ramips: add support for Skylab SKW92A in EVB

Specifically, SKW92A_E16, described here:

  http://www.skylabmodule.com/wp-content/uploads/SkyLab_SKW92A_V1.04_datasheet.pdf

Specification:
- MediaTek MT7628N/N (580 Mhz)
- 64 MB of RAM
- 16 MB of FLASH
- 2T2R 2.4 GHz
- 5x 10/100 Mbps Ethernet
- 2x u.FL
- Power by micro-USB connector at USB1 on EVB
- UART via micro-USB connector at USB3 on EVB (57600 8n1)
- 5x Ethernet LEDs
- 1x WLAN LEDs
- 1x WPS LED connected by jumper wire from I2S_CK on J20 to WPS_LED pin hole next
  to daughter board on EVB
- WPS/Reset button (S2 on EVB)
- RESET button (S1 on EVB) is *not* connected to RST hole next to daughter board

Flash instruction:

>From Skylab firmware:

1. Associate with SKYLAP_AP
2. In a browser, load: http://10.10.10.254/
3. Username/password: admin/admin
4. In web admin interface: Administration / Upload Firmware, browse to
   sysupgrade image, apply, flash will fail with a message:
   Not a valid firmware. *** Warning: "/var/tmpFW" has corrupted data!
5. Telnet to 10.10.10.254, drops you into a root shell with no credentials
6. # cd /var
7. # mtd_write -r write tmpFW mtd4
   Unlocking mtd4 ...
   Writing from tmpFW to mtd4 ... [e]
8. When flash has completed, you will have booted into your firmware.

>From U-boot via TFTP and initramfs:

1. Place openwrt-ramips-mt76x8-skw92a-initramfs-kernel.bin on a TFTP server
2. Connect to serial console at USB3 on EVB
3. Connect ethernet between port 1 (not WAN) and your TFTP server (e.g.
   192.168.11.20)
4. Start terminal software (e.g. screen /dev/ttyUSB0 57600) on PC
5. Apply power to EVB
6. Interrupt u-boot with keypress of "1"
7. At u-boot prompts:
   Input device IP (10.10.10.123) ==:192.168.11.21
   Input server IP (10.10.10.3) ==:192.168.11.20
   Input Linux Kernel filename (root_uImage) ==:openwrt-ramips-mt76x8-skw92a-initramfs-kernel.bin
8. Move ethernet to port 0 (WAN) on EVB
9. At new OpenWrt console shell, fetch squashfs-sysupgrade image and flash
   with sysupgrade.

>From U-boot via TFTP direct flash:

1. Place openwrt-ramips-mt76x8-skw92a-squashfs-sysupgrade.bin on a TFTP server
2. Connect to serial console at USB3 on EVB (57600 8N1)
3. Connect ethernet between port 1 (not WAN) an your TFTP server (e.g.
   192.168.11.20)
4. Start terminal software (e.g. screen /dev/ttyUSB0 57600) on PC
5. Apply power to EVB
6. Interrupt u-boot with keypress of "2"
7. At u-boot prompts:
   Warning!! Erase Linux in Flash then burn new one. Are you sure?(Y/N) Y
   Input device IP (10.10.10.123) ==:192.168.11.21
   Input server IP (10.10.10.3) ==:192.168.11.20
   Input Linux Kernel filename (root_uImage) ==:openwrt-ramips-mt76x8-skw92a-squashfs-sysupgrade.bin
8. When transfer is complete or as OpenWrt begins booting, move ethernet to
   port 0 (WAN).

Signed-off-by: Russell Senior <russell@personaltelco.net>

1 files changed, 120 insertions, 0 deletions

diff --git a/target/linux/ramips/dts/SKW92A.dts b/target/linux/ramips/dts/SKW92A.dts
new file mode 100644
index 0000000000..c43f9e53ea
--- /dev/null
+++ b/target/linux/ramips/dts/SKW92A.dts
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/dts-v1/;
+
+#include "mt7628an.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+/{
+	compatible = "skylab,skw92a", "mediatek,mt7628an-soc";
+	model = "SKW92A";
+
+	aliases {
+		led-boot = &led_power;
+		led-failsafe = &led_power;
+		led-running = &led_power;
+		led-upgrade = &led_power;
+	};
+
+	chosen {
+		bootargs = "console=ttyS0,57600";
+	};
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x0 0x4000000>;
+	};
+
+	gpio-leds {
+		compatible = "gpio-leds";
+
+		led_power: wps {
+			label = "skw92:green:wps";
+			gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	gpio-keys {
+		compatible = "gpio-keys-polled";
+		poll-interval = <20>;
+
+		reset {
+			label = "reset";
+			gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+
+	};
+};
+
+&pinctrl {
+	state_default: pinctrl0 {
+		gpio {
+			ralink,group = "wdt", "refclk", "gpio";
+			ralink,function = "gpio";
+		};
+	};
+};
+
+&ethernet {
+	mtd-mac-address = <&factory 0x28>;
+};
+
+&wmac {
+	status = "okay";
+	ralink,mtd-eeprom = <&factory 0x0>;
+};
+
+&spi0 {
+	status = "okay";
+
+	m25p80@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <10000000>;
+		m25p,chunked-io = <32>;
+
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			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>;
+				compatible = "denx,uimage";
+			};
+		};
+	};
+};
+
+&uart1 {
+	status = "okay";
+};
+
+&ehci {
+	status = "okay";
+};
+
+&ohci {
+	status = "okay";
+};