1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * fair_share.c - A simple weight based Thermal 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 <trace/events/thermal.h> 15 16 #include "thermal_core.h" 17 18 /** 19 * get_trip_level: - obtains the current trip level for a zone 20 * @tz: thermal zone device 21 */ 22 static int get_trip_level(struct thermal_zone_device *tz) 23 { 24 int count = 0; 25 int trip_temp; 26 enum thermal_trip_type trip_type; 27 28 if (tz->trips == 0 || !tz->ops->get_trip_temp) 29 return 0; 30 31 for (count = 0; count < tz->trips; count++) { 32 tz->ops->get_trip_temp(tz, count, &trip_temp); 33 if (tz->temperature < trip_temp) 34 break; 35 } 36 37 /* 38 * count > 0 only if temperature is greater than first trip 39 * point, in which case, trip_point = count - 1 40 */ 41 if (count > 0) { 42 tz->ops->get_trip_type(tz, count - 1, &trip_type); 43 trace_thermal_zone_trip(tz, count - 1, trip_type); 44 } 45 46 return count; 47 } 48 49 static long get_target_state(struct thermal_zone_device *tz, 50 struct thermal_cooling_device *cdev, int percentage, int level) 51 { 52 unsigned long max_state; 53 54 cdev->ops->get_max_state(cdev, &max_state); 55 56 return (long)(percentage * level * max_state) / (100 * tz->trips); 57 } 58 59 /** 60 * fair_share_throttle - throttles devices associated with the given zone 61 * @tz: thermal_zone_device 62 * @trip: trip point index 63 * 64 * Throttling Logic: This uses three parameters to calculate the new 65 * throttle state of the cooling devices associated with the given zone. 66 * 67 * Parameters used for Throttling: 68 * P1. max_state: Maximum throttle state exposed by the cooling device. 69 * P2. percentage[i]/100: 70 * How 'effective' the 'i'th device is, in cooling the given zone. 71 * P3. cur_trip_level/max_no_of_trips: 72 * This describes the extent to which the devices should be throttled. 73 * We do not want to throttle too much when we trip a lower temperature, 74 * whereas the throttling is at full swing if we trip critical levels. 75 * (Heavily assumes the trip points are in ascending order) 76 * new_state of cooling device = P3 * P2 * P1 77 */ 78 static int fair_share_throttle(struct thermal_zone_device *tz, int trip) 79 { 80 struct thermal_instance *instance; 81 int total_weight = 0; 82 int total_instance = 0; 83 int cur_trip_level = get_trip_level(tz); 84 85 mutex_lock(&tz->lock); 86 87 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 88 if (instance->trip != trip) 89 continue; 90 91 total_weight += instance->weight; 92 total_instance++; 93 } 94 95 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 96 int percentage; 97 struct thermal_cooling_device *cdev = instance->cdev; 98 99 if (instance->trip != trip) 100 continue; 101 102 if (!total_weight) 103 percentage = 100 / total_instance; 104 else 105 percentage = (instance->weight * 100) / total_weight; 106 107 instance->target = get_target_state(tz, cdev, percentage, 108 cur_trip_level); 109 110 mutex_lock(&cdev->lock); 111 __thermal_cdev_update(cdev); 112 mutex_unlock(&cdev->lock); 113 } 114 115 mutex_unlock(&tz->lock); 116 return 0; 117 } 118 119 static struct thermal_governor thermal_gov_fair_share = { 120 .name = "fair_share", 121 .throttle = fair_share_throttle, 122 }; 123 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); 124