1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index d7ef69d835f2..bb95709a6be8 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -706,6 +706,38 @@ static int thermal_get_crit_temp(struct thermal_zone_device *thermal,
                 return -EINVAL;
 }
 
+static int thermal_get_trend(struct thermal_zone_device *thermal,
+                                int trip, enum thermal_trend *trend)
+{
+        struct acpi_thermal *tz = thermal->devdata;
+        enum thermal_trip_type type;
+        int i;
+
+        if (thermal_get_trip_type(thermal, trip, &type))
+                return -EINVAL;
+
+        /* Only PASSIVE trip points need TREND */
+        if (type != THERMAL_TRIP_PASSIVE)
+                return -EINVAL;
+
+        /*
+         * tz->temperature has already been updated by generic thermal layer,
+         * before this callback being invoked
+         */
+        i = (tz->trips.passive.tc1 * (tz->temperature - tz->last_temperature))
+                + (tz->trips.passive.tc2
+                * (tz->temperature - tz->trips.passive.temperature));
+
+        if (i > 0)
+                *trend = THERMAL_TREND_RAISING;
+        else if (i < 0)
+                *trend = THERMAL_TREND_DROPPING;
+        else
+                *trend = THERMAL_TREND_STABLE;
+        return 0;
+}
+
+
 static int thermal_notify(struct thermal_zone_device *thermal, int trip,
                            enum thermal_trip_type trip_type)
 {
@@ -838,6 +870,7 @@ static const struct thermal_zone_device_ops acpi_thermal_zone_ops = {
         .get_trip_type = thermal_get_trip_type,
         .get_trip_temp = thermal_get_trip_temp,
         .get_crit_temp = thermal_get_crit_temp,
+        .get_trend = thermal_get_trend,
         .notify = thermal_notify,
 };