This patch adds a simple step_wise governor to the
generic thermal layer. This algorithm throttles the
cooling devices in a linear fashion. If the 'trend'
is heating, it throttles by one step. And if the
thermal trend is cooling it de-throttles by one step.
This actually moves the throttling logic from thermal_sys.c
and puts inside step_wise.c, without any change.
Signed-off-by: Durgadoss R <durgadoss.r@xxxxxxxxx>
---
drivers/thermal/Kconfig | 6 ++
drivers/thermal/Makefile | 1 +
drivers/thermal/step_wise.c | 204 +++++++++++++++++++++++++++++++++++++++++++
include/linux/thermal.h | 9 ++
4 files changed, 220 insertions(+)
create mode 100644 drivers/thermal/step_wise.c
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index f5110c0..0401cdf 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -33,3 +33,9 @@ config FAIR_SHARE
depends on THERMAL
help
Enable this to manage platform thermals using fair-share governor.
+
+config STEP_WISE
+ bool "Step_wise thermal governor"
+ depends on THERMAL
+ help
+ Enable this to manage platform thermals using a simple linear
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 4ffe1a8..c2c0ce0 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -5,3 +5,4 @@
obj-$(CONFIG_THERMAL) += thermal_sys.o
obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o
obj-$(CONFIG_FAIR_SHARE) += fair_share.o
+obj-$(CONFIG_STEP_WISE) += step_wise.o
diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
new file mode 100644
index 0000000..0456b38
--- /dev/null
+++ b/drivers/thermal/step_wise.c
@@ -0,0 +1,204 @@
+/*
+ * step_wise.c - A step-by-step Thermal throttling governor
+ *
+ * Copyright (C) 2012 Intel Corp
+ * Copyright (C) 2012 Durgadoss R <durgadoss.r@xxxxxxxxx>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * 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.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/thermal.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 lower cooling
+ * state for this trip point
+ */
+static unsigned long get_target_state(struct thermal_instance *instance,
+ enum thermal_trend trend)
+{
+ struct thermal_cooling_device *cdev = instance->cdev;
+ unsigned long cur_state;
+
+ cdev->ops->get_cur_state(cdev, &cur_state);
+
+ if (trend == THERMAL_TREND_RAISING) {
+ cur_state = cur_state < instance->upper ?
+ (cur_state + 1) : instance->upper;
+ } else if (trend == THERMAL_TREND_DROPPING) {
+ cur_state = cur_state > instance->lower ?
+ (cur_state - 1) : instance->lower;
+ }
+
+ return cur_state;
+}
+
+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 update_instance_for_throttle(struct thermal_zone_device *tz,
+ int trip, enum thermal_trip_type trip_type,
+ enum thermal_trend trend)
+{
+ struct thermal_instance *instance;
+
+ list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+ if (instance->trip != trip)
+ continue;
+
+ instance->target = get_target_state(instance, trend);
+
+ /* Activate a passive thermal instance */
+ if (instance->target == THERMAL_NO_TARGET)
+ update_passive_instance(tz, trip_type, 1);
+
+ instance->cdev->updated = false; /* cdev needs update */
+ }
+}
+
+static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
+ int trip, enum thermal_trip_type trip_type)
+{
+ struct thermal_instance *instance;
+ struct thermal_cooling_device *cdev;
+ unsigned long cur_state;
+
+ list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+ if (instance->trip != trip ||
+ instance->target == THERMAL_NO_TARGET)
+ continue;
+
+ cdev = instance->cdev;
+ cdev->ops->get_cur_state(cdev, &cur_state);
+
+ instance->target = cur_state > instance->lower ?
+ (cur_state - 1) : THERMAL_NO_TARGET;
+
+ /* Deactivate a passive thermal instance */
+ if (instance->target == THERMAL_NO_TARGET)
+ update_passive_instance(tz, trip_type, -1);
+
+ cdev->updated = false; /* cdev needs update */
+ }
+}
+
+static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
+{
+ long trip_temp;
+ enum thermal_trip_type trip_type;
+ enum thermal_trend trend;
+
+ 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);
+
+ mutex_lock(&tz->lock);
+
+ if (tz->temperature >= trip_temp)
+ update_instance_for_throttle(tz, trip, trip_type, trend);
+ else
+ update_instance_for_dethrottle(tz, trip, trip_type);
+
+ mutex_unlock(&tz->lock);
+}
+
+/**
+ * thermal_cdev_update - Updates the throttle state for the given cdev
+ * @cdev - cooling device, for which the throttle state is to be set
+ *
+ * This function loops through all the instances for the given cdev,
+ * to find out the maximum throttle state; and sets the cur_state of
+ * the cdev to that value.
+ */
+static void thermal_cdev_update(struct thermal_cooling_device *cdev)
+{
+ struct thermal_instance *instance;
+ unsigned long target = 0;
+
+ /* cdev is already updated */
+ if (cdev->updated)
+ return;
+
+ mutex_lock(&cdev->lock);
+
+ /* Make sure cdev enters the deepest cooling state */
+ list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
+ if (instance->target == THERMAL_NO_TARGET)
+ continue;
+ if (instance->target > target)
+ target = instance->target;
+ }
+
+ mutex_unlock(&cdev->lock);
+
+ cdev->ops->set_cur_state(cdev, target);
+ cdev->updated = true;
+}
+
+/**
+ * step_wise_throttle - throttles devices asscciated with the given zone
+ * @tz - thermal_zone_device
+ * @trip - the trip point
+ * @trip_type - type of the trip point
+ *
+ * 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.
+ */
+void 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);
+}
+EXPORT_SYMBOL(step_wise_throttle);
+
+MODULE_AUTHOR("Durgadoss R");
+MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 4e2dc2c..60d2743 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -266,6 +266,15 @@ static inline void fair_share_throttle(struct thermal_zone_device *tz, int trip)
}
#endif
+#ifdef CONFIG_STEP_WISE
+extern void step_wise_throttle(struct thermal_zone_device *tz, int trip);
+#else
+static inline void step_wise_throttle(struct thermal_zone_device *tz, int trip)
+{
+ return;
+}
+#endif
+
#ifdef CONFIG_NET
extern int thermal_generate_netlink_event(u32 orig, enum events event);
#else
--
1.7.9.5
--
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