build: consolidate directory creation rules
This commit streamlines directory creation by introducing a single
pattern rule to automatically make directories for which there is a
dependency.
We currently use several macros to generate rules to create directories
upon dependence, which is a significant amount of code and a lot of
redundancy. The rule introduced by this change represents a catch-all:
any rule dependency on a path ending in a forward slash is automatically
created.
Now, rules can rely on an unordered dependency (`|`) on `$$(@D)/` which,
when secondary expansion is enabled, expands to the directory of the
target being built, e.g.:
build/main.o: main.c | $$(@D)/ # automatically creates `build/`
Change-Id: I7e554efa2ac850e779bb302fd9c7fbb239886c9f
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/plat/st/common/common_rules.mk b/plat/st/common/common_rules.mk
index 8b81c7f..fba7783 100644
--- a/plat/st/common/common_rules.mk
+++ b/plat/st/common/common_rules.mk
@@ -41,7 +41,7 @@
fi
# Create DTB file for BL2
-${BUILD_PLAT}/fdts/%-bl2.dts: fdts/%.dts fdts/${BL2_DTSI} | ${BUILD_PLAT} fdt_dirs
+${BUILD_PLAT}/fdts/%-bl2.dts: fdts/%.dts fdts/${BL2_DTSI} | $$(@D)/
$(q)echo '#include "$(patsubst fdts/%,%,$<)"' > $@
$(q)echo '#include "${BL2_DTSI}"' >> $@