Re: [PATCH 1/3] dt-bindings: rtc: Add Raspberry Pi 5 RTC binding

[Krzysztof Kozlowski <krzk@kernel.org>]

On 09/09/2026 22:24, Sander Speetjens wrote:
> Thanks for your response
> 
>> And more important, where is any interface to actually control the RTC?
>> I see nothing, so your firmware is? Then this is not a separate device
>> and you just added DTS for your driver, which is a no go (see writing
>> bindings).
> 
> The RTC is a physical, battery-backed RTC, but the Raspberry Pi firmware
> exposes its register interface exclusively through the firmware mailbox.
> I initially used a firmware phandle so the RTC driver could obtain the
> existing rpi_firmware instance.
> 
> Based on your comment, I think it is more appropriate to model
> the RTC as a child device of rpi-firmware,
> referencing to the existing firmware clock/reset/power services,
> and have the driver obtain the firmware interface from its parent
> rather than adding a phandle solely for driver plumbing.
> Which also means moving this to arm/bcm/raspberrypi,bcm2835-firmware.yaml
> 

Whether device has separate node, depends on it having dedicated
resources. I don't see such here, so unlikely it should have a node in
the first place (see writing bindings or DTS101 where exactly this
question is asked).

Best regards,
Krzysztof