linux-kernel - [PATCH] thermal: tell cooling devices when a trip

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Date:	Wed, 30 Jul 2014 16:10:40 -0700
From:	Matt Longnecker <mlongnecker@...dia.com>
To:	Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<mlongnecker@...dia.com>
Subject: [PATCH] thermal: tell cooling devices when a trip_point changes

Some hardware can react autonomously at a programmed temperature.
For example, an SoC might implement a last ditch throttle or a
hardware thermal shutdown. The driver for such a device can
register itself as a cooling_device with the thermal framework.

With this change, the thermal framework notifies such a driver
when userspace alters the relevant trip temperature so that
the driver can reprogram its hardware

Signed-off-by: Matt Longnecker <mlongnecker@...dia.com>
---
 drivers/thermal/thermal_core.c |   30 ++++++++++++++++++++++++++++++
 include/linux/thermal.h        |    2 ++
 2 files changed, 32 insertions(+)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 71b0ec0..f25272e 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -597,6 +597,7 @@ trip_point_temp_store(struct device *dev, struct device_attribute *attr,
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
 	int trip, ret;
 	unsigned long temperature;
+	struct thermal_instance *pos = NULL;
 
 	if (!tz->ops->set_trip_temp)
 		return -EPERM;
@@ -609,6 +610,20 @@ trip_point_temp_store(struct device *dev, struct device_attribute *attr,
 
 	ret = tz->ops->set_trip_temp(tz, trip, temperature);
 
+	/*
+	 * Notify bound cooling devices that this trip point changed.
+	 * This is useful for cooling devices which represent a behavior
+	 * which trips in hardware (e.g. catastrophic shutdown)
+	 */
+	list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
+		if (pos->tz == tz && pos->trip == trip && pos->cdev) {
+			if (pos->cdev->ops->trip_point_changed)
+				pos->cdev->ops->trip_point_changed(pos->cdev,
+								   pos->tz,
+								   trip);
+		}
+	}
+
 	return ret ? ret : count;
 }
 
@@ -641,6 +656,7 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
 	int trip, ret;
 	unsigned long temperature;
+	struct thermal_instance *pos = NULL;
 
 	if (!tz->ops->set_trip_hyst)
 		return -EPERM;
@@ -658,6 +674,20 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
 	 */
 	ret = tz->ops->set_trip_hyst(tz, trip, temperature);
 
+	/*
+	 * Notify bound cooling devices that this trip point changed.
+	 * This is useful for cooling devices which represent a behavior
+	 * which trips in hardware (e.g. catastrophic shutdown)
+	 */
+	list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
+		if (pos->tz == tz && pos->trip == trip && pos->cdev) {
+			if (pos->cdev->ops->trip_point_changed)
+				pos->cdev->ops->trip_point_changed(pos->cdev,
+								   pos->tz,
+								   trip);
+		}
+	}
+
 	return ret ? ret : count;
 }
 
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index f7e11c7..7da7fc5 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -138,6 +138,8 @@ struct thermal_cooling_device_ops {
 	int (*get_max_state) (struct thermal_cooling_device *, unsigned long *);
 	int (*get_cur_state) (struct thermal_cooling_device *, unsigned long *);
 	int (*set_cur_state) (struct thermal_cooling_device *, unsigned long);
+	void (*trip_point_changed) (struct thermal_cooling_device *,
+				    struct thermal_zone_device *, int);
 };
 
 struct thermal_cooling_device {
-- 
1.7.9.5

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