rpi-config: make DWC2 USB modes mutually exclusive

ENABLE_DWC2_HOST was not checked against the other DWC2 modes, so
enabling it with ENABLE_DWC2_PERIPHERAL or ENABLE_DWC2_OTG resulted in
conflicting dr_mode overlays in config.txt. Enabling both PERIPHERAL
and OTG resulted in no overlay at all.

Fail the build when more than one mode is enabled.

Fixes #1590

Signed-off-by: Andrei Gherzan <andrei@gherzan.com>

recipes-bsp/bootfiles/rpi-config_git.bb

@@ -247,20 +247,17 @@ do_deploy() {
         echo "hdmi_drive=1" >> $CONFIG
     fi
 
-    # DWC2 USB peripheral support
-    if ([ "${ENABLE_DWC2_PERIPHERAL}" = "1" ] && [ "${ENABLE_DWC2_OTG}" != "1" ]); then
+    # DWC2 USB support (peripheral, host or OTG - mutually exclusive)
+    if [ "${@sum(d.getVar(v) == '1' for v in ['ENABLE_DWC2_PERIPHERAL', 'ENABLE_DWC2_HOST', 'ENABLE_DWC2_OTG'])}" -gt 1 ]; then
+        bbfatal "Only one of ENABLE_DWC2_PERIPHERAL, ENABLE_DWC2_HOST and ENABLE_DWC2_OTG can be enabled"
+    fi
+    if [ "${ENABLE_DWC2_PERIPHERAL}" = "1" ]; then
         echo "# Enable USB peripheral mode" >> $CONFIG
         echo "dtoverlay=dwc2,dr_mode=peripheral" >> $CONFIG
-    fi
-
-    # DWC2 USB host mode support
-    if [ "${ENABLE_DWC2_HOST}" = "1" ]; then
+    elif [ "${ENABLE_DWC2_HOST}" = "1" ]; then
         echo "# Enable USB host mode" >> $CONFIG
         echo "dtoverlay=dwc2,dr_mode=host" >> $CONFIG
-    fi
-    
-    # DWC2 USB OTG support
-    if ([ "${ENABLE_DWC2_OTG}" = "1" ] && [ "${ENABLE_DWC2_PERIPHERAL}" != "1" ]); then
+    elif [ "${ENABLE_DWC2_OTG}" = "1" ]; then
         echo "# Enable USB OTG mode" >> $CONFIG
         echo "dtoverlay=dwc2,dr_mode=otg" >> $CONFIG
     fi