rust: driver: add DriverData type to the DriverLayout trait

Add an associated type DriverData to the DriverLayout trait indicating
the type of the driver's device private data.

Acked-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Igor Korotin <igor.korotin.linux@gmail.com>
Link: https://patch.msgid.link/20260107103511.570525-6-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: Danilo Krummrich

rust/kernel/auxiliary.rs

@@ -25,10 +25,12 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::auxiliary_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
 // - `struct auxiliary_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::auxiliary_driver;
+    type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 

rust/kernel/driver.rs

@@ -108,11 +108,15 @@ use pin_init::{pin_data, pinned_drop, PinInit};
 ///
 /// Implementors must guarantee that:
 /// - `DriverType` is `repr(C)`,
+/// - `DriverData` is the type of the driver's device private data.
 /// - `DriverType` embeds a valid `struct device_driver` at byte offset `DEVICE_DRIVER_OFFSET`.
 pub unsafe trait DriverLayout {
     /// The specific driver type embedding a `struct device_driver`.
     type DriverType: Default;
 
+    /// The type of the driver's device private data.
+    type DriverData;
+
     /// Byte offset of the embedded `struct device_driver` within `DriverType`.
     ///
     /// This must correspond exactly to the location of the embedded `struct device_driver` field.

rust/kernel/i2c.rs

@@ -94,10 +94,12 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::i2c_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
 // - `struct i2c_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::i2c_driver;
+    type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 

rust/kernel/pci.rs

@@ -52,10 +52,12 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::pci_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
 // - `struct pci_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::pci_driver;
+    type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 

rust/kernel/platform.rs

@@ -28,10 +28,12 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::platform_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
 // - `struct platform_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::platform_driver;
+    type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 

rust/kernel/usb.rs

@@ -29,10 +29,12 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::usb_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
 // - `struct usb_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
 unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::usb_driver;
+    type DriverData = T;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }