kernel/power/smp.c

   1 /*
   2  * drivers/power/smp.c - Functions for stopping other CPUs.
   3  *
   4  * Copyright 2004 Pavel Machek <pavel@suse.cz>
   5  * Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz>
   6  *
   7  * This file is released under the GPLv2.
   8  */
   9
  10 #undef DEBUG
  11
  12 #include <linux/smp_lock.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/suspend.h>
  15 #include <linux/module.h>
  16 #include <linux/cpu.h>
  17 #include <asm/atomic.h>
  18 #include <asm/tlbflush.h>
  19
  20 /* This is protected by pm_sem semaphore */
  21 static cpumask_t frozen_cpus;
  22
  23 void disable_nonboot_cpus(void)
  24 {
  25         int cpu, error;
  26
  27         error = 0;
  28         cpus_clear(frozen_cpus);
  29         printk("Freezing cpus ...\n");
  30         for_each_online_cpu(cpu) {
  31                 if (cpu == 0)
  32                         continue;
  33                 error = cpu_down(cpu);
  34                 if (!error) {
  35                         cpu_set(cpu, frozen_cpus);
  36                         printk("CPU%d is down\n", cpu);
  37                         continue;
  38                 }
  39                 printk("Error taking cpu %d down: %d\n", cpu, error);
  40         }
  41         BUG_ON(raw_smp_processor_id() != 0);
  42         if (error)
  43                 panic("cpus not sleeping");
  44 }
  45
  46 void enable_nonboot_cpus(void)
  47 {
  48         int cpu, error;
  49
  50         printk("Thawing cpus ...\n");
  51         for_each_cpu_mask(cpu, frozen_cpus) {
  52                 error = cpu_up(cpu);
  53                 if (!error) {
  54                         printk("CPU%d is up\n", cpu);
  55                         continue;
  56                 }
  57                 printk("Error taking cpu %d up: %d\n", cpu, error);
  58                 panic("Not enough cpus");
  59         }
  60         cpus_clear(frozen_cpus);
  61 }
  62