Re: [RFC PATCH v1 3/4] rust: add RTC core abstractions and data structures

["Danilo Krummrich" <dakr@kernel.org>]

On Sun Jan 4, 2026 at 7:06 AM CET, Ke Sun wrote:
> Add Rust abstractions for RTC (Real-Time Clock) devices, including:
>
> - Data structures: RtcTime, RtcWkAlrm, RtcParam wrappers for RTC types
> - RtcDevice: Safe wrapper for struct rtc_device
> - DriverGeneric trait: Generic RTC driver trait over bus types
> - RtcOperations trait: VTable for RTC device operations
> - Bus abstractions: PlatformBus, AmbaBus, I2cBus implementations

This is my main concern with this patch: It bakes bus (device) code (e.g.
platform AMBA and I2C) into the RTC code, effectively duplicating infrastructure
where it does not belong to in the first place and limites on which bus RTC
devices can be registered artificially.

The driver model has a loosely coupled design between bus and class device code,
such that class devices can be registered freely from any driver driving a bus
device. There can also be more complicated topologies considering the auxiliary
bus, mfd, etc.

Please remove the duplicated bus (device) code and helper types and macros, such
as BusRegistration, impl_bus!, etc. Instead, please have a look at how the PWM
code works and incorporate the design.

Additionally, you can utilize the AsBusDevice trait to find the concrete bus
device (e.g. AMBA) in your class device callbacks from the generic parent device
of your RTC device.

I will take a more thorough look at the code from the driver core side of things
once this has been addressed.

Thanks,
Danilo