kernel/git/next/linux-next.git/rust/macros/io, branch master

rust: io: register: unify handling of register with/without bitfields

2026-09-06T11:39:49+00:00

Move the `FixedRegister` from a property of register to become a property of type. Name the new trait `FixedIoLoc` indicating if I/O location of a type is unique for a specific base. Thus, bitfields become just a special case of this (where type is unique because we're generating it in the register macro), and expose feature to registers without inline bitfield definition with the `#[unique]` attribute. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-16-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: remove `Register` trait and cleanup macro

2026-09-06T11:39:49+00:00

With the removal of relative registers, there are only two type of registers left, fixed register and register arrays. There is not much benefit in having a common super trait for them anymore, thus remove it, and cleanup the macro rules associated with it. Signed-off-by: Gary Guo Reviewed-by: Alexandre Courbot Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-15-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: remove relative registers

2026-09-06T11:39:49+00:00

Relative registers can be better served by projection to subregion instead of ad-hoc handling in register macro. Projection composes better (e.g. it natively allows relative registers of relative registers without needing additional support). Remove relative register support, and update the documentation to demonstrate how projection and subregions can be used to achieve this instead. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-14-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: support fixed offset register without bitfield

2026-09-06T11:39:49+00:00

Add a rule to allow creating `IoLoc` in `register!()` using an existing type and not create a bitfield. Add an example to demonstrate this for FIFO registers. This rule is also going to be used to create subregions for registers; the example of doing so will be added later when relative registers are removed. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-11-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: make register have a typed base

2026-09-06T11:39:49+00:00

Previously `register!` defined registers can be used on any untyped I/O regions. With all users specifying their desired register type now, propagate the specified type and restrict I/O access only when type matches. Also, add an `io_project!` example which is enabled by this change. Signed-off-by: Gary Guo Reviewed-by: Alexandre Courbot Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-10-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: allow explicit base type specification

2026-09-06T11:39:48+00:00

Currently registers work for all untyped I/O regions, which is not ideal. It allows registers defined for device A to work for another device B and there is no safeguarding at all. All users of the `register!` macro know what type it will be operating on, and that type is consistent across the driver. Therefore, add a `base` parameter to `register!`. Currently this parameter is unused in the generated code; it will be used when all users of `register!` is converted to gain the parameter. Signed-off-by: Gary Guo Reviewed-by: Alexandre Courbot Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-6-5552b1d59525@garyguo.net [ Remove unnecessary #[allow(unused)] from the 'base' field. - Danilo ] Signed-off-by: Danilo Krummrich

rust: io: perform conversions using `AsRepr`

2026-09-06T11:39:48+00:00

For types that are layout-compatible with an I/O capable type, we would want the ability to use them directly for I/O operations. E.g. bitfield! { pub struct Foo(u32) { ... } } #[repr(C)] struct Bar { foo: Foo, } let mmio: Mmio<'_, Bar> = ...; io_read!(mmio, .foo) Currently this feature is available from `register!()` macro but not otherwise available with `io_read!`, `io_write!`. Support this by performing conversions to I/O primitives via the `AsRepr`/`AsReprMut` trait. This makes the `IoLoc::IoType` and `Register::Storage` redundant; thus remove them; also convert register methods to use the `read_val` and `write_val` instead. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-4-5552b1d59525@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: register: reimplement as proc macro

2026-09-03T18:25:54+00:00

The existing `register!` macro is implemented as a declarative macro. Reimplement it as proc macro instead, with no functional changes intended. The old implementation produces unhelpful diagnostics when things go wrong. For example, for code like register! { pub(crate) TESTREG(u32) { 31:0 data; } } which misses out the "@ offset" part of the specification, and the following error is produced: error: no rules expected `{` --> test.rs:42:5 | 42 | / register! { 43 | | pub(crate) TESTREG(u32) { 44 | | 31:0 data; ... | 100 | | } | |_____^ no rules expected this token in macro call which isn't very helpful. With the proc macro implementation, the following error is produced: error: expected `@` or `=>` --> tests.rs:43:33 | 43 | pub(crate) TESTREG(u32) { | ^ which is much more helpful. Apart from diagnostics, proc macro also has a benefit of not having follow-set restrictions, which makes syntax like register!(name: ty @ offset); possible; declarative macro will reject this as `@` is not in the follow-set of "ty" metavariable kind. Signed-off-by: Gary Guo Reviewed-by: Alexandre Courbot Tested-by: Alexandre Courbot Link: https://patch.msgid.link/20260901-typed_register-v4-1-5552b1d59525@garyguo.net [ Fix typo in module-level doc comment and fix ArrayDef syntax description to match the actual macro syntax. - Danilo ] Signed-off-by: Danilo Krummrich