arch/mips/econet/init.c

// 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);
}

/*
 * vsmp_init_secondary expects either GIC or cascading interrupt configuration.
 * The EN751221 is a 34Kc with VEIC, but not GIC compatible. The cascading
 * configuration enables lines 6 and 7 for performance counters, but when this
 * is done on the EN751221 intc with VEIC enabled, it causes the whole intc to
 * stop sending interrupts.
 * Only unmask lines 0 and 1 (software interrupts) in init_secondary.
 */
#ifdef CONFIG_MIPS_MT_SMP
extern const struct plat_smp_ops vsmp_smp_ops;
static struct plat_smp_ops en75_smp_ops __ro_after_init;

static void en751221_init_secondary(void)
{
	write_c0_status((read_c0_status() & ~ST0_IM) |
		(STATUSF_IP0 | STATUSF_IP1));
}

static int __init en751221_register_vsmp_smp_ops(void)
{
	if (!cpu_has_mipsmt)
		return -ENODEV;

	en75_smp_ops = vsmp_smp_ops;
	en75_smp_ops.init_secondary = en751221_init_secondary;
	register_smp_ops(&en75_smp_ops);
	return 0;
}
#else
static int __init en751221_register_vsmp_smp_ops(void)
{
	return -ENODEV;
}
#endif /* CONFIG_MIPS_MT_SMP */

/* 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 ops */
void __init device_tree_init(void)
{
	unflatten_and_copy_device_tree();

	/* EN751221 dual-vpe */
	if (!en751221_register_vsmp_smp_ops())
		return;

	/* EN751221 with MT_SMP disabled */
	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();
}