[linux-2.6-block.git] / drivers / devfreq / governor_simpleondemand.c

/*
 *  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)
{
	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;
	unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;

	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 = 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");
Commit	Line	Data
ce26c5bb MH	1	/*
	2	* linux/drivers/devfreq/governor_simpleondemand.c
	3	*
	4	* Copyright (C) 2011 Samsung Electronics
	5	* MyungJoo Ham <myungjoo.ham@samsung.com>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/errno.h>
eff607fd	13	#include <linux/module.h>
ce26c5bb MH	14	#include <linux/devfreq.h>
ce26c5bb MH	15	#include <linux/math64.h>
7e6fdd4b	16	#include "governor.h"
ce26c5bb MH	17
	18	/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
	19	#define DFSO_UPTHRESHOLD (90)
	20	#define DFSO_DOWNDIFFERENCTIAL (5)
	21	static int devfreq_simple_ondemand_func(struct devfreq *df,
	22	unsigned long *freq)
	23	{
08e75e75 JM	24	int err;
08e75e75 JM	25	struct devfreq_dev_status *stat;
ce26c5bb MH	26	unsigned long long a, b;
	27	unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
	28	unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
	29	struct devfreq_simple_ondemand_data *data = df->data;
6530b9de	30	unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
ce26c5bb	31
08e75e75	32	err = devfreq_update_stats(df);
ce26c5bb MH	33	if (err)
	34	return err;
	35
08e75e75 JM	36	stat = &df->last_status;
08e75e75 JM	37
ce26c5bb MH	38	if (data) {
	39	if (data->upthreshold)
	40	dfso_upthreshold = data->upthreshold;
	41	if (data->downdifferential)
	42	dfso_downdifferential = data->downdifferential;
	43	}
	44	if (dfso_upthreshold > 100 \|\|
	45	dfso_upthreshold < dfso_downdifferential)
	46	return -EINVAL;
	47
	48	/* Assume MAX if it is going to be divided by zero */
08e75e75	49	if (stat->total_time == 0) {
6530b9de	50	*freq = max;
ce26c5bb MH	51	return 0;
	52	}
	53
	54	/* Prevent overflow */
08e75e75 JM	55	if (stat->busy_time >= (1 << 24) \|\| stat->total_time >= (1 << 24)) {
	56	stat->busy_time >>= 7;
	57	stat->total_time >>= 7;
ce26c5bb MH	58	}
	59
	60	/* Set MAX if it's busy enough */
08e75e75 JM	61	if (stat->busy_time * 100 >
08e75e75 JM	62	stat->total_time * dfso_upthreshold) {
6530b9de	63	*freq = max;
ce26c5bb MH	64	return 0;
	65	}
	66
	67	/* Set MAX if we do not know the initial frequency */
08e75e75	68	if (stat->current_frequency == 0) {
6530b9de	69	*freq = max;
ce26c5bb MH	70	return 0;
	71	}
	72
	73	/* Keep the current frequency */
08e75e75 JM	74	if (stat->busy_time * 100 >
	75	stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
	76	*freq = stat->current_frequency;
ce26c5bb MH	77	return 0;
	78	}
	79
	80	/* Set the desired frequency based on the load */
08e75e75 JM	81	a = stat->busy_time;
	82	a *= stat->current_frequency;
	83	b = div_u64(a, stat->total_time);
ce26c5bb MH	84	b *= 100;
	85	b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
	86	*freq = (unsigned long) b;
	87
6530b9de MH	88	if (df->min_freq && *freq < df->min_freq)
	89	*freq = df->min_freq;
	90	if (df->max_freq && *freq > df->max_freq)
	91	*freq = df->max_freq;
	92
ce26c5bb MH	93	return 0;
	94	}
	95
7e6fdd4b RV	96	static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
	97	unsigned int event, void *data)
	98	{
	99	switch (event) {
	100	case DEVFREQ_GOV_START:
	101	devfreq_monitor_start(devfreq);
	102	break;
	103
	104	case DEVFREQ_GOV_STOP:
	105	devfreq_monitor_stop(devfreq);
	106	break;
	107
	108	case DEVFREQ_GOV_INTERVAL:
	109	devfreq_interval_update(devfreq, (unsigned int *)data);
	110	break;
206c30cf RV	111
	112	case DEVFREQ_GOV_SUSPEND:
	113	devfreq_monitor_suspend(devfreq);
	114	break;
	115
	116	case DEVFREQ_GOV_RESUME:
	117	devfreq_monitor_resume(devfreq);
	118	break;
	119
7e6fdd4b RV	120	default:
	121	break;
	122	}
	123
	124	return 0;
	125	}
	126
1b5c1be2	127	static struct devfreq_governor devfreq_simple_ondemand = {
ce26c5bb MH	128	.name = "simple_ondemand",
ce26c5bb MH	129	.get_target_freq = devfreq_simple_ondemand_func,
7e6fdd4b	130	.event_handler = devfreq_simple_ondemand_handler,
ce26c5bb	131	};
83116e66 NM	132
	133	static int __init devfreq_simple_ondemand_init(void)
	134	{
	135	return devfreq_add_governor(&devfreq_simple_ondemand);
	136	}
	137	subsys_initcall(devfreq_simple_ondemand_init);
	138
	139	static void __exit devfreq_simple_ondemand_exit(void)
	140	{
	141	int ret;
	142
	143	ret = devfreq_remove_governor(&devfreq_simple_ondemand);
	144	if (ret)
	145	pr_err("%s: failed remove governor %d\n", __func__, ret);
	146
	147	return;
	148	}
	149	module_exit(devfreq_simple_ondemand_exit);
eff607fd	150	MODULE_LICENSE("GPL");