[WIP RFC v2 25/35] rust: drm/kms: Add RawPlaneState::crtc()

[Lyude Paul]

Add a binding for checking drm_plane_state.crtc. Note that we don't have a
way of knowing what DriverCrtc implementation would be used here (and want
to make this function also available on OpaquePlaneState types), so we
return an OpaqueCrtc.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 rust/kernel/drm/kms/plane.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/rust/kernel/drm/kms/plane.rs b/rust/kernel/drm/kms/plane.rs
index 04f1bdfbb1ea2..4d16d53179fca 100644
--- a/rust/kernel/drm/kms/plane.rs
+++ b/rust/kernel/drm/kms/plane.rs
@@ -30,6 +30,7 @@
     ModeObject,
     StaticModeObject,
     atomic::*,
+    crtc::*,
 };
 
 /// The main trait for implementing the [`struct drm_plane`] API for [`Plane`]
@@ -489,6 +490,12 @@ fn plane(&self) -> &Self::Plane {
         // invariant throughout the lifetime of the Plane
         unsafe { Self::Plane::from_raw(self.as_raw().plane) }
     }
+
+    /// Return the current [`OpaqueCrtc`] assigned to this plane, if there is one.
+    fn crtc<'a, 'b: 'a>(&'a self) -> Option<&'b OpaqueCrtc<<Self::Plane as ModeObject>::Driver>> {
+        // SAFETY: This cast is guaranteed safe by `OpaqueCrtc`s invariants.
+        NonNull::new(self.as_raw().crtc).map(|c| unsafe { OpaqueCrtc::from_raw(c.as_ptr()) })
+    }
 }
 impl<T: AsRawPlaneState + ?Sized> RawPlaneState for T {}
 
-- 
2.46.1