909ea669af9159a3dd3341f69a623118e0693529
[linux-2.6.git] / arch / ppc64 / 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  *
7  * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
8  *
9  * Additional shared processor, SMT, and firmware support
10  *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
11  *
12  * This program is free software; you can redistribute it and/or
13  * modify it under the terms of the GNU General Public License
14  * as published by the Free Software Foundation; either version
15  * 2 of the License, or (at your option) any later version.
16  */
17
18 #include <linux/config.h>
19 #include <linux/sched.h>
20 #include <linux/kernel.h>
21 #include <linux/smp.h>
22 #include <linux/cpu.h>
23 #include <linux/sysctl.h>
24
25 #include <asm/system.h>
26 #include <asm/processor.h>
27 #include <asm/cputable.h>
28 #include <asm/time.h>
29 #include <asm/systemcfg.h>
30 #include <asm/machdep.h>
31 #include <asm/smp.h>
32
33 extern void power4_idle(void);
34
35 void default_idle(void)
36 {
37         long oldval;
38         unsigned int cpu = smp_processor_id();
39
40         while (1) {
41                 oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
42
43                 if (!oldval) {
44                         set_thread_flag(TIF_POLLING_NRFLAG);
45
46                         while (!need_resched() && !cpu_is_offline(cpu)) {
47                                 ppc64_runlatch_off();
48
49                                 /*
50                                  * Go into low thread priority and possibly
51                                  * low power mode.
52                                  */
53                                 HMT_low();
54                                 HMT_very_low();
55                         }
56
57                         HMT_medium();
58                         clear_thread_flag(TIF_POLLING_NRFLAG);
59                 } else {
60                         set_need_resched();
61                 }
62
63                 ppc64_runlatch_on();
64                 preempt_enable_no_resched();
65                 schedule();
66                 preempt_disable();
67                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
68                         cpu_die();
69         }
70 }
71
72 void native_idle(void)
73 {
74         while (1) {
75                 ppc64_runlatch_off();
76
77                 if (!need_resched())
78                         power4_idle();
79
80                 if (need_resched()) {
81                         ppc64_runlatch_on();
82                         preempt_enable_no_resched();
83                         schedule();
84                         preempt_disable();
85                 }
86
87                 if (cpu_is_offline(smp_processor_id()) &&
88                     system_state == SYSTEM_RUNNING)
89                         cpu_die();
90         }
91 }
92
93 void cpu_idle(void)
94 {
95         BUG_ON(NULL == ppc_md.idle_loop);
96         ppc_md.idle_loop();
97 }
98
99 int powersave_nap;
100
101 #ifdef CONFIG_SYSCTL
102 /*
103  * Register the sysctl to set/clear powersave_nap.
104  */
105 static ctl_table powersave_nap_ctl_table[]={
106         {
107                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
108                 .procname       = "powersave-nap",
109                 .data           = &powersave_nap,
110                 .maxlen         = sizeof(int),
111                 .mode           = 0644,
112                 .proc_handler   = &proc_dointvec,
113         },
114         { 0, },
115 };
116 static ctl_table powersave_nap_sysctl_root[] = {
117         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
118         { 0,},
119 };
120
121 static int __init
122 register_powersave_nap_sysctl(void)
123 {
124         register_sysctl_table(powersave_nap_sysctl_root, 0);
125
126         return 0;
127 }
128 __initcall(register_powersave_nap_sysctl);
129 #endif