[RFC,3/8] rust: drm: Add Device and Driver abstractions

Message ID	20240520172059.181256-4-dakr@redhat.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <dri-devel-bounces@lists.freedesktop.org> From: Danilo Krummrich <dakr@redhat.com> To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch, ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, fujita.tomonori@gmail.com, lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, gregkh@linuxfoundation.org Cc: rust-for-linux@vger.kernel.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, Danilo Krummrich <dakr@redhat.com> Subject: [RFC PATCH 3/8] rust: drm: Add Device and Driver abstractions Date: Mon, 20 May 2024 19:20:50 +0200 Message-ID: <20240520172059.181256-4-dakr@redhat.com> In-Reply-To: <20240520172059.181256-1-dakr@redhat.com> References: <20240520172059.181256-1-dakr@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true Precedence: list Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" <dri-devel-bounces@lists.freedesktop.org>
Series	DRM Rust abstractions and Nova \| expand [RFC,0/8,RFC] DRM Rust abstractions and Nova [RFC,1/8] rust: drm: ioctl: Add DRM ioctl abstraction [RFC,2/8] rust: Add a Sealed trait [RFC,3/8] rust: drm: Add Device and Driver abstractions [RFC,4/8] rust: drm: implement `AsRef` for DRM device [RFC,5/8] rust: drm: file: Add File abstraction [RFC,6/8] rust: drm: gem: Add GEM object abstraction [RFC,7/8] rust: add firmware abstractions [RFC,8/8] nova: add initial driver stub

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 14188034285a..831fbfe03a47 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -6,6 +6,8 @@ * Sorted alphabetically. */ +#include <drm/drm_device.h> +#include <drm/drm_drv.h> #include <drm/drm_ioctl.h> #include <kunit/test.h> #include <linux/errname.h> diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs new file mode 100644 index 000000000000..f72bab8dd42d --- /dev/null +++ b/rust/kernel/drm/device.rs @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +//! DRM device. +//! +//! C header: [`include/linux/drm/drm_device.h`](../../../../include/linux/drm/drm_device.h) + +use crate::{ + bindings, device, drm, + error::code::*, + error::from_err_ptr, + error::Result, + types::{ARef, AlwaysRefCounted, ForeignOwnable, Opaque}, +}; +use alloc::boxed::Box; +use core::{ffi::c_void, marker::PhantomData, pin::Pin, ptr::NonNull}; + +/// A typed DRM device with a specific driver. The device is always reference-counted. +#[repr(transparent)] +pub struct Device<T: drm::drv::Driver>(Opaque<bindings::drm_device>, PhantomData<T>); + +impl<T: drm::drv::Driver> Device<T> { + pub(crate) fn new( + dev: &device::Device, + vtable: &Pin<Box<bindings::drm_driver>>, + ) -> Result<ARef<Self>> { + let raw_drm = unsafe { bindings::drm_dev_alloc(&**vtable, dev.as_raw()) }; + let raw_drm = NonNull::new(from_err_ptr(raw_drm)? as *mut _).ok_or(ENOMEM)?; + + // SAFETY: The reference count is one, and now we take ownership of that reference as a + // drm::device::Device. + Ok(unsafe { ARef::from_raw(raw_drm) }) + } + + pub(crate) fn as_raw(&self) -> *mut bindings::drm_device { + self.0.get() + } + + // Not intended to be called externally, except via declare_drm_ioctls!() + #[doc(hidden)] + pub unsafe fn borrow<'a>(raw: *const bindings::drm_device) -> &'a Self { + unsafe { &*(raw as *const Self) } + } + + pub(crate) fn raw_data(&self) -> *const c_void { + // SAFETY: `self` is guaranteed to hold a valid `bindings::drm_device` pointer. + unsafe { *self.as_raw() }.dev_private + } + + // SAFETY: Must be called only once after device creation. + pub(crate) unsafe fn set_raw_data(&self, ptr: *const c_void) { + // SAFETY: Safe as by the safety precondition. + unsafe { &mut *self.as_raw() }.dev_private = ptr as _; + } + + /// Returns a borrowed reference to the user data associated with this Device. + pub fn data(&self) -> Option<<T::Data as ForeignOwnable>::Borrowed<'_>> { + let dev_private = self.raw_data(); + + if dev_private.is_null() { + None + } else { + // SAFETY: `dev_private` is NULL before the DRM device is registered; after the DRM + // device has been registered dev_private is guaranteed to be valid. + Some(unsafe { T::Data::borrow(dev_private) }) + } + } +} + +// SAFETY: DRM device objects are always reference counted and the get/put functions +// satisfy the requirements. +unsafe impl<T: drm::drv::Driver> AlwaysRefCounted for Device<T> { + fn inc_ref(&self) { + unsafe { bindings::drm_dev_get(&self.as_raw() as *const _ as *mut _) }; + } + + unsafe fn dec_ref(obj: NonNull<Self>) { + // SAFETY: The Device<T> type has the same layout as drm_device, so we can just cast. + unsafe { bindings::drm_dev_put(obj.as_ptr() as *mut _) }; + } +} + +// SAFETY: `Device` only holds a pointer to a C device, which is safe to be used from any thread. +unsafe impl<T: drm::drv::Driver> Send for Device<T> {} + +// SAFETY: `Device` only holds a pointer to a C device, references to which are safe to be used +// from any thread. +unsafe impl<T: drm::drv::Driver> Sync for Device<T> {} diff --git a/rust/kernel/drm/drv.rs b/rust/kernel/drm/drv.rs new file mode 100644 index 000000000000..5dd8f3f8df7c --- /dev/null +++ b/rust/kernel/drm/drv.rs @@ -0,0 +1,318 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +//! DRM driver core. +//! +//! C header: [`include/linux/drm/drm_drv.h`](../../../../include/linux/drm/drm_drv.h) + +use crate::{ + alloc::flags::*, + bindings, device, drm, + error::code::*, + error::{Error, Result}, + prelude::*, + private::Sealed, + str::CStr, + types::{ARef, ForeignOwnable}, + ThisModule, +}; +use core::{ + marker::{PhantomData, PhantomPinned}, + pin::Pin, +}; +use macros::vtable; + +/// Driver use the GEM memory manager. This should be set for all modern drivers. +pub const FEAT_GEM: u32 = bindings::drm_driver_feature_DRIVER_GEM; +/// Driver supports mode setting interfaces (KMS). +pub const FEAT_MODESET: u32 = bindings::drm_driver_feature_DRIVER_MODESET; +/// Driver supports dedicated render nodes. +pub const FEAT_RENDER: u32 = bindings::drm_driver_feature_DRIVER_RENDER; +/// Driver supports the full atomic modesetting userspace API. +/// +/// Drivers which only use atomic internally, but do not support the full userspace API (e.g. not +/// all properties converted to atomic, or multi-plane updates are not guaranteed to be tear-free) +/// should not set this flag. +pub const FEAT_ATOMIC: u32 = bindings::drm_driver_feature_DRIVER_ATOMIC; +/// Driver supports DRM sync objects for explicit synchronization of command submission. +pub const FEAT_SYNCOBJ: u32 = bindings::drm_driver_feature_DRIVER_SYNCOBJ; +/// Driver supports the timeline flavor of DRM sync objects for explicit synchronization of command +/// submission. +pub const FEAT_SYNCOBJ_TIMELINE: u32 = bindings::drm_driver_feature_DRIVER_SYNCOBJ_TIMELINE; + +/// Information data for a DRM Driver. +pub struct DriverInfo { + /// Driver major version. + pub major: i32, + /// Driver minor version. + pub minor: i32, + /// Driver patchlevel version. + pub patchlevel: i32, + /// Driver name. + pub name: &'static CStr, + /// Driver description. + pub desc: &'static CStr, + /// Driver date. + pub date: &'static CStr, +} + +/// Internal memory management operation set, normally created by memory managers (e.g. GEM). +/// +/// See `kernel::drm::gem` and `kernel::drm::gem::shmem`. +pub struct AllocOps { + pub(crate) gem_create_object: Option< + unsafe extern "C" fn( + dev: *mut bindings::drm_device, + size: usize, + ) -> *mut bindings::drm_gem_object, + >, + pub(crate) prime_handle_to_fd: Option< + unsafe extern "C" fn( + dev: *mut bindings::drm_device, + file_priv: *mut bindings::drm_file, + handle: u32, + flags: u32, + prime_fd: *mut core::ffi::c_int, + ) -> core::ffi::c_int, + >, + pub(crate) prime_fd_to_handle: Option< + unsafe extern "C" fn( + dev: *mut bindings::drm_device, + file_priv: *mut bindings::drm_file, + prime_fd: core::ffi::c_int, + handle: *mut u32, + ) -> core::ffi::c_int, + >, + pub(crate) gem_prime_import: Option< + unsafe extern "C" fn( + dev: *mut bindings::drm_device, + dma_buf: *mut bindings::dma_buf, + ) -> *mut bindings::drm_gem_object, + >, + pub(crate) gem_prime_import_sg_table: Option< + unsafe extern "C" fn( + dev: *mut bindings::drm_device, + attach: *mut bindings::dma_buf_attachment, + sgt: *mut bindings::sg_table, + ) -> *mut bindings::drm_gem_object, + >, + pub(crate) dumb_create: Option< + unsafe extern "C" fn( + file_priv: *mut bindings::drm_file, + dev: *mut bindings::drm_device, + args: *mut bindings::drm_mode_create_dumb, + ) -> core::ffi::c_int, + >, + pub(crate) dumb_map_offset: Option< + unsafe extern "C" fn( + file_priv: *mut bindings::drm_file, + dev: *mut bindings::drm_device, + handle: u32, + offset: *mut u64, + ) -> core::ffi::c_int, + >, +} + +/// Trait for memory manager implementations. Implemented internally. +pub trait AllocImpl: Sealed { + /// The C callback operations for this memory manager. + const ALLOC_OPS: AllocOps; +} + +/// A DRM driver implementation. +#[vtable] +pub trait Driver { + /// Context data associated with the DRM driver + /// + /// Determines the type of the context data passed to each of the methods of the trait. + type Data: ForeignOwnable + Sync + Send; + + /// The type used to manage memory for this driver. + /// + /// Should be either `drm::gem::Object<T>` or `drm::gem::shmem::Object<T>`. + type Object: AllocImpl; + + /// Driver metadata + const INFO: DriverInfo; + + /// Feature flags + const FEATURES: u32; + + /// IOCTL list. See `kernel::drm::ioctl::declare_drm_ioctls!{}`. + const IOCTLS: &'static [drm::ioctl::DrmIoctlDescriptor]; +} + +/// A registration of a DRM device +/// +/// # Invariants: +/// +/// drm is always a valid pointer to an allocated drm_device +pub struct Registration<T: Driver> { + drm: ARef<drm::device::Device<T>>, + registered: bool, + fops: bindings::file_operations, + vtable: Pin<Box<bindings::drm_driver>>, + _p: PhantomData<T>, + _pin: PhantomPinned, +} + +#[cfg(CONFIG_DRM_LEGACY)] +macro_rules! drm_legacy_fields { + ( $($field:ident: $val:expr),* $(,)? ) => { + bindings::drm_driver { + $( $field: $val ),*, + firstopen: None, + preclose: None, + dma_ioctl: None, + dma_quiescent: None, + context_dtor: None, + irq_handler: None, + irq_preinstall: None, + irq_postinstall: None, + irq_uninstall: None, + get_vblank_counter: None, + enable_vblank: None, + disable_vblank: None, + dev_priv_size: 0, + } + } +} + +#[cfg(not(CONFIG_DRM_LEGACY))] +macro_rules! drm_legacy_fields { + ( $($field:ident: $val:expr),* $(,)? ) => { + bindings::drm_driver { + $( $field: $val ),* + } + } +} + +/// Registers a DRM device with the rest of the kernel. +/// +/// It automatically picks up THIS_MODULE. +#[allow(clippy::crate_in_macro_def)] +#[macro_export] +macro_rules! drm_device_register { + ($reg:expr, $data:expr, $flags:expr $(,)?) => {{ + $crate::drm::drv::Registration::register($reg, $data, $flags, &crate::THIS_MODULE) + }}; +} + +impl<T: Driver> Registration<T> { + const VTABLE: bindings::drm_driver = drm_legacy_fields! { + load: None, + open: None, // TODO: File abstraction + postclose: None, // TODO: File abstraction + lastclose: None, + unload: None, + release: None, + master_set: None, + master_drop: None, + debugfs_init: None, + gem_create_object: T::Object::ALLOC_OPS.gem_create_object, + prime_handle_to_fd: T::Object::ALLOC_OPS.prime_handle_to_fd, + prime_fd_to_handle: T::Object::ALLOC_OPS.prime_fd_to_handle, + gem_prime_import: T::Object::ALLOC_OPS.gem_prime_import, + gem_prime_import_sg_table: T::Object::ALLOC_OPS.gem_prime_import_sg_table, + dumb_create: T::Object::ALLOC_OPS.dumb_create, + dumb_map_offset: T::Object::ALLOC_OPS.dumb_map_offset, + show_fdinfo: None, + + major: T::INFO.major, + minor: T::INFO.minor, + patchlevel: T::INFO.patchlevel, + name: T::INFO.name.as_char_ptr() as *mut _, + desc: T::INFO.desc.as_char_ptr() as *mut _, + date: T::INFO.date.as_char_ptr() as *mut _, + + driver_features: T::FEATURES, + ioctls: T::IOCTLS.as_ptr(), + num_ioctls: T::IOCTLS.len() as i32, + fops: core::ptr::null_mut(), + }; + + /// Creates a new [`Registration`] but does not register it yet. + /// + /// It is allowed to move. + pub fn new(parent: &device::Device) -> Result<Self> { + let vtable = Pin::new(Box::new(Self::VTABLE, GFP_KERNEL)?); + + Ok(Self { + drm: drm::device::Device::new(parent, &vtable)?, + registered: false, + vtable, + fops: Default::default(), // TODO: GEM abstraction + _pin: PhantomPinned, + _p: PhantomData, + }) + } + + /// Registers a DRM device with the rest of the kernel. + /// + /// Users are encouraged to use the [`drm_device_register!()`] macro because it automatically + /// picks up the current module. + pub fn register( + self: Pin<&mut Self>, + data: T::Data, + flags: usize, + module: &'static ThisModule, + ) -> Result { + if self.registered { + // Already registered. + return Err(EINVAL); + } + + // SAFETY: We never move out of `this`. + let this = unsafe { self.get_unchecked_mut() }; + let data_pointer = <T::Data as ForeignOwnable>::into_foreign(data); + + // SAFETY: This is the only code touching a device' private data pointer. + unsafe { this.drm.set_raw_data(data_pointer) }; + + this.fops.owner = module.0; + this.vtable.fops = &this.fops; + + // SAFETY: The device is now initialized and ready to be registered. + let ret = unsafe { bindings::drm_dev_register(this.drm.as_raw(), flags as u64) }; + if ret < 0 { + // SAFETY: `data_pointer` was returned by `into_foreign` above. + unsafe { T::Data::from_foreign(data_pointer) }; + return Err(Error::from_errno(ret)); + } + + this.registered = true; + Ok(()) + } + + /// Returns a reference to the `Device` instance for this registration. + pub fn device(&self) -> &drm::device::Device<T> { + &self.drm + } +} + +// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads +// or CPUs, so it is safe to share it. +unsafe impl<T: Driver> Sync for Registration<T> {} + +// SAFETY: Registration with and unregistration from the drm subsystem can happen from any thread. +// Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is ok to move +// `Registration` to different threads. +#[allow(clippy::non_send_fields_in_send_ty)] +unsafe impl<T: Driver> Send for Registration<T> {} + +impl<T: Driver> Drop for Registration<T> { + /// Removes the registration from the kernel if it has completed successfully before. + fn drop(&mut self) { + if self.registered { + // Get a pointer to the data stored in device before destroying it. + // SAFETY: `drm` is valid per the type invariant + let data_pointer = self.drm.raw_data(); + + // SAFETY: Since `registered` is true, `self.drm` is both valid and registered. + unsafe { bindings::drm_dev_unregister(self.drm.as_raw()) }; + + // Free data as well. + // SAFETY: `data_pointer` was returned by `into_foreign` during registration. + unsafe { <T::Data as ForeignOwnable>::from_foreign(data_pointer) }; + } + } +} diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs index 9ec6d7cbcaf3..69376b3c6db9 100644 --- a/rust/kernel/drm/mod.rs +++ b/rust/kernel/drm/mod.rs @@ -2,4 +2,6 @@ //! DRM subsystem abstractions. +pub mod device; +pub mod drv; pub mod ioctl;

[RFC,3/8] rust: drm: Add Device and Driver abstractions

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