Re: [PATCH 1/2] dt-bindings: at24: add ST M24C32-D Additional Write lockable page

Bartosz Golaszewski
2023-10-12T12:57:35Z

On Thu, Oct 12, 2023 at 1:57 PM Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Oct 10, 2023 at 09:09:25PM +0200, Marek Vasut wrote:
> > The ST M24C32-D behaves as a regular M24C32, except for the -D variant
> > which uses up another I2C address for Additional Write lockable page.
> > This page is 32 Bytes long and can contain additional data. Document
> > compatible string for it, so users can describe that page in DT. Note
> > that users still have to describe the main M24C32 area separately as
> > that is on separate I2C address from this page.
>
> So 2 nodes for 1 device? Wouldn't it make more sense for the 1 node to
> have 2 addresses?
>

This is in line with what we have been doing so far for 24cs and 24mac
variants. Here[1] is the series that first added support for those
special areas.

The way nvmem works, we'd need to register two nvmem devices anyway as
children of the i2c device associated with the at24 chip. Not worth
the additional complexity this would entail if you ask me.

Bartosz

[1] https://lore.kernel.org/lkml/1465202936-16832-1-git-send-email-bgolaszewski@baylibre.com/

> >
> > Signed-off-by: Marek Vasut <marex@denx.de>
> > ---
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> > Cc: Conor Dooley <conor+dt@kernel.org>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: devicetree@vger.kernel.org
> > Cc: linux-i2c@vger.kernel.org
> > ---
> > Documentation/devicetree/bindings/eeprom/at24.yaml | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/eeprom/at24.yaml b/Documentation/devicetree/bindings/eeprom/at24.yaml
> > index 98139489d4b5c..7be127e9b2507 100644
> > --- a/Documentation/devicetree/bindings/eeprom/at24.yaml
> > +++ b/Documentation/devicetree/bindings/eeprom/at24.yaml
> > @@ -67,6 +67,8 @@ properties:
> > pattern: cs16$
> > - items:
> > pattern: c32$
> > + - items:
> > + pattern: c32d-wl$
> > - items:
> > pattern: cs32$
> > - items:
> > --
> > 2.40.1
> >