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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/module.h>
14#include <linux/devfreq.h>
15#include <linux/math64.h>
16#include "governor.h"
17
18/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
19#define DFSO_UPTHRESHOLD (90)
20#define DFSO_DOWNDIFFERENCTIAL (5)
21static int devfreq_simple_ondemand_func(struct devfreq *df,
22 unsigned long *freq)
23{
24 int err;
25 struct devfreq_dev_status *stat;
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 unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
31
32 err = devfreq_update_stats(df);
33 if (err)
34 return err;
35
36 stat = &df->last_status;
37
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 */
49 if (stat->total_time == 0) {
50 *freq = max;
51 return 0;
52 }
53
54 /* Prevent overflow */
55 if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) {
56 stat->busy_time >>= 7;
57 stat->total_time >>= 7;
58 }
59
60 /* Set MAX if it's busy enough */
61 if (stat->busy_time * 100 >
62 stat->total_time * dfso_upthreshold) {
63 *freq = max;
64 return 0;
65 }
66
67 /* Set MAX if we do not know the initial frequency */
68 if (stat->current_frequency == 0) {
69 *freq = max;
70 return 0;
71 }
72
73 /* Keep the current frequency */
74 if (stat->busy_time * 100 >
75 stat->total_time * (dfso_upthreshold - dfso_downdifferential)) {
76 *freq = stat->current_frequency;
77 return 0;
78 }
79
80 /* Set the desired frequency based on the load */
81 a = stat->busy_time;
82 a *= stat->current_frequency;
83 b = div_u64(a, stat->total_time);
84 b *= 100;
85 b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
86 *freq = (unsigned long) b;
87
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
93 return 0;
94}
95
96static 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;
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
120 default:
121 break;
122 }
123
124 return 0;
125}
126
127static struct devfreq_governor devfreq_simple_ondemand = {
128 .name = "simple_ondemand",
129 .get_target_freq = devfreq_simple_ondemand_func,
130 .event_handler = devfreq_simple_ondemand_handler,
131};
132
133static int __init devfreq_simple_ondemand_init(void)
134{
135 return devfreq_add_governor(&devfreq_simple_ondemand);
136}
137subsys_initcall(devfreq_simple_ondemand_init);
138
139static 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}
149module_exit(devfreq_simple_ondemand_exit);
150MODULE_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};