linux-kernel - Re: [PATCH v7 10/12] nvmem: s32g2_siul2: add NVMEM driver for SoC information

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Message-ID: <0973e6d1-2823-4bfb-be73-b532c6f86784@oss.nxp.com>
Date: Mon, 4 Aug 2025 10:12:08 +0300
From: Andrei Stefanescu <andrei.stefanescu@....nxp.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
 <brgl@...ev.pl>, Rob Herring <robh@...nel.org>, krzk+dt@...nel.org,
 Conor Dooley <conor+dt@...nel.org>, Chester Lin <chester62515@...il.com>,
 Matthias Brugger <mbrugger@...e.com>,
 Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>,
 Larisa Grigore <larisa.grigore@....com>, Lee Jones <lee@...nel.org>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, aisheng.dong@....com,
 Jacky Bai <ping.bai@....com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, "Rafael J . Wysocki" <rafael@...nel.org>,
 Srinivas Kandagatla <srini@...nel.org>
Cc: "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, NXP S32 Linux Team <s32@....com>,
 Christophe Lizzi <clizzi@...hat.com>, Alberto Ruiz <aruizrui@...hat.com>,
 Enric Balletbo <eballetb@...hat.com>, echanude@...hat.com,
 Pengutronix Kernel Team <kernel@...gutronix.de>, imx@...ts.linux.dev,
 Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH v7 10/12] nvmem: s32g2_siul2: add NVMEM driver for SoC
 information

Hi Krzysztof,

Thank you for the quick response!
On 02/08/2025 11:32, Krzysztof Kozlowski wrote:
> On 02/08/2025 10:28, Krzysztof Kozlowski wrote:
>> On 01/08/2025 16:36, Andrei Stefanescu wrote:
>>> Apart from the proposed NVMEM driver, there is also an option of exporting
>>> a syscon regmap for the registers which provide information about the SoC.
>>>
>>> I have seen that typically NVMEM drivers export information read from fuses
>>> but I think having a NVMEM driver is nicer way to access the information
>>> instead of using a syscon regmap and manually extracting the needed bits. 
>>
>>
>> nvmem is not a syscon. Mixing these two means device is something
>> completely else.

Yes, I don't want to mix them. The driver will either be a NVMEM driver or
a syscon. These registers are read-only. I suggested NVMEM because it's a
an abstraction layer which makes it easier for drivers which want to use
that information without knowing where to actually read it i.e. reg address,
bit mask.

What do think? Which one would be better? Do you have other suggestions?

Best regards,
Andrei

> 
> 
> ... and yes, I am aware that three FSL/NXP bindings use nvmem as syscon
> already. People are mixing hardware description (nvmem) with some
> purpose for drivers (syscon) forgetting that syscon are miscellaneous
> SoC internal registers, not non-volatile memory.
> 
> Best regards,
> Krzysztof