Re: [PATCH v2 4/5] rust: io: add `register!` macro

["Alexandre Courbot" <acourbot@nvidia.com>]

On Wed Jan 21, 2026 at 4:23 PM JST, Alexandre Courbot wrote:
> Add a macro for defining hardware register types with I/O accessors.
>
> Each register field is represented as a `Bounded` of the appropriate bit
> width, ensuring field values are never silently truncated.
>
> Fields can optionally be converted to/from custom types, either fallibly
> or infallibly.
>
> The address of registers can be direct, relative, or indexed, supporting
> most of the patterns in which registers are arranged.
>
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  rust/kernel/io.rs          |    1 +
>  rust/kernel/io/register.rs | 1198 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 1199 insertions(+)
>
> diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
> index a97eb44a9a87..eccaa176b6b9 100644
> --- a/rust/kernel/io.rs
> +++ b/rust/kernel/io.rs
> @@ -11,6 +11,7 @@
>  
>  pub mod mem;
>  pub mod poll;
> +pub mod register;
>  pub mod resource;
>  
>  pub use resource::Resource;
> diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
> new file mode 100644
> index 000000000000..e414aebe4c86
> --- /dev/null
> +++ b/rust/kernel/io/register.rs
> @@ -0,0 +1,1198 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! A macro to define register layout and accessors.
> +//!
> +//! A single register typically includes several fields, which are accessed through a combination
> +//! of bit-shift and mask operations that introduce a class of potential mistakes, notably because
> +//! not all possible field values are necessarily valid.
> +//!
> +//! The [`register!`] macro in this module provides an intuitive and readable syntax for defining a
> +//! dedicated type for each register. Each such type comes with its own field accessors that can
> +//! return an error if a field's value is invalid. Please look at the [`bitfield!`] macro for the
> +//! complete syntax of fields definitions.
> +//!
> +//! [`register!`]: kernel::register!
> +//! [`bitfield!`]: crate::bitfield!

Oops, I should remove these references to `bitfield!`...