arch/openrisc/kernel/idle.c

   1 /*
   2  * OpenRISC idle.c
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  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  * Idle daemon for or32.  Idle daemon will handle any action
  18  * that needs to be taken when the system becomes idle.
  19  */
  20
  21 #include <linux/errno.h>
  22 #include <linux/sched.h>
  23 #include <linux/kernel.h>
  24 #include <linux/mm.h>
  25 #include <linux/smp.h>
  26 #include <linux/stddef.h>
  27 #include <linux/unistd.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/slab.h>
  30 #include <linux/tick.h>
  31
  32 #include <asm/pgtable.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/io.h>
  35 #include <asm/processor.h>
  36 #include <asm/mmu.h>
  37 #include <asm/cache.h>
  38 #include <asm/pgalloc.h>
  39
  40 void (*powersave) (void) = NULL;
  41
  42 static inline void pm_idle(void)
  43 {
  44         barrier();
  45 }
  46
  47 void cpu_idle(void)
  48 {
  49         set_thread_flag(TIF_POLLING_NRFLAG);
  50
  51         /* endless idle loop with no priority at all */
  52         while (1) {
  53                 tick_nohz_idle_enter();
  54                 rcu_idle_enter();
  55
  56                 while (!need_resched()) {
  57                         check_pgt_cache();
  58                         rmb();
  59
  60                         clear_thread_flag(TIF_POLLING_NRFLAG);
  61
  62                         local_irq_disable();
  63                         /* Don't trace irqs off for idle */
  64                         stop_critical_timings();
  65                         if (!need_resched() && powersave != NULL)
  66                                 powersave();
  67                         start_critical_timings();
  68                         local_irq_enable();
  69                         set_thread_flag(TIF_POLLING_NRFLAG);
  70                 }
  71
  72                 rcu_idle_exit();
  73                 tick_nohz_idle_exit();
  74                 preempt_enable_no_resched();
  75                 schedule();
  76                 preempt_disable();
  77         }
  78 }