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 /* 59 * If 'throttle' is false, no mitigation is necessary, so 60 * request the lower state for this instance. 61 */ 62 return instance->lower; 63 } 64 65 return instance->target; 66 } 67 68 static void thermal_zone_trip_update(struct thermal_zone_device *tz, 69 const struct thermal_trip_desc *td, 70 int trip_threshold) 71 { 72 const struct thermal_trip *trip = &td->trip; 73 enum thermal_trend trend = get_tz_trend(tz, trip); 74 int trip_id = thermal_zone_trip_id(tz, trip); 75 struct thermal_instance *instance; 76 bool throttle = false; 77 78 if (tz->temperature >= trip_threshold) { 79 throttle = true; 80 trace_thermal_zone_trip(tz, trip_id, trip->type); 81 } 82 83 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 84 trip_id, trip->type, trip_threshold, trend, throttle); 85 86 list_for_each_entry(instance, &td->thermal_instances, trip_node) { 87 int old_target; 88 89 old_target = instance->target; 90 instance->target = get_target_state(instance, trend, throttle); 91 92 dev_dbg(&instance->cdev->device, "old_target=%d, target=%ld\n", 93 old_target, instance->target); 94 95 if (instance->initialized && old_target == instance->target) 96 continue; 97 98 instance->initialized = true; 99 100 scoped_guard(cooling_dev, instance->cdev) { 101 instance->cdev->updated = false; /* cdev needs update */ 102 } 103 } 104 } 105 106 static void step_wise_manage(struct thermal_zone_device *tz) 107 { 108 const struct thermal_trip_desc *td; 109 struct thermal_instance *instance; 110 111 lockdep_assert_held(&tz->lock); 112 113 /* 114 * Throttling Logic: Use the trend of the thermal zone to throttle. 115 * If the thermal zone is 'heating up', throttle all of the cooling 116 * devices associated with each trip point by one step. If the zone 117 * is 'cooling down', it brings back the performance of the devices 118 * by one step. 119 */ 120 for_each_trip_desc(tz, td) { 121 const struct thermal_trip *trip = &td->trip; 122 123 if (trip->temperature == THERMAL_TEMP_INVALID || 124 trip->type == THERMAL_TRIP_CRITICAL || 125 trip->type == THERMAL_TRIP_HOT) 126 continue; 127 128 thermal_zone_trip_update(tz, td, td->threshold); 129 } 130 131 for_each_trip_desc(tz, td) { 132 list_for_each_entry(instance, &td->thermal_instances, trip_node) 133 thermal_cdev_update(instance->cdev); 134 } 135 } 136 137 static struct thermal_governor thermal_gov_step_wise = { 138 .name = "step_wise", 139 .manage = step_wise_manage, 140 }; 141 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 142