Re: [PATCH v12 2/5] rust: io: separate generic I/O helpers from MMIO implementation

[Alice Ryhl <aliceryhl@google.com>]

On Wed, Jan 21, 2026 at 10:22:08PM +0200, Zhi Wang wrote:
> The previous Io<SIZE> type combined both the generic I/O access helpers
> and MMIO implementation details in a single struct. This coupling prevented
> reusing the I/O helpers for other backends, such as PCI configuration
> space.
> 
> Establish a clean separation between the I/O interface and concrete
> backends by separating generic I/O helpers from MMIO implementation.
> 
> Introduce a new trait hierarchy to handle different access capabilities:
> 
> - IoCapable<T>: A marker trait indicating that a backend supports I/O
>   operations of a certain type (u8, u16, u32, or u64).
> 
> - Io trait: Defines fallible (try_read8, try_write8, etc.) and infallibile
>   (read8, write8, etc.) I/O methods with runtime bounds checking and
>   compile-time bounds checking.
> 
> - IoKnownSize trait: The marker trait for types support infallible I/O
>   methods.
> 
> Move the MMIO-specific logic into a dedicated Mmio<SIZE> type that
> implements the Io traits. Rename IoRaw to MmioRaw and update consumers to
> use the new types.
> 
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Cc: Alice Ryhl <aliceryhl@google.com>
> Cc: Bjorn Helgaas <helgaas@kernel.org>
> Cc: Gary Guo <gary@garyguo.net>
> Cc: Danilo Krummrich <dakr@kernel.org>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Zhi Wang <zhiw@nvidia.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>