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 22struct 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 */ 39struct 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. Governors are recommended not to 69 * use this directly. Instead, governors are recommended 70 * to use devfreq_update_stats() along with 71 * devfreq.last_status. 72 * @get_cur_freq: The device should provide the current frequency 73 * at which it is operating. 74 * @exit: An optional callback that is called when devfreq 75 * is removing the devfreq object due to error or 76 * from devfreq_remove_device() call. If the user 77 * has registered devfreq->nb at a notifier-head, 78 * this is the time to unregister it. 79 * @freq_table: Optional list of frequencies to support statistics. 80 * @max_state: The size of freq_table. 81 */ 82struct devfreq_dev_profile { 83 unsigned long initial_freq; 84 unsigned int polling_ms; 85 86 int (*target)(struct device *dev, unsigned long *freq, u32 flags); 87 int (*get_dev_status)(struct device *dev, 88 struct devfreq_dev_status *stat); 89 int (*get_cur_freq)(struct device *dev, unsigned long *freq); 90 void (*exit)(struct device *dev); 91 92 unsigned int *freq_table; 93 unsigned int max_state; 94}; 95 96/** 97 * struct devfreq_governor - Devfreq policy governor 98 * @node: list node - contains registered devfreq governors 99 * @name: Governor's name 100 * @get_target_freq: Returns desired operating frequency for the device. 101 * Basically, get_target_freq will run 102 * devfreq_dev_profile.get_dev_status() to get the 103 * status of the device (load = busy_time / total_time). 104 * If no_central_polling is set, this callback is called 105 * only with update_devfreq() notified by OPP. 106 * @event_handler: Callback for devfreq core framework to notify events 107 * to governors. Events include per device governor 108 * init and exit, opp changes out of devfreq, suspend 109 * and resume of per device devfreq during device idle. 110 * 111 * Note that the callbacks are called with devfreq->lock locked by devfreq. 112 */ 113struct devfreq_governor { 114 struct list_head node; 115 116 const char name[DEVFREQ_NAME_LEN]; 117 int (*get_target_freq)(struct devfreq *this, unsigned long *freq); 118 int (*event_handler)(struct devfreq *devfreq, 119 unsigned int event, void *data); 120}; 121 122/** 123 * struct devfreq - Device devfreq structure 124 * @node: list node - contains the devices with devfreq that have been 125 * registered. 126 * @lock: a mutex to protect accessing devfreq. 127 * @dev: device registered by devfreq class. dev.parent is the device 128 * using devfreq. 129 * @profile: device-specific devfreq profile 130 * @governor: method how to choose frequency based on the usage. 131 * @governor_name: devfreq governor name for use with this devfreq 132 * @nb: notifier block used to notify devfreq object that it should 133 * reevaluate operable frequencies. Devfreq users may use 134 * devfreq.nb to the corresponding register notifier call chain. 135 * @work: delayed work for load monitoring. 136 * @previous_freq: previously configured frequency value. 137 * @data: Private data of the governor. The devfreq framework does not 138 * touch this. 139 * @min_freq: Limit minimum frequency requested by user (0: none) 140 * @max_freq: Limit maximum frequency requested by user (0: none) 141 * @stop_polling: devfreq polling status of a device. 142 * @total_trans: Number of devfreq transitions 143 * @trans_table: Statistics of devfreq transitions 144 * @time_in_state: Statistics of devfreq states 145 * @last_stat_updated: The last time stat updated 146 * 147 * This structure stores the devfreq information for a give device. 148 * 149 * Note that when a governor accesses entries in struct devfreq in its 150 * functions except for the context of callbacks defined in struct 151 * devfreq_governor, the governor should protect its access with the 152 * struct mutex lock in struct devfreq. A governor may use this mutex 153 * to protect its own private data in void *data as well. 154 */ 155struct devfreq { 156 struct list_head node; 157 158 struct mutex lock; 159 struct device dev; 160 struct devfreq_dev_profile *profile; 161 const struct devfreq_governor *governor; 162 char governor_name[DEVFREQ_NAME_LEN]; 163 struct notifier_block nb; 164 struct delayed_work work; 165 166 unsigned long previous_freq; 167 struct devfreq_dev_status last_status; 168 169 void *data; /* private data for governors */ 170 171 unsigned long min_freq; 172 unsigned long max_freq; 173 bool stop_polling; 174 175 /* information for device frequency transition */ 176 unsigned int total_trans; 177 unsigned int *trans_table; 178 unsigned long *time_in_state; 179 unsigned long last_stat_updated; 180}; 181 182#if defined(CONFIG_PM_DEVFREQ) 183extern struct devfreq *devfreq_add_device(struct device *dev, 184 struct devfreq_dev_profile *profile, 185 const char *governor_name, 186 void *data); 187extern int devfreq_remove_device(struct devfreq *devfreq); 188extern struct devfreq *devm_devfreq_add_device(struct device *dev, 189 struct devfreq_dev_profile *profile, 190 const char *governor_name, 191 void *data); 192extern void devm_devfreq_remove_device(struct device *dev, 193 struct devfreq *devfreq); 194 195/* Supposed to be called by PM callbacks */ 196extern int devfreq_suspend_device(struct devfreq *devfreq); 197extern int devfreq_resume_device(struct devfreq *devfreq); 198 199/* Helper functions for devfreq user device driver with OPP. */ 200extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev, 201 unsigned long *freq, u32 flags); 202extern int devfreq_register_opp_notifier(struct device *dev, 203 struct devfreq *devfreq); 204extern int devfreq_unregister_opp_notifier(struct device *dev, 205 struct devfreq *devfreq); 206extern int devm_devfreq_register_opp_notifier(struct device *dev, 207 struct devfreq *devfreq); 208extern void devm_devfreq_unregister_opp_notifier(struct device *dev, 209 struct devfreq *devfreq); 210 211/** 212 * devfreq_update_stats() - update the last_status pointer in struct devfreq 213 * @df: the devfreq instance whose status needs updating 214 * 215 * Governors are recommended to use this function along with last_status, 216 * which allows other entities to reuse the last_status without affecting 217 * the values fetched later by governors. 218 */ 219static inline int devfreq_update_stats(struct devfreq *df) 220{ 221 return df->profile->get_dev_status(df->dev.parent, &df->last_status); 222} 223 224#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) 225/** 226 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq 227 * and devfreq_add_device 228 * @upthreshold: If the load is over this value, the frequency jumps. 229 * Specify 0 to use the default. Valid value = 0 to 100. 230 * @downdifferential: If the load is under upthreshold - downdifferential, 231 * the governor may consider slowing the frequency down. 232 * Specify 0 to use the default. Valid value = 0 to 100. 233 * downdifferential < upthreshold must hold. 234 * 235 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor, 236 * the governor uses the default values. 237 */ 238struct devfreq_simple_ondemand_data { 239 unsigned int upthreshold; 240 unsigned int downdifferential; 241}; 242#endif 243 244#else /* !CONFIG_PM_DEVFREQ */ 245static inline struct devfreq *devfreq_add_device(struct device *dev, 246 struct devfreq_dev_profile *profile, 247 const char *governor_name, 248 void *data) 249{ 250 return ERR_PTR(-ENOSYS); 251} 252 253static inline int devfreq_remove_device(struct devfreq *devfreq) 254{ 255 return 0; 256} 257 258static inline struct devfreq *devm_devfreq_add_device(struct device *dev, 259 struct devfreq_dev_profile *profile, 260 const char *governor_name, 261 void *data) 262{ 263 return ERR_PTR(-ENOSYS); 264} 265 266static inline void devm_devfreq_remove_device(struct device *dev, 267 struct devfreq *devfreq) 268{ 269} 270 271static inline int devfreq_suspend_device(struct devfreq *devfreq) 272{ 273 return 0; 274} 275 276static inline int devfreq_resume_device(struct devfreq *devfreq) 277{ 278 return 0; 279} 280 281static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev, 282 unsigned long *freq, u32 flags) 283{ 284 return ERR_PTR(-EINVAL); 285} 286 287static inline int devfreq_register_opp_notifier(struct device *dev, 288 struct devfreq *devfreq) 289{ 290 return -EINVAL; 291} 292 293static inline int devfreq_unregister_opp_notifier(struct device *dev, 294 struct devfreq *devfreq) 295{ 296 return -EINVAL; 297} 298 299static inline int devm_devfreq_register_opp_notifier(struct device *dev, 300 struct devfreq *devfreq) 301{ 302 return -EINVAL; 303} 304 305static inline void devm_devfreq_unregister_opp_notifier(struct device *dev, 306 struct devfreq *devfreq) 307{ 308} 309 310static inline int devfreq_update_stats(struct devfreq *df) 311{ 312 return -EINVAL; 313} 314#endif /* CONFIG_PM_DEVFREQ */ 315 316#endif /* __LINUX_DEVFREQ_H__ */ 317