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99613311 CC |
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 | ||
18 | static 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 | rcu_read_lock(); | |
63 | opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0); | |
64 | rcu_read_unlock(); | |
65 | if (IS_ERR(opp)) { | |
66 | ret = PTR_ERR(opp); | |
67 | goto out; | |
68 | } | |
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 | ||
94 | out: | |
95 | return ret; | |
96 | } | |
97 | ||
98 | static 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 | devfreq->previous_freq = freq; | |
116 | ||
117 | out: | |
118 | mutex_unlock(&devfreq->lock); | |
119 | ||
120 | return 0; | |
121 | } | |
122 | ||
123 | static int devfreq_passive_notifier_call(struct notifier_block *nb, | |
124 | unsigned long event, void *ptr) | |
125 | { | |
126 | struct devfreq_passive_data *data | |
127 | = container_of(nb, struct devfreq_passive_data, nb); | |
128 | struct devfreq *devfreq = (struct devfreq *)data->this; | |
129 | struct devfreq *parent = (struct devfreq *)data->parent; | |
130 | struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr; | |
131 | unsigned long freq = freqs->new; | |
132 | ||
133 | switch (event) { | |
134 | case DEVFREQ_PRECHANGE: | |
135 | if (parent->previous_freq > freq) | |
136 | update_devfreq_passive(devfreq, freq); | |
137 | break; | |
138 | case DEVFREQ_POSTCHANGE: | |
139 | if (parent->previous_freq < freq) | |
140 | update_devfreq_passive(devfreq, freq); | |
141 | break; | |
142 | } | |
143 | ||
144 | return NOTIFY_DONE; | |
145 | } | |
146 | ||
147 | static int devfreq_passive_event_handler(struct devfreq *devfreq, | |
148 | unsigned int event, void *data) | |
149 | { | |
150 | struct device *dev = devfreq->dev.parent; | |
151 | struct devfreq_passive_data *p_data | |
152 | = (struct devfreq_passive_data *)devfreq->data; | |
153 | struct devfreq *parent = (struct devfreq *)p_data->parent; | |
154 | struct notifier_block *nb = &p_data->nb; | |
155 | int ret = 0; | |
156 | ||
157 | if (!parent) | |
158 | return -EPROBE_DEFER; | |
159 | ||
160 | switch (event) { | |
161 | case DEVFREQ_GOV_START: | |
162 | if (!p_data->this) | |
163 | p_data->this = devfreq; | |
164 | ||
165 | nb->notifier_call = devfreq_passive_notifier_call; | |
166 | ret = devm_devfreq_register_notifier(dev, parent, nb, | |
167 | DEVFREQ_TRANSITION_NOTIFIER); | |
168 | break; | |
169 | case DEVFREQ_GOV_STOP: | |
170 | devm_devfreq_unregister_notifier(dev, parent, nb, | |
171 | DEVFREQ_TRANSITION_NOTIFIER); | |
172 | break; | |
173 | default: | |
174 | break; | |
175 | } | |
176 | ||
177 | return ret; | |
178 | } | |
179 | ||
180 | static struct devfreq_governor devfreq_passive = { | |
181 | .name = "passive", | |
182 | .get_target_freq = devfreq_passive_get_target_freq, | |
183 | .event_handler = devfreq_passive_event_handler, | |
184 | }; | |
185 | ||
186 | static int __init devfreq_passive_init(void) | |
187 | { | |
188 | return devfreq_add_governor(&devfreq_passive); | |
189 | } | |
190 | subsys_initcall(devfreq_passive_init); | |
191 | ||
192 | static void __exit devfreq_passive_exit(void) | |
193 | { | |
194 | int ret; | |
195 | ||
196 | ret = devfreq_remove_governor(&devfreq_passive); | |
197 | if (ret) | |
198 | pr_err("%s: failed remove governor %d\n", __func__, ret); | |
99613311 CC |
199 | } |
200 | module_exit(devfreq_passive_exit); | |
201 | ||
202 | MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>"); | |
203 | MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); | |
204 | MODULE_DESCRIPTION("DEVFREQ Passive governor"); | |
205 | MODULE_LICENSE("GPL v2"); |