hotplug.c

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/*
 *  Copyright (C) 2002 ARM Ltd.
 *  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/kernel.h>
#include <linux/errno.h>
#include <linux/smp.h>

#include <asm/cacheflush.h>
#include <asm/smp_plat.h>

#include "common.h"

static inline void cpu_enter_lowpower(void)
{
    /* Just flush the cache. Changing the coherency is not yet
     * available on msm. */
    flush_cache_all();
}

static inline void cpu_leave_lowpower(void)
{
}

static inline void platform_do_lowpower(unsigned int cpu)
{
    /* Just enter wfi for now. TODO: Properly shut off the cpu. */
    for (;;) {
        /*
         * here's the WFI
         */
        asm("wfi"
            :
            :
            : "memory", "cc");

        if (pen_release == cpu_logical_map(cpu)) {
            /*
             * OK, proper wakeup, we're done
             */
            break;
        }

        /*
         * getting here, means that we have come out of WFI without
         * having been woken up - this shouldn't happen
         *
         * The trouble is, letting people know about this is not really
         * possible, since we are currently running incoherently, and
         * therefore cannot safely call printk() or anything else
         */
        pr_debug("CPU%u: spurious wakeup call\n", cpu);
    }
}

/*
 * platform-specific code to shutdown a CPU
 *
 * Called with IRQs disabled
 */
void __ref msm_cpu_die(unsigned int cpu)
{
    /*
     * we're ready for shutdown now, so do it
     */
    cpu_enter_lowpower();
    platform_do_lowpower(cpu);

    /*
     * bring this CPU back into the world of cache
     * coherency, and then restore interrupts
     */
    cpu_leave_lowpower();
}