Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / cpu / idle.c
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1/*
2 * Generic entry point for the idle threads
3 */
4#include <linux/sched.h>
5#include <linux/cpu.h>
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6#include <linux/tick.h>
7#include <linux/mm.h>
a1a04ec3 8
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9#include <asm/tlb.h>
10
11#include <trace/events/power.h>
12
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13static int __read_mostly cpu_idle_force_poll;
14
15void cpu_idle_poll_ctrl(bool enable)
16{
17 if (enable) {
18 cpu_idle_force_poll++;
19 } else {
20 cpu_idle_force_poll--;
21 WARN_ON_ONCE(cpu_idle_force_poll < 0);
22 }
23}
24
25#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP
26static int __init cpu_idle_poll_setup(char *__unused)
27{
28 cpu_idle_force_poll = 1;
29 return 1;
30}
31__setup("nohlt", cpu_idle_poll_setup);
32
33static int __init cpu_idle_nopoll_setup(char *__unused)
34{
35 cpu_idle_force_poll = 0;
36 return 1;
37}
38__setup("hlt", cpu_idle_nopoll_setup);
39#endif
40
41static inline int cpu_idle_poll(void)
42{
b47430d3 43 rcu_idle_enter();
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44 trace_cpu_idle_rcuidle(0, smp_processor_id());
45 local_irq_enable();
46 while (!need_resched())
47 cpu_relax();
48 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
b47430d3 49 rcu_idle_exit();
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50 return 1;
51}
52
53/* Weak implementations for optional arch specific functions */
54void __weak arch_cpu_idle_prepare(void) { }
55void __weak arch_cpu_idle_enter(void) { }
56void __weak arch_cpu_idle_exit(void) { }
57void __weak arch_cpu_idle_dead(void) { }
58void __weak arch_cpu_idle(void)
59{
60 cpu_idle_force_poll = 1;
61}
62
63/*
64 * Generic idle loop implementation
65 */
66static void cpu_idle_loop(void)
67{
68 while (1) {
69 tick_nohz_idle_enter();
70
71 while (!need_resched()) {
72 check_pgt_cache();
73 rmb();
74
75 if (cpu_is_offline(smp_processor_id()))
76 arch_cpu_idle_dead();
77
78 local_irq_disable();
79 arch_cpu_idle_enter();
80
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81 /*
82 * In poll mode we reenable interrupts and spin.
83 *
84 * Also if we detected in the wakeup from idle
85 * path that the tick broadcast device expired
86 * for us, we don't want to go deep idle as we
87 * know that the IPI is going to arrive right
88 * away
89 */
90 if (cpu_idle_force_poll || tick_check_broadcast_expired()) {
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91 cpu_idle_poll();
92 } else {
93 current_clr_polling();
94 if (!need_resched()) {
95 stop_critical_timings();
96 rcu_idle_enter();
97 arch_cpu_idle();
98 WARN_ON_ONCE(irqs_disabled());
99 rcu_idle_exit();
100 start_critical_timings();
101 } else {
102 local_irq_enable();
103 }
104 current_set_polling();
105 }
106 arch_cpu_idle_exit();
107 }
108 tick_nohz_idle_exit();
109 schedule_preempt_disabled();
110 }
111}
112
113void cpu_startup_entry(enum cpuhp_state state)
114{
115 current_set_polling();
116 arch_cpu_idle_prepare();
117 cpu_idle_loop();
118}