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Linux/include/linux/devfreq.h

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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/pm_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. 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.
 81  */
 82 struct devfreq_dev_profile {
 83         unsigned long initial_freq;
 84         unsigned int polling_ms;
 85 
 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);
 91 
 92         unsigned long *freq_table;
 93         unsigned int max_state;
 94 };
 95 
 96 /**
 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.
110  *
111  * Note that the callbacks are called with devfreq->lock locked by devfreq.
112  */
113 struct devfreq_governor {
114         struct list_head node;
115 
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);
120 };
121 
122 /**
123  * struct devfreq - Device devfreq structure
124  * @node:       list node - contains the devices with devfreq that have been
125  *              registered.
126  * @lock:       a mutex to protect accessing devfreq.
127  * @dev:        device registered by devfreq class. dev.parent is the device
128  *              using devfreq.
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
138  *              touch this.
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
146  *
147  * This structure stores the devfreq information for a give device.
148  *
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.
154  */
155 struct devfreq {
156         struct list_head node;
157 
158         struct mutex lock;
159         struct device dev;
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;
165 
166         unsigned long previous_freq;
167         struct devfreq_dev_status last_status;
168 
169         void *data; /* private data for governors */
170 
171         unsigned long min_freq;
172         unsigned long max_freq;
173         bool stop_polling;
174 
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;
180 };
181 
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,
186                                   void *data);
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,
191                                   void *data);
192 extern void devm_devfreq_remove_device(struct device *dev,
193                                   struct devfreq *devfreq);
194 
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);
198 
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);
210 
211 /**
212  * devfreq_update_stats() - update the last_status pointer in struct devfreq
213  * @df:         the devfreq instance whose status needs updating
214  *
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.
218  */
219 static inline int devfreq_update_stats(struct devfreq *df)
220 {
221         return df->profile->get_dev_status(df->dev.parent, &df->last_status);
222 }
223 
224 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
225 /**
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.
234  *
235  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
236  * the governor uses the default values.
237  */
238 struct devfreq_simple_ondemand_data {
239         unsigned int upthreshold;
240         unsigned int downdifferential;
241 };
242 #endif
243 
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,
248                                           void *data)
249 {
250         return ERR_PTR(-ENOSYS);
251 }
252 
253 static inline int devfreq_remove_device(struct devfreq *devfreq)
254 {
255         return 0;
256 }
257 
258 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
259                                         struct devfreq_dev_profile *profile,
260                                         const char *governor_name,
261                                         void *data)
262 {
263         return ERR_PTR(-ENOSYS);
264 }
265 
266 static inline void devm_devfreq_remove_device(struct device *dev,
267                                         struct devfreq *devfreq)
268 {
269 }
270 
271 static inline int devfreq_suspend_device(struct devfreq *devfreq)
272 {
273         return 0;
274 }
275 
276 static inline int devfreq_resume_device(struct devfreq *devfreq)
277 {
278         return 0;
279 }
280 
281 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
282                                            unsigned long *freq, u32 flags)
283 {
284         return ERR_PTR(-EINVAL);
285 }
286 
287 static inline int devfreq_register_opp_notifier(struct device *dev,
288                                          struct devfreq *devfreq)
289 {
290         return -EINVAL;
291 }
292 
293 static inline int devfreq_unregister_opp_notifier(struct device *dev,
294                                            struct devfreq *devfreq)
295 {
296         return -EINVAL;
297 }
298 
299 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
300                                                      struct devfreq *devfreq)
301 {
302         return -EINVAL;
303 }
304 
305 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
306                                                         struct devfreq *devfreq)
307 {
308 }
309 
310 static inline int devfreq_update_stats(struct devfreq *df)
311 {
312         return -EINVAL;
313 }
314 #endif /* CONFIG_PM_DEVFREQ */
315 
316 #endif /* __LINUX_DEVFREQ_H__ */
317 

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