Root/drivers/devfreq/governor_simpleondemand.c

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    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;
30    unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
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) {
47        *freq = max;
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) {
60        *freq = max;
61        return 0;
62    }
63
64    /* Set MAX if we do not know the initial frequency */
65    if (stat.current_frequency == 0) {
66        *freq = max;
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
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
90    return 0;
91}
92
93static 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;
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
117    default:
118        break;
119    }
120
121    return 0;
122}
123
124static struct devfreq_governor devfreq_simple_ondemand = {
125    .name = "simple_ondemand",
126    .get_target_freq = devfreq_simple_ondemand_func,
127    .event_handler = devfreq_simple_ondemand_handler,
128};
129
130static int __init devfreq_simple_ondemand_init(void)
131{
132    return devfreq_add_governor(&devfreq_simple_ondemand);
133}
134subsys_initcall(devfreq_simple_ondemand_init);
135
136static 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}
146module_exit(devfreq_simple_ondemand_exit);
147MODULE_LICENSE("GPL");
148

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive