Only include UART related files when (at least) one UART driver is enabled

configure.ac

@@ -118,6 +118,9 @@ fi
 # Handle --with-drivers option
 LIBNFC_ARG_WITH_DRIVERS
 
+# Enable UART if 
+AM_CONDITIONAL(UART_ENABLED, [test x"$uart_required" = x"yes"])
+
 # Documentation (default: no)
 AC_ARG_ENABLE([doc],AS_HELP_STRING([--enable-doc],[Enable documentation generation.]),[enable_doc=$enableval],[enable_doc="no"])
 

libnfc/buses/Makefile.am

@@ -6,12 +6,14 @@ noinst_LTLIBRARIES = libnfcbuses.la
 libnfcbuses_la_SOURCES = 
 libnfcbuses_la_CFLAGS = -I$(top_srcdir)/libnfc
 libnfcbuses_la_LIBADD = 
+EXTRA_DIST =
 
-# UART_ENABLED
-libnfcbuses_la_SOURCES += uart.c uart.h
-libnfcbuses_la_CFLAGS +=
-libnfcbuses_la_LIBADD +=
-EXTRA_DIST = uart_posix.c uart_win32.c
+if UART_ENABLED
+  libnfcbuses_la_SOURCES += uart.c uart.h
+  libnfcbuses_la_CFLAGS +=
+  libnfcbuses_la_LIBADD +=
+endif
+EXTRA_DIST += uart.c uart.h uart_posix.c uart_win32.c
 
 if LIBUSB_ENABLED
   libnfcbuses_la_SOURCES += usbbus.c usbbus.h

m4/libnfc_drivers.m4

@@ -55,6 +55,7 @@ AC_DEFUN([LIBNFC_ARG_WITH_DRIVERS],
                   DRIVERS_CFLAGS="$DRIVERS_CFLAGS -DDRIVER_ACR122_USB_ENABLED"
                   ;;
     acr122s)
+                  uart_required="yes"
                   driver_acr122s_enabled="yes"
                   DRIVERS_CFLAGS="$DRIVERS_CFLAGS -DDRIVER_ACR122S_ENABLED"
                   ;;
@@ -64,10 +65,12 @@ AC_DEFUN([LIBNFC_ARG_WITH_DRIVERS],
                   DRIVERS_CFLAGS="$DRIVERS_CFLAGS -DDRIVER_PN53X_USB_ENABLED"
                   ;;
     arygon)
+                  uart_required="yes"
                   driver_arygon_enabled="yes"
                   DRIVERS_CFLAGS="$DRIVERS_CFLAGS -DDRIVER_ARYGON_ENABLED"
                   ;;
     pn532_uart)
+                  uart_required="yes"
                   driver_pn532_uart_enabled="yes"
                   DRIVERS_CFLAGS="$DRIVERS_CFLAGS -DDRIVER_PN532_UART_ENABLED"
                   ;;