stm32mp1: platform.mk: migrate to implicit rules

Board Support for the stm32mp1 platform is contained in the device tree,
so if we remove hardcoding of board name from the Makefile, we can build
the intermediary objects once and generate one new tf-a-*.stm32 binary
for every device tree specified. All in one go.

Prepare for this by employing implicit rules.

Change-Id: I5a022a89eb12696cd8cee7bf28ac6be54849901f
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

plat/st/stm32mp1/platform.mk

@@ -151,11 +151,7 @@ endif
 STM32_TF_ELF_LDFLAGS	:=	--hash-style=gnu --as-needed
 STM32_DT_BASENAME	:=	$(DTB_FILE_NAME:.dtb=)
 STM32_TF_STM32		:=	${BUILD_PLAT}/tf-a-${STM32_DT_BASENAME}.stm32
-STM32_TF_BINARY		:=	$(STM32_TF_STM32:.stm32=.bin)
 STM32_TF_LINKERFILE	:=	${BUILD_PLAT}/stm32mp1.ld
-STM32_TF_ELF		:=	$(STM32_TF_STM32:.stm32=.elf)
-STM32_TF_DTBFILE	:=      ${BUILD_PLAT}/fdts/${DTB_FILE_NAME}
-STM32_TF_OBJS		:=	${BUILD_PLAT}/stm32mp1.o
 
 BL2_CFLAGS	+=	-DPLAT_XLAT_TABLES_DYNAMIC=1
 
@@ -191,32 +187,32 @@ check_dtc_version:
 	fi
 
 
-${STM32_TF_OBJS}:	plat/st/stm32mp1/stm32mp1.S bl2 ${BL32_DEP} ${STM32_TF_DTBFILE}
-			@echo "  AS      $<"
+${BUILD_PLAT}/stm32mp1-%.o:	${BUILD_PLAT}/fdts/%.dtb plat/st/stm32mp1/stm32mp1.S bl2 ${BL32_DEP}
+			@echo "  AS      stm32mp1.S"
 			${Q}${AS} ${ASFLAGS} ${TF_CFLAGS} \
 				${BL32_PATH} \
 				-DBL2_BIN_PATH=\"${BUILD_PLAT}/bl2.bin\" \
-				-DDTB_BIN_PATH=\"${STM32_TF_DTBFILE}\" \
+				-DDTB_BIN_PATH=\"$<\" \
 				-c plat/st/stm32mp1/stm32mp1.S -o $@
 
 ${STM32_TF_LINKERFILE}:	plat/st/stm32mp1/stm32mp1.ld.S ${BUILD_PLAT}
 			@echo "  LDS     $<"
 			${Q}${AS} ${ASFLAGS} ${TF_CFLAGS} -P -E $< -o $@
 
-${STM32_TF_ELF}:	${STM32_TF_OBJS} ${STM32_TF_LINKERFILE}
+tf-a-%.elf:		stm32mp1-%.o ${STM32_TF_LINKERFILE}
 			@echo "  LDS     $<"
-			${Q}${LD} -o $@ ${STM32_TF_ELF_LDFLAGS} -Map=$(@:.elf=.map) --script ${STM32_TF_LINKERFILE} ${STM32_TF_OBJS}
+			${Q}${LD} -o $@ ${STM32_TF_ELF_LDFLAGS} -Map=$(@:.elf=.map) --script ${STM32_TF_LINKERFILE} $<
 
-${STM32_TF_BINARY}:	${STM32_TF_ELF}
-			${Q}${OC} -O binary ${STM32_TF_ELF} $@
+tf-a-%.bin:		tf-a-%.elf
+			${Q}${OC} -O binary $< $@
 			@echo
 			@echo "Built $@ successfully"
 			@echo
 
-${STM32_TF_STM32}:	stm32image ${STM32_TF_BINARY}
+tf-a-%.stm32:		tf-a-%.bin stm32image
 			@echo
 			@echo "Generated $@"
 			$(eval LOADADDR =  $(shell cat $(@:.stm32=.map) | grep RAM | awk '{print $$2}'))
 			$(eval ENTRY =  $(shell cat $(@:.stm32=.map) | grep "__BL2_IMAGE_START" | awk '{print $$1}'))
-			${STM32IMAGE} -s ${STM32_TF_BINARY} -d $@ -l $(LOADADDR) -e ${ENTRY} -v ${STM32_TF_VERSION}
+			${STM32IMAGE} -s $< -d $@ -l $(LOADADDR) -e ${ENTRY} -v ${STM32_TF_VERSION}
 			@echo