src/mainboard/google/octopus/variants/ampton/Makefile.inc - coreboot - Gitiles

 bootblock-y += gpio.c

 romstage-y += gpio.c

 ramstage-y += gpio.c

 smm-y += gpio.c
	bootblock-y += gpio.c

	romstage-y += gpio.c

	ramstage-y += gpio.c

	smm-y += gpio.c