arch/ppc/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  * Written by Cort Dougan (cort@cs.nmt.edu).  Subsequently hacked
   6  * on by Tom Rini, Armin Kuster, Paul Mackerras and others.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13 #include <linux/config.h>
  14 #include <linux/errno.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/smp_lock.h>
  20 #include <linux/stddef.h>
  21 #include <linux/unistd.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/slab.h>
  24 #include <linux/sysctl.h>
  25
  26 #include <asm/pgtable.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/system.h>
  29 #include <asm/io.h>
  30 #include <asm/mmu.h>
  31 #include <asm/cache.h>
  32 #include <asm/cputable.h>
  33 #include <asm/machdep.h>
  34
  35 void default_idle(void)
  36 {
  37         void (*powersave)(void);
  38
  39         powersave = ppc_md.power_save;
  40
  41         if (!need_resched()) {
  42                 if (powersave != NULL)
  43                         powersave();
  44 #ifdef CONFIG_SMP
  45                 else {
  46                         set_thread_flag(TIF_POLLING_NRFLAG);
  47                         while (!need_resched())
  48                                 barrier();
  49                         clear_thread_flag(TIF_POLLING_NRFLAG);
  50                 }
  51 #endif
  52         }
  53         if (need_resched())
  54                 schedule();
  55 }
  56
  57 /*
  58  * The body of the idle task.
  59  */
  60 void cpu_idle(void)
  61 {
  62         for (;;)
  63                 if (ppc_md.idle != NULL)
  64                         ppc_md.idle();
  65                 else
  66                         default_idle();
  67 }
  68
  69 #if defined(CONFIG_SYSCTL) && defined(CONFIG_6xx)
  70 /*
  71  * Register the sysctl to set/clear powersave_nap.
  72  */
  73 extern unsigned long powersave_nap;
  74
  75 static ctl_table powersave_nap_ctl_table[]={
  76         {
  77                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
  78                 .procname       = "powersave-nap",
  79                 .data           = &powersave_nap,
  80                 .maxlen         = sizeof(int),
  81                 .mode           = 0644,
  82                 .proc_handler   = &proc_dointvec,
  83         },
  84         { 0, },
  85 };
  86 static ctl_table powersave_nap_sysctl_root[] = {
  87         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
  88         { 0,},
  89 };
  90
  91 static int __init
  92 register_powersave_nap_sysctl(void)
  93 {
  94         register_sysctl_table(powersave_nap_sysctl_root, 0);
  95
  96         return 0;
  97 }
  98
  99 __initcall(register_powersave_nap_sysctl);
 100 #endif