1 // SPDX-License-Identifier: GPL-2.0-only
3 * fair_share.c - A simple weight based Thermal governor
5 * Copyright (C) 2012 Intel Corp
6 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
8 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
10 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
13 #include <linux/thermal.h>
14 #include <trace/events/thermal.h>
16 #include "thermal_core.h"
19 * get_trip_level: - obtains the current trip level for a zone
20 * @tz: thermal zone device
22 static int get_trip_level(struct thermal_zone_device *tz)
26 enum thermal_trip_type trip_type;
28 if (tz->num_trips == 0 || !tz->ops->get_trip_temp)
31 for (count = 0; count < tz->num_trips; count++) {
32 tz->ops->get_trip_temp(tz, count, &trip_temp);
33 if (tz->temperature < trip_temp)
38 * count > 0 only if temperature is greater than first trip
39 * point, in which case, trip_point = count - 1
42 tz->ops->get_trip_type(tz, count - 1, &trip_type);
43 trace_thermal_zone_trip(tz, count - 1, trip_type);
49 static long get_target_state(struct thermal_zone_device *tz,
50 struct thermal_cooling_device *cdev, int percentage, int level)
52 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips);
56 * fair_share_throttle - throttles devices associated with the given zone
57 * @tz: thermal_zone_device
58 * @trip: trip point index
60 * Throttling Logic: This uses three parameters to calculate the new
61 * throttle state of the cooling devices associated with the given zone.
63 * Parameters used for Throttling:
64 * P1. max_state: Maximum throttle state exposed by the cooling device.
65 * P2. percentage[i]/100:
66 * How 'effective' the 'i'th device is, in cooling the given zone.
67 * P3. cur_trip_level/max_no_of_trips:
68 * This describes the extent to which the devices should be throttled.
69 * We do not want to throttle too much when we trip a lower temperature,
70 * whereas the throttling is at full swing if we trip critical levels.
71 * (Heavily assumes the trip points are in ascending order)
72 * new_state of cooling device = P3 * P2 * P1
74 static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
76 struct thermal_instance *instance;
78 int total_instance = 0;
79 int cur_trip_level = get_trip_level(tz);
81 mutex_lock(&tz->lock);
83 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
84 if (instance->trip != trip)
87 total_weight += instance->weight;
91 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
93 struct thermal_cooling_device *cdev = instance->cdev;
95 if (instance->trip != trip)
99 percentage = 100 / total_instance;
101 percentage = (instance->weight * 100) / total_weight;
103 instance->target = get_target_state(tz, cdev, percentage,
106 mutex_lock(&cdev->lock);
107 __thermal_cdev_update(cdev);
108 mutex_unlock(&cdev->lock);
111 mutex_unlock(&tz->lock);
115 static struct thermal_governor thermal_gov_fair_share = {
116 .name = "fair_share",
117 .throttle = fair_share_throttle,
119 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);