riscv: Add Kendryte K210 device tree

Add a generic device tree for Kendryte K210 SoC based boards. This is
for now a very simple device tree describing the core elements of the
SoC. This is suitable (and tested) for the Kendryte KD233 development
board, the Sipeed MAIX M1 Dan Dock board and the Sipeed MAIXDUINO board.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/boot/dts/Makefile

 # SPDX-License-Identifier: GPL-2.0
 subdir-y += sifive
+subdir-y += kendryte

arch/riscv/boot/dts/kendryte/Makefile

+# SPDX-License-Identifier: GPL-2.0
+dtb-$(CONFIG_SOC_KENDRYTE) += k210.dtb

arch/riscv/boot/dts/kendryte/k210.dts

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+
+/dts-v1/;
+
+#include "k210.dtsi"
+
+/ {
+	model = "Kendryte K210 generic";
+	compatible = "kendryte,k210";
+
+	chosen {
+		bootargs = "earlycon console=ttySIF0";
+		stdout-path = "serial0";
+	};
+};
+
+&uarths0 {
+	status = "okay";
+};
+

arch/riscv/boot/dts/kendryte/k210.dtsi

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Sean Anderson <seanga2@gmail.com>
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+#include <dt-bindings/clock/k210-clk.h>
+
+/ {
+	/*
+	 * Although the K210 is a 64-bit CPU, the address bus is only 32-bits
+	 * wide, and the upper half of all addresses is ignored.
+	 */
+	#address-cells = <1>;
+	#size-cells = <1>;
+	compatible = "kendryte,k210";
+
+	aliases {
+		serial0 = &uarths0;
+	};
+
+	/*
+	 * The K210 has an sv39 MMU following the priviledge specification v1.9.
+	 * Since this is a non-ratified draft specification, the kernel does not
+	 * support it and the K210 support enabled only for the !MMU case.
+	 * Be consistent with this by setting the CPUs MMU type to "none".
+	 */
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		timebase-frequency = <7800000>;
+		cpu0: cpu@0 {
+			device_type = "cpu";
+			reg = <0>;
+			compatible = "kendryte,k210", "sifive,rocket0", "riscv";
+			riscv,isa = "rv64imafdc";
+			mmu-type = "none";
+			i-cache-size = <0x8000>;
+			i-cache-block-size = <64>;
+			d-cache-size = <0x8000>;
+			d-cache-block-size = <64>;
+			clocks = <&sysctl K210_CLK_CPU>;
+			clock-frequency = <390000000>;
+			cpu0_intc: interrupt-controller {
+				#interrupt-cells = <1>;
+				interrupt-controller;
+				compatible = "riscv,cpu-intc";
+			};
+		};
+		cpu1: cpu@1 {
+			device_type = "cpu";
+			reg = <1>;
+			compatible = "kendryte,k210", "sifive,rocket0", "riscv";
+			riscv,isa = "rv64imafdc";
+			mmu-type = "none";
+			i-cache-size = <0x8000>;
+			i-cache-block-size = <64>;
+			d-cache-size = <0x8000>;
+			d-cache-block-size = <64>;
+			clocks = <&sysctl K210_CLK_CPU>;
+			clock-frequency = <390000000>;
+			cpu1_intc: interrupt-controller {
+				#interrupt-cells = <1>;
+				interrupt-controller;
+				compatible = "riscv,cpu-intc";
+			};
+		};
+	};
+
+	sram: memory@80000000 {
+		device_type = "memory";
+		reg = <0x80000000 0x400000>,
+		      <0x80400000 0x200000>,
+		      <0x80600000 0x200000>;
+		reg-names = "sram0", "sram1", "aisram";
+	};
+
+	clocks {
+		in0: oscillator {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+			clock-frequency = <26000000>;
+		};
+	};
+
+	soc {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "kendryte,k210-soc", "simple-bus";
+		ranges;
+		interrupt-parent = <&plic0>;
+
+		sysctl: sysctl@50440000 {
+			compatible = "kendryte,k210-sysctl", "simple-mfd";
+			reg = <0x50440000 0x1000>;
+			#clock-cells = <1>;
+		};
+
+		clint0: interrupt-controller@2000000 {
+			compatible = "riscv,clint0";
+			reg = <0x2000000 0xC000>;
+			interrupts-extended = <&cpu0_intc 3>,  <&cpu1_intc 3>;
+			clocks = <&sysctl K210_CLK_ACLK>;
+		};
+
+		plic0: interrupt-controller@c000000 {
+			#interrupt-cells = <1>;
+			interrupt-controller;
+			compatible = "kendryte,k210-plic0", "riscv,plic0";
+			reg = <0xC000000 0x4000000>;
+			interrupts-extended = <&cpu0_intc 11>, <&cpu0_intc 0xffffffff>,
+					      <&cpu1_intc 11>, <&cpu1_intc 0xffffffff>;
+			riscv,ndev = <65>;
+			riscv,max-priority = <7>;
+		};
+
+		uarths0: serial@38000000 {
+			compatible = "kendryte,k210-uarths", "sifive,uart0";
+			reg = <0x38000000 0x1000>;
+			interrupts = <33>;
+			clocks = <&sysctl K210_CLK_CPU>;
+		};
+	};
+};

include/dt-bindings/clock/k210-clk.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019-20 Sean Anderson <seanga2@gmail.com>
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ */
+#ifndef K210_CLK_H
+#define K210_CLK_H
+
+/*
+ * Arbitrary identifiers for clocks.
+ * The structure is: in0 -> pll0 -> aclk -> cpu
+ *
+ * Since we use the hardware defaults for now, set all these to the same clock.
+ */
+#define K210_CLK_PLL0   0
+#define K210_CLK_PLL1   0
+#define K210_CLK_ACLK   0
+#define K210_CLK_CPU    0
+
+#endif /* K210_CLK_H */