ramips: add support for ZIO FREEZIO

ZIO FREEZIO is a 2.4/5GHz band AC1200 router, based on MediaTek MT7621A.

Specifications:
- SoC: MT7621AT
- RAM: DDR3 128MB
- Flash: SPI NOR 16MB
- WiFi:
  - 2.4GHz: MT7603EN
  - 5GHz: MT7612EN
- Ethernet: 5x 10/100/1000Mbps
  - Switch: SoC internal
- USB: 1x 3.0
- UART:
  - J4: 3.3V, RX, TX, GND (3.3V is the square pad) / 57600 8N1

Notes:
- FREEZIO has almost the same board as WeVO W2914NS v2.
- Stock firmware is based on OpenWrt BB.

MAC addresses in factory partition:
0x0004: WiFi 2.4GHz (label_mac-8)
0x002e: WAN (label_mac)
0x8004: WiFi 5GHz (label_mac-4)
0xe000: LAN (label_mac+1)

Installation via web interface:
1.  Access web admin page and turn on "OpenWrt UI mode".
2.  Flash sysupgrade image through LuCI, with the "Keep settings" option
    OFF.

Revert to stock firmware:
1.  Perform sysupgrade with stock image.
    Make sure to NOT preserve settings.

Signed-off-by: Sungbo Eo <mans0n@gorani.run>
[rebase, use mt7621_wevo_w2914ns-v2.dtsi]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/dts/mt7621_zio_freezio.dts

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/dts-v1/;
+
+#include "mt7621_wevo_w2914ns-v2.dtsi"
+
+/ {
+	compatible = "zio,freezio", "mediatek,mt7621-soc";
+	model = "ZIO FREEZIO";
+
+	leds {
+		compatible = "gpio-leds";
+
+		usb {
+			label = "freezio:green:usb";
+			gpios = <&gpio0 27 GPIO_ACTIVE_LOW>;
+			trigger-sources = <&xhci_ehci_port1>;
+			linux,default-trigger = "usbport";
+		};
+	};
+};

target/linux/ramips/image/mt7621.mk

@@ -910,3 +910,12 @@ define Device/zbtlink_zbt-wg3526-32m
   SUPPORTED_DEVICES += ac1200pro zbt-wg3526-32M
 endef
 TARGET_DEVICES += zbtlink_zbt-wg3526-32m
+
+define Device/zio_freezio
+  MTK_SOC := mt7621
+  IMAGE_SIZE := 16064k
+  DEVICE_VENDOR := ZIO
+  DEVICE_MODEL := FREEZIO
+  DEVICE_PACKAGES := kmod-mt7603 kmod-mt76x2 kmod-usb3 kmod-usb-ledtrig-usbport wpad-basic
+endef
+TARGET_DEVICES += zio_freezio

target/linux/ramips/mt7621/base-files/etc/board.d/02_network

@@ -45,7 +45,8 @@ ramips_setup_interfaces()
 	netgear,wndr3700-v5|\
 	netis,wf-2881|\
 	wevo,11acnas|\
-	wevo,w2914ns-v2)
+	wevo,w2914ns-v2|\
+	zio,freezio)
 		ucidef_add_switch "switch0" \
 			"0:lan:4" "1:lan:3" "2:lan:2" "3:lan:1" "4:wan" "6@eth0"
 		;;
@@ -241,7 +242,8 @@ ramips_setup_macs()
 		wan_mac=$(macaddr_add "$(mtd_get_mac_binary factory 0x22)" 1)
 		;;
 	wevo,11acnas|\
-	wevo,w2914ns-v2)
+	wevo,w2914ns-v2|\
+	zio,freezio)
 		wan_mac=$(mtd_get_mac_binary factory 0x2e)
 		label_mac=$wan_mac
 		;;