1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
new file mode 100644
index 000000000..ee047ca43
--- /dev/null
+++ b/drivers/thermal/step_wise.c
@@ -0,0 +1,230 @@
+/*
+ *  step_wise.c - A step-by-step Thermal throttling governor
+ *
+ *  Copyright (C) 2012 Intel Corp
+ *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
+ *
+ *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/thermal.h>
+#include <trace/events/thermal.h>
+
+#include "thermal_core.h"
+
+/*
+ * If the temperature is higher than a trip point,
+ *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
+ *       state for this trip point
+ *    b. if the trend is THERMAL_TREND_DROPPING, do nothing
+ *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
+ *       for this trip point
+ *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
+ *       for this trip point
+ * If the temperature is lower than a trip point,
+ *    a. if the trend is THERMAL_TREND_RAISING, do nothing
+ *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
+ *       state for this trip point, if the cooling state already
+ *       equals lower limit, deactivate the thermal instance
+ *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
+ *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
+ *       if the cooling state already equals lower limit,
+ *       deactivate the thermal instance
+ */
+static unsigned long get_target_state(struct thermal_instance *instance,
+				enum thermal_trend trend, bool throttle)
+{
+	struct thermal_cooling_device *cdev = instance->cdev;
+	unsigned long cur_state;
+	unsigned long next_target;
+
+	/*
+	 * We keep this instance the way it is by default.
+	 * Otherwise, we use the current state of the
+	 * cdev in use to determine the next_target.
+	 */
+	cdev->ops->get_cur_state(cdev, &cur_state);
+	next_target = instance->target;
+	dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
+
+	if (!instance->initialized) {
+		if (throttle) {
+			next_target = (cur_state + 1) >= instance->upper ?
+					instance->upper :
+					((cur_state + 1) < instance->lower ?
+					instance->lower : (cur_state + 1));
+		} else {
+			next_target = THERMAL_NO_TARGET;
+		}
+
+		return next_target;
+	}
+
+	switch (trend) {
+	case THERMAL_TREND_RAISING:
+		if (throttle) {
+			next_target = cur_state < instance->upper ?
+				    (cur_state + 1) : instance->upper;
+			if (next_target < instance->lower)
+				next_target = instance->lower;
+		}
+		break;
+	case THERMAL_TREND_RAISE_FULL:
+		if (throttle)
+			next_target = instance->upper;
+		break;
+	case THERMAL_TREND_DROPPING:
+		if (cur_state <= instance->lower) {
+			if (!throttle)
+				next_target = THERMAL_NO_TARGET;
+		} else {
+			if (!throttle) {
+				next_target = cur_state - 1;
+				if (next_target > instance->upper)
+					next_target = instance->upper;
+			}
+		}
+		break;
+	case THERMAL_TREND_DROP_FULL:
+		if (cur_state == instance->lower) {
+			if (!throttle)
+				next_target = THERMAL_NO_TARGET;
+		} else
+			next_target = instance->lower;
+		break;
+	default:
+		break;
+	}
+
+	return next_target;
+}
+
+static void update_passive_instance(struct thermal_zone_device *tz,
+				enum thermal_trip_type type, int value)
+{
+	/*
+	 * If value is +1, activate a passive instance.
+	 * If value is -1, deactivate a passive instance.
+	 */
+	if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
+		tz->passive += value;
+}
+
+static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
+{
+	int trip_temp;
+	enum thermal_trip_type trip_type;
+	enum thermal_trend trend;
+	struct thermal_instance *instance;
+	bool throttle = false;
+	int old_target;
+
+	if (trip == THERMAL_TRIPS_NONE) {
+		trip_temp = tz->forced_passive;
+		trip_type = THERMAL_TRIPS_NONE;
+	} else {
+		tz->ops->get_trip_temp(tz, trip, &trip_temp);
+		tz->ops->get_trip_type(tz, trip, &trip_type);
+	}
+
+	trend = get_tz_trend(tz, trip);
+
+	if (tz->temperature >= trip_temp) {
+		throttle = true;
+		trace_thermal_zone_trip(tz, trip, trip_type);
+	}
+
+	dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
+				trip, trip_type, trip_temp, trend, throttle);
+
+	mutex_lock(&tz->lock);
+
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		if (instance->trip != trip)
+			continue;
+
+		old_target = instance->target;
+		instance->target = get_target_state(instance, trend, throttle);
+		dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
+					old_target, (int)instance->target);
+
+		if (instance->initialized && old_target == instance->target)
+			continue;
+
+		/* Activate a passive thermal instance */
+		if (old_target == THERMAL_NO_TARGET &&
+			instance->target != THERMAL_NO_TARGET)
+			update_passive_instance(tz, trip_type, 1);
+		/* Deactivate a passive thermal instance */
+		else if (old_target != THERMAL_NO_TARGET &&
+			instance->target == THERMAL_NO_TARGET)
+			update_passive_instance(tz, trip_type, -1);
+
+		instance->initialized = true;
+		mutex_lock(&instance->cdev->lock);
+		instance->cdev->updated = false; /* cdev needs update */
+		mutex_unlock(&instance->cdev->lock);
+	}
+
+	mutex_unlock(&tz->lock);
+}
+
+/**
+ * step_wise_throttle - throttles devices associated with the given zone
+ * @tz - thermal_zone_device
+ * @trip - trip point index
+ *
+ * Throttling Logic: This uses the trend of the thermal zone to throttle.
+ * If the thermal zone is 'heating up' this throttles all the cooling
+ * devices associated with the zone and its particular trip point, by one
+ * step. If the zone is 'cooling down' it brings back the performance of
+ * the devices by one step.
+ */
+static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
+{
+	struct thermal_instance *instance;
+
+	thermal_zone_trip_update(tz, trip);
+
+	if (tz->forced_passive)
+		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
+
+	mutex_lock(&tz->lock);
+
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
+		thermal_cdev_update(instance->cdev);
+
+	mutex_unlock(&tz->lock);
+
+	return 0;
+}
+
+static struct thermal_governor thermal_gov_step_wise = {
+	.name		= "step_wise",
+	.throttle	= step_wise_throttle,
+};
+
+int thermal_gov_step_wise_register(void)
+{
+	return thermal_register_governor(&thermal_gov_step_wise);
+}
+
+void thermal_gov_step_wise_unregister(void)
+{
+	thermal_unregister_governor(&thermal_gov_step_wise);
+}