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Date: Thu, 25 Jan 2024 12:01:06 +0100
Message-Id: <CYNQHXOZ73YR.3QODFI2X08KC6@bootlin.com>
From: =?utf-8?q?Th=C3=A9o_Lebrun?= <theo.lebrun@bootlin.com>
Subject: Re: [PATCH v3 04/17] dt-bindings: soc: mobileye: add EyeQ5 OLB
 system controller
Cc: "Gregory CLEMENT" <gregory.clement@bootlin.com>, "Michael Turquette"
 <mturquette@baylibre.com>, "Stephen Boyd" <sboyd@kernel.org>, "Krzysztof
 Kozlowski" <krzysztof.kozlowski+dt@linaro.org>, "Conor Dooley"
 <conor+dt@kernel.org>, "Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
 "Linus Walleij" <linus.walleij@linaro.org>,
 =?utf-8?q?Rafa=C5=82_Mi=C5=82ecki?= <rafal@milecki.pl>, "Philipp Zabel"
 <p.zabel@pengutronix.de>, "Vladimir Kondratiev"
 <vladimir.kondratiev@mobileye.com>, <linux-mips@vger.kernel.org>,
 <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>, "Thomas Petazzoni"
 <thomas.petazzoni@bootlin.com>, "Tawfik Bayouk"
 <tawfik.bayouk@mobileye.com>, <linux-gpio@vger.kernel.org>
To: "Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>, "Rob Herring"
 <robh@kernel.org>
References: <20240123-mbly-clk-v3-0-392b010b8281@bootlin.com>
 <20240123-mbly-clk-v3-4-392b010b8281@bootlin.com>
 <20240124151405.GA930997-robh@kernel.org>
 <dd7e723d-3c4c-4edf-afc2-51db9a074efa@linaro.org>
In-Reply-To: <dd7e723d-3c4c-4edf-afc2-51db9a074efa@linaro.org>

Hello,

On Thu Jan 25, 2024 at 8:51 AM CET, Krzysztof Kozlowski wrote:
> On 24/01/2024 16:14, Rob Herring wrote:
> >> +
> >> +      pinctrl-b {
> >> +        compatible =3D "mobileye,eyeq5-b-pinctrl";
> >> +        #pinctrl-cells =3D <1>;
> >> +      };
> >> +    };
> >=20
> > This can all be simplified to:
> >=20
> > system-controller@e00000 {
> >     compatible =3D "mobileye,eyeq5-olb", "syscon";
> >     reg =3D <0xe00000 0x400>;
> >     #reset-cells =3D <2>;
> >     #clock-cells =3D <1>;
> >     clocks =3D <&xtal>;
> >     clock-names =3D "ref";
> >=20
> >     pins { ... };
> > };
> >=20
> > There is no need for sub nodes unless you have reusable blocks or each=
=20
> > block has its own resources in DT.
>
> Yes, however I believe there should be resources here: each subnode
> should get its address space. This is a bit tied to implementation,
> which currently assumes "everyone can fiddle with everything" in this blo=
ck.
>
> Theo, can you draw memory map?

It would be a mess. I've counted things up. The first 147 registers are
used in this 0x400 block. There are 31 individual blocks, with 7
registers unused (holes to align next block).

Functions are reset, clocks, LBIST, MBIST, DDR control, GPIO,
accelerator control, CPU entrypoint, PDTrace, IRQs, chip info & ID
stuff, control registers for PCIe / eMMC / Eth / SGMII / DMA / etc.

Some will never get used from Linux, others might. Maybe a moderate
approach would be to create ressources for major blocks and make it
evolve organically, without imposing that all uses lead to a new
ressource creation.

Thanks,

--
Th=C3=A9o Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com