81 lines
2.8 KiB
C
81 lines
2.8 KiB
C
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/*
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* Scheduler code and data structures related to cpufreq.
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*
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* Copyright (C) 2016, Intel Corporation
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* Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/cpufreq.h>
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#include "sched.h"
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DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
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/**
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* cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
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* @cpu: The CPU to set the pointer for.
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* @data: New pointer value.
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* @func: Callback function to set for the CPU.
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*
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* Set and publish the update_util_data pointer for the given CPU.
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*
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* The update_util_data pointer of @cpu is set to @data and the callback
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* function pointer in the target struct update_util_data is set to @func.
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* That function will be called by cpufreq_update_util() from RCU-sched
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* read-side critical sections, so it must not sleep. @data will always be
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* passed to it as the first argument which allows the function to get to the
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* target update_util_data structure and its container.
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*
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* The update_util_data pointer of @cpu must be NULL when this function is
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* called or it will WARN() and return with no effect.
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*/
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void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
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void (*func)(struct update_util_data *data, u64 time,
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unsigned int flags))
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{
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if (WARN_ON(!data || !func))
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return;
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if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
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return;
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data->func = func;
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rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
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}
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EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
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/**
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* cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
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* @cpu: The CPU to clear the pointer for.
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*
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* Clear the update_util_data pointer for the given CPU.
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*
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* Callers must use RCU-sched callbacks to free any memory that might be
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* accessed via the old update_util_data pointer or invoke synchronize_sched()
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* right after this function to avoid use-after-free.
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*/
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void cpufreq_remove_update_util_hook(int cpu)
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{
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rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
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}
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EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
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/**
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* cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
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* @policy: cpufreq policy to check.
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*
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* Return 'true' if:
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* - the local and remote CPUs share @policy,
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* - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going
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* offline (in which case it is not expected to run cpufreq updates any more).
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*/
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bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
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{
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return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
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(policy->dvfs_possible_from_any_cpu &&
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rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));
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}
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