Commit 9d0be7f4 authored by Eduardo Valentin's avatar Eduardo Valentin
Browse files

thermal: support slope and offset coefficients 



It is common to have a linear extrapolation from
the current sensor readings and the actual temperature
value. This is specially the case when the sensor
is in use to extrapolate hotspots.

This patch adds slope and offset constants for
single sensor linear extrapolation equation. Because
the same sensor can be use in different locations,
from board to board, these constants are added
as part of thermal_zone_params.

The constants are available through sysfs.

It is up to the device driver to determine
the usage of these values.

Signed-off-by: default avatarEduardo Valentin <edubezval@gmail.com>
parent ea54cac9

Documentation/thermal/sysfs-api.txt

+16 −0
Original line number Diff line number Diff line
@@ -190,6 +190,8 @@ Thermal zone device sys I/F, created once it's registered: 
    |---k_i:                    PID's integral term in the power allocator gov

    |---k_d:                    PID's derivative term in the power allocator

    |---integral_cutoff:        Offset above which errors are accumulated

    |---slope:                  Slope constant applied as linear extrapolation

    |---offset:                 Offset constant applied as linear extrapolation



Thermal cooling device sys I/F, created once it's registered:

/sys/class/thermal/cooling_device[0-*]:
@@ -359,6 +361,20 @@ integral_cutoff 
	Documentation/thermal/power_allocator.txt

	RW, Optional



slope

	The slope constant used in a linear extrapolation model

	to determine a hotspot temperature based off the sensor's

	raw readings. It is up to the device driver to determine

	the usage of these values.

	RW, Optional



offset

	The offset constant used in a linear extrapolation model

	to determine a hotspot temperature based off the sensor's

	raw readings. It is up to the device driver to determine

	the usage of these values.

	RW, Optional



*****************************

* Cooling device attributes *

*****************************

drivers/thermal/thermal_core.c

+4 −0
Original line number Diff line number Diff line
@@ -944,6 +944,8 @@ create_s32_tzp_attr(k_pu); 
create_s32_tzp_attr(k_i);

create_s32_tzp_attr(k_d);

create_s32_tzp_attr(integral_cutoff);

create_s32_tzp_attr(slope);

create_s32_tzp_attr(offset);

#undef create_s32_tzp_attr



static struct device_attribute *dev_tzp_attrs[] = {
@@ -953,6 +955,8 @@ static struct device_attribute *dev_tzp_attrs[] = { 
	&dev_attr_k_i,

	&dev_attr_k_d,

	&dev_attr_integral_cutoff,

	&dev_attr_slope,

	&dev_attr_offset,

};



static int create_tzp_attrs(struct device *dev)

include/linux/thermal.h

+11 −0
Original line number Diff line number Diff line
@@ -302,6 +302,17 @@ struct thermal_zone_params { 


	/* threshold below which the error is no longer accumulated */

	s32 integral_cutoff;



	/*

	 * @slope:	slope of a linear temperature adjustment curve.

	 * 		Used by thermal zone drivers.

	 */

	int slope;

	/*

	 * @offset:	offset of a linear temperature adjustment curve.

	 * 		Used by thermal zone drivers (default 0).

	 */

	int offset;

};



struct thermal_genl_event {

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