mips: dts: Add EcoNet DTS with EN751221 and SmartFiber XP8421-B board

Add DTS files in support of EcoNet platform, including SmartFiber XP8421-B,
a low cost commercially available board based on EN751221.

Signed-off-by: Caleb James DeLisle <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/boot/dts/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 subdir-$(CONFIG_BMIPS_GENERIC)		+= brcm
 subdir-$(CONFIG_CAVIUM_OCTEON_SOC)	+= cavium-octeon
+subdir-$(CONFIG_ECONET)			+= econet
 subdir-$(CONFIG_EYEQ)			+= mobileye
 subdir-$(CONFIG_FIT_IMAGE_FDT_MARDUK)   += img
 subdir-$(CONFIG_FIT_IMAGE_FDT_BOSTON)	+= img

arch/mips/boot/dts/econet/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+dtb-$(CONFIG_DTB_ECONET_SMARTFIBER_XP8421_B)	+= en751221_smartfiber_xp8421-b.dtb

arch/mips/boot/dts/econet/en751221.dtsi

···
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/dts-v1/;
+
+/ {
+	compatible = "econet,en751221";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	hpt_clock: clock {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <200000000>;  /* 200 MHz */
+	};
+
+	cpus: cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu@0 {
+			device_type = "cpu";
+			compatible = "mips,mips24KEc";
+			reg = <0>;
+		};
+	};
+
+	cpuintc: interrupt-controller {
+		compatible = "mti,cpu-interrupt-controller";
+		interrupt-controller;
+		#address-cells = <0>;
+		#interrupt-cells = <1>;
+	};
+
+	intc: interrupt-controller@1fb40000 {
+		compatible = "econet,en751221-intc";
+		reg = <0x1fb40000 0x100>;
+		interrupt-parent = <&cpuintc>;
+		interrupts = <2>;
+
+		interrupt-controller;
+		#interrupt-cells = <1>;
+		econet,shadow-interrupts = <7 2>, <8 3>, <13 12>, <30 29>;
+	};
+
+	uart: serial@1fbf0000 {
+		compatible = "ns16550";
+		reg = <0x1fbf0000 0x30>;
+		reg-io-width = <4>;
+		reg-shift = <2>;
+		interrupt-parent = <&intc>;
+		interrupts = <0>;
+		/*
+		 * Conversion of baud rate to clock frequency requires a
+		 * computation that is not in the ns16550 driver, so this
+		 * uart is fixed at 115200 baud.
+		 */
+		clock-frequency = <1843200>;
+	};
+
+	timer_hpt: timer@1fbf0400 {
+		compatible = "econet,en751221-timer";
+		reg = <0x1fbf0400 0x100>;
+
+		interrupt-parent = <&intc>;
+		interrupts = <30>;
+		clocks = <&hpt_clock>;
+	};
+};

arch/mips/boot/dts/econet/en751221_smartfiber_xp8421-b.dts

···
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/dts-v1/;
+
+#include "en751221.dtsi"
+
+/ {
+	model = "SmartFiber XP8421-B";
+	compatible = "smartfiber,xp8421-b", "econet,en751221";
+
+	memory@0 {
+		device_type = "memory";
+		reg = <0x00000000 0x1c000000>;
+	};
+
+	chosen {
+		stdout-path = "/serial@1fbf0000:115200";
+		linux,usable-memory-range = <0x00020000 0x1bfe0000>;
+	};
+};

arch/mips/econet/Kconfig

···
 
 	config DTB_ECONET_NONE
 		bool "None"
+
+	config DTB_ECONET_SMARTFIBER_XP8421_B
+		bool "EN751221 SmartFiber XP8421-B"
+		depends on SOC_ECONET_EN751221
+		select BUILTIN_DTB
+		help
+		  The SmartFiber XP8421-B is a device based on the EN751221 SoC.
+		  It has 512MB of memory and 256MB of NAND flash. This kernel
+		  needs only an appended initramfs to boot. It can be loaded
+		  through XMODEM and booted from memory in the bootloader, or
+		  it can be packed in tclinux.trx format and written to flash.
 endchoice
 
 endif