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>
33 #include <asm/machdep.h>
36 #ifdef CONFIG_HOTPLUG_CPU
37 #define cpu_should_die() cpu_is_offline(smp_processor_id())
39 #define cpu_should_die() 0
42 static int __init powersave_off(char *arg)
44 ppc_md.power_save = NULL;
47 __setup("powersave=off", powersave_off);
50 * The body of the idle task.
55 ppc_md.idle_loop(); /* doesn't return */
57 set_thread_flag(TIF_POLLING_NRFLAG);
59 tick_nohz_idle_enter();
60 while (!need_resched() && !cpu_should_die()) {
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.
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())
79 start_critical_timings();
82 set_thread_flag(TIF_POLLING_NRFLAG);
86 * Go into low thread priority and possibly
96 tick_nohz_idle_exit();
97 preempt_enable_no_resched();
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),
117 .proc_handler = proc_dointvec,
121 static ctl_table powersave_nap_sysctl_root[] = {
123 .procname = "kernel",
125 .child = powersave_nap_ctl_table,
131 register_powersave_nap_sysctl(void)
133 register_sysctl_table(powersave_nap_sysctl_root);
137 __initcall(register_powersave_nap_sysctl);