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 int *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);
211 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
215 * devfreq_update_stats() - update the last_status pointer in struct devfreq
216 * @df: the devfreq instance whose status needs updating
218 * Governors are recommended to use this function along with last_status,
219 * which allows other entities to reuse the last_status without affecting
220 * the values fetched later by governors.
222 static inline int devfreq_update_stats(struct devfreq *df)
224 return df->profile->get_dev_status(df->dev.parent, &df->last_status);
227 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
229 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
230 * and devfreq_add_device
231 * @upthreshold: If the load is over this value, the frequency jumps.
232 * Specify 0 to use the default. Valid value = 0 to 100.
233 * @downdifferential: If the load is under upthreshold - downdifferential,
234 * the governor may consider slowing the frequency down.
235 * Specify 0 to use the default. Valid value = 0 to 100.
236 * downdifferential < upthreshold must hold.
238 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
239 * the governor uses the default values.
241 struct devfreq_simple_ondemand_data {
242 unsigned int upthreshold;
243 unsigned int downdifferential;
247 #else /* !CONFIG_PM_DEVFREQ */
248 static inline struct devfreq *devfreq_add_device(struct device *dev,
249 struct devfreq_dev_profile *profile,
250 const char *governor_name,
253 return ERR_PTR(-ENOSYS);
256 static inline int devfreq_remove_device(struct devfreq *devfreq)
261 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
262 struct devfreq_dev_profile *profile,
263 const char *governor_name,
266 return ERR_PTR(-ENOSYS);
269 static inline void devm_devfreq_remove_device(struct device *dev,
270 struct devfreq *devfreq)
274 static inline int devfreq_suspend_device(struct devfreq *devfreq)
279 static inline int devfreq_resume_device(struct devfreq *devfreq)
284 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
285 unsigned long *freq, u32 flags)
287 return ERR_PTR(-EINVAL);
290 static inline int devfreq_register_opp_notifier(struct device *dev,
291 struct devfreq *devfreq)
296 static inline int devfreq_unregister_opp_notifier(struct device *dev,
297 struct devfreq *devfreq)
302 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
303 struct devfreq *devfreq)
308 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
309 struct devfreq *devfreq)
313 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
316 return ERR_PTR(-ENODEV);
319 static inline int devfreq_update_stats(struct devfreq *df)
323 #endif /* CONFIG_PM_DEVFREQ */
325 #endif /* __LINUX_DEVFREQ_H__ */