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