Commit | Line | Data |
---|---|---|
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 | { | |
08e75e75 JM |
24 | int err; |
25 | struct devfreq_dev_status *stat; | |
ce26c5bb MH |
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 | 31 | |
08e75e75 | 32 | err = devfreq_update_stats(df); |
ce26c5bb MH |
33 | if (err) |
34 | return err; | |
35 | ||
08e75e75 JM |
36 | stat = &df->last_status; |
37 | ||
ce26c5bb MH |
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 */ | |
08e75e75 | 49 | if (stat->total_time == 0) { |
6530b9de | 50 | *freq = max; |
ce26c5bb MH |
51 | return 0; |
52 | } | |
53 | ||
54 | /* Prevent overflow */ | |
08e75e75 JM |
55 | if (stat->busy_time >= (1 << 24) || stat->total_time >= (1 << 24)) { |
56 | stat->busy_time >>= 7; | |
57 | stat->total_time >>= 7; | |
ce26c5bb MH |
58 | } |
59 | ||
60 | /* Set MAX if it's busy enough */ | |
08e75e75 JM |
61 | if (stat->busy_time * 100 > |
62 | stat->total_time * dfso_upthreshold) { | |
6530b9de | 63 | *freq = max; |
ce26c5bb MH |
64 | return 0; |
65 | } | |
66 | ||
67 | /* Set MAX if we do not know the initial frequency */ | |
08e75e75 | 68 | if (stat->current_frequency == 0) { |
6530b9de | 69 | *freq = max; |
ce26c5bb MH |
70 | return 0; |
71 | } | |
72 | ||
73 | /* Keep the current frequency */ | |
08e75e75 JM |
74 | if (stat->busy_time * 100 > |
75 | stat->total_time * (dfso_upthreshold - dfso_downdifferential)) { | |
76 | *freq = stat->current_frequency; | |
ce26c5bb MH |
77 | return 0; |
78 | } | |
79 | ||
80 | /* Set the desired frequency based on the load */ | |
08e75e75 JM |
81 | a = stat->busy_time; |
82 | a *= stat->current_frequency; | |
83 | b = div_u64(a, stat->total_time); | |
ce26c5bb MH |
84 | b *= 100; |
85 | b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2)); | |
86 | *freq = (unsigned long) b; | |
87 | ||
6530b9de MH |
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 | ||
ce26c5bb MH |
93 | return 0; |
94 | } | |
95 | ||
7e6fdd4b RV |
96 | static 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; | |
206c30cf RV |
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 | ||
7e6fdd4b RV |
120 | default: |
121 | break; | |
122 | } | |
123 | ||
124 | return 0; | |
125 | } | |
126 | ||
1b5c1be2 | 127 | static struct devfreq_governor devfreq_simple_ondemand = { |
ce26c5bb MH |
128 | .name = "simple_ondemand", |
129 | .get_target_freq = devfreq_simple_ondemand_func, | |
7e6fdd4b | 130 | .event_handler = devfreq_simple_ondemand_handler, |
ce26c5bb | 131 | }; |
83116e66 NM |
132 | |
133 | static int __init devfreq_simple_ondemand_init(void) | |
134 | { | |
135 | return devfreq_add_governor(&devfreq_simple_ondemand); | |
136 | } | |
137 | subsys_initcall(devfreq_simple_ondemand_init); | |
138 | ||
139 | static 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 | } | |
149 | module_exit(devfreq_simple_ondemand_exit); | |
eff607fd | 150 | MODULE_LICENSE("GPL"); |