This patch introduces a simple 'weight' based
governor named fair-share governor. Whenever the
thermal framework gets notified of the trip point
violation, this governor (if configured), throttles
the cooling devices associated with a thermal zone.
This mapping between a thermal zone and a cooling device
and the effectiveness of cooling are provided in the
platform layer.
Signed-off-by: Durgadoss R <durgadoss.r@xxxxxxxxx>
---
drivers/thermal/Kconfig | 6 ++
drivers/thermal/Makefile | 3 +-
drivers/thermal/fair_share.c | 111 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 119 insertions(+), 1 deletions(-)
create mode 100644 drivers/thermal/fair_share.c
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 514a691..f5132f3 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -26,3 +26,9 @@ config SPEAR_THERMAL
help
Enable this to plug the SPEAr thermal sensor driver into the Linux
thermal framework
+
+config FAIR_SHARE
+ bool "Fair-share thermal governor"
+ depends on THERMAL
+ help
+ Enable this to manage platform thermals using fair-share governor.
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index a9fff0b..4ffe1a8 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -3,4 +3,5 @@
#
obj-$(CONFIG_THERMAL) += thermal_sys.o
-obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o
\ No newline at end of file
+obj-$(CONFIG_SPEAR_THERMAL) += spear_thermal.o
+obj-$(CONFIG_FAIR_SHARE) += fair_share.o
diff --git a/drivers/thermal/fair_share.c b/drivers/thermal/fair_share.c
new file mode 100644
index 0000000..59af81d
--- /dev/null
+++ b/drivers/thermal/fair_share.c
@@ -0,0 +1,111 @@
+/*
+ * fair_share.c - A simple weight based Thermal 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>
+
+/**
+ * get_trip_level: - obtains the current trip level for a zone
+ * @tz: thermal zone device
+ */
+int get_trip_level(struct thermal_zone_device *tz)
+{
+ int count = 0;
+ unsigned long cur_temp, trip_temp;
+
+ if (tz->trips == 0 || !tz->ops->get_trip_temp)
+ return 0;
+
+ tz->ops->get_temp(tz, &cur_temp);
+
+ for (count = 0; count < tz->trips; count++) {
+ tz->ops->get_trip_temp(tz, count, &trip_temp);
+ if (cur_temp < trip_temp)
+ break;
+ }
+ return count;
+}
+
+/**
+ * fair_share_throttle - throttles devices asscciated with the given zone
+ * @tz - thermal_zone_device
+ *
+ * Throttling Logic: This uses three parameters to calculate the new
+ * throttle state of the cooling devices associated with the given zone.
+ *
+ * P1. max_state: Maximum throttle state exposed by the cooling device.
+ * P2. weight[i]/100:
+ * How 'effective' the 'i'th device is, in cooling the given zone.
+ * P3. cur_trip_level/max_no_of_trips:
+ * This describes the extent to which the devices should be throttled.
+ * We do not want to throttle too much when we trip a lower temperature,
+ * whereas the throttling is at full swing if we trip critical levels.
+ * (Heavily assumes the trip points are in ascending order)
+ * new_state of cooling device = P3 * P2 * P1
+ */
+int fair_share_throttle(struct thermal_zone_device *tz)
+{
+ struct thermal_zone_params *tzp;
+ struct thermal_cooling_device *cdev;
+ unsigned long max_state, new_state;
+ int i;
+
+ int cur_trip_level = get_trip_level(tz);
+
+ /* Do not throttle:
+ * if there are no parameters defined for this zone
+ * if current trip level is 0 (for performance reasons)
+ */
+ if (!tz->tzp || cur_trip_level == 0)
+ return 0;
+
+ tzp = tz->tzp;
+
+ for (i = 0; i < tzp->num_cdevs; i++) {
+ /*
+ * Do not throttle:
+ * if this device cannot cool the zone, or
+ * if the cooling device does not exist anymore
+ */
+ if (tzp->weights[i] == 0 || !tzp->cdevs[i])
+ continue;
+
+ cdev = tzp->cdevs[i];
+ cdev->ops->get_max_state(cdev, &max_state);
+
+ new_state =
+ (long)(tzp->weights[i] * cur_trip_level * max_state) /
+ (100 * tz->trips);
+
+ cdev->ops->set_cur_state(cdev, new_state);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(fair_share_throttle);
+
+MODULE_AUTHOR("Durgadoss R");
+MODULE_DESCRIPTION("A simple weight based thermal throttling governor");
+MODULE_LICENSE("GPL");
--
1.7.0.4
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