// SPDX-License-Identifier: GPL-2.0-only
/*
 * SMP initialisation and IPI support
 * Based on arch/arm64/kernel/smp.c
 *
 * Copyright (C) 2012 ARM Ltd.
 * Copyright (C) 2015 Regents of the University of California
 * Copyright (C) 2017 SiFive
 */

#include <linux/cpu.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/kgdb.h>
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/irq_work.h>
#include <linux/nmi.h>

#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>

enum ipi_message_type {
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CPU_STOP,
        IPI_CPU_CRASH_STOP,
        IPI_IRQ_WORK,
        IPI_TIMER,
        IPI_CPU_BACKTRACE,
        IPI_KGDB_ROUNDUP,
        IPI_MAX
};

static const char * const ipi_names[] = {
        [IPI_RESCHEDULE]        = "Rescheduling interrupts",
        [IPI_CALL_FUNC]         = "Function call interrupts",
        [IPI_CPU_STOP]          = "CPU stop interrupts",
        [IPI_CPU_CRASH_STOP]    = "CPU stop (for crash dump) interrupts",
        [IPI_IRQ_WORK]          = "IRQ work interrupts",
        [IPI_TIMER]             = "Timer broadcast interrupts",
        [IPI_CPU_BACKTRACE]     = "CPU backtrace interrupts",
        [IPI_KGDB_ROUNDUP]      = "KGDB roundup interrupts",
};

unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
        [0 ... NR_CPUS-1] = INVALID_HARTID
};
EXPORT_SYMBOL_GPL(__cpuid_to_hartid_map);

void __init smp_setup_processor_id(void)
{
        cpuid_to_hartid_map(0) = boot_cpu_hartid;

        pr_info("Booting Linux on hartid %lu\n", boot_cpu_hartid);
}

static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
static int ipi_virq_base __ro_after_init;
static int nr_ipi __ro_after_init = IPI_MAX;
static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;

int riscv_hartid_to_cpuid(unsigned long hartid)
{
        int i;

        for (i = 0; i < NR_CPUS; i++)
                if (cpuid_to_hartid_map(i) == hartid)
                        return i;

        return -ENOENT;
}

static void ipi_stop(void)
{
        set_cpu_online(smp_processor_id(), false);
        while (1)
                wait_for_interrupt();
}

#ifdef CONFIG_KEXEC_CORE
static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);

static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
{
        crash_save_cpu(regs, cpu);

        atomic_dec(&waiting_for_crash_ipi);

        local_irq_disable();

#ifdef CONFIG_HOTPLUG_CPU
        if (cpu_has_hotplug(cpu))
                cpu_ops->cpu_stop();
#endif

        for(;;)
                wait_for_interrupt();
}
#else
static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
{
        unreachable();
}
#endif

static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
{
        __ipi_send_mask(ipi_desc[op], mask);
}

static void send_ipi_single(int cpu, enum ipi_message_type op)
{
        __ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
}

#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
        send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
}
#endif

static irqreturn_t handle_IPI(int irq, void *data)
{
        unsigned int cpu = smp_processor_id();
        int ipi = irq - ipi_virq_base;

        switch (ipi) {
        case IPI_RESCHEDULE:
                scheduler_ipi();
                break;
        case IPI_CALL_FUNC:
                generic_smp_call_function_interrupt();
                break;
        case IPI_CPU_STOP:
                ipi_stop();
                break;
        case IPI_CPU_CRASH_STOP:
                ipi_cpu_crash_stop(cpu, get_irq_regs());
                break;
        case IPI_IRQ_WORK:
                irq_work_run();
                break;
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
        case IPI_TIMER:
                tick_receive_broadcast();
                break;
#endif
        case IPI_CPU_BACKTRACE:
                nmi_cpu_backtrace(get_irq_regs());
                break;
        case IPI_KGDB_ROUNDUP:
                kgdb_nmicallback(cpu, get_irq_regs());
                break;
        default:
                pr_warn("CPU%d: unhandled IPI%d\n", cpu, ipi);
                break;
        }

        return IRQ_HANDLED;
}

void riscv_ipi_enable(void)
{
        int i;

        if (WARN_ON_ONCE(!ipi_virq_base))
                return;

        for (i = 0; i < nr_ipi; i++)
                enable_percpu_irq(ipi_virq_base + i, 0);
}

void riscv_ipi_disable(void)
{
        int i;

        if (WARN_ON_ONCE(!ipi_virq_base))
                return;

        for (i = 0; i < nr_ipi; i++)
                disable_percpu_irq(ipi_virq_base + i);
}

bool riscv_ipi_have_virq_range(void)
{
        return (ipi_virq_base) ? true : false;
}

void riscv_ipi_set_virq_range(int virq, int nr)
{
        int i, err;

        if (WARN_ON(ipi_virq_base))
                return;

        WARN_ON(nr < IPI_MAX);
        nr_ipi = min(nr, IPI_MAX);
        ipi_virq_base = virq;

        /* Request IPIs */
        for (i = 0; i < nr_ipi; i++) {
                err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
                                         ipi_names[i], &ipi_dummy_dev);
                WARN_ON(err);

                ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
                irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
        }

        /* Enabled IPIs for boot CPU immediately */
        riscv_ipi_enable();
}

void show_ipi_stats(struct seq_file *p, int prec)
{
        unsigned int cpu, i;

        for (i = 0; i < IPI_MAX; i++) {
                seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
                           prec >= 4 ? " " : "");
                for_each_online_cpu(cpu)
                        seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
                seq_printf(p, " %s\n", ipi_names[i]);
        }
}

void arch_send_call_function_ipi_mask(struct cpumask *mask)
{
        send_ipi_mask(mask, IPI_CALL_FUNC);
}

void arch_send_call_function_single_ipi(int cpu)
{
        send_ipi_single(cpu, IPI_CALL_FUNC);
}

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
        send_ipi_mask(mask, IPI_TIMER);
}
#endif

void smp_send_stop(void)
{
        unsigned long timeout;

        if (num_online_cpus() > 1) {
                cpumask_t mask;

                cpumask_copy(&mask, cpu_online_mask);
                cpumask_clear_cpu(smp_processor_id(), &mask);

                if (system_state <= SYSTEM_RUNNING)
                        pr_crit("SMP: stopping secondary CPUs\n");
                send_ipi_mask(&mask, IPI_CPU_STOP);
        }

        /* Wait up to one second for other CPUs to stop */
        timeout = USEC_PER_SEC;
        while (num_online_cpus() > 1 && timeout--)
                udelay(1);

        if (num_online_cpus() > 1)
                pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
                           cpumask_pr_args(cpu_online_mask));
}

#ifdef CONFIG_KEXEC_CORE
/*
 * The number of CPUs online, not counting this CPU (which may not be
 * fully online and so not counted in num_online_cpus()).
 */
static inline unsigned int num_other_online_cpus(void)
{
        unsigned int this_cpu_online = cpu_online(smp_processor_id());

        return num_online_cpus() - this_cpu_online;
}

void crash_smp_send_stop(void)
{
        static int cpus_stopped;
        cpumask_t mask;
        unsigned long timeout;

        /*
         * This function can be called twice in panic path, but obviously
         * we execute this only once.
         */
        if (cpus_stopped)
                return;

        cpus_stopped = 1;

        /*
         * If this cpu is the only one alive at this point in time, online or
         * not, there are no stop messages to be sent around, so just back out.
         */
        if (num_other_online_cpus() == 0)
                return;

        cpumask_copy(&mask, cpu_online_mask);
        cpumask_clear_cpu(smp_processor_id(), &mask);

        atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());

        pr_crit("SMP: stopping secondary CPUs\n");
        send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);

        /* Wait up to one second for other CPUs to stop */
        timeout = USEC_PER_SEC;
        while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
                udelay(1);

        if (atomic_read(&waiting_for_crash_ipi) > 0)
                pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
                        cpumask_pr_args(&mask));
}

bool smp_crash_stop_failed(void)
{
        return (atomic_read(&waiting_for_crash_ipi) > 0);
}
#endif

void arch_smp_send_reschedule(int cpu)
{
        send_ipi_single(cpu, IPI_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);

static void riscv_backtrace_ipi(cpumask_t *mask)
{
        send_ipi_mask(mask, IPI_CPU_BACKTRACE);
}

void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
        nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi);
}

#ifdef CONFIG_KGDB
void kgdb_roundup_cpus(void)
{
        int this_cpu = raw_smp_processor_id();
        int cpu;

        for_each_online_cpu(cpu) {
                /* No need to roundup ourselves */
                if (cpu == this_cpu)
                        continue;

                send_ipi_single(cpu, IPI_KGDB_ROUNDUP);
        }
}
#endif