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 = -1;
  22
  23         for_each_trip(tz, trip) {
  24                 if (trip->temperature >= tz->temperature)
  25                         continue;
  26
  27                 trip_level++;
  28
  29                 if (!level_trip || trip->temperature > level_trip->temperature)
  30                         level_trip = trip;
  31         }
  32
  33         /*  Bail out if the temperature is not greater than any trips. */
  34         if (trip_level < 0)
  35                 return 0;
  36
  37         trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, level_trip),
  38                                 level_trip->type);
  39
  40         return trip_level;
  41 }
  42
  43 static long get_target_state(struct thermal_zone_device *tz,
  44                 struct thermal_cooling_device *cdev, int percentage, int level)
  45 {
  46         return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips);
  47 }
  48
  49 /**
  50  * fair_share_throttle - throttles devices associated with the given zone
  51  * @tz: thermal_zone_device
  52  * @trip: trip point
  53  *
  54  * Throttling Logic: This uses three parameters to calculate the new
  55  * throttle state of the cooling devices associated with the given zone.
  56  *
  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
  67  */
  68 static int fair_share_throttle(struct thermal_zone_device *tz,
  69                                const struct thermal_trip *trip)
  70 {
  71         struct thermal_instance *instance;
  72         int total_weight = 0;
  73         int total_instance = 0;
  74         int cur_trip_level = get_trip_level(tz);
  75
  76         lockdep_assert_held(&tz->lock);
  77
  78         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  79                 if (instance->trip != trip)
  80                         continue;
  81
  82                 total_weight += instance->weight;
  83                 total_instance++;
  84         }
  85
  86         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  87                 int percentage;
  88                 struct thermal_cooling_device *cdev = instance->cdev;
  89
  90                 if (instance->trip != trip)
  91                         continue;
  92
  93                 if (!total_weight)
  94                         percentage = 100 / total_instance;
  95                 else
  96                         percentage = (instance->weight * 100) / total_weight;
  97
  98                 instance->target = get_target_state(tz, cdev, percentage,
  99                                                     cur_trip_level);
 100
 101                 mutex_lock(&cdev->lock);
 102                 __thermal_cdev_update(cdev);
 103                 mutex_unlock(&cdev->lock);
 104         }
 105
 106         return 0;
 107 }
 108
 109 static struct thermal_governor thermal_gov_fair_share = {
 110         .name           = "fair_share",
 111         .throttle       = fair_share_throttle,
 112 };
 113 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);