LXR linux/drivers/thermal/fair

   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 <trace/events/thermal.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 */
  22static int get_trip_level(struct thermal_zone_device *tz)
  23{
  24        int count = 0;
  25        int trip_temp;
  26        enum thermal_trip_type trip_type;
  27
  28        if (tz->trips == 0 || !tz->ops->get_trip_temp)
  29                return 0;
  30
  31        for (count = 0; count < tz->trips; count++) {
  32                tz->ops->get_trip_temp(tz, count, &trip_temp);
  33                if (tz->temperature < trip_temp)
  34                        break;
  35        }
  36
  37        /*
  38         * count > 0 only if temperature is greater than first trip
  39         * point, in which case, trip_point = count - 1
  40         */
  41        if (count > 0) {
  42                tz->ops->get_trip_type(tz, count - 1, &trip_type);
  43                trace_thermal_zone_trip(tz, count - 1, trip_type);
  44        }
  45
  46        return count;
  47}
  48
  49static long get_target_state(struct thermal_zone_device *tz,
  50                struct thermal_cooling_device *cdev, int percentage, int level)
  51{
  52        unsigned long max_state;
  53
  54        cdev->ops->get_max_state(cdev, &max_state);
  55
  56        return (long)(percentage * level * max_state) / (100 * tz->trips);
  57}
  58
  59/**
  60 * fair_share_throttle - throttles devices associated with the given zone
  61 * @tz - thermal_zone_device
  62 * @trip - trip point index
  63 *
  64 * Throttling Logic: This uses three parameters to calculate the new
  65 * throttle state of the cooling devices associated with the given zone.
  66 *
  67 * Parameters used for Throttling:
  68 * P1. max_state: Maximum throttle state exposed by the cooling device.
  69 * P2. percentage[i]/100:
  70 *      How 'effective' the 'i'th device is, in cooling the given zone.
  71 * P3. cur_trip_level/max_no_of_trips:
  72 *      This describes the extent to which the devices should be throttled.
  73 *      We do not want to throttle too much when we trip a lower temperature,
  74 *      whereas the throttling is at full swing if we trip critical levels.
  75 *      (Heavily assumes the trip points are in ascending order)
  76 * new_state of cooling device = P3 * P2 * P1
  77 */
  78static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
  79{
  80        struct thermal_instance *instance;
  81        int total_weight = 0;
  82        int total_instance = 0;
  83        int cur_trip_level = get_trip_level(tz);
  84
  85        list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  86                if (instance->trip != trip)
  87                        continue;
  88
  89                total_weight += instance->weight;
  90                total_instance++;
  91        }
  92
  93        list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  94                int percentage;
  95                struct thermal_cooling_device *cdev = instance->cdev;
  96
  97                if (instance->trip != trip)
  98                        continue;
  99
 100                if (!total_weight)
 101                        percentage = 100 / total_instance;
 102                else
 103                        percentage = (instance->weight * 100) / total_weight;
 104
 105                instance->target = get_target_state(tz, cdev, percentage,
 106                                                    cur_trip_level);
 107
 108                mutex_lock(&instance->cdev->lock);
 109                instance->cdev->updated = false;
 110                mutex_unlock(&instance->cdev->lock);
 111                thermal_cdev_update(cdev);
 112        }
 113        return 0;
 114}
 115
 116static struct thermal_governor thermal_gov_fair_share = {
 117        .name           = "fair_share",
 118        .throttle       = fair_share_throttle,
 119};
 120THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);
 121