[PATCH net-next v3 3/6] rust: net::phy implement AsRef<kernel::device::Device> trait

[FUJITA Tomonori <fujita.tomonori@gmail.com>]

Implement AsRef<kernel::device::Device> trait for Device. A PHY driver
needs a reference to device::Device to call the firmware API.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/net/phy.rs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 60d3d8f8b44f..bd9fc7a84cd4 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -7,8 +7,7 @@
 //! C headers: [`include/linux/phy.h`](srctree/include/linux/phy.h).
 
 use crate::{error::*, prelude::*, types::Opaque};
-
-use core::marker::PhantomData;
+use core::{marker::PhantomData, ptr::addr_of_mut};
 
 /// PHY state machine states.
 ///
@@ -302,6 +301,15 @@ pub fn genphy_read_abilities(&mut self) -> Result {
     }
 }
 
+impl AsRef<kernel::device::Device> for Device {
+    fn as_ref(&self) -> &kernel::device::Device {
+        let phydev = self.0.get();
+        // SAFETY: The struct invariant ensures that we may access
+        // this field without additional synchronization.
+        unsafe { kernel::device::Device::as_ref(addr_of_mut!((*phydev).mdio.dev)) }
+    }
+}
+
 /// Defines certain other features this PHY supports (like interrupts).
 ///
 /// These flag values are used in [`Driver::FLAGS`].
-- 
2.34.1