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Several governors use the user space limits df->min/max_freq to adjust the target frequency. This is not necessary, since update_devfreq() already takes care of this. Instead the governor can request the available min/max frequency by setting the target frequency to DEVFREQ_MIN/MAX_FREQ and let update_devfreq() take care of any adjustments. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Brian Norris <briannorris@chromium.org> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
144 lines
3.4 KiB
C
144 lines
3.4 KiB
C
/*
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* linux/drivers/devfreq/governor_simpleondemand.c
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*
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* Copyright (C) 2011 Samsung Electronics
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* MyungJoo Ham <myungjoo.ham@samsung.com>
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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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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/devfreq.h>
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#include <linux/math64.h>
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#include "governor.h"
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/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
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#define DFSO_UPTHRESHOLD (90)
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#define DFSO_DOWNDIFFERENCTIAL (5)
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static int devfreq_simple_ondemand_func(struct devfreq *df,
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unsigned long *freq)
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{
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int err;
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struct devfreq_dev_status *stat;
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unsigned long long a, b;
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unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
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unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
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struct devfreq_simple_ondemand_data *data = df->data;
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err = devfreq_update_stats(df);
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if (err)
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return err;
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stat = &df->last_status;
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if (data) {
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if (data->upthreshold)
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dfso_upthreshold = data->upthreshold;
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if (data->downdifferential)
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dfso_downdifferential = data->downdifferential;
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}
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if (dfso_upthreshold > 100 ||
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dfso_upthreshold < dfso_downdifferential)
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return -EINVAL;
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/* Assume MAX if it is going to be divided by zero */
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if (stat->total_time == 0) {
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*freq = DEVFREQ_MAX_FREQ;
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return 0;
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}
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/* Prevent overflow */
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if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) {
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stat->busy_time >>= 7;
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stat->total_time >>= 7;
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}
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/* Set MAX if it's busy enough */
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if (stat->busy_time * 100 >
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stat->total_time * dfso_upthreshold) {
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*freq = DEVFREQ_MAX_FREQ;
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return 0;
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}
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/* Set MAX if we do not know the initial frequency */
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if (stat->current_frequency == 0) {
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*freq = DEVFREQ_MAX_FREQ;
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return 0;
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}
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/* Keep the current frequency */
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if (stat->busy_time * 100 >
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stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
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*freq = stat->current_frequency;
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return 0;
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}
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/* Set the desired frequency based on the load */
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a = stat->busy_time;
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a *= stat->current_frequency;
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b = div_u64(a, stat->total_time);
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b *= 100;
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b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
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*freq = (unsigned long) b;
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return 0;
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}
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static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
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unsigned int event, void *data)
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{
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switch (event) {
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case DEVFREQ_GOV_START:
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devfreq_monitor_start(devfreq);
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break;
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case DEVFREQ_GOV_STOP:
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devfreq_monitor_stop(devfreq);
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break;
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case DEVFREQ_GOV_INTERVAL:
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devfreq_interval_update(devfreq, (unsigned int *)data);
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break;
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case DEVFREQ_GOV_SUSPEND:
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devfreq_monitor_suspend(devfreq);
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break;
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case DEVFREQ_GOV_RESUME:
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devfreq_monitor_resume(devfreq);
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break;
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default:
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break;
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}
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return 0;
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}
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static struct devfreq_governor devfreq_simple_ondemand = {
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.name = DEVFREQ_GOV_SIMPLE_ONDEMAND,
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.get_target_freq = devfreq_simple_ondemand_func,
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.event_handler = devfreq_simple_ondemand_handler,
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};
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static int __init devfreq_simple_ondemand_init(void)
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{
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return devfreq_add_governor(&devfreq_simple_ondemand);
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}
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subsys_initcall(devfreq_simple_ondemand_init);
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static void __exit devfreq_simple_ondemand_exit(void)
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{
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int ret;
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ret = devfreq_remove_governor(&devfreq_simple_ondemand);
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if (ret)
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pr_err("%s: failed remove governor %d\n", __func__, ret);
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return;
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}
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module_exit(devfreq_simple_ondemand_exit);
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MODULE_LICENSE("GPL");
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