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Date:   Sat, 3 Sep 2022 04:39:42 +0200
From:   Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Pali =?UTF-8?B?Um9ow6Fy?= <pali@kernel.org>,
        Gregory Clement <gregory.clement@bootlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ARM: dts: turris-omnia: Add mcu node
Message-ID: <20220903043828.6afd3ab4@thinkpad>
In-Reply-To: <YxE2JqJutZ0ilghH@lunn.ch>
References: <20220819131152.6513-1-pali@kernel.org>
        <20220831142809.lcmnv3l4rnulo522@pali>
        <YxE2JqJutZ0ilghH@lunn.ch>
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On Fri, 2 Sep 2022 00:45:58 +0200
Andrew Lunn <andrew@lunn.ch> wrote:

> On Wed, Aug 31, 2022 at 04:28:09PM +0200, Pali Roh=C3=A1r wrote:
> > PING?
> >=20
> > On Friday 19 August 2022 15:11:52 Pali Roh=C3=A1r wrote: =20
> > > At i2c address 0x2a is MCU command interface which provides access to=
 GPIOs
> > > connected to Turris Omnia MCU. So define mcu node in Turris Omnia DTS=
 file.
> > >=20
> > > Signed-off-by: Pali Roh=C3=A1r <pali@kernel.org>
> > >=20
> > > ---
> > > Same change was already sent to U-Boot project together with driver. =
As
> > > Turris Omnia DTS file is shared between Linux kernel U-Boot, I'm send=
ing
> > > this change also in Linux. There is a plan to write also Linux driver=
 for
> > > Turris Omnia MCU, like there is already in U-Boot.
> > >=20
> > > https://source.denx.de/u-boot/u-boot/-/commit/832738974806e6264a3d0ac=
2aaa92d0f662fd128
> > > https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/gpio/turri=
s_omnia_mcu.c
> > > ---
> > >  arch/arm/boot/dts/armada-385-turris-omnia.dts | 8 +++++++-
> > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > >=20
> > > diff --git a/arch/arm/boot/dts/armada-385-turris-omnia.dts b/arch/arm=
/boot/dts/armada-385-turris-omnia.dts
> > > index f4878df39753..f655e9229d68 100644
> > > --- a/arch/arm/boot/dts/armada-385-turris-omnia.dts
> > > +++ b/arch/arm/boot/dts/armada-385-turris-omnia.dts
> > > @@ -184,7 +184,13 @@
> > >  			#size-cells =3D <0>;
> > >  			reg =3D <0>;
> > > =20
> > > -			/* STM32F0 command interface at address 0x2a */
> > > +			/* MCU command i2c API */
> > > +			mcu: mcu@2a {
> > > +				compatible =3D "cznic,turris-omnia-mcu";
> > > +				reg =3D <0x2a>;
> > > +				gpio-controller;
> > > +				#gpio-cells =3D <3>;
> > > +			}; =20
>=20
> Please document the binding, preferably in yaml.
>=20
> I'm also not sure what the DT people will say about the node name mcu.
> I don't see any examples of that in the binding documentation. They
> might request you rename it to gpio-controller, unless it does more
> than GPIO? And if it does do more than GPIO we are then into mfd
> territory, and the binding then becomes much more interesting. Then we
> start the questions, are you defining a ABI now, before there is even
> a driver for it?

Most probably mfd territory. It is at least a gpio-controller,
reset-controller and watchdog.

Marek