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/* this is used for software suspend, and that shuts down
37 * CPUs even while the system is still booting... */
38#define cpu_should_die()	(cpu_is_offline(smp_processor_id()) && \
39				   (system_state == SYSTEM_RUNNING     \
40				 || system_state == SYSTEM_BOOTING))
41#else
42#define cpu_should_die()	0
43#endif
44
45static int __init powersave_off(char *arg)
46{
47	ppc_md.power_save = NULL;
48	return 0;
49}
50__setup("powersave=off", powersave_off);
51
52/*
53 * The body of the idle task.
54 */
55void cpu_idle(void)
56{
57	if (ppc_md.idle_loop)
58		ppc_md.idle_loop();	/* doesn't return */
59
60	set_thread_flag(TIF_POLLING_NRFLAG);
61	while (1) {
62		while (!need_resched() && !cpu_should_die()) {
63			ppc64_runlatch_off();
64
65			if (ppc_md.power_save) {
66				clear_thread_flag(TIF_POLLING_NRFLAG);
67				/*
68				 * smp_mb is so clearing of TIF_POLLING_NRFLAG
69				 * is ordered w.r.t. need_resched() test.
70				 */
71				smp_mb();
72				local_irq_disable();
73
74				/* check again after disabling irqs */
75				if (!need_resched() && !cpu_should_die())
76					ppc_md.power_save();
77
78				local_irq_enable();
79				set_thread_flag(TIF_POLLING_NRFLAG);
80
81			} else {
82				/*
83				 * Go into low thread priority and possibly
84				 * low power mode.
85				 */
86				HMT_low();
87				HMT_very_low();
88			}
89		}
90
91		HMT_medium();
92		ppc64_runlatch_on();
93		if (cpu_should_die())
94			cpu_die();
95		preempt_enable_no_resched();
96		schedule();
97		preempt_disable();
98	}
99}
100
101int powersave_nap;
102
103#ifdef CONFIG_SYSCTL
104/*
105 * Register the sysctl to set/clear powersave_nap.
106 */
107static ctl_table powersave_nap_ctl_table[]={
108	{
109		.ctl_name	= KERN_PPC_POWERSAVE_NAP,
110		.procname	= "powersave-nap",
111		.data		= &powersave_nap,
112		.maxlen		= sizeof(int),
113		.mode		= 0644,
114		.proc_handler	= &proc_dointvec,
115	},
116	{}
117};
118static ctl_table powersave_nap_sysctl_root[] = {
119	{
120		.ctl_name	= CTL_KERN,
121		.procname	= "kernel",
122		.mode		= 0755,
123		.child		= powersave_nap_ctl_table,
124	},
125	{}
126};
127
128static int __init
129register_powersave_nap_sysctl(void)
130{
131	register_sysctl_table(powersave_nap_sysctl_root);
132
133	return 0;
134}
135__initcall(register_powersave_nap_sysctl);
136#endif
137