Same thing as OpaquePlane, but for encoders now.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
V3:
* Add safety comment to ModeObject implementation
* Add safety comments for AsRawEncoder
* Implement try_from_opaque() and from_opaque() using a macro
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
rust/kernel/drm/kms/encoder.rs | 91 +++++++++++++++++++++++++++++++++-
1 file changed, 90 insertions(+), 1 deletion(-)
diff --git a/rust/kernel/drm/kms/encoder.rs b/rust/kernel/drm/kms/encoder.rs
index 2e4e88055c890..9ae2ff8eb5d50 100644
--- a/rust/kernel/drm/kms/encoder.rs
+++ b/rust/kernel/drm/kms/encoder.rs
@@ -4,7 +4,7 @@
//!
//! C header: [`include/drm/drm_encoder.h`](srctree/include/drm/drm_encoder.h)
-use super::{KmsDriver, ModeObject, StaticModeObject, UnregisteredKmsDevice};
+use super::{KmsDriver, ModeObject, ModeObjectVtable, StaticModeObject, UnregisteredKmsDevice};
use crate::{
alloc::KBox,
drm::device::Device,
@@ -219,6 +219,25 @@ unsafe fn from_raw<'a>(ptr: *mut bindings::drm_encoder) -> &'a Self {
}
}
+// SAFETY: `funcs` is initialized when the encoder is allocated
+unsafe impl<T: DriverEncoder> ModeObjectVtable for Encoder<T> {
+ type Vtable = bindings::drm_encoder_funcs;
+
+ fn vtable(&self) -> *const Self::Vtable {
+ // SAFETY: `as_raw()` always returns a valid pointer to an encoder
+ unsafe { *self.as_raw() }.funcs
+ }
+}
+
+impl<T: DriverEncoder> Encoder<T> {
+ super::impl_from_opaque_mode_obj! {
+ fn <'a, D>(&'a OpaqueEncoder<D>) -> &'a Self;
+ use
+ T as DriverEncoder,
+ D as KmsDriver
+ }
+}
+
/// A [`Encoder`] that has not yet been registered with userspace.
///
/// KMS registration is single-threaded, so this object is not thread-safe.
@@ -311,6 +330,76 @@ pub fn new<'a, 'b: 'a>(
}
}
+/// A [`struct drm_encoder`] without a known [`DriverEncoder`] implementation.
+///
+/// This is mainly for situations where our bindings can't infer the [`DriverEncoder`] implementation
+/// for a [`struct drm_encoder`] automatically. It is identical to [`Encoder`], except that it does not
+/// provide access to the driver's private data.
+///
+/// # Invariants
+///
+/// Same as [`Encoder`].
+#[repr(transparent)]
+pub struct OpaqueEncoder<T: KmsDriver> {
+ encoder: Opaque<bindings::drm_encoder>,
+ _p: PhantomData<T>,
+}
+
+impl<T: KmsDriver> Sealed for OpaqueEncoder<T> {}
+
+// SAFETY: All of our encoder interfaces are thread-safe
+unsafe impl<T: KmsDriver> Send for OpaqueEncoder<T> {}
+
+// SAFETY: All of our encoder interfaces are thread-safe
+unsafe impl<T: KmsDriver> Sync for OpaqueEncoder<T> {}
+
+// SAFETY: We don't expose OpaqueEncoder<T> to users before `base` is initialized in
+// OpaqueEncoder::new(), so `raw_mode_obj` always returns a valid poiner to a
+// bindings::drm_mode_object.
+unsafe impl<T: KmsDriver> ModeObject for OpaqueEncoder<T> {
+ type Driver = T;
+
+ fn drm_dev(&self) -> &Device<Self::Driver> {
+ // SAFETY: DRM encoders exist for as long as the device does, so this pointer is always
+ // valid
+ unsafe { Device::borrow((*self.encoder.get()).dev) }
+ }
+
+ fn raw_mode_obj(&self) -> *mut bindings::drm_mode_object {
+ // SAFETY: We don't expose Encoder<T> to users before it's initialized, so `base` is always
+ // initialized
+ unsafe { addr_of_mut!((*self.encoder.get()).base) }
+ }
+}
+
+// SAFETY: Encoders do not have a refcount
+unsafe impl<T: KmsDriver> StaticModeObject for OpaqueEncoder<T> {}
+
+// SAFETY:
+// - Via our type variants our data layout is identical to with `drm_encoder`
+// - Since we don't expose `Encoder` to users before it has been initialized, this and our data
+// layout ensure that `as_raw()` always returns a valid pointer to a `drm_encoder`.
+unsafe impl<T: KmsDriver> AsRawEncoder for OpaqueEncoder<T> {
+ fn as_raw(&self) -> *mut bindings::drm_encoder {
+ self.encoder.get()
+ }
+
+ unsafe fn from_raw<'a>(ptr: *mut bindings::drm_encoder) -> &'a Self {
+ // SAFETY: Our data layout is identical to `bindings::drm_encoder`
+ unsafe { &*ptr.cast() }
+ }
+}
+
+// SAFETY: `funcs` is initialized when the encoder is allocated
+unsafe impl<T: KmsDriver> ModeObjectVtable for OpaqueEncoder<T> {
+ type Vtable = bindings::drm_encoder_funcs;
+
+ fn vtable(&self) -> *const Self::Vtable {
+ // SAFETY: `as_raw()` always returns a valid pointer to an encoder
+ unsafe { *self.as_raw() }.funcs
+ }
+}
+
unsafe extern "C" fn encoder_destroy_callback<T: DriverEncoder>(
encoder: *mut bindings::drm_encoder,
) {
--
2.48.1
