[v2,3/9] rust: device: implement device context for Device

Commit Message

Danilo Krummrich April 13, 2025, 5:36 p.m. UTC

Analogous to bus specific device, implement the DeviceContext generic
for generic devices.

This is used for APIs that work with generic devices (such as Devres) to
evaluate the device' context.

Signed-off-by: Danilo Krummrich <[e-mail]>
---
 rust/kernel/device.rs | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Comments

Benno Lossin April 14, 2025, 10:31 a.m. UTC | #1

On Sun Apr 13, 2025 at 7:36 PM CEST, Danilo Krummrich wrote:
> Analogous to bus specific device, implement the DeviceContext generic
> for generic devices.
>
> This is used for APIs that work with generic devices (such as Devres) to
> evaluate the device' context.
>
> Signed-off-by: Danilo Krummrich <[e-mail]>

Reviewed-by: Benno Lossin <[e-mail]>

---
Cheers,
Benno

> ---
>  rust/kernel/device.rs | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

Bjorn Helgaas April 15, 2025, 8:47 p.m. UTC | #2

On Sun, Apr 13, 2025 at 07:36:58PM +0200, Danilo Krummrich wrote:
> Analogous to bus specific device, implement the DeviceContext generic
> for generic devices.
> 
> This is used for APIs that work with generic devices (such as Devres) to
> evaluate the device' context.

Looks like a stray ', but maybe it's some rust thing I don't know
about.

Patch

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 26e71224460b..487211842f77 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -9,7 +9,7 @@ 
     str::CStr,
     types::{ARef, Opaque},
 };
-use core::{fmt, ptr};
+use core::{fmt, marker::PhantomData, ptr};
 
 #[cfg(CONFIG_PRINTK)]
 use crate::c_str;
@@ -42,7 +42,7 @@ 
 /// `bindings::device::release` is valid to be called from any thread, hence `ARef<Device>` can be
 /// dropped from any thread.
 #[repr(transparent)]
-pub struct Device(Opaque<bindings::device>);
+pub struct Device<Ctx: DeviceContext = Normal>(Opaque<bindings::device>, PhantomData<Ctx>);
 
 impl Device {
     /// Creates a new reference-counted abstraction instance of an existing `struct device` pointer.
@@ -59,7 +59,9 @@  pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> {
         // SAFETY: By the safety requirements ptr is valid
         unsafe { Self::as_ref(ptr) }.into()
     }
+}
 
+impl<Ctx: DeviceContext> Device<Ctx> {
     /// Obtain the raw `struct device *`.
     pub(crate) fn as_raw(&self) -> *mut bindings::device {
         self.0.get()
@@ -189,6 +191,11 @@  pub fn property_present(&self, name: &CStr) -> bool {
     }
 }
 
+// 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 });
+kernel::impl_device_context_into_aref!(Device);
+
 // SAFETY: Instances of `Device` are always reference-counted.
 unsafe impl crate::types::AlwaysRefCounted for Device {
     fn inc_ref(&self) {