| Message ID | 1460382102-27755-1-git-send-email-ldewangan@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Eduardo Valentin |
| Headers | show |
On Mon, Apr 11, 2016 at 07:11:41PM +0530, Laxman Dewangan wrote: > Sometimes, thermal sensors like NCT thermistors are connected to > the ADC channel. The temperature is read by reading the voltage > across the sensor resistance via ADC and referring the lookup > table for ADC value to temperature. > > Add DT binding doc for the ADC based thermal sensor driver to > detail the DT property and provide the example for how to use it. > > Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> > > --- > Changes from V1: > - Make the lookup table to two dimensional instead of single array of linear > step of temperature. > - Remove detailing of IIO frameowrk and drivers. > - Added proper braces, indenting and labels. > > .../bindings/thermal/thermal-generic-adc.txt | 86 ++++++++++++++++++++++ > 1 file changed, 86 insertions(+) > create mode 100644 Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt > > diff --git a/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt > new file mode 100644 > index 0000000..c5c2e5b > --- /dev/null > +++ b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt > @@ -0,0 +1,86 @@ > +General Purpose Analog To Digital Converter (ADC) based thermal sensor. > + > +On some of platforms, thermal sensor like thermistors are connected to > +one of ADC channel and sensor resistance is read via voltage across the > +sensor resistor. The voltage read across the sensor is mapped to > +temperature using voltage-temperature lookup table. > + > +Required properties: > +=================== > +- compatible: Must be "generic-adc-thermal". > +- temperature-lookup-table: Two dimensional array of Integer; lookup table > + to map the relation between ADC value and > + temperature. When ADC is read, the value is > + looked up on the table to get the equivalent > + temperature. First value is ?, 2nd value is ? The units are milliCelsius? > +- #thermal-sensor-cells: Should be 1. See ./thermal.txt for a description > + of this property. > + > +Example : > +#include <dt-bindings/thermal/thermal.h> > + > +i2c@7000c400 { > + ads1015: ads1015@4a { > + reg = <0x4a>; > + compatible = "ads1015"; > + sampling-frequency = <3300>; > + #io-channel-cells = <1>; > + }; > +}; > + > +tboard_thermistor: thermal-sensor@1 { Drop the unit address. > + compatible = "generic-adc-thermal"; -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt new file mode 100644 index 0000000..c5c2e5b --- /dev/null +++ b/Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt @@ -0,0 +1,86 @@ +General Purpose Analog To Digital Converter (ADC) based thermal sensor. + +On some of platforms, thermal sensor like thermistors are connected to +one of ADC channel and sensor resistance is read via voltage across the +sensor resistor. The voltage read across the sensor is mapped to +temperature using voltage-temperature lookup table. + +Required properties: +=================== +- compatible: Must be "generic-adc-thermal". +- temperature-lookup-table: Two dimensional array of Integer; lookup table + to map the relation between ADC value and + temperature. When ADC is read, the value is + looked up on the table to get the equivalent + temperature. +- #thermal-sensor-cells: Should be 1. See ./thermal.txt for a description + of this property. + +Example : +#include <dt-bindings/thermal/thermal.h> + +i2c@7000c400 { + ads1015: ads1015@4a { + reg = <0x4a>; + compatible = "ads1015"; + sampling-frequency = <3300>; + #io-channel-cells = <1>; + }; +}; + +tboard_thermistor: thermal-sensor@1 { + compatible = "generic-adc-thermal"; + #thermal-sensor-cells = <0>; + io-channels = <&ads1015 1>; + io-channel-names = "sensor-channel"; + temperature-lookup-table = < (-40000) 2578 + (-39000) 2577 + (-38000) 2576 + (-37000) 2575 + (-36000) 2574 + (-35000) 2573 + (-34000) 2572 + (-33000) 2571 + (-32000) 2569 + (-31000) 2568 + (-30000) 2567 + :::::::::: + 118000 254 + 119000 247 + 120000 240 + 121000 233 + 122000 226 + 123000 220 + 124000 214 + 125000 208>; +}; + +dummy_cool_dev: dummy-cool-dev { + compatible = "dummy-cooling-dev"; + #cooling-cells = <2>; /* min followed by max */ +}; + +thermal-zones { + Tboard { + polling-delay = <15000>; /* milliseconds */ + polling-delay-passive = <0>; /* milliseconds */ + thermal-sensors = <&tboard_thermistor>; + + trips { + therm_est_trip: therm_est_trip { + temperature = <40000>; + type = "active"; + hysteresis = <1000>; + }; + }; + + cooling-maps { + map0 { + trip = <&therm_est_trip>; + cooling-device = <&dummy_cool_dev THERMAL_NO_LIMIT THERMAL_NO_LIMIT>; + contribution = <100>; + }; + + }; + }; +};
Sometimes, thermal sensors like NCT thermistors are connected to the ADC channel. The temperature is read by reading the voltage across the sensor resistance via ADC and referring the lookup table for ADC value to temperature. Add DT binding doc for the ADC based thermal sensor driver to detail the DT property and provide the example for how to use it. Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> --- Changes from V1: - Make the lookup table to two dimensional instead of single array of linear step of temperature. - Remove detailing of IIO frameowrk and drivers. - Added proper braces, indenting and labels. .../bindings/thermal/thermal-generic-adc.txt | 86 ++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 Documentation/devicetree/bindings/thermal/thermal-generic-adc.txt