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TOMOYO Linux Cross Reference
Linux/include/linux/devfreq.h

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  1 /* SPDX-License-Identifier: GPL-2.0-only */
  2 /*
  3  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
  4  *          for Non-CPU Devices.
  5  *
  6  * Copyright (C) 2011 Samsung Electronics
  7  *      MyungJoo Ham <myungjoo.ham@samsung.com>
  8  */
  9 
 10 #ifndef __LINUX_DEVFREQ_H__
 11 #define __LINUX_DEVFREQ_H__
 12 
 13 #include <linux/device.h>
 14 #include <linux/notifier.h>
 15 #include <linux/pm_opp.h>
 16 
 17 #define DEVFREQ_NAME_LEN 16
 18 
 19 /* DEVFREQ governor name */
 20 #define DEVFREQ_GOV_SIMPLE_ONDEMAND     "simple_ondemand"
 21 #define DEVFREQ_GOV_PERFORMANCE         "performance"
 22 #define DEVFREQ_GOV_POWERSAVE           "powersave"
 23 #define DEVFREQ_GOV_USERSPACE           "userspace"
 24 #define DEVFREQ_GOV_PASSIVE             "passive"
 25 
 26 /* DEVFREQ notifier interface */
 27 #define DEVFREQ_TRANSITION_NOTIFIER     (0)
 28 
 29 /* Transition notifiers of DEVFREQ_TRANSITION_NOTIFIER */
 30 #define DEVFREQ_PRECHANGE               (0)
 31 #define DEVFREQ_POSTCHANGE              (1)
 32 
 33 struct devfreq;
 34 struct devfreq_governor;
 35 
 36 /**
 37  * struct devfreq_dev_status - Data given from devfreq user device to
 38  *                           governors. Represents the performance
 39  *                           statistics.
 40  * @total_time:         The total time represented by this instance of
 41  *                      devfreq_dev_status
 42  * @busy_time:          The time that the device was working among the
 43  *                      total_time.
 44  * @current_frequency:  The operating frequency.
 45  * @private_data:       An entry not specified by the devfreq framework.
 46  *                      A device and a specific governor may have their
 47  *                      own protocol with private_data. However, because
 48  *                      this is governor-specific, a governor using this
 49  *                      will be only compatible with devices aware of it.
 50  */
 51 struct devfreq_dev_status {
 52         /* both since the last measure */
 53         unsigned long total_time;
 54         unsigned long busy_time;
 55         unsigned long current_frequency;
 56         void *private_data;
 57 };
 58 
 59 /*
 60  * The resulting frequency should be at most this. (this bound is the
 61  * least upper bound; thus, the resulting freq should be lower or same)
 62  * If the flag is not set, the resulting frequency should be at most the
 63  * bound (greatest lower bound)
 64  */
 65 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND          0x1
 66 
 67 /**
 68  * struct devfreq_dev_profile - Devfreq's user device profile
 69  * @initial_freq:       The operating frequency when devfreq_add_device() is
 70  *                      called.
 71  * @polling_ms:         The polling interval in ms. 0 disables polling.
 72  * @target:             The device should set its operating frequency at
 73  *                      freq or lowest-upper-than-freq value. If freq is
 74  *                      higher than any operable frequency, set maximum.
 75  *                      Before returning, target function should set
 76  *                      freq at the current frequency.
 77  *                      The "flags" parameter's possible values are
 78  *                      explained above with "DEVFREQ_FLAG_*" macros.
 79  * @get_dev_status:     The device should provide the current performance
 80  *                      status to devfreq. Governors are recommended not to
 81  *                      use this directly. Instead, governors are recommended
 82  *                      to use devfreq_update_stats() along with
 83  *                      devfreq.last_status.
 84  * @get_cur_freq:       The device should provide the current frequency
 85  *                      at which it is operating.
 86  * @exit:               An optional callback that is called when devfreq
 87  *                      is removing the devfreq object due to error or
 88  *                      from devfreq_remove_device() call. If the user
 89  *                      has registered devfreq->nb at a notifier-head,
 90  *                      this is the time to unregister it.
 91  * @freq_table:         Optional list of frequencies to support statistics
 92  *                      and freq_table must be generated in ascending order.
 93  * @max_state:          The size of freq_table.
 94  */
 95 struct devfreq_dev_profile {
 96         unsigned long initial_freq;
 97         unsigned int polling_ms;
 98 
 99         int (*target)(struct device *dev, unsigned long *freq, u32 flags);
100         int (*get_dev_status)(struct device *dev,
101                               struct devfreq_dev_status *stat);
102         int (*get_cur_freq)(struct device *dev, unsigned long *freq);
103         void (*exit)(struct device *dev);
104 
105         unsigned long *freq_table;
106         unsigned int max_state;
107 };
108 
109 /**
110  * struct devfreq - Device devfreq structure
111  * @node:       list node - contains the devices with devfreq that have been
112  *              registered.
113  * @lock:       a mutex to protect accessing devfreq.
114  * @dev:        device registered by devfreq class. dev.parent is the device
115  *              using devfreq.
116  * @profile:    device-specific devfreq profile
117  * @governor:   method how to choose frequency based on the usage.
118  * @governor_name:      devfreq governor name for use with this devfreq
119  * @nb:         notifier block used to notify devfreq object that it should
120  *              reevaluate operable frequencies. Devfreq users may use
121  *              devfreq.nb to the corresponding register notifier call chain.
122  * @work:       delayed work for load monitoring.
123  * @previous_freq:      previously configured frequency value.
124  * @data:       Private data of the governor. The devfreq framework does not
125  *              touch this.
126  * @min_freq:   Limit minimum frequency requested by user (0: none)
127  * @max_freq:   Limit maximum frequency requested by user (0: none)
128  * @scaling_min_freq:   Limit minimum frequency requested by OPP interface
129  * @scaling_max_freq:   Limit maximum frequency requested by OPP interface
130  * @stop_polling:        devfreq polling status of a device.
131  * @suspend_freq:        frequency of a device set during suspend phase.
132  * @resume_freq:         frequency of a device set in resume phase.
133  * @suspend_count:       suspend requests counter for a device.
134  * @total_trans:        Number of devfreq transitions
135  * @trans_table:        Statistics of devfreq transitions
136  * @time_in_state:      Statistics of devfreq states
137  * @last_stat_updated:  The last time stat updated
138  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
139  *
140  * This structure stores the devfreq information for a give device.
141  *
142  * Note that when a governor accesses entries in struct devfreq in its
143  * functions except for the context of callbacks defined in struct
144  * devfreq_governor, the governor should protect its access with the
145  * struct mutex lock in struct devfreq. A governor may use this mutex
146  * to protect its own private data in void *data as well.
147  */
148 struct devfreq {
149         struct list_head node;
150 
151         struct mutex lock;
152         struct device dev;
153         struct devfreq_dev_profile *profile;
154         const struct devfreq_governor *governor;
155         char governor_name[DEVFREQ_NAME_LEN];
156         struct notifier_block nb;
157         struct delayed_work work;
158 
159         unsigned long previous_freq;
160         struct devfreq_dev_status last_status;
161 
162         void *data; /* private data for governors */
163 
164         unsigned long min_freq;
165         unsigned long max_freq;
166         unsigned long scaling_min_freq;
167         unsigned long scaling_max_freq;
168         bool stop_polling;
169 
170         unsigned long suspend_freq;
171         unsigned long resume_freq;
172         atomic_t suspend_count;
173 
174         /* information for device frequency transition */
175         unsigned int total_trans;
176         unsigned int *trans_table;
177         unsigned long *time_in_state;
178         unsigned long last_stat_updated;
179 
180         struct srcu_notifier_head transition_notifier_list;
181 };
182 
183 struct devfreq_freqs {
184         unsigned long old;
185         unsigned long new;
186 };
187 
188 #if defined(CONFIG_PM_DEVFREQ)
189 extern struct devfreq *devfreq_add_device(struct device *dev,
190                                   struct devfreq_dev_profile *profile,
191                                   const char *governor_name,
192                                   void *data);
193 extern int devfreq_remove_device(struct devfreq *devfreq);
194 extern struct devfreq *devm_devfreq_add_device(struct device *dev,
195                                   struct devfreq_dev_profile *profile,
196                                   const char *governor_name,
197                                   void *data);
198 extern void devm_devfreq_remove_device(struct device *dev,
199                                   struct devfreq *devfreq);
200 
201 /* Supposed to be called by PM callbacks */
202 extern int devfreq_suspend_device(struct devfreq *devfreq);
203 extern int devfreq_resume_device(struct devfreq *devfreq);
204 
205 extern void devfreq_suspend(void);
206 extern void devfreq_resume(void);
207 
208 /**
209  * update_devfreq() - Reevaluate the device and configure frequency
210  * @devfreq:    the devfreq device
211  *
212  * Note: devfreq->lock must be held
213  */
214 extern int update_devfreq(struct devfreq *devfreq);
215 
216 /* Helper functions for devfreq user device driver with OPP. */
217 extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
218                                            unsigned long *freq, u32 flags);
219 extern int devfreq_register_opp_notifier(struct device *dev,
220                                          struct devfreq *devfreq);
221 extern int devfreq_unregister_opp_notifier(struct device *dev,
222                                            struct devfreq *devfreq);
223 extern int devm_devfreq_register_opp_notifier(struct device *dev,
224                                               struct devfreq *devfreq);
225 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
226                                                 struct devfreq *devfreq);
227 extern int devfreq_register_notifier(struct devfreq *devfreq,
228                                         struct notifier_block *nb,
229                                         unsigned int list);
230 extern int devfreq_unregister_notifier(struct devfreq *devfreq,
231                                         struct notifier_block *nb,
232                                         unsigned int list);
233 extern int devm_devfreq_register_notifier(struct device *dev,
234                                 struct devfreq *devfreq,
235                                 struct notifier_block *nb,
236                                 unsigned int list);
237 extern void devm_devfreq_unregister_notifier(struct device *dev,
238                                 struct devfreq *devfreq,
239                                 struct notifier_block *nb,
240                                 unsigned int list);
241 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
242                                                 int index);
243 
244 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
245 /**
246  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
247  *      and devfreq_add_device
248  * @upthreshold:        If the load is over this value, the frequency jumps.
249  *                      Specify 0 to use the default. Valid value = 0 to 100.
250  * @downdifferential:   If the load is under upthreshold - downdifferential,
251  *                      the governor may consider slowing the frequency down.
252  *                      Specify 0 to use the default. Valid value = 0 to 100.
253  *                      downdifferential < upthreshold must hold.
254  *
255  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
256  * the governor uses the default values.
257  */
258 struct devfreq_simple_ondemand_data {
259         unsigned int upthreshold;
260         unsigned int downdifferential;
261 };
262 #endif
263 
264 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
265 /**
266  * struct devfreq_passive_data - void *data fed to struct devfreq
267  *      and devfreq_add_device
268  * @parent:     the devfreq instance of parent device.
269  * @get_target_freq:    Optional callback, Returns desired operating frequency
270  *                      for the device using passive governor. That is called
271  *                      when passive governor should decide the next frequency
272  *                      by using the new frequency of parent devfreq device
273  *                      using governors except for passive governor.
274  *                      If the devfreq device has the specific method to decide
275  *                      the next frequency, should use this callback.
276  * @this:       the devfreq instance of own device.
277  * @nb:         the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
278  *
279  * The devfreq_passive_data have to set the devfreq instance of parent
280  * device with governors except for the passive governor. But, don't need to
281  * initialize the 'this' and 'nb' field because the devfreq core will handle
282  * them.
283  */
284 struct devfreq_passive_data {
285         /* Should set the devfreq instance of parent device */
286         struct devfreq *parent;
287 
288         /* Optional callback to decide the next frequency of passvice device */
289         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
290 
291         /* For passive governor's internal use. Don't need to set them */
292         struct devfreq *this;
293         struct notifier_block nb;
294 };
295 #endif
296 
297 #else /* !CONFIG_PM_DEVFREQ */
298 static inline struct devfreq *devfreq_add_device(struct device *dev,
299                                           struct devfreq_dev_profile *profile,
300                                           const char *governor_name,
301                                           void *data)
302 {
303         return ERR_PTR(-ENOSYS);
304 }
305 
306 static inline int devfreq_remove_device(struct devfreq *devfreq)
307 {
308         return 0;
309 }
310 
311 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
312                                         struct devfreq_dev_profile *profile,
313                                         const char *governor_name,
314                                         void *data)
315 {
316         return ERR_PTR(-ENOSYS);
317 }
318 
319 static inline void devm_devfreq_remove_device(struct device *dev,
320                                         struct devfreq *devfreq)
321 {
322 }
323 
324 static inline int devfreq_suspend_device(struct devfreq *devfreq)
325 {
326         return 0;
327 }
328 
329 static inline int devfreq_resume_device(struct devfreq *devfreq)
330 {
331         return 0;
332 }
333 
334 static inline void devfreq_suspend(void) {}
335 static inline void devfreq_resume(void) {}
336 
337 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
338                                            unsigned long *freq, u32 flags)
339 {
340         return ERR_PTR(-EINVAL);
341 }
342 
343 static inline int devfreq_register_opp_notifier(struct device *dev,
344                                          struct devfreq *devfreq)
345 {
346         return -EINVAL;
347 }
348 
349 static inline int devfreq_unregister_opp_notifier(struct device *dev,
350                                            struct devfreq *devfreq)
351 {
352         return -EINVAL;
353 }
354 
355 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
356                                                      struct devfreq *devfreq)
357 {
358         return -EINVAL;
359 }
360 
361 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
362                                                         struct devfreq *devfreq)
363 {
364 }
365 
366 static inline int devfreq_register_notifier(struct devfreq *devfreq,
367                                         struct notifier_block *nb,
368                                         unsigned int list)
369 {
370         return 0;
371 }
372 
373 static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
374                                         struct notifier_block *nb,
375                                         unsigned int list)
376 {
377         return 0;
378 }
379 
380 static inline int devm_devfreq_register_notifier(struct device *dev,
381                                 struct devfreq *devfreq,
382                                 struct notifier_block *nb,
383                                 unsigned int list)
384 {
385         return 0;
386 }
387 
388 static inline void devm_devfreq_unregister_notifier(struct device *dev,
389                                 struct devfreq *devfreq,
390                                 struct notifier_block *nb,
391                                 unsigned int list)
392 {
393 }
394 
395 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
396                                                         int index)
397 {
398         return ERR_PTR(-ENODEV);
399 }
400 
401 static inline int devfreq_update_stats(struct devfreq *df)
402 {
403         return -EINVAL;
404 }
405 #endif /* CONFIG_PM_DEVFREQ */
406 
407 #endif /* __LINUX_DEVFREQ_H__ */
408 

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