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/*
* Idle daemon for PowerPC. Idle daemon will handle any action
* that needs to be taken when the system becomes idle.
*
* Originally written by Cort Dougan (cort@cs.nmt.edu).
* Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
* Paul Mackerras and others.
*
* iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
*
* Additional shared processor, SMT, and firmware support
* Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
*
* 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/sysctl.h>
#include <linux/tick.h>
#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/runlatch.h>
#include <asm/smp.h>
#ifdef CONFIG_HOTPLUG_CPU
#define cpu_should_die() cpu_is_offline(smp_processor_id())
#else
#define cpu_should_die() 0
#endif
unsigned long cpuidle_disable = IDLE_NO_OVERRIDE;
EXPORT_SYMBOL(cpuidle_disable);
static int __init powersave_off(char *arg)
{
ppc_md.power_save = NULL;
cpuidle_disable = IDLE_POWERSAVE_OFF;
return 0;
}
__setup("powersave=off", powersave_off);
/*
* The body of the idle task.
*/
void cpu_idle(void)
{
if (ppc_md.idle_loop)
ppc_md.idle_loop(); /* doesn't return */
set_thread_flag(TIF_POLLING_NRFLAG);
while (1) {
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched() && !cpu_should_die()) {
ppc64_runlatch_off();
if (ppc_md.power_save) {
clear_thread_flag(TIF_POLLING_NRFLAG);
/*
* smp_mb is so clearing of TIF_POLLING_NRFLAG
* is ordered w.r.t. need_resched() test.
*/
smp_mb();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
/* check again after disabling irqs */
if (!need_resched() && !cpu_should_die())
ppc_md.power_save();
start_critical_timings();
/* Some power_save functions return with
* interrupts enabled, some don't.
*/
if (irqs_disabled())
local_irq_enable();
set_thread_flag(TIF_POLLING_NRFLAG);
} else {
/*
* Go into low thread priority and possibly
* low power mode.
*/
HMT_low();
HMT_very_low();
}
}
HMT_medium();
ppc64_runlatch_on();
rcu_idle_exit();
tick_nohz_idle_exit();
if (cpu_should_die()) {
sched_preempt_enable_no_resched();
cpu_die();
}
schedule_preempt_disabled();
}
}
/*
* cpu_idle_wait - Used to ensure that all the CPUs come out of the old
* idle loop and start using the new idle loop.
* Required while changing idle handler on SMP systems.
* Caller must have changed idle handler to the new value before the call.
* This window may be larger on shared systems.
*/
void cpu_idle_wait(void)
{
int cpu;
smp_mb();
/* kick all the CPUs so that they exit out of old idle routine */
get_online_cpus();
for_each_online_cpu(cpu) {
if (cpu != smp_processor_id())
smp_send_reschedule(cpu);
}
put_online_cpus();
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
int powersave_nap;
#ifdef CONFIG_SYSCTL
/*
* Register the sysctl to set/clear powersave_nap.
*/
static ctl_table powersave_nap_ctl_table[]={
{
.procname = "powersave-nap",
.data = &powersave_nap,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{}
};
static ctl_table powersave_nap_sysctl_root[] = {
{
.procname = "kernel",
.mode = 0555,
.child = powersave_nap_ctl_table,
},
{}
};
static int __init
register_powersave_nap_sysctl(void)
{
register_sysctl_table(powersave_nap_sysctl_root);
return 0;
}
__initcall(register_powersave_nap_sysctl);
#endif
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