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/*
* linux/drivers/cpufreq/cpufreq_userspace.c
*
* Copyright (C) 2001 Russell King
* (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
/**
* A few values needed by the userspace governor
*/
static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
userspace */
static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
static DEFINE_MUTEX (userspace_mutex);
static int cpus_using_userspace_governor;
#define dprintk(msg...) \
cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
/* keep track of frequency transitions */
static int
userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
if (!per_cpu(cpu_is_managed, freq->cpu))
return 0;
dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
freq->cpu, freq->new);
per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
return 0;
}
static struct notifier_block userspace_cpufreq_notifier_block = {
.notifier_call = userspace_cpufreq_notifier
};
/**
* cpufreq_set - set the CPU frequency
* @policy: pointer to policy struct where freq is being set
* @freq: target frequency in kHz
*
* Sets the CPU frequency to freq.
*/
static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
{
int ret = -EINVAL;
dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
mutex_lock(&userspace_mutex);
if (!per_cpu(cpu_is_managed, policy->cpu))
goto err;
per_cpu(cpu_set_freq, policy->cpu) = freq;
if (freq < per_cpu(cpu_min_freq, policy->cpu))
freq = per_cpu(cpu_min_freq, policy->cpu);
if (freq > per_cpu(cpu_max_freq, policy->cpu))
freq = per_cpu(cpu_max_freq, policy->cpu);
/*
* We're safe from concurrent calls to ->target() here
* as we hold the userspace_mutex lock. If we were calling
* cpufreq_driver_target, a deadlock situation might occur:
* A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
* B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
*/
ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
err:
mutex_unlock(&userspace_mutex);
return ret;
}
static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
{
return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
}
static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
unsigned int event)
{
unsigned int cpu = policy->cpu;
int rc = 0;
switch (event) {
case CPUFREQ_GOV_START:
if (!cpu_online(cpu))
return -EINVAL;
BUG_ON(!policy->cur);
mutex_lock(&userspace_mutex);
if (cpus_using_userspace_governor == 0) {
cpufreq_register_notifier(
&userspace_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
}
cpus_using_userspace_governor++;
per_cpu(cpu_is_managed, cpu) = 1;
per_cpu(cpu_min_freq, cpu) = policy->min;
per_cpu(cpu_max_freq, cpu) = policy->max;
per_cpu(cpu_cur_freq, cpu) = policy->cur;
per_cpu(cpu_set_freq, cpu) = policy->cur;
dprintk("managing cpu %u started "
"(%u - %u kHz, currently %u kHz)\n",
cpu,
per_cpu(cpu_min_freq, cpu),
per_cpu(cpu_max_freq, cpu),
per_cpu(cpu_cur_freq, cpu));
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_STOP:
mutex_lock(&userspace_mutex);
cpus_using_userspace_governor--;
if (cpus_using_userspace_governor == 0) {
cpufreq_unregister_notifier(
&userspace_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
}
per_cpu(cpu_is_managed, cpu) = 0;
per_cpu(cpu_min_freq, cpu) = 0;
per_cpu(cpu_max_freq, cpu) = 0;
per_cpu(cpu_set_freq, cpu) = 0;
dprintk("managing cpu %u stopped\n", cpu);
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_LIMITS:
mutex_lock(&userspace_mutex);
dprintk("limit event for cpu %u: %u - %u kHz, "
"currently %u kHz, last set to %u kHz\n",
cpu, policy->min, policy->max,
per_cpu(cpu_cur_freq, cpu),
per_cpu(cpu_set_freq, cpu));
if (policy->max < per_cpu(cpu_set_freq, cpu)) {
__cpufreq_driver_target(policy, policy->max,
CPUFREQ_RELATION_H);
} else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
__cpufreq_driver_target(policy, policy->min,
CPUFREQ_RELATION_L);
} else {
__cpufreq_driver_target(policy,
per_cpu(cpu_set_freq, cpu),
CPUFREQ_RELATION_L);
}
per_cpu(cpu_min_freq, cpu) = policy->min;
per_cpu(cpu_max_freq, cpu) = policy->max;
per_cpu(cpu_cur_freq, cpu) = policy->cur;
mutex_unlock(&userspace_mutex);
break;
}
return rc;
}
struct cpufreq_governor cpufreq_gov_userspace = {
.name = "userspace",
.governor = cpufreq_governor_userspace,
.store_setspeed = cpufreq_set,
.show_setspeed = show_speed,
.owner = THIS_MODULE,
};
EXPORT_SYMBOL(cpufreq_gov_userspace);
static int __init cpufreq_gov_userspace_init(void)
{
return cpufreq_register_governor(&cpufreq_gov_userspace);
}
static void __exit cpufreq_gov_userspace_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_userspace);
}
MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
MODULE_LICENSE ("GPL");
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
fs_initcall(cpufreq_gov_userspace_init);
#else
module_init(cpufreq_gov_userspace_init);
#endif
module_exit(cpufreq_gov_userspace_exit);
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