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-rw-r--r--Documentation/thermal/sysfs-api.txt103
1 files changed, 91 insertions, 12 deletions
diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 1733ab947a9..88c02334e35 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -32,7 +32,8 @@ temperature) and throttle appropriate devices.
1.1 thermal zone device interface
1.1.1 struct thermal_zone_device *thermal_zone_device_register(char *name,
- int trips, void *devdata, struct thermal_zone_device_ops *ops)
+ int trips, int mask, void *devdata,
+ struct thermal_zone_device_ops *ops)
This interface function adds a new thermal zone device (sensor) to
/sys/class/thermal folder as thermal_zone[0-*]. It tries to bind all the
@@ -40,16 +41,17 @@ temperature) and throttle appropriate devices.
name: the thermal zone name.
trips: the total number of trip points this thermal zone supports.
+ mask: Bit string: If 'n'th bit is set, then trip point 'n' is writeable.
devdata: device private data
ops: thermal zone device call-backs.
.bind: bind the thermal zone device with a thermal cooling device.
.unbind: unbind the thermal zone device with a thermal cooling device.
.get_temp: get the current temperature of the thermal zone.
- .get_mode: get the current mode (user/kernel) of the thermal zone.
- - "kernel" means thermal management is done in kernel.
- - "user" will prevent kernel thermal driver actions upon trip points
+ .get_mode: get the current mode (enabled/disabled) of the thermal zone.
+ - "enabled" means the kernel thermal management is enabled.
+ - "disabled" will prevent kernel thermal driver action upon trip points
so that user applications can take charge of thermal management.
- .set_mode: set the mode (user/kernel) of the thermal zone.
+ .set_mode: set the mode (enabled/disabled) of the thermal zone.
.get_trip_type: get the type of certain trip point.
.get_trip_temp: get the temperature above which the certain trip point
will be fired.
@@ -82,7 +84,8 @@ temperature) and throttle appropriate devices.
1.3 interface for binding a thermal zone device with a thermal cooling device
1.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
- int trip, struct thermal_cooling_device *cdev);
+ int trip, struct thermal_cooling_device *cdev,
+ unsigned long upper, unsigned long lower);
This interface function bind a thermal cooling device to the certain trip
point of a thermal zone device.
@@ -91,6 +94,12 @@ temperature) and throttle appropriate devices.
cdev: thermal cooling device
trip: indicates which trip point the cooling devices is associated with
in this thermal zone.
+ upper:the Maximum cooling state for this trip point.
+ THERMAL_NO_LIMIT means no upper limit,
+ and the cooling device can be in max_state.
+ lower:the Minimum cooling state can be used for this trip point.
+ THERMAL_NO_LIMIT means no lower limit,
+ and the cooling device can be in cooling state 0.
1.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
int trip, struct thermal_cooling_device *cdev);
@@ -103,6 +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
@@ -117,8 +149,10 @@ 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
Thermal cooling device sys I/F, created once it's registered:
/sys/class/thermal/cooling_device[0-*]:
@@ -167,16 +201,20 @@ temp
RO, Required
mode
- One of the predefined values in [kernel, user].
+ One of the predefined values in [enabled, disabled].
This file gives information about the algorithm that is currently
managing the thermal zone. It can be either default kernel based
algorithm or user space application.
- kernel = Thermal management in kernel thermal zone driver.
- user = Preventing kernel thermal zone driver actions upon
- trip points so that user application can take full
- charge of the thermal management.
+ enabled = enable Kernel Thermal management.
+ disabled = Preventing kernel thermal zone driver actions upon
+ trip points so that user application can take full
+ charge of the thermal management.
RW, Optional
+policy
+ One of the various thermal governors used for a particular zone.
+ RW, Required
+
trip_point_[0-*]_temp
The temperature above which trip point will be fired.
Unit: millidegree Celsius
@@ -188,6 +226,11 @@ trip_point_[0-*]_type
thermal zone.
RO, Optional
+trip_point_[0-*]_hyst
+ The hysteresis value for a trip point, represented as an integer
+ Unit: Celsius
+ RW, Optional
+
cdev[0-*]
Sysfs link to the thermal cooling device node where the sys I/F
for cooling device throttling control represents.
@@ -248,7 +291,8 @@ method, the sys I/F structure will be built like this:
|thermal_zone1:
|---type: acpitz
|---temp: 37000
- |---mode: kernel
+ |---mode: enabled
+ |---policy: step_wise
|---trip_point_0_temp: 100000
|---trip_point_0_type: critical
|---trip_point_1_temp: 80000
@@ -290,3 +334,38 @@ to a thermal_zone_device when it registers itself with the framework. The
event will be one of:{THERMAL_AUX0, THERMAL_AUX1, THERMAL_CRITICAL,
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.
+
+5.2:get_thermal_instance:
+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.
+
+5.3:notify_thermal_framework:
+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.
+
+5.4:thermal_cdev_update:
+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
+possible.
+
+5.5:thermal_register_governor:
+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.
+
+5.6:thermal_unregister_governor:
+This function unregisters a governor from the thermal framework.