Re: [PATCH V2 1/2] thermal: generic-adc: Add DT binding for ADC based thermal sensor

Rob Herring
2016-04-13T15:06:41Z

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";