rust: dma: add generalized container for types other than slices

Currently, `CoherentAllocation` is concecptually a DMA coherent container
of a slice of `[T]` of runtime-checked length. Generalize it by creating
`dma::Coherent<T>` which can hold any value of `T`.
`Coherent::alloc_with_attrs` is implemented but not yet exposed, as I
believe we should not expose the way to obtain an uninitialized coherent
region.

`Coherent<[T]>` provides a `len` method instead of the previous `count()`
method to be consistent with methods on slices.

The existing type is re-defined as a type alias of `Coherent<[T]>` to ease
transition. Methods in use are not yet removed.

Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260320194626.36263-3-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Gary Guo 2026-03-20 20:45:37 +01:00 • committed by Danilo Krummrich
commit d9aee73c56
2 changed files with 226 additions and 139 deletions