ath79: add support for ZyXEL NWA1121-NI

Specifications:
 * AR9342, 16 MiB Flash, 64 MiB RAM, 802.11n 2T2R, 2.4 GHz
 * 1x Gigabit Ethernet (AR8035), 802.3af PoE

Installation:
* OEM Web UI is at 192.168.1.2
  login as `admin` with password `1234`
* Flash factory-AABJ.bin

The string `AABJ` needs to be present within the file name of the uploaded
image to be accepted by the OEM Web-based updater, the factory image is
named accordingly to save the user from the hassle of manual renaming.

TFTP Recovery:
* Open the case, connect to TTL UART port (this is the official method
  described by Zyxel, the reset button is useless during power-on)
* Extract factory image (.tar.bz2), serve `vmlinux_mi124_f1e.lzma.uImage`
  and `mi124_f1e-jffs2` via tftp at 192.168.1.10
* Interrupt uboot countdown, execute commands
  `run lk`
  `run lf`
  to flash the kernel / filesystem accordingly

MAC addresses as verified by OEM firmware:
use   address   source
LAN   *:cc      mib0 0x30 ('eth0mac'), art 0x1002 (label)
2g    *:cd      mib0 0x4b ('wifi0mac')

Signed-off-by: Sebastian Schaper <openwrt@sebastianschaper.net>

target/linux/ath79/dts/ar9342_zyxel_nwa1121-ni.dts

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "ar9342_zyxel_nwa11xx.dtsi"
+
+/ {
+	compatible = "zyxel,nwa1121-ni", "qca,ar9342";
+	model = "Zyxel NWA1121-NI";
+
+	aliases {
+		label-mac-device = &eth0;
+		led-boot = &led_status_green;
+		led-failsafe = &led_status_amber;
+		led-running = &led_status_green;
+		led-upgrade = &led_status_amber;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		led_status_green: status_green {
+			label = "green:status";
+			gpios = <&gpio 12 GPIO_ACTIVE_LOW>;
+			default-state = "on";
+		};
+
+		led_status_amber: status_amber {
+			label = "amber:status";
+			gpios = <&gpio 11 GPIO_ACTIVE_LOW>;
+		};
+	};
+};

target/linux/ath79/dts/ar9342_zyxel_nwa11xx.dtsi

@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "ar9344.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+#include <dt-bindings/mtd/partitions/uimage.h>
+
+/ {
+	keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			linux,code = <KEY_RESTART>;
+			gpios = <&gpio 4 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	virtual_flash {
+		compatible = "mtd-concat";
+
+		devices = <&fwconcat0 &fwconcat1>;
+
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				compatible = "openwrt,uimage", "denx,uimage";
+				openwrt,ih-magic = <IH_MAGIC_OKLI>;
+				label = "firmware";
+				reg = <0x0 0x0>;
+			};
+		};
+	};
+};
+
+&ref {
+	clock-frequency = <40000000>;
+};
+
+&spi {
+	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 = <0x000000 0x040000>;
+				read-only;
+			};
+
+			partition@40000 {
+				label = "u-boot-env";
+				reg = <0x040000 0x010000>;
+			};
+
+			fwconcat0: partition@50000 {
+				label = "fwconcat0";
+				reg = <0x050000 0x800000>;
+			};
+
+			partition@850000 {
+				label = "loader";
+				reg = <0x850000 0x010000>;
+				read-only;
+			};
+
+			fwconcat1: partition@860000 {
+				label = "fwconcat1";
+				reg = <0x860000 0x740000>;
+			};
+
+			partition@fa0000 {
+				label = "config";
+				reg = <0xfa0000 0x040000>;
+				read-only;
+			};
+
+			partition@fe0000 {
+				label = "mib0";
+				reg = <0xfe0000 0x010000>;
+				read-only;
+
+				compatible = "nvmem-cells";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				macaddr_mib0_4b: macaddr@4b {
+					reg = <0x4b 0x11>;
+				};
+
+				macaddr_mib0_66: macaddr@66 {
+					reg = <0x66 0x11>;
+				};
+			};
+
+			art: partition@ff0000 {
+				label = "art";
+				reg = <0xff0000 0x010000>;
+				read-only;
+
+				compatible = "nvmem-cells";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				calibration_ath9k: calibration@1000 {
+					reg = <0x1000 0x440>;
+				};
+
+				macaddr_art_1002: macaddr@1002 {
+					reg = <0x1002 0x6>;
+				};
+			};
+		};
+	};
+};
+
+&mdio0 {
+	status = "okay";
+
+	phy0: ethernet-phy@0 {
+		reg = <0>;
+		phy-mode = "rgmii";
+	};
+};
+
+&eth0 {
+	status = "okay";
+
+	pll-data = <0x06000000 0x00000101 0x00001313>;
+
+	nvmem-cells = <&macaddr_art_1002>;
+	nvmem-cell-names = "mac-address";
+
+	phy-mode = "rgmii-id";
+	phy-handle = <&phy0>;
+
+	gmac-config {
+		device = <&gmac>;
+		rxdv-delay = <3>;
+		rxd-delay = <3>;
+		txen-delay = <3>;
+		txd-delay = <3>;
+		rgmii-gmac0 = <1>;
+	};
+};
+
+&wmac {
+	status = "okay";
+
+	ieee80211-freq-limit = <2402000 2482000>;
+
+	nvmem-cells = <&macaddr_mib0_4b>, <&calibration_ath9k>;
+	nvmem-cell-names = "mac-address-ascii", "calibration";
+};