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dlezcanorafaeljw
dlezcano
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rafaeljw
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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: Daniel Lezcano <[email protected]> Link: https://patch.msgid.link/[email protected] [ rjw: Subject edit, use BIT(0) and BIT(1) in symbol definitions ] Signed-off-by: Rafael J. Wysocki <[email protected]>
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‎drivers/thermal/Makefile‎

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@@ -6,6 +6,7 @@ CFLAGS_thermal_core.o := -I$(src)
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obj-$(CONFIG_THERMAL) += thermal_sys.o
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thermal_sys-y += thermal_core.o thermal_sysfs.o
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thermal_sys-y += thermal_trip.o thermal_helpers.o
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thermal_sys-y += thermal_thresholds.o
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# netlink interface to manage the thermal framework
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thermal_sys-$(CONFIG_THERMAL_NETLINK) += thermal_netlink.o

‎drivers/thermal/thermal_core.h‎

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@@ -13,6 +13,7 @@
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#include <linux/thermal.h>
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#include "thermal_netlink.h"
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#include "thermal_thresholds.h"
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#include "thermal_debugfs.h"
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struct thermal_attr {
@@ -139,6 +140,7 @@ struct thermal_zone_device {
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#ifdef CONFIG_THERMAL_DEBUGFS
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struct thermal_debugfs *debugfs;
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#endif
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struct list_head user_thresholds;
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struct thermal_trip_desc trips[] __counted_by(num_trips);
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};
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‎drivers/thermal/thermal_thresholds.c‎

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@@ -0,0 +1,229 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright 2024 Linaro Limited
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*
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* Author: Daniel Lezcano <[email protected]>
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*
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* Thermal thresholds
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*/
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#include <linux/list.h>
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#include <linux/list_sort.h>
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#include <linux/slab.h>
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#include "thermal_core.h"
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#include "thermal_thresholds.h"
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int thermal_thresholds_init(struct thermal_zone_device *tz)
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{
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INIT_LIST_HEAD(&tz->user_thresholds);
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return 0;
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}
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void thermal_thresholds_flush(struct thermal_zone_device *tz)
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{
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struct list_head *thresholds = &tz->user_thresholds;
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struct user_threshold *entry, *tmp;
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lockdep_assert_held(&tz->lock);
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list_for_each_entry_safe(entry, tmp, thresholds, list_node) {
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list_del(&entry->list_node);
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kfree(entry);
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}
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__thermal_zone_device_update(tz, THERMAL_TZ_FLUSH_THRESHOLDS);
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}
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void thermal_thresholds_exit(struct thermal_zone_device *tz)
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{
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thermal_thresholds_flush(tz);
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}
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static int __thermal_thresholds_cmp(void *data,
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const struct list_head *l1,
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const struct list_head *l2)
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{
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struct user_threshold *t1 = container_of(l1, struct user_threshold, list_node);
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struct user_threshold *t2 = container_of(l2, struct user_threshold, list_node);
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return t1->temperature - t2->temperature;
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}
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static struct user_threshold *__thermal_thresholds_find(const struct list_head *thresholds,
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int temperature)
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{
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struct user_threshold *t;
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list_for_each_entry(t, thresholds, list_node)
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if (t->temperature == temperature)
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return t;
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return NULL;
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}
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static bool __thermal_threshold_is_crossed(struct user_threshold *threshold, int temperature,
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int last_temperature, int direction,
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int *low, int *high)
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{
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if (temperature >= threshold->temperature) {
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if (threshold->temperature > *low &&
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THERMAL_THRESHOLD_WAY_DOWN & threshold->direction)
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*low = threshold->temperature;
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if (last_temperature < threshold->temperature &&
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threshold->direction & direction)
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return true;
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} else {
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if (threshold->temperature < *high && THERMAL_THRESHOLD_WAY_UP
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& threshold->direction)
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*high = threshold->temperature;
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if (last_temperature >= threshold->temperature &&
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threshold->direction & direction)
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return true;
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}
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return false;
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}
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static bool thermal_thresholds_handle_raising(struct list_head *thresholds, int temperature,
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int last_temperature, int *low, int *high)
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{
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struct user_threshold *t;
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list_for_each_entry(t, thresholds, list_node) {
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if (__thermal_threshold_is_crossed(t, temperature, last_temperature,
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THERMAL_THRESHOLD_WAY_UP, low, high))
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return true;
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}
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return false;
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}
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static bool thermal_thresholds_handle_dropping(struct list_head *thresholds, int temperature,
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int last_temperature, int *low, int *high)
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{
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struct user_threshold *t;
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list_for_each_entry_reverse(t, thresholds, list_node) {
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if (__thermal_threshold_is_crossed(t, temperature, last_temperature,
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THERMAL_THRESHOLD_WAY_DOWN, low, high))
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return true;
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}
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return false;
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}
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void thermal_thresholds_handle(struct thermal_zone_device *tz, int *low, int *high)
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{
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struct list_head *thresholds = &tz->user_thresholds;
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int temperature = tz->temperature;
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int last_temperature = tz->last_temperature;
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bool notify;
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lockdep_assert_held(&tz->lock);
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/*
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* We need a second update in order to detect a threshold being crossed
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*/
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if (last_temperature == THERMAL_TEMP_INVALID)
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return;
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/*
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* The temperature is stable, so obviously we can not have
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* crossed a threshold.
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*/
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if (last_temperature == temperature)
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return;
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/*
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* Since last update the temperature:
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* - increased : thresholds are crossed the way up
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* - decreased : thresholds are crossed the way down
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*/
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if (temperature > last_temperature)
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notify = thermal_thresholds_handle_raising(thresholds, temperature,
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last_temperature, low, high);
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else
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notify = thermal_thresholds_handle_dropping(thresholds, temperature,
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last_temperature, low, high);
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if (notify)
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pr_debug("A threshold has been crossed the way %s, with a temperature=%d, last_temperature=%d\n",
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temperature > last_temperature ? "up" : "down", temperature, last_temperature);
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}
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int thermal_thresholds_add(struct thermal_zone_device *tz, int temperature, int direction)
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{
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struct list_head *thresholds = &tz->user_thresholds;
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struct user_threshold *t;
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lockdep_assert_held(&tz->lock);
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t = __thermal_thresholds_find(thresholds, temperature);
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if (t) {
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if (t->direction == direction)
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return -EEXIST;
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t->direction |= direction;
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} else {
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t = kmalloc(sizeof(*t), GFP_KERNEL);
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if (!t)
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return -ENOMEM;
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INIT_LIST_HEAD(&t->list_node);
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t->temperature = temperature;
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t->direction = direction;
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list_add(&t->list_node, thresholds);
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list_sort(NULL, thresholds, __thermal_thresholds_cmp);
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}
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__thermal_zone_device_update(tz, THERMAL_TZ_ADD_THRESHOLD);
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return 0;
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}
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int thermal_thresholds_delete(struct thermal_zone_device *tz, int temperature, int direction)
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{
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struct list_head *thresholds = &tz->user_thresholds;
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struct user_threshold *t;
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lockdep_assert_held(&tz->lock);
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t = __thermal_thresholds_find(thresholds, temperature);
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if (!t)
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return -ENOENT;
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if (t->direction == direction) {
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list_del(&t->list_node);
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kfree(t);
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} else {
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t->direction &= ~direction;
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}
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__thermal_zone_device_update(tz, THERMAL_TZ_DEL_THRESHOLD);
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return 0;
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}
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int thermal_thresholds_for_each(struct thermal_zone_device *tz,
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int (*cb)(struct user_threshold *, void *arg), void *arg)
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{
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struct list_head *thresholds = &tz->user_thresholds;
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struct user_threshold *entry;
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int ret;
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lockdep_assert_held(&tz->lock);
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list_for_each_entry(entry, thresholds, list_node) {
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ret = cb(entry, arg);
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if (ret)
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return ret;
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}
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return 0;
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}

‎drivers/thermal/thermal_thresholds.h‎

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@@ -0,0 +1,19 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __THERMAL_THRESHOLDS_H__
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#define __THERMAL_THRESHOLDS_H__
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struct user_threshold {
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struct list_head list_node;
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int temperature;
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int direction;
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};
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int thermal_thresholds_init(struct thermal_zone_device *tz);
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void thermal_thresholds_exit(struct thermal_zone_device *tz);
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void thermal_thresholds_flush(struct thermal_zone_device *tz);
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void thermal_thresholds_handle(struct thermal_zone_device *tz, int *low, int *high);
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int thermal_thresholds_add(struct thermal_zone_device *tz, int temperature, int direction);
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int thermal_thresholds_delete(struct thermal_zone_device *tz, int temperature, int direction);
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int thermal_thresholds_for_each(struct thermal_zone_device *tz,
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int (*cb)(struct user_threshold *, void *arg), void *arg);
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#endif

‎include/linux/thermal.h‎

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@@ -56,6 +56,9 @@ enum thermal_notify_event {
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THERMAL_TZ_UNBIND_CDEV, /* Cooling dev is unbind from the thermal zone */
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THERMAL_INSTANCE_WEIGHT_CHANGED, /* Thermal instance weight changed */
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THERMAL_TZ_RESUME, /* Thermal zone is resuming after system sleep */
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THERMAL_TZ_ADD_THRESHOLD, /* Threshold added */
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THERMAL_TZ_DEL_THRESHOLD, /* Threshold deleted */
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THERMAL_TZ_FLUSH_THRESHOLDS, /* All thresholds deleted */
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};
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/**

‎include/uapi/linux/thermal.h‎

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@@ -3,6 +3,8 @@
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#define _UAPI_LINUX_THERMAL_H
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#define THERMAL_NAME_LENGTH 20
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#define THERMAL_THRESHOLD_WAY_UP BIT(0)
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#define THERMAL_THRESHOLD_WAY_DOWN BIT(1)
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enum thermal_device_mode {
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THERMAL_DEVICE_DISABLED = 0,

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