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The SZ_* constants are usize, matching the CPU pointer width. But device address spaces have their own widths (32-bit MMIO windows, 64-bit GPU framebuffers, etc.), so drivers end up casting these constants with SZ_1M as u64 or helper functions. This adds boilerplate with no safety benefit. Add a SizeConstants trait with associated SZ_* constants, implemented for u32, u64, and usize. With the trait in scope, callers write u64::SZ_1M or u32::SZ_4K to get the constant in their device's native width. All SZ_* values fit in a u32, so every implementation is lossless. Each impl has a const assert to catch any future constant that would overflow. A define_sizes! macro generates everything from a single internal list of names. The macro takes the target types as arguments, so adding a new target type requires changing only the call site. Suggested-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/all/DGB9G697GSWO.3VBFGU5MKFPMR@kernel.org/ Link: https://lore.kernel.org/all/DGHI8WRKBQS9.38910L6FIIZTE@kernel.org/ Reviewed-by: Eliot Courtney <ecourtney@nvidia.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Acked-by: Gary Guo <gary@garyguo.net> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Link: https://patch.msgid.link/20260404021204.339779-2-jhubbard@nvidia.com [ Applied the "kernel vertical" imports style. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
134 lines
3.8 KiB
134 lines
3.8 KiB