Support for RPI-RF-MOD/HM-MOD-RPI-PCB for HomeMatic/homematicIP communication (#1266)

* add eq3_char_loop package (eQ-3 char loopback kernel module)

* add generic_raw_uart package (low-latency raw UART kernel driver)

* add rpi-rf-mod package 

* add device tree overlay support for RPI-RF-MOD/HM-MOD-RPI-PCB on Raspberry Pi

* enable GPIOLIB and GPIO_SYSFS required for RPI-RF-MOD/HM-MOD-RPI-PCB support.

* add basic RPI-RF-MOD/HM-MOD-RPI-PCB support for ASUS Tinker Board

* add device tree overlay support for ASUS Tinker Board and add
haos-config.txt loading support to U-Boot boot script

buildroot-external/board/asus/hassos-hook.sh

@@ -10,6 +10,10 @@ function hassos_pre_image() {
         "${BINARIES_DIR}/rk3288-tinker.dtb" \
         "${BINARIES_DIR}/rk3288-tinker-s.dtb"
 
+    mkdir -p "${BOOT_DATA}/overlays"
+    cp "${BINARIES_DIR}"/*.dtbo "${BOOT_DATA}/overlays/"
+    cp "${BOARD_DIR}/boot-env.txt" "${BOOT_DATA}/haos-config.txt"
+
     echo "console=tty1" > "${BOOT_DATA}/cmdline.txt"
 
     # SPL

buildroot-external/board/asus/tinker/boot-env.txt

@@ -0,0 +1,2 @@
+# Uncomment this to enable GPIO support for RPI-RF-MOD/HM-MOD-RPI-PCB
+#overlays=rpi-rf-mod

buildroot-external/board/asus/tinker/uboot-boot.ush

@@ -23,14 +23,37 @@ setenv bootargs_hassos "zram.enabled=1 zram.num_devices=3 apparmor=1 security=ap
 setenv bootargs_a "root=PARTUUID=8d3d53e3-6d49-4c38-8349-aff6859e82fd rootfstype=squashfs ro rootwait"
 setenv bootargs_b "root=PARTUUID=a3ec664e-32ce-4665-95ea-7ae90ce9aa20 rootfstype=squashfs ro rootwait"
 
+# Load environment from haos-config.txt
+if test -e mmc ${devnum}:1 haos-config.txt; then
+  fatload mmc ${devnum}:1 ${ramdisk_addr_r} haos-config.txt
+  env import -t ${ramdisk_addr_r} ${filesize}
+fi
+
 # Load extraargs
 fileenv mmc ${devnum}:1 ${ramdisk_addr_r} cmdline.txt cmdline
 
 # Load device tree
 if test "$devnum" = "0"; then
-  fatload mmc ${devnum}:1 ${fdt_addr_r} rk3288-tinker-s.dtb
+  setenv fdtfile "rk3288-tinker-s.dtb"
 else
-  fatload mmc ${devnum}:1 ${fdt_addr_r} rk3288-tinker.dtb
+  setenv fdtfile "rk3288-tinker.dtb"
+fi
+
+echo "Loading standard device tree ${fdtfile}"
+fatload mmc ${devnum}:1 ${fdt_addr_r} ${fdtfile}
+fdt addr ${fdt_addr_r}
+
+# load dt overlays
+fdt resize 65536
+for overlay_file in ${overlays}; do
+  if fatload mmc ${devnum}:1 ${ramdisk_addr_r} overlays/${overlay_file}.dtbo; then
+    echo "Applying kernel provided DT overlay ${overlay_file}.dtbo"
+    fdt apply ${ramdisk_addr_r} || setenv overlay_error "true"
+  fi
+done
+if test "${overlay_error}" = "true"; then
+  echo "Error applying DT overlays, restoring original DT"
+  fatload mmc ${devnum}:1 ${fdt_addr_r} ${fdtfile}
 fi
 
 setenv bootargs

buildroot-external/board/asus/tinker/uboot.config

@@ -1,2 +1,3 @@
 # CONFIG_USB_STORAGE is not set
 # CONFIG_DOS_PARTITION is not set
+CONFIG_OF_LIBFDT_OVERLAY=y

buildroot-external/board/raspberrypi/boot-env.txt

@@ -60,6 +60,12 @@ kernel=u-boot.bin
 # Uncomment this to enable the lirc-rpi module
 #dtoverlay=lirc-rpi
 
+# Uncomment this to enable GPIO support for RPI-RF-MOD/HM-MOD-RPI-PCB
+#enable_uart=1
+#dtparam=i2c_arm=on
+#dtoverlay=miniuart-bt
+#dtoverlay=rpi-rf-mod
+
 # Additional overlays and parameters are documented /boot/overlays/README
 
 # Enable audio (loads snd_bcm2835)

buildroot-external/board/raspberrypi/hassos-hook.sh

@@ -10,6 +10,7 @@ function hassos_pre_image() {
     cp "${BINARIES_DIR}"/*.dtb "${BOOT_DATA}/"
     cp -r "${BINARIES_DIR}/rpi-firmware/"* "${BOOT_DATA}/"
     cp "${BOARD_DIR}/../boot-env.txt" "${BOOT_DATA}/config.txt"
+    cp "${BINARIES_DIR}"/*.dtbo "${BOOT_DATA}/overlays/"
 
     # EEPROM update for Raspberry Pi 4/Compute Module 4
     if grep -Eq "^BR2_PACKAGE_RPI_EEPROM=y$" "${BR2_CONFIG}"; then