From nobody Fri Dec 19 12:16:03 2025 Received: from mout01.posteo.de (mout01.posteo.de [185.67.36.65]) (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 9E9E9239E9E for ; Thu, 9 Oct 2025 17:07:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.65 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760029681; cv=none; b=iyRlG/m+pt0Nql44KAL9VGv5zRDv2f5z9t3ZCc6JmdVqnkLyauiEcHwo9GgvFGT0swVL+Q6NwIpPNz3n7yVKbUOa1tJHK5sxsSTyb7+yXHHwhqZW3kxN7jmK4lemwzMUmzeyyI/09uKqX8gNSFS/vh76nNRLL4cq5d/Wzr6ymaQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760029681; c=relaxed/simple; bh=HsJlFXmTtn+6F53p9248bYCRpbQn4cG6ElphdF2A5I0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pyPJ4Ht8EI919+3KuURrBC+DUdUZapMekGFJp/1gJPBHL9ksaZdLaINi9kzTrFHgHIymYM32h0hY309yoY5jqYTWEvkImvo2ZuDeG5Lrj1/92icjRn5MoSkgW8QcvefjUm0m0YclOFg5/uKtPFb8PwDYhQU68L3ZuqzcGEXIFJQ= 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=FLuQZGt3; arc=none smtp.client-ip=185.67.36.65 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="FLuQZGt3" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 2120A24002B for ; Thu, 9 Oct 2025 19:07:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1760029678; bh=GoMIaR/jMyBEUfeUogX618tSLBnZpki3PRU9UIDR6aE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:Autocrypt:OpenPGP:From; b=FLuQZGt3B/IdS2FLZa/wyoZdg/Vp9X9SAbLytkCxxvVdNkkVwHXop9VG+zsNCv4En m/l86IDon9oz9wo+ieZFIeeiRgKC8dXgtapYySBKDQ2gv+shgg81/xvm0PRMJCDRJG k8U7rKBbBQReUJiNjoJrV5g0zUdyHRLwHmD8TbK5Ixfd413f6TQsTvyCYOMwrcJlpv oXimcsgcK7Jg92f6S0HbReBrwHZBtGeBsw7Pb5XggyKHFxFzobBW082yzE4DcES0kY 9IpQbm88R0TEyAuo+QQU0bhsdpu8KprZkghxxoZg8CzrbfzgcaVFV/gOBytdbunuS4 QZfxaCUf0EtuQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4cjGXX1x0Vz9rwn; Thu, 9 Oct 2025 19:07:56 +0200 (CEST) From: Markus Probst To: Danilo Krummrich , Miguel Ojeda , Alex Gaynor , Lee Jones , Pavel Machek Cc: Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Uladzislau Rezki , Boqun Feng , Gary Guo , bjorn3_gh@protonmail.com, Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Markus Probst , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org Subject: [PATCH 2/2] rust: leds: add basic led classdev abstractions Date: Thu, 09 Oct 2025 17:07:57 +0000 Message-ID: <20251009170739.235221-3-markus.probst@posteo.de> In-Reply-To: <20251009170739.235221-1-markus.probst@posteo.de> References: <20251009170739.235221-1-markus.probst@posteo.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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::Handler` - the trait for handling leds, including `brightness_set` * `led::InitData` - data set for the led class device * `led::Device` - a safe wrapper arround `led_classdev` Signed-off-by: Markus Probst --- rust/kernel/led.rs | 296 +++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 297 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..2fddc6088e09 --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,296 @@ +// 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::pin::Pin; + +use pin_init::{pin_data, pinned_drop, PinInit}; + +use crate::{ + alloc::KBox, + container_of, + device::{self, property::FwNode}, + error::{code::EINVAL, from_result, to_result, Error, Result}, + prelude::GFP_KERNEL, + str::CStr, + try_pin_init, + types::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 { + handler: KBox, + #[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 [`LedInitData`] + 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 + } + } +} + +/// The led handler trait. +/// +/// # Examples +/// +///``` +/// # use kernel::{c_str, led, alloc::KBox, error::{Result, code::ENOSYS}}; +/// # use core::pin::Pin; +/// +/// struct MyHandler; +/// +/// +/// impl led::Handler for MyHandler { +/// const BLOCKING =3D false; +/// const MAX_BRIGHTNESS =3D 255; +/// +/// fn brightness_set(&self, _brightness: u32) -> Result<()> { +/// // Set the brightness for the led here +/// Ok(()) +/// } +/// } +/// +/// fn register_my_led() -> Result>> { +/// let handler =3D MyHandler; +/// KBox::pin_init(led::Device::new( +/// None, +/// None, +/// led::InitData::new() +/// .default_label(c_str!("my_led")), +/// handler, +/// )) +/// } +///``` +/// Led drivers must implement this trait in order to register and handle = a [`Device`]. +pub trait Handler { + /// If set true, [`Handler::brightness_set`] and [`Handler::blink_set`= ] must not sleep + /// and perform the operation immediately. + const BLOCKING: bool; + /// Set this to true, if [`Handler::blink_set`] is implemented. + const BLINK: bool =3D false; + /// The max brightness level + const MAX_BRIGHTNESS: u32; + + /// Sets the brightness level + /// + /// See also [`Handler::BLOCKING`] + fn brightness_set(&self, brightness: u32) -> Result<()>; + + /// 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 [`Handler::BLOCKING`] + fn blink_set(&self, _delay_on: &mut usize, _delay_off: &mut usize) -> = Result<()> { + Err(EINVAL) + } +} + +trait HandlerImpl { + fn brightness_set(&self, brightness: u32) -> Result<()>; + fn blink_set(&self, delay_on: &mut usize, delay_off: &mut usize) -> Re= sult<()>; +} + +impl HandlerImpl for T { + fn brightness_set(&self, brightness: u32) -> Result<()> { + T::brightness_set(self, brightness) + } + + fn blink_set(&self, delay_on: &mut usize, delay_off: &mut usize) -> Re= sult<()> { + T::blink_set(self, delay_on, delay_off) + } +} + +// 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 and drop. + pub fn new<'a, T: Handler + 'static>( + parent: Option<&'a device::Device>, + init_data: InitData<'a>, + handler: T, + ) -> impl PinInit + use<'a, T> { + try_pin_init!(Self { + handler <- { + let handler: KBox =3D KBox::::new(hand= ler, GFP_KERNEL)?; + Ok::<_, Error>(handler) + }, + classdev <- Opaque::try_ffi_init(|ptr: *mut bindings::led_clas= sdev| { + // SAFETY: `try_ffi_init` guarantees that `ptr` is valid f= or write. + unsafe { ptr.write(bindings::led_classdev { + max_brightness: T::MAX_BRIGHTNESS, + brightness_set: T::BLOCKING.then_some( + brightness_set as unsafe extern "C" fn(*mut bindin= gs::led_classdev, u32) + ), + brightness_set_blocking: (!T::BLOCKING).then_some( + brightness_set_blocking + as unsafe extern "C" fn(*mut bindings::led_cla= ssdev,u32) -> i32 + ), + blink_set: T::BLINK.then_some( + blink_set + as unsafe extern "C" fn(*mut bindings::led_cla= ssdev, *mut usize, + *mut usize) -> i32 + ), + .. bindings::led_classdev::default() + }) }; + + let mut init_data =3D bindings::led_init_data { + fwnode: init_data.fwnode.map_or(core::ptr::null_mut(),= FwNode::as_raw), + default_label: init_data.default_label + .map_or(core::ptr::null(), CSt= r::as_char_ptr), + devicename: init_data.devicename.map_or(core::ptr::nul= l(), CStr::as_char_ptr), + devname_mandatory: init_data.devname_mandatory, + }; + + let parent =3D parent + .map_or(core::ptr::null_mut(), device::Device::as_raw); + + // SAFETY: + // - `parent` is guaranteed to be a pointer to a valid `de= vice` + // or a null pointer. + // - `ptr` is guaranteed to be a pointer to an initialized= `led_classdev`. + to_result(unsafe { + bindings::led_classdev_register_ext(parent, ptr, &mut = init_data) + }) + }), + }) + } +} + +extern "C" fn brightness_set(led_cdev: *mut bindings::led_classdev, bright= ness: u32) { + // SAFETY: `led_cdev` is a valid pointer to a `led_classdev` stored in= side a `Device`. + let classdev =3D unsafe { + &*container_of!( + led_cdev.cast::>(), + Device, + classdev + ) + }; + let _ =3D classdev.handler.brightness_set(brightness); +} + +extern "C" fn brightness_set_blocking( + led_cdev: *mut bindings::led_classdev, + brightness: u32, +) -> i32 { + // SAFETY: `led_cdev` is a valid pointer to a `led_classdev` stored in= side a `Device`. + let classdev =3D unsafe { + &*container_of!( + led_cdev.cast::>(), + Device, + classdev + ) + }; + from_result(|| { + classdev.handler.brightness_set(brightness)?; + Ok(0) + }) +} + +extern "C" fn blink_set( + led_cdev: *mut bindings::led_classdev, + delay_on: *mut usize, + delay_off: *mut usize, +) -> i32 { + // SAFETY: `led_cdev` is a valid pointer to a `led_classdev` stored in= side a `Device`. + let classdev =3D unsafe { + &*container_of!( + led_cdev.cast::>(), + Device, + classdev + ) + }; + from_result(|| { + classdev.handler.blink_set( + // SAFETY: `delay_on` is guaranteed to be a valid pointer to u= size + unsafe { &mut *delay_on }, + // SAFETY: `delay_on` is guaranteed to be a valid pointer to u= size + unsafe { &mut *delay_off }, + )?; + Ok(0) + }) +} + +#[pinned_drop] +impl PinnedDrop for Device { + fn drop(self: Pin<&mut Self>) { + // 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 e5247f584ad2..f42c60da21ae 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -97,6 +97,7 @@ pub mod jump_label; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod led; pub mod list; pub mod miscdevice; pub mod mm; --=20 2.49.1