include/linux/devfreq.h

   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 /* DEVFREQ notifier interface */
  23 #define DEVFREQ_TRANSITION_NOTIFIER     (0)
  24
  25 /* Transition notifiers of DEVFREQ_TRANSITION_NOTIFIER */
  26 #define DEVFREQ_PRECHANGE               (0)
  27 #define DEVFREQ_POSTCHANGE              (1)
  28
  29 struct devfreq;
  30
  31 /**
  32  * struct devfreq_dev_status - Data given from devfreq user device to
  33  *                           governors. Represents the performance
  34  *                           statistics.
  35  * @total_time:         The total time represented by this instance of
  36  *                      devfreq_dev_status
  37  * @busy_time:          The time that the device was working among the
  38  *                      total_time.
  39  * @current_frequency:  The operating frequency.
  40  * @private_data:       An entry not specified by the devfreq framework.
  41  *                      A device and a specific governor may have their
  42  *                      own protocol with private_data. However, because
  43  *                      this is governor-specific, a governor using this
  44  *                      will be only compatible with devices aware of it.
  45  */
  46 struct devfreq_dev_status {
  47         /* both since the last measure */
  48         unsigned long total_time;
  49         unsigned long busy_time;
  50         unsigned long current_frequency;
  51         void *private_data;
  52 };
  53
  54 /*
  55  * The resulting frequency should be at most this. (this bound is the
  56  * least upper bound; thus, the resulting freq should be lower or same)
  57  * If the flag is not set, the resulting frequency should be at most the
  58  * bound (greatest lower bound)
  59  */
  60 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND          0x1
  61
  62 /**
  63  * struct devfreq_dev_profile - Devfreq's user device profile
  64  * @initial_freq:       The operating frequency when devfreq_add_device() is
  65  *                      called.
  66  * @polling_ms:         The polling interval in ms. 0 disables polling.
  67  * @target:             The device should set its operating frequency at
  68  *                      freq or lowest-upper-than-freq value. If freq is
  69  *                      higher than any operable frequency, set maximum.
  70  *                      Before returning, target function should set
  71  *                      freq at the current frequency.
  72  *                      The "flags" parameter's possible values are
  73  *                      explained above with "DEVFREQ_FLAG_*" macros.
  74  * @get_dev_status:     The device should provide the current performance
  75  *                      status to devfreq. Governors are recommended not to
  76  *                      use this directly. Instead, governors are recommended
  77  *                      to use devfreq_update_stats() along with
  78  *                      devfreq.last_status.
  79  * @get_cur_freq:       The device should provide the current frequency
  80  *                      at which it is operating.
  81  * @exit:               An optional callback that is called when devfreq
  82  *                      is removing the devfreq object due to error or
  83  *                      from devfreq_remove_device() call. If the user
  84  *                      has registered devfreq->nb at a notifier-head,
  85  *                      this is the time to unregister it.
  86  * @freq_table: Optional list of frequencies to support statistics.
  87  * @max_state:  The size of freq_table.
  88  */
  89 struct devfreq_dev_profile {
  90         unsigned long initial_freq;
  91         unsigned int polling_ms;
  92
  93         int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  94         int (*get_dev_status)(struct device *dev,
  95                               struct devfreq_dev_status *stat);
  96         int (*get_cur_freq)(struct device *dev, unsigned long *freq);
  97         void (*exit)(struct device *dev);
  98
  99         unsigned long *freq_table;
 100         unsigned int max_state;
 101 };
 102
 103 /**
 104  * struct devfreq_governor - Devfreq policy governor
 105  * @node:               list node - contains registered devfreq governors
 106  * @name:               Governor's name
 107  * @get_target_freq:    Returns desired operating frequency for the device.
 108  *                      Basically, get_target_freq will run
 109  *                      devfreq_dev_profile.get_dev_status() to get the
 110  *                      status of the device (load = busy_time / total_time).
 111  *                      If no_central_polling is set, this callback is called
 112  *                      only with update_devfreq() notified by OPP.
 113  * @event_handler:      Callback for devfreq core framework to notify events
 114  *                      to governors. Events include per device governor
 115  *                      init and exit, opp changes out of devfreq, suspend
 116  *                      and resume of per device devfreq during device idle.
 117  *
 118  * Note that the callbacks are called with devfreq->lock locked by devfreq.
 119  */
 120 struct devfreq_governor {
 121         struct list_head node;
 122
 123         const char name[DEVFREQ_NAME_LEN];
 124         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 125         int (*event_handler)(struct devfreq *devfreq,
 126                                 unsigned int event, void *data);
 127 };
 128
 129 /**
 130  * struct devfreq - Device devfreq structure
 131  * @node:       list node - contains the devices with devfreq that have been
 132  *              registered.
 133  * @lock:       a mutex to protect accessing devfreq.
 134  * @dev:        device registered by devfreq class. dev.parent is the device
 135  *              using devfreq.
 136  * @profile:    device-specific devfreq profile
 137  * @governor:   method how to choose frequency based on the usage.
 138  * @governor_name:      devfreq governor name for use with this devfreq
 139  * @nb:         notifier block used to notify devfreq object that it should
 140  *              reevaluate operable frequencies. Devfreq users may use
 141  *              devfreq.nb to the corresponding register notifier call chain.
 142  * @work:       delayed work for load monitoring.
 143  * @previous_freq:      previously configured frequency value.
 144  * @data:       Private data of the governor. The devfreq framework does not
 145  *              touch this.
 146  * @min_freq:   Limit minimum frequency requested by user (0: none)
 147  * @max_freq:   Limit maximum frequency requested by user (0: none)
 148  * @stop_polling:        devfreq polling status of a device.
 149  * @total_trans:        Number of devfreq transitions
 150  * @trans_table:        Statistics of devfreq transitions
 151  * @time_in_state:      Statistics of devfreq states
 152  * @last_stat_updated:  The last time stat updated
 153  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
 154  *
 155  * This structure stores the devfreq information for a give device.
 156  *
 157  * Note that when a governor accesses entries in struct devfreq in its
 158  * functions except for the context of callbacks defined in struct
 159  * devfreq_governor, the governor should protect its access with the
 160  * struct mutex lock in struct devfreq. A governor may use this mutex
 161  * to protect its own private data in void *data as well.
 162  */
 163 struct devfreq {
 164         struct list_head node;
 165
 166         struct mutex lock;
 167         struct device dev;
 168         struct devfreq_dev_profile *profile;
 169         const struct devfreq_governor *governor;
 170         char governor_name[DEVFREQ_NAME_LEN];
 171         struct notifier_block nb;
 172         struct delayed_work work;
 173
 174         unsigned long previous_freq;
 175         struct devfreq_dev_status last_status;
 176
 177         void *data; /* private data for governors */
 178
 179         unsigned long min_freq;
 180         unsigned long max_freq;
 181         bool stop_polling;
 182
 183         /* information for device frequency transition */
 184         unsigned int total_trans;
 185         unsigned int *trans_table;
 186         unsigned long *time_in_state;
 187         unsigned long last_stat_updated;
 188
 189         struct srcu_notifier_head transition_notifier_list;
 190 };
 191
 192 struct devfreq_freqs {
 193         unsigned long old;
 194         unsigned long new;
 195 };
 196
 197 #if defined(CONFIG_PM_DEVFREQ)
 198 extern struct devfreq *devfreq_add_device(struct device *dev,
 199                                   struct devfreq_dev_profile *profile,
 200                                   const char *governor_name,
 201                                   void *data);
 202 extern int devfreq_remove_device(struct devfreq *devfreq);
 203 extern struct devfreq *devm_devfreq_add_device(struct device *dev,
 204                                   struct devfreq_dev_profile *profile,
 205                                   const char *governor_name,
 206                                   void *data);
 207 extern void devm_devfreq_remove_device(struct device *dev,
 208                                   struct devfreq *devfreq);
 209
 210 /* Supposed to be called by PM callbacks */
 211 extern int devfreq_suspend_device(struct devfreq *devfreq);
 212 extern int devfreq_resume_device(struct devfreq *devfreq);
 213
 214 /* Helper functions for devfreq user device driver with OPP. */
 215 extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 216                                            unsigned long *freq, u32 flags);
 217 extern int devfreq_register_opp_notifier(struct device *dev,
 218                                          struct devfreq *devfreq);
 219 extern int devfreq_unregister_opp_notifier(struct device *dev,
 220                                            struct devfreq *devfreq);
 221 extern int devm_devfreq_register_opp_notifier(struct device *dev,
 222                                               struct devfreq *devfreq);
 223 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
 224                                                 struct devfreq *devfreq);
 225 extern int devfreq_register_notifier(struct devfreq *devfreq,
 226                                         struct notifier_block *nb,
 227                                         unsigned int list);
 228 extern int devfreq_unregister_notifier(struct devfreq *devfreq,
 229                                         struct notifier_block *nb,
 230                                         unsigned int list);
 231 extern int devm_devfreq_register_notifier(struct device *dev,
 232                                 struct devfreq *devfreq,
 233                                 struct notifier_block *nb,
 234                                 unsigned int list);
 235 extern void devm_devfreq_unregister_notifier(struct device *dev,
 236                                 struct devfreq *devfreq,
 237                                 struct notifier_block *nb,
 238                                 unsigned int list);
 239 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 240                                                 int index);
 241
 242 /**
 243  * devfreq_update_stats() - update the last_status pointer in struct devfreq
 244  * @df:         the devfreq instance whose status needs updating
 245  *
 246  *  Governors are recommended to use this function along with last_status,
 247  * which allows other entities to reuse the last_status without affecting
 248  * the values fetched later by governors.
 249  */
 250 static inline int devfreq_update_stats(struct devfreq *df)
 251 {
 252         return df->profile->get_dev_status(df->dev.parent, &df->last_status);
 253 }
 254
 255 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 256 /**
 257  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 258  *      and devfreq_add_device
 259  * @upthreshold:        If the load is over this value, the frequency jumps.
 260  *                      Specify 0 to use the default. Valid value = 0 to 100.
 261  * @downdifferential:   If the load is under upthreshold - downdifferential,
 262  *                      the governor may consider slowing the frequency down.
 263  *                      Specify 0 to use the default. Valid value = 0 to 100.
 264  *                      downdifferential < upthreshold must hold.
 265  *
 266  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 267  * the governor uses the default values.
 268  */
 269 struct devfreq_simple_ondemand_data {
 270         unsigned int upthreshold;
 271         unsigned int downdifferential;
 272 };
 273 #endif
 274
 275 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
 276 /**
 277  * struct devfreq_passive_data - void *data fed to struct devfreq
 278  *      and devfreq_add_device
 279  * @parent:     the devfreq instance of parent device.
 280  * @get_target_freq:    Optional callback, Returns desired operating frequency
 281  *                      for the device using passive governor. That is called
 282  *                      when passive governor should decide the next frequency
 283  *                      by using the new frequency of parent devfreq device
 284  *                      using governors except for passive governor.
 285  *                      If the devfreq device has the specific method to decide
 286  *                      the next frequency, should use this callback.
 287  * @this:       the devfreq instance of own device.
 288  * @nb:         the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
 289  *
 290  * The devfreq_passive_data have to set the devfreq instance of parent
 291  * device with governors except for the passive governor. But, don't need to
 292  * initialize the 'this' and 'nb' field because the devfreq core will handle
 293  * them.
 294  */
 295 struct devfreq_passive_data {
 296         /* Should set the devfreq instance of parent device */
 297         struct devfreq *parent;
 298
 299         /* Optional callback to decide the next frequency of passvice device */
 300         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 301
 302         /* For passive governor's internal use. Don't need to set them */
 303         struct devfreq *this;
 304         struct notifier_block nb;
 305 };
 306 #endif
 307
 308 #else /* !CONFIG_PM_DEVFREQ */
 309 static inline struct devfreq *devfreq_add_device(struct device *dev,
 310                                           struct devfreq_dev_profile *profile,
 311                                           const char *governor_name,
 312                                           void *data)
 313 {
 314         return ERR_PTR(-ENOSYS);
 315 }
 316
 317 static inline int devfreq_remove_device(struct devfreq *devfreq)
 318 {
 319         return 0;
 320 }
 321
 322 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
 323                                         struct devfreq_dev_profile *profile,
 324                                         const char *governor_name,
 325                                         void *data)
 326 {
 327         return ERR_PTR(-ENOSYS);
 328 }
 329
 330 static inline void devm_devfreq_remove_device(struct device *dev,
 331                                         struct devfreq *devfreq)
 332 {
 333 }
 334
 335 static inline int devfreq_suspend_device(struct devfreq *devfreq)
 336 {
 337         return 0;
 338 }
 339
 340 static inline int devfreq_resume_device(struct devfreq *devfreq)
 341 {
 342         return 0;
 343 }
 344
 345 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 346                                            unsigned long *freq, u32 flags)
 347 {
 348         return ERR_PTR(-EINVAL);
 349 }
 350
 351 static inline int devfreq_register_opp_notifier(struct device *dev,
 352                                          struct devfreq *devfreq)
 353 {
 354         return -EINVAL;
 355 }
 356
 357 static inline int devfreq_unregister_opp_notifier(struct device *dev,
 358                                            struct devfreq *devfreq)
 359 {
 360         return -EINVAL;
 361 }
 362
 363 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
 364                                                      struct devfreq *devfreq)
 365 {
 366         return -EINVAL;
 367 }
 368
 369 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
 370                                                         struct devfreq *devfreq)
 371 {
 372 }
 373
 374 static inline int devfreq_register_notifier(struct devfreq *devfreq,
 375                                         struct notifier_block *nb,
 376                                         unsigned int list)
 377 {
 378         return 0;
 379 }
 380
 381 static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
 382                                         struct notifier_block *nb,
 383                                         unsigned int list)
 384 {
 385         return 0;
 386 }
 387
 388 static inline int devm_devfreq_register_notifier(struct device *dev,
 389                                 struct devfreq *devfreq,
 390                                 struct notifier_block *nb,
 391                                 unsigned int list)
 392 {
 393         return 0;
 394 }
 395
 396 static inline void devm_devfreq_unregister_notifier(struct device *dev,
 397                                 struct devfreq *devfreq,
 398                                 struct notifier_block *nb,
 399                                 unsigned int list)
 400 {
 401 }
 402
 403 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 404                                                         int index)
 405 {
 406         return ERR_PTR(-ENODEV);
 407 }
 408
 409 static inline int devfreq_update_stats(struct devfreq *df)
 410 {
 411         return -EINVAL;
 412 }
 413 #endif /* CONFIG_PM_DEVFREQ */
 414
 415 #endif /* __LINUX_DEVFREQ_H__ */