[RFC PATCH 11/12] thermal: introduce cooling state arbitrator

[Zhang Rui <rui.zhang@intel.com>]

Introduce simple arbitrator for setting device cooling state,
to fix the problem that a cooling device may be referenced by
by multiple trip points in multiple thermal zones.


With this patch, we have two stages for updating a thermal zone,
1. check if a thermal_instance needs to be updated or not
2. update the cooling device, based on the target cooling state
   of all its instances.

Note that, currently, the cooling device is set to the deepest
cooling state required.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
 drivers/thermal/thermal_sys.c |   41 ++++++++++++++++++++++++++++++++++++++---
 include/linux/thermal.h       |    1 +
 2 files changed, 39 insertions(+), 3 deletions(-)

Index: rtd3/drivers/thermal/thermal_sys.c
===================================================================
--- rtd3.orig/drivers/thermal/thermal_sys.c
+++ rtd3/drivers/thermal/thermal_sys.c
@@ -54,6 +54,7 @@ struct thermal_instance {
 	int trip;
 	unsigned long upper;	/* Highest cooling state for this trip point */
 	unsigned long lower;	/* Lowest cooling state for this trip point */
+	unsigned long target;	/* expected cooling state */
 	char attr_name[THERMAL_NAME_LENGTH];
 	struct device_attribute attr;
 	struct list_head tz_node; /* node in tz->instances */
@@ -812,6 +813,7 @@ int thermal_zone_bind_cooling_device(str
 	dev->trip = trip;
 	dev->upper = upper;
 	dev->lower = lower;
+	dev->target = -1;
 
 	result = get_idr(&tz->idr, &tz->lock, &dev->id);
 	if (result)
@@ -949,6 +951,7 @@ thermal_cooling_device_register(char *ty
 	strcpy(cdev->type, type);
 	INIT_LIST_HEAD(&cdev->instances);
 	cdev->ops = ops;
+	cdev->updated = 1;
 	cdev->device.class = &thermal_class;
 	cdev->devdata = devdata;
 	dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
@@ -1040,6 +1043,32 @@ void thermal_cooling_device_unregister(s
 }
 EXPORT_SYMBOL(thermal_cooling_device_unregister);
 
+static void thermal_zone_do_update(struct thermal_zone_device *tz)
+{
+	struct thermal_instance *instance1, *instance2;
+	struct thermal_cooling_device *cdev;
+	int target;
+
+	list_for_each_entry(instance1, &tz->instances, tz_node) {
+		cdev = instance1->cdev;
+
+		/* cooling device has already been updated*/
+		if (cdev->updated)
+			continue;
+
+		target = 0;
+		/* Make sure cdev enters the deepest cooling state */
+		list_for_each_entry(instance2, &cdev->instances, cdev_node) {
+			if (instance2->target == -1)
+				continue;
+			if (instance2->target > target)
+				target = instance2->target;
+		}
+		cdev->ops->set_cur_state(cdev, target);
+		cdev->updated = 1;
+	}
+}
+
 /*
  * Cooling algorithm for active trip points
  *
@@ -1086,19 +1115,24 @@ static void thermal_zone_trip_update(str
 				cur_state = cur_state > instance->lower ?
 				    (cur_state - 1) : instance->lower;
 			}
-			cdev->ops->set_cur_state(cdev, cur_state);
+			instance->target = cur_state;
+			cdev->updated = 0; /* cooling device needs update */
 		}
 	} else {	/* below trip */
 		list_for_each_entry(instance, &tz->instances, tz_node) {
 			if (instance->trip != trip)
 				continue;
 
+			/* Do not use the deacitve thermal instance */
+			if (instance->target == -1)
+				continue;
 			cdev = instance->cdev;
 			cdev->ops->get_cur_state(cdev, &cur_state);
 
 			cur_state = cur_state > instance->lower ?
-				    (cur_state - 1) : instance->lower;
-			cdev->ops->set_cur_state(cdev, cur_state);
+				    (cur_state - 1) : -1;
+			instance->target = cur_state;
+			cdev->updated = 0; /* cooling device needs update */
 		}
 	}
 
@@ -1159,6 +1193,7 @@ void thermal_zone_device_update(struct t
 		}
 	}
 
+	thermal_zone_do_update(tz);
 	if (tz->forced_passive)
 		thermal_zone_device_passive(tz, temp, tz->forced_passive,
 					    THERMAL_TRIPS_NONE);
Index: rtd3/include/linux/thermal.h
===================================================================
--- rtd3.orig/include/linux/thermal.h
+++ rtd3/include/linux/thermal.h
@@ -86,6 +86,7 @@ struct thermal_cooling_device {
 	struct device device;
 	void *devdata;
 	const struct thermal_cooling_device_ops *ops;
+	int updated; /* 1 if the cooling device does not need update */
 	struct list_head instances;
 	struct list_head node;
 };