From nobody Fri Dec 19 14:12:48 2025 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 AC3E82798ED for ; Fri, 10 Oct 2025 22:53:58 +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=1760136840; cv=none; b=ojQ7QjxaPmAc7fgGfabVj2jcsY9w3xcR3gy0eK0ytXJRBQG2+vi1S7T2RFPJwziMysNcrrgf9AmF9yovieG9WqQ/gBdVIb3L7KRWag+iulN1eWfJcfanuZUvB39+aMQyo3oqBRPBLnVSwAqAdlpKoi39X36dJ7UyKwI3eNpf3FI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760136840; c=relaxed/simple; bh=TtpRZew8nBO1RLo6hOpzrTr+ya1HsbkgbkHpVhG5Cuk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QotMx/YZdA4+Sad8xOM79PZiRw7ka2Zuq38oYW3TXm1a2q/7qCo6SKT+e5dELabJX6kAQjmC7KlP9mHmvLd5S9Pn00dtu7mJq8pCmb31+e8uH0NGq3jff3KxQj7zcWiOG0ArWRDgtHFyFHk3CiFVqIWwFR3KXs42ZJqfEgUAD1E= 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=iN6vUFpW; 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="iN6vUFpW" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 20FF6240104 for ; Sat, 11 Oct 2025 00:53:57 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1760136837; bh=++GcwuVSuN7C+IBkzeNVpR985xqCXRp0tLupa7tdUzw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:Autocrypt:OpenPGP:From; b=iN6vUFpWiL0sj9n5oHDlqu9c5h4NiarYFN2R2EbbH4IsQ9Lk+knvbMA94VrEQ/wWQ AuiHzK2qOAscakpjY1BrkN3QUuUo1x1YeuXJUO8wOLLCKWFg/OvBlY8kngyF/1nsMx 5iRU7xo7OEAtYCQ6MiRiYwl6qordttjAN3+vTv7YY5DbeqQFt8bK5uS9LUyYoqj1wC w3tE6kgjiGHaBN44V/FeZwCh8AsPy/yZ9ktbsswdpcohJ31zZgu3/d/Jbs102Viv/a FZetV5CUoTrJDuuJA9dKIPnkUjqsp7fKqILsgNTI9xv0QeOddt6Y11dm+41FsC0HSB m0qKgOuy48+Mw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4ck29H3xvSz6tvd; Sat, 11 Oct 2025 00:53:55 +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 v3 2/2] rust: leds: add basic led classdev abstractions Date: Fri, 10 Oct 2025 22:53:56 +0000 Message-ID: <20251010225349.734350-3-markus.probst@posteo.de> In-Reply-To: <20251010225349.734350-1-markus.probst@posteo.de> References: <20251010225349.734350-1-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::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 | 332 +++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 333 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..feac509bda3f --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,332 @@ +// 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}, + 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, led, alloc::KBox, error::Result, macros::vtable}; +/// # use core::pin::Pin; +/// +/// struct MyLedOps; +/// +/// +/// #[vtable] +/// impl led::LedOps for MyLedOps { +/// 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>> { +/// KBox::pin_init(led::Device::new( +/// None, +/// None, +/// led::InitData::new() +/// .default_label(c_str!("my_led")), +/// MyLedOps, +/// )) +/// } +///``` +/// Led drivers must implement this trait in order to register and handle = a [`Device`]. +#[vtable] +pub trait LedOps: Send + 'static + Sized { + /// If set true, [`LedOps::brightness_set`] and [`LedOps::blink_set`] = must not sleep + /// and perform the operation immediately. + const BLOCKING: bool; + /// The max brightness level + const MAX_BRIGHTNESS: u32; + + /// Sets the brightness level. + /// + /// See also [`LedOps::BLOCKING`] + fn brightness_set(&self, brightness: u32) -> Result<()>; + + /// Gets the current brightness level. + fn brightness_get(&self) -> 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, _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 device::Device, + init_data: InitData<'a>, + ops: T, + ) -> impl PinInit, Error> + 'a { + Devres::new( + parent, + 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_callba= ck), + brightness_set_blocking: (!T::BLOCKING) + .then_some(Adapter::::brightness_set_blocki= ng_callback), + brightness_get: T::HAS_BRIGHTNESS_GET + .then_some(Adapter::::brightness_get_callba= ck), + 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_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) } + } +} + +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 _ =3D unsafe { Device::::from_raw(led_cdev) } + .ops + .brightness_set(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`. + unsafe { Device::::from_raw(led_cdev) } + .ops + .brightness_set(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`. + unsafe { Device::::from_raw(led_cdev) } + .ops + .brightness_get() + } + + /// # 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`. + unsafe { Device::::from_raw(led_cdev) }.ops.blink_set( + // 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 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