From nobody Mon Feb 9 12:25:14 2026 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 6168C322B6C for ; Tue, 6 Jan 2026 01:43:00 +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=1767663783; cv=none; b=Ha6VR9TXNP1wwDh25E4bg178+YVnGwKOKe7gmRtr2Uig27r+6SWLqA8AOhTIjktLW61eIF0brIbpLcoC5S3u8Yl5V/BTRw0YR7NmN92y2NHg7wQg8UPgSRN2RG0CT+SXLCGkHGIkV9HwEmTewJ/gzS3QditKTIYowN4eIZtaMOs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767663783; c=relaxed/simple; bh=NrFVmHpqGiFc4KTRNLdR0xr2E6CieYiGK6FSMD985oE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sT5OpgysOSxF098gz7DQyAx9JxTNocPzRUwj1O1qt0sBYfcblyAtneKeb/H8t5Hvkwwe41q4uxJze+eKZdq3eeYohXI72MuUfA8WNaAiHYS9RyxQXrxabG/nVKgv1SdIY0oNBjm/QQInrnHDaHUZY82mq/ZDbv/kR93P7Wx2v+A= 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=qLpHpgx5; 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="qLpHpgx5" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 2609224002D for ; Tue, 6 Jan 2026 02:42:53 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1767663773; bh=wme5I2kMCGMxH2FpT6bqyV/3UOhpwx7GsUYd9f0Uhv4=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=qLpHpgx5tc7oTEG3ElhrLWJZyJYlJWhlCBlYvS+6MSqIk8EDH3+P13bdz0PgXPK1Y u7PRMuA6NeyDRiAyv2aqqODDf7c1pRYP6KuTwrb9xvjloTrYIZUlL95vzxP0N+to9T 5vB296SKaoJkaHGpKTWaesj0sIK3ZQK4rFemE1R5CXBrqJVxlehN1QmFObpqpyGnEq JqGhFvvscc+qHwzc7xe0/0+FmuNyB5JCU7XAi9BeoMEnC5WRgXW8KOoGkpR5KK4nul JZOsKixd61Cc5Gs6TglpRmYXlnBWxrWCm1yXMceqtPedYcErTtvMnOcPSlW6zxOyU3 QuZtUbRk/3iWg== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4dlYp21lrRz6twR; Tue, 6 Jan 2026 02:42:50 +0100 (CET) From: Markus Probst Date: Tue, 06 Jan 2026 01:42:52 +0000 Subject: [PATCH v10 1/3] rust: leds: add basic led classdev abstractions Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260106-rust_leds-v10-1-e0a1564884f9@posteo.de> References: <20260106-rust_leds-v10-0-e0a1564884f9@posteo.de> In-Reply-To: <20260106-rust_leds-v10-0-e0a1564884f9@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=18142; i=markus.probst@posteo.de; h=from:subject:message-id; bh=NrFVmHpqGiFc4KTRNLdR0xr2E6CieYiGK6FSMD985oE=; b=owEBiQJ2/ZANAwAIATR2H/jnrUPSAcsmYgBpXGiXYDqQ5cytH/Kgla7jO1QBN/cTX+jejIvqd 8re+8X9f8qJAk8EAAEIADkWIQSCdBjE9KxY53IwxHM0dh/4561D0gUCaVxolxsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMSwyLDIACgkQNHYf+OetQ9KbYRAArM8/fS4muuHHc8F5xanwgQLexSIbjhO yyWeUWL80YmyOXB2ELA2sV8xt0rl6fJmTxcXKORZjBy6nv1FmoNifavun8utjXz784s/g02RhKi WFblHdIPYeVezFnoV9GgPWKOyIEmMskYvjw+GL0YqH3wqn6l7fdyGcJwa8/YjxwP3TTSx45WSfC H20/hGqgWnnKYMl0AwLZOWrXKrzuD+TX0WXVZm4OmQO3w4S83NXMUAG3vo1CIU24jHEQ2HwXVV7 gzPFpTkr+lYape1EtQHGEZSCt8cFwaJEJ0ctQ+XtM9zVWAlXFyUe+f7NERlMv11bnY7ghtW/eUl /PQ3oY3lk7x8ue93GnCUWBRPLvKU/ygvXS5NHL7abLpYlttL5kmDoW2gU2ecEHl8qY2aGlO40B8 NVDR/a7dbmul6pORCYkdrnJTH+pFRG+Z43BnYK023/F7bD12ldP65nF2QD9igZYvVduylewHpXy EIJKyrMikuwxHLC2833gFrcPC+shO+LOdR2LwmsAmMjW69pJl5rKg09UqkqhzSDV1bznjC+60Ku j4n/3rfqXojtzQ4U/uf6T/TAt+ZvP7NczLzbXaFy3i5LaY0BPm9RZAtla7DR7WTm8AoqreyQ92d Ay7fh0KUp068NUdvk7LQSGyWCTUBeyfRqNPUnOuT8UO1J2qrJoKo= X-Developer-Key: i=markus.probst@posteo.de; 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preference=encrypt 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 --- MAINTAINERS | 7 + rust/kernel/led.rs | 450 +++++++++++++++++++++++++++++++++++++++++++++++++= ++++ rust/kernel/lib.rs | 1 + 3 files changed, 458 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 765ad2daa218..8c8648a26f93 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -14269,6 +14269,13 @@ F: drivers/leds/ F: include/dt-bindings/leds/ F: include/linux/leds.h =20 +LED SUBSYSTEM [RUST] +M: Markus Probst +L: linux-leds@vger.kernel.org +L: rust-for-linux@vger.kernel.org +S: Maintained +F: rust/kernel/led.rs + LEGO MINDSTORMS EV3 R: David Lechner S: Maintained diff --git a/rust/kernel/led.rs b/rust/kernel/led.rs new file mode 100644 index 000000000000..cdd9b0300b72 --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,450 @@ +// 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, + mem::transmute, + ptr::NonNull, // +}; + +use crate::{ + container_of, + device::{ + self, + property::FwNode, + AsBusDevice, + Bound, // + }, + devres::Devres, + error::{ + from_result, + to_result, + VTABLE_DEFAULT_ERROR, // + }, + macros::vtable, + prelude::*, + str::CStrExt, + 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` with additional +/// fields from `struct led_classdev`. +#[derive(Default)] +pub struct InitData<'a> { + fwnode: Option>, + devicename: Option<&'a CStr>, + devname_mandatory: bool, + initial_brightness: u32, + default_trigger: Option<&'a CStr>, + color: Color, +} + +impl InitData<'static> { + /// Creates a new [`InitData`]. + pub fn new() -> Self { + Self::default() + } +} + +impl<'a> InitData<'a> { + /// Sets the firmware node. + pub fn fwnode(self, fwnode: Option>) -> Self { + Self { fwnode, ..self } + } + + /// Sets the device name. + pub fn devicename(self, devicename: &'a CStr) -> Self { + Self { + devicename: Some(devicename), + ..self + } + } + + /// Sets if a device name is mandatory. + pub fn devicename_mandatory(self, mandatory: bool) -> Self { + Self { + devname_mandatory: mandatory, + ..self + } + } + + /// Sets the initial brightness value for the led. + /// + /// The default brightness is 0. + /// If [`LedOps::brightness_get`] is implemented, this value will be i= gnored. + pub fn initial_brightness(self, brightness: u32) -> Self { + Self { + initial_brightness: brightness, + ..self + } + } + + /// Set the default led trigger. + /// + /// This value can be overwritten by the "linux,default-trigger" fwnod= e property. + pub fn default_trigger(self, trigger: &'a CStr) -> Self { + Self { + default_trigger: Some(trigger), + ..self + } + } + + /// Sets the color of the led. + /// + /// This value can be overwritten by the "color" fwnode property. + pub fn color(self, color: Color) -> Self { + Self { color, ..self } + } +} + +/// Trait defining the operations for a LED driver. +/// +/// # Examples +/// ``` +/// use kernel::{ +/// device, +/// devres::Devres, +/// led, +/// macros::vtable, +/// platform, +/// prelude::*, // +/// }; +/// +/// 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, +/// _classdev: &led::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(), +/// 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, + classdev: &Device, + brightness: u32, + ) -> Result<()>; + + /// Gets the current brightness level. + fn brightness_get(&self, _dev: &Self::Bus, _classdev: &Device) -= > 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, + _classdev: &Device, + _delay_on: &mut usize, + _delay_off: &mut usize, + ) -> Result<()> { + build_error!(VTABLE_DEFAULT_ERROR) + } +} + +/// Led colors. +#[derive(Copy, Clone, Debug, Default)] +#[repr(u32)] +#[non_exhaustive] +#[expect( + missing_docs, + reason =3D "it shouldn't be necessary to document each color" +)] +pub enum Color { + #[default] + White =3D bindings::LED_COLOR_ID_WHITE, + Red =3D bindings::LED_COLOR_ID_RED, + Green =3D bindings::LED_COLOR_ID_GREEN, + Blue =3D bindings::LED_COLOR_ID_BLUE, + Amber =3D bindings::LED_COLOR_ID_AMBER, + Violet =3D bindings::LED_COLOR_ID_VIOLET, + Yellow =3D bindings::LED_COLOR_ID_YELLOW, + Ir =3D bindings::LED_COLOR_ID_IR, + Multi =3D bindings::LED_COLOR_ID_MULTI, + Rgb =3D bindings::LED_COLOR_ID_RGB, + Purple =3D bindings::LED_COLOR_ID_PURPLE, + Orange =3D bindings::LED_COLOR_ID_ORANGE, + Pink =3D bindings::LED_COLOR_ID_PINK, + Cyan =3D bindings::LED_COLOR_ID_CYAN, + Lime =3D bindings::LED_COLOR_ID_LIME, +} + +impl TryFrom for Color { + type Error =3D Error; + + fn try_from(value: u32) -> core::result::Result { + const _: () =3D { + assert!(bindings::LED_COLOR_ID_MAX =3D=3D 15); + }; + if value < bindings::LED_COLOR_ID_MAX { + // SAFETY: + // - `Color` is represented as `u32` + // - the const block above guarantees that no additional color= has been added + // - `value` is guaranteed to be in the color id range + Ok(unsafe { transmute::(value) }) + } else { + Err(EINVAL) + } + } +} + +// 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 { + 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), + max_brightness: T::MAX_BRIGHTNESS, + brightness: init_data.initial_brightness, + default_trigger: init_data.default_trigger + .map_or(core::ptr::null(), CStrExt::as_cha= r_ptr), + color: init_data.color as u32, + ..bindings::led_classdev::default() + }) + }; + + let mut init_data_raw =3D bindings::led_init_data { + fwnode: init_data.fwnode + .as_ref() + .map_or(core::ptr::null_mut(), |fwnode| fwnode= .as_raw()), + default_label: core::ptr::null(), + devicename: init_data + .devicename + .map_or(core::ptr::null(), CStrExt::as_char_pt= r), + 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, + &raw mut init_data_raw, + ) + })?; + + core::mem::forget(init_data.fwnode); // keep the refer= ence 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, classdev, 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, classdev, 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, classdev) + } + + /// # 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, + classdev, + // 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 f812cf120042..231818e0614b 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -108,6 +108,7 @@ pub mod jump_label; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod led; pub mod list; pub mod maple_tree; pub mod miscdevice; --=20 2.51.2