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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> |
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 | { | |
24 | struct devfreq_dev_status stat; | |
25 | int err = df->profile->get_dev_status(df->dev.parent, &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; | |
6530b9de | 30 | unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX; |
ce26c5bb MH |
31 | |
32 | if (err) | |
33 | return err; | |
34 | ||
35 | if (data) { | |
36 | if (data->upthreshold) | |
37 | dfso_upthreshold = data->upthreshold; | |
38 | if (data->downdifferential) | |
39 | dfso_downdifferential = data->downdifferential; | |
40 | } | |
41 | if (dfso_upthreshold > 100 || | |
42 | dfso_upthreshold < dfso_downdifferential) | |
43 | return -EINVAL; | |
44 | ||
45 | /* Assume MAX if it is going to be divided by zero */ | |
46 | if (stat.total_time == 0) { | |
6530b9de | 47 | *freq = max; |
ce26c5bb MH |
48 | return 0; |
49 | } | |
50 | ||
51 | /* Prevent overflow */ | |
52 | if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) { | |
53 | stat.busy_time >>= 7; | |
54 | stat.total_time >>= 7; | |
55 | } | |
56 | ||
57 | /* Set MAX if it's busy enough */ | |
58 | if (stat.busy_time * 100 > | |
59 | stat.total_time * dfso_upthreshold) { | |
6530b9de | 60 | *freq = max; |
ce26c5bb MH |
61 | return 0; |
62 | } | |
63 | ||
64 | /* Set MAX if we do not know the initial frequency */ | |
65 | if (stat.current_frequency == 0) { | |
6530b9de | 66 | *freq = max; |
ce26c5bb MH |
67 | return 0; |
68 | } | |
69 | ||
70 | /* Keep the current frequency */ | |
71 | if (stat.busy_time * 100 > | |
72 | stat.total_time * (dfso_upthreshold - dfso_downdifferential)) { | |
73 | *freq = stat.current_frequency; | |
74 | return 0; | |
75 | } | |
76 | ||
77 | /* Set the desired frequency based on the load */ | |
78 | a = stat.busy_time; | |
79 | a *= stat.current_frequency; | |
80 | b = div_u64(a, stat.total_time); | |
81 | b *= 100; | |
82 | b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2)); | |
83 | *freq = (unsigned long) b; | |
84 | ||
6530b9de MH |
85 | if (df->min_freq && *freq < df->min_freq) |
86 | *freq = df->min_freq; | |
87 | if (df->max_freq && *freq > df->max_freq) | |
88 | *freq = df->max_freq; | |
89 | ||
ce26c5bb MH |
90 | return 0; |
91 | } | |
92 | ||
7e6fdd4b RV |
93 | static int devfreq_simple_ondemand_handler(struct devfreq *devfreq, |
94 | unsigned int event, void *data) | |
95 | { | |
96 | switch (event) { | |
97 | case DEVFREQ_GOV_START: | |
98 | devfreq_monitor_start(devfreq); | |
99 | break; | |
100 | ||
101 | case DEVFREQ_GOV_STOP: | |
102 | devfreq_monitor_stop(devfreq); | |
103 | break; | |
104 | ||
105 | case DEVFREQ_GOV_INTERVAL: | |
106 | devfreq_interval_update(devfreq, (unsigned int *)data); | |
107 | break; | |
206c30cf RV |
108 | |
109 | case DEVFREQ_GOV_SUSPEND: | |
110 | devfreq_monitor_suspend(devfreq); | |
111 | break; | |
112 | ||
113 | case DEVFREQ_GOV_RESUME: | |
114 | devfreq_monitor_resume(devfreq); | |
115 | break; | |
116 | ||
7e6fdd4b RV |
117 | default: |
118 | break; | |
119 | } | |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
1b5c1be2 | 124 | static struct devfreq_governor devfreq_simple_ondemand = { |
ce26c5bb MH |
125 | .name = "simple_ondemand", |
126 | .get_target_freq = devfreq_simple_ondemand_func, | |
7e6fdd4b | 127 | .event_handler = devfreq_simple_ondemand_handler, |
ce26c5bb | 128 | }; |
83116e66 NM |
129 | |
130 | static int __init devfreq_simple_ondemand_init(void) | |
131 | { | |
132 | return devfreq_add_governor(&devfreq_simple_ondemand); | |
133 | } | |
134 | subsys_initcall(devfreq_simple_ondemand_init); | |
135 | ||
136 | static void __exit devfreq_simple_ondemand_exit(void) | |
137 | { | |
138 | int ret; | |
139 | ||
140 | ret = devfreq_remove_governor(&devfreq_simple_ondemand); | |
141 | if (ret) | |
142 | pr_err("%s: failed remove governor %d\n", __func__, ret); | |
143 | ||
144 | return; | |
145 | } | |
146 | module_exit(devfreq_simple_ondemand_exit); | |
eff607fd | 147 | MODULE_LICENSE("GPL"); |