rust: net::phy represent DeviceId as transparent wrapper over mdio_device_id

Refactor the DeviceId struct to be a #[repr(transparent)] wrapper
around the C struct bindings::mdio_device_id.

This refactoring is a preparation for enabling the PHY abstractions to
use the RawDeviceId trait.

Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://lore.kernel.org/r/20250711040947.1252162-3-fujita.tomonori@gmail.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: fujita

rust/kernel/net/phy.rs

@@ -507,7 +507,7 @@ pub const fn create_phy_driver<T: Driver>() -> DriverVTable {
     DriverVTable(Opaque::new(bindings::phy_driver {
         name: T::NAME.as_char_ptr().cast_mut(),
         flags: T::FLAGS,
-        phy_id: T::PHY_DEVICE_ID.id,
+        phy_id: T::PHY_DEVICE_ID.id(),
         phy_id_mask: T::PHY_DEVICE_ID.mask_as_int(),
         soft_reset: if T::HAS_SOFT_RESET {
             Some(Adapter::<T>::soft_reset_callback)
@@ -691,61 +691,62 @@ impl Drop for Registration {
 ///
 /// Represents the kernel's `struct mdio_device_id`. This is used to find an appropriate
 /// PHY driver.
-pub struct DeviceId {
-    id: u32,
-    mask: DeviceMask,
-}
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct DeviceId(bindings::mdio_device_id);
 
 impl DeviceId {
     /// Creates a new instance with the exact match mask.
     pub const fn new_with_exact_mask(id: u32) -> Self {
-        DeviceId {
-            id,
-            mask: DeviceMask::Exact,
-        }
+        Self(bindings::mdio_device_id {
+            phy_id: id,
+            phy_id_mask: DeviceMask::Exact.as_int(),
+        })
     }
 
     /// Creates a new instance with the model match mask.
     pub const fn new_with_model_mask(id: u32) -> Self {
-        DeviceId {
-            id,
-            mask: DeviceMask::Model,
-        }
+        Self(bindings::mdio_device_id {
+            phy_id: id,
+            phy_id_mask: DeviceMask::Model.as_int(),
+        })
     }
 
     /// Creates a new instance with the vendor match mask.
     pub const fn new_with_vendor_mask(id: u32) -> Self {
-        DeviceId {
-            id,
-            mask: DeviceMask::Vendor,
-        }
+        Self(bindings::mdio_device_id {
+            phy_id: id,
+            phy_id_mask: DeviceMask::Vendor.as_int(),
+        })
     }
 
     /// Creates a new instance with a custom match mask.
     pub const fn new_with_custom_mask(id: u32, mask: u32) -> Self {
-        DeviceId {
-            id,
-            mask: DeviceMask::Custom(mask),
-        }
+        Self(bindings::mdio_device_id {
+            phy_id: id,
+            phy_id_mask: DeviceMask::Custom(mask).as_int(),
+        })
     }
 
     /// Creates a new instance from [`Driver`].
     pub const fn new_with_driver<T: Driver>() -> Self {
         T::PHY_DEVICE_ID
     }
 
-    /// Get a `mask` as u32.
+    /// Get the MDIO device's PHY ID.
+    pub const fn id(&self) -> u32 {
+        self.0.phy_id
+    }
+
+    /// Get the MDIO device's match mask.
     pub const fn mask_as_int(&self) -> u32 {
-        self.mask.as_int()
+        self.0.phy_id_mask
     }
 
     // macro use only
     #[doc(hidden)]
     pub const fn mdio_device_id(&self) -> bindings::mdio_device_id {
-        bindings::mdio_device_id {
-            phy_id: self.id,
-            phy_id_mask: self.mask.as_int(),
-        }
+        self.0
     }
 }