riscv: nx25: dts: Add AE250 dts to support RISC-V

AE250 is the Soc using NX25 cpu core base on RISC-V arch.
Details please see the doc/README.ae250.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Signed-off-by: Greentime Hu <green.hu@gmail.com>

arch/riscv/dts/Makefile

+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+dtb-$(CONFIG_TARGET_NX25_AE250) += ae250.dtb
+targets += $(dtb-y)
+
+DTC_FLAGS += -R 4 -p 0x1000
+
+PHONY += dtbs
+dtbs: $(addprefix $(obj)/, $(dtb-y))
+	@:
+
+clean-files := *.dtb

arch/riscv/dts/ae250.dts

+/dts-v1/;
+/ {
+	compatible = "riscv32 nx25";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	interrupt-parent = <&intc>;
+
+	aliases {
+		uart0 = &serial0;
+		ethernet0 = &mac0;
+		spi0 = &spi;
+	} ;
+
+	chosen {
+		bootargs = "console=ttyS0,38400n8 earlyprintk=uart8250-32bit,0xf0300000 debug loglevel=7";
+		stdout-path = "uart0:38400n8";
+		tick-timer = &timer0;
+	};
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x00000000 0x40000000>;
+	};
+
+	spiclk: virt_100mhz {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <100000000>;
+	};
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cpu@0 {
+			compatible = "andestech,n13";
+			reg = <0>;
+			/* FIXME: to fill correct frqeuency */
+			clock-frequency = <60000000>;
+		};
+	};
+
+	intc: interrupt-controller {
+		compatible = "andestech,atnointc010";
+		#interrupt-cells = <1>;
+		interrupt-controller;
+	};
+
+	serial0: serial@f0300000 {
+		compatible = "andestech,uart16550", "ns16550a";
+		reg = <0xf0300000 0x1000>;
+		interrupts = <7 4>;
+		clock-frequency = <19660800>;
+		reg-shift = <2>;
+		reg-offset = <32>;
+		no-loopback-test = <1>;
+	};
+
+	timer0: timer@f0400000 {
+		compatible = "andestech,atcpit100";
+		reg = <0xf0400000 0x1000>;
+		interrupts = <2 4>;
+		clock-frequency = <40000000>;
+	};
+
+	mac0: mac@e0100000 {
+		compatible = "andestech,atmac100";
+		reg = <0xe0100000 0x1000>;
+		interrupts = <25 4>;
+	};
+
+	mmc0: mmc@f0e00000 {
+		compatible = "andestech,atsdc010";
+		max-frequency = <100000000>;
+		fifo-depth = <0x10>;
+		reg = <0xf0e00000 0x1000>;
+		interrupts = <17 4>;
+	};
+
+	spi: spi@f0b00000 {
+		compatible = "andestech,atcspi200";
+		reg = <0xf0b00000 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		num-cs = <1>;
+		clocks = <&spiclk>;
+		interrupts = <3 4>;
+			flash@0 {
+			compatible = "spi-flash";
+			spi-max-frequency = <50000000>;
+			reg = <0>;
+			spi-cpol;
+			spi-cpha;
+		};
+	};
+
+};