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 "thermal_trace.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)
24 struct thermal_trip trip;
27 for (count = 0; count < tz->num_trips; count++) {
28 __thermal_zone_get_trip(tz, count, &trip);
29 if (tz->temperature < trip.temperature)
34 * count > 0 only if temperature is greater than first trip
35 * point, in which case, trip_point = count - 1
38 trace_thermal_zone_trip(tz, count - 1, trip.type);
43 static long get_target_state(struct thermal_zone_device *tz,
44 struct thermal_cooling_device *cdev, int percentage, int level)
46 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips);
50 * fair_share_throttle - throttles devices associated with the given zone
51 * @tz: thermal_zone_device
52 * @trip_index: trip point index
54 * Throttling Logic: This uses three parameters to calculate the new
55 * throttle state of the cooling devices associated with the given zone.
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
68 static int fair_share_throttle(struct thermal_zone_device *tz, int trip_index)
70 const struct thermal_trip *trip = &tz->trips[trip_index];
71 struct thermal_instance *instance;
73 int total_instance = 0;
74 int cur_trip_level = get_trip_level(tz);
76 lockdep_assert_held(&tz->lock);
78 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
79 if (instance->trip != trip)
82 total_weight += instance->weight;
86 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
88 struct thermal_cooling_device *cdev = instance->cdev;
90 if (instance->trip != trip)
94 percentage = 100 / total_instance;
96 percentage = (instance->weight * 100) / total_weight;
98 instance->target = get_target_state(tz, cdev, percentage,
101 mutex_lock(&cdev->lock);
102 __thermal_cdev_update(cdev);
103 mutex_unlock(&cdev->lock);
109 static struct thermal_governor thermal_gov_fair_share = {
110 .name = "fair_share",
111 .throttle = fair_share_throttle,
113 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);