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
  37 unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
  38 EXPORT_SYMBOL(cpuidle_disable);
  39
  40 static 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
  49 void arch_cpu_idle_dead(void)
  50 {
  51         sched_preempt_enable_no_resched();
  52         cpu_die();
  53 }
  54 #endif
  55
  56 void 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
  82 int powersave_nap;
  83
  84 #ifdef CONFIG_SYSCTL
  85 /*
  86  * Register the sysctl to set/clear powersave_nap.
  87  */
  88 static 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 };
  98 static struct ctl_table powersave_nap_sysctl_root[] = {
  99         {
 100                 .procname       = "kernel",
 101                 .mode           = 0555,
 102                 .child          = powersave_nap_ctl_table,
 103         },
 104         {}
 105 };
 106
 107 static int __init
 108 register_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