Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 758DFC678D5 for ; Tue, 7 Mar 2023 14:31:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229881AbjCGObn (ORCPT ); Tue, 7 Mar 2023 09:31:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229898AbjCGOa6 (ORCPT ); Tue, 7 Mar 2023 09:30:58 -0500 Received: from mail.marcansoft.com (marcansoft.com [212.63.210.85]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B1BF888BF; Tue, 7 Mar 2023 06:26:56 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: linasend@asahilina.net) by mail.marcansoft.com (Postfix) with ESMTPSA id EFF01420D8; Tue, 7 Mar 2023 14:26:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=asahilina.net; s=default; t=1678199215; bh=ybXc676YDutsjlMaSuuenGoZJO/fukuHqULLdgV/v/M=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=OpjjgA7LC7q4Glsexbn+nW/mRuBv6rhD+pd1NYciXMLw6u+H1RakS8DC5sXggG0cG Yd7SjxsIlxh0AkS1OthspkDO4sz81hphi9x5hXBrb9l/LKUV4XxP5Dr6x0Bv1VN7QJ JPOYSKEkvlAHwMATnLAjSaRiCKmnokEd6OTQ0Mu0ay6GhsN1g+hUgG/simriZqZCsB XPcBmLMCgB8rUy+OQn8gKjvKQg1SAGrorvM6lQgXslEQ3cdS94LXjOjhrOIoaeqrUB ASxFLNkLA2ydu5CGN9DDkJlr3E2Ck/1gD0mzAb3jDjmuc4YM1C3WPKe/AianXlSmwS Cg3r/1An4X4Dg== From: Asahi Lina Date: Tue, 07 Mar 2023 23:25:27 +0900 Subject: [PATCH RFC 02/18] rust: drm: Add Device and Driver abstractions MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20230307-rust-drm-v1-2-917ff5bc80a8@asahilina.net> References: <20230307-rust-drm-v1-0-917ff5bc80a8@asahilina.net> In-Reply-To: <20230307-rust-drm-v1-0-917ff5bc80a8@asahilina.net> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Luben Tuikov , Jarkko Sakkinen , Dave Hansen Cc: Alyssa Rosenzweig , Karol Herbst , Ella Stanforth , Faith Ekstrand , Mary , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-sgx@vger.kernel.org, asahi@lists.linux.dev, Asahi Lina X-Mailer: b4 0.12.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1678199191; l=16844; i=lina@asahilina.net; s=20230221; h=from:subject:message-id; bh=ybXc676YDutsjlMaSuuenGoZJO/fukuHqULLdgV/v/M=; b=ZAJvSXMpknOJW8GmoecAuTMvhH+w8WU/LojoH//ra2xRSLnc2949i7/QPHqsvsnwzxoW56X/r CCeFhXwJVd9AxNJFrQPow+MTQsL1NH1jvQhvrIsCC5yTlyWY2NPGHs8 X-Developer-Key: i=lina@asahilina.net; a=ed25519; pk=Qn8jZuOtR1m5GaiDfTrAoQ4NE1XoYVZ/wmt5YtXWFC4= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add the initial abstractions for DRM drivers and devices. These go together in one commit since they are fairly tightly coupled types. A few things have been stubbed out, to be implemented as further bits of the DRM subsystem are introduced. Signed-off-by: Asahi Lina --- rust/bindings/bindings_helper.h | 3 + rust/kernel/drm/device.rs | 76 +++++++++ rust/kernel/drm/drv.rs | 339 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/drm/mod.rs | 2 + 4 files changed, 420 insertions(+) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 2687bef1676f..2a999138c4ae 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -6,10 +6,13 @@ * Sorted alphabetically. */ +#include +#include #include #include #include #include +#include #include #include #include diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs new file mode 100644 index 000000000000..6007f941137a --- /dev/null +++ b/rust/kernel/drm/device.rs @@ -0,0 +1,76 @@ +// 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, types::ForeignOwnable}; +use core::marker::PhantomData; + +/// Represents a reference to a DRM device. The device is reference-counted and is guaranteed to +/// not be dropped while this object is alive. +pub struct Device { + // Type invariant: ptr must be a valid and initialized drm_device, + // and this value must either own a reference to it or the caller + // must ensure that it is never dropped if the reference is borrowed. + pub(super) ptr: *mut bindings::drm_device, + _p: PhantomData, +} + +impl Device { + // Not intended to be called externally, except via declare_drm_ioctls!() + #[doc(hidden)] + pub unsafe fn from_raw(raw: *mut bindings::drm_device) -> Device { + Device { + ptr: raw, + _p: PhantomData, + } + } + + #[allow(dead_code)] + pub(crate) fn raw(&self) -> *const bindings::drm_device { + self.ptr + } + + pub(crate) fn raw_mut(&mut self) -> *mut bindings::drm_device { + self.ptr + } + + /// Returns a borrowed reference to the user data associated with this Device. + pub fn data(&self) -> ::Borrowed<'_> { + unsafe { T::Data::borrow((*self.ptr).dev_private) } + } +} + +impl Drop for Device { + fn drop(&mut self) { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // relinquish it now. + unsafe { bindings::drm_dev_put(self.ptr) }; + } +} + +impl Clone for Device { + fn clone(&self) -> Self { + // SAFETY: We get a new reference and then create a new owning object from the raw pointer + unsafe { + bindings::drm_dev_get(self.ptr); + Device::from_raw(self.ptr) + } + } +} + +// SAFETY: `Device` only holds a pointer to a C device, which is safe to be used from any thread. +unsafe impl Send for Device {} + +// SAFETY: `Device` only holds a pointer to a C device, references to which are safe to be used +// from any thread. +unsafe impl Sync for Device {} + +// Make drm::Device work for dev_info!() and friends +unsafe impl device::RawDevice for Device { + fn raw_device(&self) -> *mut bindings::device { + // SAFETY: ptr must be valid per the type invariant + unsafe { (*self.ptr).dev } + } +} diff --git a/rust/kernel/drm/drv.rs b/rust/kernel/drm/drv.rs new file mode 100644 index 000000000000..29a465515dc9 --- /dev/null +++ b/rust/kernel/drm/drv.rs @@ -0,0 +1,339 @@ +// 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::{ + bindings, device, drm, + error::code::*, + error::from_kernel_err_ptr, + error::{Error, Result}, + prelude::*, + private::Sealed, + str::CStr, + types::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) gem_prime_mmap: Option< + unsafe extern "C" fn( + obj: *mut bindings::drm_gem_object, + vma: *mut bindings::vm_area_struct, + ) -> core::ffi::c_int, + >, + 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, + >, + pub(crate) dumb_destroy: Option< + unsafe extern "C" fn( + file_priv: *mut bindings::drm_file, + dev: *mut bindings::drm_device, + handle: u32, + ) -> 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` or `drm::gem::shmem::Object`. + 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 { + drm: drm::device::Device, + registered: bool, + fops: bindings::file_operations, + vtable: Pin>, + _p: PhantomData, + _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 Registration { + 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, + gem_prime_mmap: T::Object::ALLOC_OPS.gem_prime_mmap, + dumb_create: T::Object::ALLOC_OPS.dumb_create, + dumb_map_offset: T::Object::ALLOC_OPS.dumb_map_offset, + dumb_destroy: T::Object::ALLOC_OPS.dumb_destroy, + + 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: &dyn device::RawDevice) -> Result { + let vtable = Pin::new(Box::try_new(Self::VTABLE)?); + let raw_drm = unsafe { bindings::drm_dev_alloc(&*vtable, parent.raw_device()) }; + let raw_drm = from_kernel_err_ptr(raw_drm)?; + + // The reference count is one, and now we take ownership of that reference as a + // drm::device::Device. + let drm = unsafe { drm::device::Device::from_raw(raw_drm) }; + + Ok(Self { + drm, + 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 = ::into_foreign(data); + // SAFETY: `drm` is valid per the type invariant + unsafe { + (*this.drm.raw_mut()).dev_private = data_pointer as *mut _; + } + + 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.raw_mut(), 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_kernel_errno(ret)); + } + + this.registered = true; + Ok(()) + } + + /// Returns a reference to the `Device` instance for this registration. + pub fn device(&self) -> &drm::device::Device { + &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 Sync for Registration {} + +// 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 Send for Registration {} + +impl Drop for Registration { + /// 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 = unsafe { (*self.drm.raw_mut()).dev_private }; + + // SAFETY: Since `registered` is true, `self.drm` is both valid and registered. + unsafe { bindings::drm_dev_unregister(self.drm.raw_mut()) }; + + // Free data as well. + // SAFETY: `data_pointer` was returned by `into_foreign` during registration. + unsafe { ::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; -- 2.35.1