linux-kernel - Re: [PATCH v6 2/2] dt-bindings: hwmon: (adt7475) Added missing adt7475 documentation

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Date:   Wed, 5 Feb 2020 00:48:01 +0000
From:   Logan Shaw <Logan.Shaw@...iedtelesis.co.nz>
To:     "robh@...nel.org" <robh@...nel.org>
CC:     "linux@...ck-us.net" <linux@...ck-us.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Joshua Scott <Joshua.Scott@...iedtelesis.co.nz>,
        Chris Packham <Chris.Packham@...iedtelesis.co.nz>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v6 2/2] dt-bindings: hwmon: (adt7475) Added missing
 adt7475 documentation

Just a gentle reminder as this thread has been quiet for a while. Rob,
I would appreciate some feedback on my question from my previous email. 

To add a little more detail: I want to avoid simply checking for the
existence of a property in the DTS as that could break compatibility
with codebases implementing their own method of handling the attenuator
bypass.

On Thu, 2020-01-30 at 03:07 +0000, Logan Shaw wrote:
> On Mon, 2020-01-27 at 09:48 -0600, Rob Herring wrote:
> > On Mon, Jan 27, 2020 at 11:10:14AM +1300, Logan Shaw wrote:
> > > Added a new file documenting the adt7475 devicetree and added the
> > > four
> > > new properties to it.
> > > 
> > > Signed-off-by: Logan Shaw <logan.shaw@...iedtelesis.co.nz>
> > > ---
> > > ---
> > >  .../devicetree/bindings/hwmon/adt7475.yaml    | 95
> > > +++++++++++++++++++
> > >  1 file changed, 95 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > > b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > > new file mode 100644
> > > index 000000000000..450da5e66e07
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > > @@ -0,0 +1,95 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > 
> > Dual license new bindings please:
> > 
> > (GPL-2.0-only OR BSD-2-Clause)
> > 
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/adt7475.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: ADT7475 hwmon sensor
> > > +
> > > +maintainers:
> > > +  - Jean Delvare <jdelvare@...e.com>
> > > +
> > > +description: |
> > > +  The ADT7473, ADT7475, ADT7476, and ADT7490 are thermal
> > > monitors
> > > and multiple
> > > +  PWN fan controllers.
> > > +
> > > +  They support monitoring and controlling up to four fans (the
> > > ADT7490 can only
> > > +  control up to three). They support reading a single on chip
> > > temperature
> > > +  sensor and two off chip temperature sensors (the ADT7490
> > > additionally
> > > +  supports measuring up to three current external temperature
> > > sensors with
> > > +  series resistance cancellation (SRC)).
> > > +
> > > +  Datasheets:
> > > +  https://www.onsemi.com/pub/Collateral/ADT7473-D.PDF
> > > +  https://www.onsemi.com/pub/Collateral/ADT7475-D.PDF
> > > +  https://www.onsemi.com/pub/Collateral/ADT7476-D.PDF
> > > +  https://www.onsemi.com/pub/Collateral/ADT7490-D.PDF
> > > +
> > > +  Description taken from omsemiconductors specification sheets,
> > > with minor
> > 
> > omsemi?
> >  ^
> > 
> > > +  rephrasing.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - adi,adt7473
> > > +      - adi,adt7475
> > > +      - adi,adt7476
> > > +      - adi,adt7490
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  bypass-attenuator-in0:
> > 
> > Needs a vendor prefix and a type ref. 
> > 
> > > +    description: |
> > > +      Configures bypassing the individual voltage input
> > > +      attenuator, on in0. This is supported on the ADT7476 and
> > > ADT7490.
> > > +      If set to a non-zero integer the attenuator is bypassed,
> > > if
> > > set to
> > > +      zero the attenuator is not bypassed. If the property is
> > > absent then
> > > +      the config register is not modified.
> > 
> > Sounds like this could be boolean? If not, define a schema for what
> > are 
> > valid values.
> 
> By boolean are you referring to a dts property that is evaluated
> (using
> function of_property_read_bool) as true/false, depending on its
> presence? For example "regulator-always-on" in:
> /Documentation/devicetree/bindings/regulator/regulator.yaml .
> 
> > 
> > > +    maxItems: 1
> > > +
> > > +  bypass-attenuator-in1:
> > > +    description: |
> > > +      Configures bypassing the individual voltage input
> > > +      attenuator, on in1. This is supported on the ADT7473,
> > > ADT7475,
> > > +      ADT7476 and ADT7490. If set to a non-zero integer the
> > > attenuator
> > > +      is bypassed, if set to zero the attenuator is not
> > > bypassed.
> > > If the
> > > +      property is absent then the config register is not
> > > modified.
> > > +    maxItems: 1
> > > +
> > > +  bypass-attenuator-in3:
> > > +    description: |
> > > +      Configures bypassing the individual voltage input
> > > +      attenuator, on in3. This is supported on the ADT7476 and
> > > ADT7490.
> > > +      If set to a non-zero integer the attenuator is bypassed,
> > > if
> > > set to
> > > +      zero the attenuator is not bypassed. If the property is
> > > absent then
> > > +      the config register is not modified.
> > > +    maxItems: 1
> > > +
> > > +  bypass-attenuator-in4:
> > 
> > These 4 could be a single entry under patternProperties.
> > 
> > 
> > > +    description: |
> > > +      Configures bypassing the individual voltage input
> > > +      attenuator, on in4. This is supported on the ADT7476 and
> > > ADT7490.
> > > +      If set to a non-zero integer the attenuator is bypassed,
> > > if
> > > set to
> > > +      zero the attenuator is not bypassed. If the property is
> > > absent then
> > > +      the config register is not modified.
> > > +    maxItems: 1
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +
> > > +examples:
> > > +  - |
> > > +    i2c {
> > > +      #address-cells = <1>;
> > > +      #size-cells = <0>;
> > > +
> > > +      hwmon@2e {
> > > +        compatible = "adi,adt7476";
> > > +        reg = <0x2e>;
> > > +        bypass-attenuator-in0 = <1>;
> > > +        bypass-attenuator-in1 = <0>;
> > > +      };
> > > +    };
> > > +...
> > > -- 
> > > 2.25.0
> > >