ramips: add support for HUMAX E2

HUMAX E2 (also known as HUMAX QUANTUM E2) is a 2.4/5GHz band AC router,
based on MediaTek MT7620A.

Specifications:
- SoC: MT7620A
- RAM: DDR2 64MB
- Flash: SPI NOR 8MB (MXIC MX25L6405D)
- WiFi:
  - 2.4GHz: SoC internal
  - 5GHz: MT7610E
- Ethernet: 1x 10/100Mbps
  - Switch: SoC internal
- UART: J2 (57600 8N1)
  - pinout: [3V3] (RXD) (GND) (TXD)

Installation and Recovery via TFTP:
1. Connect ethernet cable between Router port and PC Ethernet port.
2. Set your computer to a static IP **192.168.1.1**
3. Turn the device off and wait a few seconds. Hold the WPS button on front
   of device and insert power.
4. Send a firmware image to **192.168.1.6** using TFTP.
   You can use any TFTP client. (tftp, curl, Tftpd64...)
5. Wait until Power LED stop flashing. **DO NOT TURN OFF DEVICE!**
   The device will be automatically rebooted.

Signed-off-by: Kyoungkyu Park <choryu.park@choryu.space>

1 files changed, 142 insertions, 0 deletions

diff --git a/target/linux/ramips/dts/mt7620a_humax_e2.dts b/target/linux/ramips/dts/mt7620a_humax_e2.dts
new file mode 100644
index 0000000000..2a2ad9043d
--- /dev/null
+++ b/target/linux/ramips/dts/mt7620a_humax_e2.dts
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "mt7620a.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+#include <dt-bindings/mtd/partitions/uimage.h>
+
+/ {
+	compatible = "humax,e2", "ralink,mt7620a-soc";
+	model = "HUMAX E2";
+
+	aliases {
+		led-boot = &led_power;
+		led-failsafe = &led_power;
+		led-running = &led_power;
+		led-upgrade = &led_power;
+		label-mac-device = &ethernet;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		led_power: power {
+			label = "green:power";
+			gpios = <&gpio1 3 GPIO_ACTIVE_LOW>;
+		};
+
+		pairing {
+			label = "green:pairing";
+			gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
+		};
+
+		wlan {
+			label = "green:wlan";
+			gpios = <&gpio1 9 GPIO_ACTIVE_LOW>;
+		};
+
+		lan {
+			label = "green:lan";
+			gpios = <&gpio1 4 GPIO_ACTIVE_LOW>;
+		};
+
+		wps {
+			label = "green:wps";
+			gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			gpios = <&gpio1 1 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+	};
+};
+
+&gpio1 {
+	status = "okay";
+};
+
+&spi0 {
+	status = "okay";
+
+	flash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <50000000>;
+
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				label = "u-boot";
+				reg = <0x0 0x30000>;
+				read-only;
+			};
+
+			partition@30000 {
+				label = "u-boot-env";
+				reg = <0x30000 0x10000>;
+				read-only;
+			};
+
+			factory: partition@40000 {
+				label = "factory";
+				reg = <0x40000 0x30000>;
+				read-only;
+
+				compatible = "nvmem-cells";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				macaddr_factory_10007: macaddr@10007 {
+					reg = <0x10007 0x6>;
+				};
+			};
+
+			partition@70000 {
+				compatible = "openwrt,uimage", "denx,uimage";
+				openwrt,offset = <FW_EDIMAX_OFFSET>;
+				openwrt,partition-magic = <FW_MAGIC_EDIMAX>;
+				label = "firmware";
+				reg = <0x70000 0x790000>;
+			};
+		};
+	};
+};
+
+&ethernet {
+	nvmem-cells = <&macaddr_factory_10007>;
+	nvmem-cell-names = "mac-address";
+};
+
+&pcie {
+	status = "okay";
+};
+
+&pcie0 {
+	wifi@0,0 {
+		compatible = "mediatek,mt76";
+		reg = <0x0000 0 0 0 0>;
+		mediatek,mtd-eeprom = <&factory 0x8000>;
+		ieee80211-freq-limit = <5000000 6000000>;
+	};
+};
+
+&wmac {
+	ralink,mtd-eeprom = <&factory 0x0>;
+};
+
+&state_default {
+	gpio {
+		groups = "rgmii1";
+		function = "gpio";
+	};
+};