From mboxrd@z Thu Jan 1 00:00:00 1970 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 88110443AA3 for ; Thu, 16 Jul 2026 17:51:22 +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=1784224285; cv=none; b=UifS7ejBpSWJ57f443rCIXF+7Pk53V7+OBxrgkm4cZ/9gDT0Tc4NMvBleLTYriW4cPLhvvHfn1yt2aQwbX3zVqRcCB0BkZwD3H7JImqbAMxUC5pynWuDEekMPnhTlOnZoAsrxxsYoxMXwlrGMG6e5+1J1mbP66tBWxVTmA61yRg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784224285; c=relaxed/simple; bh=fdGk/gdmV/cdseByoK3a2f3vDhDE4dxg8Ca14hgbA9Y=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ih4FK3ZGm0dGridEJCiZEBIHnWrmDfxxscp4IVpYDYF6JjhPfUukVngFOCv0OOZQobBK9zOvmfglyqU3Xx2chVPM2zT2t7AEds4q8CCuJ09HJpi4Xb66nCibtjdZDNBsE6OIZDs/y51UV0ZICeXcmn6lbdwnDbRj8Xkk2kypmgA= 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=nOH/ylm6; 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="nOH/ylm6" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 5B719240027 for ; Thu, 16 Jul 2026 19:51:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1784224275; bh=p48Kuv+aM94lHTwtHsul4KgKPZBem/X3NZ8iOmZmqYQ=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=nOH/ylm63hoHDDTyPHKqUrfndjjHh2qYXA8P13vfGr8mbvMsP3Wd5LRviWTO0b83Q 9IdupGUrOVfPCSzPbmL31IuolxnAdTf90F1vIYJ7gIaqAZMTZyJJzQTSfqIlRDjEa5 +d5GBRuCEXfez+vmjp/3tCGLUO58Ndqa/+hxu59GOkyPAEkhN4gT0Cu2+/J5BhRfNM lF0cpRh+Kmh8i3Rz/C5VW1dWEa4UjSk0Opw+j7brflQEB8FirLQ6pHm2gayvHnR0fA ZqunTvkjFOmssonAeky/moc+/R/TPlHVG3hlUyEcRkCS9N4Mgy2Tbt9b7fLvUrwDXZ PVUNB1CgUdVyw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4h1LFC3r1Sz6twJ; Thu, 16 Jul 2026 19:51:11 +0200 (CEST) From: Markus Probst Date: Thu, 16 Jul 2026 17:51:13 +0000 Subject: [PATCH v23 1/3] rust: leds: add basic led classdev abstractions 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: <20260716-rust_leds-v23-1-e91f5b608b56@posteo.de> References: <20260716-rust_leds-v23-0-e91f5b608b56@posteo.de> In-Reply-To: <20260716-rust_leds-v23-0-e91f5b608b56@posteo.de> To: Lee Jones , Pavel Machek , Greg Kroah-Hartman , Dave Ertman , Leon Romanovsky , Miguel Ojeda , Alex Gaynor , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , "Rafael J. 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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::DeviceBuilder` - the builder for the led class device * `led::Device` - a safe wrapper around `led_classdev` Signed-off-by: Markus Probst --- MAINTAINERS | 8 ++ rust/kernel/led.rs | 288 ++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/led/normal.rs | 230 ++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 4 files changed, 527 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 806bd2d80d15..70989c4c693c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -14662,6 +14662,14 @@ F: drivers/leds/ F: include/dt-bindings/leds/ F: include/linux/leds.h +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 +F: rust/kernel/led/ + 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..596975e103b8 --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,288 @@ +// 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, // + }, + error::{ + from_result, + to_result, + VTABLE_DEFAULT_ERROR, // + }, + macros::vtable, + prelude::*, + str::CStrExt, + sync::aref::ARef, + types::Opaque, // +}; + +mod normal; + +pub use normal::Device; + +/// The name of the led is determined by the driver. +pub enum Named {} +/// The name of the led is determined by its fwnode. +pub enum Unnamed {} + +/// How the name of the led should be determined. +pub trait DeviceBuilderState: private::Sealed {} + +impl DeviceBuilderState for Named {} +impl private::Sealed for Named {} +impl DeviceBuilderState for Unnamed {} +impl private::Sealed for Unnamed {} + +/// The builder to register a led class device. +/// +/// See [`LedOps`]. +pub struct DeviceBuilder<'init, S> { + fwnode: Option>, + name: Option<&'init CStr>, + devicename: Option<&'init CStr>, + devname_mandatory: bool, + initial_brightness: u32, + color: Color, + _p: PhantomData, +} + +impl DeviceBuilder<'static, S> { + /// Creates a new [`DeviceBuilder`]. + #[inline] + #[expect( + clippy::new_without_default, + reason = "no need and derive is prevented by S" + )] + pub fn new() -> Self { + Self { + fwnode: None, + name: None, + devicename: None, + devname_mandatory: false, + initial_brightness: 0, + color: Color::default(), + _p: PhantomData, + } + } +} + +impl<'init> DeviceBuilder<'init, Unnamed> { + /// Sets the firmware node. + #[inline] + pub fn fwnode(self, fwnode: Option>) -> Self { + Self { fwnode, ..self } + } + + /// Sets the device name. + #[inline] + pub fn devicename(self, devicename: &'init CStr) -> Self { + Self { + devicename: Some(devicename), + ..self + } + } + + /// Sets if a device name is mandatory. + #[inline] + pub fn devicename_mandatory(self, mandatory: bool) -> Self { + Self { + devname_mandatory: mandatory, + ..self + } + } +} + +impl<'init, S: DeviceBuilderState> DeviceBuilder<'init, S> { + /// Sets the initial brightness value for the led. + /// + /// The default brightness is 0. + /// If [`LedOps::brightness_get`] is implemented, this value will be ignored. + #[inline] + pub fn initial_brightness(self, brightness: u32) -> Self { + Self { + initial_brightness: brightness, + ..self + } + } + + /// Sets the color of the led. + /// + /// This value can be overwritten by the "color" fwnode property. + #[inline] + pub fn color(self, color: Color) -> Self { + Self { color, ..self } + } +} + +impl<'init> DeviceBuilder<'init, Named> { + /// Sets the name of the led. + /// + /// Setting this will prevent the fwnode from being used and prevents automatic name + /// composition. + #[inline] + pub fn name(self, name: &'init CStr) -> Self { + Self { + name: Some(name), + ..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 = platform::Device; +/// const BLOCKING: bool = false; +/// const MAX_BRIGHTNESS: u32 = 255; +/// +/// fn brightness_set<'bound>( +/// &self, +/// _dev: &'bound platform::Device, +/// _classdev: &led::Device<'bound, Self>, +/// _brightness: u32 +/// ) -> Result<()> { +/// // Set the brightness for the led here +/// Ok(()) +/// } +/// } +/// ``` +/// Led drivers must implement this trait in order to register and handle a [`Device`]. +#[vtable] +pub trait LedOps: Send + Sync + 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<'bound>( + &self, + dev: &'bound Self::Bus, + classdev: &Device<'bound, Self>, + brightness: u32, + ) -> Result<()>; + + /// Gets the current brightness level. + fn brightness_get<'bound>( + &self, + dev: &'bound Self::Bus, + classdev: &Device<'bound, Self>, + ) -> Result { + let _ = (dev, classdev); + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Activates hardware accelerated blinking. + /// + /// delays are in milliseconds. If both are zero, a sensible default should 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 hardware accelerated + /// blinking. + /// + /// See also [`LedOps::BLOCKING`]. + fn blink_set<'bound>( + &self, + dev: &'bound Self::Bus, + classdev: &Device<'bound, Self>, + delay_on: &mut usize, + delay_off: &mut usize, + ) -> Result<()> { + let _ = (dev, classdev, delay_on, delay_off); + build_error!(VTABLE_DEFAULT_ERROR) + } +} + +/// Led colors. +#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)] +#[repr(u32)] +#[non_exhaustive] +#[expect( + missing_docs, + reason = "it shouldn't be necessary to document each color" +)] +pub enum Color { + #[default] + White = bindings::LED_COLOR_ID_WHITE, + Red = bindings::LED_COLOR_ID_RED, + Green = bindings::LED_COLOR_ID_GREEN, + Blue = bindings::LED_COLOR_ID_BLUE, + Amber = bindings::LED_COLOR_ID_AMBER, + Violet = bindings::LED_COLOR_ID_VIOLET, + Yellow = bindings::LED_COLOR_ID_YELLOW, + Ir = bindings::LED_COLOR_ID_IR, + Multi = bindings::LED_COLOR_ID_MULTI, + Rgb = bindings::LED_COLOR_ID_RGB, + Purple = bindings::LED_COLOR_ID_PURPLE, + Orange = bindings::LED_COLOR_ID_ORANGE, + Pink = bindings::LED_COLOR_ID_PINK, + Cyan = bindings::LED_COLOR_ID_CYAN, + Lime = bindings::LED_COLOR_ID_LIME, +} +static_assert!(bindings::LED_COLOR_ID_MAX == 15); + +impl Color { + /// Name of the color + #[inline] + pub fn as_c_str(self) -> &'static CStr { + // SAFETY: + // - `self as u8` is a valid led color id. + // - `led_get_color_name` always returns a valid C string pointer. + unsafe { CStr::from_char_ptr(bindings::led_get_color_name(self as u8)) } + } +} + +impl TryFrom for Color { + type Error = Error; + + fn try_from(value: u32) -> core::result::Result { + if value < bindings::LED_COLOR_ID_MAX { + // SAFETY: + // - `Color` is represented as `u32` + // - the static_assert 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) + } + } +} + +mod private { + pub trait Sealed {} +} diff --git a/rust/kernel/led/normal.rs b/rust/kernel/led/normal.rs new file mode 100644 index 000000000000..816db7c57689 --- /dev/null +++ b/rust/kernel/led/normal.rs @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Led mode for the `struct led_classdev`. +//! +//! C header: [`include/linux/leds.h`](srctree/include/linux/leds.h) + +use super::*; + +/// The led class device representation. +/// +/// This structure represents the Rust abstraction for a led class device. +#[pin_data(PinnedDrop)] +pub struct Device<'bound, T: LedOps + 'bound> { + #[pin] + ops: T, + #[pin] + classdev: Opaque, + _p: PhantomData<&'bound ()>, +} + +impl<'init, S: DeviceBuilderState> DeviceBuilder<'init, S> { + /// Registers a new [`Device`]. + pub fn build<'bound: 'init, T: LedOps + 'bound>( + self, + parent: &'bound T::Bus, + ops: impl PinInit + 'init, + ) -> impl PinInit, Error> + 'init { + const_assert!(T::MAX_BRIGHTNESS <= i32::MAX.unsigned_abs() || !T::HAS_BRIGHTNESS_GET); + + try_pin_init!(Device { + ops <- ops, + classdev <- Opaque::try_ffi_init(|ptr: *mut bindings::led_classdev| { + // SAFETY: `try_ffi_init` guarantees that `ptr` is valid 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_callback), + brightness_set_blocking: T::BLOCKING + .then_some(Adapter::::brightness_set_blocking_callback), + brightness_get: T::HAS_BRIGHTNESS_GET + .then_some(Adapter::::brightness_get_callback), + blink_set: T::HAS_BLINK_SET.then_some(Adapter::::blink_set_callback), + max_brightness: T::MAX_BRIGHTNESS, + brightness: self.initial_brightness, + color: self.color as u32, + name: self.name.map_or(core::ptr::null(), CStrExt::as_char_ptr), + ..bindings::led_classdev::default() + }) + }; + + let mut init_data = bindings::led_init_data { + fwnode: self + .fwnode + .as_ref() + .map_or(core::ptr::null_mut(), |fwnode| fwnode.as_raw()), + default_label: core::ptr::null(), + devicename: self + .devicename + .map_or(core::ptr::null(), CStrExt::as_char_ptr), + devname_mandatory: self.devname_mandatory, + }; + + // SAFETY: + // - `parent.as_ref().as_raw()` is guaranteed to be a pointer to a valid + // `device`. + // - `ptr` is guaranteed to be a pointer to an initialized `led_classdev`. + to_result(unsafe { + bindings::led_classdev_register_ext( + parent.as_ref().as_raw(), + ptr, + if self.name.is_none() { + &raw mut init_data + } else { + core::ptr::null_mut() + }, + ) + })?; + + core::mem::forget(self.fwnode); // keep the reference count incremented + + Ok::<_, Error>(()) + }), + _p: PhantomData, + }) + } +} + +impl<'bound, T: LedOps + 'bound> Device<'bound, T> { + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::Device`. + #[inline] + unsafe fn from_raw<'a>(led_cdev: *mut bindings::led_classdev) -> &'a Self { + // SAFETY: The function's contract guarantees that `led_cdev` points to a `led_classdev` + // field embedded within a valid `led::Device`. `container_of!` can therefore + // safely calculate the address of the containing struct. + unsafe { &*container_of!(Opaque::cast_from(led_cdev), Self, classdev) } + } + + #[inline] + fn parent(&self) -> &'bound 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).parent) } + } +} + +// SAFETY: A `led::Device` can be unregistered from any thread. +unsafe impl<'bound, T: LedOps + 'bound + Send> Send for Device<'bound, T> {} + +// SAFETY: `led::Device` can be shared among threads because all methods of `led::Device` +// are thread safe. +unsafe impl<'bound, T: LedOps + 'bound + Sync> Sync for Device<'bound, T> {} + +struct Adapter { + _p: PhantomData, +} + +impl Adapter { + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within 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 = unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T::Bus`. + let parent = unsafe { T::Bus::from_device(classdev.parent()) }; + + let _ = classdev.ops.brightness_set(parent, classdev, brightness); + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::Device`. + /// This function is called on setting the brightness of a led immediately. + 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 = unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T::Bus`. + let parent = 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 within 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 = unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T::Bus`. + let parent = unsafe { T::Bus::from_device(classdev.parent()) }; + + // CAST: Resulting value will be casted back to i32 in the led subsystem. + from_result(|| { + classdev + .ops + .brightness_get(parent, classdev) + .inspect(|val| debug_assert!(*val <= T::MAX_BRIGHTNESS)) + .and_then(|val| Ok(i32::try_from(val)?)) + }) as u32 + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::Device`. + /// `delay_on` and `delay_off` must be valid pointers to `usize` and have + /// 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 = unsafe { Device::::from_raw(led_cdev) }; + // SAFETY: `classdev.parent()` is guaranteed to be contained in `T::Bus`. + let parent = 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<'bound, T: LedOps + 'bound> PinnedDrop for Device<'bound, T> { + fn drop(self: Pin<&mut Self>) { + let raw = self.classdev.get(); + // SAFETY: The existence of `self` guarantees that `self.classdev.get()` is a pointer to a + // valid `led_classdev`. + let dev: &device::Device = unsafe { device::Device::from_raw((*raw).dev) }; + + let _fwnode = dev + .fwnode() + // SAFETY: the reference count of `fwnode` has previously been + // incremented in `led::DeviceBuilder::build`. + .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(raw) }; + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 9512af7156df..09e4cc7a14db 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -90,6 +90,7 @@ pub mod jump_label; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod led; pub mod list; pub mod maple_tree; pub mod miscdevice; -- 2.54.0