mips: Add EcoNet MIPS platform support

Add platform support for EcoNet MIPS SoCs.

Signed-off-by: Caleb James DeLisle <cjd@cjdns.fr>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Kbuild.platforms

@@ -11,6 +11,7 @@ platform-$(CONFIG_CAVIUM_OCTEON_SOC)	+= cavium-octeon/
 platform-$(CONFIG_EYEQ)			+= mobileye/
 platform-$(CONFIG_MIPS_COBALT)		+= cobalt/
 platform-$(CONFIG_MACH_DECSTATION)	+= dec/
+platform-$(CONFIG_ECONET)		+= econet/
 platform-$(CONFIG_MIPS_GENERIC)		+= generic/
 platform-$(CONFIG_MACH_JAZZ)		+= jazz/
 platform-$(CONFIG_LANTIQ)		+= lantiq/

arch/mips/Kconfig

@@ -391,6 +391,30 @@ config MACH_DECSTATION
 
 	  otherwise choose R3000.
 
+config ECONET
+	bool "EcoNet MIPS family"
+	select BOOT_RAW
+	select CPU_BIG_ENDIAN
+	select DEBUG_ZBOOT
+	select EARLY_PRINTK_8250
+	select ECONET_EN751221_TIMER
+	select SERIAL_OF_PLATFORM
+	select SYS_SUPPORTS_BIG_ENDIAN
+	select SYS_HAS_CPU_MIPS32_R1
+	select SYS_HAS_CPU_MIPS32_R2
+	select SYS_HAS_EARLY_PRINTK
+	select SYS_SUPPORTS_32BIT_KERNEL
+	select SYS_SUPPORTS_MIPS16
+	select SYS_SUPPORTS_ZBOOT_UART16550
+	select USE_GENERIC_EARLY_PRINTK_8250
+	select USE_OF
+	help
+	  EcoNet EN75xx MIPS devices are big endian MIPS machines used
+	  in XPON (fiber) and DSL applications. They have SPI, PCI, USB,
+	  GPIO, and Ethernet, with optional XPON, DSL, and VoIP DSP cores.
+	  Don't confuse these with the Airoha ARM devices sometimes referred
+	  to as "EcoNet", this family is for MIPS based devices only.
+
 config MACH_JAZZ
 	bool "Jazz family of machines"
 	select ARC_MEMORY
@@ -1021,6 +1045,7 @@ source "arch/mips/ath79/Kconfig"
 source "arch/mips/bcm47xx/Kconfig"
 source "arch/mips/bcm63xx/Kconfig"
 source "arch/mips/bmips/Kconfig"
+source "arch/mips/econet/Kconfig"
 source "arch/mips/generic/Kconfig"
 source "arch/mips/ingenic/Kconfig"
 source "arch/mips/jazz/Kconfig"

arch/mips/boot/compressed/uart-16550.c

@@ -20,6 +20,11 @@
 #define PORT(offset) (CKSEG1ADDR(INGENIC_UART_BASE_ADDR) + (4 * offset))
 #endif
 
+#ifdef CONFIG_ECONET
+#define EN75_UART_BASE	0x1fbf0003
+#define PORT(offset)	(CKSEG1ADDR(EN75_UART_BASE) + (4 * (offset)))
+#endif
+
 #ifndef IOTYPE
 #define IOTYPE char
 #endif

arch/mips/econet/Kconfig

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0
+if ECONET
+
+choice
+	prompt "EcoNet SoC selection"
+	default SOC_ECONET_EN751221
+	help
+	  Select EcoNet MIPS SoC type. Individual SoCs within a family are
+	  very similar, so is it enough to select the right family, and
+	  then customize to the specific SoC using the device tree only.
+
+	config SOC_ECONET_EN751221
+		bool "EN751221 family"
+		select COMMON_CLK
+		select ECONET_EN751221_INTC
+		select IRQ_MIPS_CPU
+		select SMP
+		select SMP_UP
+		select SYS_SUPPORTS_SMP
+		help
+		  The EN751221 family includes EN7512, RN7513, EN7521, EN7526.
+		  They are based on single core MIPS 34Kc processors. To boot
+		  this kernel, you will need a device tree such as
+		  MIPS_RAW_APPENDED_DTB=y, and a root filesystem.
+endchoice
+
+choice
+	prompt "Devicetree selection"
+	default DTB_ECONET_NONE
+	help
+	  Select the devicetree.
+
+	config DTB_ECONET_NONE
+		bool "None"
+endchoice
+
+endif

arch/mips/econet/Makefile

@@ -0,0 +1,2 @@
+
+obj-y := init.o

arch/mips/econet/Platform

@@ -0,0 +1,5 @@
+# To address a 7.2MB kernel size limit in the EcoNet SDK bootloader,
+# we put the load address well above where the bootloader loads and then use
+# zboot. So please set CONFIG_ZBOOT_LOAD_ADDRESS to the address where your
+# bootloader actually places the kernel.
+load-$(CONFIG_ECONET)	+= 0xffffffff81000000

arch/mips/econet/init.c

@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * EcoNet setup code
+ *
+ * Copyright (C) 2025 Caleb James DeLisle <cjd@cjdns.fr>
+ */
+
+#include <linux/init.h>
+#include <linux/of_clk.h>
+#include <linux/irqchip.h>
+
+#include <asm/addrspace.h>
+#include <asm/io.h>
+#include <asm/bootinfo.h>
+#include <asm/time.h>
+#include <asm/prom.h>
+#include <asm/smp-ops.h>
+#include <asm/reboot.h>
+
+#define CR_AHB_RSTCR		((void __iomem *)CKSEG1ADDR(0x1fb00040))
+#define RESET			BIT(31)
+
+#define UART_BASE		CKSEG1ADDR(0x1fbf0003)
+#define UART_REG_SHIFT		2
+
+static void hw_reset(char *command)
+{
+	iowrite32(RESET, CR_AHB_RSTCR);
+}
+
+/* 1. Bring up early printk. */
+void __init prom_init(void)
+{
+	setup_8250_early_printk_port(UART_BASE, UART_REG_SHIFT, 0);
+	_machine_restart = hw_reset;
+}
+
+/* 2. Parse the DT and find memory */
+void __init plat_mem_setup(void)
+{
+	void *dtb;
+
+	set_io_port_base(KSEG1);
+
+	dtb = get_fdt();
+	if (!dtb)
+		panic("no dtb found");
+
+	__dt_setup_arch(dtb);
+
+	early_init_dt_scan_memory();
+}
+
+/* 3. Overload __weak device_tree_init(), add SMP_UP ops */
+void __init device_tree_init(void)
+{
+	unflatten_and_copy_device_tree();
+
+	register_up_smp_ops();
+}
+
+const char *get_system_type(void)
+{
+	return "EcoNet-EN75xx";
+}
+
+/* 4. Initialize the IRQ subsystem */
+void __init arch_init_irq(void)
+{
+	irqchip_init();
+}
+
+/* 5. Timers */
+void __init plat_time_init(void)
+{
+	of_clk_init(NULL);
+	timer_probe();
+}