[RFC v2 07/13] rust: sync: atomic: Add Atomic<u{32,64}>

[Boqun Feng]

Add generic atomic support for basic unsigned types that have an
`AtomicIpml` with the same size and alignment.

Signed-off-by: Boqun Feng <boqun.feng at gmail.com>
---
 rust/kernel/sync/atomic.rs | 80 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
index b791abc59b61..b2e81e22c105 100644
--- a/rust/kernel/sync/atomic.rs
+++ b/rust/kernel/sync/atomic.rs
@@ -22,3 +22,83 @@
 
 pub use generic::Atomic;
 pub use ordering::{Acquire, Full, Relaxed, Release};
+
+/// ```rust
+/// use kernel::sync::atomic::{Atomic, Relaxed};
+///
+/// let x = Atomic::new(42u64);
+///
+/// assert_eq!(42, x.load(Relaxed));
+/// ```
+// SAFETY: `u64` and `i64` has the same size and alignment.
+unsafe impl generic::AllowAtomic for u64 {
+    type Repr = i64;
+
+    fn into_repr(self) -> Self::Repr {
+        self as _
+    }
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        repr as _
+    }
+}
+
+/// ```rust
+/// use kernel::sync::atomic::{Atomic, Full, Relaxed};
+///
+/// let x = Atomic::new(42u64);
+///
+/// assert_eq!(42, x.fetch_add(12, Full));
+/// assert_eq!(54, x.load(Relaxed));
+///
+/// x.add(13, Relaxed);
+///
+/// assert_eq!(67, x.load(Relaxed));
+/// ```
+impl generic::AllowAtomicArithmetic for u64 {
+    type Delta = u64;
+
+    fn delta_into_repr(d: Self::Delta) -> Self::Repr {
+        d as _
+    }
+}
+
+/// ```rust
+/// use kernel::sync::atomic::{Atomic, Relaxed};
+///
+/// let x = Atomic::new(42u32);
+///
+/// assert_eq!(42, x.load(Relaxed));
+/// ```
+// SAFETY: `u32` and `i32` has the same size and alignment.
+unsafe impl generic::AllowAtomic for u32 {
+    type Repr = i32;
+
+    fn into_repr(self) -> Self::Repr {
+        self as _
+    }
+
+    fn from_repr(repr: Self::Repr) -> Self {
+        repr as _
+    }
+}
+
+/// ```rust
+/// use kernel::sync::atomic::{Atomic, Full, Relaxed};
+///
+/// let x = Atomic::new(42u32);
+///
+/// assert_eq!(42, x.fetch_add(12, Full));
+/// assert_eq!(54, x.load(Relaxed));
+///
+/// x.add(13, Relaxed);
+///
+/// assert_eq!(67, x.load(Relaxed));
+/// ```
+impl generic::AllowAtomicArithmetic for u32 {
+    type Delta = u32;
+
+    fn delta_into_repr(d: Self::Delta) -> Self::Repr {
+        d as _
+    }
+}
-- 
2.45.2