path: root/Documentation/thermal
diff options
authorDurgadoss R <durgadoss.r@intel.com>2012-09-18 11:05:06 +0530
committerZhang Rui <rui.zhang@intel.com>2012-11-05 14:00:09 +0800
commit6ea083b18d39b35730e59587128cfd6f68bd30bc (patch)
tree8837fd244e6bde92938eb10e94351d6ccd40c4a9 /Documentation/thermal
parentf2b4caafd4aa64c9438b0a94af78b127228e6905 (diff)
Thermal: Add documentation for platform layer data
This patch adds documentation for thermal_bind_params and thermal_zone_params structures. Also, adds details on EXPORT_SYMBOL APIs. Signed-off-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Diffstat (limited to 'Documentation/thermal')
1 files changed, 64 insertions, 0 deletions
diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index ca1a1a34970e..88c02334e356 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -112,6 +112,29 @@ temperature) and throttle appropriate devices.
trip: indicates which trip point the cooling devices is associated with
in this thermal zone.
+1.4 Thermal Zone Parameters
+1.4.1 struct thermal_bind_params
+ This structure defines the following parameters that are used to bind
+ a zone with a cooling device for a particular trip point.
+ .cdev: The cooling device pointer
+ .weight: The 'influence' of a particular cooling device on this zone.
+ This is on a percentage scale. The sum of all these weights
+ (for a particular zone) cannot exceed 100.
+ .trip_mask:This is a bit mask that gives the binding relation between
+ this thermal zone and cdev, for a particular trip point.
+ If nth bit is set, then the cdev and thermal zone are bound
+ for trip point n.
+ .match: This call back returns success(0) if the 'tz and cdev' need to
+ be bound, as per platform data.
+1.4.2 struct thermal_zone_params
+ This structure defines the platform level parameters for a thermal zone.
+ This data, for each thermal zone should come from the platform layer.
+ This is an optional feature where some platforms can choose not to
+ provide this data.
+ .governor_name: Name of the thermal governor used for this zone
+ .num_tbps: Number of thermal_bind_params entries for this zone
+ .tbp: thermal_bind_params entries
2. sysfs attributes structure
RO read only value
@@ -126,6 +149,7 @@ Thermal zone device sys I/F, created once it's registered:
|---type: Type of the thermal zone
|---temp: Current temperature
|---mode: Working mode of the thermal zone
+ |---policy: Thermal governor used for this zone
|---trip_point_[0-*]_temp: Trip point temperature
|---trip_point_[0-*]_type: Trip point type
|---trip_point_[0-*]_hyst: Hysteresis value for this trip point
@@ -187,6 +211,10 @@ mode
charge of the thermal management.
RW, Optional
+ One of the various thermal governors used for a particular zone.
+ RW, Required
The temperature above which trip point will be fired.
Unit: millidegree Celsius
@@ -264,6 +292,7 @@ method, the sys I/F structure will be built like this:
|---type: acpitz
|---temp: 37000
|---mode: enabled
+ |---policy: step_wise
|---trip_point_0_temp: 100000
|---trip_point_0_type: critical
|---trip_point_1_temp: 80000
@@ -305,3 +334,38 @@ to a thermal_zone_device when it registers itself with the framework. The
THERMAL_DEV_FAULT}. Notification can be sent when the current temperature
crosses any of the configured thresholds.
+5. Export Symbol APIs:
+5.1: get_tz_trend:
+This function returns the trend of a thermal zone, i.e the rate of change
+of temperature of the thermal zone. Ideally, the thermal sensor drivers
+are supposed to implement the callback. If they don't, the thermal
+framework calculated the trend by comparing the previous and the current
+temperature values.
+This function returns the thermal_instance corresponding to a given
+{thermal_zone, cooling_device, trip_point} combination. Returns NULL
+if such an instance does not exist.
+This function handles the trip events from sensor drivers. It starts
+throttling the cooling devices according to the policy configured.
+For CRITICAL and HOT trip points, this notifies the respective drivers,
+and does actual throttling for other trip points i.e ACTIVE and PASSIVE.
+The throttling policy is based on the configured platform data; if no
+platform data is provided, this uses the step_wise throttling policy.
+This function serves as an arbitrator to set the state of a cooling
+device. It sets the cooling device to the deepest cooling state if
+This function lets the various thermal governors to register themselves
+with the Thermal framework. At run time, depending on a zone's platform
+data, a particular governor is used for throttling.
+This function unregisters a governor from the thermal framework.

Privacy Policy