// SPDX-License-Identifier: GPL-2.0
/*
 * SMP support for SoCs with APMU
 *
 * Copyright (C) 2014  Renesas Electronics Corporation
 * Copyright (C) 2013  Magnus Damm
 */
#include <linux/cpu_pm.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/smp.h>
#include <linux/suspend.h>
#include <linux/threads.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/proc-fns.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include "common.h"
#include "rcar-gen2.h"

static struct {
        void __iomem *iomem;
        int bit;
} apmu_cpus[NR_CPUS];

#define WUPCR_OFFS       0x10           /* Wake Up Control Register */
#define PSTR_OFFS        0x40           /* Power Status Register */
#define CPUNCR_OFFS(n)  (0x100 + (0x10 * (n)))
                                        /* CPUn Power Status Control Register */
#define DBGRCR_OFFS     0x180           /* Debug Resource Reset Control Reg. */

/* Power Status Register */
#define CPUNST(r, n)    (((r) >> (n * 4)) & 3)  /* CPUn Status Bit */
#define CPUST_RUN       0               /* Run Mode */
#define CPUST_STANDBY   3               /* CoreStandby Mode */

/* Debug Resource Reset Control Register */
#define DBGCPUREN       BIT(24)         /* CPU Other Reset Request Enable */
#define DBGCPUNREN(n)   BIT((n) + 20)   /* CPUn Reset Request Enable */
#define DBGCPUPREN      BIT(19)         /* CPU Peripheral Reset Req. Enable */

static int __maybe_unused apmu_power_on(void __iomem *p, int bit)
{
        /* request power on */
        writel_relaxed(BIT(bit), p + WUPCR_OFFS);

        /* wait for APMU to finish */
        while (readl_relaxed(p + WUPCR_OFFS) != 0)
                ;

        return 0;
}

static int __maybe_unused apmu_power_off(void __iomem *p, int bit)
{
        /* request Core Standby for next WFI */
        writel_relaxed(3, p + CPUNCR_OFFS(bit));
        return 0;
}

static int __maybe_unused apmu_power_off_poll(void __iomem *p, int bit)
{
        int k;

        for (k = 0; k < 1000; k++) {
                if (CPUNST(readl_relaxed(p + PSTR_OFFS), bit) == CPUST_STANDBY)
                        return 1;

                mdelay(1);
        }

        return 0;
}

static int __maybe_unused apmu_wrap(int cpu, int (*fn)(void __iomem *p, int cpu))
{
        void __iomem *p = apmu_cpus[cpu].iomem;

        return p ? fn(p, apmu_cpus[cpu].bit) : -EINVAL;
}

#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_SUSPEND)
/* nicked from arch/arm/mach-exynos/hotplug.c */
static inline void cpu_enter_lowpower_a15(void)
{
        unsigned int v;

        asm volatile(
        "       mrc     p15, 0, %0, c1, c0, 0\n"
        "       bic     %0, %0, %1\n"
        "       mcr     p15, 0, %0, c1, c0, 0\n"
                : "=&r" (v)
                : "Ir" (CR_C)
                : "cc");

        flush_cache_louis();

        asm volatile(
        /*
         * Turn off coherency
         */
        "       mrc     p15, 0, %0, c1, c0, 1\n"
        "       bic     %0, %0, %1\n"
        "       mcr     p15, 0, %0, c1, c0, 1\n"
                : "=&r" (v)
                : "Ir" (0x40)
                : "cc");

        isb();
        dsb();
}

static void shmobile_smp_apmu_cpu_shutdown(unsigned int cpu)
{

        /* Select next sleep mode using the APMU */
        apmu_wrap(cpu, apmu_power_off);

        /* Do ARM specific CPU shutdown */
        cpu_enter_lowpower_a15();
}
#endif

#if defined(CONFIG_HOTPLUG_CPU)
static void shmobile_smp_apmu_cpu_die(unsigned int cpu)
{
        /* For this particular CPU deregister boot vector */
        shmobile_smp_hook(cpu, 0, 0);

        /* Shutdown CPU core */
        shmobile_smp_apmu_cpu_shutdown(cpu);

        /* jump to shared mach-shmobile sleep / reset code */
        shmobile_smp_sleep();
}

static int shmobile_smp_apmu_cpu_kill(unsigned int cpu)
{
        return apmu_wrap(cpu, apmu_power_off_poll);
}
#endif

#if defined(CONFIG_SUSPEND)
static int shmobile_smp_apmu_do_suspend(unsigned long cpu)
{
        shmobile_smp_hook(cpu, __pa_symbol(cpu_resume), 0);
        shmobile_smp_apmu_cpu_shutdown(cpu);
        cpu_do_idle(); /* WFI selects Core Standby */
        return 1;
}

static inline void cpu_leave_lowpower(void)
{
        unsigned int v;

        asm volatile("mrc    p15, 0, %0, c1, c0, 0\n"
                     "       orr     %0, %0, %1\n"
                     "       mcr     p15, 0, %0, c1, c0, 0\n"
                     "       mrc     p15, 0, %0, c1, c0, 1\n"
                     "       orr     %0, %0, %2\n"
                     "       mcr     p15, 0, %0, c1, c0, 1\n"
                     : "=&r" (v)
                     : "Ir" (CR_C), "Ir" (0x40)
                     : "cc");
}

static int shmobile_smp_apmu_enter_suspend(suspend_state_t state)
{
        cpu_suspend(smp_processor_id(), shmobile_smp_apmu_do_suspend);
        cpu_leave_lowpower();
        return 0;
}

void __init shmobile_smp_apmu_suspend_init(void)
{
        shmobile_suspend_ops.enter = shmobile_smp_apmu_enter_suspend;
}
#endif

#ifdef CONFIG_SMP
static void apmu_init_cpu(struct resource *res, int cpu, int bit)
{
        u32 x;

        if ((cpu >= ARRAY_SIZE(apmu_cpus)) || apmu_cpus[cpu].iomem)
                return;

        apmu_cpus[cpu].iomem = ioremap(res->start, resource_size(res));
        apmu_cpus[cpu].bit = bit;

        pr_debug("apmu ioremap %d %d %pr\n", cpu, bit, res);

        /* Setup for debug mode */
        x = readl(apmu_cpus[cpu].iomem + DBGRCR_OFFS);
        x |= DBGCPUREN | DBGCPUNREN(bit) | DBGCPUPREN;
        writel(x, apmu_cpus[cpu].iomem + DBGRCR_OFFS);
}

static const struct of_device_id apmu_ids[] = {
        { .compatible = "renesas,apmu" },
        { /*sentinel*/ }
};

static void apmu_parse_dt(void (*fn)(struct resource *res, int cpu, int bit))
{
        struct device_node *np_apmu, *np_cpu;
        struct resource res;
        int bit, index;

        for_each_matching_node(np_apmu, apmu_ids) {
                /* only enable the cluster that includes the boot CPU */
                bool is_allowed = false;

                for (bit = 0; bit < CONFIG_NR_CPUS; bit++) {
                        np_cpu = of_parse_phandle(np_apmu, "cpus", bit);
                        if (!np_cpu)
                                break;
                        if (of_cpu_node_to_id(np_cpu) == 0) {
                                is_allowed = true;
                                of_node_put(np_cpu);
                                break;
                        }
                        of_node_put(np_cpu);
                }
                if (!is_allowed)
                        continue;

                for (bit = 0; bit < CONFIG_NR_CPUS; bit++) {
                        np_cpu = of_parse_phandle(np_apmu, "cpus", bit);
                        if (!np_cpu)
                                break;

                        index = of_cpu_node_to_id(np_cpu);
                        if ((index >= 0) &&
                            !of_address_to_resource(np_apmu, 0, &res))
                                fn(&res, index, bit);

                        of_node_put(np_cpu);
                }
        }
}

static void __init shmobile_smp_apmu_setup_boot(void)
{
        /* install boot code shared by all CPUs */
        shmobile_boot_fn = __pa_symbol(shmobile_smp_boot);
        shmobile_boot_fn_gen2 = shmobile_boot_fn;
}

static int shmobile_smp_apmu_boot_secondary(unsigned int cpu,
                                            struct task_struct *idle)
{
        /* For this particular CPU register boot vector */
        shmobile_smp_hook(cpu, __pa_symbol(shmobile_boot_apmu), 0);

        return apmu_wrap(cpu, apmu_power_on);
}

static void __init shmobile_smp_apmu_prepare_cpus_dt(unsigned int max_cpus)
{
        shmobile_smp_apmu_setup_boot();
        apmu_parse_dt(apmu_init_cpu);
        rcar_gen2_pm_init();
}

static struct smp_operations apmu_smp_ops __initdata = {
        .smp_prepare_cpus       = shmobile_smp_apmu_prepare_cpus_dt,
        .smp_boot_secondary     = shmobile_smp_apmu_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_can_disable        = shmobile_smp_cpu_can_disable,
        .cpu_die                = shmobile_smp_apmu_cpu_die,
        .cpu_kill               = shmobile_smp_apmu_cpu_kill,
#endif
};

CPU_METHOD_OF_DECLARE(shmobile_smp_apmu, "renesas,apmu", &apmu_smp_ops);
#endif /* CONFIG_SMP */