ramips: add support for Asus RT-AC51U

Specification:
 - SoC: MediaTek MT7620A (580 MHz)
 - RAM: 64 MiB (Winbond W9751G6JB-25)
 - Flash: 16 MiB (Spansion S25FL128SAIF00)
 - LAN: x4 100M
 - WAN: x1 100M
 - Others: USB 2.0, reset button, wps button and 9 LEDs

Issues:
 - 5 GHz band is not functional (missing driver support)

Installation:

Asus windows recovery tool:
 - install the Asus firmware restoration utility
 - unplug the router, hold the reset button while powering it on
 - release when the power LED flashes slowly
 - specify a static IP on your computer:
     IP address: 192.168.1.75;
     Subnet mask 255.255.255.0
 - Start the Asus firmware restoration utility, specify the sysupgrade
   image, and press upload

TFTP Recovery method:
 - set computer to a static ip, 192.168.1.75
 - connect computer to the LAN 1 port of the router
 - hold the reset button while powering on the router for a few seconds
 - send firmware image using a tftp client; i.e from linux:
 $ tftp
 tftp> binary
 tftp> connect 192.168.1.1
 tftp> put lede-ramips-mt7620-rt-ac51u-squashfs-sysupgrade.bin
 tftp> quit

Signed-off-by: Ørjan Malde <foxyred333@gmail.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/target/linux/ramips/dts/RT-AC51U.dts b/target/linux/ramips/dts/RT-AC51U.dts
new file mode 100644
index 0000000000..ec313cc5ae
--- /dev/null
+++ b/target/linux/ramips/dts/RT-AC51U.dts
@@ -0,0 +1,126 @@
+/dts-v1/;
+
+#include "mt7620a.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+/ {
+	compatible = "asus,rt-ac51u", "ralink,mt7620a-soc";
+	model = "Asus RT-AC51U";
+
+	gpio-leds {
+		compatible = "gpio-leds";
+
+		power {
+			label = "rt-ac51u:blue:power";
+			gpios = <&gpio0 9 GPIO_ACTIVE_LOW>;
+		};
+
+		usb {
+			label = "rt-ac51u:blue:usb";
+			gpios = <&gpio0 14 GPIO_ACTIVE_LOW>;
+		};
+
+		wifi {
+			label = "rt-ac51u:blue:wifi";
+			gpios = <&gpio3 0 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	gpio-keys-polled {
+		compatible = "gpio-keys-polled";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		poll-interval = <20>;
+
+		reset {
+			label = "reset";
+			gpios = <&gpio0 1 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+
+		wps {
+			label = "wps";
+			gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_WPS_BUTTON>;
+		};
+	};
+
+	gpio_export {
+		compatible = "gpio-export";
+		#size-cells = <0>;
+
+		enable-leds {
+			gpio-export,name = "enable-leds";
+			gpio-export,output = <1>;
+			gpios = <&gpio0 10 GPIO_ACTIVE_HIGH>;
+		};
+	};
+};
+
+&spi0 {
+	status = "okay";
+
+	m25p80@0 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <10000000>;
+
+		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 0x10000>;
+			read-only;
+		};
+
+		partition@50000 {
+			label = "firmware";
+			reg = <0x50000 0xfb0000>;
+		};
+	};
+};
+
+&ehci {
+	status = "okay";
+};
+
+&ohci {
+	status = "okay";
+};
+
+&gpio3 {
+	status = "okay";
+};
+
+&ethernet {
+	status = "okay";
+	mtd-mac-address = <&factory 0x4>;
+	mediatek,portmap = "wllll";
+};
+
+&wmac {
+	ralink,mtd-eeprom = <&factory 0>;
+};
+
+&pinctrl {
+	state_default: pinctrl0 {
+		gpio {
+			ralink,group = "i2c", "wled", "uartf";
+			ralink,function = "gpio";
+		};
+	};
+};