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 * struct devfreq_dev_profile - Devfreq's user device profile 49 * @initial_freq The operating frequency when devfreq_add_device() is 50 * called. 51 * @polling_ms The polling interval in ms. 0 disables polling. 52 * @target The device should set its operating frequency at 53 * freq or lowest-upper-than-freq value. If freq is 54 * higher than any operable frequency, set maximum. 55 * Before returning, target function should set 56 * freq at the current frequency. 57 * @get_dev_status The device should provide the current performance 58 * status to devfreq, which is used by governors. 59 * @exit An optional callback that is called when devfreq 60 * is removing the devfreq object due to error or 61 * from devfreq_remove_device() call. If the user 62 * has registered devfreq->nb at a notifier-head, 63 * this is the time to unregister it. 64 */ 65 struct devfreq_dev_profile { 66 unsigned long initial_freq; 67 unsigned int polling_ms; 68 69 int (*target)(struct device *dev, unsigned long *freq); 70 int (*get_dev_status)(struct device *dev, 71 struct devfreq_dev_status *stat); 72 void (*exit)(struct device *dev); 73 }; 74 75 /** 76 * struct devfreq_governor - Devfreq policy governor 77 * @name Governor's name 78 * @get_target_freq Returns desired operating frequency for the device. 79 * Basically, get_target_freq will run 80 * devfreq_dev_profile.get_dev_status() to get the 81 * status of the device (load = busy_time / total_time). 82 * If no_central_polling is set, this callback is called 83 * only with update_devfreq() notified by OPP. 84 * @init Called when the devfreq is being attached to a device 85 * @exit Called when the devfreq is being removed from a 86 * device. Governor should stop any internal routines 87 * before return because related data may be 88 * freed after exit(). 89 * @no_central_polling Do not use devfreq's central polling mechanism. 90 * When this is set, devfreq will not call 91 * get_target_freq with devfreq_monitor(). However, 92 * devfreq will call get_target_freq with 93 * devfreq_update() notified by OPP framework. 94 * 95 * Note that the callbacks are called with devfreq->lock locked by devfreq. 96 */ 97 struct devfreq_governor { 98 const char name[DEVFREQ_NAME_LEN]; 99 int (*get_target_freq)(struct devfreq *this, unsigned long *freq); 100 int (*init)(struct devfreq *this); 101 void (*exit)(struct devfreq *this); 102 const bool no_central_polling; 103 }; 104 105 /** 106 * struct devfreq - Device devfreq structure 107 * @node list node - contains the devices with devfreq that have been 108 * registered. 109 * @lock a mutex to protect accessing devfreq. 110 * @dev device registered by devfreq class. dev.parent is the device 111 * using devfreq. 112 * @profile device-specific devfreq profile 113 * @governor method how to choose frequency based on the usage. 114 * @nb notifier block used to notify devfreq object that it should 115 * reevaluate operable frequencies. Devfreq users may use 116 * devfreq.nb to the corresponding register notifier call chain. 117 * @polling_jiffies interval in jiffies. 118 * @previous_freq previously configured frequency value. 119 * @next_polling the number of remaining jiffies to poll with 120 * "devfreq_monitor" executions to reevaluate 121 * frequency/voltage of the device. Set by 122 * profile's polling_ms interval. 123 * @data Private data of the governor. The devfreq framework does not 124 * touch this. 125 * @being_removed a flag to mark that this object is being removed in 126 * order to prevent trying to remove the object multiple times. 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; 144 145 unsigned long polling_jiffies; 146 unsigned long previous_freq; 147 unsigned int next_polling; 148 149 void *data; /* private data for governors */ 150 151 bool being_removed; 152 }; 153 154 #if defined(CONFIG_PM_DEVFREQ) 155 extern struct devfreq *devfreq_add_device(struct device *dev, 156 struct devfreq_dev_profile *profile, 157 const struct devfreq_governor *governor, 158 void *data); 159 extern int devfreq_remove_device(struct devfreq *devfreq); 160 161 /* Helper functions for devfreq user device driver with OPP. */ 162 extern struct opp *devfreq_recommended_opp(struct device *dev, 163 unsigned long *freq); 164 extern int devfreq_register_opp_notifier(struct device *dev, 165 struct devfreq *devfreq); 166 extern int devfreq_unregister_opp_notifier(struct device *dev, 167 struct devfreq *devfreq); 168 169 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE 170 extern const struct devfreq_governor devfreq_powersave; 171 #endif 172 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE 173 extern const struct devfreq_governor devfreq_performance; 174 #endif 175 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE 176 extern const struct devfreq_governor devfreq_userspace; 177 #endif 178 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND 179 extern const struct devfreq_governor devfreq_simple_ondemand; 180 /** 181 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq 182 * and devfreq_add_device 183 * @ upthreshold If the load is over this value, the frequency jumps. 184 * Specify 0 to use the default. Valid value = 0 to 100. 185 * @ downdifferential If the load is under upthreshold - downdifferential, 186 * the governor may consider slowing the frequency down. 187 * Specify 0 to use the default. Valid value = 0 to 100. 188 * downdifferential < upthreshold must hold. 189 * 190 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor, 191 * the governor uses the default values. 192 */ 193 struct devfreq_simple_ondemand_data { 194 unsigned int upthreshold; 195 unsigned int downdifferential; 196 }; 197 #endif 198 199 #else /* !CONFIG_PM_DEVFREQ */ 200 static struct devfreq *devfreq_add_device(struct device *dev, 201 struct devfreq_dev_profile *profile, 202 struct devfreq_governor *governor, 203 void *data); 204 { 205 return NULL; 206 } 207 208 static int devfreq_remove_device(struct devfreq *devfreq); 209 { 210 return 0; 211 } 212 213 static struct opp *devfreq_recommended_opp(struct device *dev, 214 unsigned long *freq) 215 { 216 return -EINVAL; 217 } 218 219 static int devfreq_register_opp_notifier(struct device *dev, 220 struct devfreq *devfreq) 221 { 222 return -EINVAL; 223 } 224 225 static int devfreq_unregister_opp_notifier(struct device *dev, 226 struct devfreq *devfreq) 227 { 228 return -EINVAL; 229 } 230 231 #define devfreq_powersave NULL 232 #define devfreq_performance NULL 233 #define devfreq_userspace NULL 234 #define devfreq_simple_ondemand NULL 235 236 #endif /* CONFIG_PM_DEVFREQ */ 237 238 #endif /* __LINUX_DEVFREQ_H__ */ 239