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 thermal_zone_trip_update(struct thermal_zone_device *tz, 72 const struct thermal_trip *trip) 73 { 74 int trip_id = thermal_zone_trip_id(tz, trip); 75 enum thermal_trend trend; 76 struct thermal_instance *instance; 77 bool throttle = false; 78 int old_target; 79 80 trend = get_tz_trend(tz, trip); 81 82 if (tz->temperature >= trip->temperature) { 83 throttle = true; 84 trace_thermal_zone_trip(tz, trip_id, trip->type); 85 } 86 87 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 88 trip_id, trip->type, trip->temperature, trend, throttle); 89 90 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 91 if (instance->trip != trip) 92 continue; 93 94 old_target = instance->target; 95 instance->target = get_target_state(instance, trend, throttle); 96 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", 97 old_target, (int)instance->target); 98 99 if (instance->initialized && old_target == instance->target) 100 continue; 101 102 if (old_target == THERMAL_NO_TARGET && 103 instance->target != THERMAL_NO_TARGET) { 104 /* Activate a passive thermal instance */ 105 if (trip->type == THERMAL_TRIP_PASSIVE) 106 tz->passive++; 107 } else if (old_target != THERMAL_NO_TARGET && 108 instance->target == THERMAL_NO_TARGET) { 109 /* Deactivate a passive thermal instance */ 110 if (trip->type == THERMAL_TRIP_PASSIVE) 111 tz->passive--; 112 } 113 114 instance->initialized = true; 115 mutex_lock(&instance->cdev->lock); 116 instance->cdev->updated = false; /* cdev needs update */ 117 mutex_unlock(&instance->cdev->lock); 118 } 119 } 120 121 /** 122 * step_wise_throttle - throttles devices associated with the given zone 123 * @tz: thermal_zone_device 124 * @trip: trip point 125 * 126 * Throttling Logic: This uses the trend of the thermal zone to throttle. 127 * If the thermal zone is 'heating up' this throttles all the cooling 128 * devices associated with the zone and its particular trip point, by one 129 * step. If the zone is 'cooling down' it brings back the performance of 130 * the devices by one step. 131 */ 132 static int step_wise_throttle(struct thermal_zone_device *tz, 133 const struct thermal_trip *trip) 134 { 135 struct thermal_instance *instance; 136 137 lockdep_assert_held(&tz->lock); 138 139 thermal_zone_trip_update(tz, trip); 140 141 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 142 thermal_cdev_update(instance->cdev); 143 144 return 0; 145 } 146 147 static struct thermal_governor thermal_gov_step_wise = { 148 .name = "step_wise", 149 .throttle = step_wise_throttle, 150 }; 151 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 152