// SPDX-License-Identifier: GPL-2.0
/*
 *  sun4m SMP support.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 */

#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/profile.h>
#include <linux/delay.h>
#include <linux/sched/mm.h>
#include <linux/cpu.h>

#include <asm/cacheflush.h>
#include <asm/switch_to.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/oplib.h>

#include "irq.h"
#include "kernel.h"

#define IRQ_IPI_SINGLE          12
#define IRQ_IPI_MASK            13
#define IRQ_IPI_RESCHED         14
#define IRQ_CROSS_CALL          15

static inline unsigned long
swap_ulong(volatile unsigned long *ptr, unsigned long val)
{
        __asm__ __volatile__("swap [%1], %0\n\t" :
                             "=&r" (val), "=&r" (ptr) :
                             "0" (val), "1" (ptr));
        return val;
}

void sun4m_cpu_pre_starting(void *arg)
{
}

void sun4m_cpu_pre_online(void *arg)
{
        int cpuid = hard_smp_processor_id();

        /* Allow master to continue. The master will then give us the
         * go-ahead by setting the smp_commenced_mask and will wait without
         * timeouts until our setup is completed fully (signified by
         * our bit being set in the cpu_online_mask).
         */
        swap_ulong(&cpu_callin_map[cpuid], 1);

        /* XXX: What's up with all the flushes? */
        local_ops->cache_all();
        local_ops->tlb_all();

        /* Fix idle thread fields. */
        __asm__ __volatile__("ld [%0], %%g6\n\t"
                             : : "r" (&current_set[cpuid])
                             : "memory" /* paranoid */);

        /* Attach to the address space of init_task. */
        mmgrab(&init_mm);
        current->active_mm = &init_mm;

        while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
                mb();
}

/*
 *      Cycle through the processors asking the PROM to start each one.
 */
void __init smp4m_boot_cpus(void)
{
        sun4m_unmask_profile_irq();
        local_ops->cache_all();
}

int smp4m_boot_one_cpu(int i, struct task_struct *idle)
{
        unsigned long *entry = &sun4m_cpu_startup;
        int timeout;
        int cpu_node;

        cpu_find_by_mid(i, &cpu_node);
        current_set[i] = task_thread_info(idle);

        /* See trampoline.S for details... */
        entry += ((i - 1) * 3);

        /*
         * Initialize the contexts table
         * Since the call to prom_startcpu() trashes the structure,
         * we need to re-initialize it for each cpu
         */
        smp_penguin_ctable.which_io = 0;
        smp_penguin_ctable.phys_addr = (unsigned int) srmmu_ctx_table_phys;
        smp_penguin_ctable.reg_size = 0;

        /* whirrr, whirrr, whirrrrrrrrr... */
        printk(KERN_INFO "Starting CPU %d at %p\n", i, entry);
        local_ops->cache_all();
        prom_startcpu(cpu_node, &smp_penguin_ctable, 0, (char *)entry);

        /* wheee... it's going... */
        for (timeout = 0; timeout < 10000; timeout++) {
                if (cpu_callin_map[i])
                        break;
                udelay(200);
        }

        if (!(cpu_callin_map[i])) {
                printk(KERN_ERR "Processor %d is stuck.\n", i);
                return -ENODEV;
        }

        local_ops->cache_all();
        return 0;
}

void __init smp4m_smp_done(void)
{
        int i, first;
        int *prev;

        /* setup cpu list for irq rotation */
        first = 0;
        prev = &first;
        for_each_online_cpu(i) {
                *prev = i;
                prev = &cpu_data(i).next;
        }
        *prev = first;
        local_ops->cache_all();

        /* Ok, they are spinning and ready to go. */
}

static void sun4m_send_ipi(int cpu, int level)
{
        sbus_writel(SUN4M_SOFT_INT(level), &sun4m_irq_percpu[cpu]->set);
}

static void sun4m_ipi_resched(int cpu)
{
        sun4m_send_ipi(cpu, IRQ_IPI_RESCHED);
}

static void sun4m_ipi_single(int cpu)
{
        sun4m_send_ipi(cpu, IRQ_IPI_SINGLE);
}

static void sun4m_ipi_mask_one(int cpu)
{
        sun4m_send_ipi(cpu, IRQ_IPI_MASK);
}

static struct smp_funcall {
        smpfunc_t func;
        unsigned long arg1;
        unsigned long arg2;
        unsigned long arg3;
        unsigned long arg4;
        unsigned long arg5;
        unsigned long processors_in[SUN4M_NCPUS];  /* Set when ipi entered. */
        unsigned long processors_out[SUN4M_NCPUS]; /* Set when ipi exited. */
} ccall_info;

static DEFINE_SPINLOCK(cross_call_lock);

/* Cross calls must be serialized, at least currently. */
static void sun4m_cross_call(smpfunc_t func, cpumask_t mask, unsigned long arg1,
                             unsigned long arg2, unsigned long arg3,
                             unsigned long arg4)
{
                register int ncpus = SUN4M_NCPUS;
                unsigned long flags;

                spin_lock_irqsave(&cross_call_lock, flags);

                /* Init function glue. */
                ccall_info.func = func;
                ccall_info.arg1 = arg1;
                ccall_info.arg2 = arg2;
                ccall_info.arg3 = arg3;
                ccall_info.arg4 = arg4;
                ccall_info.arg5 = 0;

                /* Init receive/complete mapping, plus fire the IPI's off. */
                {
                        register int i;

                        cpumask_clear_cpu(smp_processor_id(), &mask);
                        cpumask_and(&mask, cpu_online_mask, &mask);
                        for (i = 0; i < ncpus; i++) {
                                if (cpumask_test_cpu(i, &mask)) {
                                        ccall_info.processors_in[i] = 0;
                                        ccall_info.processors_out[i] = 0;
                                        sun4m_send_ipi(i, IRQ_CROSS_CALL);
                                } else {
                                        ccall_info.processors_in[i] = 1;
                                        ccall_info.processors_out[i] = 1;
                                }
                        }
                }

                {
                        register int i;

                        i = 0;
                        do {
                                if (!cpumask_test_cpu(i, &mask))
                                        continue;
                                while (!ccall_info.processors_in[i])
                                        barrier();
                        } while (++i < ncpus);

                        i = 0;
                        do {
                                if (!cpumask_test_cpu(i, &mask))
                                        continue;
                                while (!ccall_info.processors_out[i])
                                        barrier();
                        } while (++i < ncpus);
                }
                spin_unlock_irqrestore(&cross_call_lock, flags);
}

/* Running cross calls. */
void smp4m_cross_call_irq(void)
{
        int i = smp_processor_id();

        ccall_info.processors_in[i] = 1;
        ccall_info.func(ccall_info.arg1, ccall_info.arg2, ccall_info.arg3,
                        ccall_info.arg4, ccall_info.arg5);
        ccall_info.processors_out[i] = 1;
}

void smp4m_percpu_timer_interrupt(struct pt_regs *regs)
{
        struct pt_regs *old_regs;
        struct clock_event_device *ce;
        int cpu = smp_processor_id();

        old_regs = set_irq_regs(regs);

        ce = &per_cpu(sparc32_clockevent, cpu);

        if (clockevent_state_periodic(ce))
                sun4m_clear_profile_irq(cpu);
        else
                sparc_config.load_profile_irq(cpu, 0); /* Is this needless? */

        irq_enter();
        ce->event_handler(ce);
        irq_exit();

        set_irq_regs(old_regs);
}

static const struct sparc32_ipi_ops sun4m_ipi_ops = {
        .cross_call = sun4m_cross_call,
        .resched    = sun4m_ipi_resched,
        .single     = sun4m_ipi_single,
        .mask_one   = sun4m_ipi_mask_one,
};

void __init sun4m_init_smp(void)
{
        sparc32_ipi_ops = &sun4m_ipi_ops;
}