Introduce Verifying Program Loader (VPL)

Add support for VPL, a new phase of U-Boot. This runs after TPL. It is
responsible for selecting which SPL binary to run, based on a
verified-boot process.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 82c35a9..ea80f00 100644
--- a/Makefile
+++ b/Makefile
@@ -911,6 +911,12 @@
 TPL_SIZE_CHECK =
 endif
 
+ifneq ($(CONFIG_VPL_SIZE_LIMIT),0x0)
+VPL_SIZE_CHECK = @$(call size_check,$@,$(CONFIG_VPL_SIZE_LIMIT))
+else
+VPL_SIZE_CHECK =
+endif
+
 # Statically apply RELA-style relocations (currently arm64 only)
 # This is useful for arm64 where static relocation needs to be performed on
 # the raw binary, but certain simulators only accept an ELF file (but don't
@@ -951,6 +957,7 @@
 endif
 endif
 INPUTS-$(CONFIG_TPL) += tpl/u-boot-tpl.bin
+INPUTS-$(CONFIG_VPL) += vpl/u-boot-vpl.bin
 
 # Allow omitting the .dtb output if it is not normally used
 INPUTS-$(CONFIG_OF_SEPARATE) += $(if $(CONFIG_OF_OMIT_DTB),dts/dt.dtb,u-boot.dtb)
@@ -2117,6 +2124,13 @@
 tpl/u-boot-tpl: tools prepare $(if $(CONFIG_TPL_OF_CONTROL),dts/dt.dtb)
 	$(Q)$(MAKE) obj=tpl -f $(srctree)/scripts/Makefile.spl all
 
+vpl/u-boot-vpl.bin: vpl/u-boot-vpl
+	@:
+	$(VPL_SIZE_CHECK)
+
+vpl/u-boot-vpl: tools prepare $(if $(CONFIG_TPL_OF_CONTROL),dts/dt.dtb)
+	$(Q)$(MAKE) obj=vpl -f $(srctree)/scripts/Makefile.spl all
+
 TAG_SUBDIRS := $(patsubst %,$(srctree)/%,$(u-boot-dirs) include)
 
 FIND := find