Make vfio MSI interrupt be non-threaded.
[kvmfornfv.git] / kernel / 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)
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;
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
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;
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
124 static 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
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);
147 MODULE_LICENSE("GPL");