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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/drivers/devfreq/governor_simpleondemand.c
4 *
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
7 */
8
9#include <linux/errno.h>
10#include <linux/module.h>
11#include <linux/devfreq.h>
12#include <linux/math64.h>
13#include "governor.h"
14
15/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
16#define DFSO_UPTHRESHOLD (90)
17#define DFSO_DOWNDIFFERENCTIAL (5)
18static int devfreq_simple_ondemand_func(struct devfreq *df,
19 unsigned long *freq)
20{
21 int err;
22 struct devfreq_dev_status *stat;
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
28 err = devfreq_update_stats(df);
29 if (err)
30 return err;
31
32 stat = &df->last_status;
33
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 */
45 if (stat->total_time == 0) {
46 *freq = DEVFREQ_MAX_FREQ;
47 return 0;
48 }
49
50 /* Prevent overflow */
51 if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) {
52 stat->busy_time >>= 7;
53 stat->total_time >>= 7;
54 }
55
56 /* Set MAX if it's busy enough */
57 if (stat->busy_time * 100 >
58 stat->total_time * dfso_upthreshold) {
59 *freq = DEVFREQ_MAX_FREQ;
60 return 0;
61 }
62
63 /* Set MAX if we do not know the initial frequency */
64 if (stat->current_frequency == 0) {
65 *freq = DEVFREQ_MAX_FREQ;
66 return 0;
67 }
68
69 /* Keep the current frequency */
70 if (stat->busy_time * 100 >
71 stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
72 *freq = stat->current_frequency;
73 return 0;
74 }
75
76 /* Set the desired frequency based on the load */
77 a = stat->busy_time;
78 a *= stat->current_frequency;
79 b = div_u64(a, stat->total_time);
80 b *= 100;
81 b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
82 *freq = (unsigned long) b;
83
84 return 0;
85}
86
87static 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
99 case DEVFREQ_GOV_UPDATE_INTERVAL:
100 devfreq_update_interval(devfreq, (unsigned int *)data);
101 break;
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
111 default:
112 break;
113 }
114
115 return 0;
116}
117
118static struct devfreq_governor devfreq_simple_ondemand = {
119 .name = DEVFREQ_GOV_SIMPLE_ONDEMAND,
120 .attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL
121 | DEVFREQ_GOV_ATTR_TIMER,
122 .get_target_freq = devfreq_simple_ondemand_func,
123 .event_handler = devfreq_simple_ondemand_handler,
124};
125
126static int __init devfreq_simple_ondemand_init(void)
127{
128 return devfreq_add_governor(&devfreq_simple_ondemand);
129}
130subsys_initcall(devfreq_simple_ondemand_init);
131
132static 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}
142module_exit(devfreq_simple_ondemand_exit);
143MODULE_LICENSE("GPL");
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>
13#include <linux/devfreq.h>
14#include <linux/math64.h>
15
16/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
17#define DFSO_UPTHRESHOLD (90)
18#define DFSO_DOWNDIFFERENCTIAL (5)
19static int devfreq_simple_ondemand_func(struct devfreq *df,
20 unsigned long *freq)
21{
22 struct devfreq_dev_status stat;
23 int err = df->profile->get_dev_status(df->dev.parent, &stat);
24 unsigned long long a, b;
25 unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
26 unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
27 struct devfreq_simple_ondemand_data *data = df->data;
28 unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
29
30 if (err)
31 return err;
32
33 if (data) {
34 if (data->upthreshold)
35 dfso_upthreshold = data->upthreshold;
36 if (data->downdifferential)
37 dfso_downdifferential = data->downdifferential;
38 }
39 if (dfso_upthreshold > 100 ||
40 dfso_upthreshold < dfso_downdifferential)
41 return -EINVAL;
42
43 /* Assume MAX if it is going to be divided by zero */
44 if (stat.total_time == 0) {
45 *freq = max;
46 return 0;
47 }
48
49 /* Prevent overflow */
50 if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
51 stat.busy_time >>= 7;
52 stat.total_time >>= 7;
53 }
54
55 /* Set MAX if it's busy enough */
56 if (stat.busy_time * 100 >
57 stat.total_time * dfso_upthreshold) {
58 *freq = max;
59 return 0;
60 }
61
62 /* Set MAX if we do not know the initial frequency */
63 if (stat.current_frequency == 0) {
64 *freq = max;
65 return 0;
66 }
67
68 /* Keep the current frequency */
69 if (stat.busy_time * 100 >
70 stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
71 *freq = stat.current_frequency;
72 return 0;
73 }
74
75 /* Set the desired frequency based on the load */
76 a = stat.busy_time;
77 a *= stat.current_frequency;
78 b = div_u64(a, stat.total_time);
79 b *= 100;
80 b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
81 *freq = (unsigned long) b;
82
83 if (df->min_freq && *freq < df->min_freq)
84 *freq = df->min_freq;
85 if (df->max_freq && *freq > df->max_freq)
86 *freq = df->max_freq;
87
88 return 0;
89}
90
91const struct devfreq_governor devfreq_simple_ondemand = {
92 .name = "simple_ondemand",
93 .get_target_freq = devfreq_simple_ondemand_func,
94};