Add linux-next specific files for 20110831
[linux-2.6/next.git] / arch / powerpc / kernel / idle.c
blob39a2baa6ad58aec28a3c1d0782753569bbb51f6e
1 /*
2 * Idle daemon for PowerPC. Idle daemon will handle any action
3 * that needs to be taken when the system becomes idle.
5 * Originally written by Cort Dougan (cort@cs.nmt.edu).
6 * Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
7 * Paul Mackerras and others.
9 * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
11 * Additional shared processor, SMT, and firmware support
12 * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
14 * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
16 * This program is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU General Public License
18 * as published by the Free Software Foundation; either version
19 * 2 of the License, or (at your option) any later version.
22 #include <linux/sched.h>
23 #include <linux/kernel.h>
24 #include <linux/smp.h>
25 #include <linux/cpu.h>
26 #include <linux/sysctl.h>
27 #include <linux/tick.h>
29 #include <asm/system.h>
30 #include <asm/processor.h>
31 #include <asm/cputable.h>
32 #include <asm/time.h>
33 #include <asm/machdep.h>
34 #include <asm/smp.h>
36 #ifdef CONFIG_HOTPLUG_CPU
37 #define cpu_should_die() cpu_is_offline(smp_processor_id())
38 #else
39 #define cpu_should_die() 0
40 #endif
42 static int __init powersave_off(char *arg)
44 ppc_md.power_save = NULL;
45 return 0;
47 __setup("powersave=off", powersave_off);
50 * The body of the idle task.
52 void cpu_idle(void)
54 if (ppc_md.idle_loop)
55 ppc_md.idle_loop(); /* doesn't return */
57 set_thread_flag(TIF_POLLING_NRFLAG);
58 while (1) {
59 tick_nohz_stop_sched_tick(1);
60 while (!need_resched() && !cpu_should_die()) {
61 ppc64_runlatch_off();
63 if (ppc_md.power_save) {
64 clear_thread_flag(TIF_POLLING_NRFLAG);
66 * smp_mb is so clearing of TIF_POLLING_NRFLAG
67 * is ordered w.r.t. need_resched() test.
69 smp_mb();
70 local_irq_disable();
72 /* Don't trace irqs off for idle */
73 stop_critical_timings();
75 /* check again after disabling irqs */
76 if (!need_resched() && !cpu_should_die())
77 ppc_md.power_save();
79 start_critical_timings();
81 local_irq_enable();
82 set_thread_flag(TIF_POLLING_NRFLAG);
84 } else {
86 * Go into low thread priority and possibly
87 * low power mode.
89 HMT_low();
90 HMT_very_low();
94 HMT_medium();
95 ppc64_runlatch_on();
96 tick_nohz_restart_sched_tick();
97 preempt_enable_no_resched();
98 if (cpu_should_die())
99 cpu_die();
100 schedule();
101 preempt_disable();
105 int powersave_nap;
107 #ifdef CONFIG_SYSCTL
109 * Register the sysctl to set/clear powersave_nap.
111 static ctl_table powersave_nap_ctl_table[]={
113 .procname = "powersave-nap",
114 .data = &powersave_nap,
115 .maxlen = sizeof(int),
116 .mode = 0644,
117 .proc_handler = proc_dointvec,
121 static ctl_table powersave_nap_sysctl_root[] = {
123 .procname = "kernel",
124 .mode = 0555,
125 .child = powersave_nap_ctl_table,
130 static int __init
131 register_powersave_nap_sysctl(void)
133 register_sysctl_table(powersave_nap_sysctl_root);
135 return 0;
137 __initcall(register_powersave_nap_sysctl);
138 #endif