diff --git a/Makefile b/Makefile
index 6efed72..df9f73d 100644
--- a/Makefile
+++ b/Makefile
@@ -68,6 +68,9 @@
 # Always enable serprog for now. Needs to be disabled on Windows.
 CONFIG_SERPROG ?= yes
 
+# Bitbanging SPI infrastructure is not used yet.
+CONFIG_BITBANG_SPI ?= no
+
 # Always enable 3Com NICs for now.
 CONFIG_NIC3COM ?= yes
 
@@ -94,6 +97,11 @@
 endif
 endif
 
+ifeq ($(CONFIG_BITBANG_SPI), yes)
+FEATURE_CFLAGS += -D'BITBANG_SPI_SUPPORT=1'
+OBJS += bitbang_spi.o
+endif
+
 ifeq ($(CONFIG_NIC3COM), yes)
 FEATURE_CFLAGS += -D'NIC3COM_SUPPORT=1'
 OBJS += nic3com.o