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/system.h>
35 #include <asm/io.h>
36 #include <asm/processor.h>
37 #include <asm/mmu.h>
38 #include <asm/cache.h>
39 #include <asm/pgalloc.h>
40 
41 void (*powersave) (void) = NULL;
42 
pm_idle(void)43 static inline void pm_idle(void)
44 {
45 	barrier();
46 }
47 
cpu_idle(void)48 void cpu_idle(void)
49 {
50 	set_thread_flag(TIF_POLLING_NRFLAG);
51 
52 	/* endless idle loop with no priority at all */
53 	while (1) {
54 		tick_nohz_idle_enter();
55 		rcu_idle_enter();
56 
57 		while (!need_resched()) {
58 			check_pgt_cache();
59 			rmb();
60 
61 			clear_thread_flag(TIF_POLLING_NRFLAG);
62 
63 			local_irq_disable();
64 			/* Don't trace irqs off for idle */
65 			stop_critical_timings();
66 			if (!need_resched() && powersave != NULL)
67 				powersave();
68 			start_critical_timings();
69 			local_irq_enable();
70 			set_thread_flag(TIF_POLLING_NRFLAG);
71 		}
72 
73 		rcu_idle_exit();
74 		tick_nohz_idle_exit();
75 		preempt_enable_no_resched();
76 		schedule();
77 		preempt_disable();
78 	}
79 }
80