From mboxrd@z Thu Jan 1 00:00:00 1970 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 6C5233043AD for ; Sat, 15 Nov 2025 17:26:04 +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=1763227567; cv=none; b=eIOam2P+jIeWJStDTd7gNfqbF+DOO8XkvTwo13LN4Jt/eTRpwx7iA3DDlBb9ObkXsLY86BejUYRx9tsYsah5uFiuX9PI4SuroOueMsx1d0FshgcZBOs1ffbqEo+xU8ZW7IKeMQv+tjVqnuc2wIzb++Ao8KWpZ6RLXG1ioeFVHxs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763227567; c=relaxed/simple; bh=t68H8rXu6XmkMh+iLw+R6lOjuYBvGB8PMDn92zVlKYk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=rYqB43ZPqLUfHOcufIGcGUDDCwBaaiFg5D4BcfnqNT6U0xCw6dWb52VJ1/cRfW6YdKuF0lDw+etn0CKq54WOp585t4TtChUGZNbMy77liGt5jVil/mCb7JgBkMjkMYyIQU2T/N+UQce38aUD9zCs5Rqw21FroNrtEw5ZDI8w1A0= 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=o5FNgKOc; 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="o5FNgKOc" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id EA8A3240105 for ; Sat, 15 Nov 2025 18:26:00 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1763227560; bh=4QYoNPwoYQKT22elmcFf1tXNwc4vKowEFwTDurGb5Jc=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=o5FNgKOcECtgoQLWpgHmyDu9Nv8iUmGRYVPY5qcgKRbptfMnPNN3SQUmbHen5RViH dL3HIbFTDUB935N7XGhnODoVc84skDXJMDcmaOyG7VqGEpOStDmfS1U1y8l4ui9Fsb ap1vTRyvVBuicK4WhWZrNBLBN9WfSfT3cAg/y9v8HuDibO56gscQ7VPD0XCphZKOch kQm5tBsQp6NA1LmsM5CfXoIq3yXOMxbM46MacIhOlkX9dpDInKi7+HFUAHzXCP68X4 f2F8G3MbbAg4DGZWgpvoM234x48gMjUD6DC/0zRZkpscxPdge/1dsS6ckZX+xzUUhg FIQwYlyn+DPhQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4d81BF3Y3bz9rxN; Sat, 15 Nov 2025 18:25:57 +0100 (CET) From: Markus Probst Date: Sat, 15 Nov 2025 17:25:59 +0000 Subject: [PATCH v8 1/4] rust: Add trait to convert a device reference to a bus device reference Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251115-rust_leds-v8-1-d9a41f355538@posteo.de> References: <20251115-rust_leds-v8-0-d9a41f355538@posteo.de> In-Reply-To: <20251115-rust_leds-v8-0-d9a41f355538@posteo.de> To: Lee Jones , Pavel Machek , Greg Kroah-Hartman , Dave Ertman , Ira Weiny , Leon Romanovsky , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , "Rafael J. Wysocki" , Bjorn Helgaas , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= Cc: rust-for-linux@vger.kernel.org, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Markus Probst X-Developer-Signature: v=1; a=openpgp-sha256; l=5575; i=markus.probst@posteo.de; h=from:subject:message-id; bh=t68H8rXu6XmkMh+iLw+R6lOjuYBvGB8PMDn92zVlKYk=; b=kA0DAAgBNHYf+OetQ9IByyZiAGkYt6KgKX/PeBpr9apcWnZAiYnycFTjkPh2p6FjafjF1csrr okCMwQAAQgAHRYhBIJ0GMT0rFjncjDEczR2H/jnrUPSBQJpGLeiAAoJEDR2H/jnrUPSyQwP/2we dxICIPBqDGQomYu6VqQb9I3KtmDWRKlHsAWkzp1avm8yuaY1VuFsNYIvs+ctHKeFXQ+Ab02H9PW nvjjCnJ50f+OAi5tkh5EvcM5EFCiQiLakKE3/heCEmcshkzS5QFvix3k+bYWlWDFZxufyjd3VEO VE9v+mnpIPbO9/2Ryqg2R5/Sldy4NqsECwsVPpHejOW29I6TPg5zHPohJZdClbxUFZOTpvFWxNA WFW48HtSbDg1YGAQGZ49VYE7kN+g7Eyd/nQ+eiyepJ6dK//BAn3ZJfnNDCn7yzuZt/oh+EDBmlI CHGPY/4iURwFGuJV4uIyVqt7n09i3G8c1VfUbnli0/hDw7lzTsPuYtUTPCNeXv9insiTm8y8r1s MzHW3jmpsBcpRYQRg7YIj/IaIFK6cKJvJD8FGaWju+AbL6BnHUmexD84riOUD8u1mRkbr1ciE7h vJbdtoro6J8KzLtSZ3Bffg7JWuDb7UDWNFpEgHU6NThS1a02YyfhQvx0al6KQpihtiq/R7UOFvM +inmn2WG8GVgjJWneAZP+QD0nS03V+G5+5Zw92yiQXJAZA6DjZ465xeRsiAv97SpvZiB0wEHZ/n eh0mJi8lqq5l12iw8p1GMFiQfhrjdJfz07sjWN178hTrcTUvtDyIVD5Z9EmPqQ2KRjn31SAW4s2 +O7Ir X-Developer-Key: i=markus.probst@posteo.de; a=openpgp; fpr=827418C4F4AC58E77230C47334761FF8E7AD43D2 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 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}, }; @@ -233,6 +234,12 @@ extern "C" fn release(dev: *mut bindings::device) { } } +// SAFETY: `auxiliary::Device` is a transparent wrapper of `struct auxiliary_device`. +// The offset is guaranteed to point to a valid device field inside `auxiliary::Device`. +unsafe impl device::AsBusDevice for Device { + const OFFSET: usize = 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 {} +/// 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 device 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 = dev.as_raw(); + // SAFETY: `raw - Self::OFFSET` is guaranteed by the safety requirements + // 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 that 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) { } } +// 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 Device { + const OFFSET: usize = 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 @@ use core::{ marker::PhantomData, + mem::offset_of, ptr::{addr_of_mut, NonNull}, }; @@ -285,6 +286,12 @@ pub fn io_request_by_name(&self, name: &CStr) -> Option> { } } +// SAFETY: `platform::Device` is a transparent wrapper of `struct platform_device`. +// The offset is guaranteed to point to a valid device field inside `platform::Device`. +unsafe impl device::AsBusDevice for Device { + const OFFSET: usize = 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 { } } +// SAFETY: `usb::Interface` is a transparent wrapper of `struct usb_interface`. +// The offset is guaranteed to point to a valid device field inside `usb::Interface`. +unsafe impl device::AsBusDevice for Interface { + const OFFSET: usize = offset_of!(bindings::usb_interface, dev); +} + // SAFETY: `Interface` is a transparent wrapper of a type that doesn't depend on // `Interface`'s generic argument. kernel::impl_device_context_deref!(unsafe { Interface }); -- 2.51.0