arch/sh/kernel/idle.c

   1 /*
   2  * The idle loop for all SuperH platforms.
   3  *
   4  *  Copyright (C) 2002 - 2008  Paul Mundt
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/mm.h>
  13 #include <linux/pm.h>
  14 #include <linux/tick.h>
  15 #include <linux/preempt.h>
  16 #include <linux/thread_info.h>
  17 #include <linux/irqflags.h>
  18 #include <asm/pgalloc.h>
  19 #include <asm/system.h>
  20 #include <asm/atomic.h>
  21
  22 static int hlt_counter;
  23 void (*pm_idle)(void);
  24 void (*pm_power_off)(void);
  25 EXPORT_SYMBOL(pm_power_off);
  26
  27 static int __init nohlt_setup(char *__unused)
  28 {
  29         hlt_counter = 1;
  30         return 1;
  31 }
  32 __setup("nohlt", nohlt_setup);
  33
  34 static int __init hlt_setup(char *__unused)
  35 {
  36         hlt_counter = 0;
  37         return 1;
  38 }
  39 __setup("hlt", hlt_setup);
  40
  41 void default_idle(void)
  42 {
  43         if (!hlt_counter) {
  44                 clear_thread_flag(TIF_POLLING_NRFLAG);
  45                 smp_mb__after_clear_bit();
  46                 set_bl_bit();
  47                 stop_critical_timings();
  48
  49                 while (!need_resched())
  50                         cpu_sleep();
  51
  52                 start_critical_timings();
  53                 clear_bl_bit();
  54                 set_thread_flag(TIF_POLLING_NRFLAG);
  55         } else
  56                 while (!need_resched())
  57                         cpu_relax();
  58 }
  59
  60 void cpu_idle(void)
  61 {
  62         set_thread_flag(TIF_POLLING_NRFLAG);
  63
  64         /* endless idle loop with no priority at all */
  65         while (1) {
  66                 void (*idle)(void) = pm_idle;
  67
  68                 if (!idle)
  69                         idle = default_idle;
  70
  71                 tick_nohz_stop_sched_tick(1);
  72                 while (!need_resched())
  73                         idle();
  74                 tick_nohz_restart_sched_tick();
  75
  76                 preempt_enable_no_resched();
  77                 schedule();
  78                 preempt_disable();
  79                 check_pgt_cache();
  80         }
  81 }