[PATCH 2/2] rust: kernel: of: Add overlay id abstraction

[Ayush Singh <ayush@beagleboard.org>]

Allow applying devicetree overlays from Rust.

The overlay is removed on Drop.

Signed-off-by: Ayush Singh <ayush@beagleboard.org>
---
 rust/kernel/of.rs | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
index db4ec26ff7de024f5e513a2223cfd841f57b1434..76dbb118d2dc21d1174e0a1ca8f8610d1d176119 100644
--- a/rust/kernel/of.rs
+++ b/rust/kernel/of.rs
@@ -80,3 +80,32 @@ pub fn as_raw(&self) -> *mut bindings::device_node {
         self.0.get()
     }
 }
+
+/// Devicetree overlay present in livetree.
+///
+/// The overlay is removed on Drop
+pub struct OvcsId(kernel::ffi::c_int);
+
+impl OvcsId {
+    /// Create and apply an overlay changeset to the live tree.
+    pub fn of_overlay_fdt_apply(overlay: &[u8], base: &DeviceNode) -> Result<Self> {
+        let mut ovcs_id: kernel::ffi::c_int = 0;
+
+        crate::error::to_result(unsafe {
+            bindings::of_overlay_fdt_apply(
+                overlay.as_ptr().cast(),
+                overlay.len().try_into().unwrap(),
+                &mut ovcs_id,
+                base.as_raw(),
+            )
+        })?;
+
+        Ok(Self(ovcs_id))
+    }
+}
+
+impl Drop for OvcsId {
+    fn drop(&mut self) {
+        unsafe { bindings::of_overlay_remove(&mut self.0) };
+    }
+}

-- 
2.49.0