/*
 * Author: Andy Fleming <afleming@freescale.com>
 *         Kumar Gala <galak@kernel.crashing.org>
 *
 * Copyright 2006-2008, 2011-2012, 2015 Freescale Semiconductor Inc.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/sched/hotplug.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/kexec.h>
#include <linux/highmem.h>
#include <linux/cpu.h>
#include <linux/fsl/guts.h>

#include <asm/machdep.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/mpic.h>
#include <asm/cacheflush.h>
#include <asm/dbell.h>
#include <asm/code-patching.h>
#include <asm/cputhreads.h>
#include <asm/fsl_pm.h>

#include <sysdev/fsl_soc.h>
#include <sysdev/mpic.h>
#include "smp.h"

struct epapr_spin_table {
        u32     addr_h;
        u32     addr_l;
        u32     r3_h;
        u32     r3_l;
        u32     reserved;
        u32     pir;
};

#ifdef CONFIG_HOTPLUG_CPU
static u64 timebase;
static int tb_req;
static int tb_valid;

static void mpc85xx_give_timebase(void)
{
        unsigned long flags;

        local_irq_save(flags);
        hard_irq_disable();

        while (!tb_req)
                barrier();
        tb_req = 0;

        qoriq_pm_ops->freeze_time_base(true);
#ifdef CONFIG_PPC64
        /*
         * e5500/e6500 have a workaround for erratum A-006958 in place
         * that will reread the timebase until TBL is non-zero.
         * That would be a bad thing when the timebase is frozen.
         *
         * Thus, we read it manually, and instead of checking that
         * TBL is non-zero, we ensure that TB does not change.  We don't
         * do that for the main mftb implementation, because it requires
         * a scratch register
         */
        {
                u64 prev;

                asm volatile("mfspr %0, %1" : "=r" (timebase) :
                             "i" (SPRN_TBRL));

                do {
                        prev = timebase;
                        asm volatile("mfspr %0, %1" : "=r" (timebase) :
                                     "i" (SPRN_TBRL));
                } while (prev != timebase);
        }
#else
        timebase = get_tb();
#endif
        mb();
        tb_valid = 1;

        while (tb_valid)
                barrier();

        qoriq_pm_ops->freeze_time_base(false);

        local_irq_restore(flags);
}

static void mpc85xx_take_timebase(void)
{
        unsigned long flags;

        local_irq_save(flags);
        hard_irq_disable();

        tb_req = 1;
        while (!tb_valid)
                barrier();

        set_tb(timebase >> 32, timebase & 0xffffffff);
        isync();
        tb_valid = 0;

        local_irq_restore(flags);
}

static void smp_85xx_mach_cpu_die(void)
{
        unsigned int cpu = smp_processor_id();

        local_irq_disable();
        hard_irq_disable();
        /* mask all irqs to prevent cpu wakeup */
        qoriq_pm_ops->irq_mask(cpu);

        idle_task_exit();

        mtspr(SPRN_TCR, 0);
        mtspr(SPRN_TSR, mfspr(SPRN_TSR));

        generic_set_cpu_dead(cpu);

        cur_cpu_spec->cpu_down_flush();

        qoriq_pm_ops->cpu_die(cpu);

        while (1)
                ;
}

static void qoriq_cpu_kill(unsigned int cpu)
{
        int i;

        for (i = 0; i < 500; i++) {
                if (is_cpu_dead(cpu)) {
#ifdef CONFIG_PPC64
                        paca_ptrs[cpu]->cpu_start = 0;
#endif
                        return;
                }
                msleep(20);
        }
        pr_err("CPU%d didn't die...\n", cpu);
}
#endif

/*
 * To keep it compatible with old boot program which uses
 * cache-inhibit spin table, we need to flush the cache
 * before accessing spin table to invalidate any staled data.
 * We also need to flush the cache after writing to spin
 * table to push data out.
 */
static inline void flush_spin_table(void *spin_table)
{
        flush_dcache_range((ulong)spin_table,
                (ulong)spin_table + sizeof(struct epapr_spin_table));
}

static inline u32 read_spin_table_addr_l(void *spin_table)
{
        flush_dcache_range((ulong)spin_table,
                (ulong)spin_table + sizeof(struct epapr_spin_table));
        return in_be32(&((struct epapr_spin_table *)spin_table)->addr_l);
}

#ifdef CONFIG_PPC64
static void wake_hw_thread(void *info)
{
        void fsl_secondary_thread_init(void);
        unsigned long inia;
        int cpu = *(const int *)info;

        inia = *(unsigned long *)fsl_secondary_thread_init;
        book3e_start_thread(cpu_thread_in_core(cpu), inia);
}
#endif

static int smp_85xx_start_cpu(int cpu)
{
        int ret = 0;
        struct device_node *np;
        const u64 *cpu_rel_addr;
        unsigned long flags;
        int ioremappable;
        int hw_cpu = get_hard_smp_processor_id(cpu);
        struct epapr_spin_table __iomem *spin_table;

        np = of_get_cpu_node(cpu, NULL);
        cpu_rel_addr = of_get_property(np, "cpu-release-addr", NULL);
        if (!cpu_rel_addr) {
                pr_err("No cpu-release-addr for cpu %d\n", cpu);
                return -ENOENT;
        }

        /*
         * A secondary core could be in a spinloop in the bootpage
         * (0xfffff000), somewhere in highmem, or somewhere in lowmem.
         * The bootpage and highmem can be accessed via ioremap(), but
         * we need to directly access the spinloop if its in lowmem.
         */
        ioremappable = *cpu_rel_addr > virt_to_phys(high_memory);

        /* Map the spin table */
        if (ioremappable)
                spin_table = ioremap_prot(*cpu_rel_addr,
                        sizeof(struct epapr_spin_table), _PAGE_COHERENT);
        else
                spin_table = phys_to_virt(*cpu_rel_addr);

        local_irq_save(flags);
        hard_irq_disable();

        if (qoriq_pm_ops)
                qoriq_pm_ops->cpu_up_prepare(cpu);

        /* if cpu is not spinning, reset it */
        if (read_spin_table_addr_l(spin_table) != 1) {
                /*
                 * We don't set the BPTR register here since it already points
                 * to the boot page properly.
                 */
                mpic_reset_core(cpu);

                /*
                 * wait until core is ready...
                 * We need to invalidate the stale data, in case the boot
                 * loader uses a cache-inhibited spin table.
                 */
                if (!spin_event_timeout(
                                read_spin_table_addr_l(spin_table) == 1,
                                10000, 100)) {
                        pr_err("timeout waiting for cpu %d to reset\n",
                                hw_cpu);
                        ret = -EAGAIN;
                        goto err;
                }
        }

        flush_spin_table(spin_table);
        out_be32(&spin_table->pir, hw_cpu);
#ifdef CONFIG_PPC64
        out_be64((u64 *)(&spin_table->addr_h),
                __pa(ppc_function_entry(generic_secondary_smp_init)));
#else
        out_be32(&spin_table->addr_l, __pa(__early_start));
#endif
        flush_spin_table(spin_table);
err:
        local_irq_restore(flags);

        if (ioremappable)
                iounmap(spin_table);

        return ret;
}

static int smp_85xx_kick_cpu(int nr)
{
        int ret = 0;
#ifdef CONFIG_PPC64
        int primary = nr;
#endif

        WARN_ON(nr < 0 || nr >= num_possible_cpus());

        pr_debug("kick CPU #%d\n", nr);

#ifdef CONFIG_PPC64
        if (threads_per_core == 2) {
                if (WARN_ON_ONCE(!cpu_has_feature(CPU_FTR_SMT)))
                        return -ENOENT;

                booting_thread_hwid = cpu_thread_in_core(nr);
                primary = cpu_first_thread_sibling(nr);

                if (qoriq_pm_ops)
                        qoriq_pm_ops->cpu_up_prepare(nr);

                /*
                 * If either thread in the core is online, use it to start
                 * the other.
                 */
                if (cpu_online(primary)) {
                        smp_call_function_single(primary,
                                        wake_hw_thread, &nr, 1);
                        goto done;
                } else if (cpu_online(primary + 1)) {
                        smp_call_function_single(primary + 1,
                                        wake_hw_thread, &nr, 1);
                        goto done;
                }

                /*
                 * If getting here, it means both threads in the core are
                 * offline. So start the primary thread, then it will start
                 * the thread specified in booting_thread_hwid, the one
                 * corresponding to nr.
                 */

        } else if (threads_per_core == 1) {
                /*
                 * If one core has only one thread, set booting_thread_hwid to
                 * an invalid value.
                 */
                booting_thread_hwid = INVALID_THREAD_HWID;

        } else if (threads_per_core > 2) {
                pr_err("Do not support more than 2 threads per CPU.");
                return -EINVAL;
        }

        ret = smp_85xx_start_cpu(primary);
        if (ret)
                return ret;

done:
        paca_ptrs[nr]->cpu_start = 1;
        generic_set_cpu_up(nr);

        return ret;
#else
        ret = smp_85xx_start_cpu(nr);
        if (ret)
                return ret;

        generic_set_cpu_up(nr);

        return ret;
#endif
}

struct smp_ops_t smp_85xx_ops = {
        .cause_nmi_ipi = NULL,
        .kick_cpu = smp_85xx_kick_cpu,
        .cpu_bootable = smp_generic_cpu_bootable,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_disable    = generic_cpu_disable,
        .cpu_die        = generic_cpu_die,
#endif
#if defined(CONFIG_KEXEC_CORE) && !defined(CONFIG_PPC64)
        .give_timebase  = smp_generic_give_timebase,
        .take_timebase  = smp_generic_take_timebase,
#endif
};

#ifdef CONFIG_KEXEC_CORE
#ifdef CONFIG_PPC32
atomic_t kexec_down_cpus = ATOMIC_INIT(0);

void mpc85xx_smp_kexec_cpu_down(int crash_shutdown, int secondary)
{
        local_irq_disable();

        if (secondary) {
                cur_cpu_spec->cpu_down_flush();
                atomic_inc(&kexec_down_cpus);
                /* loop forever */
                while (1);
        }
}

static void mpc85xx_smp_kexec_down(void *arg)
{
        if (ppc_md.kexec_cpu_down)
                ppc_md.kexec_cpu_down(0,1);
}
#else
void mpc85xx_smp_kexec_cpu_down(int crash_shutdown, int secondary)
{
        int cpu = smp_processor_id();
        int sibling = cpu_last_thread_sibling(cpu);
        bool notified = false;
        int disable_cpu;
        int disable_threadbit = 0;
        long start = mftb();
        long now;

        local_irq_disable();
        hard_irq_disable();
        mpic_teardown_this_cpu(secondary);

        if (cpu == crashing_cpu && cpu_thread_in_core(cpu) != 0) {
                /*
                 * We enter the crash kernel on whatever cpu crashed,
                 * even if it's a secondary thread.  If that's the case,
                 * disable the corresponding primary thread.
                 */
                disable_threadbit = 1;
                disable_cpu = cpu_first_thread_sibling(cpu);
        } else if (sibling != crashing_cpu &&
                   cpu_thread_in_core(cpu) == 0 &&
                   cpu_thread_in_core(sibling) != 0) {
                disable_threadbit = 2;
                disable_cpu = sibling;
        }

        if (disable_threadbit) {
                while (paca_ptrs[disable_cpu]->kexec_state < KEXEC_STATE_REAL_MODE) {
                        barrier();
                        now = mftb();
                        if (!notified && now - start > 1000000) {
                                pr_info("%s/%d: waiting for cpu %d to enter KEXEC_STATE_REAL_MODE (%d)\n",
                                        __func__, smp_processor_id(),
                                        disable_cpu,
                                        paca_ptrs[disable_cpu]->kexec_state);
                                notified = true;
                        }
                }

                if (notified) {
                        pr_info("%s: cpu %d done waiting\n",
                                __func__, disable_cpu);
                }

                mtspr(SPRN_TENC, disable_threadbit);
                while (mfspr(SPRN_TENSR) & disable_threadbit)
                        cpu_relax();
        }
}
#endif

static void mpc85xx_smp_machine_kexec(struct kimage *image)
{
#ifdef CONFIG_PPC32
        int timeout = INT_MAX;
        int i, num_cpus = num_present_cpus();

        if (image->type == KEXEC_TYPE_DEFAULT)
                smp_call_function(mpc85xx_smp_kexec_down, NULL, 0);

        while ( (atomic_read(&kexec_down_cpus) != (num_cpus - 1)) &&
                ( timeout > 0 ) )
        {
                timeout--;
        }

        if ( !timeout )
                printk(KERN_ERR "Unable to bring down secondary cpu(s)");

        for_each_online_cpu(i)
        {
                if ( i == smp_processor_id() ) continue;
                mpic_reset_core(i);
        }
#endif

        default_machine_kexec(image);
}
#endif /* CONFIG_KEXEC_CORE */

static void smp_85xx_setup_cpu(int cpu_nr)
{
        mpic_setup_this_cpu();
}

void __init mpc85xx_smp_init(void)
{
        struct device_node *np;


        np = of_find_node_by_type(NULL, "open-pic");
        if (np) {
                smp_85xx_ops.probe = smp_mpic_probe;
                smp_85xx_ops.setup_cpu = smp_85xx_setup_cpu;
                smp_85xx_ops.message_pass = smp_mpic_message_pass;
        } else
                smp_85xx_ops.setup_cpu = NULL;

        if (cpu_has_feature(CPU_FTR_DBELL)) {
                /*
                 * If left NULL, .message_pass defaults to
                 * smp_muxed_ipi_message_pass
                 */
                smp_85xx_ops.message_pass = NULL;
                smp_85xx_ops.cause_ipi = doorbell_global_ipi;
                smp_85xx_ops.probe = NULL;
        }

#ifdef CONFIG_HOTPLUG_CPU
#ifdef CONFIG_FSL_CORENET_RCPM
        fsl_rcpm_init();
#endif

#ifdef CONFIG_FSL_PMC
        mpc85xx_setup_pmc();
#endif
        if (qoriq_pm_ops) {
                smp_85xx_ops.give_timebase = mpc85xx_give_timebase;
                smp_85xx_ops.take_timebase = mpc85xx_take_timebase;
                ppc_md.cpu_die = smp_85xx_mach_cpu_die;
                smp_85xx_ops.cpu_die = qoriq_cpu_kill;
        }
#endif
        smp_ops = &smp_85xx_ops;

#ifdef CONFIG_KEXEC_CORE
        ppc_md.kexec_cpu_down = mpc85xx_smp_kexec_cpu_down;
        ppc_md.machine_kexec = mpc85xx_smp_machine_kexec;
#endif
}