linux-kernel - Re: [PATCH 2/4] nvmem: add generic driver for devices with MMIO access

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Date:   Thu, 2 Feb 2023 10:24:44 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH 2/4] nvmem: add generic driver for devices with MMIO
 access

Il 01/02/23 07:47, Rafał Miłecki ha scritto:
> From: Rafał Miłecki <rafal@...ecki.pl>
> 
> With nvmem layouts in place we should now work on plain content access
> NVMEM drivers (e.g. MMIO one). Actual NVMEM content handling should go
> to layout drivers.
> 
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>

I agree but if you want to really bring on this change, you should add
some kind of write support... and clocks... and regulators with different
voltage levels (write/fuse-blow voltage, read voltage if any)...

Describing this entire thing in device-tree should be possible, but then
some SoCs may need a specific register sequence in order to enter writing
mode, which is something that you can't just put in devicetree, so this
driver should be a framework on its own - hence not as simple as proposed.

Regards,
Angelo