linux-kernel - Re: [PATCH RFC v1 2/2] devicetree: bindings: bus: add Wiegand driver documentation

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Message-ID: <CACRpkdZKAzsdhyky1bEax3Jra0+MLYbu+LNWuk2KGAfEkBvBLQ@mail.gmail.com>
Date:   Mon, 22 Aug 2022 09:21:44 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Martin Zaťovič <m.zatovic1@...il.com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        mani@...nel.org, hemantk@...eaurora.org, elder@...aro.org,
        f.fainelli@...il.com, Michael.Srba@...nam.cz,
        jeffrey.l.hugo@...il.com, gregkh@...uxfoundation.org,
        bjorn.andersson@...aro.org, saravanak@...gle.com,
        krzysztof.kozlowski+dt@...aro.org, robh+dt@...nel.org
Subject: Re: [PATCH RFC v1 2/2] devicetree: bindings: bus: add Wiegand driver documentation

On Thu, Jul 28, 2022 at 11:17 AM Martin Zaťovič <m.zatovic1@...il.com> wrote:

> Wiegand write-only driver requires definitions of two GPIO lines
> in the devicetree. This adds the documentation of their
> definitions.

On top of the other comments:

> +  Both data lines are initially pulled up.

That makes it sound like they are both open drain, right? Just like I2C.

> +  wiegand-data-hi-gpios:
> +  wiegand-data-lo-gpios:

So these should be tagged with (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)
See the I2C bindings in
Documentation/devicetree/bindings/i2c/i2c-gpio.yaml

> +        wiegand-data-hi-gpios = <&gpio2 1 GPIO_ACTIVE_HIGH>;
> +        wiegand-data-lo-gpios = <&gpio2 2 GPIO_ACTIVE_HIGH>;

 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) on both then!

Yours,
Linus Walleij