cert_create: Introduce TBBR CoT makefile

Move all TBBR-specific stuff out of the tool's makefile into a
sub-makefile. This will make it easier to define and select an alternate
chain of trust in the future.

Change-Id: I92e366a1999b74cf51127d1771b64b807cd94b29
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

tools/cert_create/Makefile

 #
-# Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -10,53 +10,36 @@ V		?= 0
 DEBUG		:= 0
 BINARY		:= ${PROJECT}${BIN_EXT}
 OPENSSL_DIR	:= /usr
-USE_TBBR_DEFS   := 1
 
+MAKE_HELPERS_DIRECTORY := ../../make_helpers/
+include ${MAKE_HELPERS_DIRECTORY}build_macros.mk
+include ${MAKE_HELPERS_DIRECTORY}build_env.mk
+
+# Common source files.
 OBJECTS := src/cert.o \
            src/cmd_opt.o \
            src/ext.o \
            src/key.o \
            src/main.o \
-           src/sha.o \
-           src/tbbr/tbb_cert.o \
-           src/tbbr/tbb_ext.o \
-           src/tbbr/tbb_key.o
+           src/sha.o
 
-HOSTCCFLAGS := -Wall -std=c99
-
-MAKE_HELPERS_DIRECTORY := ../../make_helpers/
-include ${MAKE_HELPERS_DIRECTORY}build_macros.mk
-include ${MAKE_HELPERS_DIRECTORY}build_env.mk
+# TBBR chain of trust definitions.
+include src/tbbr/tbbr.mk
 
-ifeq (${USE_TBBR_DEFS},1)
-# In this case, cert_tool is platform-independent
-PLAT_MSG		:=	TBBR Generic
-PLAT_INCLUDE		:=	../../include/tools_share
-else
-PLAT_MSG		:=	${PLAT}
-
-TF_PLATFORM_ROOT		:=	../../plat/
-include ${MAKE_HELPERS_DIRECTORY}plat_helpers.mk
-
-PLAT_INCLUDE		:=	$(wildcard ${PLAT_DIR}include)
-
-ifeq ($(PLAT_INCLUDE),)
-  $(error "Error: Invalid platform '${PLAT}' has no include directory.")
-endif
-endif
+HOSTCCFLAGS := -Wall -std=c99
 
 ifeq (${DEBUG},1)
   HOSTCCFLAGS += -g -O0 -DDEBUG -DLOG_LEVEL=40
 else
   HOSTCCFLAGS += -O2 -DLOG_LEVEL=20
 endif
+
 ifeq (${V},0)
   Q := @
 else
   Q :=
 endif
 
-$(eval $(call add_define,USE_TBBR_DEFS))
 HOSTCCFLAGS += ${DEFINES}
 
 # Make soft links and include from local directory otherwise wrong headers

tools/cert_create/src/tbbr/tbbr.mk

+#
+# Copyright (c) 2020, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+USE_TBBR_DEFS   := 1
+$(eval $(call add_define,USE_TBBR_DEFS))
+
+ifeq (${USE_TBBR_DEFS},1)
+# In this case, cert_tool is platform-independent
+PLAT_MSG		:=	TBBR Generic
+PLAT_INCLUDE		:=	../../include/tools_share
+else
+PLAT_MSG		:=	${PLAT}
+
+TF_PLATFORM_ROOT	:=	../../plat/
+include ${MAKE_HELPERS_DIRECTORY}plat_helpers.mk
+
+PLAT_INCLUDE		:=	$(wildcard ${PLAT_DIR}include)
+
+ifeq ($(PLAT_INCLUDE),)
+  $(error "Error: Invalid platform '${PLAT}' has no include directory.")
+endif
+endif
+
+OBJECTS += src/tbbr/tbb_cert.o \
+           src/tbbr/tbb_ext.o \
+           src/tbbr/tbb_key.o