-all:
- make -C AudioInput clean
- make -C AudioInput all
-
- make -C AudioOutput clean
- make -C AudioOutput all
-
- make -C CDC clean
- make -C CDC all
-
- make -C DualCDC clean
- make -C DualCDC all
-
- make -C GenericHID clean
- make -C GenericHID all
-
- make -C Joystick clean
- make -C Joystick all
-
- make -C Keyboard clean
- make -C Keyboard all
-
- make -C KeyboardMouse clean
- make -C KeyboardMouse all
-
- make -C MassStorage clean
- make -C MassStorage all
-
- make -C MIDI clean
- make -C MIDI all
-
- make -C Mouse clean
- make -C Mouse all
-
- make -C RNDISEthernet clean
- make -C RNDISEthernet all
-
- make -C USBtoSerial clean
- make -C USBtoSerial all
-
-%:
- make -C AudioInput $@
- make -C AudioOutput $@
- make -C CDC $@
- make -C DualCDC $@
- make -C GenericHID $@
- make -C Joystick $@
- make -C Keyboard $@
- make -C KeyboardMouse $@
- make -C MassStorage $@
- make -C MIDI $@
- make -C Mouse $@
- make -C RNDISEthernet $@
- make -C USBtoSerial $@
+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)
+ $(error EMERGENCY ABORT: INFINITE RECURSION DETECTED)
+endif
+
+# If building without a per-project object directory, we can't build in parallel
+ifeq ($(OBJDIR),)
+ .NOTPARALLEL:
+
+ # Ensure projects are pre-cleaned if the target is the default or "all"
+ ifeq ($(MAKECMDGOALS),)
+ MAKECMDGOALS := clean all
+ endif
+ ifneq ($(findstring all, $(MAKECMDGOALS)),)
+ MAKECMDGOALS := clean $(MAKECMDGOALS)
+ endif
+endif
+
+%: $(PROJECT_DIRECTORIES)
+ @echo . > /dev/null
+
+$(PROJECT_DIRECTORIES):
+ @$(MAKE) -C $@ $(MAKECMDGOALS)
+
+.PHONY: $(PROJECT_DIRECTORIES)