2 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
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.
13 #ifndef __LINUX_DEVFREQ_H__
14 #define __LINUX_DEVFREQ_H__
16 #include <linux/device.h>
17 #include <linux/notifier.h>
18 #include <linux/pm_opp.h>
20 #define DEVFREQ_NAME_LEN 16
25 * struct devfreq_dev_status - Data given from devfreq user device to
26 * governors. Represents the performance
28 * @total_time: The total time represented by this instance of
30 * @busy_time: The time that the device was working among the
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.
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
;
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)
53 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1
56 * struct devfreq_dev_profile - Devfreq's user device profile
57 * @initial_freq: The operating frequency when devfreq_add_device() is
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. Governors are recommended not to
69 * use this directly. Instead, governors are recommended
70 * to use devfreq_update_stats() along with
71 * devfreq.last_status.
72 * @get_cur_freq: The device should provide the current frequency
73 * at which it is operating.
74 * @exit: An optional callback that is called when devfreq
75 * is removing the devfreq object due to error or
76 * from devfreq_remove_device() call. If the user
77 * has registered devfreq->nb at a notifier-head,
78 * this is the time to unregister it.
79 * @freq_table: Optional list of frequencies to support statistics.
80 * @max_state: The size of freq_table.
82 struct devfreq_dev_profile
{
83 unsigned long initial_freq
;
84 unsigned int polling_ms
;
86 int (*target
)(struct device
*dev
, unsigned long *freq
, u32 flags
);
87 int (*get_dev_status
)(struct device
*dev
,
88 struct devfreq_dev_status
*stat
);
89 int (*get_cur_freq
)(struct device
*dev
, unsigned long *freq
);
90 void (*exit
)(struct device
*dev
);
92 unsigned long *freq_table
;
93 unsigned int max_state
;
97 * struct devfreq_governor - Devfreq policy governor
98 * @node: list node - contains registered devfreq governors
99 * @name: Governor's name
100 * @get_target_freq: Returns desired operating frequency for the device.
101 * Basically, get_target_freq will run
102 * devfreq_dev_profile.get_dev_status() to get the
103 * status of the device (load = busy_time / total_time).
104 * If no_central_polling is set, this callback is called
105 * only with update_devfreq() notified by OPP.
106 * @event_handler: Callback for devfreq core framework to notify events
107 * to governors. Events include per device governor
108 * init and exit, opp changes out of devfreq, suspend
109 * and resume of per device devfreq during device idle.
111 * Note that the callbacks are called with devfreq->lock locked by devfreq.
113 struct devfreq_governor
{
114 struct list_head node
;
116 const char name
[DEVFREQ_NAME_LEN
];
117 int (*get_target_freq
)(struct devfreq
*this, unsigned long *freq
);
118 int (*event_handler
)(struct devfreq
*devfreq
,
119 unsigned int event
, void *data
);
123 * struct devfreq - Device devfreq structure
124 * @node: list node - contains the devices with devfreq that have been
126 * @lock: a mutex to protect accessing devfreq.
127 * @dev: device registered by devfreq class. dev.parent is the device
129 * @profile: device-specific devfreq profile
130 * @governor: method how to choose frequency based on the usage.
131 * @governor_name: devfreq governor name for use with this devfreq
132 * @nb: notifier block used to notify devfreq object that it should
133 * reevaluate operable frequencies. Devfreq users may use
134 * devfreq.nb to the corresponding register notifier call chain.
135 * @work: delayed work for load monitoring.
136 * @previous_freq: previously configured frequency value.
137 * @data: Private data of the governor. The devfreq framework does not
139 * @min_freq: Limit minimum frequency requested by user (0: none)
140 * @max_freq: Limit maximum frequency requested by user (0: none)
141 * @stop_polling: devfreq polling status of a device.
142 * @total_trans: Number of devfreq transitions
143 * @trans_table: Statistics of devfreq transitions
144 * @time_in_state: Statistics of devfreq states
145 * @last_stat_updated: The last time stat updated
147 * This structure stores the devfreq information for a give device.
149 * Note that when a governor accesses entries in struct devfreq in its
150 * functions except for the context of callbacks defined in struct
151 * devfreq_governor, the governor should protect its access with the
152 * struct mutex lock in struct devfreq. A governor may use this mutex
153 * to protect its own private data in void *data as well.
156 struct list_head node
;
160 struct devfreq_dev_profile
*profile
;
161 const struct devfreq_governor
*governor
;
162 char governor_name
[DEVFREQ_NAME_LEN
];
163 struct notifier_block nb
;
164 struct delayed_work work
;
166 unsigned long previous_freq
;
167 struct devfreq_dev_status last_status
;
169 void *data
; /* private data for governors */
171 unsigned long min_freq
;
172 unsigned long max_freq
;
175 /* information for device frequency transition */
176 unsigned int total_trans
;
177 unsigned int *trans_table
;
178 unsigned long *time_in_state
;
179 unsigned long last_stat_updated
;
182 #if defined(CONFIG_PM_DEVFREQ)
183 extern struct devfreq
*devfreq_add_device(struct device
*dev
,
184 struct devfreq_dev_profile
*profile
,
185 const char *governor_name
,
187 extern int devfreq_remove_device(struct devfreq
*devfreq
);
188 extern struct devfreq
*devm_devfreq_add_device(struct device
*dev
,
189 struct devfreq_dev_profile
*profile
,
190 const char *governor_name
,
192 extern void devm_devfreq_remove_device(struct device
*dev
,
193 struct devfreq
*devfreq
);
195 /* Supposed to be called by PM callbacks */
196 extern int devfreq_suspend_device(struct devfreq
*devfreq
);
197 extern int devfreq_resume_device(struct devfreq
*devfreq
);
199 /* Helper functions for devfreq user device driver with OPP. */
200 extern struct dev_pm_opp
*devfreq_recommended_opp(struct device
*dev
,
201 unsigned long *freq
, u32 flags
);
202 extern int devfreq_register_opp_notifier(struct device
*dev
,
203 struct devfreq
*devfreq
);
204 extern int devfreq_unregister_opp_notifier(struct device
*dev
,
205 struct devfreq
*devfreq
);
206 extern int devm_devfreq_register_opp_notifier(struct device
*dev
,
207 struct devfreq
*devfreq
);
208 extern void devm_devfreq_unregister_opp_notifier(struct device
*dev
,
209 struct devfreq
*devfreq
);
212 * devfreq_update_stats() - update the last_status pointer in struct devfreq
213 * @df: the devfreq instance whose status needs updating
215 * Governors are recommended to use this function along with last_status,
216 * which allows other entities to reuse the last_status without affecting
217 * the values fetched later by governors.
219 static inline int devfreq_update_stats(struct devfreq
*df
)
221 return df
->profile
->get_dev_status(df
->dev
.parent
, &df
->last_status
);
224 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
226 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
227 * and devfreq_add_device
228 * @upthreshold: If the load is over this value, the frequency jumps.
229 * Specify 0 to use the default. Valid value = 0 to 100.
230 * @downdifferential: If the load is under upthreshold - downdifferential,
231 * the governor may consider slowing the frequency down.
232 * Specify 0 to use the default. Valid value = 0 to 100.
233 * downdifferential < upthreshold must hold.
235 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
236 * the governor uses the default values.
238 struct devfreq_simple_ondemand_data
{
239 unsigned int upthreshold
;
240 unsigned int downdifferential
;
244 #else /* !CONFIG_PM_DEVFREQ */
245 static inline struct devfreq
*devfreq_add_device(struct device
*dev
,
246 struct devfreq_dev_profile
*profile
,
247 const char *governor_name
,
250 return ERR_PTR(-ENOSYS
);
253 static inline int devfreq_remove_device(struct devfreq
*devfreq
)
258 static inline struct devfreq
*devm_devfreq_add_device(struct device
*dev
,
259 struct devfreq_dev_profile
*profile
,
260 const char *governor_name
,
263 return ERR_PTR(-ENOSYS
);
266 static inline void devm_devfreq_remove_device(struct device
*dev
,
267 struct devfreq
*devfreq
)
271 static inline int devfreq_suspend_device(struct devfreq
*devfreq
)
276 static inline int devfreq_resume_device(struct devfreq
*devfreq
)
281 static inline struct dev_pm_opp
*devfreq_recommended_opp(struct device
*dev
,
282 unsigned long *freq
, u32 flags
)
284 return ERR_PTR(-EINVAL
);
287 static inline int devfreq_register_opp_notifier(struct device
*dev
,
288 struct devfreq
*devfreq
)
293 static inline int devfreq_unregister_opp_notifier(struct device
*dev
,
294 struct devfreq
*devfreq
)
299 static inline int devm_devfreq_register_opp_notifier(struct device
*dev
,
300 struct devfreq
*devfreq
)
305 static inline void devm_devfreq_unregister_opp_notifier(struct device
*dev
,
306 struct devfreq
*devfreq
)
310 static inline int devfreq_update_stats(struct devfreq
*df
)
314 #endif /* CONFIG_PM_DEVFREQ */
316 #endif /* __LINUX_DEVFREQ_H__ */