/*
* 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)
*
* 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>
*
* 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/config.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/smp.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/time.h>
#include <asm/iSeries/HvCall.h>
#include <asm/iSeries/ItLpQueue.h>
#include <asm/plpar_wrappers.h>
#include <asm/systemcfg.h>
extern void power4_idle(void);
static int (*idle_loop)(void);
#ifdef CONFIG_PPC_ISERIES
static unsigned long maxYieldTime = 0;
static unsigned long minYieldTime = 0xffffffffffffffffUL;
static void yield_shared_processor(void)
{
unsigned long tb;
unsigned long yieldTime;
HvCall_setEnabledInterrupts(HvCall_MaskIPI |
HvCall_MaskLpEvent |
HvCall_MaskLpProd |
HvCall_MaskTimeout);
tb = get_tb();
/* Compute future tb value when yield should expire */
HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
yieldTime = get_tb() - tb;
if (yieldTime > maxYieldTime)
maxYieldTime = yieldTime;
if (yieldTime < minYieldTime)
minYieldTime = yieldTime;
/*
* The decrementer stops during the yield. Force a fake decrementer
* here and let the timer_interrupt code sort out the actual time.
*/
get_paca()->lppaca.int_dword.fields.decr_int = 1;
process_iSeries_events();
}
static int iSeries_idle(void)
{
struct paca_struct *lpaca;
long oldval;
unsigned long CTRL;
/* ensure iSeries run light will be out when idle */
clear_thread_flag(TIF_RUN_LIGHT);
CTRL = mfspr(CTRLF);
CTRL &= ~RUNLATCH;
mtspr(CTRLT, CTRL);
lpaca = get_paca();
while (1) {
if (lpaca->lppaca.shared_proc) {
if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
process_iSeries_events();
if (!need_resched())
yield_shared_processor();
} else {
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
if (!oldval) {
set_thread_flag(TIF_POLLING_NRFLAG);
while (!need_resched()) {
HMT_medium();
if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
process_iSeries_events();
HMT_low();
}
HMT_medium();
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
}
schedule();
}
return 0;
}
#else
static int default_idle(void)
{
long oldval;
unsigned int cpu = smp_processor_id();
while (1) {
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
if (!oldval) {
set_thread_flag(TIF_POLLING_NRFLAG);
while (!need_resched() && !cpu_is_offline(cpu)) {
barrier();
/*
* Go into low thread priority and possibly
* low power mode.
*/
HMT_low();
HMT_very_low();
}
HMT_medium();
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
schedule();
if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
cpu_die();
}
return 0;
}
#ifdef CONFIG_PPC_PSERIES
DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
int dedicated_idle(void)
{
long oldval;
struct paca_struct *lpaca = get_paca(), *ppaca;
unsigned long start_snooze;
unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
unsigned int cpu = smp_processor_id();
ppaca = &paca[cpu ^ 1];
while (1) {
/*
* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch.
*/
lpaca->lppaca.idle = 1;
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
if (!oldval) {
set_thread_flag(TIF_POLLING_NRFLAG);
start_snooze = __get_tb() +
*smt_snooze_delay * tb_ticks_per_usec;
while (!need_resched() && !cpu_is_offline(cpu)) {
/*
* Go into low thread priority and possibly
* low power mode.
*/
HMT_low();
HMT_very_low();
if (*smt_snooze_delay == 0 ||
__get_tb() < start_snooze)
continue;
HMT_medium();
if (!(ppaca->lppaca.idle)) {
local_irq_disable();
/*
* We are about to sleep the thread
* and so wont be polling any
* more.
*/
clear_thread_flag(TIF_POLLING_NRFLAG);
/*
* SMT dynamic mode. Cede will result
* in this thread going dormant, if the
* partner thread is still doing work.
* Thread wakes up if partner goes idle,
* an interrupt is presented, or a prod
* occurs. Returning from the cede
* enables external interrupts.
*/
if (!need_resched())
cede_processor();
else
local_irq_enable();
} else {
/*
* Give the HV an opportunity at the
* processor, since we are not doing
* any work.
*/
poll_pending();
}
}
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
HMT_medium();
lpaca->lppaca.idle = 0;
schedule();
if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
cpu_die();
}
return 0;
}
static int shared_idle(void)
{
struct paca_struct *lpaca = get_paca();
unsigned int cpu = smp_processor_id();
while (1) {
/*
* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch.
*/
lpaca->lppaca.idle = 1;
while (!need_resched() && !cpu_is_offline(cpu)) {
local_irq_disable();
/*
* Yield the processor to the hypervisor. We return if
* an external interrupt occurs (which are driven prior
* to returning here) or if a prod occurs from another
* processor. When returning here, external interrupts
* are enabled.
*
* Check need_resched() again with interrupts disabled
* to avoid a race.
*/
if (!need_resched())
cede_processor();
else
local_irq_enable();
}
HMT_medium();
lpaca->lppaca.idle = 0;
schedule();
if (cpu_is_offline(smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
cpu_die();
}
return 0;
}
#endif /* CONFIG_PPC_PSERIES */
static int native_idle(void)
{
while(1) {
/* check CPU type here */
if (!need_resched())
power4_idle();
if (need_resched())
schedule();
if (cpu_is_offline(_smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
cpu_die();
}
return 0;
}
#endif /* CONFIG_PPC_ISERIES */
void cpu_idle(void)
{
idle_loop();
}
int powersave_nap;
#ifdef CONFIG_SYSCTL
/*
* Register the sysctl to set/clear powersave_nap.
*/
static ctl_table powersave_nap_ctl_table[]={
{
.ctl_name = KERN_PPC_POWERSAVE_NAP,
.procname = "powersave-nap",
.data = &powersave_nap,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{ 0, },
};
static ctl_table powersave_nap_sysctl_root[] = {
{ 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
{ 0,},
};
static int __init
register_powersave_nap_sysctl(void)
{
register_sysctl_table(powersave_nap_sysctl_root, 0);
return 0;
}
__initcall(register_powersave_nap_sysctl);
#endif
int idle_setup(void)
{
/*
* Move that junk to each platform specific file, eventually define
* a pSeries_idle for shared processor stuff
*/
#ifdef CONFIG_PPC_ISERIES
idle_loop = iSeries_idle;
return 1;
#else
idle_loop = default_idle;
#endif
#ifdef CONFIG_PPC_PSERIES
if (systemcfg->platform & PLATFORM_PSERIES) {
if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
if (get_paca()->lppaca.shared_proc) {
printk(KERN_INFO "Using shared processor idle loop\n");
idle_loop = shared_idle;
} else {
printk(KERN_INFO "Using dedicated idle loop\n");
idle_loop = dedicated_idle;
}
} else {
printk(KERN_INFO "Using default idle loop\n");
idle_loop = default_idle;
}
}
#endif /* CONFIG_PPC_PSERIES */
#ifndef CONFIG_PPC_ISERIES
if (systemcfg->platform == PLATFORM_POWERMAC ||
systemcfg->platform == PLATFORM_MAPLE) {
printk(KERN_INFO "Using native/NAP idle loop\n");
idle_loop = native_idle;
}
#endif /* CONFIG_PPC_ISERIES */
return 1;
}
