// 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/acpi.h>
#include <linux/arch_topology.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/mm.h>

#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>
#include <asm/irq.h>
#include <asm/mmu_context.h>
#include <asm/numa.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <uapi/asm/hwcap.h>
#include <asm/vector.h>

#include "head.h"

#ifndef CONFIG_HOTPLUG_PARALLEL
static DECLARE_COMPLETION(cpu_running);
#endif

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        int cpuid;
        unsigned int curr_cpuid;

        init_cpu_topology();

        curr_cpuid = smp_processor_id();
        store_cpu_topology(curr_cpuid);
        numa_store_cpu_info(curr_cpuid);
        numa_add_cpu(curr_cpuid);

        /* This covers non-smp usecase mandated by "nosmp" option */
        if (max_cpus == 0)
                return;

        for_each_possible_cpu(cpuid) {
                if (cpuid == curr_cpuid)
                        continue;
                set_cpu_present(cpuid, true);
                numa_store_cpu_info(cpuid);
        }
}

#ifdef CONFIG_ACPI
static unsigned int cpu_count = 1;

static int __init acpi_parse_rintc(union acpi_subtable_headers *header, const unsigned long end)
{
        unsigned long hart;
        static bool found_boot_cpu;
        struct acpi_madt_rintc *processor = (struct acpi_madt_rintc *)header;

        /*
         * Each RINTC structure in MADT will have a flag. If ACPI_MADT_ENABLED
         * bit in the flag is not enabled, it means OS should not try to enable
         * the cpu to which RINTC belongs.
         */
        if (!(processor->flags & ACPI_MADT_ENABLED))
                return 0;

        if (BAD_MADT_ENTRY(processor, end))
                return -EINVAL;

        acpi_table_print_madt_entry(&header->common);

        hart = processor->hart_id;
        if (hart == INVALID_HARTID) {
                pr_warn("Invalid hartid\n");
                return 0;
        }

        if (hart == cpuid_to_hartid_map(0)) {
                BUG_ON(found_boot_cpu);
                found_boot_cpu = true;
                return 0;
        }

        if (cpu_count >= NR_CPUS) {
                pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
                return 0;
        }

        cpuid_to_hartid_map(cpu_count) = hart;
        cpu_count++;

        return 0;
}

static void __init acpi_parse_and_init_cpus(void)
{
        acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC, acpi_parse_rintc, 0);
}
#else
#define acpi_parse_and_init_cpus(...)   do { } while (0)
#endif

static void __init of_parse_and_init_cpus(void)
{
        struct device_node *dn;
        unsigned long hart;
        bool found_boot_cpu = false;
        int cpuid = 1;
        int rc;

        for_each_of_cpu_node(dn) {
                rc = riscv_early_of_processor_hartid(dn, &hart);
                if (rc < 0)
                        continue;

                if (hart == cpuid_to_hartid_map(0)) {
                        BUG_ON(found_boot_cpu);
                        found_boot_cpu = 1;
                        early_map_cpu_to_node(0, of_node_to_nid(dn));
                        continue;
                }
                if (cpuid >= NR_CPUS) {
                        pr_warn("Invalid cpuid [%d] for hartid [%lu]\n",
                                cpuid, hart);
                        continue;
                }

                cpuid_to_hartid_map(cpuid) = hart;
                early_map_cpu_to_node(cpuid, of_node_to_nid(dn));
                cpuid++;
        }

        BUG_ON(!found_boot_cpu);

        if (cpuid > nr_cpu_ids)
                pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
                        cpuid, nr_cpu_ids);
}

void __init setup_smp(void)
{
        int cpuid;

        cpu_set_ops();

        if (acpi_disabled)
                of_parse_and_init_cpus();
        else
                acpi_parse_and_init_cpus();

        for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++)
                if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID)
                        set_cpu_possible(cpuid, true);
}

static int start_secondary_cpu(int cpu, struct task_struct *tidle)
{
        if (cpu_ops->cpu_start)
                return cpu_ops->cpu_start(cpu, tidle);

        return -EOPNOTSUPP;
}

#ifdef CONFIG_HOTPLUG_PARALLEL
int arch_cpuhp_kick_ap_alive(unsigned int cpu, struct task_struct *tidle)
{
        return start_secondary_cpu(cpu, tidle);
}
#else
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
        int ret = 0;
        tidle->thread_info.cpu = cpu;

        ret = start_secondary_cpu(cpu, tidle);
        if (!ret) {
                wait_for_completion_timeout(&cpu_running,
                                            msecs_to_jiffies(1000));

                if (!cpu_online(cpu)) {
                        pr_crit("CPU%u: failed to come online\n", cpu);
                        ret = -EIO;
                }
        } else {
                pr_crit("CPU%u: failed to start\n", cpu);
        }

        return ret;
}
#endif

void __init smp_cpus_done(unsigned int max_cpus)
{
}

/*
 * C entry point for a secondary processor.
 */
asmlinkage __visible void smp_callin(void)
{
        struct mm_struct *mm = &init_mm;
        unsigned int curr_cpuid = smp_processor_id();

        if (has_vector()) {
                /*
                 * Return as early as possible so the hart with a mismatching
                 * vlen won't boot.
                 */
                if (riscv_v_setup_vsize())
                        return;
        }

        /* All kernel threads share the same mm context.  */
        mmgrab(mm);
        current->active_mm = mm;

#ifdef CONFIG_HOTPLUG_PARALLEL
        cpuhp_ap_sync_alive();
#endif

        store_cpu_topology(curr_cpuid);
        notify_cpu_starting(curr_cpuid);

        riscv_ipi_enable();

        numa_add_cpu(curr_cpuid);

        pr_debug("CPU%u: Booted secondary hartid %lu\n", curr_cpuid,
                cpuid_to_hartid_map(curr_cpuid));

        set_cpu_online(curr_cpuid, true);

        /*
         * Remote cache and TLB flushes are ignored while the CPU is offline,
         * so flush them both right now just in case.
         */
        local_flush_icache_all();
        local_flush_tlb_all();
#ifndef CONFIG_HOTPLUG_PARALLEL
        complete(&cpu_running);
#endif
        /*
         * Disable preemption before enabling interrupts, so we don't try to
         * schedule a CPU that hasn't actually started yet.
         */
        local_irq_enable();
        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}