From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A18C20F09C; Wed, 16 Jul 2025 15:04:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752678256; cv=none; b=rdEwlVjhEfNKRmmgX5mLyuMpySF4U2yPb4vD3HXtQrh8H1cfkWcdqISfM7gXqJAwaU2T9n29vG2oetqJQ06cI4NKZNptTM/zNx0HdmrCD9eieJdK5T88IrPCxEmz3T4htaXBRGLwyT1szwTmZ7hF4URZ9nzJN3kG8fNpb9vIdiU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752678256; c=relaxed/simple; bh=Jm5T7wVKYwNR2zjbQ2WIR5doSI9DWAxN08adyYuf1CE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dPeXwkA7lwUmb/AxldBfFy7e4uBryApqGpO9voY1OeeNtGM/d00p9dM4YkjbzbhgoJlszjbyz6u2szAE3Djs9afT3crWRaCFW7uFYIsh3svFKYT58Sy1t/q/E1Ct76h1s8cOQlMxpa2w4gtxKXHhuM+sIz+Ubi1AONxfpV78oDw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WhohAihk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WhohAihk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 237E1C4CEEB; Wed, 16 Jul 2025 15:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752678256; bh=Jm5T7wVKYwNR2zjbQ2WIR5doSI9DWAxN08adyYuf1CE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WhohAihksFx6OOtIMBZKbF2jkPU9rlxI8d4iurjp/JHuSnbB6iL9bg6UNODiIZUKO blcOI3CmG+HvsJL00yWrk1GGruV5ce3C2kjx8zPvr2FuYollvuw++v9Kph+SZIXGJm d+rW1wEQE0/s9UQ54mBzIJYqgR6a4xnmRVb3458f0ZniioIohNHAzSWvYEJgB8n17Z 3Ddz+vpPrafKxSR8BxE8YP6b/Yo1FHQX3kMvELEUQElgc0woCY7H7jB4vTxnlOMJSz 8G/WdDO7G9HZyly7ggzbi0dpjI6BT8RqP1k/jX3upxjaLnjrRSq/pH+bEVgoVVnwXG Ic2xDpdmuAqMQ== From: Danilo Krummrich To: abdiel.janulgue@gmail.com, daniel.almeida@collabora.com, robin.murphy@arm.com, a.hindborg@kernel.org, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, aliceryhl@google.com, tmgross@umich.edu, bhelgaas@google.com, kwilczynski@kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org Cc: rust-for-linux@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: [PATCH v2 2/5] rust: dma: add DMA addressing capabilities Date: Wed, 16 Jul 2025 17:02:47 +0200 Message-ID: <20250716150354.51081-3-dakr@kernel.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250716150354.51081-1-dakr@kernel.org> References: <20250716150354.51081-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Implement `dma_set_mask()`, `dma_set_coherent_mask()` and `dma_set_mask_and_coherent()` in the `dma::Device` trait. Those methods are used to set up the device's DMA addressing capabilities. Reviewed-by: Abdiel Janulgue Signed-off-by: Danilo Krummrich --- rust/helpers/dma.c | 5 ++ rust/kernel/dma.rs | 112 +++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 113 insertions(+), 4 deletions(-) diff --git a/rust/helpers/dma.c b/rust/helpers/dma.c index df8b8a77355a..6e741c197242 100644 --- a/rust/helpers/dma.c +++ b/rust/helpers/dma.c @@ -14,3 +14,8 @@ void rust_helper_dma_free_attrs(struct device *dev, size_t size, void *cpu_addr, { dma_free_attrs(dev, size, cpu_addr, dma_handle, attrs); } + +int rust_helper_dma_set_mask_and_coherent(struct device *dev, u64 mask) +{ + return dma_set_mask_and_coherent(dev, mask); +} diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs index f0af23d08e8d..afd3ba538e3c 100644 --- a/rust/kernel/dma.rs +++ b/rust/kernel/dma.rs @@ -6,9 +6,9 @@ use crate::{ bindings, build_assert, device, - device::Bound, - error::code::*, - error::Result, + device::{Bound, Core}, + error::{to_result, Result}, + prelude::*, transmute::{AsBytes, FromBytes}, types::ARef, }; @@ -18,7 +18,111 @@ /// The [`dma::Device`](Device) trait should be implemented by bus specific device representations, /// where the underlying bus is DMA capable, such as [`pci::Device`](::kernel::pci::Device) or /// [`platform::Device`](::kernel::platform::Device). -pub trait Device: AsRef> {} +pub trait Device: AsRef> { + /// Set up the device's DMA streaming addressing capabilities. + /// + /// This method is usually called once from `probe()` as soon as the device capabilities are + /// known. + /// + /// # Safety + /// + /// This method must not be called concurrently with any DMA allocation or mapping primitives, + /// such as [`CoherentAllocation::alloc_attrs`]. + unsafe fn dma_set_mask(&self, mask: DmaMask) -> Result { + // SAFETY: + // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. + // - The safety requirement of this function guarantees that there are no concurrent calls + // to DMA allocation and mapping primitives using this mask. + to_result(unsafe { bindings::dma_set_mask(self.as_ref().as_raw(), mask.value()) }) + } + + /// Set up the device's DMA coherent addressing capabilities. + /// + /// This method is usually called once from `probe()` as soon as the device capabilities are + /// known. + /// + /// # Safety + /// + /// This method must not be called concurrently with any DMA allocation or mapping primitives, + /// such as [`CoherentAllocation::alloc_attrs`]. + unsafe fn dma_set_coherent_mask(&self, mask: DmaMask) -> Result { + // SAFETY: + // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. + // - The safety requirement of this function guarantees that there are no concurrent calls + // to DMA allocation and mapping primitives using this mask. + to_result(unsafe { bindings::dma_set_coherent_mask(self.as_ref().as_raw(), mask.value()) }) + } + + /// Set up the device's DMA addressing capabilities. + /// + /// This is a combination of [`Device::dma_set_mask`] and [`Device::dma_set_coherent_mask`]. + /// + /// This method is usually called once from `probe()` as soon as the device capabilities are + /// known. + /// + /// # Safety + /// + /// This method must not be called concurrently with any DMA allocation or mapping primitives, + /// such as [`CoherentAllocation::alloc_attrs`]. + unsafe fn dma_set_mask_and_coherent(&self, mask: DmaMask) -> Result { + // SAFETY: + // - By the type invariant of `device::Device`, `self.as_ref().as_raw()` is valid. + // - The safety requirement of this function guarantees that there are no concurrent calls + // to DMA allocation and mapping primitives using this mask. + to_result(unsafe { + bindings::dma_set_mask_and_coherent(self.as_ref().as_raw(), mask.value()) + }) + } +} + +/// A DMA mask that holds a bitmask with the lowest `n` bits set. +/// +/// Use [`DmaMask::new`] to construct a value. Values are guaranteed to +/// never exceed the bit width of `u64`. +/// +/// This is the Rust equivalent of the C macro `DMA_BIT_MASK()`. +/// +/// # Examples +/// +/// ``` +/// use kernel::dma::DmaMask; +/// +/// let mask0 = DmaMask::new(0)?; +/// assert_eq!(mask0.value(), 0); +/// +/// let mask1 = DmaMask::new(1)?; +/// assert_eq!(mask1.value(), 0b1); +/// +/// let mask64 = DmaMask::new(64)?; +/// assert_eq!(mask64.value(), u64::MAX); +/// +/// let mask_overflow = DmaMask::new(100); +/// assert!(mask_overflow.is_err()); +/// # Ok::<(), Error>(()) +/// ``` +#[derive(Debug, Clone, Copy, PartialEq, Eq)] +pub struct DmaMask(u64); + +impl DmaMask { + /// Constructs a `DmaMask` with the lowest `n` bits set to `1`. + /// + /// For `n <= 64`, sets exactly the lowest `n` bits. + /// For `n > 64`, returns [`EINVAL`]. + #[inline] + pub const fn new(n: usize) -> Result { + Ok(Self(match n { + 0 => 0, + 1..=64 => u64::MAX >> (64 - n), + _ => return Err(EINVAL), + })) + } + + /// Returns the underlying `u64` bitmask value. + #[inline] + pub const fn value(&self) -> u64 { + self.0 + } +} /// Possible attributes associated with a DMA mapping. /// -- 2.50.0