Linux-2.6.12-rc2

[mirror_ubuntu-artful-kernel.git] / arch / ppc64 / kernel / smp.c

/*
 * 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/config.h>
#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 <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/paca.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/system.h>
#include <asm/abs_addr.h>

#include "mpic.h"

#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

cpumask_t cpu_possible_map = CPU_MASK_NONE;
cpumask_t cpu_online_map = CPU_MASK_NONE;
cpumask_t cpu_sibling_map[NR_CPUS] = { [0 ... NR_CPUS-1] = CPU_MASK_NONE };

EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);

struct smp_ops_t *smp_ops;

static volatile unsigned int cpu_callin_map[NR_CPUS];

extern unsigned char stab_array[];

void smp_call_function_interrupt(void);

int smt_enabled_at_boot = 1;

#ifdef CONFIG_PPC_MULTIPLATFORM
void smp_mpic_message_pass(int target, int msg)
{
        /* make sure we're sending something that translates to an IPI */
        if ( msg > 0x3 ){
                printk("SMP %d: smp_message_pass: unknown msg %d\n",
                       smp_processor_id(), msg);
                return;
        }
        switch ( target )
        {
        case MSG_ALL:
                mpic_send_ipi(msg, 0xffffffff);
                break;
        case MSG_ALL_BUT_SELF:
                mpic_send_ipi(msg, 0xffffffff & ~(1 << smp_processor_id()));
                break;
        default:
                mpic_send_ipi(msg, 1 << target);
                break;
        }
}

int __init smp_mpic_probe(void)
{
        int nr_cpus;

        DBG("smp_mpic_probe()...\n");

        nr_cpus = cpus_weight(cpu_possible_map);

        DBG("nr_cpus: %d\n", nr_cpus);

        if (nr_cpus > 1)
                mpic_request_ipis();

        return nr_cpus;
}

void __devinit smp_mpic_setup_cpu(int cpu)
{
        mpic_setup_this_cpu();
}

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;
        mb();
}

#endif /* CONFIG_PPC_MULTIPLATFORM */

static void __init smp_space_timers(unsigned int max_cpus)
{
        int i;
        unsigned long offset = tb_ticks_per_jiffy / max_cpus;
        unsigned long previous_tb = paca[boot_cpuid].next_jiffy_update_tb;

        for_each_cpu(i) {
                if (i != boot_cpuid) {
                        paca[i].next_jiffy_update_tb =
                                previous_tb + offset;
                        previous_tb = paca[i].next_jiffy_update_tb;
                }
        }
}

void smp_message_recv(int msg, struct pt_regs *regs)
{
        switch(msg) {
        case PPC_MSG_CALL_FUNCTION:
                smp_call_function_interrupt();
                break;
        case PPC_MSG_RESCHEDULE: 
                /* XXX Do we have to do this? */
                set_need_resched();
                break;
#if 0
        case PPC_MSG_MIGRATE_TASK:
                /* spare */
                break;
#endif
#ifdef CONFIG_DEBUGGER
        case PPC_MSG_DEBUGGER_BREAK:
                debugger_ipi(regs);
                break;
#endif
        default:
                printk("SMP %d: smp_message_recv(): unknown msg %d\n",
                       smp_processor_id(), msg);
                break;
        }
}

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

#ifdef CONFIG_DEBUGGER
void smp_send_debugger_break(int cpu)
{
        smp_ops->message_pass(cpu, 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, 1, 0);
}

/*
 * Structure and data for smp_call_function(). This is designed to minimise
 * static memory requirements. It also looks cleaner.
 * Stolen from the i386 version.
 */
static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_lock);

static struct call_data_struct {
        void (*func) (void *info);
        void *info;
        atomic_t started;
        atomic_t finished;
        int wait;
} *call_data;

/* delay of at least 8 seconds on 1GHz cpu */
#define SMP_CALL_TIMEOUT (1UL << (30 + 3))

/*
 * This function sends a 'generic call function' IPI to all other CPUs
 * in the system.
 *
 * [SUMMARY] Run a function on all other CPUs.
 * <func> The function to run. This must be fast and non-blocking.
 * <info> An arbitrary pointer to pass to the function.
 * <nonatomic> currently unused.
 * <wait> If true, wait (atomically) until function has completed on other CPUs.
 * [RETURNS] 0 on success, else a negative status code. Does not return until
 * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
                       int wait)
{ 
        struct call_data_struct data;
        int ret = -1, cpus;
        unsigned long timeout;

        /* Can deadlock when called with interrupts disabled */
        WARN_ON(irqs_disabled());

        data.func = func;
        data.info = info;
        atomic_set(&data.started, 0);
        data.wait = wait;
        if (wait)
                atomic_set(&data.finished, 0);

        spin_lock(&call_lock);
        /* Must grab online cpu count with preempt disabled, otherwise
         * it can change. */
        cpus = num_online_cpus() - 1;
        if (!cpus) {
                ret = 0;
                goto out;
        }

        call_data = &data;
        wmb();
        /* Send a message to all other CPUs and wait for them to respond */
        smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION);

        /* Wait for response */
        timeout = SMP_CALL_TIMEOUT;
        while (atomic_read(&data.started) != cpus) {
                HMT_low();
                if (--timeout == 0) {
                        printk("smp_call_function on cpu %d: other cpus not "
                               "responding (%d)\n", smp_processor_id(),
                               atomic_read(&data.started));
                        debugger(NULL);
                        goto out;
                }
        }

        if (wait) {
                timeout = SMP_CALL_TIMEOUT;
                while (atomic_read(&data.finished) != cpus) {
                        HMT_low();
                        if (--timeout == 0) {
                                printk("smp_call_function on cpu %d: other "
                                       "cpus not finishing (%d/%d)\n",
                                       smp_processor_id(),
                                       atomic_read(&data.finished),
                                       atomic_read(&data.started));
                                debugger(NULL);
                                goto out;
                        }
                }
        }

        ret = 0;

out:
        call_data = NULL;
        HMT_medium();
        spin_unlock(&call_lock);
        return ret;
}

EXPORT_SYMBOL(smp_call_function);

void smp_call_function_interrupt(void)
{
        void (*func) (void *info);
        void *info;
        int wait;

        /* call_data will be NULL if the sender timed out while
         * waiting on us to receive the call.
         */
        if (!call_data)
                return;

        func = call_data->func;
        info = call_data->info;
        wait = call_data->wait;

        if (!wait)
                smp_mb__before_atomic_inc();

        /*
         * Notify initiating CPU that I've grabbed the data and am
         * about to execute the function
         */
        atomic_inc(&call_data->started);
        /*
         * At this point the info structure may be out of scope unless wait==1
         */
        (*func)(info);
        if (wait) {
                smp_mb__before_atomic_inc();
                atomic_inc(&call_data->finished);
        }
}

extern unsigned long decr_overclock;
extern struct gettimeofday_struct do_gtod;

struct thread_info *current_set[NR_CPUS];

DECLARE_PER_CPU(unsigned int, pvr);

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));
        paca[cpu].__current = p;
        current_set[cpu] = p->thread_info;
}

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;

#ifndef CONFIG_PPC_ISERIES
        paca[boot_cpuid].next_jiffy_update_tb = tb_last_stamp = get_tb();

        /*
         * Should update do_gtod.stamp_xsec.
         * For now we leave it which means the time can be some
         * number of msecs off until someone does a settimeofday()
         */
        do_gtod.varp->tb_orig_stamp = tb_last_stamp;
        systemcfg->tb_orig_stamp = tb_last_stamp;
#endif

        max_cpus = smp_ops->probe();
 
        smp_space_timers(max_cpus);

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

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

        cpu_set(boot_cpuid, cpu_online_map);

        paca[boot_cpuid].__current = current;
        current_set[boot_cpuid] = current->thread_info;
}

#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;

        systemcfg->processorCount--;
        cpu_clear(cpu, cpu_online_map);
        fixup_irqs(cpu_online_map);
        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;
        wmb();

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

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

void generic_cpu_die(unsigned int cpu)
{
        int i;

        for (i = 0; i < 100; i++) {
                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;
        wmb();
        while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
                cpu_relax();

        flush_tlb_pending();
        cpu_set(cpu, cpu_online_map);
        local_irq_enable();
}
#endif

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

        return -ENOSYS;
}

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

        if (!cpu_enable(cpu))
                return 0;

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

        paca[cpu].default_decr = tb_ticks_per_jiffy / decr_overclock;

        if (!cpu_has_feature(CPU_FTR_SLB)) {
                void *tmp;

                /* maximum of 48 CPUs on machines with a segment table */
                if (cpu >= 48)
                        BUG();

                tmp = &stab_array[PAGE_SIZE * cpu];
                memset(tmp, 0, PAGE_SIZE); 
                paca[cpu].stab_addr = (unsigned long)tmp;
                paca[cpu].stab_real = virt_to_abs(tmp);
        }

        /* 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.
         */
        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 = 5000; 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 = 25; c && !cpu_callin_map[cpu]; c--) {
                        msleep(200);
                }
#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;
}


/* Activate a secondary processor. */
int __devinit start_secondary(void *unused)
{
        unsigned int cpu = smp_processor_id();

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

        smp_store_cpu_info(cpu);
        set_dec(paca[cpu].default_decr);
        cpu_callin_map[cpu] = 1;

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

        spin_lock(&call_lock);
        cpu_set(cpu, cpu_online_map);
        spin_unlock(&call_lock);

        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));
        
        smp_ops->setup_cpu(boot_cpuid);

        set_cpus_allowed(current, old_mask);
}

#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
        if (smp_ops->cpu_disable)
                return smp_ops->cpu_disable();

        return -ENOSYS;
}

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