Merge branch 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/dtor/input
[linux-2.6] / 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
28 #include <asm/system.h>
29 #include <asm/processor.h>
30 #include <asm/cputable.h>
31 #include <asm/time.h>
32 #include <asm/machdep.h>
33 #include <asm/smp.h>
34
35 #ifdef CONFIG_HOTPLUG_CPU
36 #define cpu_should_die()        (cpu_is_offline(smp_processor_id()) && \
37                                  system_state == SYSTEM_RUNNING)
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                 while (!need_resched() && !cpu_should_die()) {
60                         ppc64_runlatch_off();
61
62                         if (ppc_md.power_save) {
63                                 clear_thread_flag(TIF_POLLING_NRFLAG);
64                                 /*
65                                  * smp_mb is so clearing of TIF_POLLING_NRFLAG
66                                  * is ordered w.r.t. need_resched() test.
67                                  */
68                                 smp_mb();
69                                 local_irq_disable();
70
71                                 /* check again after disabling irqs */
72                                 if (!need_resched() && !cpu_should_die())
73                                         ppc_md.power_save();
74
75                                 local_irq_enable();
76                                 set_thread_flag(TIF_POLLING_NRFLAG);
77
78                         } else {
79                                 /*
80                                  * Go into low thread priority and possibly
81                                  * low power mode.
82                                  */
83                                 HMT_low();
84                                 HMT_very_low();
85                         }
86                 }
87
88                 HMT_medium();
89                 ppc64_runlatch_on();
90                 if (cpu_should_die())
91                         cpu_die();
92                 preempt_enable_no_resched();
93                 schedule();
94                 preempt_disable();
95         }
96 }
97
98 int powersave_nap;
99
100 #ifdef CONFIG_SYSCTL
101 /*
102  * Register the sysctl to set/clear powersave_nap.
103  */
104 static ctl_table powersave_nap_ctl_table[]={
105         {
106                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
107                 .procname       = "powersave-nap",
108                 .data           = &powersave_nap,
109                 .maxlen         = sizeof(int),
110                 .mode           = 0644,
111                 .proc_handler   = &proc_dointvec,
112         },
113         {}
114 };
115 static ctl_table powersave_nap_sysctl_root[] = {
116         {
117                 .ctl_name       = CTL_KERN,
118                 .procname       = "kernel",
119                 .mode           = 0755,
120                 .child          = powersave_nap_ctl_table,
121         },
122         {}
123 };
124
125 static int __init
126 register_powersave_nap_sysctl(void)
127 {
128         register_sysctl_table(powersave_nap_sysctl_root);
129
130         return 0;
131 }
132 __initcall(register_powersave_nap_sysctl);
133 #endif