From 2b6cf19bb5b1ea3ed664300ce1405a8685b6404e Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Sun, 5 Feb 2023 20:58:29 +0900 Subject: rust: drm: file: Add File abstraction A DRM File is the DRM counterpart to a kernel file structure, representing an open DRM file descriptor. Add a Rust abstraction to allow drivers to implement their own File types that implement the DriverFile trait. Signed-off-by: Asahi Lina Signed-off-by: Danilo Krummrich --- rust/bindings/bindings_helper.h | 1 + rust/kernel/drm/device.rs | 4 +- rust/kernel/drm/drv.rs | 3 ++ rust/kernel/drm/file.rs | 116 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/drm/mod.rs | 1 + 5 files changed, 123 insertions(+), 2 deletions(-) create mode 100644 rust/kernel/drm/file.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 503c2e3f6cb9..15e5b1bc7290 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -8,6 +8,7 @@ #include #include +#include #include #include #include diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs index c62516f79221..c6ed8d86700b 100644 --- a/rust/kernel/drm/device.rs +++ b/rust/kernel/drm/device.rs @@ -57,8 +57,8 @@ pub struct Device(Opaque, PhantomData impl Device { const VTABLE: bindings::drm_driver = drm_legacy_fields! { load: None, - open: None, // TODO: File abstraction - postclose: None, // TODO: File abstraction + open: Some(drm::file::open_callback::), + postclose: Some(drm::file::postclose_callback::), lastclose: None, unload: None, release: Some(Self::release), diff --git a/rust/kernel/drm/drv.rs b/rust/kernel/drm/drv.rs index ebb79a8c90ee..895409f04664 100644 --- a/rust/kernel/drm/drv.rs +++ b/rust/kernel/drm/drv.rs @@ -139,6 +139,9 @@ pub trait Driver { /// Should be either `drm::gem::Object` or `drm::gem::shmem::Object`. type Object: AllocImpl; + /// The type used to represent a DRM File (client) + type File: drm::file::DriverFile; + /// Driver metadata const INFO: DriverInfo; diff --git a/rust/kernel/drm/file.rs b/rust/kernel/drm/file.rs new file mode 100644 index 000000000000..0b6366734c61 --- /dev/null +++ b/rust/kernel/drm/file.rs @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +//! DRM File objects. +//! +//! C header: [`include/linux/drm/drm_file.h`](srctree/include/linux/drm/drm_file.h) + +use crate::{bindings, drm, error::Result}; +use alloc::boxed::Box; +use core::marker::PhantomData; +use core::pin::Pin; + +/// Trait that must be implemented by DRM drivers to represent a DRM File (a client instance). +pub trait DriverFile { + /// The parent `Driver` implementation for this `DriverFile`. + type Driver: drm::drv::Driver; + + /// Open a new file (called when a client opens the DRM device). + fn open(device: &drm::device::Device) -> Result>>; +} + +/// An open DRM File. +/// +/// # Invariants +/// `raw` is a valid pointer to a `drm_file` struct. +#[repr(transparent)] +pub struct File { + raw: *mut bindings::drm_file, + _p: PhantomData, +} + +/// The open callback of a `struct drm_file`. +pub(super) unsafe extern "C" fn open_callback( + raw_dev: *mut bindings::drm_device, + raw_file: *mut bindings::drm_file, +) -> core::ffi::c_int { + let drm = unsafe { drm::device::Device::borrow(raw_dev) }; + // SAFETY: This reference won't escape this function + let file = unsafe { &mut *raw_file }; + + let inner = match T::open(drm) { + Err(e) => { + return e.to_errno(); + } + Ok(i) => i, + }; + + // SAFETY: This pointer is treated as pinned, and the Drop guarantee is upheld below. + file.driver_priv = Box::into_raw(unsafe { Pin::into_inner_unchecked(inner) }) as *mut _; + + 0 +} + +/// The postclose callback of a `struct drm_file`. +pub(super) unsafe extern "C" fn postclose_callback( + _raw_dev: *mut bindings::drm_device, + raw_file: *mut bindings::drm_file, +) { + // SAFETY: This reference won't escape this function + let file = unsafe { &*raw_file }; + + // Drop the DriverFile + unsafe { + let _ = Box::from_raw(file.driver_priv as *mut T); + }; +} + +impl File { + // Not intended to be called externally, except via declare_drm_ioctls!() + #[doc(hidden)] + pub unsafe fn from_raw(raw_file: *mut bindings::drm_file) -> File { + File { + raw: raw_file, + _p: PhantomData, + } + } + + #[allow(dead_code)] + /// Return the raw pointer to the underlying `drm_file`. + pub(super) fn raw(&self) -> *const bindings::drm_file { + self.raw + } + + /// Return an immutable reference to the raw `drm_file` structure. + pub(super) fn file(&self) -> &bindings::drm_file { + unsafe { &*self.raw } + } + + /// Return a pinned reference to the driver file structure. + pub fn inner(&self) -> Pin<&T> { + unsafe { Pin::new_unchecked(&*(self.file().driver_priv as *const T)) } + } +} + +impl crate::private::Sealed for File {} + +/// Generic trait to allow users that don't care about driver specifics to accept any `File`. +/// +/// # Safety +/// +/// Must only be implemented for `File` and return the pointer, following the normal invariants +/// of that type. +pub unsafe trait GenericFile: crate::private::Sealed { + /// Returns the raw const pointer to the `struct drm_file` + fn raw(&self) -> *const bindings::drm_file; + /// Returns the raw mut pointer to the `struct drm_file` + fn raw_mut(&mut self) -> *mut bindings::drm_file; +} + +unsafe impl GenericFile for File { + fn raw(&self) -> *const bindings::drm_file { + self.raw + } + fn raw_mut(&mut self) -> *mut bindings::drm_file { + self.raw + } +} diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs index 69376b3c6db9..a767942d0b52 100644 --- a/rust/kernel/drm/mod.rs +++ b/rust/kernel/drm/mod.rs @@ -4,4 +4,5 @@ pub mod device; pub mod drv; +pub mod file; pub mod ioctl; -- cgit v1.2.3-58-ga151