smp.c

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/*
 * IPI management based on arch/arm/kernel/smp.c (Copyright 2002 ARM Limited)
 *
 * Copyright 2007-2009 Analog Devices Inc.
 *                         Philippe Gerum <[email protected]>
 *
 * Licensed under the GPL-2.
 */

#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/clockchips.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/irq_handler.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <linux/err.h>

/*
 * Anomaly notes:
 * 05000120 - we always define corelock as 32-bit integer in L2
 */
struct corelock_slot corelock __attribute__ ((__section__(".l2.bss")));

#ifdef CONFIG_ICACHE_FLUSH_L1
unsigned long blackfin_iflush_l1_entry[NR_CPUS];
#endif

struct blackfin_initial_pda __cpuinitdata initial_pda_coreb;

enum ipi_message_type {
    BFIN_IPI_TIMER,
    BFIN_IPI_RESCHEDULE,
    BFIN_IPI_CALL_FUNC,
    BFIN_IPI_CALL_FUNC_SINGLE,
    BFIN_IPI_CPU_STOP,
};

struct blackfin_flush_data {
    unsigned long start;
    unsigned long end;
};

void *secondary_stack;

static struct blackfin_flush_data smp_flush_data;

static DEFINE_SPINLOCK(stop_lock);

/* A magic number - stress test shows this is safe for common cases */
#define BFIN_IPI_MSGQ_LEN 5

/* Simple FIFO buffer, overflow leads to panic */
struct ipi_data {
    unsigned long count;
    unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, bfin_ipi);

static void ipi_cpu_stop(unsigned int cpu)
{
    spin_lock(&stop_lock);
    printk(KERN_CRIT "CPU%u: stopping\n", cpu);
    dump_stack();
    spin_unlock(&stop_lock);

    set_cpu_online(cpu, false);

    local_irq_disable();

    while (1)
        SSYNC();
}

static void ipi_flush_icache(void *info)
{
    struct blackfin_flush_data *fdata = info;

    /* Invalidate the memory holding the bounds of the flushed region. */
    blackfin_dcache_invalidate_range((unsigned long)fdata,
                     (unsigned long)fdata + sizeof(*fdata));

    /* Make sure all write buffers in the data side of the core
     * are flushed before trying to invalidate the icache.  This
     * needs to be after the data flush and before the icache
     * flush so that the SSYNC does the right thing in preventing
     * the instruction prefetcher from hitting things in cached
     * memory at the wrong time -- it runs much further ahead than
     * the pipeline.
     */
    SSYNC();

    /* ipi_flaush_icache is invoked by generic flush_icache_range,
     * so call blackfin arch icache flush directly here.
     */
    blackfin_icache_flush_range(fdata->start, fdata->end);
}

/* Use IRQ_SUPPLE_0 to request reschedule.
 * When returning from interrupt to user space,
 * there is chance to reschedule */
static irqreturn_t ipi_handler_int0(int irq, void *dev_instance)
{
    unsigned int cpu = smp_processor_id();

    platform_clear_ipi(cpu, IRQ_SUPPLE_0);
    return IRQ_HANDLED;
}

DECLARE_PER_CPU(struct clock_event_device, coretmr_events);
void ipi_timer(void)
{
    int cpu = smp_processor_id();
    struct clock_event_device *evt = &per_cpu(coretmr_events, cpu);
    evt->event_handler(evt);
}

static irqreturn_t ipi_handler_int1(int irq, void *dev_instance)
{
    struct ipi_data *bfin_ipi_data;
    unsigned int cpu = smp_processor_id();
    unsigned long pending;
    unsigned long msg;

    platform_clear_ipi(cpu, IRQ_SUPPLE_1);

    bfin_ipi_data = &__get_cpu_var(bfin_ipi);
    smp_mb();
    while ((pending = xchg(&bfin_ipi_data->bits, 0)) != 0) {
        msg = 0;
        do {
            msg = find_next_bit(&pending, BITS_PER_LONG, msg + 1);
            switch (msg) {
            case BFIN_IPI_TIMER:
                ipi_timer();
                break;
            case BFIN_IPI_RESCHEDULE:
                scheduler_ipi();
                break;
            case BFIN_IPI_CALL_FUNC:
                generic_smp_call_function_interrupt();
                break;

            case BFIN_IPI_CALL_FUNC_SINGLE:
                generic_smp_call_function_single_interrupt();
                break;

            case BFIN_IPI_CPU_STOP:
                ipi_cpu_stop(cpu);
                break;
            }
        } while (msg < BITS_PER_LONG);

        smp_mb();
    }
    return IRQ_HANDLED;
}

static void bfin_ipi_init(void)
{
    unsigned int cpu;
    struct ipi_data *bfin_ipi_data;
    for_each_possible_cpu(cpu) {
        bfin_ipi_data = &per_cpu(bfin_ipi, cpu);
        bfin_ipi_data->bits = 0;
        bfin_ipi_data->count = 0;
    }
}

void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
{
    unsigned int cpu;
    struct ipi_data *bfin_ipi_data;
    unsigned long flags;

    local_irq_save(flags);
    smp_mb();
    for_each_cpu(cpu, cpumask) {
        bfin_ipi_data = &per_cpu(bfin_ipi, cpu);
        smp_mb();
        set_bit(msg, &bfin_ipi_data->bits);
        bfin_ipi_data->count++;
        platform_send_ipi_cpu(cpu, IRQ_SUPPLE_1);
    }

    local_irq_restore(flags);
}

void arch_send_call_function_single_ipi(int cpu)
{
    send_ipi(cpumask_of(cpu), BFIN_IPI_CALL_FUNC_SINGLE);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
    send_ipi(mask, BFIN_IPI_CALL_FUNC);
}

void smp_send_reschedule(int cpu)
{
    send_ipi(cpumask_of(cpu), BFIN_IPI_RESCHEDULE);

    return;
}

void smp_send_msg(const struct cpumask *mask, unsigned long type)
{
    send_ipi(mask, type);
}

void smp_timer_broadcast(const struct cpumask *mask)
{
    smp_send_msg(mask, BFIN_IPI_TIMER);
}

void smp_send_stop(void)
{
    cpumask_t callmap;

    preempt_disable();
    cpumask_copy(&callmap, cpu_online_mask);
    cpumask_clear_cpu(smp_processor_id(), &callmap);
    if (!cpumask_empty(&callmap))
        send_ipi(&callmap, BFIN_IPI_CPU_STOP);

    preempt_enable();

    return;
}

int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
{
    int ret;

    secondary_stack = task_stack_page(idle) + THREAD_SIZE;

    ret = platform_boot_secondary(cpu, idle);

    secondary_stack = NULL;

    return ret;
}

static void __cpuinit setup_secondary(unsigned int cpu)
{
    unsigned long ilat;

    bfin_write_IMASK(0);
    CSYNC();
    ilat = bfin_read_ILAT();
    CSYNC();
    bfin_write_ILAT(ilat);
    CSYNC();

    /* Enable interrupt levels IVG7-15. IARs have been already
     * programmed by the boot CPU.  */
    bfin_irq_flags |= IMASK_IVG15 |
        IMASK_IVG14 | IMASK_IVG13 | IMASK_IVG12 | IMASK_IVG11 |
        IMASK_IVG10 | IMASK_IVG9 | IMASK_IVG8 | IMASK_IVG7 | IMASK_IVGHW;
}

void __cpuinit secondary_start_kernel(void)
{
    unsigned int cpu = smp_processor_id();
    struct mm_struct *mm = &init_mm;

    if (_bfin_swrst & SWRST_DBL_FAULT_B) {
        printk(KERN_EMERG "CoreB Recovering from DOUBLE FAULT event\n");
#ifdef CONFIG_DEBUG_DOUBLEFAULT
        printk(KERN_EMERG " While handling exception (EXCAUSE = %#x) at %pF\n",
            initial_pda_coreb.seqstat_doublefault & SEQSTAT_EXCAUSE,
            initial_pda_coreb.retx_doublefault);
        printk(KERN_NOTICE "   DCPLB_FAULT_ADDR: %pF\n",
            initial_pda_coreb.dcplb_doublefault_addr);
        printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %pF\n",
            initial_pda_coreb.icplb_doublefault_addr);
#endif
        printk(KERN_NOTICE " The instruction at %pF caused a double exception\n",
            initial_pda_coreb.retx);
    }

    /*
     * We want the D-cache to be enabled early, in case the atomic
     * support code emulates cache coherence (see
     * __ARCH_SYNC_CORE_DCACHE).
     */
    init_exception_vectors();

    local_irq_disable();

    /* Attach the new idle task to the global mm. */
    atomic_inc(&mm->mm_users);
    atomic_inc(&mm->mm_count);
    current->active_mm = mm;

    preempt_disable();

    setup_secondary(cpu);

    platform_secondary_init(cpu);

    /* setup local core timer */
    bfin_local_timer_setup();

    local_irq_enable();

    bfin_setup_caches(cpu);

    notify_cpu_starting(cpu);
    /*
     * Calibrate loops per jiffy value.
     * IRQs need to be enabled here - D-cache can be invalidated
     * in timer irq handler, so core B can read correct jiffies.
     */
    calibrate_delay();

    cpu_idle();
}

void __init smp_prepare_boot_cpu(void)
{
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
    platform_prepare_cpus(max_cpus);
    bfin_ipi_init();
    platform_request_ipi(IRQ_SUPPLE_0, ipi_handler_int0);
    platform_request_ipi(IRQ_SUPPLE_1, ipi_handler_int1);
}

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

    for_each_online_cpu(cpu)
        bogosum += 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 smp_icache_flush_range_others(unsigned long start, unsigned long end)
{
    smp_flush_data.start = start;
    smp_flush_data.end = end;

    preempt_disable();
    if (smp_call_function(&ipi_flush_icache, &smp_flush_data, 1))
        printk(KERN_WARNING "SMP: failed to run I-cache flush request on other CPUs\n");
    preempt_enable();
}
EXPORT_SYMBOL_GPL(smp_icache_flush_range_others);

#ifdef __ARCH_SYNC_CORE_ICACHE
unsigned long icache_invld_count[NR_CPUS];
void resync_core_icache(void)
{
    unsigned int cpu = get_cpu();
    blackfin_invalidate_entire_icache();
    icache_invld_count[cpu]++;
    put_cpu();
}
EXPORT_SYMBOL(resync_core_icache);
#endif

#ifdef __ARCH_SYNC_CORE_DCACHE
unsigned long dcache_invld_count[NR_CPUS];
unsigned long barrier_mask __attribute__ ((__section__(".l2.bss")));

void resync_core_dcache(void)
{
    unsigned int cpu = get_cpu();
    blackfin_invalidate_entire_dcache();
    dcache_invld_count[cpu]++;
    put_cpu();
}
EXPORT_SYMBOL(resync_core_dcache);
#endif

#ifdef CONFIG_HOTPLUG_CPU
int __cpuexit __cpu_disable(void)
{
    unsigned int cpu = smp_processor_id();

    if (cpu == 0)
        return -EPERM;

    set_cpu_online(cpu, false);
    return 0;
}

static DECLARE_COMPLETION(cpu_killed);

int __cpuexit __cpu_die(unsigned int cpu)
{
    return wait_for_completion_timeout(&cpu_killed, 5000);
}

void cpu_die(void)
{
    complete(&cpu_killed);

    atomic_dec(&init_mm.mm_users);
    atomic_dec(&init_mm.mm_count);

    local_irq_disable();
    platform_cpu_die();
}
#endif