2 * Scheduler code and data structures related to cpufreq.
4 * Copyright (C) 2016, Intel Corporation
5 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/cpufreq.h>
15 DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
18 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
19 * @cpu: The CPU to set the pointer for.
20 * @data: New pointer value.
21 * @func: Callback function to set for the CPU.
23 * Set and publish the update_util_data pointer for the given CPU.
25 * The update_util_data pointer of @cpu is set to @data and the callback
26 * function pointer in the target struct update_util_data is set to @func.
27 * That function will be called by cpufreq_update_util() from RCU-sched
28 * read-side critical sections, so it must not sleep. @data will always be
29 * passed to it as the first argument which allows the function to get to the
30 * target update_util_data structure and its container.
32 * The update_util_data pointer of @cpu must be NULL when this function is
33 * called or it will WARN() and return with no effect.
35 void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
36 void (*func)(struct update_util_data *data, u64 time,
39 if (WARN_ON(!data || !func))
42 if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
46 rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
48 EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
51 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
52 * @cpu: The CPU to clear the pointer for.
54 * Clear the update_util_data pointer for the given CPU.
56 * Callers must use RCU-sched callbacks to free any memory that might be
57 * accessed via the old update_util_data pointer or invoke synchronize_sched()
58 * right after this function to avoid use-after-free.
60 void cpufreq_remove_update_util_hook(int cpu)
62 rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
64 EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
67 * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
68 * @policy: cpufreq policy to check.
71 * - the local and remote CPUs share @policy,
72 * - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going
73 * offline (in which case it is not expected to run cpufreq updates any more).
75 bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
77 return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
78 (policy->dvfs_possible_from_any_cpu &&
79 rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));