1/* 2 * step_wise.c - A step-by-step Thermal throttling governor 3 * 4 * Copyright (C) 2012 Intel Corp 5 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com> 6 * 7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; version 2 of the License. 12 * 13 * This program is distributed in the hope that it will be useful, but 14 * WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License along 19 * with this program; if not, write to the Free Software Foundation, Inc., 20 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. 21 * 22 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 23 */ 24 25#include <linux/thermal.h> 26#include <trace/events/thermal.h> 27 28#include "thermal_core.h" 29 30/* 31 * If the temperature is higher than a trip point, 32 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling 33 * state for this trip point 34 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling 35 * state for this trip point 36 * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit 37 * for this trip point 38 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit 39 * for this trip point 40 * If the temperature is lower than a trip point, 41 * a. if the trend is THERMAL_TREND_RAISING, do nothing 42 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling 43 * state for this trip point, if the cooling state already 44 * equals lower limit, deactivate the thermal instance 45 * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing 46 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit, 47 * if the cooling state already equals lower limit, 48 * deactivate the thermal instance 49 */ 50static unsigned long get_target_state(struct thermal_instance *instance, 51 enum thermal_trend trend, bool throttle) 52{ 53 struct thermal_cooling_device *cdev = instance->cdev; 54 unsigned long cur_state; 55 unsigned long next_target; 56 57 /* 58 * We keep this instance the way it is by default. 59 * Otherwise, we use the current state of the 60 * cdev in use to determine the next_target. 61 */ 62 cdev->ops->get_cur_state(cdev, &cur_state); 63 next_target = instance->target; 64 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state); 65 66 if (!instance->initialized) { 67 if (throttle) { 68 next_target = (cur_state + 1) >= instance->upper ? 69 instance->upper : 70 ((cur_state + 1) < instance->lower ? 71 instance->lower : (cur_state + 1)); 72 } else { 73 next_target = THERMAL_NO_TARGET; 74 } 75 76 return next_target; 77 } 78 79 switch (trend) { 80 case THERMAL_TREND_RAISING: 81 if (throttle) { 82 next_target = cur_state < instance->upper ? 83 (cur_state + 1) : instance->upper; 84 if (next_target < instance->lower) 85 next_target = instance->lower; 86 } 87 break; 88 case THERMAL_TREND_RAISE_FULL: 89 if (throttle) 90 next_target = instance->upper; 91 break; 92 case THERMAL_TREND_DROPPING: 93 if (cur_state <= instance->lower) { 94 if (!throttle) 95 next_target = THERMAL_NO_TARGET; 96 } else { 97 next_target = cur_state - 1; 98 if (next_target > instance->upper) 99 next_target = instance->upper; 100 } 101 break; 102 case THERMAL_TREND_DROP_FULL: 103 if (cur_state == instance->lower) { 104 if (!throttle) 105 next_target = THERMAL_NO_TARGET; 106 } else 107 next_target = instance->lower; 108 break; 109 default: 110 break; 111 } 112 113 return next_target; 114} 115 116static void update_passive_instance(struct thermal_zone_device *tz, 117 enum thermal_trip_type type, int value) 118{ 119 /* 120 * If value is +1, activate a passive instance. 121 * If value is -1, deactivate a passive instance. 122 */ 123 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE) 124 tz->passive += value; 125} 126 127static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip) 128{ 129 long trip_temp; 130 enum thermal_trip_type trip_type; 131 enum thermal_trend trend; 132 struct thermal_instance *instance; 133 bool throttle = false; 134 int old_target; 135 136 if (trip == THERMAL_TRIPS_NONE) { 137 trip_temp = tz->forced_passive; 138 trip_type = THERMAL_TRIPS_NONE; 139 } else { 140 tz->ops->get_trip_temp(tz, trip, &trip_temp); 141 tz->ops->get_trip_type(tz, trip, &trip_type); 142 } 143 144 trend = get_tz_trend(tz, trip); 145 146 if (tz->temperature >= trip_temp) { 147 throttle = true; 148 trace_thermal_zone_trip(tz, trip, trip_type); 149 } 150 151 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n", 152 trip, trip_type, trip_temp, trend, throttle); 153 154 mutex_lock(&tz->lock); 155 156 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 157 if (instance->trip != trip) 158 continue; 159 160 old_target = instance->target; 161 instance->target = get_target_state(instance, trend, throttle); 162 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", 163 old_target, (int)instance->target); 164 165 if (instance->initialized && old_target == instance->target) 166 continue; 167 168 /* Activate a passive thermal instance */ 169 if (old_target == THERMAL_NO_TARGET && 170 instance->target != THERMAL_NO_TARGET) 171 update_passive_instance(tz, trip_type, 1); 172 /* Deactivate a passive thermal instance */ 173 else if (old_target != THERMAL_NO_TARGET && 174 instance->target == THERMAL_NO_TARGET) 175 update_passive_instance(tz, trip_type, -1); 176 177 instance->initialized = true; 178 instance->cdev->updated = false; /* cdev needs update */ 179 } 180 181 mutex_unlock(&tz->lock); 182} 183 184/** 185 * step_wise_throttle - throttles devices associated with the given zone 186 * @tz - thermal_zone_device 187 * @trip - the trip point 188 * @trip_type - type of the trip point 189 * 190 * Throttling Logic: This uses the trend of the thermal zone to throttle. 191 * If the thermal zone is 'heating up' this throttles all the cooling 192 * devices associated with the zone and its particular trip point, by one 193 * step. If the zone is 'cooling down' it brings back the performance of 194 * the devices by one step. 195 */ 196static int step_wise_throttle(struct thermal_zone_device *tz, int trip) 197{ 198 struct thermal_instance *instance; 199 200 thermal_zone_trip_update(tz, trip); 201 202 if (tz->forced_passive) 203 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE); 204 205 mutex_lock(&tz->lock); 206 207 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 208 thermal_cdev_update(instance->cdev); 209 210 mutex_unlock(&tz->lock); 211 212 return 0; 213} 214 215static struct thermal_governor thermal_gov_step_wise = { 216 .name = "step_wise", 217 .throttle = step_wise_throttle, 218}; 219 220int thermal_gov_step_wise_register(void) 221{ 222 return thermal_register_governor(&thermal_gov_step_wise); 223} 224 225void thermal_gov_step_wise_unregister(void) 226{ 227 thermal_unregister_governor(&thermal_gov_step_wise); 228} 229