rust: io: perform conversions using `AsRepr`

For types that are layout-compatible with an I/O capable type, we would
want the ability to use them directly for I/O operations. E.g.

    bitfield! {
        pub struct Foo(u32) {
            ...
        }
    }

    #[repr(C)]
    struct Bar {
        foo: Foo,
    }

    let mmio: Mmio<'_, Bar> = ...;
    io_read!(mmio, .foo)

Currently this feature is available from `register!()` macro but not
otherwise available with `io_read!`, `io_write!`. Support this by
performing conversions to I/O primitives via the `AsRepr`/`AsReprMut`
trait.

This makes the `IoLoc::IoType` and `Register::Storage` redundant; thus
remove them; also convert register methods to use the `read_val` and
`write_val` instead.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260901-typed_register-v4-4-5552b1d59525@garyguo.net
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 0 insertions, 15 deletions

diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
index 6a19552ffb95..45d2e73a92e7 100644
--- a/rust/kernel/io/register.rs
+++ b/rust/kernel/io/register.rs
@@ -117,9 +117,6 @@ use super::Region;
 
 /// Trait implemented by all registers.
 pub trait Register: Sized {
-    /// Backing primitive type of the register.
-    type Storage: Into<Self> + From<Self>;
-
     /// Start offset of the register.
     ///
     /// The interpretation of this offset depends on the type of the register.
@@ -135,8 +132,6 @@ impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for ()
 where
     T: FixedRegister,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         T::OFFSET
@@ -149,8 +144,6 @@ impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for T
 where
     T: FixedRegister,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         T::OFFSET
@@ -174,8 +167,6 @@ impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for FixedRegisterLoc<T>
 where
     T: FixedRegister,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         T::OFFSET
@@ -246,8 +237,6 @@ where
     T: RelativeRegister,
     B: RegisterBase<T::BaseFamily> + ?Sized,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         RelativeRegisterLoc::offset(self)
@@ -289,8 +278,6 @@ impl<const SIZE: usize, T> IoLoc<Region<SIZE>, T> for RegisterArrayLoc<T>
 where
     T: RegisterArray,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         T::OFFSET + self.0 * T::STRIDE
@@ -377,8 +364,6 @@ where
     T: RelativeRegisterArray,
     B: RegisterBase<T::BaseFamily> + ?Sized,
 {
-    type IoType = T::Storage;
-
     #[inline(always)]
     fn offset(self) -> usize {
         self.0.offset() + self.1 * T::STRIDE