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143 lines
3.3 KiB
143 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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 <[email protected]> |
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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_UPDATE_INTERVAL: |
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devfreq_update_interval(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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.attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL |
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| DEVFREQ_GOV_ATTR_TIMER, |
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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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