mediatek: filogic: wax220: support factory image

Enable building a factory image which can be flashed through the OEM
firmware's web interface.

The Netgear encrypted image seems to be the same as used in WAX202 or
WAX206, including the encryption keys and IV.

Signed-off-by: Stefan Agner <stefan@agner.ch>

target/linux/mediatek/image/filogic.mk

@@ -206,13 +206,24 @@ define Device/netgear_wax220
   DEVICE_MODEL := WAX220
   DEVICE_DTS := mt7986b-netgear-wax220
   DEVICE_DTS_DIR := ../dts
+  NETGEAR_ENC_MODEL := WAX220
+  NETGEAR_ENC_REGION := US
   DEVICE_PACKAGES := kmod-mt7986-firmware mt7986-wo-firmware
   IMAGES := sysupgrade.bin
+  UBINIZE_OPTS := -E 5
+  BLOCKSIZE := 128k
+  PAGESIZE := 2048
+  KERNEL_SIZE := 6144k
+  IMAGE_SIZE := 32768k
   KERNEL_IN_UBI := 1
   KERNEL := kernel-bin | lzma | \
         fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
   KERNEL_INITRAMFS := kernel-bin | lzma | \
         fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb with-initrd | pad-to 64k
+  KERNEL_INITRAMFS_SUFFIX := -recovery.itb
+  IMAGES += factory.img
+  IMAGE/factory.img := append-kernel | pad-to $$(KERNEL_SIZE) | \
+	append-ubi | check-size | netgear-encrypted-factory
   IMAGE/sysupgrade.bin := sysupgrade-tar | append-metadata
 endef
 TARGET_DEVICES += netgear_wax220