linux-kernel - Re: [PATCH 2/6] dt-bindings: rtc: stm32: add alarm A out property to select output

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Date:   Wed, 4 May 2022 22:27:47 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Valentin Caron <valentin.caron@...s.st.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Gabriel Fernandez <gabriel.fernandez@...s.st.com>,
        Amelie Delaunay <amelie.delaunay@...s.st.com>,
        linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] dt-bindings: rtc: stm32: add alarm A out property to
 select output

Hello,

On 04/05/2022 15:06:13+0200, Valentin Caron wrote:
> STM32 RTC can pulse some SOC pins when an alarm of RTC expires.
> 
> This patch adds property to activate alarm A output. The pulse can
> output on three pins RTC_OUT1, RTC_OUT2, RTC_OUT2_RMP
> (PC13, PB2, PI8 on stm32mp15) (PC13, PB2, PI1 on stm32mp13).
> 
> Signed-off-by: Valentin Caron <valentin.caron@...s.st.com>
> ---
>  .../devicetree/bindings/rtc/st,stm32-rtc.yaml | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/rtc/st,stm32-rtc.yaml b/Documentation/devicetree/bindings/rtc/st,stm32-rtc.yaml
> index 56d46ea35c5d..71e02604e8de 100644
> --- a/Documentation/devicetree/bindings/rtc/st,stm32-rtc.yaml
> +++ b/Documentation/devicetree/bindings/rtc/st,stm32-rtc.yaml
> @@ -59,6 +59,13 @@ properties:
>        Refer to <include/dt-bindings/rtc/rtc-stm32.h> for the supported values.
>        Pinctrl state named "default" may be defined to reserve pin for RTC output.
>  
> +  st,alarm:
> +    $ref: "/schemas/types.yaml#/definitions/uint32"
> +    description: |
> +      To select and enable RTC Alarm A output.
> +      Refer to <include/dt-bindings/rtc/rtc-stm32.h> for the supported values.
> +      Pinctrl state named "default" may be defined to reserve pin for RTC output.
> +
>  allOf:
>    - if:
>        properties:
> @@ -75,6 +82,9 @@ allOf:
>          st,lsco:
>            maxItems: 0
>  
> +        st,alarm:
> +          maxItems: 0
> +
>          clock-names: false
>  
>        required:
> @@ -95,6 +105,9 @@ allOf:
>          st,lsco:
>            maxItems: 0
>  
> +        st,alarm:
> +          maxItems: 0
> +
>        required:
>          - clock-names
>          - st,syscfg
> @@ -117,6 +130,9 @@ allOf:
>          st,lsco:
>            maxItems: 1
>  
> +        st,alarm:
> +          maxItems: 1
> +
>        required:
>          - clock-names
>  
> @@ -153,8 +169,9 @@ examples:
>        clocks = <&rcc RTCAPB>, <&rcc RTC>;
>        clock-names = "pclk", "rtc_ck";
>        interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;
> +      st,alarm = <RTC_OUT1>;
>        st,lsco = <RTC_OUT2_RMP>;

Shouldn't that be exactly the opposite? You have two pins that can
output different functions. The property should be the pin and the value
the function. I'd go even further and I would say this is actually
pinmuxing.


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com