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/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, which is used by governors.
  69  * @get_cur_freq:       The device should provide the current frequency
  70  *                      at which it is operating.
  71  * @exit:               An optional callback that is called when devfreq
  72  *                      is removing the devfreq object due to error or
  73  *                      from devfreq_remove_device() call. If the user
  74  *                      has registered devfreq->nb at a notifier-head,
  75  *                      this is the time to unregister it.
  76  * @freq_table: Optional list of frequencies to support statistics.
  77  * @max_state:  The size of freq_table.
  78  */
  79 struct devfreq_dev_profile {
  80         unsigned long initial_freq;
  81         unsigned int polling_ms;
  82
  83         int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  84         int (*get_dev_status)(struct device *dev,
  85                               struct devfreq_dev_status *stat);
  86         int (*get_cur_freq)(struct device *dev, unsigned long *freq);
  87         void (*exit)(struct device *dev);
  88
  89         unsigned int *freq_table;
  90         unsigned int max_state;
  91 };
  92
  93 /**
  94  * struct devfreq_governor - Devfreq policy governor
  95  * @node:               list node - contains registered devfreq governors
  96  * @name:               Governor's name
  97  * @get_target_freq:    Returns desired operating frequency for the device.
  98  *                      Basically, get_target_freq will run
  99  *                      devfreq_dev_profile.get_dev_status() to get the
 100  *                      status of the device (load = busy_time / total_time).
 101  *                      If no_central_polling is set, this callback is called
 102  *                      only with update_devfreq() notified by OPP.
 103  * @event_handler:      Callback for devfreq core framework to notify events
 104  *                      to governors. Events include per device governor
 105  *                      init and exit, opp changes out of devfreq, suspend
 106  *                      and resume of per device devfreq during device idle.
 107  *
 108  * Note that the callbacks are called with devfreq->lock locked by devfreq.
 109  */
 110 struct devfreq_governor {
 111         struct list_head node;
 112
 113         const char name[DEVFREQ_NAME_LEN];
 114         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 115         int (*event_handler)(struct devfreq *devfreq,
 116                                 unsigned int event, void *data);
 117 };
 118
 119 /**
 120  * struct devfreq - Device devfreq structure
 121  * @node:       list node - contains the devices with devfreq that have been
 122  *              registered.
 123  * @lock:       a mutex to protect accessing devfreq.
 124  * @dev:        device registered by devfreq class. dev.parent is the device
 125  *              using devfreq.
 126  * @profile:    device-specific devfreq profile
 127  * @governor:   method how to choose frequency based on the usage.
 128  * @governor_name:      devfreq governor name for use with this devfreq
 129  * @nb:         notifier block used to notify devfreq object that it should
 130  *              reevaluate operable frequencies. Devfreq users may use
 131  *              devfreq.nb to the corresponding register notifier call chain.
 132  * @work:       delayed work for load monitoring.
 133  * @previous_freq:      previously configured frequency value.
 134  * @data:       Private data of the governor. The devfreq framework does not
 135  *              touch this.
 136  * @min_freq:   Limit minimum frequency requested by user (0: none)
 137  * @max_freq:   Limit maximum frequency requested by user (0: none)
 138  * @stop_polling:        devfreq polling status of a device.
 139  * @total_trans:        Number of devfreq transitions
 140  * @trans_table:        Statistics of devfreq transitions
 141  * @time_in_state:      Statistics of devfreq states
 142  * @last_stat_updated:  The last time stat updated
 143  *
 144  * This structure stores the devfreq information for a give device.
 145  *
 146  * Note that when a governor accesses entries in struct devfreq in its
 147  * functions except for the context of callbacks defined in struct
 148  * devfreq_governor, the governor should protect its access with the
 149  * struct mutex lock in struct devfreq. A governor may use this mutex
 150  * to protect its own private data in void *data as well.
 151  */
 152 struct devfreq {
 153         struct list_head node;
 154
 155         struct mutex lock;
 156         struct device dev;
 157         struct devfreq_dev_profile *profile;
 158         const struct devfreq_governor *governor;
 159         char governor_name[DEVFREQ_NAME_LEN];
 160         struct notifier_block nb;
 161         struct delayed_work work;
 162
 163         unsigned long previous_freq;
 164
 165         void *data; /* private data for governors */
 166
 167         unsigned long min_freq;
 168         unsigned long max_freq;
 169         bool stop_polling;
 170
 171         /* information for device freqeuncy transition */
 172         unsigned int total_trans;
 173         unsigned int *trans_table;
 174         unsigned long *time_in_state;
 175         unsigned long last_stat_updated;
 176 };
 177
 178 #if defined(CONFIG_PM_DEVFREQ)
 179 extern struct devfreq *devfreq_add_device(struct device *dev,
 180                                   struct devfreq_dev_profile *profile,
 181                                   const char *governor_name,
 182                                   void *data);
 183 extern int devfreq_remove_device(struct devfreq *devfreq);
 184 extern int devfreq_suspend_device(struct devfreq *devfreq);
 185 extern int devfreq_resume_device(struct devfreq *devfreq);
 186
 187 /* Helper functions for devfreq user device driver with OPP. */
 188 extern struct opp *devfreq_recommended_opp(struct device *dev,
 189                                            unsigned long *freq, u32 flags);
 190 extern int devfreq_register_opp_notifier(struct device *dev,
 191                                          struct devfreq *devfreq);
 192 extern int devfreq_unregister_opp_notifier(struct device *dev,
 193                                            struct devfreq *devfreq);
 194
 195 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 196 /**
 197  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 198  *      and devfreq_add_device
 199  * @upthreshold:        If the load is over this value, the frequency jumps.
 200  *                      Specify 0 to use the default. Valid value = 0 to 100.
 201  * @downdifferential:   If the load is under upthreshold - downdifferential,
 202  *                      the governor may consider slowing the frequency down.
 203  *                      Specify 0 to use the default. Valid value = 0 to 100.
 204  *                      downdifferential < upthreshold must hold.
 205  *
 206  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 207  * the governor uses the default values.
 208  */
 209 struct devfreq_simple_ondemand_data {
 210         unsigned int upthreshold;
 211         unsigned int downdifferential;
 212 };
 213 #endif
 214
 215 #else /* !CONFIG_PM_DEVFREQ */
 216 static inline struct devfreq *devfreq_add_device(struct device *dev,
 217                                           struct devfreq_dev_profile *profile,
 218                                           const char *governor_name,
 219                                           void *data)
 220 {
 221         return NULL;
 222 }
 223
 224 static inline int devfreq_remove_device(struct devfreq *devfreq)
 225 {
 226         return 0;
 227 }
 228
 229 static inline int devfreq_suspend_device(struct devfreq *devfreq)
 230 {
 231         return 0;
 232 }
 233
 234 static inline int devfreq_resume_device(struct devfreq *devfreq)
 235 {
 236         return 0;
 237 }
 238
 239 static inline struct opp *devfreq_recommended_opp(struct device *dev,
 240                                            unsigned long *freq, u32 flags)
 241 {
 242         return ERR_PTR(-EINVAL);
 243 }
 244
 245 static inline int devfreq_register_opp_notifier(struct device *dev,
 246                                          struct devfreq *devfreq)
 247 {
 248         return -EINVAL;
 249 }
 250
 251 static inline int devfreq_unregister_opp_notifier(struct device *dev,
 252                                            struct devfreq *devfreq)
 253 {
 254         return -EINVAL;
 255 }
 256
 257 #endif /* CONFIG_PM_DEVFREQ */
 258
 259 #endif /* __LINUX_DEVFREQ_H__ */