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Linux/include/linux/devfreq.h

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  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/pm_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 frequency 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 
185 /* Supposed to be called by PM_SLEEP/PM_RUNTIME callbacks */
186 extern int devfreq_suspend_device(struct devfreq *devfreq);
187 extern int devfreq_resume_device(struct devfreq *devfreq);
188 
189 /* Helper functions for devfreq user device driver with OPP. */
190 extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
191                                            unsigned long *freq, u32 flags);
192 extern int devfreq_register_opp_notifier(struct device *dev,
193                                          struct devfreq *devfreq);
194 extern int devfreq_unregister_opp_notifier(struct device *dev,
195                                            struct devfreq *devfreq);
196 
197 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
198 /**
199  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
200  *      and devfreq_add_device
201  * @upthreshold:        If the load is over this value, the frequency jumps.
202  *                      Specify 0 to use the default. Valid value = 0 to 100.
203  * @downdifferential:   If the load is under upthreshold - downdifferential,
204  *                      the governor may consider slowing the frequency down.
205  *                      Specify 0 to use the default. Valid value = 0 to 100.
206  *                      downdifferential < upthreshold must hold.
207  *
208  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
209  * the governor uses the default values.
210  */
211 struct devfreq_simple_ondemand_data {
212         unsigned int upthreshold;
213         unsigned int downdifferential;
214 };
215 #endif
216 
217 #else /* !CONFIG_PM_DEVFREQ */
218 static inline struct devfreq *devfreq_add_device(struct device *dev,
219                                           struct devfreq_dev_profile *profile,
220                                           const char *governor_name,
221                                           void *data)
222 {
223         return NULL;
224 }
225 
226 static inline int devfreq_remove_device(struct devfreq *devfreq)
227 {
228         return 0;
229 }
230 
231 static inline int devfreq_suspend_device(struct devfreq *devfreq)
232 {
233         return 0;
234 }
235 
236 static inline int devfreq_resume_device(struct devfreq *devfreq)
237 {
238         return 0;
239 }
240 
241 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
242                                            unsigned long *freq, u32 flags)
243 {
244         return ERR_PTR(-EINVAL);
245 }
246 
247 static inline int devfreq_register_opp_notifier(struct device *dev,
248                                          struct devfreq *devfreq)
249 {
250         return -EINVAL;
251 }
252 
253 static inline int devfreq_unregister_opp_notifier(struct device *dev,
254                                            struct devfreq *devfreq)
255 {
256         return -EINVAL;
257 }
258 
259 #endif /* CONFIG_PM_DEVFREQ */
260 
261 #endif /* __LINUX_DEVFREQ_H__ */
262 

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