LXR linux/arch/sh/kernel/idle.c

   1/*
   2 * The idle loop for all SuperH platforms.
   3 *
   4 *  Copyright (C) 2002 - 2009  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 <linux/smp.h>
  19#include <asm/pgalloc.h>
  20#include <asm/system.h>
  21#include <asm/atomic.h>
  22
  23static int hlt_counter;
  24void (*pm_idle)(void);
  25void (*pm_power_off)(void);
  26EXPORT_SYMBOL(pm_power_off);
  27
  28static int __init nohlt_setup(char *__unused)
  29{
  30        hlt_counter = 1;
  31        return 1;
  32}
  33__setup("nohlt", nohlt_setup);
  34
  35static int __init hlt_setup(char *__unused)
  36{
  37        hlt_counter = 0;
  38        return 1;
  39}
  40__setup("hlt", hlt_setup);
  41
  42void default_idle(void)
  43{
  44        if (!hlt_counter) {
  45                clear_thread_flag(TIF_POLLING_NRFLAG);
  46                smp_mb__after_clear_bit();
  47                set_bl_bit();
  48                stop_critical_timings();
  49
  50                while (!need_resched())
  51                        cpu_sleep();
  52
  53                start_critical_timings();
  54                clear_bl_bit();
  55                set_thread_flag(TIF_POLLING_NRFLAG);
  56        } else
  57                while (!need_resched())
  58                        cpu_relax();
  59}
  60
  61void cpu_idle(void)
  62{
  63        set_thread_flag(TIF_POLLING_NRFLAG);
  64
  65        /* endless idle loop with no priority at all */
  66        while (1) {
  67                void (*idle)(void) = pm_idle;
  68
  69                if (!idle)
  70                        idle = default_idle;
  71
  72                tick_nohz_stop_sched_tick(1);
  73                while (!need_resched())
  74                        idle();
  75                tick_nohz_restart_sched_tick();
  76
  77                preempt_enable_no_resched();
  78                schedule();
  79                preempt_disable();
  80                check_pgt_cache();
  81        }
  82}
  83
  84static void do_nothing(void *unused)
  85{
  86}
  87
  88/*
  89 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
  90 * pm_idle and update to new pm_idle value. Required while changing pm_idle
  91 * handler on SMP systems.
  92 *
  93 * Caller must have changed pm_idle to the new value before the call. Old
  94 * pm_idle value will not be used by any CPU after the return of this function.
  95 */
  96void cpu_idle_wait(void)
  97{
  98        smp_mb();
  99        /* kick all the CPUs so that they exit out of pm_idle */
 100        smp_call_function(do_nothing, NULL, 1);
 101}
 102EXPORT_SYMBOL_GPL(cpu_idle_wait);
 103