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![Gaurav Jindal](/assets/img/avatar_default.png)
Clean up cpuidle_enable_device() to avoid doing an assignment in an expression evaluated as an argument of if (), which also makes the code in question more readable. Signed-off-by: Gaurav Jindal <gauravjindal1104@gmail.com> [ rjw: Subject & changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
690 lines
16 KiB
C
690 lines
16 KiB
C
/*
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* cpuidle.c - core cpuidle infrastructure
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*
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* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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* Shaohua Li <shaohua.li@intel.com>
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* Adam Belay <abelay@novell.com>
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*
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* This code is licenced under the GPL.
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*/
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#include <linux/clockchips.h>
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/sched.h>
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#include <linux/sched/clock.h>
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#include <linux/notifier.h>
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#include <linux/pm_qos.h>
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#include <linux/cpu.h>
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#include <linux/cpuidle.h>
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#include <linux/ktime.h>
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#include <linux/hrtimer.h>
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#include <linux/module.h>
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#include <linux/suspend.h>
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#include <linux/tick.h>
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#include <trace/events/power.h>
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#include "cpuidle.h"
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DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
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DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
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DEFINE_MUTEX(cpuidle_lock);
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LIST_HEAD(cpuidle_detected_devices);
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static int enabled_devices;
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static int off __read_mostly;
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static int initialized __read_mostly;
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int cpuidle_disabled(void)
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{
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return off;
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}
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void disable_cpuidle(void)
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{
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off = 1;
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}
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bool cpuidle_not_available(struct cpuidle_driver *drv,
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struct cpuidle_device *dev)
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{
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return off || !initialized || !drv || !dev || !dev->enabled;
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}
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/**
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* cpuidle_play_dead - cpu off-lining
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*
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* Returns in case of an error or no driver
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*/
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int cpuidle_play_dead(void)
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{
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struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
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struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
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int i;
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if (!drv)
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return -ENODEV;
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/* Find lowest-power state that supports long-term idle */
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for (i = drv->state_count - 1; i >= 0; i--)
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if (drv->states[i].enter_dead)
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return drv->states[i].enter_dead(dev, i);
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return -ENODEV;
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}
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static int find_deepest_state(struct cpuidle_driver *drv,
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struct cpuidle_device *dev,
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unsigned int max_latency,
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unsigned int forbidden_flags,
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bool s2idle)
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{
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unsigned int latency_req = 0;
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int i, ret = 0;
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for (i = 1; i < drv->state_count; i++) {
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struct cpuidle_state *s = &drv->states[i];
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struct cpuidle_state_usage *su = &dev->states_usage[i];
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if (s->disabled || su->disable || s->exit_latency <= latency_req
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|| s->exit_latency > max_latency
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|| (s->flags & forbidden_flags)
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|| (s2idle && !s->enter_s2idle))
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continue;
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latency_req = s->exit_latency;
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ret = i;
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}
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return ret;
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}
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/**
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* cpuidle_use_deepest_state - Set/clear governor override flag.
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* @enable: New value of the flag.
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*
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* Set/unset the current CPU to use the deepest idle state (override governors
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* going forward if set).
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*/
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void cpuidle_use_deepest_state(bool enable)
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{
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struct cpuidle_device *dev;
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preempt_disable();
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dev = cpuidle_get_device();
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if (dev)
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dev->use_deepest_state = enable;
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preempt_enable();
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}
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/**
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* cpuidle_find_deepest_state - Find the deepest available idle state.
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* @drv: cpuidle driver for the given CPU.
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* @dev: cpuidle device for the given CPU.
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*/
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int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
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struct cpuidle_device *dev)
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{
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return find_deepest_state(drv, dev, UINT_MAX, 0, false);
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}
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#ifdef CONFIG_SUSPEND
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static void enter_s2idle_proper(struct cpuidle_driver *drv,
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struct cpuidle_device *dev, int index)
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{
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/*
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* trace_suspend_resume() called by tick_freeze() for the last CPU
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* executing it contains RCU usage regarded as invalid in the idle
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* context, so tell RCU about that.
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*/
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RCU_NONIDLE(tick_freeze());
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/*
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* The state used here cannot be a "coupled" one, because the "coupled"
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* cpuidle mechanism enables interrupts and doing that with timekeeping
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* suspended is generally unsafe.
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*/
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stop_critical_timings();
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drv->states[index].enter_s2idle(dev, drv, index);
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WARN_ON(!irqs_disabled());
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/*
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* timekeeping_resume() that will be called by tick_unfreeze() for the
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* first CPU executing it calls functions containing RCU read-side
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* critical sections, so tell RCU about that.
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*/
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RCU_NONIDLE(tick_unfreeze());
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start_critical_timings();
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}
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/**
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* cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
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* @drv: cpuidle driver for the given CPU.
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* @dev: cpuidle device for the given CPU.
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*
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* If there are states with the ->enter_s2idle callback, find the deepest of
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* them and enter it with frozen tick.
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*/
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int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev)
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{
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int index;
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/*
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* Find the deepest state with ->enter_s2idle present, which guarantees
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* that interrupts won't be enabled when it exits and allows the tick to
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* be frozen safely.
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*/
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index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
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if (index > 0)
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enter_s2idle_proper(drv, dev, index);
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return index;
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}
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#endif /* CONFIG_SUSPEND */
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/**
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* cpuidle_enter_state - enter the state and update stats
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* @dev: cpuidle device for this cpu
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* @drv: cpuidle driver for this cpu
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* @index: index into the states table in @drv of the state to enter
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*/
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int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
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int index)
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{
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int entered_state;
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struct cpuidle_state *target_state = &drv->states[index];
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bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
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ktime_t time_start, time_end;
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s64 diff;
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/*
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* Tell the time framework to switch to a broadcast timer because our
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* local timer will be shut down. If a local timer is used from another
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* CPU as a broadcast timer, this call may fail if it is not available.
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*/
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if (broadcast && tick_broadcast_enter()) {
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index = find_deepest_state(drv, dev, target_state->exit_latency,
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CPUIDLE_FLAG_TIMER_STOP, false);
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if (index < 0) {
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default_idle_call();
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return -EBUSY;
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}
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target_state = &drv->states[index];
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broadcast = false;
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}
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/* Take note of the planned idle state. */
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sched_idle_set_state(target_state);
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trace_cpu_idle_rcuidle(index, dev->cpu);
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time_start = ns_to_ktime(local_clock());
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stop_critical_timings();
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entered_state = target_state->enter(dev, drv, index);
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start_critical_timings();
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sched_clock_idle_wakeup_event();
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time_end = ns_to_ktime(local_clock());
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trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
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/* The cpu is no longer idle or about to enter idle. */
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sched_idle_set_state(NULL);
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if (broadcast) {
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if (WARN_ON_ONCE(!irqs_disabled()))
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local_irq_disable();
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tick_broadcast_exit();
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}
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if (!cpuidle_state_is_coupled(drv, index))
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local_irq_enable();
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diff = ktime_us_delta(time_end, time_start);
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if (diff > INT_MAX)
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diff = INT_MAX;
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dev->last_residency = (int) diff;
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if (entered_state >= 0) {
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/* Update cpuidle counters */
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/* This can be moved to within driver enter routine
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* but that results in multiple copies of same code.
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*/
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dev->states_usage[entered_state].time += dev->last_residency;
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dev->states_usage[entered_state].usage++;
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} else {
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dev->last_residency = 0;
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}
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return entered_state;
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}
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/**
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* cpuidle_select - ask the cpuidle framework to choose an idle state
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*
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* @drv: the cpuidle driver
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* @dev: the cpuidle device
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*
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* Returns the index of the idle state. The return value must not be negative.
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*/
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int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
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{
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return cpuidle_curr_governor->select(drv, dev);
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}
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/**
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* cpuidle_enter - enter into the specified idle state
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*
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* @drv: the cpuidle driver tied with the cpu
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* @dev: the cpuidle device
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* @index: the index in the idle state table
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*
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* Returns the index in the idle state, < 0 in case of error.
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* The error code depends on the backend driver
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*/
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int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
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int index)
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{
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if (cpuidle_state_is_coupled(drv, index))
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return cpuidle_enter_state_coupled(dev, drv, index);
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return cpuidle_enter_state(dev, drv, index);
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}
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/**
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* cpuidle_reflect - tell the underlying governor what was the state
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* we were in
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*
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* @dev : the cpuidle device
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* @index: the index in the idle state table
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*
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*/
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void cpuidle_reflect(struct cpuidle_device *dev, int index)
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{
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if (cpuidle_curr_governor->reflect && index >= 0)
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cpuidle_curr_governor->reflect(dev, index);
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}
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/**
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* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
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*/
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void cpuidle_install_idle_handler(void)
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{
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if (enabled_devices) {
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/* Make sure all changes finished before we switch to new idle */
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smp_wmb();
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initialized = 1;
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}
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}
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/**
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* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
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*/
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void cpuidle_uninstall_idle_handler(void)
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{
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if (enabled_devices) {
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initialized = 0;
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wake_up_all_idle_cpus();
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}
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/*
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* Make sure external observers (such as the scheduler)
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* are done looking at pointed idle states.
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*/
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synchronize_rcu();
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}
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/**
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* cpuidle_pause_and_lock - temporarily disables CPUIDLE
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*/
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void cpuidle_pause_and_lock(void)
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{
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mutex_lock(&cpuidle_lock);
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cpuidle_uninstall_idle_handler();
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}
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EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
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/**
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* cpuidle_resume_and_unlock - resumes CPUIDLE operation
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*/
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void cpuidle_resume_and_unlock(void)
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{
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cpuidle_install_idle_handler();
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mutex_unlock(&cpuidle_lock);
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}
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EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
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/* Currently used in suspend/resume path to suspend cpuidle */
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void cpuidle_pause(void)
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{
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mutex_lock(&cpuidle_lock);
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cpuidle_uninstall_idle_handler();
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mutex_unlock(&cpuidle_lock);
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}
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/* Currently used in suspend/resume path to resume cpuidle */
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void cpuidle_resume(void)
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{
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mutex_lock(&cpuidle_lock);
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cpuidle_install_idle_handler();
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mutex_unlock(&cpuidle_lock);
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}
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/**
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* cpuidle_enable_device - enables idle PM for a CPU
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* @dev: the CPU
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*
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* This function must be called between cpuidle_pause_and_lock and
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* cpuidle_resume_and_unlock when used externally.
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*/
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int cpuidle_enable_device(struct cpuidle_device *dev)
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{
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int ret;
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struct cpuidle_driver *drv;
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if (!dev)
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return -EINVAL;
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if (dev->enabled)
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return 0;
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if (!cpuidle_curr_governor)
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return -EIO;
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drv = cpuidle_get_cpu_driver(dev);
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if (!drv)
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return -EIO;
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if (!dev->registered)
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return -EINVAL;
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ret = cpuidle_add_device_sysfs(dev);
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if (ret)
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return ret;
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if (cpuidle_curr_governor->enable) {
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ret = cpuidle_curr_governor->enable(drv, dev);
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if (ret)
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goto fail_sysfs;
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}
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smp_wmb();
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dev->enabled = 1;
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enabled_devices++;
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return 0;
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fail_sysfs:
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cpuidle_remove_device_sysfs(dev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpuidle_enable_device);
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/**
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* cpuidle_disable_device - disables idle PM for a CPU
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* @dev: the CPU
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*
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* This function must be called between cpuidle_pause_and_lock and
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* cpuidle_resume_and_unlock when used externally.
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*/
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void cpuidle_disable_device(struct cpuidle_device *dev)
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{
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struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
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if (!dev || !dev->enabled)
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return;
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if (!drv || !cpuidle_curr_governor)
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return;
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dev->enabled = 0;
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if (cpuidle_curr_governor->disable)
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cpuidle_curr_governor->disable(drv, dev);
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cpuidle_remove_device_sysfs(dev);
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enabled_devices--;
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}
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EXPORT_SYMBOL_GPL(cpuidle_disable_device);
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static void __cpuidle_unregister_device(struct cpuidle_device *dev)
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{
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struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
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list_del(&dev->device_list);
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per_cpu(cpuidle_devices, dev->cpu) = NULL;
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module_put(drv->owner);
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dev->registered = 0;
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}
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static void __cpuidle_device_init(struct cpuidle_device *dev)
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{
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memset(dev->states_usage, 0, sizeof(dev->states_usage));
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dev->last_residency = 0;
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}
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/**
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* __cpuidle_register_device - internal register function called before register
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* and enable routines
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* @dev: the cpu
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*
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* cpuidle_lock mutex must be held before this is called
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*/
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static int __cpuidle_register_device(struct cpuidle_device *dev)
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{
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int ret;
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struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
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if (!try_module_get(drv->owner))
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return -EINVAL;
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per_cpu(cpuidle_devices, dev->cpu) = dev;
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list_add(&dev->device_list, &cpuidle_detected_devices);
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ret = cpuidle_coupled_register_device(dev);
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if (ret)
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__cpuidle_unregister_device(dev);
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else
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dev->registered = 1;
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return ret;
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}
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/**
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* cpuidle_register_device - registers a CPU's idle PM feature
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* @dev: the cpu
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*/
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int cpuidle_register_device(struct cpuidle_device *dev)
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{
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int ret = -EBUSY;
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if (!dev)
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return -EINVAL;
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mutex_lock(&cpuidle_lock);
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if (dev->registered)
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goto out_unlock;
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__cpuidle_device_init(dev);
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ret = __cpuidle_register_device(dev);
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if (ret)
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goto out_unlock;
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ret = cpuidle_add_sysfs(dev);
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if (ret)
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goto out_unregister;
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ret = cpuidle_enable_device(dev);
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if (ret)
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goto out_sysfs;
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cpuidle_install_idle_handler();
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out_unlock:
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mutex_unlock(&cpuidle_lock);
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return ret;
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out_sysfs:
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cpuidle_remove_sysfs(dev);
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out_unregister:
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__cpuidle_unregister_device(dev);
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goto out_unlock;
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}
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|
|
EXPORT_SYMBOL_GPL(cpuidle_register_device);
|
|
|
|
/**
|
|
* cpuidle_unregister_device - unregisters a CPU's idle PM feature
|
|
* @dev: the cpu
|
|
*/
|
|
void cpuidle_unregister_device(struct cpuidle_device *dev)
|
|
{
|
|
if (!dev || dev->registered == 0)
|
|
return;
|
|
|
|
cpuidle_pause_and_lock();
|
|
|
|
cpuidle_disable_device(dev);
|
|
|
|
cpuidle_remove_sysfs(dev);
|
|
|
|
__cpuidle_unregister_device(dev);
|
|
|
|
cpuidle_coupled_unregister_device(dev);
|
|
|
|
cpuidle_resume_and_unlock();
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
|
|
|
|
/**
|
|
* cpuidle_unregister: unregister a driver and the devices. This function
|
|
* can be used only if the driver has been previously registered through
|
|
* the cpuidle_register function.
|
|
*
|
|
* @drv: a valid pointer to a struct cpuidle_driver
|
|
*/
|
|
void cpuidle_unregister(struct cpuidle_driver *drv)
|
|
{
|
|
int cpu;
|
|
struct cpuidle_device *device;
|
|
|
|
for_each_cpu(cpu, drv->cpumask) {
|
|
device = &per_cpu(cpuidle_dev, cpu);
|
|
cpuidle_unregister_device(device);
|
|
}
|
|
|
|
cpuidle_unregister_driver(drv);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpuidle_unregister);
|
|
|
|
/**
|
|
* cpuidle_register: registers the driver and the cpu devices with the
|
|
* coupled_cpus passed as parameter. This function is used for all common
|
|
* initialization pattern there are in the arch specific drivers. The
|
|
* devices is globally defined in this file.
|
|
*
|
|
* @drv : a valid pointer to a struct cpuidle_driver
|
|
* @coupled_cpus: a cpumask for the coupled states
|
|
*
|
|
* Returns 0 on success, < 0 otherwise
|
|
*/
|
|
int cpuidle_register(struct cpuidle_driver *drv,
|
|
const struct cpumask *const coupled_cpus)
|
|
{
|
|
int ret, cpu;
|
|
struct cpuidle_device *device;
|
|
|
|
ret = cpuidle_register_driver(drv);
|
|
if (ret) {
|
|
pr_err("failed to register cpuidle driver\n");
|
|
return ret;
|
|
}
|
|
|
|
for_each_cpu(cpu, drv->cpumask) {
|
|
device = &per_cpu(cpuidle_dev, cpu);
|
|
device->cpu = cpu;
|
|
|
|
#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
|
|
/*
|
|
* On multiplatform for ARM, the coupled idle states could be
|
|
* enabled in the kernel even if the cpuidle driver does not
|
|
* use it. Note, coupled_cpus is a struct copy.
|
|
*/
|
|
if (coupled_cpus)
|
|
device->coupled_cpus = *coupled_cpus;
|
|
#endif
|
|
ret = cpuidle_register_device(device);
|
|
if (!ret)
|
|
continue;
|
|
|
|
pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
|
|
|
|
cpuidle_unregister(drv);
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpuidle_register);
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/*
|
|
* This function gets called when a part of the kernel has a new latency
|
|
* requirement. This means we need to get all processors out of their C-state,
|
|
* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
|
|
* wakes them all right up.
|
|
*/
|
|
static int cpuidle_latency_notify(struct notifier_block *b,
|
|
unsigned long l, void *v)
|
|
{
|
|
wake_up_all_idle_cpus();
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block cpuidle_latency_notifier = {
|
|
.notifier_call = cpuidle_latency_notify,
|
|
};
|
|
|
|
static inline void latency_notifier_init(struct notifier_block *n)
|
|
{
|
|
pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
|
|
}
|
|
|
|
#else /* CONFIG_SMP */
|
|
|
|
#define latency_notifier_init(x) do { } while (0)
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/**
|
|
* cpuidle_init - core initializer
|
|
*/
|
|
static int __init cpuidle_init(void)
|
|
{
|
|
int ret;
|
|
|
|
if (cpuidle_disabled())
|
|
return -ENODEV;
|
|
|
|
ret = cpuidle_add_interface(cpu_subsys.dev_root);
|
|
if (ret)
|
|
return ret;
|
|
|
|
latency_notifier_init(&cpuidle_latency_notifier);
|
|
|
|
return 0;
|
|
}
|
|
|
|
module_param(off, int, 0444);
|
|
core_initcall(cpuidle_init);
|