1 files changed, 51 insertions, 21 deletions

diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
index 01b5bd47a333..c8b66d816871 100644
--- a/rust/kernel/drm/gem/mod.rs
+++ b/rust/kernel/drm/gem/mod.rs
@@ -8,6 +8,10 @@ use crate::{
     bindings,
     drm::{
         self,
+        device::{
+            DeviceContext,
+            Registered, //
+        },
         driver::{
             AllocImpl,
             AllocOps, //
@@ -22,6 +26,7 @@ use crate::{
     types::Opaque,
 };
 use core::{
+    marker::PhantomData,
     ops::Deref,
     ptr::NonNull, //
 };
@@ -73,6 +78,12 @@ pub(crate) use impl_aref_for_gem_obj;
 /// [`DriverFile`]: drm::file::DriverFile
 pub type DriverFile<T> = drm::File<<<T as DriverObject>::Driver as drm::Driver>::File>;
 
+/// A type alias for retrieving the current [`AllocImpl`] for a given [`DriverObject`].
+///
+/// [`Driver`]: drm::Driver
+pub type DriverAllocImpl<T, Ctx = Registered> =
+    <<T as DriverObject>::Driver as drm::Driver>::Object<Ctx>;
+
 /// GEM object functions, which must be implemented by drivers.
 pub trait DriverObject: Sync + Send + Sized {
     /// Parent `Driver` for this object.
@@ -82,19 +93,19 @@ pub trait DriverObject: Sync + Send + Sized {
     type Args;
 
     /// Create a new driver data object for a GEM object of a given size.
-    fn new(
-        dev: &drm::Device<Self::Driver>,
+    fn new<Ctx: DeviceContext>(
+        dev: &drm::Device<Self::Driver, Ctx>,
         size: usize,
         args: Self::Args,
     ) -> impl PinInit<Self, Error>;
 
     /// Open a new handle to an existing object, associated with a File.
-    fn open(_obj: &<Self::Driver as drm::Driver>::Object, _file: &DriverFile<Self>) -> Result {
+    fn open(_obj: &DriverAllocImpl<Self>, _file: &DriverFile<Self>) -> Result {
         Ok(())
     }
 
     /// Close a handle to an existing object, associated with a File.
-    fn close(_obj: &<Self::Driver as drm::Driver>::Object, _file: &DriverFile<Self>) {}
+    fn close(_obj: &DriverAllocImpl<Self>, _file: &DriverFile<Self>) {}
 }
 
 /// Trait that represents a GEM object subtype
@@ -120,9 +131,12 @@ extern "C" fn open_callback<T: DriverObject>(
     // SAFETY: `open_callback` is only ever called with a valid pointer to a `struct drm_file`.
     let file = unsafe { DriverFile::<T>::from_raw(raw_file) };
 
-    // SAFETY: `open_callback` is specified in the AllocOps structure for `DriverObject<T>`,
-    // ensuring that `raw_obj` is contained within a `DriverObject<T>`
-    let obj = unsafe { <<T::Driver as drm::Driver>::Object as IntoGEMObject>::from_raw(raw_obj) };
+    // SAFETY:
+    // * `open_callback` is specified in the AllocOps structure for `DriverObject`, ensuring that
+    //   `raw_obj` is contained within a `DriverAllocImpl<T>`
+    // * It is only possible for `open_callback` to be called after device registration, ensuring
+    //   that the object's device is in the `Registered` state.
+    let obj: &DriverAllocImpl<T> = unsafe { IntoGEMObject::from_raw(raw_obj) };
 
     match T::open(obj, file) {
         Err(e) => e.to_errno(),
@@ -139,12 +153,12 @@ extern "C" fn close_callback<T: DriverObject>(
 
     // SAFETY: `close_callback` is specified in the AllocOps structure for `Object<T>`, ensuring
     // that `raw_obj` is indeed contained within a `Object<T>`.
-    let obj = unsafe { <<T::Driver as drm::Driver>::Object as IntoGEMObject>::from_raw(raw_obj) };
+    let obj: &DriverAllocImpl<T> = unsafe { IntoGEMObject::from_raw(raw_obj) };
 
     T::close(obj, file);
 }
 
-impl<T: DriverObject> IntoGEMObject for Object<T> {
+impl<T: DriverObject, Ctx: DeviceContext> IntoGEMObject for Object<T, Ctx> {
     fn as_raw(&self) -> *mut bindings::drm_gem_object {
         self.obj.get()
     }
@@ -152,7 +166,7 @@ impl<T: DriverObject> IntoGEMObject for Object<T> {
     unsafe fn from_raw<'a>(self_ptr: *mut bindings::drm_gem_object) -> &'a Self {
         // SAFETY: `obj` is guaranteed to be in an `Object<T>` via the safety contract of this
         // function
-        unsafe { &*crate::container_of!(Opaque::cast_from(self_ptr), Object<T>, obj) }
+        unsafe { &*crate::container_of!(Opaque::cast_from(self_ptr), Object<T, Ctx>, obj) }
     }
 }
 
@@ -169,7 +183,7 @@ pub trait BaseObject: IntoGEMObject {
     fn create_handle<D, F>(&self, file: &drm::File<F>) -> Result<u32>
     where
         Self: AllocImpl<Driver = D>,
-        D: drm::Driver<Object = Self, File = F>,
+        D: drm::Driver<Object<Registered> = Self, File = F>,
         F: drm::file::DriverFile<Driver = D>,
     {
         let mut handle: u32 = 0;
@@ -184,7 +198,7 @@ pub trait BaseObject: IntoGEMObject {
     fn lookup_handle<D, F>(file: &drm::File<F>, handle: u32) -> Result<ARef<Self>>
     where
         Self: AllocImpl<Driver = D>,
-        D: drm::Driver<Object = Self, File = F>,
+        D: drm::Driver<Object<Registered> = Self, File = F>,
         F: drm::file::DriverFile<Driver = D>,
     {
         // SAFETY: The arguments are all valid per the type invariants.
@@ -236,16 +250,18 @@ impl<T: IntoGEMObject> BaseObjectPrivate for T {}
 ///
 /// # Invariants
 ///
-/// - `self.obj` is a valid instance of a `struct drm_gem_object`.
+/// * `self.obj` is a valid instance of a `struct drm_gem_object`.
+/// * Any type invariants of `Ctx` apply to the parent DRM device for this GEM object.
 #[repr(C)]
 #[pin_data]
-pub struct Object<T: DriverObject + Send + Sync> {
+pub struct Object<T: DriverObject + Send + Sync, Ctx: DeviceContext = Registered> {
     obj: Opaque<bindings::drm_gem_object>,
     #[pin]
     data: T,
+    _ctx: PhantomData<Ctx>,
 }
 
-impl<T: DriverObject> Object<T> {
+impl<T: DriverObject, Ctx: DeviceContext> Object<T, Ctx> {
     const OBJECT_FUNCS: bindings::drm_gem_object_funcs = bindings::drm_gem_object_funcs {
         free: Some(Self::free_callback),
         open: Some(open_callback::<T>),
@@ -265,11 +281,16 @@ impl<T: DriverObject> Object<T> {
     };
 
     /// Create a new GEM object.
-    pub fn new(dev: &drm::Device<T::Driver>, size: usize, args: T::Args) -> Result<ARef<Self>> {
+    pub fn new(
+        dev: &drm::Device<T::Driver, Ctx>,
+        size: usize,
+        args: T::Args,
+    ) -> Result<ARef<Self>> {
         let obj: Pin<KBox<Self>> = KBox::pin_init(
             try_pin_init!(Self {
                 obj: Opaque::new(bindings::drm_gem_object::default()),
                 data <- T::new(dev, size, args),
+                _ctx: PhantomData,
             }),
             GFP_KERNEL,
         )?;
@@ -277,6 +298,8 @@ impl<T: DriverObject> Object<T> {
         // SAFETY: `obj.as_raw()` is guaranteed to be valid by the initialization above.
         unsafe { (*obj.as_raw()).funcs = &Self::OBJECT_FUNCS };
 
+        // INVARIANT: `dev` and the GEM object are in the same state at the moment, and upgrading
+        // the typestate in `dev` will not carry over to the GEM object.
         if let Err(err) =
             // SAFETY: The arguments are all valid per the type invariants.
             to_result(unsafe {
@@ -300,13 +323,15 @@ impl<T: DriverObject> Object<T> {
     }
 
     /// Returns the `Device` that owns this GEM object.
-    pub fn dev(&self) -> &drm::Device<T::Driver> {
+    pub fn dev(&self) -> &drm::Device<T::Driver, Ctx> {
         // SAFETY:
         // - `struct drm_gem_object.dev` is initialized and valid for as long as the GEM
         //   object lives.
         // - The device we used for creating the gem object is passed as &drm::Device<T::Driver> to
         //   Object::<T>::new(), so we know that `T::Driver` is the right generic parameter to use
         //   here.
+        // - Any type invariants of `Ctx` are upheld by using the same `Ctx` for the `Device` we
+        //   return.
         unsafe { drm::Device::from_raw((*self.as_raw()).dev) }
     }
 
@@ -331,11 +356,16 @@ impl<T: DriverObject> Object<T> {
     }
 }
 
-impl_aref_for_gem_obj!(impl<T> for Object<T> where T: DriverObject);
+impl_aref_for_gem_obj! {
+    impl<T, C> for Object<T, C>
+    where
+        T: DriverObject,
+        C: DeviceContext
+}
 
-impl<T: DriverObject> super::private::Sealed for Object<T> {}
+impl<T: DriverObject, Ctx: DeviceContext> super::private::Sealed for Object<T, Ctx> {}
 
-impl<T: DriverObject> Deref for Object<T> {
+impl<T: DriverObject, Ctx: DeviceContext> Deref for Object<T, Ctx> {
     type Target = T;
 
     fn deref(&self) -> &Self::Target {
@@ -343,7 +373,7 @@ impl<T: DriverObject> Deref for Object<T> {
     }
 }
 
-impl<T: DriverObject> AllocImpl for Object<T> {
+impl<T: DriverObject, Ctx: DeviceContext> AllocImpl for Object<T, Ctx> {
     type Driver = T::Driver;
 
     const ALLOC_OPS: AllocOps = AllocOps {