governor_simpleondemand.rar_simple_ondemand

/* * linux/drivers/devfreq/governor_simpleondemand.c * * Copyright (C) 2011 Samsung Electronics * MyungJoo Ham <[email protected]> * * 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) { 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; 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; /* Assume MAX if it is going to be divided by zero */ if (stat.total_time == 0) { *freq = max; 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 = 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");