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 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__ */