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 * @init Called when the devfreq is being attached to a device 95 * @exit Called when the devfreq is being removed from a 96 * device. Governor should stop any internal routines 97 * before return because related data may be 98 * freed after exit(). 99 * @no_central_polling Do not use devfreq's central polling mechanism. 100 * When this is set, devfreq will not call 101 * get_target_freq with devfreq_monitor(). However, 102 * devfreq will call get_target_freq with 103 * devfreq_update() notified by OPP framework. 104 * 105 * Note that the callbacks are called with devfreq->lock locked by devfreq. 106 */ 107 struct devfreq_governor { 108 const char name[DEVFREQ_NAME_LEN]; 109 int (*get_target_freq)(struct devfreq *this, unsigned long *freq); 110 int (*init)(struct devfreq *this); 111 void (*exit)(struct devfreq *this); 112 const bool no_central_polling; 113 }; 114 115 /** 116 * struct devfreq - Device devfreq structure 117 * @node list node - contains the devices with devfreq that have been 118 * registered. 119 * @lock a mutex to protect accessing devfreq. 120 * @dev device registered by devfreq class. dev.parent is the device 121 * using devfreq. 122 * @profile device-specific devfreq profile 123 * @governor method how to choose frequency based on the usage. 124 * @nb notifier block used to notify devfreq object that it should 125 * reevaluate operable frequencies. Devfreq users may use 126 * devfreq.nb to the corresponding register notifier call chain. 127 * @polling_jiffies interval in jiffies. 128 * @previous_freq previously configured frequency value. 129 * @next_polling the number of remaining jiffies to poll with 130 * "devfreq_monitor" executions to reevaluate 131 * frequency/voltage of the device. Set by 132 * profile's polling_ms interval. 133 * @data Private data of the governor. The devfreq framework does not 134 * touch this. 135 * @being_removed a flag to mark that this object is being removed in 136 * order to prevent trying to remove the object multiple times. 137 * @min_freq Limit minimum frequency requested by user (0: none) 138 * @max_freq Limit maximum frequency requested by user (0: none) 139 * 140 * This structure stores the devfreq information for a give device. 141 * 142 * Note that when a governor accesses entries in struct devfreq in its 143 * functions except for the context of callbacks defined in struct 144 * devfreq_governor, the governor should protect its access with the 145 * struct mutex lock in struct devfreq. A governor may use this mutex 146 * to protect its own private data in void *data as well. 147 */ 148 struct devfreq { 149 struct list_head node; 150 151 struct mutex lock; 152 struct device dev; 153 struct devfreq_dev_profile *profile; 154 const struct devfreq_governor *governor; 155 struct notifier_block nb; 156 157 unsigned long polling_jiffies; 158 unsigned long previous_freq; 159 unsigned int next_polling; 160 161 void *data; /* private data for governors */ 162 163 bool being_removed; 164 165 unsigned long min_freq; 166 unsigned long max_freq; 167 }; 168 169 #if defined(CONFIG_PM_DEVFREQ) 170 extern struct devfreq *devfreq_add_device(struct device *dev, 171 struct devfreq_dev_profile *profile, 172 const struct devfreq_governor *governor, 173 void *data); 174 extern int devfreq_remove_device(struct devfreq *devfreq); 175 176 /* Helper functions for devfreq user device driver with OPP. */ 177 extern struct opp *devfreq_recommended_opp(struct device *dev, 178 unsigned long *freq, u32 flags); 179 extern int devfreq_register_opp_notifier(struct device *dev, 180 struct devfreq *devfreq); 181 extern int devfreq_unregister_opp_notifier(struct device *dev, 182 struct devfreq *devfreq); 183 184 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE 185 extern const struct devfreq_governor devfreq_powersave; 186 #endif 187 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE 188 extern const struct devfreq_governor devfreq_performance; 189 #endif 190 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE 191 extern const struct devfreq_governor devfreq_userspace; 192 #endif 193 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND 194 extern const struct devfreq_governor devfreq_simple_ondemand; 195 /** 196 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq 197 * and devfreq_add_device 198 * @ upthreshold If the load is over this value, the frequency jumps. 199 * Specify 0 to use the default. Valid value = 0 to 100. 200 * @ downdifferential If the load is under upthreshold - downdifferential, 201 * the governor may consider slowing the frequency down. 202 * Specify 0 to use the default. Valid value = 0 to 100. 203 * downdifferential < upthreshold must hold. 204 * 205 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor, 206 * the governor uses the default values. 207 */ 208 struct devfreq_simple_ondemand_data { 209 unsigned int upthreshold; 210 unsigned int downdifferential; 211 }; 212 #endif 213 214 #else /* !CONFIG_PM_DEVFREQ */ 215 static struct devfreq *devfreq_add_device(struct device *dev, 216 struct devfreq_dev_profile *profile, 217 struct devfreq_governor *governor, 218 void *data) 219 { 220 return NULL; 221 } 222 223 static int devfreq_remove_device(struct devfreq *devfreq) 224 { 225 return 0; 226 } 227 228 static struct opp *devfreq_recommended_opp(struct device *dev, 229 unsigned long *freq, u32 flags) 230 { 231 return -EINVAL; 232 } 233 234 static int devfreq_register_opp_notifier(struct device *dev, 235 struct devfreq *devfreq) 236 { 237 return -EINVAL; 238 } 239 240 static int devfreq_unregister_opp_notifier(struct device *dev, 241 struct devfreq *devfreq) 242 { 243 return -EINVAL; 244 } 245 246 #define devfreq_powersave NULL 247 #define devfreq_performance NULL 248 #define devfreq_userspace NULL 249 #define devfreq_simple_ondemand NULL 250 251 #endif /* CONFIG_PM_DEVFREQ */ 252 253 #endif /* __LINUX_DEVFREQ_H__ */ 254