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/machdep.h>
  30 #include <asm/smp.h>
  31
  32 extern void power4_idle(void);
  33
  34 void default_idle(void)
  35 {
  36         unsigned int cpu = smp_processor_id();
  37         set_thread_flag(TIF_POLLING_NRFLAG);
  38
  39         while (1) {
  40                 if (!need_resched()) {
  41                         while (!need_resched() && !cpu_is_offline(cpu)) {
  42                                 ppc64_runlatch_off();
  43
  44                                 /*
  45                                  * Go into low thread priority and possibly
  46                                  * low power mode.
  47                                  */
  48                                 HMT_low();
  49                                 HMT_very_low();
  50                         }
  51
  52                         HMT_medium();
  53                 }
  54
  55                 ppc64_runlatch_on();
  56                 preempt_enable_no_resched();
  57                 schedule();
  58                 preempt_disable();
  59                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
  60                         cpu_die();
  61         }
  62 }
  63
  64 void native_idle(void)
  65 {
  66         while (1) {
  67                 ppc64_runlatch_off();
  68
  69                 if (!need_resched())
  70                         power4_idle();
  71
  72                 if (need_resched()) {
  73                         ppc64_runlatch_on();
  74                         preempt_enable_no_resched();
  75                         schedule();
  76                         preempt_disable();
  77                 }
  78
  79                 if (cpu_is_offline(smp_processor_id()) &&
  80                     system_state == SYSTEM_RUNNING)
  81                         cpu_die();
  82         }
  83 }
  84
  85 void cpu_idle(void)
  86 {
  87         BUG_ON(NULL == ppc_md.idle_loop);
  88         ppc_md.idle_loop();
  89 }
  90
  91 int powersave_nap;
  92
  93 #ifdef CONFIG_SYSCTL
  94 /*
  95  * Register the sysctl to set/clear powersave_nap.
  96  */
  97 static ctl_table powersave_nap_ctl_table[]={
  98         {
  99                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
 100                 .procname       = "powersave-nap",
 101                 .data           = &powersave_nap,
 102                 .maxlen         = sizeof(int),
 103                 .mode           = 0644,
 104                 .proc_handler   = &proc_dointvec,
 105         },
 106         { 0, },
 107 };
 108 static ctl_table powersave_nap_sysctl_root[] = {
 109         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
 110         { 0,},
 111 };
 112
 113 static int __init
 114 register_powersave_nap_sysctl(void)
 115 {
 116         register_sysctl_table(powersave_nap_sysctl_root, 0);
 117
 118         return 0;
 119 }
 120 __initcall(register_powersave_nap_sysctl);
 121 #endif