-all:
- make -C AVRISP clean
- make -C AVRISP all
-
- make -C Benito clean
- make -C Benito all
-
- make -C Magstripe clean
- make -C Magstripe all
-
- make -C MissileLauncher clean
- make -C MissileLauncher all
-
- make -C USBtoSerial clean
- make -C USBtoSerial all
-
- make -C XPLAINBridge clean
- make -C XPLAINBridge all
+PROJECT_DIRECTORIES := $(shell ls -d */)
+
+# This makefile is potentially infinitely recursive if something really bad
+# happens when determining the set of project directories - hard-abort if
+# more than 10 levels deep to avoid angry emails.
+ifeq ($(MAKELEVEL), 10)
+ $(error EMERGENCY ABORT: INFINITE RECURSION DETECTED)
+endif
+
+# Need to special-case building without a per-project object directory
+ifeq ($(OBJDIR),)
+ # If no target specified, force "clean all" and disallow parallel build
+ ifeq ($(MAKECMDGOALS),)
+ MAKECMDGOALS := clean all
+ .NOTPARALLEL:
+ endif
+
+ # If one of the targets is to build, force "clean" beforehand and disallow parallel build
+ ifneq ($(findstring all, $(MAKECMDGOALS)),)
+ MAKECMDGOALS := clean $(MAKECMDGOALS)
+ .NOTPARALLEL:
+ endif
+endif
+
+%: $(PROJECT_DIRECTORIES)
+ @echo . > /dev/null
+
+$(PROJECT_DIRECTORIES):
+ @$(MAKE) -C $@ $(MAKECMDGOALS)
+
+.PHONY: $(PROJECT_DIRECTORIES)