arch/arm/mach-omap2/omap-hotplug.c

/*
 * OMAP4 SMP cpu-hotplug support
 *
 * Copyright (C) 2010 Texas Instruments, Inc.
 * Author:
 *      Santosh Shilimkar <santosh.shilimkar@ti.com>
 *
 * Platform file needed for the OMAP4 SMP. This file is based on arm
 * realview smp platform.
 * Copyright (c) 2002 ARM Limited.
 *
 * 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 <linux/completion.h>

#include <asm/cacheflush.h>
#include <mach/omap4-common.h>

static DECLARE_COMPLETION(cpu_killed);

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

/*
 * platform-specific code to shutdown a CPU
 * Called with IRQs disabled
 */
void platform_cpu_die(unsigned int cpu)
{
	unsigned int this_cpu = hard_smp_processor_id();

	if (cpu != this_cpu) {
		pr_crit("platform_cpu_die running on %u, should be %u\n",
			   this_cpu, cpu);
		BUG();
	}
	pr_notice("CPU%u: shutdown\n", cpu);
	complete(&cpu_killed);
	flush_cache_all();
	dsb();

	/*
	 * we're ready for shutdown now, so do it
	 */
	if (omap_modify_auxcoreboot0(0x0, 0x200) != 0x0)
		printk(KERN_CRIT "Secure clear status failed\n");

	for (;;) {
		/*
		 * Execute WFI
		 */
		do_wfi();

		if (omap_read_auxcoreboot0() == cpu) {
			/*
			 * OK, proper wakeup, we're done
			 */
			break;
		}
		pr_debug("CPU%u: spurious wakeup call\n", cpu);
	}
}

int platform_cpu_disable(unsigned int cpu)
{
	/*
	 * we don't allow CPU 0 to be shutdown (it is still too special
	 * e.g. clock tick interrupts)
	 */
	return cpu == 0 ? -EPERM : 0;
}