linux-kernel - [RFC v3 13/33] rust: drm/kms: Add RawPlane and RawPlaneState

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Message-ID: <20250305230406.567126-14-lyude@redhat.com>
Date: Wed,  5 Mar 2025 17:59:29 -0500
From: Lyude Paul <lyude@...hat.com>
To: dri-devel@...ts.freedesktop.org,
	rust-for-linux@...r.kernel.org
Cc: Danilo Krummrich <dakr@...nel.org>,
	mcanal@...lia.com,
	Alice Ryhl <aliceryhl@...gle.com>,
	Maxime Ripard <mripard@...nel.org>,
	Simona Vetter <sima@...ll.ch>,
	Daniel Almeida <daniel.almeida@...labora.com>,
	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>,
	Trevor Gross <tmgross@...ch.edu>,
	linux-kernel@...r.kernel.org (open list)
Subject: [RFC v3 13/33] rust: drm/kms: Add RawPlane and RawPlaneState

Same thing as RawCrtc and RawCrtcState, but for DRM planes now

Signed-off-by: Lyude Paul <lyude@...hat.com>

---

V3:
* Limit unsafe scope in RawPlane::index()
* Improve safety comments

Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 rust/kernel/drm/kms/plane.rs | 37 ++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/rust/kernel/drm/kms/plane.rs b/rust/kernel/drm/kms/plane.rs
index 9f262156eac6c..d1fabdf42df54 100644
--- a/rust/kernel/drm/kms/plane.rs
+++ b/rust/kernel/drm/kms/plane.rs
@@ -373,6 +373,29 @@ pub unsafe trait ModesettablePlane: AsRawPlane {
     type State: FromRawPlaneState;
 }
 
+/// Common methods available on any type which implements [`AsRawPlane`].
+///
+/// This is implemented internally by DRM, and provides many of the basic methods for working with
+/// planes.
+pub trait RawPlane: AsRawPlane {
+    /// Return the index of this DRM plane
+    #[inline]
+    fn index(&self) -> u32 {
+        // SAFETY:
+        // - The index is initialized by the time we expose planes to users, and does not change
+        //   throughout its lifetime
+        // - `.as_raw()` always returns a valid poiinter.
+        unsafe { *self.as_raw() }.index
+    }
+
+    /// Return the index of this DRM plane in the form of a bitmask
+    #[inline]
+    fn mask(&self) -> u32 {
+        1 << self.index()
+    }
+}
+impl<T: AsRawPlane> RawPlane for T {}
+
 /// A trait implemented by any type which can produce a reference to a [`struct drm_plane_state`].
 ///
 /// This is implemented internally by DRM.
@@ -436,6 +459,20 @@ pub trait FromRawPlaneState: AsRawPlaneState {
     unsafe fn from_raw_mut<'a>(ptr: *mut bindings::drm_plane_state) -> &'a mut Self;
 }
 
+/// Common methods available on any type which implements [`AsRawPlane`].
+///
+/// This is implemented internally by DRM, and provides many of the basic methods for working with
+/// the atomic state of [`Plane`]s.
+pub trait RawPlaneState: AsRawPlaneState {
+    /// Return the plane that this plane state belongs to.
+    fn plane(&self) -> &Self::Plane {
+        // SAFETY: The index is initialized by the time we expose Plane objects to users, and is
+        // invariant throughout the lifetime of the Plane
+        unsafe { Self::Plane::from_raw(self.as_raw().plane) }
+    }
+}
+impl<T: AsRawPlaneState + ?Sized> RawPlaneState for T {}
+
 /// The main interface for a [`struct drm_plane_state`].
 ///
 /// This type is the main interface for dealing with the atomic state of DRM planes. In addition, it
-- 
2.48.1