rust: io: restrict untyped IO access and `register!` to `Region`

Currently the `Io` trait exposes a bunch of untyped IO accesses, but if the
`Io` region itself is typed, then it might be weird to have

    let io: Mmio<u32> = /* ... */;
    io.read8(1);

while not unsound, it is surely strange. Thus, restrict the untyped methods
and also the register macro to `Region` type only.

Implement it by adding a generic type to `IoLoc` indicating allowed base
types. This also paves the way to add typed register blocks in the future;
for example, we could use this mechanism to block driver A's `register!()`
generated macro from being used on driver B's MMIO. The same mechanism
could be used for relative IO registers. These are future opportunities,
and for now restrict everything to require `IoLoc<Region<SIZE>, _>`.

Suggested-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/rust-for-linux/DHLB3RO3OSF5.2R7F27U99BKLN@nvidia.com/
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://patch.msgid.link/20260706-io_projection-v6-3-72cd5d055d54@garyguo.net
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

0 files changed, 0 insertions, 0 deletions