[PATCH v11 2/3] dt-bindings: rtc: Add property for Raspberry Pi 5 RTC

[Alexandre Belloni]

On 14/10/2026 10:30:15+0200, Sander Speetjens wrote:
> The Raspberry Pi 5 has a built-in RTC that can be battery-backed
> via the VBAT pin. When a rechargeable coin cell is used, the
> hardware requires a trickle-charge voltage to keep the battery
> topped up.
> 
> Expose the trickle-voltage-millivolt DT property so the driver can
> program the correct charge voltage for board specific configurations with
> the attached battery.
> 

You are missing a comment from Krzysztof:
"Commit msg could explain that you do not reference rtc.yaml due to node
naming rule."

> Acked-by: Conor Dooley <conor.dooley at microchip.com>
> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>
> Signed-off-by: Sander Speetjens <sander.speetjens at gmail.com>
> ---
> V10 -> V11: No changes
> 
> V9 -> V10: No changes
> 
> V8 -> V9: No changes
> 
> V7 -> V8: No changes
> 
> V6 -> V7: No changes
> 
> V5 -> V6: No changes
> 
> V4 -> V5: As discussed with Conor Dooley, the reff to uint32 is removed
> and a PR is made on dt-schema adding millivolt to property-units.yaml
> 
> V3 -> V4: Add a reff to uint32
> 
> V2 -> V3: Fixed the firmware property naming
> 
> V1 -> V2: As discussed with Krzysztof Kozlowski, this property is folded into
> the existing raspberrypi,bcm2835-firmware properties.
> 
>  .../bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml      | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> index 983ea80eaec9..dc71fd57834e 100644
> --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> @@ -133,6 +133,11 @@ properties:
>      required:
>        - compatible
>  
> +  trickle-voltage-millivolt:
> +    $ref: /schemas/rtc/rtc.yaml#/properties/trickle-voltage-millivolt
> +    minimum: 1300
> +    maximum: 5000
> +
>  required:
>    - compatible
>    - mboxes
> @@ -144,6 +149,7 @@ examples:
>      firmware {
>          compatible = "raspberrypi,bcm2835-firmware", "simple-mfd";
>          mboxes = <&mailbox>;
> +        trickle-voltage-millivolt = <3300>;
>  
>          firmware_clocks: clocks {
>              compatible = "raspberrypi,firmware-clocks";
> -- 
> 2.56.0
> 

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