1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/thermal/gov_step_wise.c b/drivers/thermal/gov_step_wise.c
new file mode 100644
index 000000000000..ea277c466d8d
--- /dev/null
+++ b/drivers/thermal/gov_step_wise.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  step_wise.c - A step-by-step Thermal throttling governor
+ *
+ *  Copyright (C) 2012 Intel Corp
+ *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
+ *
+ *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/thermal.h>
+#include <linux/minmax.h>
+#include "thermal_trace.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, use a lower cooling state
+ *       for this trip point, but keep the cooling state above the applicable
+ *       minimum
+ * 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 the minimum applicable
+ *       cooling state for this trip point, or 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;
+
+	/*
+	 * 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);
+	dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
+
+	if (!instance->initialized) {
+		if (throttle)
+			return clamp(cur_state + 1, instance->lower, instance->upper);
+
+		return THERMAL_NO_TARGET;
+	}
+
+	if (throttle) {
+		if (trend == THERMAL_TREND_RAISING)
+			return clamp(cur_state + 1, instance->lower, instance->upper);
+
+		/*
+		 * If the zone temperature is falling, the cooling level can
+		 * be reduced, but it should still be above the lower state of
+		 * the given thermal instance to pull the temperature further
+		 * down.
+		 */
+		if (trend == THERMAL_TREND_DROPPING)
+			return clamp(cur_state - 1,
+				     min(instance->lower + 1, instance->upper),
+				     instance->upper);
+	} else if (trend == THERMAL_TREND_DROPPING) {
+		if (cur_state <= instance->lower)
+			return THERMAL_NO_TARGET;
+
+		/*
+		 * If 'throttle' is false, no mitigation is necessary, so
+		 * request the lower state for this instance.
+		 */
+		return instance->lower;
+	}
+
+	return instance->target;
+}
+
+static void thermal_zone_trip_update(struct thermal_zone_device *tz,
+				     const struct thermal_trip_desc *td,
+				     int trip_threshold)
+{
+	bool throttle = tz->temperature >= trip_threshold;
+	const struct thermal_trip *trip = &td->trip;
+	enum thermal_trend trend = get_tz_trend(tz, trip);
+	int trip_id = thermal_zone_trip_id(tz, trip);
+	struct thermal_instance *instance;
+
+	if (throttle)
+		trace_thermal_zone_trip(tz, trip_id, trip->type);
+
+	dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
+		trip_id, trip->type, trip_threshold, trend, throttle);
+
+	list_for_each_entry(instance, &td->thermal_instances, trip_node) {
+		int old_target;
+
+		old_target = instance->target;
+		instance->target = get_target_state(instance, trend, throttle);
+
+		dev_dbg(&instance->cdev->device, "old_target=%d, target=%ld\n",
+			old_target, instance->target);
+
+		if (instance->initialized && old_target == instance->target)
+			continue;
+
+		instance->initialized = true;
+
+		scoped_guard(cooling_dev, instance->cdev) {
+			instance->cdev->updated = false; /* cdev needs update */
+		}
+	}
+}
+
+static void step_wise_manage(struct thermal_zone_device *tz)
+{
+	const struct thermal_trip_desc *td;
+	struct thermal_instance *instance;
+
+	lockdep_assert_held(&tz->lock);
+
+	/*
+	 * Throttling Logic: Use the trend of the thermal zone to throttle.
+	 * If the thermal zone is 'heating up', throttle all of the cooling
+	 * devices associated with each trip point by one step. If the zone
+	 * is 'cooling down', it brings back the performance of the devices
+	 * by one step.
+	 */
+	for_each_trip_desc(tz, td) {
+		const struct thermal_trip *trip = &td->trip;
+
+		if (trip->temperature == THERMAL_TEMP_INVALID ||
+		    trip->type == THERMAL_TRIP_CRITICAL ||
+		    trip->type == THERMAL_TRIP_HOT)
+			continue;
+
+		thermal_zone_trip_update(tz, td, td->threshold);
+	}
+
+	for_each_trip_desc(tz, td) {
+		list_for_each_entry(instance, &td->thermal_instances, trip_node)
+			thermal_cdev_update(instance->cdev);
+	}
+}
+
+static struct thermal_governor thermal_gov_step_wise = {
+	.name	= "step_wise",
+	.manage	= step_wise_manage,
+};
+THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);