linux-kernel - Re: [PATCH v2 1/2] dt-bindings: arm: stm32: add simple-mfd compatible for tamp node

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Date:   Mon, 26 Oct 2020 09:36:56 -0500
From:   Rob Herring <robh@...nel.org>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Christophe Roullier <christophe.roullier@...com>,
        kernel@...gutronix.de, Arnaud Pouliquen <arnaud.pouliquen@...com>,
        devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: arm: stm32: add simple-mfd
 compatible for tamp node

On Wed, Oct 21, 2020 at 12:28:55PM +0200, Ahmad Fatoum wrote:
> The stm32mp1 TAMP (Tamper and backup registers) does tamper detection
> and features 32 backup registers that, being in the RTC domain, may
> survive even with Vdd switched off.
> 
> This makes it suitable for use to communicate a reboot mode from OS
> to bootloader via the syscon-reboot-mode binding. Add a "simple-mfd"
> to support probing such a child node. The actual reboot mode
> node could then be defined in a board.dts or fixed up by the bootloader.

'simple-mfd' implies there is no dependency on the parent node for the 
child (such as the regmap perhaps). Is that the case here?

> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
> ---
> v1 available here:
> https://lore.kernel.org/linux-arm-kernel/20200916142216.25142-1-a.fatoum@pengutronix.de/
> 
> v1 -> v2:
>  - new patch, rebased on top of
>    https://lore.kernel.org/r/20201014125441.2457-1-arnaud.pouliquen@st.com
> ---
>  .../devicetree/bindings/arm/stm32/st,stm32-syscon.yaml       | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml b/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
> index 6634b3e0853e..4684017a42e4 100644
> --- a/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
> +++ b/Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml
> @@ -19,8 +19,11 @@ properties:
>                - st,stm32mp151-pwr-mcu
>                - st,stm32-syscfg
>                - st,stm32-power-config
> -              - st,stm32-tamp
>            - const: syscon
> +      - items:
> +          - const: st,stm32-tamp
> +          - const: syscon
> +          - const: simple-mfd
>  
>    reg:
>      maxItems: 1
> -- 
> 2.28.0
>