ARM: Add basic support for Airoha EN7523 SoC

EN7523 is an armv8 based silicon used inside broadband access type devices
such as xPON and xDSL. It shares various silicon blocks with MediaTek
silicon such as the MT7622.

Add basic support for Airoha EN7523, enough for booting to console.

The UART is basically 8250-compatible, except for the clock selection.
A clock-frequency value is synthesized to get this to run at 115200 bps.

Signed-off-by: John Crispin <[e-mail]>
Signed-off-by: Bert Vermeulen <[e-mail]>
Signed-off-by: Felix Fietkau <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Matthias Brugger <[e-mail]>

arch/arm/Kconfig

···
 	select HAVE_ARM_ARCH_TIMER
 	select ARCH_SUPPORTS_BIG_ENDIAN
 
+config ARCH_AIROHA
+	bool "Airoha SoC Support"
+	depends on ARCH_MULTI_V7
+	select ARM_AMBA
+	select ARM_GIC
+	select ARM_GIC_V3
+	select ARM_PSCI
+	select HAVE_ARM_ARCH_TIMER
+	select COMMON_CLK
+	help
+	  Support for Airoha EN7523 SoCs
+
 #
 # This is sorted alphabetically by mach-* pathname.  However, plat-*
 # Kconfigs may be included either alphabetically (according to the

arch/arm/Makefile

···
 # Machine directory name.  This list is sorted alphanumerically
 # by CONFIG_* macro name.
 machine-$(CONFIG_ARCH_ACTIONS)		+= actions
+machine-$(CONFIG_ARCH_AIROHA)		+= airoha
 machine-$(CONFIG_ARCH_ALPINE)		+= alpine
 machine-$(CONFIG_ARCH_ARTPEC)		+= artpec
 machine-$(CONFIG_ARCH_ASPEED)           += aspeed

arch/arm/boot/dts/Makefile

···
 	da850-lego-ev3.dtb
 dtb-$(CONFIG_ARCH_DIGICOLOR) += \
 	cx92755_equinox.dtb
+dtb-$(CONFIG_ARCH_AIROHA) += \
+	en7523-evb.dtb
 dtb-$(CONFIG_ARCH_EXYNOS3) += \
 	exynos3250-artik5-eval.dtb \
 	exynos3250-monk.dtb \

arch/arm/boot/dts/en7523-evb.dts

···
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/dts-v1/;
+
+/* Bootloader installs ATF here */
+/memreserve/ 0x80000000 0x200000;
+
+#include "en7523.dtsi"
+
+/ {
+	model = "Airoha EN7523 Evaluation Board";
+	compatible = "airoha,en7523-evb", "airoha,en7523";
+
+	aliases {
+		serial0 = &uart1;
+	};
+
+	chosen {
+		bootargs = "console=ttyS0,115200 earlycon";
+		stdout-path = "serial0:115200n8";
+		linux,usable-memory-range = <0x80200000 0x1fe00000>;
+	};
+
+	memory@80000000 {
+		device_type = "memory";
+		reg = <0x80000000 0x20000000>;
+	};
+};

arch/arm/boot/dts/en7523.dtsi

···
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+#include <dt-bindings/interrupt-controller/irq.h>
+#include <dt-bindings/interrupt-controller/arm-gic.h>
+
+/ {
+	interrupt-parent = <&gic>;
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		npu_binary@84000000 {
+			no-map;
+			reg = <0x84000000 0xA00000>;
+		};
+
+		npu_flag@84B0000 {
+			no-map;
+			reg = <0x84B00000 0x100000>;
+		};
+
+		npu_pkt@85000000 {
+			no-map;
+			reg = <0x85000000 0x1A00000>;
+		};
+
+		npu_phyaddr@86B00000 {
+			no-map;
+			reg = <0x86B00000 0x100000>;
+		};
+
+		npu_rxdesc@86D00000 {
+			no-map;
+			reg = <0x86D00000 0x100000>;
+		};
+	};
+
+	psci {
+		compatible = "arm,psci-0.2";
+		method = "smc";
+	};
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu-map {
+			cluster0 {
+				core0 {
+					cpu = <&cpu0>;
+				};
+				core1 {
+					cpu = <&cpu1>;
+				};
+			};
+		};
+
+		cpu0: cpu@0 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a53";
+			reg = <0x0>;
+			enable-method = "psci";
+			clock-frequency = <80000000>;
+			next-level-cache = <&L2_0>;
+		};
+
+		cpu1: cpu@1 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a53";
+			reg = <0x1>;
+			enable-method = "psci";
+			clock-frequency = <80000000>;
+			next-level-cache = <&L2_0>;
+		};
+
+		L2_0: l2-cache0 {
+			compatible = "cache";
+		};
+	};
+
+	gic: interrupt-controller@9000000 {
+		compatible = "arm,gic-v3";
+		interrupt-controller;
+		#interrupt-cells = <3>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <0x09000000 0x20000>,
+		      <0x09080000 0x80000>,
+		      <0x09400000 0x2000>,
+		      <0x09500000 0x2000>,
+		      <0x09600000 0x20000>;
+		interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_LOW>;
+	};
+
+	timer {
+		compatible = "arm,armv8-timer";
+		interrupt-parent = <&gic>;
+		interrupts = <GIC_PPI 13 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 11 IRQ_TYPE_LEVEL_LOW>,
+			     <GIC_PPI 10 IRQ_TYPE_LEVEL_LOW>;
+	};
+
+	uart1: serial@1fbf0000 {
+		compatible = "ns16550";
+		reg = <0x1fbf0000 0x30>;
+		reg-io-width = <4>;
+		reg-shift = <2>;
+		interrupts = <GIC_SPI 18 IRQ_TYPE_LEVEL_HIGH>;
+		clock-frequency = <1843200>;
+		status = "okay";
+	};
+};

arch/arm/mach-airoha/Makefile

···
+# SPDX-License-Identifier: GPL-2.0-only
+obj-y			+= airoha.o

arch/arm/mach-airoha/airoha.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Device Tree support for Airoha SoCs
+ *
+ * Copyright (c) 2022 Felix Fietkau <[e-mail]>
+ */
+#include <asm/mach/arch.h>
+
+static const char * const airoha_board_dt_compat[] = {
+	"airoha,en7523",
+	NULL,
+};
+
+DT_MACHINE_START(MEDIATEK_DT, "Airoha Cortex-A53 (Device Tree)")
+	.dt_compat	= airoha_board_dt_compat,
+MACHINE_END