linux/drivers/thermal/thermal_helpers.c
Lukasz Luba b70dbf40eb thermal/core: Create a helper __thermal_cdev_update() without a lock
There is a need to have a helper function which updates cooling device
state from the governors code. With this change governor can use
lock and unlock while calling helper function. This avoid unnecessary
second time lock/unlock which was in previous solution present in
governor implementation. This new helper function must be called
with mutex 'cdev->lock' hold.

The changed been discussed and part of code presented in thread:
https://lore.kernel.org/linux-pm/20210419084536.25000-1-lukasz.luba@arm.com/

Co-developed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20210422114308.29684-2-lukasz.luba@arm.com
2021-04-22 14:10:28 +02:00

262 lines
6.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* thermal_helpers.c - helper functions to handle thermal devices
*
* Copyright (C) 2016 Eduardo Valentin <edubezval@gmail.com>
*
* Highly based on original thermal_core.c
* Copyright (C) 2008 Intel Corp
* Copyright (C) 2008 Zhang Rui <rui.zhang@intel.com>
* Copyright (C) 2008 Sujith Thomas <sujith.thomas@intel.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <trace/events/thermal.h>
#include "thermal_core.h"
int get_tz_trend(struct thermal_zone_device *tz, int trip)
{
enum thermal_trend trend;
if (tz->emul_temperature || !tz->ops->get_trend ||
tz->ops->get_trend(tz, trip, &trend)) {
if (tz->temperature > tz->last_temperature)
trend = THERMAL_TREND_RAISING;
else if (tz->temperature < tz->last_temperature)
trend = THERMAL_TREND_DROPPING;
else
trend = THERMAL_TREND_STABLE;
}
return trend;
}
EXPORT_SYMBOL(get_tz_trend);
struct thermal_instance *
get_thermal_instance(struct thermal_zone_device *tz,
struct thermal_cooling_device *cdev, int trip)
{
struct thermal_instance *pos = NULL;
struct thermal_instance *target_instance = NULL;
mutex_lock(&tz->lock);
mutex_lock(&cdev->lock);
list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
target_instance = pos;
break;
}
}
mutex_unlock(&cdev->lock);
mutex_unlock(&tz->lock);
return target_instance;
}
EXPORT_SYMBOL(get_thermal_instance);
/**
* thermal_zone_get_temp() - returns the temperature of a thermal zone
* @tz: a valid pointer to a struct thermal_zone_device
* @temp: a valid pointer to where to store the resulting temperature.
*
* When a valid thermal zone reference is passed, it will fetch its
* temperature and fill @temp.
*
* Return: On success returns 0, an error code otherwise
*/
int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
{
int ret = -EINVAL;
int count;
int crit_temp = INT_MAX;
enum thermal_trip_type type;
if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
goto exit;
mutex_lock(&tz->lock);
ret = tz->ops->get_temp(tz, temp);
if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
for (count = 0; count < tz->trips; count++) {
ret = tz->ops->get_trip_type(tz, count, &type);
if (!ret && type == THERMAL_TRIP_CRITICAL) {
ret = tz->ops->get_trip_temp(tz, count,
&crit_temp);
break;
}
}
/*
* Only allow emulating a temperature when the real temperature
* is below the critical temperature so that the emulation code
* cannot hide critical conditions.
*/
if (!ret && *temp < crit_temp)
*temp = tz->emul_temperature;
}
mutex_unlock(&tz->lock);
exit:
return ret;
}
EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
/**
* thermal_zone_set_trips - Computes the next trip points for the driver
* @tz: a pointer to a thermal zone device structure
*
* The function computes the next temperature boundaries by browsing
* the trip points. The result is the closer low and high trip points
* to the current temperature. These values are passed to the backend
* driver to let it set its own notification mechanism (usually an
* interrupt).
*
* It does not return a value
*/
void thermal_zone_set_trips(struct thermal_zone_device *tz)
{
int low = -INT_MAX;
int high = INT_MAX;
int trip_temp, hysteresis;
int i, ret;
mutex_lock(&tz->lock);
if (!tz->ops->set_trips || !tz->ops->get_trip_hyst)
goto exit;
for (i = 0; i < tz->trips; i++) {
int trip_low;
tz->ops->get_trip_temp(tz, i, &trip_temp);
tz->ops->get_trip_hyst(tz, i, &hysteresis);
trip_low = trip_temp - hysteresis;
if (trip_low < tz->temperature && trip_low > low)
low = trip_low;
if (trip_temp > tz->temperature && trip_temp < high)
high = trip_temp;
}
/* No need to change trip points */
if (tz->prev_low_trip == low && tz->prev_high_trip == high)
goto exit;
tz->prev_low_trip = low;
tz->prev_high_trip = high;
dev_dbg(&tz->device,
"new temperature boundaries: %d < x < %d\n", low, high);
/*
* Set a temperature window. When this window is left the driver
* must inform the thermal core via thermal_zone_device_update.
*/
ret = tz->ops->set_trips(tz, low, high);
if (ret)
dev_err(&tz->device, "Failed to set trips: %d\n", ret);
exit:
mutex_unlock(&tz->lock);
}
void thermal_set_delay_jiffies(unsigned long *delay_jiffies, int delay_ms)
{
*delay_jiffies = msecs_to_jiffies(delay_ms);
if (delay_ms > 1000)
*delay_jiffies = round_jiffies(*delay_jiffies);
}
static void thermal_cdev_set_cur_state(struct thermal_cooling_device *cdev,
int target)
{
if (cdev->ops->set_cur_state(cdev, target))
return;
thermal_notify_cdev_state_update(cdev->id, target);
thermal_cooling_device_stats_update(cdev, target);
}
void __thermal_cdev_update(struct thermal_cooling_device *cdev)
{
struct thermal_instance *instance;
unsigned long target = 0;
/* Make sure cdev enters the deepest cooling state */
list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
dev_dbg(&cdev->device, "zone%d->target=%lu\n",
instance->tz->id, instance->target);
if (instance->target == THERMAL_NO_TARGET)
continue;
if (instance->target > target)
target = instance->target;
}
thermal_cdev_set_cur_state(cdev, target);
trace_cdev_update(cdev, target);
dev_dbg(&cdev->device, "set to state %lu\n", target);
}
/**
* thermal_cdev_update - update cooling device state if needed
* @cdev: pointer to struct thermal_cooling_device
*
* Update the cooling device state if there is a need.
*/
void thermal_cdev_update(struct thermal_cooling_device *cdev)
{
mutex_lock(&cdev->lock);
if (!cdev->updated) {
__thermal_cdev_update(cdev);
cdev->updated = true;
}
mutex_unlock(&cdev->lock);
}
EXPORT_SYMBOL(thermal_cdev_update);
/**
* thermal_zone_get_slope - return the slope attribute of the thermal zone
* @tz: thermal zone device with the slope attribute
*
* Return: If the thermal zone device has a slope attribute, return it, else
* return 1.
*/
int thermal_zone_get_slope(struct thermal_zone_device *tz)
{
if (tz && tz->tzp)
return tz->tzp->slope;
return 1;
}
EXPORT_SYMBOL_GPL(thermal_zone_get_slope);
/**
* thermal_zone_get_offset - return the offset attribute of the thermal zone
* @tz: thermal zone device with the offset attribute
*
* Return: If the thermal zone device has a offset attribute, return it, else
* return 0.
*/
int thermal_zone_get_offset(struct thermal_zone_device *tz)
{
if (tz && tz->tzp)
return tz->tzp->offset;
return 0;
}
EXPORT_SYMBOL_GPL(thermal_zone_get_offset);