144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* linux/drivers/devfreq/governor_simpleondemand.c
|
|
*
|
|
* Copyright (C) 2011 Samsung Electronics
|
|
* MyungJoo Ham <myungjoo.ham@samsung.com>
|
|
*/
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/module.h>
|
|
#include <linux/devfreq.h>
|
|
#include <linux/math64.h>
|
|
#include "governor.h"
|
|
|
|
/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
|
|
#define DFSO_UPTHRESHOLD (90)
|
|
#define DFSO_DOWNDIFFERENCTIAL (5)
|
|
static int devfreq_simple_ondemand_func(struct devfreq *df,
|
|
unsigned long *freq)
|
|
{
|
|
int err;
|
|
struct devfreq_dev_status *stat;
|
|
unsigned long long a, b;
|
|
unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
|
|
unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
|
|
struct devfreq_simple_ondemand_data *data = df->data;
|
|
|
|
err = devfreq_update_stats(df);
|
|
if (err)
|
|
return err;
|
|
|
|
stat = &df->last_status;
|
|
|
|
if (data) {
|
|
if (data->upthreshold)
|
|
dfso_upthreshold = data->upthreshold;
|
|
if (data->downdifferential)
|
|
dfso_downdifferential = data->downdifferential;
|
|
}
|
|
if (dfso_upthreshold > 100 ||
|
|
dfso_upthreshold < dfso_downdifferential)
|
|
return -EINVAL;
|
|
|
|
/* Assume MAX if it is going to be divided by zero */
|
|
if (stat->total_time == 0) {
|
|
*freq = DEVFREQ_MAX_FREQ;
|
|
return 0;
|
|
}
|
|
|
|
/* Prevent overflow */
|
|
if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) {
|
|
stat->busy_time >>= 7;
|
|
stat->total_time >>= 7;
|
|
}
|
|
|
|
/* Set MAX if it's busy enough */
|
|
if (stat->busy_time * 100 >
|
|
stat->total_time * dfso_upthreshold) {
|
|
*freq = DEVFREQ_MAX_FREQ;
|
|
return 0;
|
|
}
|
|
|
|
/* Set MAX if we do not know the initial frequency */
|
|
if (stat->current_frequency == 0) {
|
|
*freq = DEVFREQ_MAX_FREQ;
|
|
return 0;
|
|
}
|
|
|
|
/* Keep the current frequency */
|
|
if (stat->busy_time * 100 >
|
|
stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
|
|
*freq = stat->current_frequency;
|
|
return 0;
|
|
}
|
|
|
|
/* Set the desired frequency based on the load */
|
|
a = stat->busy_time;
|
|
a *= stat->current_frequency;
|
|
b = div_u64(a, stat->total_time);
|
|
b *= 100;
|
|
b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
|
|
*freq = (unsigned long) b;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
|
|
unsigned int event, void *data)
|
|
{
|
|
switch (event) {
|
|
case DEVFREQ_GOV_START:
|
|
devfreq_monitor_start(devfreq);
|
|
break;
|
|
|
|
case DEVFREQ_GOV_STOP:
|
|
devfreq_monitor_stop(devfreq);
|
|
break;
|
|
|
|
case DEVFREQ_GOV_UPDATE_INTERVAL:
|
|
devfreq_update_interval(devfreq, (unsigned int *)data);
|
|
break;
|
|
|
|
case DEVFREQ_GOV_SUSPEND:
|
|
devfreq_monitor_suspend(devfreq);
|
|
break;
|
|
|
|
case DEVFREQ_GOV_RESUME:
|
|
devfreq_monitor_resume(devfreq);
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct devfreq_governor devfreq_simple_ondemand = {
|
|
.name = DEVFREQ_GOV_SIMPLE_ONDEMAND,
|
|
.attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL
|
|
| DEVFREQ_GOV_ATTR_TIMER,
|
|
.get_target_freq = devfreq_simple_ondemand_func,
|
|
.event_handler = devfreq_simple_ondemand_handler,
|
|
};
|
|
|
|
static int __init devfreq_simple_ondemand_init(void)
|
|
{
|
|
return devfreq_add_governor(&devfreq_simple_ondemand);
|
|
}
|
|
subsys_initcall(devfreq_simple_ondemand_init);
|
|
|
|
static void __exit devfreq_simple_ondemand_exit(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = devfreq_remove_governor(&devfreq_simple_ondemand);
|
|
if (ret)
|
|
pr_err("%s: failed remove governor %d\n", __func__, ret);
|
|
|
|
return;
|
|
}
|
|
module_exit(devfreq_simple_ondemand_exit);
|
|
MODULE_LICENSE("GPL");
|