[PATCH v2 2/9] rust: device: implement impl_device_context_into_aref!

[Danilo Krummrich <dakr@kernel.org>]

Implement a macro to implement all From conversions of a certain device
to ARef<Device>.

This avoids unnecessary boiler plate code for every device
implementation.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/device.rs   | 21 +++++++++++++++++++++
 rust/kernel/pci.rs      |  7 +------
 rust/kernel/platform.rs |  9 ++-------
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 7cb6f0fc005d..26e71224460b 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -279,6 +279,27 @@ macro_rules! impl_device_context_deref {
     };
 }
 
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __impl_device_context_into_aref {
+    ($src:ty, $device:tt) => {
+        impl core::convert::From<&$device<$src>> for $crate::types::ARef<$device> {
+            fn from(dev: &$device<$src>) -> Self {
+                (&**dev).into()
+            }
+        }
+    };
+}
+
+/// Implement [`core::convert::From`], such that all `&Device<Ctx>` can be converted to an
+/// `ARef<Device>`.
+#[macro_export]
+macro_rules! impl_device_context_into_aref {
+    ($device:tt) => {
+        kernel::__impl_device_context_into_aref!($crate::device::Core, $device);
+    };
+}
+
 #[doc(hidden)]
 #[macro_export]
 macro_rules! dev_printk {
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 8474608e7a90..7c6ec05383e0 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -425,12 +425,7 @@ pub fn set_master(&self) {
 // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
 // argument.
 kernel::impl_device_context_deref!(unsafe { Device });
-
-impl From<&Device<device::Core>> for ARef<Device> {
-    fn from(dev: &Device<device::Core>) -> Self {
-        (&**dev).into()
-    }
-}
+kernel::impl_device_context_into_aref!(Device);
 
 // SAFETY: Instances of `Device` are always reference-counted.
 unsafe impl crate::types::AlwaysRefCounted for Device {
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 22590bdff7bb..9476b717c425 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -10,7 +10,7 @@
     of,
     prelude::*,
     str::CStr,
-    types::{ARef, ForeignOwnable, Opaque},
+    types::{ForeignOwnable, Opaque},
     ThisModule,
 };
 
@@ -192,12 +192,7 @@ fn as_raw(&self) -> *mut bindings::platform_device {
 // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
 // argument.
 kernel::impl_device_context_deref!(unsafe { Device });
-
-impl From<&Device<device::Core>> for ARef<Device> {
-    fn from(dev: &Device<device::Core>) -> Self {
-        (&**dev).into()
-    }
-}
+kernel::impl_device_context_into_aref!(Device);
 
 // SAFETY: Instances of `Device` are always reference-counted.
 unsafe impl crate::types::AlwaysRefCounted for Device {
-- 
2.49.0