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 A70A32F3632 for ; Sun, 13 Sep 2026 16:15:27 +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=1789316130; cv=none; b=ZsYAE6ejs7NFiflPnXw3cY5+Uk/f433oZ3yLNfFpZlnOK9q3oAPvIoi3gUrL+MlD3u8mb9B+Y6CsnOW1989afW0fOjIPqkF8B968fkmtzI1bshwNScA8obHKXftF1jiFUhew2NhlAaydvfwvkR6+U3x9tYSYL8cx6bxJ339QAHs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789316130; c=relaxed/simple; bh=Xn4GIYX+KSS0ezgE+U3dcStxf/TFdWFrcgYbKCNENcc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=KW9Wm9ONIPPXCpR5hdl4ClKcxpD7SElcUY6xexXR57Lxzf0BdnQrs763O3Jz/3Y50X8IbWyANDdcE61uezQKiglmDbezAitike2IwbtULe7Z1CiAZJhgStf57brT1dhT0Gx2+KPvBiOcQDrGK6fV9mAuNHsB5ugJK8ek3E5yQxQ= 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=mukMsm10; 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="mukMsm10" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id EB42F24002E for ; Sun, 13 Sep 2026 18:15:25 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1789316125; bh=iMVmQuBrh2V9IQp0vpDiYlCSTCHfpYJ85NaS0L0yH9U=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=mukMsm10YQkgZEFD9WNlrIsPzQDjHMxss2jW1lMfrDlbzFhaH/Lyh1sQzksn8lpxY xB3E/Bv+fAoJtC06z/KMcXzLSTbFeHlCOAZ3wovvZNYxWylAcGNSJQ9FnGy9GvRa8t 4ikPj5gE3khKomnzRODescBR2ontzsosF7oYck131s+bA1/CEGwfVMYFrYsktCPUSN 3YzLGGnJg2qSP2v4v8FhOzkmqbIGF2WG28OywaF8QCAryGWUQD4A0geKWfmiWLkqsz ay26SIGJ1XKogo/KDzcTmitSSXVxxEIxzPhyLdeEKkrUQN8lkZhL8NC+Q+zabdcjf8 2i4CEsRP4AReQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4hjYKP6PWMz9rxS; Sun, 13 Sep 2026 18:15:21 +0200 (CEST) From: Markus Probst Date: Sun, 13 Sep 2026 16:15:24 +0000 Subject: [PATCH v25 1/4] 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: <20260913-rust_leds-v25-1-1a10371d78c3@posteo.de> References: <20260913-rust_leds-v25-0-1a10371d78c3@posteo.de> In-Reply-To: <20260913-rust_leds-v25-0-1a10371d78c3@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 --- rust/kernel/led.rs | 265 ++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/led/normal.rs | 222 ++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 3 files changed, 488 insertions(+) diff --git a/rust/kernel/led.rs b/rust/kernel/led.rs new file mode 100644 index 000000000000..deda8cc548a8 --- /dev/null +++ b/rust/kernel/led.rs @@ -0,0 +1,265 @@ +// 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, + 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::{ +/// led, +/// macros::vtable, +/// prelude::*, // +/// }; +/// +/// struct MyLedOps; +/// +/// +/// #[vtable] +/// impl led::LedOps for MyLedOps { +/// const BLOCKING: bool = false; +/// const MAX_BRIGHTNESS: u32 = 255; +/// +/// fn brightness_set<'bound>( +/// self: &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 { + /// 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: &Device<'bound, Self>, brightness: u32) -> Result<()>; + + /// Gets the current brightness level. + fn brightness_get<'bound>(self: &Device<'bound, Self>) -> Result { + 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: &Device<'bound, Self>, + delay_on: &mut usize, + delay_off: &mut usize, + ) -> Result<()> { + let _ = (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..a22c29cfd262 --- /dev/null +++ b/rust/kernel/led/normal.rs @@ -0,0 +1,222 @@ +// 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 core::ops::Deref; + +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: '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 device::Device, + 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_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_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: '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) } + } +} + +impl<'bound, T: LedOps + 'bound> Deref for Device<'bound, T> { + type Target = T; + + fn deref(&self) -> &Self::Target { + &self.ops + } +} + +// SAFETY: A `led::Device` can be unregistered from any thread. +unsafe impl<'bound, T: '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: '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) }; + + let _ = classdev.brightness_set(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) }; + + classdev.brightness_set(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) }; + + // CAST: Resulting value will be casted back to i32 in the led subsystem. + from_result(|| { + classdev + .brightness_get() + .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) }; + + classdev.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<'bound, T: '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 4d5c96ddc49c..748788ad131b 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -96,6 +96,7 @@ pub mod jump_label; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod led; pub mod list; pub mod maple_tree; pub mod miscdevice; -- 2.55.0