ramips: add support for Kroks Rt-Pot mXw DS RSIM router

Aka "Kroks KNdRt31R19".
Ported from v19.07.8 of OpenWrt fork:
see https://github.com/kroks-free/openwrt
for support of other models.

Device specs:
- CPU: MediaTek MT7628AN
- Flash: 16MB SPI NOR
- RAM: 64MB
- Bootloader: U-Boot
- Ethernet: 1x 10/100 Mbps
- 2.4 GHz: b/g/n SoC
- mPCIe: 1x (usually equipped with an LTE modem by vendor)
- Buttons: reset
- LEDs: 1x Modem, 1x Injector, 1x Wi-Fi, 1x Status

Flashing:
- sysupgrade image via stock firmware WEB interface.
- U-Boot launches a WEB server if Reset button is held during power up.
Server IP: 192.168.1.1

SIM card switching:
The device supports up to 4 SIM cards - 2 locally on board and 2 on
remote SIM-injector.
By default, 1-st local SIM is active.
To switch to e.g. 1-st remote SIM:
echo 0 > /sys/class/gpio/modem1power/value
echo 0 > /sys/class/gpio/modem1sim1/value
echo 1 > /sys/class/gpio/modem1rsim1/value
echo 1 > /sys/class/gpio/modem1power/value

MAC addresses as verified by OEM firmware:
vendor   OpenWrt   source
LAN      eth0      factory 0x4 (label)
2g       wlan0     label

Signed-off-by: Kroks <dev@kroks.ru>
[butirsky@gmail.com: port to master; drop dts-v1]
Signed-off-by: Andrey Butirsky <butirsky@gmail.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/target/linux/ramips/dts/mt7628an_kroks.dtsi b/target/linux/ramips/dts/mt7628an_kroks.dtsi
new file mode 100644
index 0000000000..dc1eee9cca
--- /dev/null
+++ b/target/linux/ramips/dts/mt7628an_kroks.dtsi
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "mt7628an.dtsi"
+
+#include <dt-bindings/input/input.h>
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	aliases {
+		led-boot = &led_status;
+		led-failsafe = &led_status;
+		led-running = &led_status;
+		led-upgrade = &led_status;
+		serial1 = &uart1;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		led_status: status {
+			label = "led:status";
+			gpios = <&gpio 2 GPIO_ACTIVE_LOW>;
+		};
+
+		wifi {
+			label = "led:wifi";
+			gpios = <&gpio 44 GPIO_ACTIVE_LOW>;
+			linux,default-trigger = "phy0tpt";
+		};
+	};
+
+	keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			gpios = <&gpio 38 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+	};
+};
+
+&spi0 {
+	status = "okay";
+
+	flash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <25000000>;
+		m25p,fast-read;
+
+		partitions: partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				label = "u-boot";
+				reg = <0x0 0x30000>;
+			};
+
+			partition@30000 {
+				label = "u-boot-env";
+				reg = <0x30000 0x10000>;
+			};
+
+			factory: partition@40000 {
+				label = "factory";
+				reg = <0x40000 0x10000>;
+			};
+
+			partition@50000 {
+				compatible = "denx,uimage";
+				label = "firmware";
+				reg = <0x50000 0xfb0000>;
+			};
+		};
+	};
+};
+
+&state_default {
+	gpio_reset {
+		groups = "wdt";
+		function = "gpio";
+	};
+
+	p0led_an {
+		groups = "p0led_an";
+		function = "p0led_an";
+	};
+};
+
+&factory {
+	compatible = "nvmem-cells";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	macaddr_factory_4: macaddr@4 {
+		reg = <0x4 0x6>;
+	};
+};
+
+&ethernet {
+	nvmem-cells = <&macaddr_factory_4>;
+	nvmem-cell-names = "mac-address";
+};
+
+&wmac {
+	status = "okay";
+
+	mediatek,mtd-eeprom = <&factory 0x0000>;
+};
+
+&uart1 {
+	status = "okay";
+};