drivers/thermal/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 <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  */
  22 static 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
  49 static 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  */
  78 static 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
 116 static struct thermal_governor thermal_gov_fair_share = {
 117         .name           = "fair_share",
 118         .throttle       = fair_share_throttle,
 119 };
 120 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);