The next step is adding a set of basic bindings to create a plane, which
has to happen before we can create a CRTC (since we need to be able to at
least specify a primary plane for a CRTC upon creation). This mostly
follows the same general pattern as connectors (AsRawPlane,
AsRawPlaneState, etc.).
There is one major difference with planes vs. other types of atomic mode
objects: drm_plane_state isn't the only base plane struct used in DRM
drivers, as some drivers will use helpers like drm_shadow_plane_state which
have a drm_plane_state embedded within them.
Since we'll eventually be adding bindings for shadow planes, we introduce a
PlaneStateHelper trait - which represents any data type which can be used
as the main wrapping structure around a drm_plane_state - and we implement
this trait for PlaneState<T>. This trait can be used in our C callbacks to
allow for drivers to use different wrapping structures without needing to
implement a separate set of FFI callbacks for each type. Currently planes
are the only type I'm aware of which do this.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
V2:
* Start using Gerry Guo's updated #[vtable] function so that our driver
operations table has a static location in memory
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
rust/kernel/drm/kms.rs | 1 +
rust/kernel/drm/kms/plane.rs | 504 +++++++++++++++++++++++++++++++++++
2 files changed, 505 insertions(+)
create mode 100644 rust/kernel/drm/kms/plane.rs
diff --git a/rust/kernel/drm/kms.rs b/rust/kernel/drm/kms.rs
index 0138e6830b48c..5b075794a1155 100644
--- a/rust/kernel/drm/kms.rs
+++ b/rust/kernel/drm/kms.rs
@@ -4,6 +4,7 @@
pub mod connector;
pub mod fbdev;
+pub mod plane;
use crate::{
drm::{
diff --git a/rust/kernel/drm/kms/plane.rs b/rust/kernel/drm/kms/plane.rs
new file mode 100644
index 0000000000000..3040c4546b121
--- /dev/null
+++ b/rust/kernel/drm/kms/plane.rs
@@ -0,0 +1,504 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+//! Bindings for [`struct drm_plane`] and friends.
+//!
+//! [`struct drm_plane`]: srctree/include/drm/drm_plane.h
+
+use alloc::boxed::Box;
+use crate::{
+ bindings,
+ drm::{device::Device, drv::Driver, fourcc::*},
+ error::{to_result, from_result, Error},
+ init::Zeroable,
+ prelude::*,
+ types::{ARef, Opaque},
+ private::Sealed,
+};
+use core::{
+ cell::Cell,
+ pin::Pin,
+ slice,
+ mem::{self, size_of, ManuallyDrop},
+ ptr::{self, null, null_mut, NonNull},
+ marker::*,
+ ops::*,
+};
+use macros::pin_data;
+use super::{
+ KmsDriver,
+ UnregisteredKmsDevice,
+ ModeObject,
+ StaticModeObject,
+};
+
+/// The main trait for implementing the [`struct drm_plane`] API for [`Plane`]
+///
+/// Any KMS driver should have at least one implementation of this type, which allows them to create
+/// [`Plane`] objects. Additionally, a driver may store driver-private data within the type that
+/// implements [`DriverPlane`] - and it will be made available when using a fully typed [`Plane`]
+/// object.
+///
+/// # Invariants
+///
+/// - Any C FFI callbacks generated using this trait are guaranteed that passed-in
+/// [`struct drm_plane`] pointers are contained within a [`Plane<Self>`].
+/// - Any C FFI callbacks generated using this trait are guaranteed that passed-in
+/// [`struct drm_plane_state`] pointers are contained within a [`PlaneState<Self::State>`].
+///
+/// [`struct drm_plane`]: srctree/include/drm/drm_plane.h
+/// [`struct drm_plane_state`]: srctree/include/drm/drm_plane.h
+#[vtable]
+pub trait DriverPlane: Send + Sync + Sized {
+ /// The generated C vtable for this [`DriverPlane`] implementation.
+ #[unique]
+ const OPS: &'static DriverPlaneOps = &DriverPlaneOps {
+ funcs: bindings::drm_plane_funcs {
+ update_plane: Some(bindings::drm_atomic_helper_update_plane),
+ disable_plane: Some(bindings::drm_atomic_helper_disable_plane),
+ destroy: Some(plane_destroy_callback::<Self>),
+ reset: Some(plane_reset_callback::<Self>),
+ set_property: None,
+ atomic_duplicate_state: Some(atomic_duplicate_state_callback::<Self::State>),
+ atomic_destroy_state: Some(atomic_destroy_state_callback::<Self::State>),
+ atomic_set_property: None, // TODO someday
+ atomic_get_property: None, // TODO someday
+ late_register: None, // TODO someday
+ early_unregister: None, // TODO someday
+ atomic_print_state: None, // TODO: Display someday???
+ format_mod_supported: None // TODO someday
+ },
+
+ helper_funcs: bindings::drm_plane_helper_funcs {
+ prepare_fb: None,
+ cleanup_fb: None,
+ begin_fb_access: None, // TODO: someday?
+ end_fb_access: None, // TODO: someday?
+ atomic_check: None,
+ atomic_update: None,
+ atomic_enable: None, // TODO
+ atomic_disable: None, // TODO
+ atomic_async_check: None, // TODO
+ atomic_async_update: None, // TODO
+ panic_flush: None,
+ get_scanout_buffer: None
+ }
+ };
+
+ /// The type to pass to the `args` field of [`Plane::new`].
+ ///
+ /// This type will be made available in in the `args` argument of [`Self::new`]. Drivers which
+ /// don't need this can simply pass [`()`] here.
+ type Args;
+
+ /// The parent [`Driver`] implementation.
+ type Driver: KmsDriver;
+
+ /// The [`DriverPlaneState`] implementation for this [`DriverPlane`].
+ ///
+ /// See [`DriverPlaneState`] for more info.
+ type State: DriverPlaneState;
+
+ /// The constructor for creating a [`Plane`] using this [`DriverPlane`] implementation.
+ ///
+ /// Drivers may use this to instantiate their [`DriverPlane`] object.
+ fn new(device: &Device<Self::Driver>, args: Self::Args) -> impl PinInit<Self, Error>;
+}
+
+/// The generated C vtable for a [`DriverPlane`].
+///
+/// This type is created internally by DRM.
+pub struct DriverPlaneOps {
+ funcs: bindings::drm_plane_funcs,
+ helper_funcs: bindings::drm_plane_helper_funcs,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[repr(u32)]
+/// An enumerator describing a type of [`Plane`].
+///
+/// This is mainly just relevant for DRM legacy drivers.
+pub enum PlaneType {
+ /// Overlay planes represent all non-primary, non-cursor planes. Some drivers refer to these
+ /// types of planes as "sprites" internally.
+ OVERLAY = bindings::drm_plane_type_DRM_PLANE_TYPE_OVERLAY,
+
+ /// A primary plane attached to a CRTC that is the most likely to be able to light up the CRTC
+ /// when no scaling/cropping is used, and the plane covers the whole CRTC.
+ PRIMARY = bindings::drm_plane_type_DRM_PLANE_TYPE_PRIMARY,
+
+ /// A cursor plane attached to a CRTC that is more likely to be enabled when no scaling/cropping
+ /// is used, and the framebuffer has the size indicated by [`ModeConfigInfo::max_cursor`].
+ ///
+ /// [`ModeConfigInfo::max_cursor`]: crate::drm::kms::ModeConfigInfo
+ CURSOR = bindings::drm_plane_type_DRM_PLANE_TYPE_CURSOR,
+}
+
+/// The main interface for a [`struct drm_plane`].
+///
+/// This type is the main interface for dealing with DRM planes. In addition, it also allows
+/// immutable access to whatever private data is contained within an implementor's [`DriverPlane`]
+/// type.
+///
+/// # Invariants
+///
+/// - `plane` and `inner` are initialized for as long as this object is made available to users.
+/// - The data layout of this structure begins with [`struct drm_plane`].
+/// - The atomic state for this type can always be assumed to be of type [`PlaneState<T::State>`].
+///
+/// [`struct drm_plane`]: srctree/include/drm/drm_plane.h
+#[repr(C)]
+#[pin_data]
+pub struct Plane<T: DriverPlane> {
+ /// The FFI drm_plane object
+ plane: Opaque<bindings::drm_plane>,
+ /// The driver's private inner data
+ #[pin]
+ inner: T,
+ #[pin]
+ _p: PhantomPinned,
+}
+
+unsafe impl Zeroable for bindings::drm_plane {}
+
+impl<T: DriverPlane> Sealed for Plane<T> {}
+
+impl<T: DriverPlane> Deref for Plane<T> {
+ type Target = T;
+
+ fn deref(&self) -> &Self::Target {
+ &self.inner
+ }
+}
+
+impl<T: DriverPlane> Plane<T> {
+ /// Construct a new [`Plane`].
+ ///
+ /// A driver may use this from their [`Kms::create_objects`] callback in order to construct new
+ /// [`Plane`] objects.
+ ///
+ /// [`Kms::create_objects`]: kernel::drm::kms::Kms::create_objects
+ pub fn new<'a, 'b: 'a, const FMT_COUNT: usize, const MOD_COUNT: usize>(
+ dev: &'a UnregisteredKmsDevice<'a, T::Driver>,
+ possible_crtcs: u32,
+ formats: &'static FormatList<FMT_COUNT>,
+ format_modifiers: Option<&'static ModifierList<MOD_COUNT>>,
+ type_: PlaneType,
+ name: Option<&CStr>,
+ args: T::Args,
+ ) -> Result<&'b Self> {
+ let this: Pin<Box<Self>> = Box::try_pin_init(
+ try_pin_init!(Self {
+ plane: Opaque::new(bindings::drm_plane {
+ helper_private: &T::OPS.helper_funcs,
+ ..Default::default()
+ }),
+ inner <- T::new(dev, args),
+ _p: PhantomPinned
+ }),
+ GFP_KERNEL
+ )?;
+
+ // SAFETY: FFI call with no special requirements
+ to_result(unsafe {
+ bindings::drm_universal_plane_init(
+ dev.as_raw(),
+ this.as_raw(),
+ possible_crtcs,
+ &T::OPS.funcs,
+ formats.as_ptr(),
+ formats.raw_len() as _,
+ format_modifiers.map_or(null(), |f| f.as_ptr()),
+ type_ as _,
+ name.map_or(null(), |n| n.as_char_ptr())
+ )
+ })?;
+
+ // Convert the box into a raw pointer, we'll re-assemble it in plane_destroy_callback()
+ // SAFETY: We don't move anything
+ Ok(unsafe { &*Box::into_raw(Pin::into_inner_unchecked(this)) })
+ }
+}
+
+/// A trait implemented by any type that acts as a [`struct drm_plane`] interface.
+///
+/// This is implemented internally by DRM.
+///
+/// [`struct drm_plane`]: srctree/include/drm/drm_plane.h
+pub trait AsRawPlane: StaticModeObject {
+ /// The type that should be used to represent an atomic state for this plane interface.
+ type State: FromRawPlaneState;
+
+ /// Return the raw `bindings::drm_plane` for this DRM plane.
+ ///
+ /// Drivers should never use this directly.
+ fn as_raw(&self) -> *mut bindings::drm_plane;
+
+ /// Convert a raw `bindings::drm_plane` pointer into an object of this type.
+ ///
+ /// SAFETY: Callers promise that `ptr` points to a valid instance of this type
+ unsafe fn from_raw<'a>(ptr: *mut bindings::drm_plane) -> &'a Self;
+}
+
+impl<T: DriverPlane> AsRawPlane for Plane<T> {
+ type State = PlaneState<T::State>;
+
+ fn as_raw(&self) -> *mut bindings::drm_plane {
+ self.plane.get()
+ }
+
+ unsafe fn from_raw<'a>(ptr: *mut bindings::drm_plane) -> &'a Self {
+ // SAFETY: Our data layout starts with `bindings::drm_plane`
+ unsafe { &*ptr.cast() }
+ }
+}
+
+impl<T: DriverPlane> ModeObject for Plane<T> {
+ type Driver = T::Driver;
+
+ fn drm_dev(&self) -> &Device<Self::Driver> {
+ // SAFETY: DRM planes exist for as long as the device does, so this pointer is always valid
+ unsafe { Device::borrow((*self.as_raw()).dev) }
+ }
+
+ fn raw_mode_obj(&self) -> *mut bindings::drm_mode_object {
+ // SAFETY: We don't expose DRM planes to users before `base` is initialized
+ unsafe { &mut ((*self.as_raw()).base) }
+ }
+}
+
+// SAFETY: Planes do not have a refcount
+unsafe impl<T: DriverPlane> StaticModeObject for Plane<T> {}
+
+// SAFETY: Our interface is thread-safe.
+unsafe impl<T: DriverPlane> Send for Plane<T> {}
+
+// SAFETY: Our interface is thread-safe.
+unsafe impl<T: DriverPlane> Sync for Plane<T> {}
+
+/// A trait implemented by any type which can produce a reference to a [`struct drm_plane_state`].
+///
+/// This is implemented internally by DRM.
+///
+/// [`struct drm_plane_state`]: srctree/include/drm/drm_plane.h
+pub trait AsRawPlaneState: private::AsRawPlaneState {
+ /// The type that this plane state interface returns to represent the parent DRM plane
+ type Plane: AsRawPlane;
+}
+
+pub(crate) mod private {
+ /// Trait for retrieving references to the base plane state contained within any plane state
+ /// compatible type
+ #[doc(hidden)]
+ pub trait AsRawPlaneState {
+ /// Return an immutable reference to the raw plane state
+ fn as_raw(&self) -> &bindings::drm_plane_state;
+
+ /// Get a mutable reference to the raw `bindings::drm_plane_state` contained within this
+ /// type.
+ ///
+ /// # Safety
+ ///
+ /// The caller promises this mutable reference will not be used to modify any contents of
+ /// `bindings::drm_plane_state` which DRM would consider to be static - like the backpointer
+ /// to the DRM plane that owns this state. This also means the mutable reference should
+ /// never be exposed outside of this crate.
+ unsafe fn as_raw_mut(&mut self) -> &mut bindings::drm_plane_state;
+ }
+}
+
+pub(crate) use private::AsRawPlaneState as AsRawPlaneStatePrivate;
+
+/// A trait implemented for any type which can be constructed directly from a
+/// [`struct drm_plane_state`] pointer.
+///
+/// This is implemented internally by DRM.
+///
+/// [`struct drm_plane_state`]: srctree/include/drm/drm_plane.h
+pub trait FromRawPlaneState: AsRawPlaneState {
+ /// Get an immutable reference to this type from the given raw `bindings::drm_plane_state`
+ /// pointer
+ ///
+ /// # Safety
+ ///
+ /// The caller guarantees `ptr` is contained within a valid instance of `Self`
+ unsafe fn from_raw<'a>(ptr: *const bindings::drm_plane_state) -> &'a Self;
+
+ /// Get a mutable reference to this type from the given raw `bindings::drm_plane_state` pointer
+ ///
+ /// # Safety
+ ///
+ /// The caller guarantees `ptr` is contained within a valid instance of `Self`, and that no
+ /// other references (mutable or immutable) to `ptr` exist.
+ unsafe fn from_raw_mut<'a>(ptr: *mut bindings::drm_plane_state) -> &'a mut Self;
+}
+
+/// The main interface for a [`struct drm_plane_state`].
+///
+/// This type is the main interface for dealing with the atomic state of DRM planes. In addition, it
+/// allows access to whatever private data is contained within an implementor's [`DriverPlaneState`]
+/// type.
+///
+/// # Invariants
+///
+/// - The DRM C API and our interface guarantees that only the user has mutable access to `state`,
+/// up until [`drm_atomic_helper_commit_hw_done`] is called. Therefore, `plane` follows rust's
+/// data aliasing rules and does not need to be behind an [`Opaque`] type.
+/// - `state` and `inner` initialized for as long as this object is exposed to users.
+/// - The data layout of this structure begins with [`struct drm_plane_state`].
+/// - The plane for this atomic state can always be assumed to be of type [`Plane<T::Plane>`].
+///
+/// [`struct drm_plane_state`]: srctree/include/drm/drm_plane.h
+/// [`drm_atomic_helper_commit_hw_done`]: srctree/include/drm/drm_atomic_helper.h
+#[derive(Default)]
+#[repr(C)]
+pub struct PlaneState<T: DriverPlaneState> {
+ state: bindings::drm_plane_state,
+ inner: T,
+}
+
+/// The main trait for implementing the [`struct drm_plane_state`] API for a [`Plane`].
+///
+/// A driver may store driver-private data within the implementor's type, which will be available
+/// when using a full typed [`PlaneState`] object.
+///
+/// # Invariants
+///
+/// - Any C FFI callbacks generated using this trait are guaranteed that passed-in
+/// [`struct drm_plane`] pointers are contained within a [`Plane<Self::Plane>`].
+/// - Any C FFI callbacks generated using this trait are guaranteed that passed-in
+/// [`struct drm_plane_state`] pointers are contained within a [`PlaneState<Self>`].
+///
+/// [`struct drm_plane`]: srctree/include/drm_plane.h
+/// [`struct drm_plane_state`]: srctree/include/drm_plane.h
+pub trait DriverPlaneState: Clone + Default + Sized {
+ /// The type for this driver's drm_plane implementation
+ type Plane: DriverPlane;
+}
+
+impl<T: DriverPlaneState> Sealed for PlaneState<T> {}
+
+impl<T: DriverPlaneState> AsRawPlaneState for PlaneState<T> {
+ type Plane = Plane<T::Plane>;
+}
+
+impl<T: DriverPlaneState> private::AsRawPlaneState for PlaneState<T> {
+ fn as_raw(&self) -> &bindings::drm_plane_state {
+ &self.state
+ }
+
+ unsafe fn as_raw_mut(&mut self) -> &mut bindings::drm_plane_state {
+ &mut self.state
+ }
+}
+
+impl<T: DriverPlaneState> FromRawPlaneState for PlaneState<T> {
+ unsafe fn from_raw<'a>(ptr: *const bindings::drm_plane_state) -> &'a Self {
+ // SAFETY: Our data layout starts with `bindings::drm_plane_state`
+ unsafe { &*ptr.cast() }
+ }
+
+ unsafe fn from_raw_mut<'a>(ptr: *mut bindings::drm_plane_state) -> &'a mut Self {
+ // SAFETY: Our data layout starts with `bindings::drm_plane_state`
+ unsafe { &mut *ptr.cast() }
+ }
+}
+
+unsafe impl Zeroable for bindings::drm_plane_state {}
+
+impl<T: DriverPlaneState> Deref for PlaneState<T> {
+ type Target = T;
+
+ fn deref(&self) -> &Self::Target {
+ &self.inner
+ }
+}
+
+impl<T: DriverPlaneState> DerefMut for PlaneState<T> {
+ fn deref_mut(&mut self) -> &mut Self::Target {
+ &mut self.inner
+ }
+}
+
+unsafe extern "C" fn plane_destroy_callback<T: DriverPlane>(
+ plane: *mut bindings::drm_plane
+) {
+ // SAFETY: DRM guarantees that `plane` points to a valid initialized `drm_plane`.
+ unsafe { bindings::drm_plane_cleanup(plane) };
+
+ // SAFETY:
+ // - DRM guarantees we are now the only one with access to this [`drm_plane`].
+ // - This cast is safe via `DriverPlane`s type invariants.
+ drop(unsafe { Box::from_raw(plane as *mut Plane<T>) });
+}
+
+unsafe extern "C" fn atomic_duplicate_state_callback<T: DriverPlaneState>(
+ plane: *mut bindings::drm_plane
+) -> *mut bindings::drm_plane_state {
+ // SAFETY: DRM guarantees that `plane` points to a valid initialized `drm_plane`.
+ let state = unsafe { (*plane).state };
+ if state.is_null() {
+ return null_mut();
+ }
+
+ // SAFETY: This cast is safe via `DriverPlaneState`s type invariants.
+ let state = unsafe { PlaneState::<T>::from_raw(state) };
+
+ let new = Box::try_init(
+ try_init!(PlaneState::<T> {
+ state: bindings::drm_plane_state { ..Default::default() },
+ inner: state.inner.clone()
+ }),
+ GFP_KERNEL
+ );
+
+ if let Ok(mut new) = new {
+ // SAFETY: Just a lil' FFI call, nothing special here
+ unsafe {
+ bindings::__drm_atomic_helper_plane_duplicate_state(plane, new.as_raw_mut())
+ };
+
+ Box::into_raw(new).cast()
+ } else {
+ null_mut()
+ }
+}
+
+unsafe extern "C" fn atomic_destroy_state_callback<T: DriverPlaneState>(
+ _plane: *mut bindings::drm_plane,
+ state: *mut bindings::drm_plane_state
+) {
+ // SAFETY: DRM guarantees that `state` points to a valid instance of `drm_plane_state`
+ unsafe { bindings::__drm_atomic_helper_plane_destroy_state(state) };
+
+ // SAFETY:
+ // * DRM guarantees we are the only one with access to this `drm_plane_state`
+ // * This cast is safe via our type invariants.
+ drop(unsafe { Box::from_raw(state.cast::<PlaneState<T>>()) });
+}
+
+unsafe extern "C" fn plane_reset_callback<T: DriverPlane>(
+ plane: *mut bindings::drm_plane,
+) {
+ // SAFETY: DRM guarantees that `state` points to a valid instance of `drm_plane_state`
+ let state = unsafe { (*plane).state };
+ if !state.is_null() {
+ // SAFETY:
+ // * We're guaranteed `plane` is `Plane<T>` via type invariants
+ // * We're guaranteed `state` is `PlaneState<T>` via type invariants.
+ unsafe { atomic_destroy_state_callback::<T::State>(plane, state) }
+
+ // SAFETY: No special requirements here, DRM expects this to be NULL
+ unsafe { (*plane).state = null_mut(); }
+ }
+
+ // Unfortunately, this is the best we can do at the moment as this FFI callback was mistakenly
+ // presumed to be infallible :(
+ let new = Box::new(PlaneState::<T::State>::default(), GFP_KERNEL)
+ .expect("Blame the API, sorry!");
+
+ // DRM takes ownership of the state from here, resets it, and then assigns it to the plane
+ // SAFETY:
+ // - DRM guarantees that `plane` points to a valid instance of `drm_plane`.
+ // - The cast to `drm_plane_state` is safe via `PlaneState`s type invariants.
+ unsafe { bindings::__drm_atomic_helper_plane_reset(plane, Box::into_raw(new).cast()) };
+}
--
2.46.1
