linux-kernel - Re: [PATCH v5 1/2] iio:temperature:max31856:Add device tree bind info

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Date:   Thu, 28 Feb 2019 16:15:55 +0100
From:   Patrick Havelange <patrick.havelange@...ensium.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Mark Rutland <mark.rutland@....com>,
        Paresh Chaudhary <paresh.chaudhary@...kwellcollins.com>,
        Matt Weber <matthew.weber@...kwellcollins.com>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v5 1/2] iio:temperature:max31856:Add device tree bind info

On Thu, Feb 28, 2019 at 12:59 AM Rob Herring <robh@...nel.org> wrote:
>
> On Tue, Feb 26, 2019 at 04:02:13PM +0100, Patrick Havelange wrote:
> > From: Paresh Chaudhary <paresh.chaudhary@...kwellcollins.com>
> >
> > This patch added device tree binding info for MAX31856 driver.
> >
> > Signed-off-by: Paresh Chaudhary <paresh.chaudhary@...kwellcollins.com>
> > Signed-off-by: Matt Weber <matthew.weber@...kwellcollins.com>
> > Signed-off-by: Patrick Havelange <patrick.havelange@...ensium.com>
> > ---
> > Changes
> > v1 -> v2
> > [Matt
> >  - Removed comment block and added possibilities of
> >    thermocouple type in device tree binding doc.
> >
> > v2 -> v3
> >  - Rebased
> >
> > v3 -> v4
> >  - Removed one-shot property related information.
> >  - Used standard name 'temp-sensor'
> >
> > v4 -> v5
> > [Patrick
> >  - Rename thermocouple type to maxim,thermocouple-type for DT entry
> > ---
> >  .../bindings/iio/temperature/max31856.txt     | 29 +++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/temperature/max31856.txt
> >
> > diff --git a/Documentation/devicetree/bindings/iio/temperature/max31856.txt b/Documentation/devicetree/bindings/iio/temperature/max31856.txt
> > new file mode 100644
> > index 000000000000..b4396069b8fa
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/temperature/max31856.txt
> > @@ -0,0 +1,29 @@
> > +Maxim MAX31856 thermocouple support
> > +
> > +https://datasheets.maximintegrated.com/en/ds/MAX31856.pdf
> > +
> > +Required properties:
> > +     - compatible: must be "maxim,max31856"
> > +     - reg: SPI chip select number for the device
> > +     - spi-max-frequency: As per datasheet max. supported freq is 5000000
> > +     - spi-cpha: must be defined for max31856 to enable SPI mode 1
> > +     - maxim,thermocouple-type: Type of thermocouple (By default is K-Type)
> > +             0x00 : TYPE_B
> > +             0x01 : TYPE_E
> > +             0x02 : TYPE_J
> > +             0x03 : TYPE_K (default)
> > +             0x04 : TYPE_N
> > +             0x05 : TYPE_R
> > +             0x06 : TYPE_S
> > +             0x07 : TYPE_T
>
> These appear to be standard types. Perhaps this should be a common
> property instead?

A remark on the v4 of the patch recommended to add a vendor prefix. It
also mentioned that it could be done as a generic type with a
translation layer for each driver.
Maybe this generic type could be introduced in a separate patch, or
when another driver also uses that kind of thermocouple-type, as there
is no other use of it for the moment it seems.


>
> > +
> > +     Refer to spi/spi-bus.txt for generic SPI slave bindings.
> > +
> > + Example:
> > +     temp-sensor@0 {
> > +             compatible = "maxim,max31856";
> > +             reg = <0>;
> > +             spi-max-frequency = <5000000>;
> > +             spi-cpha;
> > +             maxim,thermocouple-type = <0x03>;
> > +     };
> > --
> > 2.19.1
> >