DMA: implement a `dma::Range` type

[dakr]

Currently the dma::Coherent API provides the DmaAddress type as a typedef (type DmaAddress = bindings::dma_addr_t) only. The base address is handed out as a bare integer, so any offset arithmetic a driver does on it is unchecked.

Add a dma::Range type that couples a base dma::Address with a length and only hands out addresses and sub-ranges provably within [base, base + len). All arithmetic must be checked against both the length and overflow of the underlying dma_addr_t.

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This requires submitting a proper patch to the corresponding Linux kernel mailing lists. Please remember to test your changes (including generating the documentation if changed, running the Rust doctests if changed, etc.), use a proper title for the commit, sign your commit under the Developer's Certificate of Origin and add a Suggested-by: and Link: tags to this issue. Please see https://docs.kernel.org/process/submitting-patches.html and https://rust-for-linux.com/contributing for details.

[blitzRahul]

Sounds like a fun first issue to me, working on it.

[vasilisalmpanis]

Hello, I posted my patch
https://lore.kernel.org/rust-for-linux/20260806-dma-v1-1-e8a39327c7f5@gmail.com/T/#u
Any suggestions are welcome

[vasilisalmpanis]

Hi @dakr, after reading recent messages in the list, its unclear to me if this issue should remain open.
I'm talking about Gary's comment about IO projections in https://lore.kernel.org/rust-for-linux/20260806212503.3119449-1-dakr@kernel.org/T/#m6cae4bc52ce9f502905464e763ac7490c166c54c
Should I continue working on it and send v2 or its not necessary anymore?