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