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/*
* cpuidle.c - core cpuidle infrastructure
*
* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
* Shaohua Li <shaohua.li@intel.com>
* Adam Belay <abelay@novell.com>
*
* This code is licenced under the GPL.
*/
#include <linux/clockchips.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/notifier.h>
#include <linux/pm_qos.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>
#include <linux/hrtimer.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/tick.h>
#include <trace/events/power.h>
#include "cpuidle.h"
DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);
static int enabled_devices;
static int off __read_mostly;
static int initialized __read_mostly;
int cpuidle_disabled(void)
{
return off;
}
void disable_cpuidle(void)
{
off = 1;
}
bool cpuidle_not_available(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
return off || !initialized || !drv || !dev || !dev->enabled;
}
/**
* cpuidle_play_dead - cpu off-lining
*
* Returns in case of an error or no driver
*/
int cpuidle_play_dead(void)
{
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
int i;
if (!drv)
return -ENODEV;
/* Find lowest-power state that supports long-term idle */
for (i = drv->state_count - 1; i >= 0; i--)
if (drv->states[i].enter_dead)
return drv->states[i].enter_dead(dev, i);
return -ENODEV;
}
static int find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev,
unsigned int max_latency,
unsigned int forbidden_flags,
bool freeze)
{
unsigned int latency_req = 0;
int i, ret = 0;
for (i = 1; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
struct cpuidle_state_usage *su = &dev->states_usage[i];
if (s->disabled || su->disable || s->exit_latency <= latency_req
|| s->exit_latency > max_latency
|| (s->flags & forbidden_flags)
|| (freeze && !s->enter_freeze))
continue;
latency_req = s->exit_latency;
ret = i;
}
return ret;
}
/**
* cpuidle_use_deepest_state - Set/clear governor override flag.
* @enable: New value of the flag.
*
* Set/unset the current CPU to use the deepest idle state (override governors
* going forward if set).
*/
void cpuidle_use_deepest_state(bool enable)
{
struct cpuidle_device *dev;
preempt_disable();
dev = cpuidle_get_device();
if (dev)
dev->use_deepest_state = enable;
preempt_enable();
}
/**
* cpuidle_find_deepest_state - Find the deepest available idle state.
* @drv: cpuidle driver for the given CPU.
* @dev: cpuidle device for the given CPU.
*/
int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
return find_deepest_state(drv, dev, UINT_MAX, 0, false);
}
#ifdef CONFIG_SUSPEND
static void enter_freeze_proper(struct cpuidle_driver *drv,
struct cpuidle_device *dev, int index)
{
/*
* trace_suspend_resume() called by tick_freeze() for the last CPU
* executing it contains RCU usage regarded as invalid in the idle
* context, so tell RCU about that.
*/
RCU_NONIDLE(tick_freeze());
/*
* The state used here cannot be a "coupled" one, because the "coupled"
* cpuidle mechanism enables interrupts and doing that with timekeeping
* suspended is generally unsafe.
*/
stop_critical_timings();
drv->states[index].enter_freeze(dev, drv, index);
WARN_ON(!irqs_disabled());
/*
* timekeeping_resume() that will be called by tick_unfreeze() for the
* first CPU executing it calls functions containing RCU read-side
* critical sections, so tell RCU about that.
*/
RCU_NONIDLE(tick_unfreeze());
start_critical_timings();
}
/**
* cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
* @drv: cpuidle driver for the given CPU.
* @dev: cpuidle device for the given CPU.
*
* If there are states with the ->enter_freeze callback, find the deepest of
* them and enter it with frozen tick.
*/
int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
int index;
/*
* Find the deepest state with ->enter_freeze present, which guarantees
* that interrupts won't be enabled when it exits and allows the tick to
* be frozen safely.
*/
index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
if (index > 0)
enter_freeze_proper(drv, dev, index);
return index;
}
#endif /* CONFIG_SUSPEND */
/**
* cpuidle_enter_state - enter the state and update stats
* @dev: cpuidle device for this cpu
* @drv: cpuidle driver for this cpu
* @index: index into the states table in @drv of the state to enter
*/
int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
int index)
{
int entered_state;
struct cpuidle_state *target_state = &drv->states[index];
bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
ktime_t time_start, time_end;
s64 diff;
/*
* Tell the time framework to switch to a broadcast timer because our
* local timer will be shut down. If a local timer is used from another
* CPU as a broadcast timer, this call may fail if it is not available.
*/
if (broadcast && tick_broadcast_enter()) {
index = find_deepest_state(drv, dev, target_state->exit_latency,
CPUIDLE_FLAG_TIMER_STOP, false);
if (index < 0) {
default_idle_call();
return -EBUSY;
}
target_state = &drv->states[index];
}
/* Take note of the planned idle state. */
sched_idle_set_state(target_state);
trace_cpu_idle_rcuidle(index, dev->cpu);
time_start = ns_to_ktime(local_clock());
stop_critical_timings();
entered_state = target_state->enter(dev, drv, index);
start_critical_timings();
sched_clock_idle_wakeup_event();
time_end = ns_to_ktime(local_clock());
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
/* The cpu is no longer idle or about to enter idle. */
sched_idle_set_state(NULL);
if (broadcast) {
if (WARN_ON_ONCE(!irqs_disabled()))
local_irq_disable();
tick_broadcast_exit();
}
if (!cpuidle_state_is_coupled(drv, index))
local_irq_enable();
diff = ktime_us_delta(time_end, time_start);
if (diff > INT_MAX)
diff = INT_MAX;
dev->last_residency = (int) diff;
if (entered_state >= 0) {
/* Update cpuidle counters */
/* This can be moved to within driver enter routine
* but that results in multiple copies of same code.
*/
dev->states_usage[entered_state].time += dev->last_residency;
dev->states_usage[entered_state].usage++;
} else
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