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  * @event_handler       Callback for devfreq core framework to notify events
  95  *                      to governors. Events include per device governor
  96  *                      init and exit, opp changes out of devfreq, suspend
  97  *                      and resume of per device devfreq during device idle.
  98  *
  99  * Note that the callbacks are called with devfreq->lock locked by devfreq.
 100  */
 101 struct devfreq_governor {
 102         const char name[DEVFREQ_NAME_LEN];
 103         int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 104         int (*event_handler)(struct devfreq *devfreq,
 105                                 unsigned int event, void *data);
 106 };
 107
 108 /**
 109  * struct devfreq - Device devfreq structure
 110  * @node        list node - contains the devices with devfreq that have been
 111  *              registered.
 112  * @lock        a mutex to protect accessing devfreq.
 113  * @dev         device registered by devfreq class. dev.parent is the device
 114  *              using devfreq.
 115  * @profile     device-specific devfreq profile
 116  * @governor    method how to choose frequency based on the usage.
 117  * @nb          notifier block used to notify devfreq object that it should
 118  *              reevaluate operable frequencies. Devfreq users may use
 119  *              devfreq.nb to the corresponding register notifier call chain.
 120  * @work        delayed work for load monitoring.
 121  * @previous_freq       previously configured frequency value.
 122  * @data        Private data of the governor. The devfreq framework does not
 123  *              touch this.
 124  * @min_freq    Limit minimum frequency requested by user (0: none)
 125  * @max_freq    Limit maximum frequency requested by user (0: none)
 126  * @stop_polling         devfreq polling status of a device.
 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         struct delayed_work work;
 145
 146         unsigned long previous_freq;
 147
 148         void *data; /* private data for governors */
 149
 150         unsigned long min_freq;
 151         unsigned long max_freq;
 152         bool stop_polling;
 153 };
 154
 155 #if defined(CONFIG_PM_DEVFREQ)
 156 extern struct devfreq *devfreq_add_device(struct device *dev,
 157                                   struct devfreq_dev_profile *profile,
 158                                   const struct devfreq_governor *governor,
 159                                   void *data);
 160 extern int devfreq_remove_device(struct devfreq *devfreq);
 161 extern int devfreq_suspend_device(struct devfreq *devfreq);
 162 extern int devfreq_resume_device(struct devfreq *devfreq);
 163
 164 /* Helper functions for devfreq user device driver with OPP. */
 165 extern struct opp *devfreq_recommended_opp(struct device *dev,
 166                                            unsigned long *freq, u32 flags);
 167 extern int devfreq_register_opp_notifier(struct device *dev,
 168                                          struct devfreq *devfreq);
 169 extern int devfreq_unregister_opp_notifier(struct device *dev,
 170                                            struct devfreq *devfreq);
 171
 172 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
 173 extern const struct devfreq_governor devfreq_powersave;
 174 #endif
 175 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
 176 extern const struct devfreq_governor devfreq_performance;
 177 #endif
 178 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
 179 extern const struct devfreq_governor devfreq_userspace;
 180 #endif
 181 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
 182 extern const struct devfreq_governor devfreq_simple_ondemand;
 183 /**
 184  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
 185  *      and devfreq_add_device
 186  * @ upthreshold        If the load is over this value, the frequency jumps.
 187  *                      Specify 0 to use the default. Valid value = 0 to 100.
 188  * @ downdifferential   If the load is under upthreshold - downdifferential,
 189  *                      the governor may consider slowing the frequency down.
 190  *                      Specify 0 to use the default. Valid value = 0 to 100.
 191  *                      downdifferential < upthreshold must hold.
 192  *
 193  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
 194  * the governor uses the default values.
 195  */
 196 struct devfreq_simple_ondemand_data {
 197         unsigned int upthreshold;
 198         unsigned int downdifferential;
 199 };
 200 #endif
 201
 202 #else /* !CONFIG_PM_DEVFREQ */
 203 static struct devfreq *devfreq_add_device(struct device *dev,
 204                                           struct devfreq_dev_profile *profile,
 205                                           struct devfreq_governor *governor,
 206                                           void *data)
 207 {
 208         return NULL;
 209 }
 210
 211 static int devfreq_remove_device(struct devfreq *devfreq)
 212 {
 213         return 0;
 214 }
 215
 216 static int devfreq_suspend_device(struct devfreq *devfreq)
 217 {
 218         return 0;
 219 }
 220
 221 static int devfreq_resume_device(struct devfreq *devfreq)
 222 {
 223         return 0;
 224 }
 225
 226 static struct opp *devfreq_recommended_opp(struct device *dev,
 227                                            unsigned long *freq, u32 flags)
 228 {
 229         return -EINVAL;
 230 }
 231
 232 static int devfreq_register_opp_notifier(struct device *dev,
 233                                          struct devfreq *devfreq)
 234 {
 235         return -EINVAL;
 236 }
 237
 238 static int devfreq_unregister_opp_notifier(struct device *dev,
 239                                            struct devfreq *devfreq)
 240 {
 241         return -EINVAL;
 242 }
 243
 244 #define devfreq_powersave       NULL
 245 #define devfreq_performance     NULL
 246 #define devfreq_userspace       NULL
 247 #define devfreq_simple_ondemand NULL
 248
 249 #endif /* CONFIG_PM_DEVFREQ */
 250
 251 #endif /* __LINUX_DEVFREQ_H__ */