riscv: dts: thead: add sipeed Lichee Pi 4A board device tree

Sipeed's Lichee Pi 4A development board uses Lichee Module 4A core
module which is powered by T-HEAD's TH1520 SoC. Add minimal device
tree files for the core module and the development board.

Support basic uart/gpio/dmac drivers, so supports booting to a basic
shell.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

arch/riscv/boot/dts/Makefile

@@ -2,6 +2,7 @@
 subdir-y += allwinner
 subdir-y += sifive
 subdir-y += starfive
+subdir-y += thead
 subdir-y += canaan
 subdir-y += microchip
 subdir-y += renesas

arch/riscv/boot/dts/thead/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+dtb-$(CONFIG_ARCH_THEAD) += th1520-lichee-pi-4a.dtb

arch/riscv/boot/dts/thead/th1520-lichee-module-4a.dtsi

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Jisheng Zhang <jszhang@kernel.org>
+ */
+
+/dts-v1/;
+
+#include "th1520.dtsi"
+
+/ {
+	model = "Sipeed Lichee Module 4A";
+	compatible = "sipeed,lichee-module-4a", "thead,th1520";
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x0 0x00000000 0x2 0x00000000>;
+	};
+};
+
+&osc {
+	clock-frequency = <24000000>;
+};
+
+&osc_32k {
+	clock-frequency = <32768>;
+};
+
+&apb_clk {
+	clock-frequency = <62500000>;
+};
+
+&uart_sclk {
+	clock-frequency = <100000000>;
+};
+
+&dmac0 {
+	status = "okay";
+};

arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Jisheng Zhang <jszhang@kernel.org>
+ */
+
+#include "th1520-lichee-module-4a.dtsi"
+
+/ {
+	model = "Sipeed Lichee Pi 4A";
+	compatible = "sipeed,lichee-pi-4a", "sipeed,lichee-module-4a", "thead,th1520";
+
+	aliases {
+		gpio0 = &gpio0;
+		gpio1 = &gpio1;
+		gpio2 = &gpio2;
+		gpio3 = &gpio3;
+		serial0 = &uart0;
+		serial1 = &uart1;
+		serial2 = &uart2;
+		serial3 = &uart3;
+		serial4 = &uart4;
+		serial5 = &uart5;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+};
+
+&uart0 {
+	status = "okay";
+};