ramips: add support for Ubiquiti USW-Flex

Hardware
--------
MediaTek MT7621AT
16M SPI-NOR Macronix MX25L12835FMI
Microchip PD69104B1 4-Channel PoE-PSE controller
TI TPS2373 PoE-PD controller

PoE-Controller
--------------

By default, the PoE outputs do not work with OpenWrt. To make them output
power, install the "poemgr" package from the packages feed.
This package can control the PD69104B1 PSE controller.

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

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

2. Add the uboot-envtools configuration file /etc/fw_env.config with the
   following content

   $ echo "/dev/mtd1 0x0 0x1000 0x10000 1" > /etc/fw_env.config

3. Update the bootloader environment.

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

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

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

   $ cat /proc/mtd

6. Set the bootselect flag to boot from kernel0

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

7. 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

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

Restore to UniFi
----------------

To restore the vendor firmware, follow the Ubiquiti UniFi TFTP
recovery guide for access points. The process is the same for
the Flex switch.

Signed-off-by: David Bauer <mail@david-bauer.net>

target/linux/ramips/dts/mt7621_ubnt_usw-flex.dts

@@ -0,0 +1,172 @@
+#include "mt7621.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+/ {
+	model = "Ubiquiti UniFi Switch Flex";
+	compatible = "ubnt,usw-flex", "mediatek,mt7621-soc";
+
+	aliases {
+		led-boot = &led_white;
+		led-failsafe = &led_white;
+		led-running = &led_blue;
+		led-upgrade = &led_blue;
+		label-mac-device = &gmac0;
+	};
+
+	chosen {
+		bootargs-override = "console=ttyS0,115200";
+	};
+
+	keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			gpios = <&gpio 12 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		led_blue: status_blue {
+			label = "blue:status";
+			gpios = <&gpio 13 GPIO_ACTIVE_HIGH>;
+		};
+
+		led_white: status_white {
+			label = "white:status";
+			gpios = <&gpio 16 GPIO_ACTIVE_HIGH>;
+		};
+	};
+
+	i2c-gpio {
+		compatible = "i2c-gpio";
+
+		sda-gpios = <&gpio 3 GPIO_ACTIVE_HIGH>;
+		scl-gpios = <&gpio 4 GPIO_ACTIVE_HIGH>;
+
+		i2c-gpio,delay-us = <50>;
+
+		/* Microsemi PD69104B1 PSE controller */
+	};
+};
+
+&gmac0 {
+	nvmem-cells = <&macaddr_eeprom>;
+	nvmem-cell-names = "mac-address";
+	label = "dsa";
+};
+
+&switch0 {
+	ports {
+		port@0 {
+			status = "okay";
+			label = "lan1";
+		};
+
+		port@1 {
+			status = "okay";
+			label = "lan2";
+		};
+
+		port@2 {
+			status = "okay";
+			label = "lan3";
+		};
+
+		port@3 {
+			status = "okay";
+			label = "lan4";
+		};
+
+		port@4 {
+			status = "okay";
+			label = "lan5";
+		};
+	};
+};
+
+&state_default {
+	gpio {
+		groups = "i2c", "uart2", "uart3", "jtag";
+		function = "gpio";
+	};
+};
+
+&spi0 {
+	status = "okay";
+
+	flash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <30000000>;
+
+		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>;
+			};
+
+			partition@70000 {
+				label = "factory";
+				reg = <0x70000 0x10000>;
+				read-only;
+			};
+
+			part_eeprom: partition@80000 {
+				compatible = "nvmem-cells";
+
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				label = "eeprom";
+				reg = <0x80000 0x10000>;
+				read-only;
+
+				macaddr_eeprom: macaddr@0 {
+					reg = <0x0 0x6>;
+				};
+			};
+
+			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 0x730000>;
+			};
+
+			partition@8d0000 {
+				label = "kernel1";
+				reg = <0x8d0000 0x730000>;
+			};
+		};
+	};
+};
+
+&xhci {
+	status = "disabled";
+};