arch/ppc64/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  *
   7  * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
   8  *
   9  * Additional shared processor, SMT, and firmware support
  10  *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version
  15  * 2 of the License, or (at your option) any later version.
  16  */
  17
  18 #include <linux/config.h>
  19 #include <linux/sched.h>
  20 #include <linux/kernel.h>
  21 #include <linux/smp.h>
  22 #include <linux/cpu.h>
  23 #include <linux/sysctl.h>
  24
  25 #include <asm/system.h>
  26 #include <asm/processor.h>
  27 #include <asm/cputable.h>
  28 #include <asm/time.h>
  29 #include <asm/systemcfg.h>
  30 #include <asm/machdep.h>
  31 #include <asm/smp.h>
  32
  33 extern void power4_idle(void);
  34
  35 void default_idle(void)
  36 {
  37         unsigned int cpu = smp_processor_id();
  38         set_thread_flag(TIF_POLLING_NRFLAG);
  39
  40         while (1) {
  41                 if (!need_resched()) {
  42                         while (!need_resched() && !cpu_is_offline(cpu)) {
  43                                 ppc64_runlatch_off();
  44
  45                                 /*
  46                                  * Go into low thread priority and possibly
  47                                  * low power mode.
  48                                  */
  49                                 HMT_low();
  50                                 HMT_very_low();
  51                         }
  52
  53                         HMT_medium();
  54                 }
  55
  56                 ppc64_runlatch_on();
  57                 preempt_enable_no_resched();
  58                 schedule();
  59                 preempt_disable();
  60                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
  61                         cpu_die();
  62         }
  63 }
  64
  65 void native_idle(void)
  66 {
  67         while (1) {
  68                 ppc64_runlatch_off();
  69
  70                 if (!need_resched())
  71                         power4_idle();
  72
  73                 if (need_resched()) {
  74                         ppc64_runlatch_on();
  75                         preempt_enable_no_resched();
  76                         schedule();
  77                         preempt_disable();
  78                 }
  79
  80                 if (cpu_is_offline(smp_processor_id()) &&
  81                     system_state == SYSTEM_RUNNING)
  82                         cpu_die();
  83         }
  84 }
  85
  86 void cpu_idle(void)
  87 {
  88         BUG_ON(NULL == ppc_md.idle_loop);
  89         ppc_md.idle_loop();
  90 }
  91
  92 int powersave_nap;
  93
  94 #ifdef CONFIG_SYSCTL
  95 /*
  96  * Register the sysctl to set/clear powersave_nap.
  97  */
  98 static ctl_table powersave_nap_ctl_table[]={
  99         {
 100                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
 101                 .procname       = "powersave-nap",
 102                 .data           = &powersave_nap,
 103                 .maxlen         = sizeof(int),
 104                 .mode           = 0644,
 105                 .proc_handler   = &proc_dointvec,
 106         },
 107         { 0, },
 108 };
 109 static ctl_table powersave_nap_sysctl_root[] = {
 110         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
 111         { 0,},
 112 };
 113
 114 static int __init
 115 register_powersave_nap_sysctl(void)
 116 {
 117         register_sysctl_table(powersave_nap_sysctl_root, 0);
 118
 119         return 0;
 120 }
 121 __initcall(register_powersave_nap_sysctl);
 122 #endif