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779 lines
18 KiB
779 lines
18 KiB
/* |
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* cpuidle.c - core cpuidle infrastructure |
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* |
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* (C) 2006-2007 Venkatesh Pallipadi <[email protected]> |
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* Shaohua Li <[email protected]> |
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* Adam Belay <[email protected]> |
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* |
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* This code is licenced under the GPL. |
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*/ |
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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 <linux/mmu_context.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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u64 max_latency_ns, |
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unsigned int forbidden_flags, |
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bool s2idle) |
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{ |
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u64 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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if (dev->states_usage[i].disable || |
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s->exit_latency_ns <= latency_req || |
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s->exit_latency_ns > max_latency_ns || |
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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_ns; |
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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/unset governor override mode. |
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* @latency_limit_ns: Idle state exit latency limit (or no override if 0). |
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* |
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* If @latency_limit_ns is nonzero, set the current CPU to use the deepest idle |
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* state with exit latency within @latency_limit_ns (override governors going |
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* forward), or do not override governors if it is zero. |
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*/ |
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void cpuidle_use_deepest_state(u64 latency_limit_ns) |
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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->forced_idle_latency_limit_ns = latency_limit_ns; |
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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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* @latency_limit_ns: Idle state exit latency limit |
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* |
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* Return: the index of the deepest available idle state. |
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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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u64 latency_limit_ns) |
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{ |
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return find_deepest_state(drv, dev, latency_limit_ns, 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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ktime_t time_start, time_end; |
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struct cpuidle_state *target_state = &drv->states[index]; |
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time_start = ns_to_ktime(local_clock()); |
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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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if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) |
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rcu_idle_enter(); |
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target_state->enter_s2idle(dev, drv, index); |
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if (WARN_ON_ONCE(!irqs_disabled())) |
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local_irq_disable(); |
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if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) |
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rcu_idle_exit(); |
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tick_unfreeze(); |
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start_critical_timings(); |
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time_end = ns_to_ktime(local_clock()); |
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dev->states_usage[index].s2idle_time += ktime_us_delta(time_end, time_start); |
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dev->states_usage[index].s2idle_usage++; |
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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, U64_MAX, 0, true); |
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if (index > 0) { |
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enter_s2idle_proper(drv, dev, index); |
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local_irq_enable(); |
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} |
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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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/* |
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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_ns, |
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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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if (target_state->flags & CPUIDLE_FLAG_TLB_FLUSHED) |
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leave_mm(dev->cpu); |
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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(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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if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) |
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rcu_idle_enter(); |
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entered_state = target_state->enter(dev, drv, index); |
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if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) |
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rcu_idle_exit(); |
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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(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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if (entered_state >= 0) { |
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s64 diff, delay = drv->states[entered_state].exit_latency_ns; |
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int i; |
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/* |
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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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diff = ktime_sub(time_end, time_start); |
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dev->last_residency_ns = diff; |
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dev->states_usage[entered_state].time_ns += diff; |
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dev->states_usage[entered_state].usage++; |
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if (diff < drv->states[entered_state].target_residency_ns) { |
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for (i = entered_state - 1; i >= 0; i--) { |
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if (dev->states_usage[i].disable) |
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continue; |
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/* Shallower states are enabled, so update. */ |
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dev->states_usage[entered_state].above++; |
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break; |
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} |
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} else if (diff > delay) { |
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for (i = entered_state + 1; i < drv->state_count; i++) { |
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if (dev->states_usage[i].disable) |
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continue; |
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/* |
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* Update if a deeper state would have been a |
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* better match for the observed idle duration. |
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*/ |
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if (diff - delay >= drv->states[i].target_residency_ns) |
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dev->states_usage[entered_state].below++; |
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break; |
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} |
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} |
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} else { |
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dev->last_residency_ns = 0; |
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dev->states_usage[index].rejected++; |
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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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* @stop_tick: indication on whether or not to stop the tick |
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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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* The memory location pointed to by @stop_tick is expected to be written the |
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* 'false' boolean value if the scheduler tick should not be stopped before |
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* entering the returned state. |
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*/ |
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int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, |
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bool *stop_tick) |
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{ |
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return cpuidle_curr_governor->select(drv, dev, stop_tick); |
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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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int ret = 0; |
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/* |
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* Store the next hrtimer, which becomes either next tick or the next |
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* timer event, whatever expires first. Additionally, to make this data |
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* useful for consumers outside cpuidle, we rely on that the governor's |
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* ->select() callback have decided, whether to stop the tick or not. |
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*/ |
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WRITE_ONCE(dev->next_hrtimer, tick_nohz_get_next_hrtimer()); |
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if (cpuidle_state_is_coupled(drv, index)) |
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ret = cpuidle_enter_state_coupled(dev, drv, index); |
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else |
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ret = cpuidle_enter_state(dev, drv, index); |
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WRITE_ONCE(dev->next_hrtimer, 0); |
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return ret; |
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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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* Min polling interval of 10usec is a guess. It is assuming that |
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* for most users, the time for a single ping-pong workload like |
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* perf bench pipe would generally complete within 10usec but |
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* this is hardware dependant. Actual time can be estimated with |
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* |
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* perf bench sched pipe -l 10000 |
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* |
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* Run multiple times to avoid cpufreq effects. |
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*/ |
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#define CPUIDLE_POLL_MIN 10000 |
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#define CPUIDLE_POLL_MAX (TICK_NSEC / 16) |
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/** |
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* cpuidle_poll_time - return amount of time to poll for, |
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* governors can override dev->poll_limit_ns if necessary |
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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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* |
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*/ |
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u64 cpuidle_poll_time(struct cpuidle_driver *drv, |
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struct cpuidle_device *dev) |
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{ |
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int i; |
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u64 limit_ns; |
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BUILD_BUG_ON(CPUIDLE_POLL_MIN > CPUIDLE_POLL_MAX); |
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if (dev->poll_limit_ns) |
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return dev->poll_limit_ns; |
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limit_ns = CPUIDLE_POLL_MAX; |
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for (i = 1; i < drv->state_count; i++) { |
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u64 state_limit; |
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if (dev->states_usage[i].disable) |
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continue; |
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state_limit = drv->states[i].target_residency_ns; |
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if (state_limit < CPUIDLE_POLL_MIN) |
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continue; |
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limit_ns = min_t(u64, state_limit, CPUIDLE_POLL_MAX); |
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break; |
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} |
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dev->poll_limit_ns = limit_ns; |
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return dev->poll_limit_ns; |
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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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|
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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_ns = 0; |
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dev->next_hrtimer = 0; |
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} |
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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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struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
|
int i, ret; |
|
|
|
if (!try_module_get(drv->owner)) |
|
return -EINVAL; |
|
|
|
for (i = 0; i < drv->state_count; i++) { |
|
if (drv->states[i].flags & CPUIDLE_FLAG_UNUSABLE) |
|
dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER; |
|
|
|
if (drv->states[i].flags & CPUIDLE_FLAG_OFF) |
|
dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_USER; |
|
} |
|
|
|
per_cpu(cpuidle_devices, dev->cpu) = dev; |
|
list_add(&dev->device_list, &cpuidle_detected_devices); |
|
|
|
ret = cpuidle_coupled_register_device(dev); |
|
if (ret) |
|
__cpuidle_unregister_device(dev); |
|
else |
|
dev->registered = 1; |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cpuidle_register_device - registers a CPU's idle PM feature |
|
* @dev: the cpu |
|
*/ |
|
int cpuidle_register_device(struct cpuidle_device *dev) |
|
{ |
|
int ret = -EBUSY; |
|
|
|
if (!dev) |
|
return -EINVAL; |
|
|
|
mutex_lock(&cpuidle_lock); |
|
|
|
if (dev->registered) |
|
goto out_unlock; |
|
|
|
__cpuidle_device_init(dev); |
|
|
|
ret = __cpuidle_register_device(dev); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
ret = cpuidle_add_sysfs(dev); |
|
if (ret) |
|
goto out_unregister; |
|
|
|
ret = cpuidle_enable_device(dev); |
|
if (ret) |
|
goto out_sysfs; |
|
|
|
cpuidle_install_idle_handler(); |
|
|
|
out_unlock: |
|
mutex_unlock(&cpuidle_lock); |
|
|
|
return ret; |
|
|
|
out_sysfs: |
|
cpuidle_remove_sysfs(dev); |
|
out_unregister: |
|
__cpuidle_unregister_device(dev); |
|
goto out_unlock; |
|
} |
|
|
|
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); |
|
|
|
/** |
|
* cpuidle_init - core initializer |
|
*/ |
|
static int __init cpuidle_init(void) |
|
{ |
|
if (cpuidle_disabled()) |
|
return -ENODEV; |
|
|
|
return cpuidle_add_interface(cpu_subsys.dev_root); |
|
} |
|
|
|
module_param(off, int, 0444); |
|
module_param_string(governor, param_governor, CPUIDLE_NAME_LEN, 0444); |
|
core_initcall(cpuidle_init);
|
|
|