ramips: add support for Ubiquiti UniFi FlexHD

Hardware
--------

- SoC: MediaTek MT7621AT with 128 MiB RAM and 32 MiB Flash
- Wi-Fi: MediaTek MT7603 (b/g/n, 2x2) and MediaTek MT7615 (ac, 4x4)
- Bluetooth: CSR8811 (internal USB, install kmod-bluetooth)

Installation
------------

1. Connect to the booted device at 192.168.1.20 using username/password
   "ubnt".

2. Update the bootloader environment.

   $ fw_setenv devmode TRUE
   $ fw_setenv boot_openwrt "fdt addr \$(fdtcontroladdr);
     fdt rm /signature; bootubnt"
   $ fw_setenv bootcmd "run boot_openwrt"

3. Transfer the OpenWrt sysupgrade image to the device using SCP.

4. Check the mtd partition number for bs / kernel0 / kernel1

   $ cat /proc/mtd

5. Set the bootselect flag to boot from kernel0

   $ dd if=/dev/zero bs=1 count=1 of=/dev/mtdblock4

6. Write the OpenWrt sysupgrade image to both kernel0 as well as kernel1

   $ dd if=openwrt.bin of=/dev/mtdblock6
   $ dd if=openwrt.bin of=/dev/mtdblock7

7. Reboot the device. It should boot into OpenWrt.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
(cherry picked from commit 820f0c07c5)

target/linux/ramips/dts/mt7621_ubnt_unifi-flexhd.dts

@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "mt7621.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+/ {
+	compatible = "ubnt,unifi-flexhd", "mediatek,mt7621-soc";
+	model = "Ubiquiti UniFi FlexHD";
+
+	aliases {
+		label-mac-device = &gmac0;
+		led-boot = &led_blue;
+		led-failsafe = &led_blue;
+		led-running = &led_blue;
+		led-upgrade = &led_blue;
+	};
+
+	chosen {
+		bootargs = "console=ttyS0,115200";
+	};
+
+	keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			gpios = <&gpio 12 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+	};
+};
+
+&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 0x60000>;
+				read-only;
+			};
+
+			partition@60000 {
+				label = "u-boot-env";
+				reg = <0x60000 0x10000>;
+				read-only;
+			};
+
+			factory: partition@70000 {
+				label = "factory";
+				reg = <0x70000 0x10000>;
+				read-only;
+			};
+
+			eeprom: partition@80000 {
+				label = "eeprom";
+				reg = <0x80000 0x10000>;
+				read-only;
+			};
+
+			partition@90000 {
+				label = "bs";
+				reg = <0x90000 0x10000>;
+			};
+
+			partition@a0000 {
+				label = "cfg";
+				reg = <0xa0000 0x100000>;
+				read-only;
+			};
+
+			partition@1a0000 {
+				compatible = "denx,fit";
+				label = "firmware";
+				reg = <0x1a0000 0xf30000>;
+			};
+
+			partition@10d0000 {
+				label = "kernel1";
+				reg = <0x10d0000 0xf30000>;
+				read-only;
+			};
+		};
+	};
+};
+
+&eeprom {
+	compatible = "nvmem-cells";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	macaddr_eeprom_0: macaddr@0 {
+		reg = <0x0 0x6>;
+	};
+};
+
+&gmac0 {
+	nvmem-cells = <&macaddr_eeprom_0>;
+	nvmem-cell-names = "mac-address";
+};
+
+&switch0 {
+	ports {
+		port@0 {
+			status = "okay";
+			label = "lan";
+		};
+	};
+};
+
+&pcie {
+	status = "okay";
+};
+
+&pcie0 {
+	wifi@0,0 {
+		reg = <0x0 0 0 0 0>;
+		mediatek,mtd-eeprom = <&factory 0x0>;
+		// On newer devices there is a MediaTek MAC in the above
+		// device EEPROM, so override it with a calculated one.
+		nvmem-cells = <&macaddr_eeprom_0>;
+		nvmem-cell-names = "mac-address";
+		mac-address-increment = <1>;
+	};
+};
+
+&pcie1 {
+	wifi@0,0 {
+		reg = <0x0 0 0 0 0>;
+		mediatek,mtd-eeprom = <&factory 0x8000>;
+		// On newer devices there is a MediaTek MAC in the above
+		// device EEPROM, so override it with a calculated one.
+		nvmem-cells = <&macaddr_eeprom_0>;
+		nvmem-cell-names = "mac-address";
+		mac-address-increment = <2>;
+	};
+};
+
+&i2c {
+	status = "okay";
+	clock-frequency = <400000>;
+
+	led-controller@30 {
+		compatible = "ubnt,ledbar";
+		reg = <0x30>;
+
+		enable-gpio = <&gpio 44 GPIO_ACTIVE_HIGH>;
+		reset-gpio = <&gpio 41 GPIO_ACTIVE_LOW>;
+		led-count = <8>;
+
+		red {
+			label = "red";
+		};
+
+		green {
+			label = "green";
+		};
+
+		led_blue: blue {
+			label = "blue";
+		};
+	};
+};
+
+&state_default {
+	gpio {
+		groups = "uart2";
+		function = "gpio";
+	};
+};