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 36 /* 37 * We keep this instance the way it is by default. 38 * Otherwise, we use the current state of the 39 * cdev in use to determine the next_target. 40 */ 41 cdev->ops->get_cur_state(cdev, &cur_state); 42 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state); 43 44 if (!instance->initialized) { 45 if (throttle) 46 return clamp(cur_state + 1, instance->lower, instance->upper); 47 48 return THERMAL_NO_TARGET; 49 } 50 51 if (throttle) { 52 if (trend == THERMAL_TREND_RAISING) 53 return clamp(cur_state + 1, instance->lower, instance->upper); 54 } else if (trend == THERMAL_TREND_DROPPING) { 55 if (cur_state <= instance->lower) 56 return THERMAL_NO_TARGET; 57 58 return clamp(cur_state - 1, instance->lower, instance->upper); 59 } 60 61 return instance->target; 62 } 63 64 static void thermal_zone_trip_update(struct thermal_zone_device *tz, 65 const struct thermal_trip *trip, 66 int trip_threshold) 67 { 68 enum thermal_trend trend = get_tz_trend(tz, trip); 69 int trip_id = thermal_zone_trip_id(tz, trip); 70 struct thermal_instance *instance; 71 bool throttle = false; 72 73 if (tz->temperature >= trip_threshold) { 74 throttle = true; 75 trace_thermal_zone_trip(tz, trip_id, trip->type); 76 } 77 78 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 79 trip_id, trip->type, trip_threshold, trend, throttle); 80 81 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 82 int old_target; 83 84 if (instance->trip != trip) 85 continue; 86 87 old_target = instance->target; 88 instance->target = get_target_state(instance, trend, throttle); 89 90 dev_dbg(&instance->cdev->device, "old_target=%d, target=%ld\n", 91 old_target, instance->target); 92 93 if (instance->initialized && old_target == instance->target) 94 continue; 95 96 if (trip->type == THERMAL_TRIP_PASSIVE) { 97 /* 98 * If the target state for this thermal instance 99 * changes from THERMAL_NO_TARGET to something else, 100 * ensure that the zone temperature will be updated 101 * (assuming enabled passive cooling) until it becomes 102 * THERMAL_NO_TARGET again, or the cooling device may 103 * not be reset to its initial state. 104 */ 105 if (old_target == THERMAL_NO_TARGET && 106 instance->target != THERMAL_NO_TARGET) 107 tz->passive++; 108 else if (old_target != THERMAL_NO_TARGET && 109 instance->target == THERMAL_NO_TARGET) 110 tz->passive--; 111 } 112 113 instance->initialized = true; 114 115 mutex_lock(&instance->cdev->lock); 116 instance->cdev->updated = false; /* cdev needs update */ 117 mutex_unlock(&instance->cdev->lock); 118 } 119 } 120 121 static void step_wise_manage(struct thermal_zone_device *tz) 122 { 123 const struct thermal_trip_desc *td; 124 struct thermal_instance *instance; 125 126 lockdep_assert_held(&tz->lock); 127 128 /* 129 * Throttling Logic: Use the trend of the thermal zone to throttle. 130 * If the thermal zone is 'heating up', throttle all of the cooling 131 * devices associated with each trip point by one step. If the zone 132 * is 'cooling down', it brings back the performance of the devices 133 * by one step. 134 */ 135 for_each_trip_desc(tz, td) { 136 const struct thermal_trip *trip = &td->trip; 137 138 if (trip->temperature == THERMAL_TEMP_INVALID || 139 trip->type == THERMAL_TRIP_CRITICAL || 140 trip->type == THERMAL_TRIP_HOT) 141 continue; 142 143 thermal_zone_trip_update(tz, trip, td->threshold); 144 } 145 146 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 147 thermal_cdev_update(instance->cdev); 148 } 149 150 static struct thermal_governor thermal_gov_step_wise = { 151 .name = "step_wise", 152 .manage = step_wise_manage, 153 }; 154 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 155