Adding module detect functionality

Scripts/gadget.sh

@@ -2,6 +2,17 @@
 # Adapted from
 # "Using OTG mode on Raspberry Pi SBCs"
 # https://pip-assets.raspberrypi.com/categories/685-app-notes-guides-whitepapers/documents/RP-009276-WP/Using-OTG-mode-on-Raspberry-Pi-SBCs
+
+# Is the dwc2 overlay installed?  Nothing will work if it isn't.
+LOGGER="systemd-cat -t gadget.sh"
+if lsmod | grep -q "dwc2"; then
+    $LOGGER -p info "DWC2 module loaded, setting up OTG gadget serial and ethernet"
+else
+    $LOGGER -p warning "DWC2 module missing.  Aborting OTG setup"
+    exit 1
+fi
+
+
 sudo modprobe libcomposite
 cd /sys/kernel/config/usb_gadget
 # Create our new gadget
@@ -50,4 +61,4 @@ ln -s functions/ecm.usb0 configs/c.1/
 
 ## USB Device Controller update
 UDC=`ls /sys/class/udc`
-echo $UDC > UDC
+echo $UDC > UDC