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

rust: io: introduce `write_reg` and `LocatedRegister`

2026-03-17T19:04:11+00:00

Some I/O types, like fixed address registers, carry their location
alongside their values. For these types, the regular `Io::write` method
can lead into repeating the location information twice: once to provide
the location itself, another time to build the value.

We are also considering supporting making all register values carry
their full location information for convenience and safety.

Add a new `Io::write_reg` method that takes a single argument
implementing `LocatedRegister`, a trait that decomposes implementors
into a `(location, value)` tuple. This allows write operations on fixed
offset registers to be done while specifying their name only once.

Suggested-by: Danilo Krummrich 
Link: https://lore.kernel.org/all/DH0XBLXZD81K.22SWIZ1ZAOW1@kernel.org/
Signed-off-by: Alexandre Courbot 
Link: https://patch.msgid.link/20260314-register-v9-8-86805b2f7e9d@nvidia.com
[ Replace FIFO with VERSION register in the examples. - Danilo ]
Signed-off-by: Danilo Krummrich

rust: io: add `register!` macro

2026-03-17T19:04:11+00:00

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.

Suggested-by: Danilo Krummrich 
Link: https://lore.kernel.org/all/20250306222336.23482-6-dakr@kernel.org/
Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Signed-off-by: Alexandre Courbot 
Link: https://patch.msgid.link/20260314-register-v9-7-86805b2f7e9d@nvidia.com
[ * Improve wording and formatting of doc-comments,
  * Import build_assert!(),
  * Add missing inline annotations,
  * Call static_assert!() with absolute path,
  * Use expect instead of allow.

    - Danilo ]
Signed-off-by: Danilo Krummrich

rust: io: mem: use non-relaxed I/O ops in examples

2026-03-17T19:02:09+00:00

The `_relaxed` I/O variant methods are about to be replaced by a wrapper
type exposing this access pattern with the regular methods of the `Io`
trait. Thus replace the examples to use the regular I/O methods.

Since these are examples, we want them to use the most standard ops
anyway, and the relaxed variants were but an addition that was
MMIO-specific.

Reviewed-by: Daniel Almeida 
Acked-by: Alice Ryhl 
Signed-off-by: Alexandre Courbot 
Reviewed-by: Gary Guo 
Link: https://patch.msgid.link/20260206-io-v2-2-71dea20a06e6@nvidia.com
Signed-off-by: Danilo Krummrich

Merge tag 'v6.19-rc7' into driver-core-next

2026-01-26T12:23:52+00:00

We need the driver-core fixes in here as well to build on top of.

Signed-off-by: Danilo Krummrich

rust: io: separate generic I/O helpers from MMIO implementation

2026-01-23T20:20:11+00:00

The previous Io 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: 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 type that
implements the Io traits. Rename IoRaw to MmioRaw and update consumers to
use the new types.

Cc: Alexandre Courbot 
Cc: Alice Ryhl 
Cc: Bjorn Helgaas 
Cc: Gary Guo 
Cc: Danilo Krummrich 
Cc: John Hubbard 
Signed-off-by: Zhi Wang 
Reviewed-by: Alice Ryhl 
Reviewed-by: Alexandre Courbot 
Reviewed-by: Gary Guo 
Link: https://patch.msgid.link/20260121202212.4438-3-zhiw@nvidia.com
[ Add #[expect(unused)] to define_{read,write}!(). - Danilo ]
Signed-off-by: Danilo Krummrich

rust: io: always inline functions using build_assert with arguments

2026-01-14T19:30:26+00:00

`build_assert` relies on the compiler to optimize out its error path.
Functions using it with its arguments must thus always be inlined,
otherwise the error path of `build_assert` might not be optimized out,
triggering a build error.

Cc: stable@vger.kernel.org
Fixes: ce30d94e6855 ("rust: add `io::{Io, IoRaw}` base types")
Reviewed-by: Daniel Almeida 
Signed-off-by: Alexandre Courbot 
Tested-by: Timur Tabi 
Link: https://patch.msgid.link/20251208-io-build-assert-v3-2-98aded02c1ea@nvidia.com
Signed-off-by: Danilo Krummrich

rust: io: replace `kernel::c_str!` with C-Strings

2025-12-22T16:30:31+00:00

C-String literals were added in Rust 1.77. Replace instances of
`kernel::c_str!` with C-String literals where possible.

Signed-off-by: Tamir Duberstein 
Reviewed-by: Daniel Almeida 
Link: https://patch.msgid.link/20251222-cstr-driver-core-v1-4-1142a177d0fd@gmail.com
[ Use kernel vertical import style. - Danilo ]
Signed-off-by: Danilo Krummrich

rust: io: add typedef for phys_addr_t

2025-11-13T09:17:24+00:00

The C typedef phys_addr_t is missing an analogue in Rust, meaning that
we end up using bindings::phys_addr_t or ResourceSize as a replacement
in various places throughout the kernel. Fix that by introducing a new
typedef on the Rust side. Place it next to the existing ResourceSize
typedef since they're quite related to each other.

Cc: stable@vger.kernel.org # for v6.18 [1]
Signed-off-by: Alice Ryhl 
Link: https://patch.msgid.link/20251112-resource-phys-typedefs-v2-4-538307384f82@google.com
Link: https://lore.kernel.org/all/20251112-resource-phys-typedefs-v2-0-538307384f82@google.com/ [1]
Signed-off-by: Danilo Krummrich

rust: io: move ResourceSize to top-level io module

2025-11-13T09:16:51+00:00

Resource sizes are a general concept for dealing with physical
addresses, and not specific to the Resource type, which is just one way
to access physical addresses. Thus, move the typedef to the io module.

Still keep a re-export under resource. This avoids this commit from
being a flag-day, but I also think it's a useful re-export in general so
that you can import

	use kernel::io::resource::{Resource, ResourceSize};

instead of having to write

	use kernel::io::{
	    resource::Resource,
	    ResourceSize,
	};

in the specific cases where you need ResourceSize because you are using
the Resource type. Therefore I think it makes sense to keep this
re-export indefinitely and it is *not* intended as a temporary re-export
for migration purposes.

Cc: stable@vger.kernel.org # for v6.18 [1]
Signed-off-by: Alice Ryhl 
Link: https://patch.msgid.link/20251112-resource-phys-typedefs-v2-2-538307384f82@google.com
Link: https://lore.kernel.org/all/20251112-resource-phys-typedefs-v2-0-538307384f82@google.com/ [1]
Signed-off-by: Danilo Krummrich

rust: io: define ResourceSize as resource_size_t

2025-11-13T08:58:24+00:00

These typedefs are always equivalent so this should not change anything,
but the code makes a lot more sense like this.

Cc: stable@vger.kernel.org
Signed-off-by: Alice Ryhl 
Fixes: 493fc33ec252 ("rust: io: add resource abstraction")
Link: https://patch.msgid.link/20251112-resource-phys-typedefs-v2-1-538307384f82@google.com
Signed-off-by: Danilo Krummrich