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 "thermal_trace.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 struct thermal_trip trip; 25 int count; 26 27 for (count = 0; count < tz->num_trips; count++) { 28 __thermal_zone_get_trip(tz, count, &trip); 29 if (tz->temperature < trip.temperature) 30 break; 31 } 32 33 /* 34 * count > 0 only if temperature is greater than first trip 35 * point, in which case, trip_point = count - 1 36 */ 37 if (count > 0) 38 trace_thermal_zone_trip(tz, count - 1, trip.type); 39 40 return count; 41 } 42 43 static long get_target_state(struct thermal_zone_device *tz, 44 struct thermal_cooling_device *cdev, int percentage, int level) 45 { 46 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips); 47 } 48 49 /** 50 * fair_share_throttle - throttles devices associated with the given zone 51 * @tz: thermal_zone_device 52 * @trip: trip point index 53 * 54 * Throttling Logic: This uses three parameters to calculate the new 55 * throttle state of the cooling devices associated with the given zone. 56 * 57 * Parameters used for Throttling: 58 * P1. max_state: Maximum throttle state exposed by the cooling device. 59 * P2. percentage[i]/100: 60 * How 'effective' the 'i'th device is, in cooling the given zone. 61 * P3. cur_trip_level/max_no_of_trips: 62 * This describes the extent to which the devices should be throttled. 63 * We do not want to throttle too much when we trip a lower temperature, 64 * whereas the throttling is at full swing if we trip critical levels. 65 * (Heavily assumes the trip points are in ascending order) 66 * new_state of cooling device = P3 * P2 * P1 67 */ 68 static int fair_share_throttle(struct thermal_zone_device *tz, int trip) 69 { 70 struct thermal_instance *instance; 71 int total_weight = 0; 72 int total_instance = 0; 73 int cur_trip_level = get_trip_level(tz); 74 75 lockdep_assert_held(&tz->lock); 76 77 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 78 if (instance->trip != trip) 79 continue; 80 81 total_weight += instance->weight; 82 total_instance++; 83 } 84 85 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 86 int percentage; 87 struct thermal_cooling_device *cdev = instance->cdev; 88 89 if (instance->trip != trip) 90 continue; 91 92 if (!total_weight) 93 percentage = 100 / total_instance; 94 else 95 percentage = (instance->weight * 100) / total_weight; 96 97 instance->target = get_target_state(tz, cdev, percentage, 98 cur_trip_level); 99 100 mutex_lock(&cdev->lock); 101 __thermal_cdev_update(cdev); 102 mutex_unlock(&cdev->lock); 103 } 104 105 return 0; 106 } 107 108 static struct thermal_governor thermal_gov_fair_share = { 109 .name = "fair_share", 110 .throttle = fair_share_throttle, 111 }; 112 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); 113