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PM / devfreq: map devfreq drivers to governor using name
[mirror_ubuntu-jammy-kernel.git] / drivers / devfreq / governor_simpleondemand.c
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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/devfreq.h>
14#include <linux/math64.h>
7e6fdd4b 15#include "governor.h"
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16
17/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
18#define DFSO_UPTHRESHOLD (90)
19#define DFSO_DOWNDIFFERENCTIAL (5)
20static int devfreq_simple_ondemand_func(struct devfreq *df,
21 unsigned long *freq)
22{
23 struct devfreq_dev_status stat;
24 int err = df->profile->get_dev_status(df->dev.parent, &stat);
25 unsigned long long a, b;
26 unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
27 unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
28 struct devfreq_simple_ondemand_data *data = df->data;
6530b9de 29 unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
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30
31 if (err)
32 return err;
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) {
6530b9de 46 *freq = max;
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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) {
6530b9de 59 *freq = max;
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60 return 0;
61 }
62
63 /* Set MAX if we do not know the initial frequency */
64 if (stat.current_frequency == 0) {
6530b9de 65 *freq = max;
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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
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84 if (df->min_freq && *freq < df->min_freq)
85 *freq = df->min_freq;
86 if (df->max_freq && *freq > df->max_freq)
87 *freq = df->max_freq;
88
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89 return 0;
90}
91
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92static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
93 unsigned int event, void *data)
94{
95 switch (event) {
96 case DEVFREQ_GOV_START:
97 devfreq_monitor_start(devfreq);
98 break;
99
100 case DEVFREQ_GOV_STOP:
101 devfreq_monitor_stop(devfreq);
102 break;
103
104 case DEVFREQ_GOV_INTERVAL:
105 devfreq_interval_update(devfreq, (unsigned int *)data);
106 break;
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107
108 case DEVFREQ_GOV_SUSPEND:
109 devfreq_monitor_suspend(devfreq);
110 break;
111
112 case DEVFREQ_GOV_RESUME:
113 devfreq_monitor_resume(devfreq);
114 break;
115
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116 default:
117 break;
118 }
119
120 return 0;
121}
122
1b5c1be2 123static struct devfreq_governor devfreq_simple_ondemand = {
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124 .name = "simple_ondemand",
125 .get_target_freq = devfreq_simple_ondemand_func,
7e6fdd4b 126 .event_handler = devfreq_simple_ondemand_handler,
ce26c5bb 127};
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128
129static int __init devfreq_simple_ondemand_init(void)
130{
131 return devfreq_add_governor(&devfreq_simple_ondemand);
132}
133subsys_initcall(devfreq_simple_ondemand_init);
134
135static void __exit devfreq_simple_ondemand_exit(void)
136{
137 int ret;
138
139 ret = devfreq_remove_governor(&devfreq_simple_ondemand);
140 if (ret)
141 pr_err("%s: failed remove governor %d\n", __func__, ret);
142
143 return;
144}
145module_exit(devfreq_simple_ondemand_exit);