1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
/*
* linux/drivers/devfreq/governor_passive.c
*
* Copyright (C) 2016 Samsung Electronics
* Author: Chanwoo Choi <cw00.choi@samsung.com>
* Author: MyungJoo Ham <myungjoo.ham@samsung.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include "governor.h"
static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
unsigned long *freq)
{
struct devfreq_passive_data *p_data
= (struct devfreq_passive_data *)devfreq->data;
struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
unsigned long child_freq = ULONG_MAX;
struct dev_pm_opp *opp;
int i, count, ret = 0;
/*
* If the devfreq device with passive governor has the specific method
* to determine the next frequency, should use the get_target_freq()
* of struct devfreq_passive_data.
*/
if (p_data->get_target_freq) {
ret = p_data->get_target_freq(devfreq, freq);
goto out;
}
/*
* If the parent and passive devfreq device uses the OPP table,
* get the next frequency by using the OPP table.
*/
/*
* - parent devfreq device uses the governors except for passive.
* - passive devfreq device uses the passive governor.
*
* Each devfreq has the OPP table. After deciding the new frequency
* from the governor of parent devfreq device, the passive governor
* need to get the index of new frequency on OPP table of parent
* device. And then the index is used for getting the suitable
* new frequency for passive devfreq device.
*/
if (!devfreq->profile || !devfreq->profile->freq_table
|| devfreq->profile->max_state <= 0)
return -EINVAL;
/*
* The passive governor have to get the correct frequency from OPP
* list of parent device. Because in this case, *freq is temporary
* value which is decided by ondemand governor.
*/
rcu_read_lock();
opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
rcu_read_unlock();
if (IS_ERR(opp)) {
ret = PTR_ERR(opp);
goto out;
}
/*
* Get the OPP table's index of decided freqeuncy by governor
* of parent device.
*/
for (i = 0; i < parent_devfreq->profile->max_state; i++)
if (parent_devfreq->profile->freq_table[i] == *freq)
break;
if (i == parent_devfreq->profile->max_state) {
ret = -EINVAL;
goto out;
}
/* Get the suitable frequency by using index of parent device. */
if (i < devfreq->profile->max_state) {
child_freq = devfreq->profile->freq_table[i];
} else {
count = devfreq->profile->max_state;
child_freq = devfreq->profile->freq_table[count - 1];
}
/* Return the suitable frequency for passive device. */
*freq = child_freq;
out:
return ret;
}
static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
{
int ret;
if (!devfreq->governor)
return -EINVAL;
mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
ret = devfreq->governor->get_target_freq(devfreq, &freq);
if (ret < 0)
goto out;
ret = devfreq->profile->target(devfreq->dev.parent, &freq, 0);
if (ret < 0)
goto out;
devfreq->previous_freq = freq;
out:
mutex_unlock(&devfreq->lock);
return 0;
}
static int devfreq_passive_notifier_call(struct notifier_block *nb,
unsigned long event, void *ptr)
{
struct devfreq_passive_data *data
= container_of(nb, struct devfreq_passive_data, nb);
struct devfreq *devfreq = (struct devfreq *)data->this;
struct devfreq *parent = (struct devfreq *)data->parent;
struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
unsigned long freq = freqs->new;
switch (event) {
case DEVFREQ_PRECHANGE:
if (parent->previous_freq > freq)
update_devfreq_passive(devfreq, freq);
break;
case DEVFREQ_POSTCHANGE:
if (parent->previous_freq < freq)
update_devfreq_passive(devfreq, freq);
break;
}
return NOTIFY_DONE;
}
static int devfreq_passive_event_handler(struct devfreq *devfreq,
unsigned int event, void *data)
{
struct device *dev = devfreq->dev.parent;
struct devfreq_passive_data *p_data
= (struct devfreq_passive_data *)devfreq->data;
struct devfreq *parent = (struct devfreq *)p_data->parent;
struct notifier_block *nb = &p_data->nb;
int ret = 0;
if (!parent)
return -EPROBE_DEFER;
switch (event) {
case DEVFREQ_GOV_START:
if (!p_data->this)
p_data->this = devfreq;
nb->notifier_call = devfreq_passive_notifier_call;
ret = devm_devfreq_register_notifier(dev, parent, nb,
DEVFREQ_TRANSITION_NOTIFIER);
break;
case DEVFREQ_GOV_STOP:
devm_devfreq_unregister_notifier(dev, parent, nb,
DEVFREQ_TRANSITION_NOTIFIER);
break;
default:
break;
}
return ret;
}
static struct devfreq_governor devfreq_passive = {
.name = "passive",
.get_target_freq = devfreq_passive_get_target_freq,
.event_handler = devfreq_passive_event_handler,
};
static int __init devfreq_passive_init(void)
{
return devfreq_add_governor(&devfreq_passive);
}
subsys_initcall(devfreq_passive_init);
static void __exit devfreq_passive_exit(void)
{
int ret;
ret = devfreq_remove_governor(&devfreq_passive);
if (ret)
pr_err("%s: failed remove governor %d\n", __func__, ret);
return;
}
module_exit(devfreq_passive_exit);
MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_DESCRIPTION("DEVFREQ Passive governor");
MODULE_LICENSE("GPL v2");
|
