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 *level_trip = NULL; 21 const struct thermal_trip_desc *td; 22 int trip_level = -1; 23 24 for_each_trip_desc(tz, td) { 25 const struct thermal_trip *trip = &td->trip; 26 27 if (trip->temperature >= tz->temperature) 28 continue; 29 30 trip_level++; 31 32 if (!level_trip || trip->temperature > level_trip->temperature) 33 level_trip = trip; 34 } 35 36 /* Bail out if the temperature is not greater than any trips. */ 37 if (trip_level < 0) 38 return 0; 39 40 trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, level_trip), 41 level_trip->type); 42 43 return trip_level; 44 } 45 46 static long get_target_state(struct thermal_zone_device *tz, 47 struct thermal_cooling_device *cdev, int percentage, int level) 48 { 49 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips); 50 } 51 52 /** 53 * fair_share_throttle - throttles devices associated with the given zone 54 * @tz: thermal_zone_device 55 * @trip: trip point 56 * 57 * Throttling Logic: This uses three parameters to calculate the new 58 * throttle state of the cooling devices associated with the given zone. 59 * 60 * Parameters used for Throttling: 61 * P1. max_state: Maximum throttle state exposed by the cooling device. 62 * P2. percentage[i]/100: 63 * How 'effective' the 'i'th device is, in cooling the given zone. 64 * P3. cur_trip_level/max_no_of_trips: 65 * This describes the extent to which the devices should be throttled. 66 * We do not want to throttle too much when we trip a lower temperature, 67 * whereas the throttling is at full swing if we trip critical levels. 68 * (Heavily assumes the trip points are in ascending order) 69 * new_state of cooling device = P3 * P2 * P1 70 */ 71 static int fair_share_throttle(struct thermal_zone_device *tz, 72 const struct thermal_trip *trip) 73 { 74 struct thermal_instance *instance; 75 int total_weight = 0; 76 int total_instance = 0; 77 int cur_trip_level = get_trip_level(tz); 78 79 lockdep_assert_held(&tz->lock); 80 81 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 82 if (instance->trip != trip) 83 continue; 84 85 total_weight += instance->weight; 86 total_instance++; 87 } 88 89 list_for_each_entry(instance, &tz->thermal_instances, tz_node) { 90 int percentage; 91 struct thermal_cooling_device *cdev = instance->cdev; 92 93 if (instance->trip != trip) 94 continue; 95 96 if (!total_weight) 97 percentage = 100 / total_instance; 98 else 99 percentage = (instance->weight * 100) / total_weight; 100 101 instance->target = get_target_state(tz, cdev, percentage, 102 cur_trip_level); 103 104 mutex_lock(&cdev->lock); 105 __thermal_cdev_update(cdev); 106 mutex_unlock(&cdev->lock); 107 } 108 109 return 0; 110 } 111 112 static struct thermal_governor thermal_gov_fair_share = { 113 .name = "fair_share", 114 .throttle = fair_share_throttle, 115 }; 116 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); 117