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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 unsigned int cpu_max_freq[NR_CPUS];
static unsigned int cpu_min_freq[NR_CPUS];
static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
static unsigned int cpu_is_managed[NR_CPUS];
static DEFINE_MUTEX (userspace_mutex);
#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;
dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
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
* @freq: target frequency in kHz
* @cpu: CPU for which the frequency is to be set
*
* Sets the CPU frequency to freq.
*/
static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
{
int ret = -EINVAL;
dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
lock_cpu_hotplug();
mutex_lock(&userspace_mutex);
if (!cpu_is_managed[policy->cpu])
goto err;
cpu_set_freq[policy->cpu] = freq;
if (freq < cpu_min_freq[policy->cpu])
freq = cpu_min_freq[policy->cpu];
if (freq > cpu_max_freq[policy->cpu])
freq = 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);
unlock_cpu_hotplug();
return ret;
}
/************************** sysfs interface ************************/
static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
{
return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
}
static ssize_t
store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
{
unsigned int freq = 0;
unsigned int ret;
ret = sscanf (buf, "%u", &freq);
if (ret != 1)
return -EINVAL;
cpufreq_set(freq, policy);
return count;
}
static struct freq_attr freq_attr_scaling_setspeed =
{
.attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
.show = show_speed,
.store = store_speed,
};
static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
unsigned int event)
{
unsigned int cpu = policy->cpu;
switch (event) {
case CPUFREQ_GOV_START:
if (!cpu_online(cpu))
return -EINVAL;
BUG_ON(!policy->cur);
mutex_lock(&userspace_mutex);
cpu_is_managed[cpu] = 1;
cpu_min_freq[cpu] = policy->min;
cpu_max_freq[cpu] = policy->max;
cpu_cur_freq[cpu] = policy->cur;
cpu_set_freq[cpu] = policy->cur;
sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_STOP:
mutex_lock(&userspace_mutex);
cpu_is_managed[cpu] = 0;
cpu_min_freq[cpu] = 0;
cpu_max_freq[cpu] = 0;
cpu_set_freq[cpu] = 0;
sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
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,
cpu_cur_freq[cpu], cpu_set_freq[cpu]);
if (policy->max < cpu_set_freq[cpu]) {
__cpufreq_driver_target(policy, policy->max,
CPUFREQ_RELATION_H);
}
else if (policy->min > cpu_set_freq[cpu]) {
__cpufreq_driver_target(policy, policy->min,
CPUFREQ_RELATION_L);
}
else {
__cpufreq_driver_target(policy, cpu_set_freq[cpu],
CPUFREQ_RELATION_L);
}
cpu_min_freq[cpu] = policy->min;
cpu_max_freq[cpu] = policy->max;
cpu_cur_freq[cpu] = policy->cur;
mutex_unlock(&userspace_mutex);
break;
}
return 0;
}
struct cpufreq_governor cpufreq_gov_userspace = {
.name = "userspace",
.governor = cpufreq_governor_userspace,
.owner = THIS_MODULE,
};
EXPORT_SYMBOL(cpufreq_gov_userspace);
static int __init cpufreq_gov_userspace_init(void)
{
cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
return cpufreq_register_governor(&cpufreq_gov_userspace);
}
static void __exit cpufreq_gov_userspace_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_userspace);
cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
}
MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
MODULE_LICENSE ("GPL");
fs_initcall(cpufreq_gov_userspace_init);
module_exit(cpufreq_gov_userspace_exit);
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