/*
 * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
 * Copyright (C) 2017 Stafford Horne <shorne@gmail.com>
 *
 * Based on arm64 and arc implementations
 * Copyright (C) 2013 ARM Ltd.
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2.  This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/irq.h>
#include <asm/cpuinfo.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/time.h>

static void (*smp_cross_call)(const struct cpumask *, unsigned int);

unsigned long secondary_release = -1;
struct thread_info *secondary_thread_info;

enum ipi_msg_type {
        IPI_WAKEUP,
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CALL_FUNC_SINGLE,
};

static DEFINE_SPINLOCK(boot_lock);

static void boot_secondary(unsigned int cpu, struct task_struct *idle)
{
        /*
         * set synchronisation state between this boot processor
         * and the secondary one
         */
        spin_lock(&boot_lock);

        secondary_release = cpu;
        smp_cross_call(cpumask_of(cpu), IPI_WAKEUP);

        /*
         * now the secondary core is starting up let it run its
         * calibrations, then wait for it to finish
         */
        spin_unlock(&boot_lock);
}

void __init smp_prepare_boot_cpu(void)
{
}

void __init smp_init_cpus(void)
{
        int i;

        for (i = 0; i < NR_CPUS; i++)
                set_cpu_possible(i, true);
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        int i;

        /*
         * Initialise the present map, which describes the set of CPUs
         * actually populated at the present time.
         */
        for (i = 0; i < max_cpus; i++)
                set_cpu_present(i, true);
}

void __init smp_cpus_done(unsigned int max_cpus)
{
}

static DECLARE_COMPLETION(cpu_running);

int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
        if (smp_cross_call == NULL) {
                pr_warn("CPU%u: failed to start, IPI controller missing",
                        cpu);
                return -EIO;
        }

        secondary_thread_info = task_thread_info(idle);
        current_pgd[cpu] = init_mm.pgd;

        boot_secondary(cpu, idle);
        if (!wait_for_completion_timeout(&cpu_running,
                                        msecs_to_jiffies(1000))) {
                pr_crit("CPU%u: failed to start\n", cpu);
                return -EIO;
        }
        synchronise_count_master(cpu);

        return 0;
}

asmlinkage __init void secondary_start_kernel(void)
{
        struct mm_struct *mm = &init_mm;
        unsigned int cpu = smp_processor_id();
        /*
         * All kernel threads share the same mm context; grab a
         * reference and switch to it.
         */
        atomic_inc(&mm->mm_count);
        current->active_mm = mm;
        cpumask_set_cpu(cpu, mm_cpumask(mm));

        pr_info("CPU%u: Booted secondary processor\n", cpu);

        setup_cpuinfo();
        openrisc_clockevent_init();

        notify_cpu_starting(cpu);

        /*
         * OK, now it's safe to let the boot CPU continue
         */
        complete(&cpu_running);

        synchronise_count_slave(cpu);
        set_cpu_online(cpu, true);

        local_irq_enable();

        preempt_disable();
        /*
         * OK, it's off to the idle thread for us
         */
        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}

void handle_IPI(unsigned int ipi_msg)
{
        unsigned int cpu = smp_processor_id();

        switch (ipi_msg) {
        case IPI_WAKEUP:
                break;

        case IPI_RESCHEDULE:
                scheduler_ipi();
                break;

        case IPI_CALL_FUNC:
                generic_smp_call_function_interrupt();
                break;

        case IPI_CALL_FUNC_SINGLE:
                generic_smp_call_function_single_interrupt();
                break;

        default:
                WARN(1, "CPU%u: Unknown IPI message 0x%x\n", cpu, ipi_msg);
                break;
        }
}

void smp_send_reschedule(int cpu)
{
        smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

static void stop_this_cpu(void *dummy)
{
        /* Remove this CPU */
        set_cpu_online(smp_processor_id(), false);

        local_irq_disable();
        /* CPU Doze */
        if (mfspr(SPR_UPR) & SPR_UPR_PMP)
                mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
        /* If that didn't work, infinite loop */
        while (1)
                ;
}

void smp_send_stop(void)
{
        smp_call_function(stop_this_cpu, NULL, 0);
}

/* not supported, yet */
int setup_profiling_timer(unsigned int multiplier)
{
        return -EINVAL;
}

void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
        smp_cross_call = fn;
}

void arch_send_call_function_single_ipi(int cpu)
{
        smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}

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

/* TLB flush operations - Performed on each CPU*/
static inline void ipi_flush_tlb_all(void *ignored)
{
        local_flush_tlb_all();
}

void flush_tlb_all(void)
{
        on_each_cpu(ipi_flush_tlb_all, NULL, 1);
}

/*
 * FIXME: implement proper functionality instead of flush_tlb_all.
 * *But*, as things currently stands, the local_tlb_flush_* functions will
 * all boil down to local_tlb_flush_all anyway.
 */
void flush_tlb_mm(struct mm_struct *mm)
{
        on_each_cpu(ipi_flush_tlb_all, NULL, 1);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
        on_each_cpu(ipi_flush_tlb_all, NULL, 1);
}

void flush_tlb_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
        on_each_cpu(ipi_flush_tlb_all, NULL, 1);
}

/* Instruction cache invalidate - performed on each cpu */
static void ipi_icache_page_inv(void *arg)
{
        struct page *page = arg;

        local_icache_page_inv(page);
}

void smp_icache_page_inv(struct page *page)
{
        on_each_cpu(ipi_icache_page_inv, page, 1);
}
EXPORT_SYMBOL(smp_icache_page_inv);