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  * @immutable:          Immutable flag for governor. If the value is 1,
 108  *                      this govenror is never changeable to other governor.
 109  * @get_target_freq:    Returns desired operating frequency for the device.
 110  *                      Basically, get_target_freq will run
 111  *                      devfreq_dev_profile.get_dev_status() to get the
 112  *                      status of the device (load = busy_time / total_time).
 113  *                      If no_central_polling is set, this callback is called
 114  *                      only with update_devfreq() notified by OPP.
 115  * @event_handler:      Callback for devfreq core framework to notify events
 116  *                      to governors. Events include per device governor
 117  *                      init and exit, opp changes out of devfreq, suspend
 118  *                      and resume of per device devfreq during device idle.
 119  *
 120  * Note that the callbacks are called with devfreq->lock locked by devfreq.
 121  */
 122 struct devfreq_governor {
 123         struct list_head node;
 124
 125         const char name[DEVFREQ_NAME_LEN];
 126         const unsigned int immutable;
 127         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 128         int (*event_handler)(struct devfreq *devfreq,
 129                                 unsigned int event, void *data);
 130 };
 131
 132 /**
 133  * struct devfreq - Device devfreq structure
 134  * @node:       list node - contains the devices with devfreq that have been
 135  *              registered.
 136  * @lock:       a mutex to protect accessing devfreq.
 137  * @dev:        device registered by devfreq class. dev.parent is the device
 138  *              using devfreq.
 139  * @profile:    device-specific devfreq profile
 140  * @governor:   method how to choose frequency based on the usage.
 141  * @governor_name:      devfreq governor name for use with this devfreq
 142  * @nb:         notifier block used to notify devfreq object that it should
 143  *              reevaluate operable frequencies. Devfreq users may use
 144  *              devfreq.nb to the corresponding register notifier call chain.
 145  * @work:       delayed work for load monitoring.
 146  * @previous_freq:      previously configured frequency value.
 147  * @data:       Private data of the governor. The devfreq framework does not
 148  *              touch this.
 149  * @min_freq:   Limit minimum frequency requested by user (0: none)
 150  * @max_freq:   Limit maximum frequency requested by user (0: none)
 151  * @stop_polling:        devfreq polling status of a device.
 152  * @total_trans:        Number of devfreq transitions
 153  * @trans_table:        Statistics of devfreq transitions
 154  * @time_in_state:      Statistics of devfreq states
 155  * @last_stat_updated:  The last time stat updated
 156  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
 157  *
 158  * This structure stores the devfreq information for a give device.
 159  *
 160  * Note that when a governor accesses entries in struct devfreq in its
 161  * functions except for the context of callbacks defined in struct
 162  * devfreq_governor, the governor should protect its access with the
 163  * struct mutex lock in struct devfreq. A governor may use this mutex
 164  * to protect its own private data in void *data as well.
 165  */
 166 struct devfreq {
 167         struct list_head node;
 168
 169         struct mutex lock;
 170         struct device dev;
 171         struct devfreq_dev_profile *profile;
 172         const struct devfreq_governor *governor;
 173         char governor_name[DEVFREQ_NAME_LEN];
 174         struct notifier_block nb;
 175         struct delayed_work work;
 176
 177         unsigned long previous_freq;
 178         struct devfreq_dev_status last_status;
 179
 180         void *data; /* private data for governors */
 181
 182         unsigned long min_freq;
 183         unsigned long max_freq;
 184         bool stop_polling;
 185
 186         /* information for device frequency transition */
 187         unsigned int total_trans;
 188         unsigned int *trans_table;
 189         unsigned long *time_in_state;
 190         unsigned long last_stat_updated;
 191
 192         struct srcu_notifier_head transition_notifier_list;
 193 };
 194
 195 struct devfreq_freqs {
 196         unsigned long old;
 197         unsigned long new;
 198 };
 199
 200 #if defined(CONFIG_PM_DEVFREQ)
 201 extern struct devfreq *devfreq_add_device(struct device *dev,
 202                                   struct devfreq_dev_profile *profile,
 203                                   const char *governor_name,
 204                                   void *data);
 205 extern int devfreq_remove_device(struct devfreq *devfreq);
 206 extern struct devfreq *devm_devfreq_add_device(struct device *dev,
 207                                   struct devfreq_dev_profile *profile,
 208                                   const char *governor_name,
 209                                   void *data);
 210 extern void devm_devfreq_remove_device(struct device *dev,
 211                                   struct devfreq *devfreq);
 212
 213 /* Supposed to be called by PM callbacks */
 214 extern int devfreq_suspend_device(struct devfreq *devfreq);
 215 extern int devfreq_resume_device(struct devfreq *devfreq);
 216
 217 /* Helper functions for devfreq user device driver with OPP. */
 218 extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 219                                            unsigned long *freq, u32 flags);
 220 extern int devfreq_register_opp_notifier(struct device *dev,
 221                                          struct devfreq *devfreq);
 222 extern int devfreq_unregister_opp_notifier(struct device *dev,
 223                                            struct devfreq *devfreq);
 224 extern int devm_devfreq_register_opp_notifier(struct device *dev,
 225                                               struct devfreq *devfreq);
 226 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
 227                                                 struct devfreq *devfreq);
 228 extern int devfreq_register_notifier(struct devfreq *devfreq,
 229                                         struct notifier_block *nb,
 230                                         unsigned int list);
 231 extern int devfreq_unregister_notifier(struct devfreq *devfreq,
 232                                         struct notifier_block *nb,
 233                                         unsigned int list);
 234 extern int devm_devfreq_register_notifier(struct device *dev,
 235                                 struct devfreq *devfreq,
 236                                 struct notifier_block *nb,
 237                                 unsigned int list);
 238 extern void devm_devfreq_unregister_notifier(struct device *dev,
 239                                 struct devfreq *devfreq,
 240                                 struct notifier_block *nb,
 241                                 unsigned int list);
 242 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 243                                                 int index);
 244
 245 /**
 246  * devfreq_update_stats() - update the last_status pointer in struct devfreq
 247  * @df:         the devfreq instance whose status needs updating
 248  *
 249  *  Governors are recommended to use this function along with last_status,
 250  * which allows other entities to reuse the last_status without affecting
 251  * the values fetched later by governors.
 252  */
 253 static inline int devfreq_update_stats(struct devfreq *df)
 254 {
 255         return df->profile->get_dev_status(df->dev.parent, &df->last_status);
 256 }
 257
 258 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 259 /**
 260  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 261  *      and devfreq_add_device
 262  * @upthreshold:        If the load is over this value, the frequency jumps.
 263  *                      Specify 0 to use the default. Valid value = 0 to 100.
 264  * @downdifferential:   If the load is under upthreshold - downdifferential,
 265  *                      the governor may consider slowing the frequency down.
 266  *                      Specify 0 to use the default. Valid value = 0 to 100.
 267  *                      downdifferential < upthreshold must hold.
 268  *
 269  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 270  * the governor uses the default values.
 271  */
 272 struct devfreq_simple_ondemand_data {
 273         unsigned int upthreshold;
 274         unsigned int downdifferential;
 275 };
 276 #endif
 277
 278 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
 279 /**
 280  * struct devfreq_passive_data - void *data fed to struct devfreq
 281  *      and devfreq_add_device
 282  * @parent:     the devfreq instance of parent device.
 283  * @get_target_freq:    Optional callback, Returns desired operating frequency
 284  *                      for the device using passive governor. That is called
 285  *                      when passive governor should decide the next frequency
 286  *                      by using the new frequency of parent devfreq device
 287  *                      using governors except for passive governor.
 288  *                      If the devfreq device has the specific method to decide
 289  *                      the next frequency, should use this callback.
 290  * @this:       the devfreq instance of own device.
 291  * @nb:         the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
 292  *
 293  * The devfreq_passive_data have to set the devfreq instance of parent
 294  * device with governors except for the passive governor. But, don't need to
 295  * initialize the 'this' and 'nb' field because the devfreq core will handle
 296  * them.
 297  */
 298 struct devfreq_passive_data {
 299         /* Should set the devfreq instance of parent device */
 300         struct devfreq *parent;
 301
 302         /* Optional callback to decide the next frequency of passvice device */
 303         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 304
 305         /* For passive governor's internal use. Don't need to set them */
 306         struct devfreq *this;
 307         struct notifier_block nb;
 308 };
 309 #endif
 310
 311 #else /* !CONFIG_PM_DEVFREQ */
 312 static inline struct devfreq *devfreq_add_device(struct device *dev,
 313                                           struct devfreq_dev_profile *profile,
 314                                           const char *governor_name,
 315                                           void *data)
 316 {
 317         return ERR_PTR(-ENOSYS);
 318 }
 319
 320 static inline int devfreq_remove_device(struct devfreq *devfreq)
 321 {
 322         return 0;
 323 }
 324
 325 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
 326                                         struct devfreq_dev_profile *profile,
 327                                         const char *governor_name,
 328                                         void *data)
 329 {
 330         return ERR_PTR(-ENOSYS);
 331 }
 332
 333 static inline void devm_devfreq_remove_device(struct device *dev,
 334                                         struct devfreq *devfreq)
 335 {
 336 }
 337
 338 static inline int devfreq_suspend_device(struct devfreq *devfreq)
 339 {
 340         return 0;
 341 }
 342
 343 static inline int devfreq_resume_device(struct devfreq *devfreq)
 344 {
 345         return 0;
 346 }
 347
 348 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 349                                            unsigned long *freq, u32 flags)
 350 {
 351         return ERR_PTR(-EINVAL);
 352 }
 353
 354 static inline int devfreq_register_opp_notifier(struct device *dev,
 355                                          struct devfreq *devfreq)
 356 {
 357         return -EINVAL;
 358 }
 359
 360 static inline int devfreq_unregister_opp_notifier(struct device *dev,
 361                                            struct devfreq *devfreq)
 362 {
 363         return -EINVAL;
 364 }
 365
 366 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
 367                                                      struct devfreq *devfreq)
 368 {
 369         return -EINVAL;
 370 }
 371
 372 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
 373                                                         struct devfreq *devfreq)
 374 {
 375 }
 376
 377 static inline int devfreq_register_notifier(struct devfreq *devfreq,
 378                                         struct notifier_block *nb,
 379                                         unsigned int list)
 380 {
 381         return 0;
 382 }
 383
 384 static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
 385                                         struct notifier_block *nb,
 386                                         unsigned int list)
 387 {
 388         return 0;
 389 }
 390
 391 static inline int devm_devfreq_register_notifier(struct device *dev,
 392                                 struct devfreq *devfreq,
 393                                 struct notifier_block *nb,
 394                                 unsigned int list)
 395 {
 396         return 0;
 397 }
 398
 399 static inline void devm_devfreq_unregister_notifier(struct device *dev,
 400                                 struct devfreq *devfreq,
 401                                 struct notifier_block *nb,
 402                                 unsigned int list)
 403 {
 404 }
 405
 406 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 407                                                         int index)
 408 {
 409         return ERR_PTR(-ENODEV);
 410 }
 411
 412 static inline int devfreq_update_stats(struct devfreq *df)
 413 {
 414         return -EINVAL;
 415 }
 416 #endif /* CONFIG_PM_DEVFREQ */
 417
 418 #endif /* __LINUX_DEVFREQ_H__ */