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  * @exit                An optional callback that is called when devfreq
  70  *                      is removing the devfreq object due to error or
  71  *                      from devfreq_remove_device() call. If the user
  72  *                      has registered devfreq->nb at a notifier-head,
  73  *                      this is the time to unregister it.
  74  */
  75 struct devfreq_dev_profile {
  76         unsigned long initial_freq;
  77         unsigned int polling_ms;
  78
  79         int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  80         int (*get_dev_status)(struct device *dev,
  81                               struct devfreq_dev_status *stat);
  82         void (*exit)(struct device *dev);
  83 };
  84
  85 /**
  86  * struct devfreq_governor - Devfreq policy governor
  87  * @name                Governor's name
  88  * @get_target_freq     Returns desired operating frequency for the device.
  89  *                      Basically, get_target_freq will run
  90  *                      devfreq_dev_profile.get_dev_status() to get the
  91  *                      status of the device (load = busy_time / total_time).
  92  *                      If no_central_polling is set, this callback is called
  93  *                      only with update_devfreq() notified by OPP.
  94  * @init                Called when the devfreq is being attached to a device
  95  * @exit                Called when the devfreq is being removed from a
  96  *                      device. Governor should stop any internal routines
  97  *                      before return because related data may be
  98  *                      freed after exit().
  99  * @no_central_polling  Do not use devfreq's central polling mechanism.
 100  *                      When this is set, devfreq will not call
 101  *                      get_target_freq with devfreq_monitor(). However,
 102  *                      devfreq will call get_target_freq with
 103  *                      devfreq_update() notified by OPP framework.
 104  *
 105  * Note that the callbacks are called with devfreq->lock locked by devfreq.
 106  */
 107 struct devfreq_governor {
 108         const char name[DEVFREQ_NAME_LEN];
 109         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 110         int (*init)(struct devfreq *this);
 111         void (*exit)(struct devfreq *this);
 112         const bool no_central_polling;
 113 };
 114
 115 /**
 116  * struct devfreq - Device devfreq structure
 117  * @node        list node - contains the devices with devfreq that have been
 118  *              registered.
 119  * @lock        a mutex to protect accessing devfreq.
 120  * @dev         device registered by devfreq class. dev.parent is the device
 121  *              using devfreq.
 122  * @profile     device-specific devfreq profile
 123  * @governor    method how to choose frequency based on the usage.
 124  * @nb          notifier block used to notify devfreq object that it should
 125  *              reevaluate operable frequencies. Devfreq users may use
 126  *              devfreq.nb to the corresponding register notifier call chain.
 127  * @polling_jiffies     interval in jiffies.
 128  * @previous_freq       previously configured frequency value.
 129  * @next_polling        the number of remaining jiffies to poll with
 130  *                      "devfreq_monitor" executions to reevaluate
 131  *                      frequency/voltage of the device. Set by
 132  *                      profile's polling_ms interval.
 133  * @data        Private data of the governor. The devfreq framework does not
 134  *              touch this.
 135  * @being_removed       a flag to mark that this object is being removed in
 136  *                      order to prevent trying to remove the object multiple times.
 137  * @min_freq    Limit minimum frequency requested by user (0: none)
 138  * @max_freq    Limit maximum frequency requested by user (0: none)
 139  *
 140  * This structure stores the devfreq information for a give device.
 141  *
 142  * Note that when a governor accesses entries in struct devfreq in its
 143  * functions except for the context of callbacks defined in struct
 144  * devfreq_governor, the governor should protect its access with the
 145  * struct mutex lock in struct devfreq. A governor may use this mutex
 146  * to protect its own private data in void *data as well.
 147  */
 148 struct devfreq {
 149         struct list_head node;
 150
 151         struct mutex lock;
 152         struct device dev;
 153         struct devfreq_dev_profile *profile;
 154         const struct devfreq_governor *governor;
 155         struct notifier_block nb;
 156
 157         unsigned long polling_jiffies;
 158         unsigned long previous_freq;
 159         unsigned int next_polling;
 160
 161         void *data; /* private data for governors */
 162
 163         bool being_removed;
 164
 165         unsigned long min_freq;
 166         unsigned long max_freq;
 167 };
 168
 169 #if defined(CONFIG_PM_DEVFREQ)
 170 extern struct devfreq *devfreq_add_device(struct device *dev,
 171                                   struct devfreq_dev_profile *profile,
 172                                   const struct devfreq_governor *governor,
 173                                   void *data);
 174 extern int devfreq_remove_device(struct devfreq *devfreq);
 175
 176 /* Helper functions for devfreq user device driver with OPP. */
 177 extern struct opp *devfreq_recommended_opp(struct device *dev,
 178                                            unsigned long *freq, u32 flags);
 179 extern int devfreq_register_opp_notifier(struct device *dev,
 180                                          struct devfreq *devfreq);
 181 extern int devfreq_unregister_opp_notifier(struct device *dev,
 182                                            struct devfreq *devfreq);
 183
 184 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
 185 extern const struct devfreq_governor devfreq_powersave;
 186 #endif
 187 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
 188 extern const struct devfreq_governor devfreq_performance;
 189 #endif
 190 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
 191 extern const struct devfreq_governor devfreq_userspace;
 192 #endif
 193 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
 194 extern const struct devfreq_governor devfreq_simple_ondemand;
 195 /**
 196  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 197  *      and devfreq_add_device
 198  * @ upthreshold        If the load is over this value, the frequency jumps.
 199  *                      Specify 0 to use the default. Valid value = 0 to 100.
 200  * @ downdifferential   If the load is under upthreshold - downdifferential,
 201  *                      the governor may consider slowing the frequency down.
 202  *                      Specify 0 to use the default. Valid value = 0 to 100.
 203  *                      downdifferential < upthreshold must hold.
 204  *
 205  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 206  * the governor uses the default values.
 207  */
 208 struct devfreq_simple_ondemand_data {
 209         unsigned int upthreshold;
 210         unsigned int downdifferential;
 211 };
 212 #endif
 213
 214 #else /* !CONFIG_PM_DEVFREQ */
 215 static struct devfreq *devfreq_add_device(struct device *dev,
 216                                           struct devfreq_dev_profile *profile,
 217                                           struct devfreq_governor *governor,
 218                                           void *data)
 219 {
 220         return NULL;
 221 }
 222
 223 static int devfreq_remove_device(struct devfreq *devfreq)
 224 {
 225         return 0;
 226 }
 227
 228 static struct opp *devfreq_recommended_opp(struct device *dev,
 229                                            unsigned long *freq, u32 flags)
 230 {
 231         return -EINVAL;
 232 }
 233
 234 static int devfreq_register_opp_notifier(struct device *dev,
 235                                          struct devfreq *devfreq)
 236 {
 237         return -EINVAL;
 238 }
 239
 240 static int devfreq_unregister_opp_notifier(struct device *dev,
 241                                            struct devfreq *devfreq)
 242 {
 243         return -EINVAL;
 244 }
 245
 246 #define devfreq_powersave       NULL
 247 #define devfreq_performance     NULL
 248 #define devfreq_userspace       NULL
 249 #define devfreq_simple_ondemand NULL
 250
 251 #endif /* CONFIG_PM_DEVFREQ */
 252
 253 #endif /* __LINUX_DEVFREQ_H__ */