ath79: add support for MikroTik RouterBOARD 493G (rb4xx series)

This patch adds support for the MikroTik RouterBOARD RB493G, ported
from the ar71xx target.

See https://routerboard.com/RB493G for details

Specification:
- SoC Qualcomm Atheros AR7161
- RAM: 256 MiB
- Storage: 128MiB NAND
- Ethernet: 9x 1000/100/10 Mbps
- USB 1x 2.0 / 1.0 type A
- PCIe: 3x Mini slot
- MicroSD slot

Working:
- Board/system detection
- Ethernet
- SPI
- NAND
- LEDs
- USB
- Sysupgrade

Enabled (but untested due to lack of hardware):
- PCIe - ath79_pci_irq struct has the slot/pin/IRQ mappings if needed

Installation methods:
- tftp boot initramfs image, scp then flash via "sysupgrade -n"
- nand boot existing OpenWrt, scp then flash via "sysupgrade -n"

Notes:
- initramfs image will not work if uncompressed image size over ~8.5Mb
- The "rb4xx" drivers have been enabled

Signed-off-by: Christopher Hill <ch6574@gmail.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/target/linux/ath79/dts/ar7161_mikrotik_routerboard-493g.dts b/target/linux/ath79/dts/ar7161_mikrotik_routerboard-493g.dts
new file mode 100644
index 0000000000..4a5deb8a44
--- /dev/null
+++ b/target/linux/ath79/dts/ar7161_mikrotik_routerboard-493g.dts
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-1.0-or-later OR MIT
+/dts-v1/;
+
+#include "ar7100_mikrotik_routerboard-4xx.dtsi"
+
+/ {
+	compatible = "mikrotik,routerboard-493g", "qca,ar7161";
+	model = "MikroTik RouterBOARD 493G";
+
+	aliases {
+		mdio-gpio0 = &mdio_gpio0;
+	};
+};
+
+&spi {
+	sdcard: mmc-slot@2 {
+		compatible = "mmc-spi-slot";
+
+		reg = <2>;
+		spi-max-frequency = <25000000>;
+	};
+};
+
+&eth1 {
+	status = "okay";
+
+	phy-handle = <&gpio_phy0>;
+
+	mdio_gpio0: mdio-gpio {
+		compatible = "virtual,mdio-gpio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		gpios = <&gpio 7 GPIO_ACTIVE_HIGH>, // MDC
+			<&gpio 8 GPIO_ACTIVE_HIGH>; // MDIO
+
+		gpio_phy0: ethernet-phy@0 {
+			reg = <0>;
+		};
+	};
+};
+
+&usb_phy {
+	status = "okay";
+};
+
+&usb2 {
+	status = "okay";
+};
+
+&usb1 {
+	status = "okay";
+};