ARM: SMP: wait for CPU to be marked active

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / arm / kernel / smp.c

/*
 *  linux/arch/arm/kernel/smp.c
 *
 *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/ftrace.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/localtimer.h>

/*
 * as from 2.5, kernels no longer have an init_tasks structure
 * so we need some other way of telling a new secondary core
 * where to place its SVC stack
 */
struct secondary_data secondary_data;

enum ipi_msg_type {
        IPI_TIMER = 2,
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CALL_FUNC_SINGLE,
        IPI_CPU_STOP,
};

int __cpuinit __cpu_up(unsigned int cpu)
{
        struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
        struct task_struct *idle = ci->idle;
        pgd_t *pgd;
        int ret;

        /*
         * Spawn a new process manually, if not already done.
         * Grab a pointer to its task struct so we can mess with it
         */
        if (!idle) {
                idle = fork_idle(cpu);
                if (IS_ERR(idle)) {
                        printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
                        return PTR_ERR(idle);
                }
                ci->idle = idle;
        } else {
                /*
                 * Since this idle thread is being re-used, call
                 * init_idle() to reinitialize the thread structure.
                 */
                init_idle(idle, cpu);
        }

        /*
         * Allocate initial page tables to allow the new CPU to
         * enable the MMU safely.  This essentially means a set
         * of our "standard" page tables, with the addition of
         * a 1:1 mapping for the physical address of the kernel.
         */
        pgd = pgd_alloc(&init_mm);
        if (!pgd)
                return -ENOMEM;

        if (PHYS_OFFSET != PAGE_OFFSET) {
#ifndef CONFIG_HOTPLUG_CPU
                identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end));
#endif
                identity_mapping_add(pgd, __pa(_stext), __pa(_etext));
                identity_mapping_add(pgd, __pa(_sdata), __pa(_edata));
        }

        /*
         * We need to tell the secondary core where to find
         * its stack and the page tables.
         */
        secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
        secondary_data.pgdir = virt_to_phys(pgd);
        secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
        __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
        outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));

        /*
         * Now bring the CPU into our world.
         */
        ret = boot_secondary(cpu, idle);
        if (ret == 0) {
                unsigned long timeout;

                /*
                 * CPU was successfully started, wait for it
                 * to come online or time out.
                 */
                timeout = jiffies + HZ;
                while (time_before(jiffies, timeout)) {
                        if (cpu_online(cpu))
                                break;

                        udelay(10);
                        barrier();
                }

                if (!cpu_online(cpu)) {
                        pr_crit("CPU%u: failed to come online\n", cpu);
                        ret = -EIO;
                }
        } else {
                pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
        }

        secondary_data.stack = NULL;
        secondary_data.pgdir = 0;

        if (PHYS_OFFSET != PAGE_OFFSET) {
#ifndef CONFIG_HOTPLUG_CPU
                identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end));
#endif
                identity_mapping_del(pgd, __pa(_stext), __pa(_etext));
                identity_mapping_del(pgd, __pa(_sdata), __pa(_edata));
        }

        pgd_free(&init_mm, pgd);

        return ret;
}

#ifdef CONFIG_HOTPLUG_CPU
static void percpu_timer_stop(void);

/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();
        struct task_struct *p;
        int ret;

        ret = platform_cpu_disable(cpu);
        if (ret)
                return ret;

        /*
         * Take this CPU offline.  Once we clear this, we can't return,
         * and we must not schedule until we're ready to give up the cpu.
         */
        set_cpu_online(cpu, false);

        /*
         * OK - migrate IRQs away from this CPU
         */
        migrate_irqs();

        /*
         * Stop the local timer for this CPU.
         */
        percpu_timer_stop();

        /*
         * Flush user cache and TLB mappings, and then remove this CPU
         * from the vm mask set of all processes.
         */
        flush_cache_all();
        local_flush_tlb_all();

        read_lock(&tasklist_lock);
        for_each_process(p) {
                if (p->mm)
                        cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
        }
        read_unlock(&tasklist_lock);

        return 0;
}

static DECLARE_COMPLETION(cpu_died);

/*
 * called on the thread which is asking for a CPU to be shutdown -
 * waits until shutdown has completed, or it is timed out.
 */
void __cpu_die(unsigned int cpu)
{
        if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
                pr_err("CPU%u: cpu didn't die\n", cpu);
                return;
        }
        printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);

        if (!platform_cpu_kill(cpu))
                printk("CPU%u: unable to kill\n", cpu);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 *
 * Note that we disable IRQs here, but do not re-enable them
 * before returning to the caller. This is also the behaviour
 * of the other hotplug-cpu capable cores, so presumably coming
 * out of idle fixes this.
 */
void __ref cpu_die(void)
{
        unsigned int cpu = smp_processor_id();

        idle_task_exit();

        local_irq_disable();
        mb();

        /* Tell __cpu_die() that this CPU is now safe to dispose of */
        complete(&cpu_died);

        /*
         * actual CPU shutdown procedure is at least platform (if not
         * CPU) specific.
         */
        platform_cpu_die(cpu);

        /*
         * Do not return to the idle loop - jump back to the secondary
         * cpu initialisation.  There's some initialisation which needs
         * to be repeated to undo the effects of taking the CPU offline.
         */
        __asm__("mov    sp, %0\n"
        "       mov     fp, #0\n"
        "       b       secondary_start_kernel"
                :
                : "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */

/*
 * Called by both boot and secondaries to move global data into
 * per-processor storage.
 */
static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
{
        struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

        cpu_info->loops_per_jiffy = loops_per_jiffy;
}

/*
 * This is the secondary CPU boot entry.  We're using this CPUs
 * idle thread stack, but a set of temporary page tables.
 */
asmlinkage void __cpuinit secondary_start_kernel(void)
{
        struct mm_struct *mm = &init_mm;
        unsigned int cpu = smp_processor_id();

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

        /*
         * 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));
        cpu_switch_mm(mm->pgd, mm);
        enter_lazy_tlb(mm, current);
        local_flush_tlb_all();

        cpu_init();
        preempt_disable();
        trace_hardirqs_off();

        /*
         * Give the platform a chance to do its own initialisation.
         */
        platform_secondary_init(cpu);

        /*
         * Enable local interrupts.
         */
        notify_cpu_starting(cpu);
        local_irq_enable();
        local_fiq_enable();

        /*
         * Setup the percpu timer for this CPU.
         */
        percpu_timer_setup();

        calibrate_delay();

        smp_store_cpu_info(cpu);

        /*
         * OK, now it's safe to let the boot CPU continue.  Wait for
         * the CPU migration code to notice that the CPU is online
         * before we continue.
         */
        set_cpu_online(cpu, true);
        while (!cpu_active(cpu))
                cpu_relax();

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

void __init smp_cpus_done(unsigned int max_cpus)
{
        int cpu;
        unsigned long bogosum = 0;

        for_each_online_cpu(cpu)
                bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;

        printk(KERN_INFO "SMP: Total of %d processors activated "
               "(%lu.%02lu BogoMIPS).\n",
               num_online_cpus(),
               bogosum / (500000/HZ),
               (bogosum / (5000/HZ)) % 100);
}

void __init smp_prepare_boot_cpu(void)
{
        unsigned int cpu = smp_processor_id();

        per_cpu(cpu_data, cpu).idle = current;
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        unsigned int ncores = num_possible_cpus();

        smp_store_cpu_info(smp_processor_id());

        /*
         * are we trying to boot more cores than exist?
         */
        if (max_cpus > ncores)
                max_cpus = ncores;

        if (max_cpus > 1) {
                /*
                 * Enable the local timer or broadcast device for the
                 * boot CPU, but only if we have more than one CPU.
                 */
                percpu_timer_setup();

                /*
                 * Initialise the SCU if there are more than one CPU
                 * and let them know where to start.
                 */
                platform_smp_prepare_cpus(max_cpus);
        }
}

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

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

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

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

static const char *ipi_types[NR_IPI] = {
#define S(x,s)  [x - IPI_TIMER] = s
        S(IPI_TIMER, "Timer broadcast interrupts"),
        S(IPI_RESCHEDULE, "Rescheduling interrupts"),
        S(IPI_CALL_FUNC, "Function call interrupts"),
        S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
        S(IPI_CPU_STOP, "CPU stop interrupts"),
};

void show_ipi_list(struct seq_file *p, int prec)
{
        unsigned int cpu, i;

        for (i = 0; i < NR_IPI; i++) {
                seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);

                for_each_present_cpu(cpu)
                        seq_printf(p, "%10u ",
                                   __get_irq_stat(cpu, ipi_irqs[i]));

                seq_printf(p, " %s\n", ipi_types[i]);
        }
}

u64 smp_irq_stat_cpu(unsigned int cpu)
{
        u64 sum = 0;
        int i;

        for (i = 0; i < NR_IPI; i++)
                sum += __get_irq_stat(cpu, ipi_irqs[i]);

#ifdef CONFIG_LOCAL_TIMERS
        sum += __get_irq_stat(cpu, local_timer_irqs);
#endif

        return sum;
}

/*
 * Timer (local or broadcast) support
 */
static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);

static void ipi_timer(void)
{
        struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
        irq_enter();
        evt->event_handler(evt);
        irq_exit();
}

#ifdef CONFIG_LOCAL_TIMERS
asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);
        int cpu = smp_processor_id();

        if (local_timer_ack()) {
                __inc_irq_stat(cpu, local_timer_irqs);
                ipi_timer();
        }

        set_irq_regs(old_regs);
}

void show_local_irqs(struct seq_file *p, int prec)
{
        unsigned int cpu;

        seq_printf(p, "%*s: ", prec, "LOC");

        for_each_present_cpu(cpu)
                seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));

        seq_printf(p, " Local timer interrupts\n");
}
#endif

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static void smp_timer_broadcast(const struct cpumask *mask)
{
        smp_cross_call(mask, IPI_TIMER);
}
#else
#define smp_timer_broadcast     NULL
#endif

static void broadcast_timer_set_mode(enum clock_event_mode mode,
        struct clock_event_device *evt)
{
}

static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
{
        evt->name       = "dummy_timer";
        evt->features   = CLOCK_EVT_FEAT_ONESHOT |
                          CLOCK_EVT_FEAT_PERIODIC |
                          CLOCK_EVT_FEAT_DUMMY;
        evt->rating     = 400;
        evt->mult       = 1;
        evt->set_mode   = broadcast_timer_set_mode;

        clockevents_register_device(evt);
}

void __cpuinit percpu_timer_setup(void)
{
        unsigned int cpu = smp_processor_id();
        struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);

        evt->cpumask = cpumask_of(cpu);
        evt->broadcast = smp_timer_broadcast;

        if (local_timer_setup(evt))
                broadcast_timer_setup(evt);
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * The generic clock events code purposely does not stop the local timer
 * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
 * manually here.
 */
static void percpu_timer_stop(void)
{
        unsigned int cpu = smp_processor_id();
        struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);

        evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
}
#endif

static DEFINE_SPINLOCK(stop_lock);

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
        if (system_state == SYSTEM_BOOTING ||
            system_state == SYSTEM_RUNNING) {
                spin_lock(&stop_lock);
                printk(KERN_CRIT "CPU%u: stopping\n", cpu);
                dump_stack();
                spin_unlock(&stop_lock);
        }

        set_cpu_online(cpu, false);

        local_fiq_disable();
        local_irq_disable();

        while (1)
                cpu_relax();
}

/*
 * Main handler for inter-processor interrupts
 */
asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
{
        unsigned int cpu = smp_processor_id();
        struct pt_regs *old_regs = set_irq_regs(regs);

        if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI)
                __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]);

        switch (ipinr) {
        case IPI_TIMER:
                ipi_timer();
                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;

        case IPI_CPU_STOP:
                ipi_cpu_stop(cpu);
                break;

        default:
                printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
                       cpu, ipinr);
                break;
        }
        set_irq_regs(old_regs);
}

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

void smp_send_stop(void)
{
        unsigned long timeout;

        if (num_online_cpus() > 1) {
                cpumask_t mask = cpu_online_map;
                cpu_clear(smp_processor_id(), mask);

                smp_cross_call(&mask, IPI_CPU_STOP);
        }

        /* Wait up to one second for other CPUs to stop */
        timeout = USEC_PER_SEC;
        while (num_online_cpus() > 1 && timeout--)
                udelay(1);

        if (num_online_cpus() > 1)
                pr_warning("SMP: failed to stop secondary CPUs\n");
}

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