Thermal: Introduce .get_trend() callback.

According to ACPI spec, tc1 and tc2 are used by OSPM
to anticipate the temperature trends.
We introduced the same concept to the generic thermal layer
for passive cooling, but now it seems that these values
are hard to be used on other platforms.

So We introduce .get_trend() as a more general solution.

For the platform thermal drivers that have their own way to
anticipate the temperature trends, they should provide
their own .get_trend() callback.
Or else, we will calculate the temperature trends by simply
comparing the current temperature and the cached previous
temperature reading.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Valentin, Eduardo <eduardo.valentin@ti.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
index b04fe2c4b0d5..146aa043f15b 100644
--- a/drivers/thermal/thermal_sys.c
+++ b/drivers/thermal/thermal_sys.c
@@ -723,6 +723,20 @@ static void thermal_zone_device_passive(struct thermal_zone_device *tz,
 	struct thermal_cooling_device *cdev;
 	long state, max_state;
 
+	if (!tz->ops->get_trend ||
+	    tz->ops->get_trend(tz, trip, (enum thermal_trend *)&trend)) {
+		/*
+		 * compare the current temperature and previous temperature
+		 * to get the thermal trend, if no special requirement
+		 */
+		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;
+	}
+
 	/*
 	 * Above Trip?
 	 * -----------
@@ -1091,6 +1105,9 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 		goto leave;
 	}
 
+	tz->last_temperature = tz->temperature;
+	tz->temperature = temp;
+
 	for (count = 0; count < tz->trips; count++) {
 		tz->ops->get_trip_type(tz, count, &trip_type);
 		tz->ops->get_trip_temp(tz, count, &trip_temp);
@@ -1150,8 +1167,6 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 		thermal_zone_device_passive(tz, temp, tz->forced_passive,
 					    THERMAL_TRIPS_NONE);
 
-	tz->last_temperature = temp;
-
 leave:
 	if (tz->passive)
 		thermal_zone_device_set_polling(tz, tz->passive_delay);