From nobody Sun Feb 8 01:31:21 2026 Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) (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 5C38D31D75C for ; Mon, 27 Oct 2025 20:06:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.66 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761595576; cv=none; b=U8aCEzcpnyy5CtBmXp3Kskib7optxBA7WrQS3HTysj4p2cWfNFZVqhlj4HsXk1/w/Enw4R9uXCTF3FhOwC3+ydDMdIrSEnr/plao2BINXjV9nN6JH0FOoIr0/92oAZrtaAMVHC7Wlhl2o0tkAX7S60uisOLZeP08diNPBNCjVB4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761595576; c=relaxed/simple; bh=Garq7VO1PdQbR41KtGI+fTjLqRCsro5auWy0YdckOkA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qsuMPBsaxlscmsYRXGTrI9bEvkCXn22N2eCYVdBT4hWqgmoYHQgrQybWd/3z8s2qda9y8f6H//jj75MONQbdmcGTHhVQSceWi5/yp5iIVV85ABSLGALO36SAcSq5P554gA7xtWyHiN8l0++sevxNmoWbehEA4VG9RUgZE8ZnMFc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=rw3RPwDt; arc=none smtp.client-ip=185.67.36.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="rw3RPwDt" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id A99C8240103 for ; Mon, 27 Oct 2025 21:06:04 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1761595564; bh=qm2cnUKzVLRN3dgzzMumdrxbcUv5Pqw48DSmrrD/IkA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:Autocrypt:OpenPGP:From; b=rw3RPwDt/YxYgLLxXZ2ONVrAStx5KO+CBvD9+W0to1J8a+hxm23dYa922qw0SGodV lyKMxv3UIPmQ5PArWvOyh9v1saLrH5a+czSZD9bCVtoN5PzOsNcSJwhVGGsaVFKoZ+ mCgHLCWhOYE5op5WTENznHLGWaNt3ouVz/95ocibAtiLXuOo67VNNgT3mPPUstwVUd bgyKv3yW9ukRc5GZWFOvigM8YJQTmJ735g6F3AteI1DVxb5hdOB3QJA3XIAE3oBHB2 JPBS0rJIUnUIitumVipuFsQBEn0MiGWdC8DmZNBJs63kpEAxdKjeezSpEJOjGDNWl+ YCaAPtCnzqnkw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4cwPdj0nD4z9rxK; Mon, 27 Oct 2025 21:06:01 +0100 (CET) From: Markus Probst To: Greg Kroah-Hartman , Miguel Ojeda , Alex Gaynor , Danilo Krummrich , "Rafael J. Wysocki" , Lee Jones , Pavel Machek Cc: Dave Ertman , Ira Weiny , Leon Romanovsky , Boqun Feng , Gary Guo , bjorn3_gh@protonmail.com, Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Bjorn Helgaas , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Markus Probst , rust-for-linux@vger.kernel.org, linux-leds@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 1/2] rust: Add trait to convert a device reference to a bus device reference Date: Mon, 27 Oct 2025 20:06:03 +0000 Message-ID: <20251027200547.1038967-2-markus.probst@posteo.de> In-Reply-To: <20251027200547.1038967-1-markus.probst@posteo.de> References: <20251027200547.1038967-1-markus.probst@posteo.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5573; i=markus.probst@posteo.de; h=from:subject; bh=Garq7VO1PdQbR41KtGI+fTjLqRCsro5auWy0YdckOkA=; b=owEBbQKS/ZANAwAIATR2H/jnrUPSAcsmYgBo/9B7gUvu7Zhh52kQWYQjztQ4KWXF/nHONfwKs xNpc2Z3Qi+JAjMEAAEIAB0WIQSCdBjE9KxY53IwxHM0dh/4561D0gUCaP/QewAKCRA0dh/4561D 0luND/4tPX7HQmtzU6jLks8vsqblaucYlVLZWnkZpTZbv7qGBd5//essk+V+y3d3M7gu/I/v5LU GXOyDzARcd5Bcl0zAx3uMZPvMf1mOsUQYxQxeMJmcJO8cvw1KObGuowwNHlLHI0U9ddEawkYuhW CRz3koY7rFnh1XdodHyEPR+ziHK925qLZNpVDWYLiMayGiX/PppZVXshbVGiBApvoe59y5Rd9R5 FFqqzwoXfHNpDtHbNQtePB7icdfxWHTu4jNvznMZ9LtNe5zNBymNVQQxdFdstcxeHEb4Rtnk8Mw cWdi1fa2J3SpWISg2/pFJJhhzAgsrIMCu4eobWB3JXkRf6moLJZcx3JZ9it6t/lH/Qx+vgVghUg KTUh4MEPPLwN1epxGsObGizRVZ/M5e+Cqcprp0VMskXV6nefuX5QRoCxIxP+uheGfxQmmMR9KDB zZjRrb7LE4IJidBRXjZo2F4rddebWnfpS816ELbKBst/cWNJysXAQW+DCmvi0yNBeej90kHHMwy Z8UucOJ4JrBUW3OY1gwavEpud1pnaJna3+k+xYfx+do934cO7xum/ggyUoq04YEKnjqunx2Wad9 SEJygnZU55re+Pps77Zw2ntiW5RbUko4HlsFkTwCSd9YYVMTmtCfErEaiq6Kw3Yy83E80d6KoCM Db2oMjDQ3WCDE0A= = X-Developer-Key: i=markus.probst@posteo.de; a=openpgp; fpr=827418C4F4AC58E77230C47334761FF8E7AD43D2 Content-Transfer-Encoding: quoted-printable Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=xsFNBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93qReNLkO WguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVAm76Ww+ /pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt9k5JA RhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbmfAja oT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwTjRQ xBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1J+ FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN6 OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJC XCeMe4BO4iaxUQARAQABzRdtYXJrdXMucHJvYnN0QHBvc3Rlby5kZcLBkQQTAQgAOxYhBIJ0GMT0 rFjncjDEczR2H/jnrUPSBQJog714AhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEDR2 H/jnrUPSgdkQAISaTk2D345ehXEkn5z2yUEjaVjHIE7ziqRaOgn/QanCgeTUinIv6L6QXUFvvIfH 1OLPwQ1hfvEg9NnNLyFezWSy6jvoVBTIPqicD/r3FkithnQ1IDkdSjrarPMxJkvuh3l7XZHo49GV HQ8i5zh5w4YISrcEtE99lJisvni2Jqx7we5tey9voQFDyM8jxlSWv3pmoUTCtBkX/eKHJXosgsuS B4TGDCVPOjla/emI5c9MhMG7O4WEEmoSdPbmraPw66YZD6uLyhV4DPHbiDWRzXWnClHSyjB9rky9 lausFxogvu4l9H+KDsXIadNDWdLdu1/enS/wDd9zh5S78rY2jeXaG4mnf4seEKamZ7KQ6FIHrcyP ezdDzssPQcTQcGRMQzCn6wP3tlGk7rsfmyHMlFqdRoNNv+ZER/OkmZFPW655zRfbMi0vtrqK2Awm 9ggobb1oktfd9PPNXMUY+DNVlgR2G7jLnenSoQausLUm0pHoNE8TWFv851Y6SOYnvn488sP1Tki5 F3rKwclawQFHUXTCQw+QSh9ay8xgnNZfH+u9NY7w3gPoeKBOAFcBc2BtzcgekeWS8qgEmm2/oNFV G0ivPQbRx8FjRKbuF7g3YhgNZZ0ac8FneuUtJ2PkSIFTZhaAiC0utvxk0ndmWFiW4acEkMZGrLaM L2zWNjrqwsD2zsFNBGiDvXgBEADCXQy1n7wjRxG12DOVADawjghKcG+5LtEf31WftHKLFbp/HArj BhkT6mj+CCI1ClqY+FYU5CK/s0ScMfLxRGLZ0Ktzawb78vOgBVFT3yB1yWBTewsAXdqNqRooaUNo 8cG/NNJLjhccH/7PO/FWX5qftOVUJ/AIsAhKQJ18Tc8Ik73v427EDxuKb9mTAnYQFA3Ev3hAiVbO 6Rv39amVOfJ8sqwiSUGidj2Fctg2aB5JbeMln0KCUbTD1LhEFepeKypfofAXQbGwaCjAhmkWy/q3 IT1mUrPxOngbxdRoOx1tGUC0HCMUW1sFaJgQPMmDcR0JGPOpgsKnitsSnN7ShcCr1buel7vLnUMD +TAZ5opdoF6HjAvAnBQaijtK6minkrM0seNXnCg0KkV8xhMNa6zCs1rq4GgjNLJue2EmuyHooHA4 7JMoLVHcxVeuNTp6K2+XRx0Pk4e2Lj8IVy9yEYyrywEOC5XRW37KJjsiOAsumi1rkvM7QREWgUDe Xs0+RpxI3QrrANh71fLMRo7LKRF3Gvw13NVCCC9ea20P4PwhgWKStkwO2NO+YJsAoS1QycMi/vKu 0EHhknYXamaSV50oZzHKmX56vEeJHTcngrM8R1SwJCYopCx9gkz90bTVYlitJa5hloWTYeMD7FNj Y6jfVSzgM/K4gMgUNDW/PPGeMwARAQABwsF2BBgBCAAgFiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IF AmiDvXgCGwwACgkQNHYf+OetQ9LHDBAAhk+ab8+WrbS/b1/gYW3q1KDiXU719nCtfkUVXKidW5Ec Idlr5HGt8ilLoxSWT2Zi368iHCXS0WenGgPwlv8ifvB7TOZiiTDZROZkXjEBmU4nYjJ7GymawpWv oQwjMsPuq6ysbzWtOZ7eILx7cI0FjQeJ/Q2baRJub0uAZNwBOxCkAS6lpk5Fntd2u8CWmDQo4SYp xeuQ+pwkp0yEP30RhN2BO2DXiBEGSZSYh+ioGbCHQPIV3iVj0h6lcCPOqopZqyeCfigeacBI0nvN jHWz/spzF3+4OS+3RJvoHtAQmProxyGib8iVsTxgZO3UUi4TSODeEt0i0kHSPY4sCciOyXfAyYoD DFqhRjOEwBBxhr+scU4C1T2AflozvDwq3VSONjrKJUkhd8+WsdXxMdPFgBQuiKKwUy11mz6KQfcR wmDehF3UaUoxa+YIhWPbKmycxuX/D8SvnqavzAeAL1OcRbEI/HsoroVlEFbBRNBZLJUlnTPs8ZcU 4+8rq5YX1GUrJL3jf6SAfSgO7UdkEET3PdcKFYtS+ruV1Cp5V0q4kCfI5jk25iiz8grM2wOzVSsc l1mEkhiEPH87HP0whhb544iioSnumd3HJKL7dzhRegsMizatupp8D65A2JziW0WKopa1iw9fti3A aBeNN4ijKZchBXHPgVx+YtWRHfcm4l8= OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt Content-Type: text/plain; charset="utf-8" Implement the `AsBusDevice` trait for converting a `Device` reference to a bus device reference for all bus devices. The `AsBusDevice` trait allows abstractions to provide the bus device in class device callbacks. It must not be used by drivers and is intended for bus and class device abstractions only. Signed-off-by: Markus Probst --- rust/kernel/auxiliary.rs | 7 +++++++ rust/kernel/device.rs | 33 +++++++++++++++++++++++++++++++++ rust/kernel/pci.rs | 7 +++++++ rust/kernel/platform.rs | 7 +++++++ rust/kernel/usb.rs | 6 ++++++ 5 files changed, 60 insertions(+) diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs index 7a3b0b9c418e..db52062a4355 100644 --- a/rust/kernel/auxiliary.rs +++ b/rust/kernel/auxiliary.rs @@ -15,6 +15,7 @@ }; use core::{ marker::PhantomData, + mem::offset_of, ptr::{addr_of_mut, NonNull}, }; =20 @@ -233,6 +234,12 @@ extern "C" fn release(dev: *mut bindings::device) { } } =20 +// SAFETY: `auxiliary::Device` is a transparent wrapper of `struct auxilia= ry_device`. +// The offset is guaranteed to point to a valid device field inside `auxil= iary::Device`. +unsafe impl device::AsBusDevice for Devic= e { + const OFFSET: usize =3D offset_of!(bindings::auxiliary_device, dev); +} + // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend= on `Device`'s generic // argument. kernel::impl_device_context_deref!(unsafe { Device }); diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index a849b7dde2fd..bf09fd0b0199 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -511,6 +511,39 @@ impl DeviceContext for Core {} impl DeviceContext for CoreInternal {} impl DeviceContext for Normal {} =20 +/// Convert device references to bus device references. +/// +/// Bus devices can implement this trait to allow abstractions to provide = the bus device in +/// class device callbacks. +/// +/// This must not be used by drivers and is intended for bus and class dev= ice abstractions only. +/// +/// # Safety +/// +/// `AsBusDevice::OFFSET` must be the offset of the embedded base `struct = device` field within a +/// bus device structure. +pub(crate) unsafe trait AsBusDevice: AsRef= > { + /// The relative offset to the device field. + /// + /// Use `offset_of!(bindings, field)` macro to avoid breakage. + const OFFSET: usize; + + /// Convert a reference to [`Device`] into `Self`. + /// + /// # Safety + /// + /// `dev` must be contained in `Self`. + unsafe fn from_device(dev: &Device) -> &Self + where + Self: Sized, + { + let raw =3D dev.as_raw(); + // SAFETY: `raw - Self::OFFSET` is guaranteed by the safety requir= ements + // to be a valid pointer to `Self`. + unsafe { &*raw.byte_sub(Self::OFFSET).cast::() } + } +} + /// # Safety /// /// The type given as `$device` must be a transparent wrapper of a type th= at doesn't depend on the diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs index 7fcc5f6022c1..d78f6feeaae9 100644 --- a/rust/kernel/pci.rs +++ b/rust/kernel/pci.rs @@ -19,6 +19,7 @@ }; use core::{ marker::PhantomData, + mem::offset_of, ops::Deref, ptr::{addr_of_mut, NonNull}, }; @@ -593,6 +594,12 @@ pub fn set_master(&self) { } } =20 +// SAFETY: `pci::Device` is a transparent wrapper of `struct pci_dev`. +// The offset is guaranteed to point to a valid device field inside `pci::= Device`. +unsafe impl device::AsBusDevice for Devic= e { + const OFFSET: usize =3D offset_of!(bindings::pci_dev, dev); +} + // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend= on `Device`'s generic // argument. kernel::impl_device_context_deref!(unsafe { Device }); diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs index 7205fe3416d3..7197264b5a53 100644 --- a/rust/kernel/platform.rs +++ b/rust/kernel/platform.rs @@ -19,6 +19,7 @@ =20 use core::{ marker::PhantomData, + mem::offset_of, ptr::{addr_of_mut, NonNull}, }; =20 @@ -285,6 +286,12 @@ pub fn io_request_by_name(&self, name: &CStr) -> Optio= n> { } } =20 +// SAFETY: `platform::Device` is a transparent wrapper of `struct platform= _device`. +// The offset is guaranteed to point to a valid device field inside `platf= orm::Device`. +unsafe impl device::AsBusDevice for Devic= e { + const OFFSET: usize =3D offset_of!(bindings::platform_device, dev); +} + macro_rules! define_irq_accessor_by_index { ( $(#[$meta:meta])* $fn_name:ident, diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs index 14ddb711bab3..ec21261baf6a 100644 --- a/rust/kernel/usb.rs +++ b/rust/kernel/usb.rs @@ -324,6 +324,12 @@ fn as_raw(&self) -> *mut bindings::usb_interface { } } =20 +// SAFETY: `usb::Interface` is a transparent wrapper of `struct usb_interf= ace`. +// The offset is guaranteed to point to a valid device field inside `usb::= Interface`. +unsafe impl device::AsBusDevice for Inter= face { + const OFFSET: usize =3D offset_of!(bindings::usb_interface, dev); +} + // SAFETY: `Interface` is a transparent wrapper of a type that doesn't dep= end on // `Interface`'s generic argument. kernel::impl_device_context_deref!(unsafe { Interface }); --=20 2.51.0 From nobody Sun Feb 8 01:31:21 2026 Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) (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 199BE321F48 for ; Mon, 27 Oct 2025 20:06:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.66 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761595575; cv=none; b=Jt8A6sGPnx6tXpbKXRZ8fFS8Ql9+M46SAntUDYVquLnr/pWqCXqgXLOGmbv9GNQ4HA3AtW+laFwWJN0y3VkXpblJvhSQhd0QrJPnN5Mbs49/TsiVqIQFeh/zKdWw7JaPHSpACOYiVNhqE1oTk4e4aFY0Ix/Ab9KbwDnKBT5seJw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761595575; c=relaxed/simple; bh=9h+tAmuuvK9EqxjAQukL4RGSRcJTnFax99ceow6JrNs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Aul9ov56XYiuY1BsnxLKnVTlmYNU2uxg/wawtamY5XaCRGm+38DrtE09IXDKZA1+zElWMcWoQg1d0V4nSwGacPu4HK48+SZDeRU7/FmOTxGhWsDRoDcnH7mygtnA8Bvu7j8ru+sK6o5wzDB6oRl19XgG/HXOFbIvCQrKvJbluD8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=lihQ/4hw; arc=none smtp.client-ip=185.67.36.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="lihQ/4hw" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id D8231240104 for ; Mon, 27 Oct 2025 21:06:06 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1761595566; bh=h0DeGFcALHELGR30GG6cngIwx4x0xFLg1HmmpECNVtg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:Autocrypt:OpenPGP:From; b=lihQ/4hwiGoQCnAqG8TOzrT9l3J8DBnimtX8K5YL4WObXt3xkpUbWT2igtTgFpfKG 3nMobslxZESDVc9v6luPAFeOcuBVSYQ7iVrblHZJpBtnwPnVbF2g3aRL036zg7MGvd /wMqEs4x8OonARL4CwbYw/+KRRSmtIXK2+c/NMs3jkvXfVU6uOMPgQrpDLCTodP52s PjZpCALCMw21iUTS9uqZO/4oUQfMSX5/pvfgwYCeMoRlv2N1saDbvqIrLZRL6jiW9n wf4DdPsT1sICApy2w+V2gDCxEAzofOCo7Js2OK2RjcV56k3xByu3/deTT+uZ6tReE/ dAGH3RaMpRQyA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4cwPdl44jTz9rxP; Mon, 27 Oct 2025 21:06:03 +0100 (CET) From: Markus Probst To: Greg Kroah-Hartman , Miguel Ojeda , Alex Gaynor , Danilo Krummrich , "Rafael J. Wysocki" , Lee Jones , Pavel Machek Cc: Dave Ertman , Ira Weiny , Leon Romanovsky , Boqun Feng , Gary Guo , bjorn3_gh@protonmail.com, Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Bjorn Helgaas , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Markus Probst , rust-for-linux@vger.kernel.org, linux-leds@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 2/2] rust: leds: add basic led classdev abstractions Date: Mon, 27 Oct 2025 20:06:05 +0000 Message-ID: <20251027200547.1038967-3-markus.probst@posteo.de> In-Reply-To: <20251027200547.1038967-1-markus.probst@posteo.de> References: <20251027200547.1038967-1-markus.probst@posteo.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=15201; i=markus.probst@posteo.de; h=from:subject; bh=9h+tAmuuvK9EqxjAQukL4RGSRcJTnFax99ceow6JrNs=; b=owEBbQKS/ZANAwAIATR2H/jnrUPSAcsmYgBo/9B9WaSu8UMraopNwFIpQc/riJ7x5H6IvI+LC 6jkNiSXOvuJAjMEAAEIAB0WIQSCdBjE9KxY53IwxHM0dh/4561D0gUCaP/QfQAKCRA0dh/4561D 0tiyD/9rScnURLIZIg2OImphI6EhXGq8DOtRIgVgBjJ4kHsw0IFWs0KQp8Kvj2joein/ttXUobM cJ0OdmKXkxifzWDjdTCWN/mpzyGrJIurtUoz7xs3ry/fdaUCwII0vJg4/XgkPrTZUH93ZEv3Y3D gc5Vir7ddchlYiq9QnRJrWGFL7Em5LvKj2wm3n7WeRRNvvAyZNYBcl3U17IxU+QqhN7cXSQhd9o gSn33BS/bhN5HsytKDNs6qKx2nw7vBRGGnsf8N9npmynzloBvBbRA7N1RFabWMMoNxWkXAPt7K1 YHsJ/UcmEvF+94ViN3FdkbwT2QatJfbcIR4Bk7Kt1+KVU5BNBU3pNSY0pw20mZMFjwTrFpKf/sz EHPYnMA8hF7xN38f3gervNGrCsvIJWOYzBCZtfX/TkpLAq9Ac/6lrs38HpruTrEh83JT+wA6ceU +yNKCDA2e3LagW3gJZjbz+GaWlWqmDoi91e+eWdZTvK/WQLtWn4ob75Nw55zkyZk6nO4MX3zR/G M/Y7gGbyxHKf+abfcMLv1vS3myNNzTnnLsZNAWO4zk0tNrkpZ9QueeuadunR9KxtqdKO8RgYM28 QxdSHQB72CPgmGD39NRAC+JMPONTzlEzaa0p1v7pQsw9fzIC0B5rOxOeyUaIdIc0c7rnsW3fiVB kKLc/L2+1dq4vUg == X-Developer-Key: i=markus.probst@posteo.de; a=openpgp; fpr=827418C4F4AC58E77230C47334761FF8E7AD43D2 Content-Transfer-Encoding: quoted-printable Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=xsFNBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93qReNLkO WguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVAm76Ww+ /pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt9k5JA RhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbmfAja oT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwTjRQ xBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1J+ FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN6 OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJC XCeMe4BO4iaxUQARAQABzRdtYXJrdXMucHJvYnN0QHBvc3Rlby5kZcLBkQQTAQgAOxYhBIJ0GMT0 rFjncjDEczR2H/jnrUPSBQJog714AhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEDR2 H/jnrUPSgdkQAISaTk2D345ehXEkn5z2yUEjaVjHIE7ziqRaOgn/QanCgeTUinIv6L6QXUFvvIfH 1OLPwQ1hfvEg9NnNLyFezWSy6jvoVBTIPqicD/r3FkithnQ1IDkdSjrarPMxJkvuh3l7XZHo49GV HQ8i5zh5w4YISrcEtE99lJisvni2Jqx7we5tey9voQFDyM8jxlSWv3pmoUTCtBkX/eKHJXosgsuS B4TGDCVPOjla/emI5c9MhMG7O4WEEmoSdPbmraPw66YZD6uLyhV4DPHbiDWRzXWnClHSyjB9rky9 lausFxogvu4l9H+KDsXIadNDWdLdu1/enS/wDd9zh5S78rY2jeXaG4mnf4seEKamZ7KQ6FIHrcyP ezdDzssPQcTQcGRMQzCn6wP3tlGk7rsfmyHMlFqdRoNNv+ZER/OkmZFPW655zRfbMi0vtrqK2Awm 9ggobb1oktfd9PPNXMUY+DNVlgR2G7jLnenSoQausLUm0pHoNE8TWFv851Y6SOYnvn488sP1Tki5 F3rKwclawQFHUXTCQw+QSh9ay8xgnNZfH+u9NY7w3gPoeKBOAFcBc2BtzcgekeWS8qgEmm2/oNFV G0ivPQbRx8FjRKbuF7g3YhgNZZ0ac8FneuUtJ2PkSIFTZhaAiC0utvxk0ndmWFiW4acEkMZGrLaM L2zWNjrqwsD2zsFNBGiDvXgBEADCXQy1n7wjRxG12DOVADawjghKcG+5LtEf31WftHKLFbp/HArj BhkT6mj+CCI1ClqY+FYU5CK/s0ScMfLxRGLZ0Ktzawb78vOgBVFT3yB1yWBTewsAXdqNqRooaUNo 8cG/NNJLjhccH/7PO/FWX5qftOVUJ/AIsAhKQJ18Tc8Ik73v427EDxuKb9mTAnYQFA3Ev3hAiVbO 6Rv39amVOfJ8sqwiSUGidj2Fctg2aB5JbeMln0KCUbTD1LhEFepeKypfofAXQbGwaCjAhmkWy/q3 IT1mUrPxOngbxdRoOx1tGUC0HCMUW1sFaJgQPMmDcR0JGPOpgsKnitsSnN7ShcCr1buel7vLnUMD +TAZ5opdoF6HjAvAnBQaijtK6minkrM0seNXnCg0KkV8xhMNa6zCs1rq4GgjNLJue2EmuyHooHA4 7JMoLVHcxVeuNTp6K2+XRx0Pk4e2Lj8IVy9yEYyrywEOC5XRW37KJjsiOAsumi1rkvM7QREWgUDe Xs0+RpxI3QrrANh71fLMRo7LKRF3Gvw13NVCCC9ea20P4PwhgWKStkwO2NO+YJsAoS1QycMi/vKu 0EHhknYXamaSV50oZzHKmX56vEeJHTcngrM8R1SwJCYopCx9gkz90bTVYlitJa5hloWTYeMD7FNj Y6jfVSzgM/K4gMgUNDW/PPGeMwARAQABwsF2BBgBCAAgFiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IF AmiDvXgCGwwACgkQNHYf+OetQ9LHDBAAhk+ab8+WrbS/b1/gYW3q1KDiXU719nCtfkUVXKidW5Ec Idlr5HGt8ilLoxSWT2Zi368iHCXS0WenGgPwlv8ifvB7TOZiiTDZROZkXjEBmU4nYjJ7GymawpWv oQwjMsPuq6ysbzWtOZ7eILx7cI0FjQeJ/Q2baRJub0uAZNwBOxCkAS6lpk5Fntd2u8CWmDQo4SYp xeuQ+pwkp0yEP30RhN2BO2DXiBEGSZSYh+ioGbCHQPIV3iVj0h6lcCPOqopZqyeCfigeacBI0nvN jHWz/spzF3+4OS+3RJvoHtAQmProxyGib8iVsTxgZO3UUi4TSODeEt0i0kHSPY4sCciOyXfAyYoD DFqhRjOEwBBxhr+scU4C1T2AflozvDwq3VSONjrKJUkhd8+WsdXxMdPFgBQuiKKwUy11mz6KQfcR wmDehF3UaUoxa+YIhWPbKmycxuX/D8SvnqavzAeAL1OcRbEI/HsoroVlEFbBRNBZLJUlnTPs8ZcU 4+8rq5YX1GUrJL3jf6SAfSgO7UdkEET3PdcKFYtS+ruV1Cp5V0q4kCfI5jk25iiz8grM2wOzVSsc l1mEkhiEPH87HP0whhb544iioSnumd3HJKL7dzhRegsMizatupp8D65A2JziW0WKopa1iw9fti3A aBeNN4ijKZchBXHPgVx+YtWRHfcm4l8= OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt Content-Type: text/plain; charset="utf-8" Implement the core abstractions needed for led class devices, including: * `led::LedOps` - the trait for handling leds, including `brightness_set`, `brightness_get` and `blink_set` * `led::InitData` - data set for the led class device * `led::Device` - a safe wrapper around `led_classdev` Signed-off-by: Markus Probst --- rust/kernel/led.rs | 375 +++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 376 insertions(+) create mode 100644 rust/kernel/led.rs diff --git a/rust/kernel/led.rs b/rust/kernel/led.rs new file mode 100644 index 000000000000..1c1e23a0414c --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,375 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Abstractions for the leds driver model. +//! +//! C header: [`include/linux/leds.h`](srctree/include/linux/leds.h) + +use core::{marker::PhantomData, pin::Pin, ptr::NonNull}; + +use pin_init::{pin_data, pinned_drop, PinInit}; + +use crate::{ + build_error, container_of, + device::{self, property::FwNode, Bound, AsBusDevice}, + devres::Devres, + error::{from_result, to_result, Error, Result, VTABLE_DEFAULT_ERROR}, + macros::vtable, + str::CStr, + try_pin_init, + types::{ARef, Opaque}, +}; + +/// The led class device representation. +/// +/// This structure represents the Rust abstraction for a C `struct led_cla= ssdev`. +#[pin_data(PinnedDrop)] +pub struct Device { + ops: T, + #[pin] + classdev: Opaque, +} + +/// The led init data representation. +/// +/// This structure represents the Rust abstraction for a C `struct led_ini= t_data`. +#[derive(Default)] +pub struct InitData<'a> { + fwnode: Option<&'a FwNode>, + default_label: Option<&'a CStr>, + devicename: Option<&'a CStr>, + devname_mandatory: bool, +} + +impl InitData<'static> { + /// Creates a new [`InitData`] + pub fn new() -> Self { + Self::default() + } +} + +impl<'a> InitData<'a> { + /// Sets the firmware node + pub fn fwnode<'b, 'c>(self, fwnode: &'b FwNode) -> InitData<'c> + where + 'a: 'c, + 'b: 'c, + { + InitData { + fwnode: Some(fwnode), + ..self + } + } + + /// Sets a default label + pub fn default_label<'b, 'c>(self, label: &'b CStr) -> InitData<'c> + where + 'a: 'c, + 'b: 'c, + { + InitData { + default_label: Some(label), + ..self + } + } + + /// Sets the device name + pub fn devicename<'b, 'c>(self, devicename: &'b CStr) -> InitData<'c> + where + 'a: 'c, + 'b: 'c, + { + InitData { + devicename: Some(devicename), + ..self + } + } + + /// Sets if a device name is mandatory + pub fn devicename_mandatory(self, mandatory: bool) -> Self { + Self { + devname_mandatory: mandatory, + + ..self + } + } +} + +/// Trait defining the operations for a LED driver. +/// +/// # Examples +/// +///``` +/// # use kernel::{ +/// # c_str, device, devres::Devres, +/// # error::Result, led, +/// # macros::vtable, platform, prelude::*, +/// # }; +/// # use core::pin::Pin; +/// +/// struct MyLedOps; +/// +/// +/// #[vtable] +/// impl led::LedOps for MyLedOps { +/// type Bus =3D platform::Device; +/// const BLOCKING: bool =3D false; +/// const MAX_BRIGHTNESS: u32 =3D 255; +/// +/// fn brightness_set( +/// &self, +/// _dev: &platform::Device, +/// _brightness: u32 +/// ) -> Result<()> { +/// // Set the brightness for the led here +/// Ok(()) +/// } +/// } +/// +/// fn register_my_led( +/// parent: &platform::Device, +/// ) -> Result>>>> { +/// KBox::pin_init(led::Device::new( +/// parent, +/// led::InitData::new() +/// .default_label(c_str!("my_led")), +/// MyLedOps, +/// ), GFP_KERNEL) +/// } +///``` +/// Led drivers must implement this trait in order to register and handle = a [`Device`]. +#[vtable] +pub trait LedOps: Send + 'static + Sized { + /// The bus device required by the implementation. + #[allow(private_bounds)] + type Bus: AsBusDevice; + /// If set true, [`LedOps::brightness_set`] and [`LedOps::blink_set`] = must perform the + /// operation immediately. If set false, they must not sleep. + const BLOCKING: bool; + /// The max brightness level + const MAX_BRIGHTNESS: u32; + + /// Sets the brightness level. + /// + /// See also [`LedOps::BLOCKING`] + fn brightness_set(&self, dev: &Self::Bus, brightness: u32) -> Result<(= )>; + + /// Gets the current brightness level. + fn brightness_get(&self, _dev: &Self::Bus) -> u32 { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Activates hardware accelerated blinking. + /// + /// delays are in milliseconds. If both are zero, a sensible default s= hould be chosen. + /// The caller should adjust the timings in that case and if it can't = match the values + /// specified exactly. Setting the brightness to 0 will disable the ha= rdware accelerated + /// blinking. + /// + /// See also [`LedOps::BLOCKING`] + fn blink_set( + &self, + _dev: &Self::Bus, + _delay_on: &mut usize, + _delay_off: &mut usize, + ) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } +} + +// SAFETY: A `led::Device` can be unregistered from any thread. +unsafe impl Send for Device {} + +// SAFETY: `led::Device` can be shared among threads because all methods o= f `led::Device` +// are thread safe. +unsafe impl Sync for Device {} + +impl Device { + /// Registers a new led classdev. + /// + /// The [`Device`] will be unregistered on drop. + pub fn new<'a>( + parent: &'a T::Bus, + init_data: InitData<'a>, + ops: T, + ) -> impl PinInit, Error> + 'a { + Devres::new( + parent.as_ref(), + try_pin_init!(Self { + ops, + classdev <- Opaque::try_ffi_init(|ptr: *mut bindings::led_= classdev| { + // SAFETY: `try_ffi_init` guarantees that `ptr` is val= id for write. + // `led_classdev` gets fully initialized in-place by + // `led_classdev_register_ext` including `mutex` and `= list_head`. + unsafe { + ptr.write(bindings::led_classdev { + max_brightness: T::MAX_BRIGHTNESS, + brightness_set: (!T::BLOCKING) + .then_some(Adapter::::brightness_set_ca= llback), + brightness_set_blocking: T::BLOCKING + .then_some(Adapter::::brightness_set_bl= ocking_callback), + brightness_get: T::HAS_BRIGHTNESS_GET + .then_some(Adapter::::brightness_get_ca= llback), + blink_set: T::HAS_BLINK_SET.then_some(Adapter:= :::blink_set_callback), + ..bindings::led_classdev::default() + }) + }; + + let fwnode =3D init_data.fwnode.map(ARef::from); + + let mut init_data =3D bindings::led_init_data { + fwnode: fwnode + .as_ref() + .map_or(core::ptr::null_mut(), |fwnode| fwnode= .as_raw()), + default_label: init_data + .default_label + .map_or(core::ptr::null(), CStr::as_char_ptr), + devicename: init_data + .devicename + .map_or(core::ptr::null(), CStr::as_char_ptr), + devname_mandatory: init_data.devname_mandatory, + }; + + // SAFETY: + // - `parent.as_raw()` is guaranteed to be a pointer t= o a valid `device` + // or a null pointer. + // - `ptr` is guaranteed to be a pointer to an initial= ized `led_classdev`. + to_result(unsafe { + bindings::led_classdev_register_ext( + parent.as_ref().as_raw(), + ptr, + &mut init_data, + ) + })?; + + core::mem::forget(fwnode); // keep the reference count= incremented + + Ok::<_, Error>(()) + }), + }), + ) + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded wi= thin a + /// `led::Device`. + unsafe fn from_raw<'a>(led_cdev: *mut bindings::led_classdev) -> &'a S= elf { + // SAFETY: The function's contract guarantees that `led_cdev` poin= ts to a `led_classdev` + // field embedded within a valid `led::Device`. `container_of!` ca= n therefore + // safely calculate the address of the containing struct. + unsafe { &*container_of!(Opaque::cast_from(led_cdev), Self, classd= ev) } + } + + fn parent(&self) -> &device::Device { + // SAFETY: + // - `self.classdev.get()` is guaranteed to be a valid pointer to = `led_classdev`. + unsafe { device::Device::from_raw((*(*self.classdev.get()).dev).pa= rent) } + } +} + +struct Adapter { + _p: PhantomData, +} + +impl Adapter { + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded wi= thin a + /// `led::Device`. + /// This function is called on setting the brightness of a led. + unsafe extern "C" fn brightness_set_callback( + led_cdev: *mut bindings::led_classdev, + brightness: u32, + ) { + // SAFETY: The function's contract guarantees that `led_cdev` is a= valid pointer to a + // `led_classdev` embedded within a `led::Device`. + let classdev =3D unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T= ::Bus`. + let parent =3D unsafe { T::Bus::from_device(classdev.parent()) }; + + let _ =3D classdev.ops.brightness_set(parent, brightness); + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded wi= thin a + /// `led::Device`. + /// This function is called on setting the brightness of a led immedia= tely. + unsafe extern "C" fn brightness_set_blocking_callback( + led_cdev: *mut bindings::led_classdev, + brightness: u32, + ) -> i32 { + from_result(|| { + // SAFETY: The function's contract guarantees that `led_cdev` = is a valid pointer to a + // `led_classdev` embedded within a `led::Device`. + let classdev =3D unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained i= n `T::Bus`. + let parent =3D unsafe { T::Bus::from_device(classdev.parent())= }; + + classdev.ops.brightness_set(parent, brightness)?; + Ok(0) + }) + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded wi= thin a + /// `led::Device`. + /// This function is called on getting the brightness of a led. + unsafe extern "C" fn brightness_get_callback(led_cdev: *mut bindings::= led_classdev) -> u32 { + // SAFETY: The function's contract guarantees that `led_cdev` is a= valid pointer to a + // `led_classdev` embedded within a `led::Device`. + let classdev =3D unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T= ::Bus`. + let parent =3D unsafe { T::Bus::from_device(classdev.parent()) }; + + classdev.ops.brightness_get(parent) + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded wi= thin a + /// `led::Device`. + /// `delay_on` and `delay_off` must be valid pointers to `usize` and h= ave + /// exclusive access for the period of this function. + /// This function is called on enabling hardware accelerated blinking. + unsafe extern "C" fn blink_set_callback( + led_cdev: *mut bindings::led_classdev, + delay_on: *mut usize, + delay_off: *mut usize, + ) -> i32 { + from_result(|| { + // SAFETY: The function's contract guarantees that `led_cdev` = is a valid pointer to a + // `led_classdev` embedded within a `led::Device`. + let classdev =3D unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained i= n `T::Bus`. + let parent =3D unsafe { T::Bus::from_device(classdev.parent())= }; + + classdev.ops.blink_set( + parent, + // SAFETY: The function's contract guarantees that `delay_= on` points to a `usize` + // and is exclusive for the period of this function. + unsafe { &mut *delay_on }, + // SAFETY: The function's contract guarantees that `delay_= off` points to a `usize` + // and is exclusive for the period of this function. + unsafe { &mut *delay_off }, + )?; + Ok(0) + }) + } +} + +#[pinned_drop] +impl PinnedDrop for Device { + fn drop(self: Pin<&mut Self>) { + let raw =3D self.classdev.get(); + // SAFETY: The existence of `self` guarantees that `self.classdev.= get()` is a pointer to a + // valid `struct led_classdev`. + let dev: &device::Device =3D unsafe { device::Device::from_raw((*r= aw).dev) }; + + let _fwnode =3D dev + .fwnode() + // SAFETY: the reference count of `fwnode` has previously been + // incremented in `led::Device::new`. + .map(|fwnode| unsafe { ARef::from_raw(NonNull::from(fwnode)) }= ); + + // SAFETY: The existence of `self` guarantees that `self.classdev`= has previously been + // successfully registered with `led_classdev_register_ext`. + unsafe { bindings::led_classdev_unregister(self.classdev.get()) }; + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 3dd7bebe7888..c03b7b242a2b 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -103,6 +103,7 @@ pub mod jump_label; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod led; pub mod list; pub mod maple_tree; pub mod miscdevice; --=20 2.51.0