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2026-01-23rust: io: separate generic I/O helpers from MMIO implementationZhi Wang
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> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Gary Guo <gary@garyguo.net> Link: https://patch.msgid.link/20260121202212.4438-3-zhiw@nvidia.com [ Add #[expect(unused)] to define_{read,write}!(). - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2025-11-11rust: io: cleanup imports and use "kernel vertical" styleDanilo Krummrich
Commit 46f045db5a94 ("rust: Add read_poll_timeout_atomic function") initiated the first import change in the I/O module using the agreed "kernel vertical" import style [1]. For consistency throughout the module, adjust all other imports accordingly. While at it, drop unnecessary imports covered by prelude::*. Link: https://docs.kernel.org/rust/coding-guidelines.html#imports [1] Reviewed-by: Zhi Wang <zhiw@nvidia.com> Link: https://patch.msgid.link/20251104133301.59402-1-dakr@kernel.org [ Use prelude::* in io/poll.rs. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2025-11-04rust: Add read_poll_timeout_atomic functionFUJITA Tomonori
Add read_poll_timeout_atomic function which polls periodically until a condition is met, an error occurs, or the attempt limit is reached. The C's read_poll_timeout_atomic() is used for the similar purpose. In atomic context the timekeeping infrastructure is unavailable, so reliable time-based timeouts cannot be implemented. So instead, the helper accepts a maximum number of attempts and busy-waits (udelay + cpu_relax) between tries. Reviewed-by: Alice Ryhl <aliceryhl@google.com> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> Link: https://patch.msgid.link/20251103112958.2961517-3-fujita.tomonori@gmail.com [ Adjust imports to use "kernel vertical" style. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2025-10-26rust: simplify read_poll_timeout's example codeFUJITA Tomonori
- Drop unnecessary Result's '<()>' - Use '?' instead of match Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2025-08-21rust: Add read_poll_timeout functionFUJITA Tomonori
Add read_poll_timeout function which polls periodically until a condition is met, an error occurs, or the timeout is reached. The C's read_poll_timeout (include/linux/iopoll.h) is a complicated macro and a simple wrapper for Rust doesn't work. So this implements the same functionality in Rust. The C version uses usleep_range() while the Rust version uses fsleep(), which uses the best sleep method so it works with spans that usleep_range() doesn't work nicely with. The sleep_before_read argument isn't supported since there is no user for now. It's rarely used in the C version. Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Fiona Behrens <me@kloenk.dev> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Tested-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com> Tested-by: Daniel Almeida <daniel.almeida@collabora.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> Link: https://lore.kernel.org/r/20250821002055.3654160-3-fujita.tomonori@gmail.com [ Fix a minor typo and add missing backticks. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>