135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
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/*
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* linux/drivers/cpufreq/cpufreq_userspace.c
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*
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* Copyright (C) 2001 Russell King
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* (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
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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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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/cpufreq.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
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static DEFINE_MUTEX(userspace_mutex);
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/**
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* cpufreq_set - set the CPU frequency
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* @policy: pointer to policy struct where freq is being set
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* @freq: target frequency in kHz
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*
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* Sets the CPU frequency to freq.
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*/
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static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
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{
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int ret = -EINVAL;
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pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
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mutex_lock(&userspace_mutex);
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if (!per_cpu(cpu_is_managed, policy->cpu))
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goto err;
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/*
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* We're safe from concurrent calls to ->target() here
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* as we hold the userspace_mutex lock. If we were calling
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* cpufreq_driver_target, a deadlock situation might occur:
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* A: cpufreq_set (lock userspace_mutex) ->
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* cpufreq_driver_target(lock policy->lock)
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* B: cpufreq_set_policy(lock policy->lock) ->
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* __cpufreq_governor ->
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* cpufreq_governor_userspace (lock userspace_mutex)
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*/
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ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
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err:
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mutex_unlock(&userspace_mutex);
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return ret;
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}
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static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
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{
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return sprintf(buf, "%u\n", policy->cur);
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}
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static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
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unsigned int event)
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{
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unsigned int cpu = policy->cpu;
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int rc = 0;
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switch (event) {
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case CPUFREQ_GOV_START:
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BUG_ON(!policy->cur);
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pr_debug("started managing cpu %u\n", cpu);
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mutex_lock(&userspace_mutex);
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per_cpu(cpu_is_managed, cpu) = 1;
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mutex_unlock(&userspace_mutex);
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break;
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case CPUFREQ_GOV_STOP:
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pr_debug("managing cpu %u stopped\n", cpu);
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mutex_lock(&userspace_mutex);
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per_cpu(cpu_is_managed, cpu) = 0;
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mutex_unlock(&userspace_mutex);
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break;
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case CPUFREQ_GOV_LIMITS:
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mutex_lock(&userspace_mutex);
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pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz\n",
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cpu, policy->min, policy->max,
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policy->cur);
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if (policy->max < policy->cur)
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__cpufreq_driver_target(policy, policy->max,
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CPUFREQ_RELATION_H);
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else if (policy->min > policy->cur)
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__cpufreq_driver_target(policy, policy->min,
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CPUFREQ_RELATION_L);
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mutex_unlock(&userspace_mutex);
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break;
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}
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return rc;
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}
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#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
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static
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#endif
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struct cpufreq_governor cpufreq_gov_userspace = {
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.name = "userspace",
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.governor = cpufreq_governor_userspace,
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.store_setspeed = cpufreq_set,
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.show_setspeed = show_speed,
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.owner = THIS_MODULE,
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};
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static int __init cpufreq_gov_userspace_init(void)
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{
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return cpufreq_register_governor(&cpufreq_gov_userspace);
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}
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static void __exit cpufreq_gov_userspace_exit(void)
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{
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cpufreq_unregister_governor(&cpufreq_gov_userspace);
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}
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MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
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"Russell King <rmk@arm.linux.org.uk>");
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MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
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MODULE_LICENSE("GPL");
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#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
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fs_initcall(cpufreq_gov_userspace_init);
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#else
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module_init(cpufreq_gov_userspace_init);
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#endif
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module_exit(cpufreq_gov_userspace_exit);
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