linux.git/rust/kernel/io, branch master

rust: io: register: use path fragment for alias destination

2026-08-03T20:30:32+00:00

The destination of an alias is always another register, i.e. a `struct` type. Replace the `ident` fragment with a `path` one in the internal rules: `path` is more accurate, and allows referencing registers using a qualified path instead of only identifiers visible from the current module. This covers all aliases, except the relative register ones which are to be removed soon. The public rule cannot be updated yet because a `+` can still be matched after the alias; add a TODO item to update it after relative registers are removed. Signed-off-by: Alexandre Courbot Link: https://patch.msgid.link/20260724-registers_fix-v2-3-a0fb58b02185@nvidia.com Signed-off-by: Danilo Krummrich

rust: io: register: remove unused rule arguments

2026-08-03T20:30:32+00:00

A few arguments passed to internal rules are never used and just add unneeded complexity. Remove them to simplify the rules a bit. Signed-off-by: Alexandre Courbot Link: https://patch.msgid.link/20260724-registers_fix-v2-2-a0fb58b02185@nvidia.com Signed-off-by: Danilo Krummrich

rust: io: register: dispatch shortcut rules internally

2026-08-03T20:30:32+00:00

A couple of shortcut rules redispatch an already normalized declaration through the public register! entry point. This is unneeded - the public rule should only be invoked by users. Dispatch directly to the appropriate internal @reg rule instead. Signed-off-by: Alexandre Courbot Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260724-registers_fix-v2-1-a0fb58b02185@nvidia.com Signed-off-by: Danilo Krummrich

Merge patch series "rust: I/O type generalization and projection"

2026-07-13T21:50:39+00:00

Gary Guo says: This series presents a major rework of I/O types, as a summary: - Make I/O regions typed. The existing untyped region still exists with a dynamically sized `Region` type. - Create I/O view types to represent subregion of a full I/O region mapped. A projection macro is added to allow safely create such subviews. - Split I/O traits, make I/O views play a central role, avoid duplicate monomorphization and less `unsafe` code. - Add a `SysMem` backend, and make `Coherent` implement `Io`. - Add copying methods (memcpy_{from,to}io and friends). This series generalize `Mmio` type from just an untyped region to typed representations (so `MmioRaw` is `__iomem *T`). This allows us to remove the `IoKnownSize` trait; the information is sourced from just the pointer from the `KnownSize` trait instead. Building on top of that, `Mmio` and `ConfigSpace` have been converted to typed views of I/O regions rather than just a big chunk of untyped I/O memory. These changes made it possible to implement `Io` trait for `Coherent`. Shared system memory, `SysMem` is also added to the series, given it similarity in implementation compared to `Coherent`. In fact, the series use `SysMem` to implement `Coherent`'s I/O methods. Built on these generalization, this series add `io_project!()`. `io_project!()` performs a safe way to project a bigger view to a small subviews, and some Nova code has been converted in this series to demonstrate cleanups possible with this addition. New `io_read!()`, `io_write!()` has been added that supersedes `dma_read!()`, `dma_write!()` macro. Although, they work for primitives only (to be exact, types that the backend is `IoCapable` of). One feature that was lost from the old `dma_read!()` and `dma_write!()` series was the ability to read/write a large structs. However, the semantics was unclear to begin with, as there was no guarantee about their atomicity even for structs that were small enough to fit in u32. Suggested-by: Danilo Krummrich Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/near/571198078 Link: https://patch.msgid.link/20260706-io_projection-v6-0-72cd5d055d54@garyguo.net Signed-off-by: Danilo Krummrich

Merge patch series "ForLt/CovariantForLt split, auxiliary closure API and DevresLt"

2026-07-13T21:34:30+00:00

Danilo Krummrich says: The ForLt trait currently guarantees covariance, which allows safe lifetime shortening via cast_ref(). However, some types (e.g. those containing Mutex<&'bound T>) are invariant over their lifetime parameter and cannot safely use cast_ref(). This series splits ForLt into two traits: - ForLt: base trait for all lifetime-parameterized types, providing only the Of<'a> GAT. - CovariantForLt: unsafe subtrait that guarantees covariance, providing a safe cast_ref() method. For invariant types, a closure-based API (registration_data_with()) is added to the auxiliary subsystem. The closure's HRTB prevents the caller from choosing a concrete lifetime, which would be unsound for invariant types. On top of that, this series adds DevresLt, a thin wrapper around Devres> that shortens the stored 'static lifetime back to the caller's borrow scope. DevresLt provides both closure-based access (access_with/try_access_with for ForLt types) and direct reference access (access/try_access for CovariantForLt types). Also implement ForLt and CovariantForLt for Bar, IoMem and ExclusiveIoMem, and update their into_devres() methods to return DevresLt. Provide convenience type aliases DevresBar, DevresIoMem and DevresExclusiveIoMem. Link: https://patch.msgid.link/20260626183630.2585057-1-dakr@kernel.org Signed-off-by: Danilo Krummrich

rust: io: mem: return DevresLt from IoMem/ExclusiveIoMem::into_devres()

2026-07-11T17:47:00+00:00

Implement ForLt and CovariantForLt for IoMem<'static, SIZE> and ExclusiveIoMem<'static, SIZE> so that DevresLt can shorten the stored 'static lifetime back to the caller's borrow lifetime. CovariantForLt is sound because both types only hold &'a Device, which is covariant over 'a. Since DevresLt::new() handles the lifetime transmutation internally, into_devres() no longer needs an explicit transmute to 'static. Add DevresIoMem and DevresExclusiveIoMem type aliases. Reviewed-by: Alexandre Courbot Link: https://patch.msgid.link/20260626183630.2585057-8-dakr@kernel.org [ Add default SIZE parameter to DevresIoMem. - Danilo ] Signed-off-by: Danilo Krummrich

rust: io: move `Io` methods to extension trait

2026-07-11T16:07:41+00:00

`Io` trait now has a single required method with many more provided methods. Provided methods may want to rely on their implementations to not be arbitrarily overridden by implementers for correctness or soundness. A good example is the `size` method, it may be relied by unsafe code and thus must be consistent with the metadata obtained from `as_ptr`. Thus, create a new trait to host `size` method, extract existing provided methods to the new trait, and provide a blanket implementation. This pattern is used extensively in userspace Rust libraries e.g. `tokio` where `AsyncRead` has minimum methods and `AsyncReadExt` is what users mostly interact with. To avoid changing all user imports, the base trait is renamed to `IoBase` and the newly added trait takes the existing `Io` name. Reviewed-by: Alexandre Courbot Suggested-by: Danilo Krummrich Signed-off-by: Gary Guo Reviewed-by: Daniel Almeida Link: https://patch.msgid.link/20260706-io_projection-v6-12-72cd5d055d54@garyguo.net [ Add comment explaining the purpose of the Io blanket implementation. - Danilo ] Signed-off-by: Danilo Krummrich

rust: io: remove `MmioOwned`

2026-07-11T16:00:12+00:00

`Io` trait is now very easy to implement. Thus, implement it on `Bar` and `IoMem` directly and remove the `MmioOwned` struct. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Reviewed-by: Daniel Almeida Suggested-by: Danilo Krummrich Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/near/571198078 Link: https://patch.msgid.link/20260706-io_projection-v6-11-72cd5d055d54@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: implement `Mmio` as view type

2026-07-11T15:59:32+00:00

Implement `Mmio` as view type and convert `RelaxedMmio` to view type as well. I/O implementations of `MmioOwned` are changed to delegate to the `Mmio` view type. All existing users of `MmioOwned` in the documentation which do not actually reflect the owning semantics is converted. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Tested-by: Daniel Almeida Reviewed-by: Daniel Almeida Link: https://patch.msgid.link/20260706-io_projection-v6-7-72cd5d055d54@garyguo.net Signed-off-by: Danilo Krummrich

rust: io: rename `Mmio` to `MmioOwned`

2026-07-11T15:59:32+00:00

Most users would more commonly reach out to a view of `Mmio` rather than an owned instance of `Mmio`. Only implementor of `Io` like `Bar` or `IoMem` would need the owned version. Thus, rename `Mmio` to `MmioOwned` so that the name `Mmio` can be used for the view type instead. Reviewed-by: Alexandre Courbot Signed-off-by: Gary Guo Reviewed-by: Daniel Almeida Suggested-by: Danilo Krummrich Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/near/571198078 Link: https://patch.msgid.link/20260706-io_projection-v6-6-72cd5d055d54@garyguo.net Signed-off-by: Danilo Krummrich