blob: aaff0037fcd7ad89269154f5ac70076bb8a97278 [file] [log] [blame]
Paul Mundt1da11802008-11-26 15:52:44 +09001/*
2 * The idle loop for all SuperH platforms.
3 *
Paul Mundt2e046b92009-06-19 14:40:51 +09004 * Copyright (C) 2002 - 2009 Paul Mundt
Paul Mundt1da11802008-11-26 15:52:44 +09005 *
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>
Paul Mundt2e046b92009-06-19 14:40:51 +090018#include <linux/smp.h>
Paul Mundt1da11802008-11-26 15:52:44 +090019#include <asm/pgalloc.h>
20#include <asm/system.h>
21#include <asm/atomic.h>
22
23static int hlt_counter;
Paul Mundtf533c3d2009-10-16 17:20:58 +090024void (*pm_idle)(void) = NULL;
Paul Mundt1da11802008-11-26 15:52:44 +090025void (*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
Paul Mundtf533c3d2009-10-16 17:20:58 +090042static inline int hlt_works(void)
Paul Mundt1da11802008-11-26 15:52:44 +090043{
Paul Mundtf533c3d2009-10-16 17:20:58 +090044 return !hlt_counter;
Paul Mundt1da11802008-11-26 15:52:44 +090045}
46
Paul Mundtf533c3d2009-10-16 17:20:58 +090047/*
48 * On SMP it's slightly faster (but much more power-consuming!)
49 * to poll the ->work.need_resched flag instead of waiting for the
50 * cross-CPU IPI to arrive. Use this option with caution.
51 */
52static void poll_idle(void)
53{
54 local_irq_enable();
55 while (!need_resched())
56 cpu_relax();
57}
58
59void default_idle(void)
60{
61 if (hlt_works()) {
62 clear_thread_flag(TIF_POLLING_NRFLAG);
63 smp_mb__after_clear_bit();
64
65 if (!need_resched()) {
66 local_irq_enable();
67 cpu_sleep();
Paul Mundt9dbe00a2009-10-16 17:55:59 +090068 } else
69 local_irq_enable();
Paul Mundtf533c3d2009-10-16 17:20:58 +090070
71 set_thread_flag(TIF_POLLING_NRFLAG);
72 } else
73 poll_idle();
74}
75
76/*
77 * The idle thread. There's no useful work to be done, so just try to conserve
78 * power and have a low exit latency (ie sit in a loop waiting for somebody to
79 * say that they'd like to reschedule)
80 */
Paul Mundt1da11802008-11-26 15:52:44 +090081void cpu_idle(void)
82{
Paul Mundtf533c3d2009-10-16 17:20:58 +090083 unsigned int cpu = smp_processor_id();
84
Paul Mundt1da11802008-11-26 15:52:44 +090085 set_thread_flag(TIF_POLLING_NRFLAG);
86
87 /* endless idle loop with no priority at all */
88 while (1) {
Paul Mundt1da11802008-11-26 15:52:44 +090089 tick_nohz_stop_sched_tick(1);
Paul Mundt1da11802008-11-26 15:52:44 +090090
Paul Mundtf533c3d2009-10-16 17:20:58 +090091 while (!need_resched() && cpu_online(cpu)) {
Paul Mundt0e6d4982009-10-16 17:27:58 +090092 check_pgt_cache();
93 rmb();
94
Paul Mundtf533c3d2009-10-16 17:20:58 +090095 local_irq_disable();
96 /* Don't trace irqs off for idle */
97 stop_critical_timings();
98 pm_idle();
99 /*
100 * Sanity check to ensure that pm_idle() returns
101 * with IRQs enabled
102 */
103 WARN_ON(irqs_disabled());
104 start_critical_timings();
105 }
106
107 tick_nohz_restart_sched_tick();
Paul Mundt1da11802008-11-26 15:52:44 +0900108 preempt_enable_no_resched();
109 schedule();
110 preempt_disable();
Paul Mundt1da11802008-11-26 15:52:44 +0900111 }
112}
Paul Mundt2e046b92009-06-19 14:40:51 +0900113
Paul Mundtf533c3d2009-10-16 17:20:58 +0900114void __cpuinit select_idle_routine(void)
115{
116 /*
117 * If a platform has set its own idle routine, leave it alone.
118 */
119 if (pm_idle)
120 return;
121
122 if (hlt_works())
123 pm_idle = default_idle;
124 else
125 pm_idle = poll_idle;
126}
127
Paul Mundt2e046b92009-06-19 14:40:51 +0900128static void do_nothing(void *unused)
129{
130}
131
132/*
133 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
134 * pm_idle and update to new pm_idle value. Required while changing pm_idle
135 * handler on SMP systems.
136 *
137 * Caller must have changed pm_idle to the new value before the call. Old
138 * pm_idle value will not be used by any CPU after the return of this function.
139 */
140void cpu_idle_wait(void)
141{
142 smp_mb();
143 /* kick all the CPUs so that they exit out of pm_idle */
144 smp_call_function(do_nothing, NULL, 1);
145}
146EXPORT_SYMBOL_GPL(cpu_idle_wait);