1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * step_wise.c - A step-by-step Thermal throttling governor 4 * 5 * Copyright (C) 2012 Intel Corp 6 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com> 7 * 8 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 9 * 10 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 11 */ 12 13 #include <linux/thermal.h> 14 #include <trace/events/thermal.h> 15 16 #include "thermal_core.h" 17 18 /* 19 * If the temperature is higher than a trip point, 20 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling 21 * state for this trip point 22 * b. if the trend is THERMAL_TREND_DROPPING, do nothing 23 * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit 24 * for this trip point 25 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit 26 * for this trip point 27 * If the temperature is lower than a trip point, 28 * a. if the trend is THERMAL_TREND_RAISING, do nothing 29 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling 30 * state for this trip point, if the cooling state already 31 * equals lower limit, deactivate the thermal instance 32 * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing 33 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit, 34 * if the cooling state already equals lower limit, 35 * deactivate the thermal instance 36 */ 37 static unsigned long get_target_state(struct thermal_instance *instance, 38 enum thermal_trend trend, bool throttle) 39 { 40 struct thermal_cooling_device *cdev = instance->cdev; 41 unsigned long cur_state; 42 unsigned long next_target; 43 44 /* 45 * We keep this instance the way it is by default. 46 * Otherwise, we use the current state of the 47 * cdev in use to determine the next_target. 48 */ 49 cdev->ops->get_cur_state(cdev, &cur_state); 50 next_target = instance->target; 51 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state); 52 53 if (!instance->initialized) { 54 if (throttle) { 55 next_target = (cur_state + 1) >= instance->upper ? 56 instance->upper : 57 ((cur_state + 1) < instance->lower ? 58 instance->lower : (cur_state + 1)); 59 } else { 60 next_target = THERMAL_NO_TARGET; 61 } 62 63 return next_target; 64 } 65 66 switch (trend) { 67 case THERMAL_TREND_RAISING: 68 if (throttle) { 69 next_target = cur_state < instance->upper ? 70 (cur_state + 1) : instance->upper; 71 if (next_target < instance->lower) 72 next_target = instance->lower; 73 } 74 break; 75 case THERMAL_TREND_RAISE_FULL: 76 if (throttle) 77 next_target = instance->upper; 78 break; 79 case THERMAL_TREND_DROPPING: 80 if (cur_state <= instance->lower) { 81 if (!throttle) 82 next_target = THERMAL_NO_TARGET; 83 } else { 84 if (!throttle) { 85 next_target = cur_state - 1; 86 if (next_target > instance->upper) 87 next_target = instance->upper; 88 } 89 } 90 break; 91 case THERMAL_TREND_DROP_FULL: 92 if (cur_state == instance->lower) { 93 if (!throttle) 94 next_target = THERMAL_NO_TARGET; 95 } else 96 next_target = instance->lower; 97 break; 98 default: 99 break; 100 } 101 102 return next_target; 103 } 104 105 static void update_passive_instance(struct thermal_zone_device *tz, 106 enum thermal_trip_type type, int value) 107 { 108 /* 109 * If value is +1, activate a passive instance. 110 * If value is -1, deactivate a passive instance. 111 */ 112 if (type == THERMAL_TRIP_PASSIVE) 113 tz->passive += value; 114 } 115 116 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip) 117 { 118 int trip_temp; 119 enum thermal_trip_type trip_type; 120 enum thermal_trend trend; 121 struct thermal_instance *instance; 122 bool throttle = false; 123 int old_target; 124 125 tz->ops->get_trip_temp(tz, trip, &trip_temp); 126 tz->ops->get_trip_type(tz, trip, &trip_type); 127 128 trend = get_tz_trend(tz, trip); 129 130 if (tz->temperature >= trip_temp) { 131 throttle = true; 132 trace_thermal_zone_trip(tz, trip, trip_type); 133 } 134 135 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 136 trip, trip_type, trip_temp, trend, throttle); 137 138 mutex_lock(&tz->lock); 139 140 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 141 if (instance->trip != trip) 142 continue; 143 144 old_target = instance->target; 145 instance->target = get_target_state(instance, trend, throttle); 146 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", 147 old_target, (int)instance->target); 148 149 if (instance->initialized && old_target == instance->target) 150 continue; 151 152 /* Activate a passive thermal instance */ 153 if (old_target == THERMAL_NO_TARGET && 154 instance->target != THERMAL_NO_TARGET) 155 update_passive_instance(tz, trip_type, 1); 156 /* Deactivate a passive thermal instance */ 157 else if (old_target != THERMAL_NO_TARGET && 158 instance->target == THERMAL_NO_TARGET) 159 update_passive_instance(tz, trip_type, -1); 160 161 instance->initialized = true; 162 mutex_lock(&instance->cdev->lock); 163 instance->cdev->updated = false; /* cdev needs update */ 164 mutex_unlock(&instance->cdev->lock); 165 } 166 167 mutex_unlock(&tz->lock); 168 } 169 170 /** 171 * step_wise_throttle - throttles devices associated with the given zone 172 * @tz: thermal_zone_device 173 * @trip: trip point index 174 * 175 * Throttling Logic: This uses the trend of the thermal zone to throttle. 176 * If the thermal zone is 'heating up' this throttles all the cooling 177 * devices associated with the zone and its particular trip point, by one 178 * step. If the zone is 'cooling down' it brings back the performance of 179 * the devices by one step. 180 */ 181 static int step_wise_throttle(struct thermal_zone_device *tz, int trip) 182 { 183 struct thermal_instance *instance; 184 185 thermal_zone_trip_update(tz, trip); 186 187 mutex_lock(&tz->lock); 188 189 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 190 thermal_cdev_update(instance->cdev); 191 192 mutex_unlock(&tz->lock); 193 194 return 0; 195 } 196 197 static struct thermal_governor thermal_gov_step_wise = { 198 .name = "step_wise", 199 .throttle = step_wise_throttle, 200 }; 201 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 202