Re: [RFC v2 5/5] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver

From: Cristian Marussi <cristian.marussi@arm.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Rob Herring <robh@kernel.org>,
	AKASHI Takahiro <takahiro.akashi@linaro.org>,
	sudeep.holla@arm.com, krzysztof.kozlowski+dt@linaro.org,
	conor+dt@kernel.org, Oleksii_Moisieiev@epam.com,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org
Subject: Re: [RFC v2 5/5] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver
Date: Mon, 9 Oct 2023 16:08:13 +0100	[thread overview]
Message-ID: <ZSQXXW1NRiCpsENu@e120937-lin> (raw)
In-Reply-To: <CACRpkdY=eza0TuBRDb_cWk9LM2qNQg76rZSgWa-RP4TYLL=Ppw@mail.gmail.com>

On Mon, Oct 09, 2023 at 03:13:24PM +0200, Linus Walleij wrote:
> On Mon, Oct 9, 2023 at 11:08 AM Cristian Marussi
> <cristian.marussi@arm.com> wrote:
> 
> > > > +    gpio0: gpio@0 {
> > > > +        compatible = "pin-control-gpio";
> > > > +        gpio-controller;
> > > > +        #gpio-cells = <2>;
> > > > +        gpio-ranges = <&scmi_pinctrl 0 10 5>,
> > > > +                      <&scmi_pinctrl 5 0 0>;
> > > > +        gpio-ranges-group-names = "",
> > > > +                                  "pinmux_gpio";
> > > > +    };
> > >
> >
> > Assuming the above &scmi_pinctrl refers to the protocol node as we
> > usually do,
> 
> No it does not, it is a three-layer cake.
> 
> scmi <-> scmi_pinctrl <-> scmi_gpio
> 
> it refers to the scmi_pinctrl node.
> 

Thanks, this explains a lot.
Cristian

> There is no SCMI GPIO protocol, instead SCMI is using the
> operations already available in the pin controller to exercise
> GPIO. Generic pin control has operations to drive lines for
> example, and Takahiro is adding the ability for a generic pin
> controller to also read a line.

> 
> Yours,
> Linus Walleij