ARM: dts: renesas: Add Renesas Gray Hawk boards support

Initial support for the Renesas Gray Hawk CPU and BreakOut boards.

The arch/arm/dts/r8a779h0-gray-hawk-cpu.dtsi is extended version of:
https://lore.kernel.org/linux-renesas-soc/b657402113267acd57aece0b4c681b707e704455.1706194617.git.geert+renesas@glider.be/
The version currenty submitted upstream lacks functionality which is
present in this series. Once the upstream support implements that
missing functionality, these DTs will be updated to match.

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
diff --git a/arch/arm/dts/r8a779h0-gray-hawk-cpu.dtsi b/arch/arm/dts/r8a779h0-gray-hawk-cpu.dtsi
new file mode 100644
index 0000000..c8a4621
--- /dev/null
+++ b/arch/arm/dts/r8a779h0-gray-hawk-cpu.dtsi
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ * Device Tree Source for the Gray Hawk CPU board
+ *
+ * Copyright (C) 2023 Renesas Electronics Corp.
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+#include "r8a779h0.dtsi"
+
+/ {
+	model = "Renesas Gray Hawk CPU board";
+	compatible = "renesas,grayhawk-cpu", "renesas,r8a779h0";
+
+	aliases {
+		ethernet0 = &avb0;
+		serial0 = &hscif0;
+	};
+
+	chosen {
+		bootargs = "ignore_loglevel";
+		stdout-path = "serial0:921600n8";
+	};
+
+	memory@48000000 {
+		device_type = "memory";
+		/* first 128MB is reserved for secure area. */
+		reg = <0x0 0x48000000 0x0 0x78000000>;
+	};
+
+	memory@480000000 {
+		device_type = "memory";
+		reg = <0x4 0x80000000 0x1 0x80000000>;
+	};
+
+	reg_1p8v: regulator-1p8v {
+			compatible = "regulator-fixed";
+			regulator-name = "fixed-1.8V";
+			regulator-min-microvolt = <1800000>;
+			regulator-max-microvolt = <1800000>;
+			regulator-boot-on;
+			regulator-always-on;
+	};
+
+	reg_3p3v: regulator-3p3v {
+			compatible = "regulator-fixed";
+			regulator-name = "fixed-3.3V";
+			regulator-min-microvolt = <3300000>;
+			regulator-max-microvolt = <3300000>;
+			regulator-boot-on;
+			regulator-always-on;
+	};
+};
+
+&avb0 {
+	pinctrl-0 = <&avb0_pins>;
+	pinctrl-names = "default";
+	phy-handle = <&phy0>;
+	tx-internal-delay-ps = <2000>;
+	status = "okay";
+
+	phy0: ethernet-phy@0 {
+		compatible = "ethernet-phy-id0022.1622",
+			     "ethernet-phy-ieee802.3-c22";
+		rxc-skew-ps = <1500>;
+		reg = <0>;
+		interrupt-parent = <&gpio7>;
+		interrupts = <5 IRQ_TYPE_LEVEL_LOW>;
+		reset-gpios = <&gpio7 10 GPIO_ACTIVE_LOW>;
+	};
+};
+
+&extal_clk {
+	clock-frequency = <16666666>;
+};
+
+&extalr_clk {
+	clock-frequency = <32768>;
+};
+
+&hscif0 {
+	uart-has-rtscts;
+	status = "okay";
+};
+
+&i2c0 {
+	pinctrl-0 = <&i2c0_pins>;
+	pinctrl-names = "default";
+
+	status = "okay";
+	clock-frequency = <400000>;
+
+	eeprom@50 {
+		compatible = "rohm,br24g01", "atmel,24c01";
+		label = "cpu-board";
+		reg = <0x50>;
+		pagesize = <8>;
+	};
+};
+
+&mmc0 {
+	pinctrl-0 = <&mmc_pins>;
+	pinctrl-1 = <&mmc_pins>;
+	pinctrl-names = "default", "state_uhs";
+
+	vmmc-supply = <&reg_3p3v>;
+	vqmmc-supply = <&reg_1p8v>;
+	mmc-hs200-1_8v;
+	mmc-hs400-1_8v;
+	bus-width = <8>;
+	no-sd;
+	no-sdio;
+	non-removable;
+	full-pwr-cycle-in-suspend;
+	status = "okay";
+};
+
+&pfc {
+	pinctrl-0 = <&scif_clk_pins>;
+	pinctrl-names = "default";
+
+	avb0_pins: avb0 {
+		mux {
+			groups = "avb0_link", "avb0_mdio", "avb0_rgmii",
+				 "avb0_txcrefclk";
+			function = "avb0";
+		};
+
+		pins_mdio {
+			groups = "avb0_mdio";
+			drive-strength = <21>;
+		};
+
+		pins_mii {
+			groups = "avb0_rgmii";
+			drive-strength = <21>;
+		};
+	};
+
+	hscif0_pins: hscif0 {
+		groups = "hscif0_data", "hscif0_ctrl";
+		function = "hscif0";
+	};
+
+	i2c0_pins: i2c0 {
+		groups = "i2c0";
+		function = "i2c0";
+	};
+
+	mmc_pins: mmc {
+		groups = "mmc_data8", "mmc_ctrl", "mmc_ds";
+		function = "mmc";
+		power-source = <1800>;
+	};
+
+	scif_clk_pins: scif_clk {
+		groups = "scif_clk";
+		function = "scif_clk";
+	};
+};
+
+&scif_clk {
+	clock-frequency = <24000000>;
+};