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1/*
2 * linux/drivers/devfreq/governor_passive.c
3 *
4 * Copyright (C) 2016 Samsung Electronics
5 * Author: Chanwoo Choi <cw00.choi@samsung.com>
6 * Author: MyungJoo Ham <myungjoo.ham@samsung.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/module.h>
14#include <linux/device.h>
15#include <linux/devfreq.h>
16#include "governor.h"
17
18static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
19 unsigned long *freq)
20{
21 struct devfreq_passive_data *p_data
22 = (struct devfreq_passive_data *)devfreq->data;
23 struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
24 unsigned long child_freq = ULONG_MAX;
25 struct dev_pm_opp *opp;
26 int i, count, ret = 0;
27
28 /*
29 * If the devfreq device with passive governor has the specific method
30 * to determine the next frequency, should use the get_target_freq()
31 * of struct devfreq_passive_data.
32 */
33 if (p_data->get_target_freq) {
34 ret = p_data->get_target_freq(devfreq, freq);
35 goto out;
36 }
37
38 /*
39 * If the parent and passive devfreq device uses the OPP table,
40 * get the next frequency by using the OPP table.
41 */
42
43 /*
44 * - parent devfreq device uses the governors except for passive.
45 * - passive devfreq device uses the passive governor.
46 *
47 * Each devfreq has the OPP table. After deciding the new frequency
48 * from the governor of parent devfreq device, the passive governor
49 * need to get the index of new frequency on OPP table of parent
50 * device. And then the index is used for getting the suitable
51 * new frequency for passive devfreq device.
52 */
53 if (!devfreq->profile || !devfreq->profile->freq_table
54 || devfreq->profile->max_state <= 0)
55 return -EINVAL;
56
57 /*
58 * The passive governor have to get the correct frequency from OPP
59 * list of parent device. Because in this case, *freq is temporary
60 * value which is decided by ondemand governor.
61 */
62 opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
63 if (IS_ERR(opp)) {
64 ret = PTR_ERR(opp);
65 goto out;
66 }
67
68 dev_pm_opp_put(opp);
69
70 /*
71 * Get the OPP table's index of decided freqeuncy by governor
72 * of parent device.
73 */
74 for (i = 0; i < parent_devfreq->profile->max_state; i++)
75 if (parent_devfreq->profile->freq_table[i] == *freq)
76 break;
77
78 if (i == parent_devfreq->profile->max_state) {
79 ret = -EINVAL;
80 goto out;
81 }
82
83 /* Get the suitable frequency by using index of parent device. */
84 if (i < devfreq->profile->max_state) {
85 child_freq = devfreq->profile->freq_table[i];
86 } else {
87 count = devfreq->profile->max_state;
88 child_freq = devfreq->profile->freq_table[count - 1];
89 }
90
91 /* Return the suitable frequency for passive device. */
92 *freq = child_freq;
93
94out:
95 return ret;
96}
97
98static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
99{
100 int ret;
101
102 if (!devfreq->governor)
103 return -EINVAL;
104
105 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
106
107 ret = devfreq->governor->get_target_freq(devfreq, &freq);
108 if (ret < 0)
109 goto out;
110
111 ret = devfreq->profile->target(devfreq->dev.parent, &freq, 0);
112 if (ret < 0)
113 goto out;
114
115 if (devfreq->profile->freq_table
116 && (devfreq_update_status(devfreq, freq)))
117 dev_err(&devfreq->dev,
118 "Couldn't update frequency transition information.\n");
119
120 devfreq->previous_freq = freq;
121
122out:
123 mutex_unlock(&devfreq->lock);
124
125 return 0;
126}
127
128static int devfreq_passive_notifier_call(struct notifier_block *nb,
129 unsigned long event, void *ptr)
130{
131 struct devfreq_passive_data *data
132 = container_of(nb, struct devfreq_passive_data, nb);
133 struct devfreq *devfreq = (struct devfreq *)data->this;
134 struct devfreq *parent = (struct devfreq *)data->parent;
135 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
136 unsigned long freq = freqs->new;
137
138 switch (event) {
139 case DEVFREQ_PRECHANGE:
140 if (parent->previous_freq > freq)
141 update_devfreq_passive(devfreq, freq);
142 break;
143 case DEVFREQ_POSTCHANGE:
144 if (parent->previous_freq < freq)
145 update_devfreq_passive(devfreq, freq);
146 break;
147 }
148
149 return NOTIFY_DONE;
150}
151
152static int devfreq_passive_event_handler(struct devfreq *devfreq,
153 unsigned int event, void *data)
154{
155 struct device *dev = devfreq->dev.parent;
156 struct devfreq_passive_data *p_data
157 = (struct devfreq_passive_data *)devfreq->data;
158 struct devfreq *parent = (struct devfreq *)p_data->parent;
159 struct notifier_block *nb = &p_data->nb;
160 int ret = 0;
161
162 if (!parent)
163 return -EPROBE_DEFER;
164
165 switch (event) {
166 case DEVFREQ_GOV_START:
167 if (!p_data->this)
168 p_data->this = devfreq;
169
170 nb->notifier_call = devfreq_passive_notifier_call;
171 ret = devm_devfreq_register_notifier(dev, parent, nb,
172 DEVFREQ_TRANSITION_NOTIFIER);
173 break;
174 case DEVFREQ_GOV_STOP:
175 devm_devfreq_unregister_notifier(dev, parent, nb,
176 DEVFREQ_TRANSITION_NOTIFIER);
177 break;
178 default:
179 break;
180 }
181
182 return ret;
183}
184
185static struct devfreq_governor devfreq_passive = {
186 .name = DEVFREQ_GOV_PASSIVE,
187 .immutable = 1,
188 .get_target_freq = devfreq_passive_get_target_freq,
189 .event_handler = devfreq_passive_event_handler,
190};
191
192static int __init devfreq_passive_init(void)
193{
194 return devfreq_add_governor(&devfreq_passive);
195}
196subsys_initcall(devfreq_passive_init);
197
198static void __exit devfreq_passive_exit(void)
199{
200 int ret;
201
202 ret = devfreq_remove_governor(&devfreq_passive);
203 if (ret)
204 pr_err("%s: failed remove governor %d\n", __func__, ret);
205}
206module_exit(devfreq_passive_exit);
207
208MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
209MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
210MODULE_DESCRIPTION("DEVFREQ Passive governor");
211MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/drivers/devfreq/governor_passive.c
4 *
5 * Copyright (C) 2016 Samsung Electronics
6 * Author: Chanwoo Choi <cw00.choi@samsung.com>
7 * Author: MyungJoo Ham <myungjoo.ham@samsung.com>
8 */
9
10#include <linux/module.h>
11#include <linux/device.h>
12#include <linux/devfreq.h>
13#include "governor.h"
14
15static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
16 unsigned long *freq)
17{
18 struct devfreq_passive_data *p_data
19 = (struct devfreq_passive_data *)devfreq->data;
20 struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
21 unsigned long child_freq = ULONG_MAX;
22 struct dev_pm_opp *opp, *p_opp;
23 int i, count;
24
25 /*
26 * If the devfreq device with passive governor has the specific method
27 * to determine the next frequency, should use the get_target_freq()
28 * of struct devfreq_passive_data.
29 */
30 if (p_data->get_target_freq)
31 return p_data->get_target_freq(devfreq, freq);
32
33 /*
34 * If the parent and passive devfreq device uses the OPP table,
35 * get the next frequency by using the OPP table.
36 */
37
38 /*
39 * - parent devfreq device uses the governors except for passive.
40 * - passive devfreq device uses the passive governor.
41 *
42 * Each devfreq has the OPP table. After deciding the new frequency
43 * from the governor of parent devfreq device, the passive governor
44 * need to get the index of new frequency on OPP table of parent
45 * device. And then the index is used for getting the suitable
46 * new frequency for passive devfreq device.
47 */
48 if (!devfreq->profile || !devfreq->profile->freq_table
49 || devfreq->profile->max_state <= 0)
50 return -EINVAL;
51
52 /*
53 * The passive governor have to get the correct frequency from OPP
54 * list of parent device. Because in this case, *freq is temporary
55 * value which is decided by ondemand governor.
56 */
57 if (devfreq->opp_table && parent_devfreq->opp_table) {
58 p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent,
59 freq, 0);
60 if (IS_ERR(p_opp))
61 return PTR_ERR(p_opp);
62
63 opp = dev_pm_opp_xlate_required_opp(parent_devfreq->opp_table,
64 devfreq->opp_table, p_opp);
65 dev_pm_opp_put(p_opp);
66
67 if (IS_ERR(opp))
68 goto no_required_opp;
69
70 *freq = dev_pm_opp_get_freq(opp);
71 dev_pm_opp_put(opp);
72
73 return 0;
74 }
75
76no_required_opp:
77 /*
78 * Get the OPP table's index of decided frequency by governor
79 * of parent device.
80 */
81 for (i = 0; i < parent_devfreq->profile->max_state; i++)
82 if (parent_devfreq->profile->freq_table[i] == *freq)
83 break;
84
85 if (i == parent_devfreq->profile->max_state)
86 return -EINVAL;
87
88 /* Get the suitable frequency by using index of parent device. */
89 if (i < devfreq->profile->max_state) {
90 child_freq = devfreq->profile->freq_table[i];
91 } else {
92 count = devfreq->profile->max_state;
93 child_freq = devfreq->profile->freq_table[count - 1];
94 }
95
96 /* Return the suitable frequency for passive device. */
97 *freq = child_freq;
98
99 return 0;
100}
101
102static int devfreq_passive_notifier_call(struct notifier_block *nb,
103 unsigned long event, void *ptr)
104{
105 struct devfreq_passive_data *data
106 = container_of(nb, struct devfreq_passive_data, nb);
107 struct devfreq *devfreq = (struct devfreq *)data->this;
108 struct devfreq *parent = (struct devfreq *)data->parent;
109 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
110 unsigned long freq = freqs->new;
111 int ret = 0;
112
113 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
114 switch (event) {
115 case DEVFREQ_PRECHANGE:
116 if (parent->previous_freq > freq)
117 ret = devfreq_update_target(devfreq, freq);
118
119 break;
120 case DEVFREQ_POSTCHANGE:
121 if (parent->previous_freq < freq)
122 ret = devfreq_update_target(devfreq, freq);
123 break;
124 }
125 mutex_unlock(&devfreq->lock);
126
127 if (ret < 0)
128 dev_warn(&devfreq->dev,
129 "failed to update devfreq using passive governor\n");
130
131 return NOTIFY_DONE;
132}
133
134static int devfreq_passive_event_handler(struct devfreq *devfreq,
135 unsigned int event, void *data)
136{
137 struct devfreq_passive_data *p_data
138 = (struct devfreq_passive_data *)devfreq->data;
139 struct devfreq *parent = (struct devfreq *)p_data->parent;
140 struct notifier_block *nb = &p_data->nb;
141 int ret = 0;
142
143 if (!parent)
144 return -EPROBE_DEFER;
145
146 switch (event) {
147 case DEVFREQ_GOV_START:
148 if (!p_data->this)
149 p_data->this = devfreq;
150
151 nb->notifier_call = devfreq_passive_notifier_call;
152 ret = devfreq_register_notifier(parent, nb,
153 DEVFREQ_TRANSITION_NOTIFIER);
154 break;
155 case DEVFREQ_GOV_STOP:
156 WARN_ON(devfreq_unregister_notifier(parent, nb,
157 DEVFREQ_TRANSITION_NOTIFIER));
158 break;
159 default:
160 break;
161 }
162
163 return ret;
164}
165
166static struct devfreq_governor devfreq_passive = {
167 .name = DEVFREQ_GOV_PASSIVE,
168 .flags = DEVFREQ_GOV_FLAG_IMMUTABLE,
169 .get_target_freq = devfreq_passive_get_target_freq,
170 .event_handler = devfreq_passive_event_handler,
171};
172
173static int __init devfreq_passive_init(void)
174{
175 return devfreq_add_governor(&devfreq_passive);
176}
177subsys_initcall(devfreq_passive_init);
178
179static void __exit devfreq_passive_exit(void)
180{
181 int ret;
182
183 ret = devfreq_remove_governor(&devfreq_passive);
184 if (ret)
185 pr_err("%s: failed remove governor %d\n", __func__, ret);
186}
187module_exit(devfreq_passive_exit);
188
189MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
190MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
191MODULE_DESCRIPTION("DEVFREQ Passive governor");
192MODULE_LICENSE("GPL v2");