[PATCH 1/6] rust: drm: Add Driver::ParentDevice associated type

[Danilo Krummrich <dakr@kernel.org>]

Add a ParentDevice associated type to the Driver trait, allowing each
DRM driver to declare its parent bus device type (e.g.
auxiliary::Device, platform::Device).

Change UnregisteredDevice::new() to take &T::ParentDevice<Bound>,
ensuring at the type level that the DRM device's parent matches the
declared bus device type.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/drm/nova/driver.rs | 8 ++++++--
 drivers/gpu/drm/tyr/driver.rs  | 6 ++++--
 rust/kernel/drm/device.rs      | 7 +++++--
 rust/kernel/drm/driver.rs      | 3 +++
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index 9eef28b506bb..9d4100f01ea7 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -2,7 +2,10 @@
 
 use kernel::{
     auxiliary,
-    device::Core,
+    device::{
+        Core,
+        DeviceContext, //
+    },
     drm::{
         self,
         gem,
@@ -59,7 +62,7 @@ fn probe(
     ) -> impl PinInit<Self, Error> + 'bound {
         let data = try_pin_init!(NovaData { adev: adev.into() });
 
-        let drm = drm::UnregisteredDevice::<Self>::new(adev.as_ref(), data)?;
+        let drm = drm::UnregisteredDevice::<Self>::new(adev, data)?;
         let drm = drm::Registration::new_foreign_owned(drm, adev.as_ref(), 0)?;
 
         Ok(Self { drm: drm.into() })
@@ -71,6 +74,7 @@ impl drm::Driver for NovaDriver {
     type Data = NovaData;
     type File = File;
     type Object<Ctx: drm::DeviceContext> = gem::Object<NovaObject, Ctx>;
+    type ParentDevice<Ctx: DeviceContext> = auxiliary::Device<Ctx>;
 
     const INFO: drm::DriverInfo = INFO;
 
diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index 2743178af325..747745d23f31 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -8,7 +8,8 @@
     device::{
         Bound,
         Core,
-        Device, //
+        Device,
+        DeviceContext, //
     },
     drm,
     drm::ioctl,
@@ -131,7 +132,7 @@ fn probe(
                 gpu_info,
         });
 
-        let tdev = drm::UnregisteredDevice::<TyrDrmDriver>::new(pdev.as_ref(), data)?;
+        let tdev = drm::UnregisteredDevice::<TyrDrmDriver>::new(pdev, data)?;
         let tdev = drm::driver::Registration::new_foreign_owned(tdev, pdev.as_ref(), 0)?;
 
         let driver = TyrPlatformDriverData {
@@ -176,6 +177,7 @@ impl drm::Driver for TyrDrmDriver {
     type Data = TyrDrmDeviceData;
     type File = TyrDrmFileData;
     type Object<R: drm::DeviceContext> = drm::gem::Object<TyrObject, R>;
+    type ParentDevice<Ctx: DeviceContext> = platform::Device<Ctx>;
 
     const INFO: drm::DriverInfo = INFO;
 
diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index d91f19dcc375..492c2f2c7ca4 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -197,7 +197,10 @@ impl<T: drm::Driver> UnregisteredDevice<T> {
     /// Create a new `UnregisteredDevice` for a `drm::Driver`.
     ///
     /// This can be used to create a [`Registration`](kernel::drm::Registration).
-    pub fn new(dev: &device::Device, data: impl PinInit<T::Data, Error>) -> Result<Self> {
+    pub fn new(
+        dev: &T::ParentDevice<device::Bound>,
+        data: impl PinInit<T::Data, Error>,
+    ) -> Result<Self> {
         // `__drm_dev_alloc` uses `kmalloc()` to allocate memory, hence ensure a `kmalloc()`
         // compatible `Layout`.
         let layout = Kmalloc::aligned_layout(Layout::new::<Device<T, Uninit>>());
@@ -207,7 +210,7 @@ pub fn new(dev: &device::Device, data: impl PinInit<T::Data, Error>) -> Result<S
         // - `dev` is valid by its type invarants,
         let raw_drm: *mut Device<T, Uninit> = unsafe {
             bindings::__drm_dev_alloc(
-                dev.as_raw(),
+                dev.as_ref().as_raw(),
                 &Self::VTABLE,
                 layout.size(),
                 mem::offset_of!(Device<T, Uninit>, dev),
diff --git a/rust/kernel/drm/driver.rs b/rust/kernel/drm/driver.rs
index 294e17af86a3..9d06f8c5b2da 100644
--- a/rust/kernel/drm/driver.rs
+++ b/rust/kernel/drm/driver.rs
@@ -114,6 +114,9 @@ pub trait Driver {
     /// The type used to represent a DRM File (client)
     type File: drm::file::DriverFile;
 
+    /// The bus device type of the parent device that the DRM device is associated with.
+    type ParentDevice<Ctx: device::DeviceContext>: device::AsBusDevice<Ctx>;
+
     /// Driver metadata
     const INFO: DriverInfo;
 
-- 
2.54.0