drivers/thermal/thermal_helpers.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  thermal_helpers.c - helper functions to handle thermal devices
   4  *
   5  *  Copyright (C) 2016 Eduardo Valentin <edubezval@gmail.com>
   6  *
   7  *  Highly based on original thermal_core.c
   8  *  Copyright (C) 2008 Intel Corp
   9  *  Copyright (C) 2008 Zhang Rui <rui.zhang@intel.com>
  10  *  Copyright (C) 2008 Sujith Thomas <sujith.thomas@intel.com>
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/export.h>
  18 #include <linux/slab.h>
  19 #include <linux/string.h>
  20 #include <linux/sysfs.h>
  21
  22 #include <trace/events/thermal.h>
  23
  24 #include "thermal_core.h"
  25
  26 int get_tz_trend(struct thermal_zone_device *tz, int trip)
  27 {
  28         enum thermal_trend trend;
  29
  30         if (tz->emul_temperature || !tz->ops->get_trend ||
  31             tz->ops->get_trend(tz, trip, &trend)) {
  32                 if (tz->temperature > tz->last_temperature)
  33                         trend = THERMAL_TREND_RAISING;
  34                 else if (tz->temperature < tz->last_temperature)
  35                         trend = THERMAL_TREND_DROPPING;
  36                 else
  37                         trend = THERMAL_TREND_STABLE;
  38         }
  39
  40         return trend;
  41 }
  42 EXPORT_SYMBOL(get_tz_trend);
  43
  44 struct thermal_instance *
  45 get_thermal_instance(struct thermal_zone_device *tz,
  46                      struct thermal_cooling_device *cdev, int trip)
  47 {
  48         struct thermal_instance *pos = NULL;
  49         struct thermal_instance *target_instance = NULL;
  50
  51         mutex_lock(&tz->lock);
  52         mutex_lock(&cdev->lock);
  53
  54         list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
  55                 if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
  56                         target_instance = pos;
  57                         break;
  58                 }
  59         }
  60
  61         mutex_unlock(&cdev->lock);
  62         mutex_unlock(&tz->lock);
  63
  64         return target_instance;
  65 }
  66 EXPORT_SYMBOL(get_thermal_instance);
  67
  68 /**
  69  * thermal_zone_get_temp() - returns the temperature of a thermal zone
  70  * @tz: a valid pointer to a struct thermal_zone_device
  71  * @temp: a valid pointer to where to store the resulting temperature.
  72  *
  73  * When a valid thermal zone reference is passed, it will fetch its
  74  * temperature and fill @temp.
  75  *
  76  * Return: On success returns 0, an error code otherwise
  77  */
  78 int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
  79 {
  80         int ret = -EINVAL;
  81         int count;
  82         int crit_temp = INT_MAX;
  83         enum thermal_trip_type type;
  84
  85         if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
  86                 goto exit;
  87
  88         mutex_lock(&tz->lock);
  89
  90         ret = tz->ops->get_temp(tz, temp);
  91
  92         if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
  93                 for (count = 0; count < tz->trips; count++) {
  94                         ret = tz->ops->get_trip_type(tz, count, &type);
  95                         if (!ret && type == THERMAL_TRIP_CRITICAL) {
  96                                 ret = tz->ops->get_trip_temp(tz, count,
  97                                                 &crit_temp);
  98                                 break;
  99                         }
 100                 }
 101
 102                 /*
 103                  * Only allow emulating a temperature when the real temperature
 104                  * is below the critical temperature so that the emulation code
 105                  * cannot hide critical conditions.
 106                  */
 107                 if (!ret && *temp < crit_temp)
 108                         *temp = tz->emul_temperature;
 109         }
 110
 111         mutex_unlock(&tz->lock);
 112 exit:
 113         return ret;
 114 }
 115 EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
 116
 117 /**
 118  * thermal_zone_set_trips - Computes the next trip points for the driver
 119  * @tz: a pointer to a thermal zone device structure
 120  *
 121  * The function computes the next temperature boundaries by browsing
 122  * the trip points. The result is the closer low and high trip points
 123  * to the current temperature. These values are passed to the backend
 124  * driver to let it set its own notification mechanism (usually an
 125  * interrupt).
 126  *
 127  * It does not return a value
 128  */
 129 void thermal_zone_set_trips(struct thermal_zone_device *tz)
 130 {
 131         int low = -INT_MAX;
 132         int high = INT_MAX;
 133         int trip_temp, hysteresis;
 134         int i, ret;
 135
 136         mutex_lock(&tz->lock);
 137
 138         if (!tz->ops->set_trips || !tz->ops->get_trip_hyst)
 139                 goto exit;
 140
 141         for (i = 0; i < tz->trips; i++) {
 142                 int trip_low;
 143
 144                 tz->ops->get_trip_temp(tz, i, &trip_temp);
 145                 tz->ops->get_trip_hyst(tz, i, &hysteresis);
 146
 147                 trip_low = trip_temp - hysteresis;
 148
 149                 if (trip_low < tz->temperature && trip_low > low)
 150                         low = trip_low;
 151
 152                 if (trip_temp > tz->temperature && trip_temp < high)
 153                         high = trip_temp;
 154         }
 155
 156         /* No need to change trip points */
 157         if (tz->prev_low_trip == low && tz->prev_high_trip == high)
 158                 goto exit;
 159
 160         tz->prev_low_trip = low;
 161         tz->prev_high_trip = high;
 162
 163         dev_dbg(&tz->device,
 164                 "new temperature boundaries: %d < x < %d\n", low, high);
 165
 166         /*
 167          * Set a temperature window. When this window is left the driver
 168          * must inform the thermal core via thermal_zone_device_update.
 169          */
 170         ret = tz->ops->set_trips(tz, low, high);
 171         if (ret)
 172                 dev_err(&tz->device, "Failed to set trips: %d\n", ret);
 173
 174 exit:
 175         mutex_unlock(&tz->lock);
 176 }
 177
 178 static void thermal_cdev_set_cur_state(struct thermal_cooling_device *cdev,
 179                                        int target)
 180 {
 181         if (cdev->ops->set_cur_state(cdev, target))
 182                 return;
 183
 184         thermal_notify_cdev_state_update(cdev->id, target);
 185         thermal_cooling_device_stats_update(cdev, target);
 186 }
 187
 188 void thermal_cdev_update(struct thermal_cooling_device *cdev)
 189 {
 190         struct thermal_instance *instance;
 191         unsigned long target = 0;
 192
 193         mutex_lock(&cdev->lock);
 194         /* cooling device is updated*/
 195         if (cdev->updated) {
 196                 mutex_unlock(&cdev->lock);
 197                 return;
 198         }
 199
 200         /* Make sure cdev enters the deepest cooling state */
 201         list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
 202                 dev_dbg(&cdev->device, "zone%d->target=%lu\n",
 203                         instance->tz->id, instance->target);
 204                 if (instance->target == THERMAL_NO_TARGET)
 205                         continue;
 206                 if (instance->target > target)
 207                         target = instance->target;
 208         }
 209
 210         thermal_cdev_set_cur_state(cdev, target);
 211
 212         cdev->updated = true;
 213         mutex_unlock(&cdev->lock);
 214         trace_cdev_update(cdev, target);
 215         dev_dbg(&cdev->device, "set to state %lu\n", target);
 216 }
 217 EXPORT_SYMBOL(thermal_cdev_update);
 218
 219 /**
 220  * thermal_zone_get_slope - return the slope attribute of the thermal zone
 221  * @tz: thermal zone device with the slope attribute
 222  *
 223  * Return: If the thermal zone device has a slope attribute, return it, else
 224  * return 1.
 225  */
 226 int thermal_zone_get_slope(struct thermal_zone_device *tz)
 227 {
 228         if (tz && tz->tzp)
 229                 return tz->tzp->slope;
 230         return 1;
 231 }
 232 EXPORT_SYMBOL_GPL(thermal_zone_get_slope);
 233
 234 /**
 235  * thermal_zone_get_offset - return the offset attribute of the thermal zone
 236  * @tz: thermal zone device with the offset attribute
 237  *
 238  * Return: If the thermal zone device has a offset attribute, return it, else
 239  * return 0.
 240  */
 241 int thermal_zone_get_offset(struct thermal_zone_device *tz)
 242 {
 243         if (tz && tz->tzp)
 244                 return tz->tzp->offset;
 245         return 0;
 246 }
 247 EXPORT_SYMBOL_GPL(thermal_zone_get_offset);