drivers/thermal/gov_fair_share.c

   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);