Commit 445936f9 authored by Daniel Lezcano's avatar Daniel Lezcano Committed by Rafael J. Wysocki
Browse files

thermal: core: Add user thresholds support 



The user thresholds mechanism is a way to have the userspace to tell
the thermal framework to send a notification when a temperature limit
is crossed. There is no id, no hysteresis, just the temperature and
the direction of the limit crossing. That means we can be notified
when a threshold is crossed the way up only, or the way down only or
both ways. That allows to create hysteresis values if it is needed.

A threshold can be added, deleted or flushed. The latter means all
thresholds belonging to a thermal zone will be deleted.

When a threshold is added:

 - if the same threshold (temperature and direction) exists, an error
   is returned

 - if a threshold is specified with the same temperature but a
   different direction, the specified direction is added

 - if there is no threshold with the same temperature then it is
   created

When a threshold is deleted:

 - if the same threshold (temperature and direction) exists, it is
   deleted

 - if a threshold is specified with the same temperature but a
   different direction, the specified direction is removed

 - if there is no threshold with the same temperature, then an error
   is returned

When the threshold are flushed:

 - All thresholds related to a thermal zone are deleted

When a threshold is crossed:

 - the userspace does not need to know which threshold(s) have been
   crossed, it will be notified with the current temperature and the
   previous temperature

 - if multiple thresholds have been crossed between two updates only
   one notification will be send to the userspace, it is pointless to
   send a notification per thresholds crossed as the userspace can
   handle that easily when it has the temperature delta information

Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20240923100005.2532430-2-daniel.lezcano@linaro.org


[ rjw: Subject edit, use BIT(0) and BIT(1) in symbol definitions ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 827a0752

drivers/thermal/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ CFLAGS_thermal_core.o := -I$(src) 
obj-$(CONFIG_THERMAL)		+= thermal_sys.o

thermal_sys-y			+= thermal_core.o thermal_sysfs.o

thermal_sys-y			+= thermal_trip.o thermal_helpers.o

thermal_sys-y			+= thermal_thresholds.o



# netlink interface to manage the thermal framework

thermal_sys-$(CONFIG_THERMAL_NETLINK)		+= thermal_netlink.o

drivers/thermal/thermal_core.h

+2 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/thermal.h>



#include "thermal_netlink.h"

#include "thermal_thresholds.h"

#include "thermal_debugfs.h"



struct thermal_attr {
@@ -139,6 +140,7 @@ struct thermal_zone_device { 
#ifdef CONFIG_THERMAL_DEBUGFS

	struct thermal_debugfs *debugfs;

#endif

	struct list_head user_thresholds;

	struct thermal_trip_desc trips[] __counted_by(num_trips);

};

drivers/thermal/thermal_thresholds.c

0 → 100644
+229 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright 2024 Linaro Limited

 *

 * Author: Daniel Lezcano <daniel.lezcano@linaro.org>

 *

 * Thermal thresholds

 */

#include <linux/list.h>

#include <linux/list_sort.h>

#include <linux/slab.h>



#include "thermal_core.h"

#include "thermal_thresholds.h"



int thermal_thresholds_init(struct thermal_zone_device *tz)

{

	INIT_LIST_HEAD(&tz->user_thresholds);



	return 0;

}



void thermal_thresholds_flush(struct thermal_zone_device *tz)

{

	struct list_head *thresholds = &tz->user_thresholds;

	struct user_threshold *entry, *tmp;



	lockdep_assert_held(&tz->lock);



	list_for_each_entry_safe(entry, tmp, thresholds, list_node) {

		list_del(&entry->list_node);

		kfree(entry);

	}



	__thermal_zone_device_update(tz, THERMAL_TZ_FLUSH_THRESHOLDS);

}



void thermal_thresholds_exit(struct thermal_zone_device *tz)

{

	thermal_thresholds_flush(tz);

}



static int __thermal_thresholds_cmp(void *data,

				    const struct list_head *l1,

				    const struct list_head *l2)

{

	struct user_threshold *t1 = container_of(l1, struct user_threshold, list_node);

	struct user_threshold *t2 = container_of(l2, struct user_threshold, list_node);



	return t1->temperature - t2->temperature;

}



static struct user_threshold *__thermal_thresholds_find(const struct list_head *thresholds,

							int temperature)

{

	struct user_threshold *t;



	list_for_each_entry(t, thresholds, list_node)

		if (t->temperature == temperature)

			return t;



	return NULL;

}



static bool __thermal_threshold_is_crossed(struct user_threshold *threshold, int temperature,

					   int last_temperature, int direction,

					   int *low, int *high)

{



	if (temperature >= threshold->temperature) {

		if (threshold->temperature > *low &&

		    THERMAL_THRESHOLD_WAY_DOWN & threshold->direction)

			*low = threshold->temperature;



		if (last_temperature < threshold->temperature &&

		    threshold->direction & direction)

			return true;

	} else {

		if (threshold->temperature < *high && THERMAL_THRESHOLD_WAY_UP

		    & threshold->direction)

			*high = threshold->temperature;



		if (last_temperature >= threshold->temperature &&

		    threshold->direction & direction)

			return true;

	}



	return false;

}



static bool thermal_thresholds_handle_raising(struct list_head *thresholds, int temperature,

					      int last_temperature, int *low, int *high)

{

	struct user_threshold *t;



	list_for_each_entry(t, thresholds, list_node) {

		if (__thermal_threshold_is_crossed(t, temperature, last_temperature,

						   THERMAL_THRESHOLD_WAY_UP, low, high))

			return true;

	}



	return false;

}



static bool thermal_thresholds_handle_dropping(struct list_head *thresholds, int temperature,

					       int last_temperature, int *low, int *high)

{

	struct user_threshold *t;



	list_for_each_entry_reverse(t, thresholds, list_node) {

		if (__thermal_threshold_is_crossed(t, temperature, last_temperature,

						   THERMAL_THRESHOLD_WAY_DOWN, low, high))

			return true;

	}



	return false;

}



void thermal_thresholds_handle(struct thermal_zone_device *tz, int *low, int *high)

{

	struct list_head *thresholds = &tz->user_thresholds;



	int temperature = tz->temperature;

	int last_temperature = tz->last_temperature;

	bool notify;



	lockdep_assert_held(&tz->lock);



	/*

	 * We need a second update in order to detect a threshold being crossed

	 */

	if (last_temperature == THERMAL_TEMP_INVALID)

		return;



	/*

	 * The temperature is stable, so obviously we can not have

	 * crossed a threshold.

	 */

	if (last_temperature == temperature)

		return;



	/*

	 * Since last update the temperature:

	 * - increased : thresholds are crossed the way up

	 * - decreased : thresholds are crossed the way down

	 */

	if (temperature > last_temperature)

		notify = thermal_thresholds_handle_raising(thresholds, temperature,

							   last_temperature, low, high);

	else

		notify = thermal_thresholds_handle_dropping(thresholds, temperature,

							    last_temperature, low, high);



	if (notify)

		pr_debug("A threshold has been crossed the way %s, with a temperature=%d, last_temperature=%d\n",

			 temperature > last_temperature ? "up" : "down", temperature, last_temperature);

}



int thermal_thresholds_add(struct thermal_zone_device *tz, int temperature, int direction)

{

	struct list_head *thresholds = &tz->user_thresholds;

	struct user_threshold *t;



	lockdep_assert_held(&tz->lock);



	t = __thermal_thresholds_find(thresholds, temperature);

	if (t) {

		if (t->direction == direction)

			return -EEXIST;



		t->direction |= direction;

	} else {



		t = kmalloc(sizeof(*t), GFP_KERNEL);

		if (!t)

			return -ENOMEM;



		INIT_LIST_HEAD(&t->list_node);

		t->temperature = temperature;

		t->direction = direction;

		list_add(&t->list_node, thresholds);

		list_sort(NULL, thresholds, __thermal_thresholds_cmp);

	}



	__thermal_zone_device_update(tz, THERMAL_TZ_ADD_THRESHOLD);



	return 0;

}



int thermal_thresholds_delete(struct thermal_zone_device *tz, int temperature, int direction)

{

	struct list_head *thresholds = &tz->user_thresholds;

	struct user_threshold *t;



	lockdep_assert_held(&tz->lock);



	t = __thermal_thresholds_find(thresholds, temperature);

	if (!t)

		return -ENOENT;



	if (t->direction == direction) {

		list_del(&t->list_node);

		kfree(t);

	} else {

		t->direction &= ~direction;

	}



	__thermal_zone_device_update(tz, THERMAL_TZ_DEL_THRESHOLD);



	return 0;

}



int thermal_thresholds_for_each(struct thermal_zone_device *tz,

				int (*cb)(struct user_threshold *, void *arg), void *arg)

{

	struct list_head *thresholds = &tz->user_thresholds;

	struct user_threshold *entry;

	int ret;



	lockdep_assert_held(&tz->lock);



	list_for_each_entry(entry, thresholds, list_node) {

		ret = cb(entry, arg);

		if (ret)

			return ret;

	}



	return 0;

}

drivers/thermal/thermal_thresholds.h

0 → 100644
+19 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __THERMAL_THRESHOLDS_H__

#define __THERMAL_THRESHOLDS_H__



struct user_threshold {

	struct list_head list_node;

	int temperature;

	int direction;

};



int thermal_thresholds_init(struct thermal_zone_device *tz);

void thermal_thresholds_exit(struct thermal_zone_device *tz);

void thermal_thresholds_flush(struct thermal_zone_device *tz);

void thermal_thresholds_handle(struct thermal_zone_device *tz, int *low, int *high);

int thermal_thresholds_add(struct thermal_zone_device *tz, int temperature, int direction);

int thermal_thresholds_delete(struct thermal_zone_device *tz, int temperature, int direction);

int thermal_thresholds_for_each(struct thermal_zone_device *tz,

				int (*cb)(struct user_threshold *, void *arg), void *arg);

#endif

include/linux/thermal.h

+3 −0
Original line number Diff line number Diff line
@@ -56,6 +56,9 @@ enum thermal_notify_event { 
	THERMAL_TZ_UNBIND_CDEV, /* Cooling dev is unbind from the thermal zone */

	THERMAL_INSTANCE_WEIGHT_CHANGED, /* Thermal instance weight changed */

	THERMAL_TZ_RESUME, /* Thermal zone is resuming after system sleep */

	THERMAL_TZ_ADD_THRESHOLD, /* Threshold added */

	THERMAL_TZ_DEL_THRESHOLD, /* Threshold deleted */

	THERMAL_TZ_FLUSH_THRESHOLDS, /* All thresholds deleted */

};



/**