[PATCH 02/10] rust: Add an Integer trait

[Remo Senekowitsch]

From: "Rob Herring (Arm)" <robh@xxxxxxxxxx>

Add an "Integer" trait similar to crate::num::Integer. This is useful
for implementing generic methods which operate on different sizes of
integers. One example is reading DT/ACPI firmware properties.

This was originally proposed by Alice Ryhl[1].

[1] https://lore.kernel.org/rust-for-linux/CAH5fLgiXPZqKpWSSNdx-Ww-E9h2tOLcF3_8Y4C_JQ0eU8EMwFw@xxxxxxxxxxxxxx/

Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Signed-off-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
---
 rust/kernel/types.rs | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 2bbaab83b..21647b7ba 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -3,10 +3,11 @@
 //! Kernel types.
 
 use crate::init::{self, PinInit};
+use crate::transmute::{AsBytes, FromBytes};
 use core::{
     cell::UnsafeCell,
     marker::{PhantomData, PhantomPinned},
-    mem::{ManuallyDrop, MaybeUninit},
+    mem::{size_of, ManuallyDrop, MaybeUninit},
     ops::{Deref, DerefMut},
     ptr::NonNull,
 };
@@ -553,6 +554,25 @@ pub enum Either<L, R> {
     Right(R),
 }
 
+/// Trait defined for all integer types similar to `crate::num::Integer`
+pub trait Integer: FromBytes + AsBytes + Copy {
+    /// Size of the integer in bytes
+    const SIZE: usize;
+}
+
+macro_rules! impl_int {
+    ($($typ:ty),* $(,)?) => {$(
+        impl Integer for $typ {
+            const SIZE: usize = size_of::<Self>();
+        }
+    )*};
+}
+
+impl_int! {
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+}
+
 /// Zero-sized type to mark types not [`Send`].
 ///
 /// Add this type as a field to your struct if your type should not be sent to a different task.
-- 
2.49.0