/*
 * SMP support for ppc.
 *
 * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
 * deal of code from the sparc and intel versions.
 *
 * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
 *
 * PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 *
 *      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.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/topology.h>

#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputhreads.h>
#include <asm/cputable.h>
#include <asm/system.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#endif

#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

struct thread_info *secondary_ti;

DEFINE_PER_CPU(cpumask_t, cpu_sibling_map) = CPU_MASK_NONE;
DEFINE_PER_CPU(cpumask_t, cpu_core_map) = CPU_MASK_NONE;

EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
EXPORT_PER_CPU_SYMBOL(cpu_core_map);

/* SMP operations for this machine */
struct smp_ops_t *smp_ops;

/* Can't be static due to PowerMac hackery */
volatile unsigned int cpu_callin_map[NR_CPUS];

int smt_enabled_at_boot = 1;

static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;

#ifdef CONFIG_PPC64
void __devinit smp_generic_kick_cpu(int nr)
{
        BUG_ON(nr < 0 || nr >= NR_CPUS);

        /*
         * The processor is currently spinning, waiting for the
         * cpu_start field to become non-zero After we set cpu_start,
         * the processor will continue on to secondary_start
         */
        paca[nr].cpu_start = 1;
        smp_mb();
}
#endif

void smp_message_recv(int msg)
{
        switch(msg) {
        case PPC_MSG_CALL_FUNCTION:
                generic_smp_call_function_interrupt();
                break;
        case PPC_MSG_RESCHEDULE:
                /* we notice need_resched on exit */
                break;
        case PPC_MSG_CALL_FUNC_SINGLE:
                generic_smp_call_function_single_interrupt();
                break;
        case PPC_MSG_DEBUGGER_BREAK:
                if (crash_ipi_function_ptr) {
                        crash_ipi_function_ptr(get_irq_regs());
                        break;
                }
#ifdef CONFIG_DEBUGGER
                debugger_ipi(get_irq_regs());
                break;
#endif /* CONFIG_DEBUGGER */
                /* FALLTHROUGH */
        default:
                printk("SMP %d: smp_message_recv(): unknown msg %d\n",
                       smp_processor_id(), msg);
                break;
        }
}

static irqreturn_t call_function_action(int irq, void *data)
{
        generic_smp_call_function_interrupt();
        return IRQ_HANDLED;
}

static irqreturn_t reschedule_action(int irq, void *data)
{
        /* we just need the return path side effect of checking need_resched */
        return IRQ_HANDLED;
}

static irqreturn_t call_function_single_action(int irq, void *data)
{
        generic_smp_call_function_single_interrupt();
        return IRQ_HANDLED;
}

static irqreturn_t debug_ipi_action(int irq, void *data)
{
        smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
        return IRQ_HANDLED;
}

static irq_handler_t smp_ipi_action[] = {
        [PPC_MSG_CALL_FUNCTION] =  call_function_action,
        [PPC_MSG_RESCHEDULE] = reschedule_action,
        [PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
        [PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
};

const char *smp_ipi_name[] = {
        [PPC_MSG_CALL_FUNCTION] =  "ipi call function",
        [PPC_MSG_RESCHEDULE] = "ipi reschedule",
        [PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
        [PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
};

/* optional function to request ipi, for controllers with >= 4 ipis */
int smp_request_message_ipi(int virq, int msg)
{
        int err;

        if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
                return -EINVAL;
        }
#if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
        if (msg == PPC_MSG_DEBUGGER_BREAK) {
                return 1;
        }
#endif
        err = request_irq(virq, smp_ipi_action[msg], IRQF_DISABLED|IRQF_PERCPU,
                          smp_ipi_name[msg], 0);
        WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
                virq, smp_ipi_name[msg], err);

        return err;
}

void smp_send_reschedule(int cpu)
{
        if (likely(smp_ops))
                smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
}

void arch_send_call_function_single_ipi(int cpu)
{
        smp_ops->message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
        unsigned int cpu;

        for_each_cpu(cpu, mask)
                smp_ops->message_pass(cpu, PPC_MSG_CALL_FUNCTION);
}

#ifdef CONFIG_DEBUGGER
void smp_send_debugger_break(int cpu)
{
        if (likely(smp_ops))
                smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
}
#endif

#ifdef CONFIG_KEXEC
void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
{
        crash_ipi_function_ptr = crash_ipi_callback;
        if (crash_ipi_callback && smp_ops) {
                mb();
                smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_DEBUGGER_BREAK);
        }
}
#endif

static void stop_this_cpu(void *dummy)
{
        local_irq_disable();
        while (1)
                ;
}

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

struct thread_info *current_set[NR_CPUS];

static void __devinit smp_store_cpu_info(int id)
{
        per_cpu(pvr, id) = mfspr(SPRN_PVR);
}

static void __init smp_create_idle(unsigned int cpu)
{
        struct task_struct *p;

        /* create a process for the processor */
        p = fork_idle(cpu);
        if (IS_ERR(p))
                panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
#ifdef CONFIG_PPC64
        paca[cpu].__current = p;
        paca[cpu].kstack = (unsigned long) task_thread_info(p)
                + THREAD_SIZE - STACK_FRAME_OVERHEAD;
#endif
        current_set[cpu] = task_thread_info(p);
        task_thread_info(p)->cpu = cpu;
}

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

        DBG("smp_prepare_cpus\n");

        /* 
         * setup_cpu may need to be called on the boot cpu. We havent
         * spun any cpus up but lets be paranoid.
         */
        BUG_ON(boot_cpuid != smp_processor_id());

        /* Fixup boot cpu */
        smp_store_cpu_info(boot_cpuid);
        cpu_callin_map[boot_cpuid] = 1;

        if (smp_ops)
                if (smp_ops->probe)
                        max_cpus = smp_ops->probe();
                else
                        max_cpus = NR_CPUS;
        else
                max_cpus = 1;
 
        smp_space_timers(max_cpus);

        for_each_possible_cpu(cpu)
                if (cpu != boot_cpuid)
                        smp_create_idle(cpu);
}

void __devinit smp_prepare_boot_cpu(void)
{
        BUG_ON(smp_processor_id() != boot_cpuid);

        set_cpu_online(boot_cpuid, true);
        cpu_set(boot_cpuid, per_cpu(cpu_sibling_map, boot_cpuid));
        cpu_set(boot_cpuid, per_cpu(cpu_core_map, boot_cpuid));
#ifdef CONFIG_PPC64
        paca[boot_cpuid].__current = current;
#endif
        current_set[boot_cpuid] = task_thread_info(current);
}

#ifdef CONFIG_HOTPLUG_CPU
/* State of each CPU during hotplug phases */
DEFINE_PER_CPU(int, cpu_state) = { 0 };

int generic_cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();

        if (cpu == boot_cpuid)
                return -EBUSY;

        set_cpu_online(cpu, false);
#ifdef CONFIG_PPC64
        vdso_data->processorCount--;
        fixup_irqs(cpu_online_map);
#endif
        return 0;
}

int generic_cpu_enable(unsigned int cpu)
{
        /* Do the normal bootup if we haven't
         * already bootstrapped. */
        if (system_state != SYSTEM_RUNNING)
                return -ENOSYS;

        /* get the target out of it's holding state */
        per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
        smp_wmb();

        while (!cpu_online(cpu))
                cpu_relax();

#ifdef CONFIG_PPC64
        fixup_irqs(cpu_online_map);
        /* counter the irq disable in fixup_irqs */
        local_irq_enable();
#endif
        return 0;
}

void generic_cpu_die(unsigned int cpu)
{
        int i;

        for (i = 0; i < 100; i++) {
                smp_rmb();
                if (per_cpu(cpu_state, cpu) == CPU_DEAD)
                        return;
                msleep(100);
        }
        printk(KERN_ERR "CPU%d didn't die...\n", cpu);
}

void generic_mach_cpu_die(void)
{
        unsigned int cpu;

        local_irq_disable();
        cpu = smp_processor_id();
        printk(KERN_DEBUG "CPU%d offline\n", cpu);
        __get_cpu_var(cpu_state) = CPU_DEAD;
        smp_wmb();
        while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
                cpu_relax();
        set_cpu_online(cpu, true);
        local_irq_enable();
}
#endif

static int __devinit cpu_enable(unsigned int cpu)
{
        if (smp_ops && smp_ops->cpu_enable)
                return smp_ops->cpu_enable(cpu);

        return -ENOSYS;
}

int __cpuinit __cpu_up(unsigned int cpu)
{
        int c;

        secondary_ti = current_set[cpu];
        if (!cpu_enable(cpu))
                return 0;

        if (smp_ops == NULL ||
            (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
                return -EINVAL;

        /* Make sure callin-map entry is 0 (can be leftover a CPU
         * hotplug
         */
        cpu_callin_map[cpu] = 0;

        /* The information for processor bringup must
         * be written out to main store before we release
         * the processor.
         */
        smp_mb();

        /* wake up cpus */
        DBG("smp: kicking cpu %d\n", cpu);
        smp_ops->kick_cpu(cpu);

        /*
         * wait to see if the cpu made a callin (is actually up).
         * use this value that I found through experimentation.
         * -- Cort
         */
        if (system_state < SYSTEM_RUNNING)
                for (c = 50000; c && !cpu_callin_map[cpu]; c--)
                        udelay(100);
#ifdef CONFIG_HOTPLUG_CPU
        else
                /*
                 * CPUs can take much longer to come up in the
                 * hotplug case.  Wait five seconds.
                 */
                for (c = 5000; c && !cpu_callin_map[cpu]; c--)
                        msleep(1);
#endif

        if (!cpu_callin_map[cpu]) {
                printk("Processor %u is stuck.\n", cpu);
                return -ENOENT;
        }

        printk("Processor %u found.\n", cpu);

        if (smp_ops->give_timebase)
                smp_ops->give_timebase();

        /* Wait until cpu puts itself in the online map */
        while (!cpu_online(cpu))
                cpu_relax();

        return 0;
}

/* Return the value of the reg property corresponding to the given
 * logical cpu.
 */
int cpu_to_core_id(int cpu)
{
        struct device_node *np;
        const int *reg;
        int id = -1;

        np = of_get_cpu_node(cpu, NULL);
        if (!np)
                goto out;

        reg = of_get_property(np, "reg", NULL);
        if (!reg)
                goto out;

        id = *reg;
out:
        of_node_put(np);
        return id;
}

/* Must be called when no change can occur to cpu_present_map,
 * i.e. during cpu online or offline.
 */
static struct device_node *cpu_to_l2cache(int cpu)
{
        struct device_node *np;
        struct device_node *cache;

        if (!cpu_present(cpu))
                return NULL;

        np = of_get_cpu_node(cpu, NULL);
        if (np == NULL)
                return NULL;

        cache = of_find_next_cache_node(np);

        of_node_put(np);

        return cache;
}

/* Activate a secondary processor. */
int __devinit start_secondary(void *unused)
{
        unsigned int cpu = smp_processor_id();
        struct device_node *l2_cache;
        int i, base;

        atomic_inc(&init_mm.mm_count);
        current->active_mm = &init_mm;

        smp_store_cpu_info(cpu);
        set_dec(tb_ticks_per_jiffy);
        preempt_disable();
        cpu_callin_map[cpu] = 1;

        if (smp_ops->setup_cpu)
                smp_ops->setup_cpu(cpu);
        if (smp_ops->take_timebase)
                smp_ops->take_timebase();

        if (system_state > SYSTEM_BOOTING)
                snapshot_timebase();

        secondary_cpu_time_init();

        ipi_call_lock();
        notify_cpu_starting(cpu);
        set_cpu_online(cpu, true);
        /* Update sibling maps */
        base = cpu_first_thread_in_core(cpu);
        for (i = 0; i < threads_per_core; i++) {
                if (cpu_is_offline(base + i))
                        continue;
                cpu_set(cpu, per_cpu(cpu_sibling_map, base + i));
                cpu_set(base + i, per_cpu(cpu_sibling_map, cpu));

                /* cpu_core_map should be a superset of
                 * cpu_sibling_map even if we don't have cache
                 * information, so update the former here, too.
                 */
                cpu_set(cpu, per_cpu(cpu_core_map, base +i));
                cpu_set(base + i, per_cpu(cpu_core_map, cpu));
        }
        l2_cache = cpu_to_l2cache(cpu);
        for_each_online_cpu(i) {
                struct device_node *np = cpu_to_l2cache(i);
                if (!np)
                        continue;
                if (np == l2_cache) {
                        cpu_set(cpu, per_cpu(cpu_core_map, i));
                        cpu_set(i, per_cpu(cpu_core_map, cpu));
                }
                of_node_put(np);
        }
        of_node_put(l2_cache);
        ipi_call_unlock();

        local_irq_enable();

        cpu_idle();
        return 0;
}

int setup_profiling_timer(unsigned int multiplier)
{
        return 0;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
        cpumask_t old_mask;

        /* We want the setup_cpu() here to be called from CPU 0, but our
         * init thread may have been "borrowed" by another CPU in the meantime
         * se we pin us down to CPU 0 for a short while
         */
        old_mask = current->cpus_allowed;
        set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));
        
        if (smp_ops && smp_ops->setup_cpu)
                smp_ops->setup_cpu(boot_cpuid);

        set_cpus_allowed(current, old_mask);

        snapshot_timebases();

        dump_numa_cpu_topology();
}

#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
        struct device_node *l2_cache;
        int cpu = smp_processor_id();
        int base, i;
        int err;

        if (!smp_ops->cpu_disable)
                return -ENOSYS;

        err = smp_ops->cpu_disable();
        if (err)
                return err;

        /* Update sibling maps */
        base = cpu_first_thread_in_core(cpu);
        for (i = 0; i < threads_per_core; i++) {
                cpu_clear(cpu, per_cpu(cpu_sibling_map, base + i));
                cpu_clear(base + i, per_cpu(cpu_sibling_map, cpu));
                cpu_clear(cpu, per_cpu(cpu_core_map, base +i));
                cpu_clear(base + i, per_cpu(cpu_core_map, cpu));
        }

        l2_cache = cpu_to_l2cache(cpu);
        for_each_present_cpu(i) {
                struct device_node *np = cpu_to_l2cache(i);
                if (!np)
                        continue;
                if (np == l2_cache) {
                        cpu_clear(cpu, per_cpu(cpu_core_map, i));
                        cpu_clear(i, per_cpu(cpu_core_map, cpu));
                }
                of_node_put(np);
        }
        of_node_put(l2_cache);


        return 0;
}

void __cpu_die(unsigned int cpu)
{
        if (smp_ops->cpu_die)
                smp_ops->cpu_die(cpu);
}
#endif