Thermal framework today supports monitoring for rising temperatures and subsequently initiating cooling action in case of a trip point being crossed. There are scenarios where a SoC needs some warming action to be activated if the temperature falls below a cetain allowable limit. Since warming action can be considered mirror opposite of cooling action, most of the thermal framework can be re-used to achieve this.
To enable thermal framework to monitor falling temperature, a new parameter is added to the thermal trip point binding in the device tree to indicate the direction(rising/falling) of temperature monitoring. Thermal DT driver is extended to capture this information from the device tree entries and to reflect it in the thermal framework as a new enum variable in the thermal trip point structure. As an initial attempt, step-wise governor is extended to support bi-directional monitoring of temprature if a trip point is hit, depending on the newly introduced enum variable. Finally thermal sysfs entries are extended to indicate the trip point monitor direction. Patch series introducing various resources that are used as warming devices on Qualcomm sdm845: https://lkml.org/lkml/2019/7/29/749 (already merged) https://lkml.org/lkml/2019/9/10/727 (under review) Thara Gopinath (4): dt-bindings: thermal: Introduce monitor-falling binding to thermal trip point description thermal: Thermal core and sysfs changes needed to support bi-directional monitoring of trip points. thermal: of-thermal: Extend thermal dt driver to support bi-directional monitoring of a thermal trip point. thermal: step_wise: Extend thermal step-wise governor to monitor falling temperature. .../devicetree/bindings/thermal/thermal.txt | 8 +++ drivers/thermal/of-thermal.c | 22 ++++++++ drivers/thermal/step_wise.c | 59 +++++++++++++++------ drivers/thermal/thermal_sysfs.c | 60 ++++++++++++++++++++-- include/linux/thermal.h | 10 ++++ include/uapi/linux/thermal.h | 2 +- 6 files changed, 141 insertions(+), 20 deletions(-) -- 2.1.4
