[PATCH 1/8] rust: device: introduce device::Internal

[Danilo Krummrich <dakr@kernel.org>]

Introduce an internal device context, which is semantically equivalent
to the Core device context, but reserved for bus abstractions.

This allows implementing methods for the Device type, which are limited
to be used within the core context of bus abstractions, i.e. restrict
the availability for drivers.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/device.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 665f5ceadecc..e9094d8322d5 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -261,6 +261,10 @@ pub trait DeviceContext: private::Sealed {}
 /// any of the bus callbacks, such as `probe()`.
 pub struct Core;
 
+/// Semantically the same as [`Core`] but reserved for internal usage of the corresponding bus
+/// abstraction.
+pub struct Internal;
+
 /// The [`Bound`] context is the context of a bus specific device reference when it is guaranteed to
 /// be bound for the duration of its lifetime.
 pub struct Bound;
@@ -270,11 +274,13 @@ pub trait Sealed {}
 
     impl Sealed for super::Bound {}
     impl Sealed for super::Core {}
+    impl Sealed for super::Internal {}
     impl Sealed for super::Normal {}
 }
 
 impl DeviceContext for Bound {}
 impl DeviceContext for Core {}
+impl DeviceContext for Internal {}
 impl DeviceContext for Normal {}
 
 /// # Safety
@@ -312,6 +318,13 @@ fn deref(&self) -> &Self::Target {
 #[macro_export]
 macro_rules! impl_device_context_deref {
     (unsafe { $device:ident }) => {
+        // SAFETY: This macro has the exact same safety requirement as
+        // `__impl_device_context_deref!`.
+        ::kernel::__impl_device_context_deref!(unsafe {
+            $device,
+            $crate::device::Internal => $crate::device::Core
+        });
+
         // SAFETY: This macro has the exact same safety requirement as
         // `__impl_device_context_deref!`.
         ::kernel::__impl_device_context_deref!(unsafe {
@@ -345,6 +358,7 @@ fn from(dev: &$device<$src>) -> Self {
 #[macro_export]
 macro_rules! impl_device_context_into_aref {
     ($device:tt) => {
+        ::kernel::__impl_device_context_into_aref!($crate::device::Internal, $device);
         ::kernel::__impl_device_context_into_aref!($crate::device::Core, $device);
         ::kernel::__impl_device_context_into_aref!($crate::device::Bound, $device);
     };
-- 
2.49.0