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  * struct devfreq_dev_profile - Devfreq's user device profile
  49  * @initial_freq        The operating frequency when devfreq_add_device() is
  50  *                      called.
  51  * @polling_ms          The polling interval in ms. 0 disables polling.
  52  * @target              The device should set its operating frequency at
  53  *                      freq or lowest-upper-than-freq value. If freq is
  54  *                      higher than any operable frequency, set maximum.
  55  *                      Before returning, target function should set
  56  *                      freq at the current frequency.
  57  * @get_dev_status      The device should provide the current performance
  58  *                      status to devfreq, which is used by governors.
  59  * @exit                An optional callback that is called when devfreq
  60  *                      is removing the devfreq object due to error or
  61  *                      from devfreq_remove_device() call. If the user
  62  *                      has registered devfreq->nb at a notifier-head,
  63  *                      this is the time to unregister it.
  64  */
  65 struct devfreq_dev_profile {
  66         unsigned long initial_freq;
  67         unsigned int polling_ms;
  68
  69         int (*target)(struct device *dev, unsigned long *freq);
  70         int (*get_dev_status)(struct device *dev,
  71                               struct devfreq_dev_status *stat);
  72         void (*exit)(struct device *dev);
  73 };
  74
  75 /**
  76  * struct devfreq_governor - Devfreq policy governor
  77  * @name                Governor's name
  78  * @get_target_freq     Returns desired operating frequency for the device.
  79  *                      Basically, get_target_freq will run
  80  *                      devfreq_dev_profile.get_dev_status() to get the
  81  *                      status of the device (load = busy_time / total_time).
  82  *                      If no_central_polling is set, this callback is called
  83  *                      only with update_devfreq() notified by OPP.
  84  * @init                Called when the devfreq is being attached to a device
  85  * @exit                Called when the devfreq is being removed from a
  86  *                      device. Governor should stop any internal routines
  87  *                      before return because related data may be
  88  *                      freed after exit().
  89  * @no_central_polling  Do not use devfreq's central polling mechanism.
  90  *                      When this is set, devfreq will not call
  91  *                      get_target_freq with devfreq_monitor(). However,
  92  *                      devfreq will call get_target_freq with
  93  *                      devfreq_update() notified by OPP framework.
  94  *
  95  * Note that the callbacks are called with devfreq->lock locked by devfreq.
  96  */
  97 struct devfreq_governor {
  98         const char name[DEVFREQ_NAME_LEN];
  99         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 100         int (*init)(struct devfreq *this);
 101         void (*exit)(struct devfreq *this);
 102         const bool no_central_polling;
 103 };
 104
 105 /**
 106  * struct devfreq - Device devfreq structure
 107  * @node        list node - contains the devices with devfreq that have been
 108  *              registered.
 109  * @lock        a mutex to protect accessing devfreq.
 110  * @dev         device registered by devfreq class. dev.parent is the device
 111  *              using devfreq.
 112  * @profile     device-specific devfreq profile
 113  * @governor    method how to choose frequency based on the usage.
 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  * @polling_jiffies     interval in jiffies.
 118  * @previous_freq       previously configured frequency value.
 119  * @next_polling        the number of remaining jiffies to poll with
 120  *                      "devfreq_monitor" executions to reevaluate
 121  *                      frequency/voltage of the device. Set by
 122  *                      profile's polling_ms interval.
 123  * @data        Private data of the governor. The devfreq framework does not
 124  *              touch this.
 125  * @being_removed       a flag to mark that this object is being removed in
 126  *                      order to prevent trying to remove the object multiple times.
 127  *
 128  * This structure stores the devfreq information for a give device.
 129  *
 130  * Note that when a governor accesses entries in struct devfreq in its
 131  * functions except for the context of callbacks defined in struct
 132  * devfreq_governor, the governor should protect its access with the
 133  * struct mutex lock in struct devfreq. A governor may use this mutex
 134  * to protect its own private data in void *data as well.
 135  */
 136 struct devfreq {
 137         struct list_head node;
 138
 139         struct mutex lock;
 140         struct device dev;
 141         struct devfreq_dev_profile *profile;
 142         const struct devfreq_governor *governor;
 143         struct notifier_block nb;
 144
 145         unsigned long polling_jiffies;
 146         unsigned long previous_freq;
 147         unsigned int next_polling;
 148
 149         void *data; /* private data for governors */
 150
 151         bool being_removed;
 152 };
 153
 154 #if defined(CONFIG_PM_DEVFREQ)
 155 extern struct devfreq *devfreq_add_device(struct device *dev,
 156                                   struct devfreq_dev_profile *profile,
 157                                   const struct devfreq_governor *governor,
 158                                   void *data);
 159 extern int devfreq_remove_device(struct devfreq *devfreq);
 160
 161 /* Helper functions for devfreq user device driver with OPP. */
 162 extern struct opp *devfreq_recommended_opp(struct device *dev,
 163                                            unsigned long *freq);
 164 extern int devfreq_register_opp_notifier(struct device *dev,
 165                                          struct devfreq *devfreq);
 166 extern int devfreq_unregister_opp_notifier(struct device *dev,
 167                                            struct devfreq *devfreq);
 168
 169 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
 170 extern const struct devfreq_governor devfreq_powersave;
 171 #endif
 172 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
 173 extern const struct devfreq_governor devfreq_performance;
 174 #endif
 175 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
 176 extern const struct devfreq_governor devfreq_userspace;
 177 #endif
 178 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
 179 extern const struct devfreq_governor devfreq_simple_ondemand;
 180 /**
 181  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 182  *      and devfreq_add_device
 183  * @ upthreshold        If the load is over this value, the frequency jumps.
 184  *                      Specify 0 to use the default. Valid value = 0 to 100.
 185  * @ downdifferential   If the load is under upthreshold - downdifferential,
 186  *                      the governor may consider slowing the frequency down.
 187  *                      Specify 0 to use the default. Valid value = 0 to 100.
 188  *                      downdifferential < upthreshold must hold.
 189  *
 190  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 191  * the governor uses the default values.
 192  */
 193 struct devfreq_simple_ondemand_data {
 194         unsigned int upthreshold;
 195         unsigned int downdifferential;
 196 };
 197 #endif
 198
 199 #else /* !CONFIG_PM_DEVFREQ */
 200 static struct devfreq *devfreq_add_device(struct device *dev,
 201                                           struct devfreq_dev_profile *profile,
 202                                           struct devfreq_governor *governor,
 203                                           void *data);
 204 {
 205         return NULL;
 206 }
 207
 208 static int devfreq_remove_device(struct devfreq *devfreq);
 209 {
 210         return 0;
 211 }
 212
 213 static struct opp *devfreq_recommended_opp(struct device *dev,
 214                                            unsigned long *freq)
 215 {
 216         return -EINVAL;
 217 }
 218
 219 static int devfreq_register_opp_notifier(struct device *dev,
 220                                          struct devfreq *devfreq)
 221 {
 222         return -EINVAL;
 223 }
 224
 225 static int devfreq_unregister_opp_notifier(struct device *dev,
 226                                            struct devfreq *devfreq)
 227 {
 228         return -EINVAL;
 229 }
 230
 231 #define devfreq_powersave       NULL
 232 #define devfreq_performance     NULL
 233 #define devfreq_userspace       NULL
 234 #define devfreq_simple_ondemand NULL
 235
 236 #endif /* CONFIG_PM_DEVFREQ */
 237
 238 #endif /* __LINUX_DEVFREQ_H__ */