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1 | /* |
2 | * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework | |
3 | * for Non-CPU Devices. | |
4 | * | |
5 | * Copyright (C) 2011 Samsung Electronics | |
6 | * 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 | #ifndef __LINUX_DEVFREQ_H__ | |
14 | #define __LINUX_DEVFREQ_H__ | |
15 | ||
16 | #include <linux/device.h> | |
17 | #include <linux/notifier.h> | |
18 | #include <linux/opp.h> | |
19 | ||
20 | #define DEVFREQ_NAME_LEN 16 | |
21 | ||
22 | struct devfreq; | |
23 | ||
24 | /** | |
25 | * struct devfreq_dev_status - Data given from devfreq user device to | |
26 | * governors. Represents the performance | |
27 | * statistics. | |
28 | * @total_time The total time represented by this instance of | |
29 | * devfreq_dev_status | |
30 | * @busy_time The time that the device was working among the | |
31 | * total_time. | |
32 | * @current_frequency The operating frequency. | |
33 | * @private_data An entry not specified by the devfreq framework. | |
34 | * A device and a specific governor may have their | |
35 | * own protocol with private_data. However, because | |
36 | * this is governor-specific, a governor using this | |
37 | * will be only compatible with devices aware of it. | |
38 | */ | |
39 | struct devfreq_dev_status { | |
40 | /* both since the last measure */ | |
41 | unsigned long total_time; | |
42 | unsigned long busy_time; | |
43 | unsigned long current_frequency; | |
44 | void *private_date; | |
45 | }; | |
46 | ||
47 | /** | |
48 | * struct devfreq_dev_profile - Devfreq's user device profile | |
49 | * @initial_freq The operating frequency when devfreq_add_device() is | |
50 | * called. | |
51 | * @polling_ms The polling interval in ms. 0 disables polling. | |
52 | * @target The device should set its operating frequency at | |
53 | * freq or lowest-upper-than-freq value. If freq is | |
54 | * higher than any operable frequency, set maximum. | |
55 | * Before returning, target function should set | |
56 | * freq at the current frequency. | |
57 | * @get_dev_status The device should provide the current performance | |
58 | * status to devfreq, which is used by governors. | |
59 | * @exit An optional callback that is called when devfreq | |
60 | * is removing the devfreq object due to error or | |
61 | * from devfreq_remove_device() call. If the user | |
62 | * has registered devfreq->nb at a notifier-head, | |
63 | * this is the time to unregister it. | |
64 | */ | |
65 | struct devfreq_dev_profile { | |
66 | unsigned long initial_freq; | |
67 | unsigned int polling_ms; | |
68 | ||
69 | int (*target)(struct device *dev, unsigned long *freq); | |
70 | int (*get_dev_status)(struct device *dev, | |
71 | struct devfreq_dev_status *stat); | |
72 | void (*exit)(struct device *dev); | |
73 | }; | |
74 | ||
75 | /** | |
76 | * struct devfreq_governor - Devfreq policy governor | |
77 | * @name Governor's name | |
78 | * @get_target_freq Returns desired operating frequency for the device. | |
79 | * Basically, get_target_freq will run | |
80 | * devfreq_dev_profile.get_dev_status() to get the | |
81 | * status of the device (load = busy_time / total_time). | |
82 | * If no_central_polling is set, this callback is called | |
83 | * only with update_devfreq() notified by OPP. | |
84 | * @init Called when the devfreq is being attached to a device | |
85 | * @exit Called when the devfreq is being removed from a | |
86 | * device. Governor should stop any internal routines | |
87 | * before return because related data may be | |
88 | * freed after exit(). | |
89 | * @no_central_polling Do not use devfreq's central polling mechanism. | |
90 | * When this is set, devfreq will not call | |
91 | * get_target_freq with devfreq_monitor(). However, | |
92 | * devfreq will call get_target_freq with | |
93 | * devfreq_update() notified by OPP framework. | |
94 | * | |
95 | * Note that the callbacks are called with devfreq->lock locked by devfreq. | |
96 | */ | |
97 | struct devfreq_governor { | |
98 | const char name[DEVFREQ_NAME_LEN]; | |
99 | int (*get_target_freq)(struct devfreq *this, unsigned long *freq); | |
100 | int (*init)(struct devfreq *this); | |
101 | void (*exit)(struct devfreq *this); | |
102 | const bool no_central_polling; | |
103 | }; | |
104 | ||
105 | /** | |
106 | * struct devfreq - Device devfreq structure | |
107 | * @node list node - contains the devices with devfreq that have been | |
108 | * registered. | |
109 | * @lock a mutex to protect accessing devfreq. | |
110 | * @dev device registered by devfreq class. dev.parent is the device | |
111 | * using devfreq. | |
112 | * @profile device-specific devfreq profile | |
113 | * @governor method how to choose frequency based on the usage. | |
114 | * @nb notifier block used to notify devfreq object that it should | |
115 | * reevaluate operable frequencies. Devfreq users may use | |
116 | * devfreq.nb to the corresponding register notifier call chain. | |
117 | * @polling_jiffies interval in jiffies. | |
118 | * @previous_freq previously configured frequency value. | |
119 | * @next_polling the number of remaining jiffies to poll with | |
120 | * "devfreq_monitor" executions to reevaluate | |
121 | * frequency/voltage of the device. Set by | |
122 | * profile's polling_ms interval. | |
123 | * @data Private data of the governor. The devfreq framework does not | |
124 | * touch this. | |
125 | * @being_removed a flag to mark that this object is being removed in | |
126 | * order to prevent trying to remove the object multiple times. | |
127 | * | |
128 | * This structure stores the devfreq information for a give device. | |
129 | * | |
130 | * Note that when a governor accesses entries in struct devfreq in its | |
131 | * functions except for the context of callbacks defined in struct | |
132 | * devfreq_governor, the governor should protect its access with the | |
133 | * struct mutex lock in struct devfreq. A governor may use this mutex | |
134 | * to protect its own private data in void *data as well. | |
135 | */ | |
136 | struct devfreq { | |
137 | struct list_head node; | |
138 | ||
139 | struct mutex lock; | |
140 | struct device dev; | |
141 | struct devfreq_dev_profile *profile; | |
142 | const struct devfreq_governor *governor; | |
143 | struct notifier_block nb; | |
144 | ||
145 | unsigned long polling_jiffies; | |
146 | unsigned long previous_freq; | |
147 | unsigned int next_polling; | |
148 | ||
149 | void *data; /* private data for governors */ | |
150 | ||
151 | bool being_removed; | |
152 | }; | |
153 | ||
154 | #if defined(CONFIG_PM_DEVFREQ) | |
155 | extern struct devfreq *devfreq_add_device(struct device *dev, | |
156 | struct devfreq_dev_profile *profile, | |
157 | const struct devfreq_governor *governor, | |
158 | void *data); | |
159 | extern int devfreq_remove_device(struct devfreq *devfreq); | |
160 | ||
161 | /* Helper functions for devfreq user device driver with OPP. */ | |
162 | extern struct opp *devfreq_recommended_opp(struct device *dev, | |
163 | unsigned long *freq); | |
164 | extern int devfreq_register_opp_notifier(struct device *dev, | |
165 | struct devfreq *devfreq); | |
166 | extern int devfreq_unregister_opp_notifier(struct device *dev, | |
167 | struct devfreq *devfreq); | |
168 | ||
169 | #else /* !CONFIG_PM_DEVFREQ */ | |
170 | static struct devfreq *devfreq_add_device(struct device *dev, | |
171 | struct devfreq_dev_profile *profile, | |
172 | struct devfreq_governor *governor, | |
173 | void *data); | |
174 | { | |
175 | return NULL; | |
176 | } | |
177 | ||
178 | static int devfreq_remove_device(struct devfreq *devfreq); | |
179 | { | |
180 | return 0; | |
181 | } | |
182 | ||
183 | static struct opp *devfreq_recommended_opp(struct device *dev, | |
184 | unsigned long *freq) | |
185 | { | |
186 | return -EINVAL; | |
187 | } | |
188 | ||
189 | static int devfreq_register_opp_notifier(struct device *dev, | |
190 | struct devfreq *devfreq) | |
191 | { | |
192 | return -EINVAL; | |
193 | } | |
194 | ||
195 | static int devfreq_unregister_opp_notifier(struct device *dev, | |
196 | struct devfreq *devfreq) | |
197 | { | |
198 | return -EINVAL; | |
199 | } | |
200 | ||
201 | #endif /* CONFIG_PM_DEVFREQ */ | |
202 | ||
203 | #endif /* __LINUX_DEVFREQ_H__ */ |