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

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/drivers/devfreq/governor_simpleondemand.c
 *
 *  Copyright (C) 2011 Samsung Electronics
 *	MyungJoo Ham <myungjoo.ham@samsung.com>
 */

#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_UPDATE_INTERVAL:
		devfreq_update_interval(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,
	.attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL
		| DEVFREQ_GOV_ATTR_TIMER,
	.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
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
ce26c5bb MH	2	/*
	3	* linux/drivers/devfreq/governor_simpleondemand.c
	4	*
	5	* Copyright (C) 2011 Samsung Electronics
	6	* MyungJoo Ham <myungjoo.ham@samsung.com>
ce26c5bb MH	7	*/
	8
	9	#include <linux/errno.h>
eff607fd	10	#include <linux/module.h>
ce26c5bb MH	11	#include <linux/devfreq.h>
ce26c5bb MH	12	#include <linux/math64.h>
7e6fdd4b	13	#include "governor.h"
ce26c5bb MH	14
	15	/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
	16	#define DFSO_UPTHRESHOLD (90)
	17	#define DFSO_DOWNDIFFERENCTIAL (5)
	18	static int devfreq_simple_ondemand_func(struct devfreq *df,
	19	unsigned long *freq)
	20	{
08e75e75 JM	21	int err;
08e75e75 JM	22	struct devfreq_dev_status *stat;
ce26c5bb MH	23	unsigned long long a, b;
	24	unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
	25	unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
	26	struct devfreq_simple_ondemand_data *data = df->data;
	27
08e75e75	28	err = devfreq_update_stats(df);
ce26c5bb MH	29	if (err)
	30	return err;
	31
08e75e75 JM	32	stat = &df->last_status;
08e75e75 JM	33
ce26c5bb MH	34	if (data) {
	35	if (data->upthreshold)
	36	dfso_upthreshold = data->upthreshold;
	37	if (data->downdifferential)
	38	dfso_downdifferential = data->downdifferential;
	39	}
	40	if (dfso_upthreshold > 100 \|\|
	41	dfso_upthreshold < dfso_downdifferential)
	42	return -EINVAL;
	43
	44	/* Assume MAX if it is going to be divided by zero */
08e75e75	45	if (stat->total_time == 0) {
6ff66e2a	46	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	47	return 0;
	48	}
	49
	50	/* Prevent overflow */
08e75e75 JM	51	if (stat->busy_time >= (1 << 24) \|\| stat->total_time >= (1 << 24)) {
	52	stat->busy_time >>= 7;
	53	stat->total_time >>= 7;
ce26c5bb MH	54	}
	55
	56	/* Set MAX if it's busy enough */
08e75e75 JM	57	if (stat->busy_time * 100 >
08e75e75 JM	58	stat->total_time * dfso_upthreshold) {
6ff66e2a	59	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	60	return 0;
	61	}
	62
	63	/* Set MAX if we do not know the initial frequency */
08e75e75	64	if (stat->current_frequency == 0) {
6ff66e2a	65	*freq = DEVFREQ_MAX_FREQ;
ce26c5bb MH	66	return 0;
	67	}
	68
	69	/* Keep the current frequency */
08e75e75 JM	70	if (stat->busy_time * 100 >
	71	stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
	72	*freq = stat->current_frequency;
ce26c5bb MH	73	return 0;
	74	}
	75
	76	/* Set the desired frequency based on the load */
08e75e75 JM	77	a = stat->busy_time;
	78	a *= stat->current_frequency;
	79	b = div_u64(a, stat->total_time);
ce26c5bb MH	80	b *= 100;
	81	b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
	82	*freq = (unsigned long) b;
	83
	84	return 0;
	85	}
	86
7e6fdd4b RV	87	static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
	88	unsigned int event, void *data)
	89	{
	90	switch (event) {
	91	case DEVFREQ_GOV_START:
	92	devfreq_monitor_start(devfreq);
	93	break;
	94
	95	case DEVFREQ_GOV_STOP:
	96	devfreq_monitor_stop(devfreq);
	97	break;
	98
3a1ec2e8 CC	99	case DEVFREQ_GOV_UPDATE_INTERVAL:
3a1ec2e8 CC	100	devfreq_update_interval(devfreq, (unsigned int *)data);
7e6fdd4b	101	break;
206c30cf RV	102
	103	case DEVFREQ_GOV_SUSPEND:
	104	devfreq_monitor_suspend(devfreq);
	105	break;
	106
	107	case DEVFREQ_GOV_RESUME:
	108	devfreq_monitor_resume(devfreq);
	109	break;
	110
7e6fdd4b RV	111	default:
	112	break;
	113	}
	114
	115	return 0;
	116	}
	117
1b5c1be2	118	static struct devfreq_governor devfreq_simple_ondemand = {
aa7c352f	119	.name = DEVFREQ_GOV_SIMPLE_ONDEMAND,
5f1a9066 CC	120	.attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL
5f1a9066 CC	121	\| DEVFREQ_GOV_ATTR_TIMER,
ce26c5bb	122	.get_target_freq = devfreq_simple_ondemand_func,
7e6fdd4b	123	.event_handler = devfreq_simple_ondemand_handler,
ce26c5bb	124	};
83116e66 NM	125
	126	static int __init devfreq_simple_ondemand_init(void)
	127	{
	128	return devfreq_add_governor(&devfreq_simple_ondemand);
	129	}
	130	subsys_initcall(devfreq_simple_ondemand_init);
	131
	132	static void __exit devfreq_simple_ondemand_exit(void)
	133	{
	134	int ret;
	135
	136	ret = devfreq_remove_governor(&devfreq_simple_ondemand);
	137	if (ret)
	138	pr_err("%s: failed remove governor %d\n", __func__, ret);
	139
	140	return;
	141	}
	142	module_exit(devfreq_simple_ondemand_exit);
eff607fd	143	MODULE_LICENSE("GPL");