[PATCH v2 1/8] rust: device: support `dev_printk` on all devices

[Gary Guo <gary@kernel.org>]

From: Gary Guo <gary@garyguo.net>

Currently, `dev_*` only works on the core `Device`, but not on any other
bus or class device objects. This causes a pattern of
`dev_info!(pdev.as_ref())` which is not ideal.

This adds support of using these devices directly with `dev_*` macros, by
adding `AsRef` call inside the macro. To make sure we can still use just
`kernel::device::Device`, as `AsRef` implementation is added for it; this
is typical for types that is designed to use with `AsRef` anyway, for
example, `str` implements `AsRef<str>` and `Path` implements `AsRef<Path>`.

Signed-off-by: Gary Guo <gary@garyguo.net>
---

Notes:
    v1 -> v2:
    - split change to samples/rust to subsystems
    - converted more cases where `as_ref()` is only for dev_printk
    - Link to v1: https://lore.kernel.org/rust-for-linux/20260120181152.3640314-1-gary@kernel.org/

 rust/kernel/device.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index c7b5db9dcca1..94e0548e7687 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -601,6 +601,13 @@ impl DeviceContext for Core {}
 impl DeviceContext for CoreInternal {}
 impl DeviceContext for Normal {}
 
+impl<Ctx: DeviceContext> AsRef<Device<Ctx>> for Device<Ctx> {
+    #[inline]
+    fn as_ref(&self) -> &Device<Ctx> {
+        self
+    }
+}
+
 /// Convert device references to bus device references.
 ///
 /// Bus devices can implement this trait to allow abstractions to provide the bus device in
@@ -720,7 +727,7 @@ macro_rules! impl_device_context_into_aref {
 macro_rules! dev_printk {
     ($method:ident, $dev:expr, $($f:tt)*) => {
         {
-            ($dev).$method($crate::prelude::fmt!($($f)*));
+            $crate::device::Device::$method($dev.as_ref(), $crate::prelude::fmt!($($f)*))
         }
     }
 }

base-commit: a0c666c25aeefd16f4b088c6549a6fb6b65a8a1d
-- 
2.51.2