file should be placed in the
board directory, and called refcode.elf.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Makefile

@@ -1052,6 +1052,10 @@ ifneq ($(CONFIG_HAVE_VGA_BIOS),)
 IFDTOOL_FLAGS += -w $(CONFIG_VGA_BIOS_ADDR):$(srctree)/board/$(BOARDDIR)/$(CONFIG_VGA_BIOS_FILE)
 endif
 
+ifneq ($(CONFIG_HAVE_REFCODE),)
+IFDTOOL_FLAGS += -w $(CONFIG_X86_REFCODE_ADDR):refcode.bin
+endif
+
 quiet_cmd_ifdtool = IFDTOOL $@
 cmd_ifdtool  = $(IFDTOOL) -c -r $(CONFIG_ROM_SIZE) u-boot.tmp;
 ifneq ($(CONFIG_HAVE_INTEL_ME),)
@@ -1060,7 +1064,15 @@ endif
 cmd_ifdtool += $(IFDTOOL) $(IFDTOOL_FLAGS) u-boot.tmp;
 cmd_ifdtool += mv u-boot.tmp $@
 
-u-boot.rom: u-boot-x86-16bit.bin u-boot.bin FORCE
+refcode.bin: $(srctree)/board/$(BOARDDIR)/refcode.bin FORCE
+	$(call if_changed,copy)
+
+quiet_cmd_ldr = LD      $@
+cmd_ldr = $(LD) $(LDFLAGS_$(@F)) \
+	       $(filter-out FORCE,$^) -o $@
+
+u-boot.rom: u-boot-x86-16bit.bin u-boot.bin FORCE \
+		$(if $(CONFIG_HAVE_REFCODE),refcode.bin)
 	$(call if_changed,ifdtool)
 
 OBJCOPYFLAGS_u-boot-x86-16bit.bin := -O binary -j .start16 -j .resetvec

arch/x86/Kconfig

@@ -327,6 +327,17 @@ config DCACHE_RAM_MRC_VAR_SIZE
 	  memory reference code and must be set correctly or the board will
 	  not boot.
 
+config HAVE_REFCODE
+        bool "Add a Reference Code binary"
+        help
+          Select this option to add a Reference Code binary to the resulting
+          U-Boot image. This is an Intel binary blob that handles system
+          initialisation, in this case the PCH and System Agent.
+
+          Note: Without this binary (on platforms that need it such as
+          broadwell) U-Boot will be missing some critical setup steps.
+          Various peripherals may fail to work.
+
 config SMP
 	bool "Enable Symmetric Multiprocessing"
 	default n

arch/x86/include/asm/cpu.h

@@ -275,4 +275,16 @@ u32 cpu_get_family_model(void);
  */
 u32 cpu_get_stepping(void);
 
+/**
+ * cpu_run_reference_code() - Run the platform reference code
+ *
+ * Some platforms require a binary blob to be executed once SDRAM is
+ * available. This is used to set up various platform features, such as the
+ * platform controller hub (PCH). This function should be implemented by the
+ * CPU-specific code.
+ *
+ * @return 0 on success, -ve on failure
+ */
+int cpu_run_reference_code(void);
+
 #endif