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 <linux/minmax.h> 15 #include "thermal_trace.h" 16 17 #include "thermal_core.h" 18 19 /* 20 * If the temperature is higher than a trip point, 21 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling 22 * state for this trip point 23 * b. if the trend is THERMAL_TREND_DROPPING, do nothing 24 * If the temperature is lower than a trip point, 25 * a. if the trend is THERMAL_TREND_RAISING, do nothing 26 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling 27 * state for this trip point, if the cooling state already 28 * equals lower limit, deactivate the thermal instance 29 */ 30 static unsigned long get_target_state(struct thermal_instance *instance, 31 enum thermal_trend trend, bool throttle) 32 { 33 struct thermal_cooling_device *cdev = instance->cdev; 34 unsigned long cur_state; 35 unsigned long next_target; 36 37 /* 38 * We keep this instance the way it is by default. 39 * Otherwise, we use the current state of the 40 * cdev in use to determine the next_target. 41 */ 42 cdev->ops->get_cur_state(cdev, &cur_state); 43 next_target = instance->target; 44 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state); 45 46 if (!instance->initialized) { 47 if (throttle) { 48 next_target = clamp((cur_state + 1), instance->lower, instance->upper); 49 } else { 50 next_target = THERMAL_NO_TARGET; 51 } 52 53 return next_target; 54 } 55 56 if (throttle) { 57 if (trend == THERMAL_TREND_RAISING) 58 next_target = clamp((cur_state + 1), instance->lower, instance->upper); 59 } else { 60 if (trend == THERMAL_TREND_DROPPING) { 61 if (cur_state <= instance->lower) 62 next_target = THERMAL_NO_TARGET; 63 else 64 next_target = clamp((cur_state - 1), instance->lower, instance->upper); 65 } 66 } 67 68 return next_target; 69 } 70 71 static void update_passive_instance(struct thermal_zone_device *tz, 72 enum thermal_trip_type type, int value) 73 { 74 /* 75 * If value is +1, activate a passive instance. 76 * If value is -1, deactivate a passive instance. 77 */ 78 if (type == THERMAL_TRIP_PASSIVE) 79 tz->passive += value; 80 } 81 82 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip_id) 83 { 84 enum thermal_trend trend; 85 struct thermal_instance *instance; 86 struct thermal_trip trip; 87 bool throttle = false; 88 int old_target; 89 90 __thermal_zone_get_trip(tz, trip_id, &trip); 91 92 trend = get_tz_trend(tz, trip_id); 93 94 if (tz->temperature >= trip.temperature) { 95 throttle = true; 96 trace_thermal_zone_trip(tz, trip_id, trip.type); 97 } 98 99 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 100 trip_id, trip.type, trip.temperature, trend, throttle); 101 102 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 103 if (instance->trip != trip_id) 104 continue; 105 106 old_target = instance->target; 107 instance->target = get_target_state(instance, trend, throttle); 108 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", 109 old_target, (int)instance->target); 110 111 if (instance->initialized && old_target == instance->target) 112 continue; 113 114 /* Activate a passive thermal instance */ 115 if (old_target == THERMAL_NO_TARGET && 116 instance->target != THERMAL_NO_TARGET) 117 update_passive_instance(tz, trip.type, 1); 118 /* Deactivate a passive thermal instance */ 119 else if (old_target != THERMAL_NO_TARGET && 120 instance->target == THERMAL_NO_TARGET) 121 update_passive_instance(tz, trip.type, -1); 122 123 instance->initialized = true; 124 mutex_lock(&instance->cdev->lock); 125 instance->cdev->updated = false; /* cdev needs update */ 126 mutex_unlock(&instance->cdev->lock); 127 } 128 } 129 130 /** 131 * step_wise_throttle - throttles devices associated with the given zone 132 * @tz: thermal_zone_device 133 * @trip: trip point index 134 * 135 * Throttling Logic: This uses the trend of the thermal zone to throttle. 136 * If the thermal zone is 'heating up' this throttles all the cooling 137 * devices associated with the zone and its particular trip point, by one 138 * step. If the zone is 'cooling down' it brings back the performance of 139 * the devices by one step. 140 */ 141 static int step_wise_throttle(struct thermal_zone_device *tz, int trip) 142 { 143 struct thermal_instance *instance; 144 145 lockdep_assert_held(&tz->lock); 146 147 thermal_zone_trip_update(tz, trip); 148 149 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 150 thermal_cdev_update(instance->cdev); 151 152 return 0; 153 } 154 155 static struct thermal_governor thermal_gov_step_wise = { 156 .name = "step_wise", 157 .throttle = step_wise_throttle, 158 }; 159 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 160