blob: 9c7099ebfe1456b97c3185dff1ad29e2c09c2bc3 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
/*
* The idle loop for all SuperH platforms.
*
* Copyright (C) 2002 - 2009 Paul Mundt
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/preempt.h>
#include <linux/thread_info.h>
#include <linux/irqflags.h>
#include <linux/smp.h>
#include <linux/cpuidle.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/smp.h>
static void (*pm_idle)(void);
static int hlt_counter;
static int __init nohlt_setup(char *__unused)
{
hlt_counter = 1;
return 1;
}
__setup("nohlt", nohlt_setup);
static int __init hlt_setup(char *__unused)
{
hlt_counter = 0;
return 1;
}
__setup("hlt", hlt_setup);
static inline int hlt_works(void)
{
return !hlt_counter;
}
/*
* On SMP it's slightly faster (but much more power-consuming!)
* to poll the ->work.need_resched flag instead of waiting for the
* cross-CPU IPI to arrive. Use this option with caution.
*/
static void poll_idle(void)
{
local_irq_enable();
while (!need_resched())
cpu_relax();
}
void default_idle(void)
{
if (hlt_works()) {
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb__after_clear_bit();
set_bl_bit();
if (!need_resched()) {
local_irq_enable();
cpu_sleep();
} else
local_irq_enable();
set_thread_flag(TIF_POLLING_NRFLAG);
clear_bl_bit();
} else
poll_idle();
}
/*
* The idle thread. There's no useful work to be done, so just try to conserve
* power and have a low exit latency (ie sit in a loop waiting for somebody to
* say that they'd like to reschedule)
*/
void cpu_idle(void)
{
unsigned int cpu = smp_processor_id();
set_thread_flag(TIF_POLLING_NRFLAG);
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick(1);
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
if (cpuidle_call_idle())
pm_idle();
/*
* Sanity check to ensure that pm_idle() returns
* with IRQs enabled
*/
WARN_ON(irqs_disabled());
start_critical_timings();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
void __init select_idle_routine(void)
{
/*
* If a platform has set its own idle routine, leave it alone.
*/
if (pm_idle)
return;
if (hlt_works())
pm_idle = default_idle;
else
pm_idle = poll_idle;
}
static void do_nothing(void *unused)
{
}
void stop_this_cpu(void *unused)
{
local_irq_disable();
set_cpu_online(smp_processor_id(), false);
for (;;)
cpu_sleep();
}
/*
* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
* pm_idle and update to new pm_idle value. Required while changing pm_idle
* handler on SMP systems.
*
* Caller must have changed pm_idle to the new value before the call. Old
* pm_idle value will not be used by any CPU after the return of this function.
*/
void cpu_idle_wait(void)
{
smp_mb();
/* kick all the CPUs so that they exit out of pm_idle */
smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
|
