Raspberry Pi zero USB Gadget Mode

README.md

@@ -86,6 +86,7 @@ The _RaspberryMatic_ project is a collaborate effort to provide a lightweight, [
 * Latest Linux kernel (RaspberryPi: [4.19.36](https://github.com/raspberrypi/linux/tree/rpi-4.19.y), Tinkerboard: [4.19.40](https://github.com/armbian/build/tree/master/patch/kernel/rockchip-next)) with hard-float (ARMv7) support
 * Support to boot system using an external USB memory stick or hard disk (RaspberryPi3 only) or from internal eMMC storage (ASUS Tinkerboard S)
 * Supports onboard WiFi of RaspberryPi3, Raspberry Pi Zero W or ASUS Tinkerboard as well as various third-party USB WiFi sticks
+* Supports USB Gadget Mode on the Raspberry Pi Zero (after `touch /usr/local/etc/config/gadgetEnabled`)
 * Supports onboard Bluetooth of RaspberryPi3, Raspberry Pi Zero W or ASUS Tinkerboard as well as various third-party USB Bluetooth sticks
 * Supports [Network UPS Tools](http://networkupstools.org) (NUT) setups including USB connection to uninterruptible power supply (UPS) as well as remote NUT server use (e.g. via Synology NAS Network UPS functionality)
 * Support for the following third-party *Hardware Attached on Top* (HAT) boards:

buildroot-external/board/raspberrypi0/config.txt

@@ -46,6 +46,9 @@ dtparam=pwr_led_trigger=timer,act_led_trigger=mmc0
 # add device tree overlay for RPI-RF-MOD
 dtoverlay=rpi-rf-mod
 
+# enable usb gadget mode for the pi zero
+dtoverlay=dwc2
+
 # make sure gpio12 and gpio24 is set as input and pull_up
 gpio=12,24=ip,pu
 

buildroot-external/board/raspberrypi0/genimage.cfg

@@ -29,6 +29,9 @@ image boot.vfat {
     file overlays/pi3-disable-wifi.dtbo {
       image = "rpi-firmware/overlays/pi3-disable-wifi.dtbo"
     }
+    file overlays/dwc2.dtbo {
+      image = "rpi-firmware/overlays/dwc2.dtbo"
+    }
   }
   size = 256M
 }

buildroot-external/configs/raspmatic_rpi0_defconfig

@@ -167,3 +167,4 @@ BR2_PACKAGE_SSDPD=y
 BR2_PACKAGE_EQ3CONFIGD=y
 BR2_PACKAGE_NEOSERVER=y
 BR2_PACKAGE_JAVA_AZUL=y
+BR2_PACKAGE_DTC=y

buildroot-external/overlay/base/etc/init.d/S01USBGadget

@@ -0,0 +1,32 @@
+#!/bin/sh
+#
+# Enable USB Gadget mode
+#
+
+case "$1" in
+  start)
+    if test -f /usr/local/etc/config/gadgetEnabled; then
+      printf "Starting usb gadget mode: "
+      /sbin/modprobe dwc2
+      /sbin/modprobe g_ether host_addr=00:11:22:33:44:55 dev_addr=00:55:66:77:88:99
+      echo "OK"
+    fi
+    ;;
+  stop)
+    if test -f /usr/local/etc/config/gadgetEnabled; then
+      printf "Stopping usb gadget mode: "
+      /sbin/rmmod g_ether
+      /sbin/rmmod dwc2
+      echo "OK"
+    fi
+    ;;
+  restart|reload)
+    "$0" stop
+    "$0" start
+    ;;
+  *)
+    echo "Usage: $0 {start|stop|restart}"
+    exit 1
+esac
+
+exit $?

buildroot-external/overlay/base/lib/udev/rules.d/76-usb-gadget.rules

@@ -0,0 +1,2 @@
+# Rename usb0 to eth0 to make usb gadget ethernet devices work
+SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*",ATTR{address}=="00:55:66:77:88:99",ATTR{dev_id}=="0x0", ATTR{type}=="1",KERNEL=="usb*", NAME="eth0"