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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_data; |
45 | }; |
46 | |
47 | /* |
48 | * The resulting frequency should be at most this. (this bound is the |
49 | * least upper bound; thus, the resulting freq should be lower or same) |
50 | * If the flag is not set, the resulting frequency should be at most the |
51 | * bound (greatest lower bound) |
52 | */ |
53 | #define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1 |
54 | |
55 | /** |
56 | * struct devfreq_dev_profile - Devfreq's user device profile |
57 | * @initial_freq: The operating frequency when devfreq_add_device() is |
58 | * called. |
59 | * @polling_ms: The polling interval in ms. 0 disables polling. |
60 | * @target: The device should set its operating frequency at |
61 | * freq or lowest-upper-than-freq value. If freq is |
62 | * higher than any operable frequency, set maximum. |
63 | * Before returning, target function should set |
64 | * freq at the current frequency. |
65 | * The "flags" parameter's possible values are |
66 | * explained above with "DEVFREQ_FLAG_*" macros. |
67 | * @get_dev_status: The device should provide the current performance |
68 | * status to devfreq, which is used by governors. |
69 | * @get_cur_freq: The device should provide the current frequency |
70 | * at which it is operating. |
71 | * @exit: An optional callback that is called when devfreq |
72 | * is removing the devfreq object due to error or |
73 | * from devfreq_remove_device() call. If the user |
74 | * has registered devfreq->nb at a notifier-head, |
75 | * this is the time to unregister it. |
76 | * @freq_table: Optional list of frequencies to support statistics. |
77 | * @max_state: The size of freq_table. |
78 | */ |
79 | struct devfreq_dev_profile { |
80 | unsigned long initial_freq; |
81 | unsigned int polling_ms; |
82 | |
83 | int (*target)(struct device *dev, unsigned long *freq, u32 flags); |
84 | int (*get_dev_status)(struct device *dev, |
85 | struct devfreq_dev_status *stat); |
86 | int (*get_cur_freq)(struct device *dev, unsigned long *freq); |
87 | void (*exit)(struct device *dev); |
88 | |
89 | unsigned int *freq_table; |
90 | unsigned int max_state; |
91 | }; |
92 | |
93 | /** |
94 | * struct devfreq_governor - Devfreq policy governor |
95 | * @node: list node - contains registered devfreq governors |
96 | * @name: Governor's name |
97 | * @get_target_freq: Returns desired operating frequency for the device. |
98 | * Basically, get_target_freq will run |
99 | * devfreq_dev_profile.get_dev_status() to get the |
100 | * status of the device (load = busy_time / total_time). |
101 | * If no_central_polling is set, this callback is called |
102 | * only with update_devfreq() notified by OPP. |
103 | * @event_handler: Callback for devfreq core framework to notify events |
104 | * to governors. Events include per device governor |
105 | * init and exit, opp changes out of devfreq, suspend |
106 | * and resume of per device devfreq during device idle. |
107 | * |
108 | * Note that the callbacks are called with devfreq->lock locked by devfreq. |
109 | */ |
110 | struct devfreq_governor { |
111 | struct list_head node; |
112 | |
113 | const char name[DEVFREQ_NAME_LEN]; |
114 | int (*get_target_freq)(struct devfreq *this, unsigned long *freq); |
115 | int (*event_handler)(struct devfreq *devfreq, |
116 | unsigned int event, void *data); |
117 | }; |
118 | |
119 | /** |
120 | * struct devfreq - Device devfreq structure |
121 | * @node: list node - contains the devices with devfreq that have been |
122 | * registered. |
123 | * @lock: a mutex to protect accessing devfreq. |
124 | * @dev: device registered by devfreq class. dev.parent is the device |
125 | * using devfreq. |
126 | * @profile: device-specific devfreq profile |
127 | * @governor: method how to choose frequency based on the usage. |
128 | * @governor_name: devfreq governor name for use with this devfreq |
129 | * @nb: notifier block used to notify devfreq object that it should |
130 | * reevaluate operable frequencies. Devfreq users may use |
131 | * devfreq.nb to the corresponding register notifier call chain. |
132 | * @work: delayed work for load monitoring. |
133 | * @previous_freq: previously configured frequency value. |
134 | * @data: Private data of the governor. The devfreq framework does not |
135 | * touch this. |
136 | * @min_freq: Limit minimum frequency requested by user (0: none) |
137 | * @max_freq: Limit maximum frequency requested by user (0: none) |
138 | * @stop_polling: devfreq polling status of a device. |
139 | * @total_trans: Number of devfreq transitions |
140 | * @trans_table: Statistics of devfreq transitions |
141 | * @time_in_state: Statistics of devfreq states |
142 | * @last_stat_updated: The last time stat updated |
143 | * |
144 | * This structure stores the devfreq information for a give device. |
145 | * |
146 | * Note that when a governor accesses entries in struct devfreq in its |
147 | * functions except for the context of callbacks defined in struct |
148 | * devfreq_governor, the governor should protect its access with the |
149 | * struct mutex lock in struct devfreq. A governor may use this mutex |
150 | * to protect its own private data in void *data as well. |
151 | */ |
152 | struct devfreq { |
153 | struct list_head node; |
154 | |
155 | struct mutex lock; |
156 | struct device dev; |
157 | struct devfreq_dev_profile *profile; |
158 | const struct devfreq_governor *governor; |
159 | char governor_name[DEVFREQ_NAME_LEN]; |
160 | struct notifier_block nb; |
161 | struct delayed_work work; |
162 | |
163 | unsigned long previous_freq; |
164 | |
165 | void *data; /* private data for governors */ |
166 | |
167 | unsigned long min_freq; |
168 | unsigned long max_freq; |
169 | bool stop_polling; |
170 | |
171 | /* information for device freqeuncy transition */ |
172 | unsigned int total_trans; |
173 | unsigned int *trans_table; |
174 | unsigned long *time_in_state; |
175 | unsigned long last_stat_updated; |
176 | }; |
177 | |
178 | #if defined(CONFIG_PM_DEVFREQ) |
179 | extern struct devfreq *devfreq_add_device(struct device *dev, |
180 | struct devfreq_dev_profile *profile, |
181 | const char *governor_name, |
182 | void *data); |
183 | extern int devfreq_remove_device(struct devfreq *devfreq); |
184 | extern int devfreq_suspend_device(struct devfreq *devfreq); |
185 | extern int devfreq_resume_device(struct devfreq *devfreq); |
186 | |
187 | /* Helper functions for devfreq user device driver with OPP. */ |
188 | extern struct opp *devfreq_recommended_opp(struct device *dev, |
189 | unsigned long *freq, u32 flags); |
190 | extern int devfreq_register_opp_notifier(struct device *dev, |
191 | struct devfreq *devfreq); |
192 | extern int devfreq_unregister_opp_notifier(struct device *dev, |
193 | struct devfreq *devfreq); |
194 | |
195 | #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) |
196 | /** |
197 | * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq |
198 | * and devfreq_add_device |
199 | * @upthreshold: If the load is over this value, the frequency jumps. |
200 | * Specify 0 to use the default. Valid value = 0 to 100. |
201 | * @downdifferential: If the load is under upthreshold - downdifferential, |
202 | * the governor may consider slowing the frequency down. |
203 | * Specify 0 to use the default. Valid value = 0 to 100. |
204 | * downdifferential < upthreshold must hold. |
205 | * |
206 | * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor, |
207 | * the governor uses the default values. |
208 | */ |
209 | struct devfreq_simple_ondemand_data { |
210 | unsigned int upthreshold; |
211 | unsigned int downdifferential; |
212 | }; |
213 | #endif |
214 | |
215 | #else /* !CONFIG_PM_DEVFREQ */ |
216 | static inline struct devfreq *devfreq_add_device(struct device *dev, |
217 | struct devfreq_dev_profile *profile, |
218 | const char *governor_name, |
219 | void *data) |
220 | { |
221 | return NULL; |
222 | } |
223 | |
224 | static inline int devfreq_remove_device(struct devfreq *devfreq) |
225 | { |
226 | return 0; |
227 | } |
228 | |
229 | static inline int devfreq_suspend_device(struct devfreq *devfreq) |
230 | { |
231 | return 0; |
232 | } |
233 | |
234 | static inline int devfreq_resume_device(struct devfreq *devfreq) |
235 | { |
236 | return 0; |
237 | } |
238 | |
239 | static inline struct opp *devfreq_recommended_opp(struct device *dev, |
240 | unsigned long *freq, u32 flags) |
241 | { |
242 | return ERR_PTR(-EINVAL); |
243 | } |
244 | |
245 | static inline int devfreq_register_opp_notifier(struct device *dev, |
246 | struct devfreq *devfreq) |
247 | { |
248 | return -EINVAL; |
249 | } |
250 | |
251 | static inline int devfreq_unregister_opp_notifier(struct device *dev, |
252 | struct devfreq *devfreq) |
253 | { |
254 | return -EINVAL; |
255 | } |
256 | |
257 | #endif /* CONFIG_PM_DEVFREQ */ |
258 | |
259 | #endif /* __LINUX_DEVFREQ_H__ */ |
260 |
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