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 #include <linux/cpu.h>
  26
  27 #include <asm/pgtable.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/system.h>
  30 #include <asm/io.h>
  31 #include <asm/mmu.h>
  32 #include <asm/cache.h>
  33 #include <asm/cputable.h>
  34 #include <asm/machdep.h>
  35 #include <asm/smp.h>
  36
  37 void default_idle(void)
  38 {
  39         void (*powersave)(void);
  40         int cpu = smp_processor_id();
  41
  42         powersave = ppc_md.power_save;
  43
  44         if (!need_resched()) {
  45                 if (powersave != NULL)
  46                         powersave();
  47 #ifdef CONFIG_SMP
  48                 else {
  49                         set_thread_flag(TIF_POLLING_NRFLAG);
  50                         while (!need_resched() && !cpu_is_offline(cpu))
  51                                 barrier();
  52                         clear_thread_flag(TIF_POLLING_NRFLAG);
  53                 }
  54 #endif
  55         }
  56 }
  57
  58 /*
  59  * The body of the idle task.
  60  */
  61 void cpu_idle(void)
  62 {
  63         int cpu = smp_processor_id();
  64
  65         for (;;) {
  66                 if (ppc_md.idle != NULL)
  67                         ppc_md.idle();
  68                 else
  69                         default_idle();
  70                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
  71                         cpu_die();
  72                 if (need_resched()) {
  73                         preempt_enable_no_resched();
  74                         schedule();
  75                         preempt_disable();
  76                 }
  77
  78         }
  79 }
  80
  81 #if defined(CONFIG_SYSCTL) && defined(CONFIG_6xx)
  82 /*
  83  * Register the sysctl to set/clear powersave_nap.
  84  */
  85 extern int powersave_nap;
  86
  87 static ctl_table powersave_nap_ctl_table[]={
  88         {
  89                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
  90                 .procname       = "powersave-nap",
  91                 .data           = &powersave_nap,
  92                 .maxlen         = sizeof(int),
  93                 .mode           = 0644,
  94                 .proc_handler   = &proc_dointvec,
  95         },
  96         { 0, },
  97 };
  98 static ctl_table powersave_nap_sysctl_root[] = {
  99         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
 100         { 0,},
 101 };
 102
 103 static int __init
 104 register_powersave_nap_sysctl(void)
 105 {
 106         register_sysctl_table(powersave_nap_sysctl_root, 0);
 107
 108         return 0;
 109 }
 110
 111 __initcall(register_powersave_nap_sysctl);
 112 #endif