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