sysctl: Drop & in front of every proc_handler.
[linux-2.6.git] / arch / powerpc / kernel / idle.c
1 /*
2  * Idle daemon for PowerPC.  Idle daemon will handle any action
3  * that needs to be taken when the system becomes idle.
4  *
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.
8  *
9  * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
10  *
11  * Additional shared processor, SMT, and firmware support
12  *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
13  *
14  * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
15  *
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.
20  */
21
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>
28
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>
35
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
41
42 static int __init powersave_off(char *arg)
43 {
44         ppc_md.power_save = NULL;
45         return 0;
46 }
47 __setup("powersave=off", powersave_off);
48
49 /*
50  * The body of the idle task.
51  */
52 void cpu_idle(void)
53 {
54         if (ppc_md.idle_loop)
55                 ppc_md.idle_loop();     /* doesn't return */
56
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();
62
63                         if (ppc_md.power_save) {
64                                 clear_thread_flag(TIF_POLLING_NRFLAG);
65                                 /*
66                                  * smp_mb is so clearing of TIF_POLLING_NRFLAG
67                                  * is ordered w.r.t. need_resched() test.
68                                  */
69                                 smp_mb();
70                                 local_irq_disable();
71
72                                 /* Don't trace irqs off for idle */
73                                 stop_critical_timings();
74
75                                 /* check again after disabling irqs */
76                                 if (!need_resched() && !cpu_should_die())
77                                         ppc_md.power_save();
78
79                                 start_critical_timings();
80
81                                 local_irq_enable();
82                                 set_thread_flag(TIF_POLLING_NRFLAG);
83
84                         } else {
85                                 /*
86                                  * Go into low thread priority and possibly
87                                  * low power mode.
88                                  */
89                                 HMT_low();
90                                 HMT_very_low();
91                         }
92                 }
93
94                 HMT_medium();
95                 ppc64_runlatch_on();
96                 tick_nohz_restart_sched_tick();
97                 if (cpu_should_die())
98                         cpu_die();
99                 preempt_enable_no_resched();
100                 schedule();
101                 preempt_disable();
102         }
103 }
104
105 int powersave_nap;
106
107 #ifdef CONFIG_SYSCTL
108 /*
109  * Register the sysctl to set/clear powersave_nap.
110  */
111 static ctl_table powersave_nap_ctl_table[]={
112         {
113                 .procname       = "powersave-nap",
114                 .data           = &powersave_nap,
115                 .maxlen         = sizeof(int),
116                 .mode           = 0644,
117                 .proc_handler   = proc_dointvec,
118         },
119         {}
120 };
121 static ctl_table powersave_nap_sysctl_root[] = {
122         {
123                 .procname       = "kernel",
124                 .mode           = 0555,
125                 .child          = powersave_nap_ctl_table,
126         },
127         {}
128 };
129
130 static int __init
131 register_powersave_nap_sysctl(void)
132 {
133         register_sysctl_table(powersave_nap_sysctl_root);
134
135         return 0;
136 }
137 __initcall(register_powersave_nap_sysctl);
138 #endif