Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230605-ep93xx-v3-0-3d63a5f1103e@maquefel.me>
 <20230605-ep93xx-v3-35-3d63a5f1103e@maquefel.me> <4b0f8b39-bec5-6f5d-1b98-8145e334ed94@linaro.org>
 <2c7e838ae4e49b72185626935f886d07895e8192.camel@maquefel.me>
In-Reply-To: <2c7e838ae4e49b72185626935f886d07895e8192.camel@maquefel.me>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Sat, 29 Jul 2023 22:59:20 +0200
Message-ID: <CACRpkdYA2MLdX5xY-rTcKyKH2eFXZyHHXcX9G-vdWT5GmChwaA@mail.gmail.com>
Subject: Re: [PATCH v3 35/42] ARM: dts: ep93xx: add ts7250 board
To:     Nikita Shubin <nikita.shubin@maquefel.me>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Hartley Sweeten <hsweeten@visionengravers.com>,
        Lennert Buytenhek <kernel@wantstofly.org>,
        Alexander Sverdlin <alexander.sverdlin@gmail.com>,
        Michael Peters <mpeters@embeddedts.com>,
        Kris Bahnsen <kris@embeddedts.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, Jul 24, 2023 at 3:45=E2=80=AFPM Nikita Shubin <nikita.shubin@maquef=
el.me> wrote:

> > > +       nand-controller@60000000 {
> >
> > Where is this address? It does not work like that. If this is part of
> > SoC, then should be in DTSI and part of soc node. If not, then it is
> > some other bus which needs some description. Top-level is not a bus.
> >
>
> It's some kind of EBI, but it doesn't need a driver it is transparent
> on ts7250, the logic is controlled through installed CPLD.
>
> The EBI it self is a part of the SoC through:
>
> https://elixir.bootlin.com/linux/v6.5-rc3/source/arch/arm/mach-ep93xx/soc=
.h#L35
>
> EP93XX_CS0_PHYS_BASE_ASYNC to EP93XX_CS0_PHYS_BASE_SYNC.
>
> So for ts7250 this includes:
>
> - NAND
> - m48t86
> - watchdog
>
> I don't even know how to represent it correctly, would "simple-bus"
> with "ranges" defined suit here, so it will represent hierarchy but
> won't do anything ?

Check how I solved this on the IXP4xx EBI for an example:
Documentation/devicetree/bindings/memory-controllers/intel,ixp4xx-expansion=
-bus-controller.yaml

Top level bus inside soc:
arch/arm/boot/dts/intel/ixp/intel-ixp4xx.dtsi
Example platform:
arch/arm/boot/dts/intel/ixp/intel-ixp42x-linksys-nslu2.dts

Notice chip select number in first cell.

I think you want to do something similar here?

Yours,
Linus Walleij