arch/sh/kernel/cpu/sh4a/smp-shx3.c

// SPDX-License-Identifier: GPL-2.0
/*
 * SH-X3 SMP
 *
 *  Copyright (C) 2007 - 2010  Paul Mundt
 *  Copyright (C) 2007  Magnus Damm
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <asm/sections.h>

#define STBCR_REG(phys_id) (0xfe400004 | (phys_id << 12))
#define RESET_REG(phys_id) (0xfe400008 | (phys_id << 12))

#define STBCR_MSTP	0x00000001
#define STBCR_RESET	0x00000002
#define STBCR_SLEEP	0x00000004
#define STBCR_LTSLP	0x80000000

static irqreturn_t ipi_interrupt_handler(int irq, void *arg)
{
	unsigned int message = (unsigned int)(long)arg;
	unsigned int cpu = hard_smp_processor_id();
	unsigned int offs = 4 * cpu;
	unsigned int x;

	x = __raw_readl(0xfe410070 + offs); /* C0INITICI..CnINTICI */
	x &= (1 << (message << 2));
	__raw_writel(x, 0xfe410080 + offs); /* C0INTICICLR..CnINTICICLR */

	smp_message_recv(message);

	return IRQ_HANDLED;
}

static void shx3_smp_setup(void)
{
	unsigned int cpu = 0;
	int i, num;

	init_cpu_possible(cpumask_of(cpu));

	/* Enable light sleep for the boot CPU */
	__raw_writel(__raw_readl(STBCR_REG(cpu)) | STBCR_LTSLP, STBCR_REG(cpu));

	__cpu_number_map[0] = 0;
	__cpu_logical_map[0] = 0;

	/*
	 * Do this stupidly for now.. we don't have an easy way to probe
	 * for the total number of cores.
	 */
	for (i = 1, num = 0; i < NR_CPUS; i++) {
		set_cpu_possible(i, true);
		__cpu_number_map[i] = ++num;
		__cpu_logical_map[num] = i;
	}

        printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
}

static void shx3_prepare_cpus(unsigned int max_cpus)
{
	int i;

	BUILD_BUG_ON(SMP_MSG_NR >= 8);

	for (i = 0; i < SMP_MSG_NR; i++)
		if (request_irq(104 + i, ipi_interrupt_handler,
			    IRQF_PERCPU, "IPI", (void *)(long)i))
			pr_err("Failed to request irq %d\n", i);

	for (i = 0; i < max_cpus; i++)
		set_cpu_present(i, true);
}

static void shx3_start_cpu(unsigned int cpu, unsigned long entry_point)
{
	if (__in_29bit_mode())
		__raw_writel(entry_point, RESET_REG(cpu));
	else
		__raw_writel(virt_to_phys(entry_point), RESET_REG(cpu));

	if (!(__raw_readl(STBCR_REG(cpu)) & STBCR_MSTP))
		__raw_writel(STBCR_MSTP, STBCR_REG(cpu));

	while (!(__raw_readl(STBCR_REG(cpu)) & STBCR_MSTP))
		cpu_relax();

	/* Start up secondary processor by sending a reset */
	__raw_writel(STBCR_RESET | STBCR_LTSLP, STBCR_REG(cpu));
}

static unsigned int shx3_smp_processor_id(void)
{
	return __raw_readl(0xff000048); /* CPIDR */
}

static void shx3_send_ipi(unsigned int cpu, unsigned int message)
{
	unsigned long addr = 0xfe410070 + (cpu * 4);

	BUG_ON(cpu >= 4);

	__raw_writel(1 << (message << 2), addr); /* C0INTICI..CnINTICI */
}

static void shx3_update_boot_vector(unsigned int cpu)
{
	__raw_writel(STBCR_MSTP, STBCR_REG(cpu));
	while (!(__raw_readl(STBCR_REG(cpu)) & STBCR_MSTP))
		cpu_relax();
	__raw_writel(STBCR_RESET, STBCR_REG(cpu));
}

static int shx3_cpu_prepare(unsigned int cpu)
{
	shx3_update_boot_vector(cpu);
	return 0;
}

static int register_shx3_cpu_notifier(void)
{
	cpuhp_setup_state_nocalls(CPUHP_SH_SH3X_PREPARE, "sh/shx3:prepare",
				  shx3_cpu_prepare, NULL);
	return 0;
}
late_initcall(register_shx3_cpu_notifier);

struct plat_smp_ops shx3_smp_ops = {
	.smp_setup		= shx3_smp_setup,
	.prepare_cpus		= shx3_prepare_cpus,
	.start_cpu		= shx3_start_cpu,
	.smp_processor_id	= shx3_smp_processor_id,
	.send_ipi		= shx3_send_ipi,
	.cpu_die		= native_cpu_die,
	.cpu_disable		= native_cpu_disable,
	.play_dead		= native_play_dead,
};