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 static int get_trip_level(struct thermal_zone_device *tz) 19 { 20 const struct thermal_trip *trip, *level_trip = NULL; 21 int trip_level; 22 23 for_each_trip(tz, trip) { 24 if (trip->temperature >= tz->temperature) 25 break; 26 27 level_trip = trip; 28 } 29 30 /* Bail out if the temperature is not greater than any trips. */ 31 if (!level_trip) 32 return 0; 33 34 trip_level = thermal_zone_trip_id(tz, level_trip); 35 36 trace_thermal_zone_trip(tz, trip_level, level_trip->type); 37 38 return trip_level; 39 } 40 41 static long get_target_state(struct thermal_zone_device *tz, 42 struct thermal_cooling_device *cdev, int percentage, int level) 43 { 44 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips); 45 } 46 47 /** 48 * fair_share_throttle - throttles devices associated with the given zone 49 * @tz: thermal_zone_device 50 * @trip: trip point 51 * 52 * Throttling Logic: This uses three parameters to calculate the new 53 * throttle state of the cooling devices associated with the given zone. 54 * 55 * Parameters used for Throttling: 56 * P1. max_state: Maximum throttle state exposed by the cooling device. 57 * P2. percentage[i]/100: 58 * How 'effective' the 'i'th device is, in cooling the given zone. 59 * P3. cur_trip_level/max_no_of_trips: 60 * This describes the extent to which the devices should be throttled. 61 * We do not want to throttle too much when we trip a lower temperature, 62 * whereas the throttling is at full swing if we trip critical levels. 63 * (Heavily assumes the trip points are in ascending order) 64 * new_state of cooling device = P3 * P2 * P1 65 */ 66 static int fair_share_throttle(struct thermal_zone_device *tz, 67 const struct thermal_trip *trip) 68 { 69 struct thermal_instance *instance; 70 int total_weight = 0; 71 int total_instance = 0; 72 int cur_trip_level = get_trip_level(tz); 73 74 lockdep_assert_held(&tz->lock); 75 76 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 77 if (instance->trip != trip) 78 continue; 79 80 total_weight += instance->weight; 81 total_instance++; 82 } 83 84 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 85 int percentage; 86 struct thermal_cooling_device *cdev = instance->cdev; 87 88 if (instance->trip != trip) 89 continue; 90 91 if (!total_weight) 92 percentage = 100 / total_instance; 93 else 94 percentage = (instance->weight * 100) / total_weight; 95 96 instance->target = get_target_state(tz, cdev, percentage, 97 cur_trip_level); 98 99 mutex_lock(&cdev->lock); 100 __thermal_cdev_update(cdev); 101 mutex_unlock(&cdev->lock); 102 } 103 104 return 0; 105 } 106 107 static struct thermal_governor thermal_gov_fair_share = { 108 .name = "fair_share", 109 .throttle = fair_share_throttle, 110 }; 111 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); 112