linux-kernel - Re: [PATCH v1 3/3] dt-bindings: iio: afe: Add hwmon example

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Message-ID: <89820e72-dcdc-67a8-b83d-5657d66d910a@axentia.se>
Date:   Tue, 11 Jun 2019 11:14:10 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     Mylène Josserand <mylene.josserand@...tlin.com>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "knaack.h@....de" <knaack.h@....de>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>
CC:     "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "thomas.petazzoni@...tlin.com" <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v1 3/3] dt-bindings: iio: afe: Add hwmon example

On 2019-06-11 11:56, Mylène Josserand wrote:
> With the support of CHAN_INFO_PROCESSED in voltage-divider,
> it is possible to read the processed values directly from iio's
> sysfs entries or by using iio-hwmon. Add an example for this last
> use case.

As I wrote in response to the cover letter, I think iio-hwmon
could "consume" voltage dividers just fine before adding the
processed channel, and while more examples might be good,
there is really no specific relation between iio-hwmon and
voltage dividers. Adding iio-hwmon examples to each and every
iio binding seems pointless. So, I see little reason to add
such examples here.

But if everyone else wants it, don't let me stand in the way...

Cheers,
Peter

> Signed-off-by: Mylène Josserand <mylene.josserand@...tlin.com>
> ---
>  .../bindings/iio/afe/voltage-divider.txt           | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
> index b452a8406107..f7e1c7cb2744 100644
> --- a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
> +++ b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
> @@ -51,3 +51,27 @@ sysv {
>  		spi-max-frequency = <1000000>;
>  	};
>  };
> +
> +It is also possible to retrieve the processed values using hwmon node:
> +
> +div0: div0 {
> +	compatible = "voltage-divider";
> +	io-channels = <&adc0 0>; /* Channel 0 of the ADC */
> +	output-ohms = <47>; /* R2 */
> +	full-ohms = <73>; /* R1 (26) + R2 (47) */
> +	#io-channel-cells = <1>;
> +};
> +
> +div1: div1 {
> +	compatible = "voltage-divider";
> +	io-channels = <&adc0 1>; /* Channel 1 of the ADC */
> +	output-ohms = <47>; /* R2 */
> +	full-ohms = <115>; /* R1 (68) + R2 (47) */
> +	#io-channel-cells = <1>;
> +};
> +
> +iio-hwmon {
> +	compatible = "iio-hwmon";
> +	io-channels = <&div0 0>, <&div1 0>;
> +	io-channel-names = "3v3", "usb";
> +};
>