linux-kernel - [PATCH v3 15/19] rust: num: Add an upward alignment helper for usize

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Message-Id: <20250507-nova-frts-v3-15-fcb02749754d@nvidia.com>
Date: Wed, 07 May 2025 22:52:42 +0900
From: Alexandre Courbot <acourbot@...dia.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <benno.lossin@...ton.me>, 
 Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
 Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 Jonathan Corbet <corbet@....net>
Cc: John Hubbard <jhubbard@...dia.com>, Ben Skeggs <bskeggs@...dia.com>, 
 Joel Fernandes <joelagnelf@...dia.com>, Timur Tabi <ttabi@...dia.com>, 
 Alistair Popple <apopple@...dia.com>, linux-kernel@...r.kernel.org, 
 rust-for-linux@...r.kernel.org, nouveau@...ts.freedesktop.org, 
 dri-devel@...ts.freedesktop.org, Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH v3 15/19] rust: num: Add an upward alignment helper for
 usize

From: Joel Fernandes <joelagnelf@...dia.com>

This will be used in the nova-core driver where we need to upward-align
the image size to get to the next image in the VBIOS ROM.

[acourbot@...dia.com: handled conflicts due to removal of patch creating
num.rs]

Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
---
 rust/kernel/lib.rs |  1 +
 rust/kernel/num.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index ab0286857061d2de1be0279cbd2cd3490e5a48c3..be75b196aa7a29cf3eed7c902ed8fb98689bbb50 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -67,6 +67,7 @@
 pub mod miscdevice;
 #[cfg(CONFIG_NET)]
 pub mod net;
+pub mod num;
 pub mod of;
 pub mod page;
 #[cfg(CONFIG_PCI)]
diff --git a/rust/kernel/num.rs b/rust/kernel/num.rs
new file mode 100644
index 0000000000000000000000000000000000000000..7d69cbd957546ab75fcf677b851f102c3a5e5c39
--- /dev/null
+++ b/rust/kernel/num.rs
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Numerical and binary utilities for primitive types.
+
+/// A trait providing alignment operations for `usize`.
+use core::ops::{Add, BitAnd, BitOr, Not, Sub};
+
+/// Traits for unsigned integers
+pub trait Unsigned:
+    Copy
+    + BitAnd<Output = Self>
+    + BitOr<Output = Self>
+    + Not<Output = Self>
+    + Add<Output = Self>
+    + Sub<Output = Self>
+    + From<u8>
+{
+}
+
+macro_rules! unsigned_trait_impl {
+    ($($t:ty),+) => {
+        $(
+            impl Unsigned for $t {}
+        )+
+    };
+}
+unsigned_trait_impl!(usize, u8, u16, u32, u64, u128);
+
+/// Trait for unsigned integer alignment
+pub trait NumAlign {
+    /// Implement upward power-of-2 alignment for unsigned ints
+    fn align_up(self, alignment: Self) -> Self;
+}
+
+impl<T> NumAlign for T
+where
+    T: Unsigned,
+{
+    #[inline]
+    fn align_up(self, alignment: Self) -> Self {
+        let one = T::from(1u8);
+        (self + alignment - one) & !(alignment - one)
+    }
+}

-- 
2.49.0