fdt: Makefile: Build python libfdt library if needed

This is needed by binman and dtoc, so if those are being used, check that
the library is present and complain if not. Make sure that any error
appears on stderr so that buildman notices it.

This means that the fallback library (which uses fdtget) will not be used
anymore and swig will need to be installed to use binman / dtoc.

This affects any board which uses binman (currently sunxi and x86) or dtoc
(anything that uses CONFIG_SPL_OF_PLATDATA, currently some rockchip
boards).

Signed-off-by: Simon Glass <sjg@chromium.org>

Makefile

@@ -1116,7 +1116,7 @@ cmd_ldr = $(LD) $(LDFLAGS_$(@F)) \
 
 u-boot.rom: u-boot-x86-16bit.bin u-boot.bin \
 		$(if $(CONFIG_SPL_X86_16BIT_INIT),spl/u-boot-spl.bin) \
-		$(if $(CONFIG_HAVE_REFCODE),refcode.bin) FORCE
+		$(if $(CONFIG_HAVE_REFCODE),refcode.bin) checkbinman FORCE
 	$(call if_changed,binman)
 
 OBJCOPYFLAGS_u-boot-x86-16bit.bin := -O binary -j .start16 -j .resetvec
@@ -1125,7 +1125,8 @@ u-boot-x86-16bit.bin: u-boot FORCE
 endif
 
 ifneq ($(CONFIG_ARCH_SUNXI),)
-u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.img u-boot.dtb FORCE
+u-boot-sunxi-with-spl.bin: spl/sunxi-spl.bin u-boot.img u-boot.dtb \
+		checkbinman FORCE
 	$(call if_changed,binman)
 endif
 
@@ -1354,6 +1355,18 @@ $(version_h): include/config/uboot.release FORCE
 $(timestamp_h): $(srctree)/Makefile FORCE
 	$(call filechk,timestamp.h)
 
+checkbinman: tools
+	@if ! ( echo 'import libfdt' | ( PYTHONPATH=tools python )); then \
+		echo >&2; \
+		echo >&2 '*** binman needs the Python libfdt library.'; \
+		echo >&2 '*** Either install it on your system, or try:'; \
+		echo >&2 '***'; \
+		echo >&2 '*** sudo apt-get install swig libpython-dev'; \
+		echo >&2 '***'; \
+		echo >&2 '*** to have U-Boot build its own version.'; \
+		false; \
+	fi
+
 # ---------------------------------------------------------------------------
 quiet_cmd_cpp_lds = LDS     $@
 cmd_cpp_lds = $(CPP) -Wp,-MD,$(depfile) $(cpp_flags) $(LDPPFLAGS) \

scripts/Makefile.spl

@@ -257,14 +257,12 @@ PHONY += dts_dir
 dts_dir:
 	$(shell [ -d $(obj)/dts ] || mkdir -p $(obj)/dts)
 
-include/generated/dt-structs.h: $(obj)/$(SPL_BIN).dtb dts_dir dtoc
+include/generated/dt-structs.h: $(obj)/$(SPL_BIN).dtb dts_dir checkdtoc
 	$(call if_changed,dtoch)
 
-$(obj)/dts/dt-platdata.c: $(obj)/$(SPL_BIN).dtb dts_dir dtoc
+$(obj)/dts/dt-platdata.c: $(obj)/$(SPL_BIN).dtb dts_dir checkdtoc
 	$(call if_changed,dtocc)
 
-dtoc: #$(objtree)/tools/_libfdt.so
-
 ifdef CONFIG_SAMSUNG
 ifdef CONFIG_VAR_SIZE_SPL
 VAR_SIZE_PARAM = --vs
@@ -357,6 +355,17 @@ ifneq ($(cmd_files),)
   include $(cmd_files)
 endif
 
+checkdtoc: tools
+	@if ! ( echo 'import libfdt' | ( PYTHONPATH=tools python )); then \
+		echo '*** dtoc needs the Python libfdt library. Either '; \
+		echo '*** install it on your system, or try:'; \
+		echo '***'; \
+		echo '*** sudo apt-get install swig libpython-dev'; \
+		echo '***'; \
+		echo '*** to have U-Boot build its own version.'; \
+		false; \
+	fi
+
 PHONY += FORCE
 FORCE: