[linux-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;

	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 = DEVFREQ_MAX_FREQ;
		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 = DEVFREQ_MAX_FREQ;
		return 0;
	}

	/* Set MAX if we do not know the initial frequency */
	if (stat->current_frequency == 0) {
		*freq = DEVFREQ_MAX_FREQ;
		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;

	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 = DEVFREQ_GOV_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;
	30
08e75e75	31	err = devfreq_update_stats(df);
ce26c5bb MH	32	if (err)
	33	return err;
	34
08e75e75 JM	35	stat = &df->last_status;
08e75e75 JM	36
ce26c5bb MH	37	if (data) {
	38	if (data->upthreshold)
	39	dfso_upthreshold = data->upthreshold;
	40	if (data->downdifferential)
	41	dfso_downdifferential = data->downdifferential;
	42	}
	43	if (dfso_upthreshold > 100 \|\|
	44	dfso_upthreshold < dfso_downdifferential)
	45	return -EINVAL;
	46
	47	/* Assume MAX if it is going to be divided by zero */
08e75e75	48	if (stat->total_time == 0) {
6ff66e2a	49	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	50	return 0;
	51	}
	52
	53	/* Prevent overflow */
08e75e75 JM	54	if (stat->busy_time >= (1 << 24) \|\| stat->total_time >= (1 << 24)) {
	55	stat->busy_time >>= 7;
	56	stat->total_time >>= 7;
ce26c5bb MH	57	}
	58
	59	/* Set MAX if it's busy enough */
08e75e75 JM	60	if (stat->busy_time * 100 >
08e75e75 JM	61	stat->total_time * dfso_upthreshold) {
6ff66e2a	62	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	63	return 0;
	64	}
	65
	66	/* Set MAX if we do not know the initial frequency */
08e75e75	67	if (stat->current_frequency == 0) {
6ff66e2a	68	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	69	return 0;
	70	}
	71
	72	/* Keep the current frequency */
08e75e75 JM	73	if (stat->busy_time * 100 >
	74	stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
	75	*freq = stat->current_frequency;
ce26c5bb MH	76	return 0;
	77	}
	78
	79	/* Set the desired frequency based on the load */
08e75e75 JM	80	a = stat->busy_time;
	81	a *= stat->current_frequency;
	82	b = div_u64(a, stat->total_time);
ce26c5bb MH	83	b *= 100;
	84	b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
	85	*freq = (unsigned long) b;
	86
	87	return 0;
	88	}
	89
7e6fdd4b RV	90	static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
	91	unsigned int event, void *data)
	92	{
	93	switch (event) {
	94	case DEVFREQ_GOV_START:
	95	devfreq_monitor_start(devfreq);
	96	break;
	97
	98	case DEVFREQ_GOV_STOP:
	99	devfreq_monitor_stop(devfreq);
	100	break;
	101
	102	case DEVFREQ_GOV_INTERVAL:
	103	devfreq_interval_update(devfreq, (unsigned int *)data);
	104	break;
206c30cf RV	105
	106	case DEVFREQ_GOV_SUSPEND:
	107	devfreq_monitor_suspend(devfreq);
	108	break;
	109
	110	case DEVFREQ_GOV_RESUME:
	111	devfreq_monitor_resume(devfreq);
	112	break;
	113
7e6fdd4b RV	114	default:
	115	break;
	116	}
	117
	118	return 0;
	119	}
	120
1b5c1be2	121	static struct devfreq_governor devfreq_simple_ondemand = {
aa7c352f	122	.name = DEVFREQ_GOV_SIMPLE_ONDEMAND,
ce26c5bb	123	.get_target_freq = devfreq_simple_ondemand_func,
7e6fdd4b	124	.event_handler = devfreq_simple_ondemand_handler,
ce26c5bb	125	};
83116e66 NM	126
	127	static int __init devfreq_simple_ondemand_init(void)
	128	{
	129	return devfreq_add_governor(&devfreq_simple_ondemand);
	130	}
	131	subsys_initcall(devfreq_simple_ondemand_init);
	132
	133	static void __exit devfreq_simple_ondemand_exit(void)
	134	{
	135	int ret;
	136
	137	ret = devfreq_remove_governor(&devfreq_simple_ondemand);
	138	if (ret)
	139	pr_err("%s: failed remove governor %d\n", __func__, ret);
	140
	141	return;
	142	}
	143	module_exit(devfreq_simple_ondemand_exit);
eff607fd	144	MODULE_LICENSE("GPL");