rust: auxiliary: use generic device drvdata accessors

Take advantage of the generic drvdata accessors of the generic Device
type.

While at it, use from_result() instead of match.

Link: https://lore.kernel.org/r/20250621195118.124245-6-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/helpers/auxiliary.c

@@ -2,16 +2,6 @@
 
 #include <linux/auxiliary_bus.h>
 
-void rust_helper_auxiliary_set_drvdata(struct auxiliary_device *adev, void *data)
-{
-	auxiliary_set_drvdata(adev, data);
-}
-
-void *rust_helper_auxiliary_get_drvdata(struct auxiliary_device *adev)
-{
-	return auxiliary_get_drvdata(adev);
-}
-
 void rust_helper_auxiliary_device_uninit(struct auxiliary_device *adev)
 {
 	return auxiliary_device_uninit(adev);

rust/kernel/auxiliary.rs

@@ -8,9 +8,9 @@ use crate::{
     bindings, container_of, device,
     device_id::RawDeviceId,
     driver,
-    error::{to_result, Result},
+    error::{from_result, to_result, Result},
     prelude::*,
-    types::{ForeignOwnable, Opaque},
+    types::Opaque,
     ThisModule,
 };
 use core::{
@@ -60,37 +60,32 @@ impl<T: Driver + 'static> Adapter<T> {
         // `struct auxiliary_device`.
         //
         // INVARIANT: `adev` is valid for the duration of `probe_callback()`.
-        let adev = unsafe { &*adev.cast::<Device<device::Core>>() };
+        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal>>() };
 
         // SAFETY: `DeviceId` is a `#[repr(transparent)`] wrapper of `struct auxiliary_device_id`
         // and does not add additional invariants, so it's safe to transmute.
         let id = unsafe { &*id.cast::<DeviceId>() };
         let info = T::ID_TABLE.info(id.index());
 
-        match T::probe(adev, info) {
+        from_result(|| {
-            Ok(data) => {
+            let data = T::probe(adev, info)?;
-                // Let the `struct auxiliary_device` own a reference of the driver's private data.
-                // SAFETY: By the type invariant `adev.as_raw` returns a valid pointer to a
-                // `struct auxiliary_device`.
-                unsafe {
-                    bindings::auxiliary_set_drvdata(adev.as_raw(), data.into_foreign().cast())
-                };
-            }
-            Err(err) => return Error::to_errno(err),
-        }
 
-        0
+            adev.as_ref().set_drvdata(data);
+            Ok(0)
+        })
     }
 
     extern "C" fn remove_callback(adev: *mut bindings::auxiliary_device) {
-        // SAFETY: The auxiliary bus only ever calls the remove callback with a valid pointer to a
+        // SAFETY: The auxiliary bus only ever calls the probe callback with a valid pointer to a
         // `struct auxiliary_device`.
-        let ptr = unsafe { bindings::auxiliary_get_drvdata(adev) };
+        //
+        // INVARIANT: `adev` is valid for the duration of `probe_callback()`.
+        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal>>() };
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
-        // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
+        // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // `KBox<T>` pointer created through `KBox::into_foreign`.
+        // and stored a `Pin<KBox<T>>`.
-        drop(unsafe { KBox::<T>::from_foreign(ptr.cast()) });
+        drop(unsafe { adev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() });
     }
 }