| /* |
| * linux/drivers/devfreq/governor_simpleondemand.c |
| * |
| * Copyright (C) 2011 Samsung Electronics |
| * MyungJoo Ham <myungjoo.ham@samsung.com> |
| * |
| * 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/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, |
| u32 *flag) |
| { |
| struct devfreq_dev_status stat; |
| int err = df->profile->get_dev_status(df->dev.parent, &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; |
| unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX; |
| unsigned long min = (df->min_freq) ? df->min_freq : 0; |
| |
| if (err) |
| return err; |
| |
| 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; |
| |
| /* Prevent overflow */ |
| if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) { |
| stat.busy_time >>= 7; |
| stat.total_time >>= 7; |
| } |
| |
| if (data && data->simple_scaling) { |
| if (stat.busy_time * 100 > |
| stat.total_time * dfso_upthreshold) |
| *freq = max; |
| else if (stat.busy_time * 100 < |
| stat.total_time * |
| (dfso_upthreshold - dfso_downdifferential)) |
| *freq = min; |
| else |
| *freq = df->previous_freq; |
| return 0; |
| } |
| |
| /* Assume MAX if it is going to be divided by zero */ |
| if (stat.total_time == 0) { |
| *freq = max; |
| return 0; |
| } |
| |
| /* Set MAX if it's busy enough */ |
| if (stat.busy_time * 100 > |
| stat.total_time * dfso_upthreshold) { |
| *freq = max; |
| return 0; |
| } |
| |
| /* Set MAX if we do not know the initial frequency */ |
| if (stat.current_frequency == 0) { |
| *freq = max; |
| 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; |
| |
| if (df->min_freq && *freq < df->min_freq) |
| *freq = df->min_freq; |
| if (df->max_freq && *freq > df->max_freq) |
| *freq = df->max_freq; |
| |
| 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_INTERVAL: |
| devfreq_interval_update(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 = "simple_ondemand", |
| .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"); |