LXR linux/arch/powerpc/kernel/idle.c

   1/*
   2 * Idle daemon for PowerPC.  Idle daemon will handle any action
   3 * that needs to be taken when the system becomes idle.
   4 *
   5 * Originally written by Cort Dougan (cort@cs.nmt.edu).
   6 * Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
   7 * Paul Mackerras and others.
   8 *
   9 * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
  10 *
  11 * Additional shared processor, SMT, and firmware support
  12 *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
  13 *
  14 * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
  15 *
  16 * This program is free software; you can redistribute it and/or
  17 * modify it under the terms of the GNU General Public License
  18 * as published by the Free Software Foundation; either version
  19 * 2 of the License, or (at your option) any later version.
  20 */
  21
  22#include <linux/sched.h>
  23#include <linux/kernel.h>
  24#include <linux/smp.h>
  25#include <linux/cpu.h>
  26#include <linux/sysctl.h>
  27#include <linux/tick.h>
  28
  29#include <asm/processor.h>
  30#include <asm/cputable.h>
  31#include <asm/time.h>
  32#include <asm/machdep.h>
  33#include <asm/runlatch.h>
  34#include <asm/smp.h>
  35
  36
  37unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
  38EXPORT_SYMBOL(cpuidle_disable);
  39
  40static int __init powersave_off(char *arg)
  41{
  42        ppc_md.power_save = NULL;
  43        cpuidle_disable = IDLE_POWERSAVE_OFF;
  44        return 0;
  45}
  46__setup("powersave=off", powersave_off);
  47
  48#ifdef CONFIG_HOTPLUG_CPU
  49void arch_cpu_idle_dead(void)
  50{
  51        sched_preempt_enable_no_resched();
  52        cpu_die();
  53}
  54#endif
  55
  56void arch_cpu_idle(void)
  57{
  58        ppc64_runlatch_off();
  59
  60        if (ppc_md.power_save) {
  61                ppc_md.power_save();
  62                /*
  63                 * Some power_save functions return with
  64                 * interrupts enabled, some don't.
  65                 */
  66                if (irqs_disabled())
  67                        local_irq_enable();
  68        } else {
  69                local_irq_enable();
  70                /*
  71                 * Go into low thread priority and possibly
  72                 * low power mode.
  73                 */
  74                HMT_low();
  75                HMT_very_low();
  76        }
  77
  78        HMT_medium();
  79        ppc64_runlatch_on();
  80}
  81
  82int powersave_nap;
  83
  84#ifdef CONFIG_SYSCTL
  85/*
  86 * Register the sysctl to set/clear powersave_nap.
  87 */
  88static struct ctl_table powersave_nap_ctl_table[] = {
  89        {
  90                .procname       = "powersave-nap",
  91                .data           = &powersave_nap,
  92                .maxlen         = sizeof(int),
  93                .mode           = 0644,
  94                .proc_handler   = proc_dointvec,
  95        },
  96        {}
  97};
  98static struct ctl_table powersave_nap_sysctl_root[] = {
  99        {
 100                .procname       = "kernel",
 101                .mode           = 0555,
 102                .child          = powersave_nap_ctl_table,
 103        },
 104        {}
 105};
 106
 107static int __init
 108register_powersave_nap_sysctl(void)
 109{
 110        register_sysctl_table(powersave_nap_sysctl_root);
 111
 112        return 0;
 113}
 114__initcall(register_powersave_nap_sysctl);
 115#endif
 116