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 { 67 int trip_id = thermal_zone_trip_id(tz, trip); 68 enum thermal_trend trend; 69 struct thermal_instance *instance; 70 bool throttle = false; 71 int old_target; 72 73 trend = get_tz_trend(tz, trip); 74 75 if (tz->temperature >= trip->temperature) { 76 throttle = true; 77 trace_thermal_zone_trip(tz, trip_id, trip->type); 78 } 79 80 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n", 81 trip_id, trip->type, trip->temperature, trend, throttle); 82 83 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 84 if (instance->trip != trip) 85 continue; 86 87 old_target = instance->target; 88 instance->target = get_target_state(instance, trend, throttle); 89 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", 90 old_target, (int)instance->target); 91 92 if (instance->initialized && old_target == instance->target) 93 continue; 94 95 if (trip->type == THERMAL_TRIP_PASSIVE) { 96 /* If needed, update the status of passive polling. */ 97 if (old_target == THERMAL_NO_TARGET && 98 instance->target != THERMAL_NO_TARGET) 99 tz->passive++; 100 else if (old_target != THERMAL_NO_TARGET && 101 instance->target == THERMAL_NO_TARGET) 102 tz->passive--; 103 } 104 105 instance->initialized = true; 106 mutex_lock(&instance->cdev->lock); 107 instance->cdev->updated = false; /* cdev needs update */ 108 mutex_unlock(&instance->cdev->lock); 109 } 110 } 111 112 /** 113 * step_wise_throttle - throttles devices associated with the given zone 114 * @tz: thermal_zone_device 115 * @trip: trip point 116 * 117 * Throttling Logic: This uses the trend of the thermal zone to throttle. 118 * If the thermal zone is 'heating up' this throttles all the cooling 119 * devices associated with the zone and its particular trip point, by one 120 * step. If the zone is 'cooling down' it brings back the performance of 121 * the devices by one step. 122 */ 123 static int step_wise_throttle(struct thermal_zone_device *tz, 124 const struct thermal_trip *trip) 125 { 126 struct thermal_instance *instance; 127 128 lockdep_assert_held(&tz->lock); 129 130 thermal_zone_trip_update(tz, trip); 131 132 list_for_each_entry(instance, &tz->thermal_instances, tz_node) 133 thermal_cdev_update(instance->cdev); 134 135 return 0; 136 } 137 138 static struct thermal_governor thermal_gov_step_wise = { 139 .name = "step_wise", 140 .throttle = step_wise_throttle, 141 }; 142 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); 143