git subrepo clone https://github.com/libopencm3/libopencm3

subrepo:
  subdir:   "libopencm3"
  merged:   "f5813a54"
upstream:
  origin:   "https://github.com/libopencm3/libopencm3"
  branch:   "master"
  commit:   "f5813a54"
git-subrepo:
  version:  "0.4.3"
  origin:   "???"
  commit:   "???"

libopencm3/tests/gadget-zero/Makefile

@@ -0,0 +1,15 @@
+# This is just a stub makefile used for travis builds
+# to keep things all compiling. Normally you'd use
+# one of the makefiles directly.
+
+# These hoops are to enable parallel make correctly.
+GZ_ALL := $(wildcard Makefile.*)
+
+all: $(GZ_ALL:=.all)
+clean: $(GZ_ALL:=.clean)
+
+%.all:
+	$(MAKE) -f $* all
+%.clean:
+	$(MAKE) -f $* clean
+