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preference=encrypt Implement the abstractions needed for multicolor led class devices, including: * `led::MultiColor` - the led mode implementation * `MultiColorSubLed` - a safe wrapper arround `mc_subled` * `led::MultiColorDevice` - a safe wrapper around `led_classdev_mc` * `led::DeviceBuilder::build_multicolor` - a function to register a new multicolor led class device Signed-off-by: Markus Probst --- rust/bindings/bindings_helper.h | 1 + rust/kernel/led.rs | 34 +++- rust/kernel/led/multicolor.rs | 442 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 476 insertions(+), 1 deletion(-) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 3791af0aadc7..3dba24b364ad 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -70,6 +70,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/kernel/led.rs b/rust/kernel/led.rs index c17f8ef75006..4b66fe41a80c 100644 --- a/rust/kernel/led.rs +++ b/rust/kernel/led.rs @@ -30,8 +30,16 @@ types::Opaque, // }; +#[cfg(CONFIG_LEDS_CLASS_MULTICOLOR)] +mod multicolor; mod normal; +#[cfg(CONFIG_LEDS_CLASS_MULTICOLOR)] +pub use multicolor::{ + MultiColor, + MultiColorDevice, + MultiColorSubLed, // +}; pub use normal::{ Device, Normal, // @@ -233,7 +241,24 @@ pub enum Color { Violet = bindings::LED_COLOR_ID_VIOLET, Yellow = bindings::LED_COLOR_ID_YELLOW, Ir = bindings::LED_COLOR_ID_IR, + #[cfg_attr( + CONFIG_LEDS_CLASS_MULTICOLOR, + doc = "Use this color for a [`MultiColor`] led." + )] + #[cfg_attr( + not(CONFIG_LEDS_CLASS_MULTICOLOR), + doc = "Use this color for a `MultiColor` led." + )] + /// If the led supports RGB, use [`Color::Rgb`] instead. Multi = bindings::LED_COLOR_ID_MULTI, + #[cfg_attr( + CONFIG_LEDS_CLASS_MULTICOLOR, + doc = "Use this color for a [`MultiColor`] led with rgb support." + )] + #[cfg_attr( + not(CONFIG_LEDS_CLASS_MULTICOLOR), + doc = "Use this color for a `MultiColor` led with rgb support." + )] Rgb = bindings::LED_COLOR_ID_RGB, Purple = bindings::LED_COLOR_ID_PURPLE, Orange = bindings::LED_COLOR_ID_ORANGE, @@ -274,7 +299,14 @@ fn try_from(value: u32) -> core::result::Result { /// /// Each led mode has its own led class device type with different capabilities. /// -/// See [`Normal`]. +#[cfg_attr( + CONFIG_LEDS_CLASS_MULTICOLOR, + doc = "See [`Normal`] and [`MultiColor`]." +)] +#[cfg_attr( + not(CONFIG_LEDS_CLASS_MULTICOLOR), + doc = "See [`Normal`] and `MultiColor`." +)] pub trait Mode: private::Sealed { /// The class device for the led mode. type Device<'bound, T: LedOps + 'bound>: Deref; diff --git a/rust/kernel/led/multicolor.rs b/rust/kernel/led/multicolor.rs new file mode 100644 index 000000000000..58dd1a12bc3c --- /dev/null +++ b/rust/kernel/led/multicolor.rs @@ -0,0 +1,442 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Led mode for the `struct led_classdev_mc`. +//! +//! C header: [`include/linux/led-class-multicolor.h`](srctree/include/linux/led-class-multicolor.h) + +use core::{ + num::NonZero, + ptr, // +}; + +use crate::{ + sync::atomic::{ + Atomic, + Relaxed, // + }, + types::ScopeGuard, // +}; + +use super::*; + +/// The led mode for the `struct led_classdev_mc`. Leds with this mode can have multiple colors. +pub enum MultiColor {} +impl Mode for MultiColor { + type Device<'bound, T: LedOps + 'bound> = MultiColorDevice<'bound, T>; +} +impl private::Sealed for MultiColor {} + +/// The multicolor sub led info representation. +/// +/// This structure represents the Rust abstraction for a C `struct mc_subled`. +#[repr(C)] +#[derive(Debug)] +#[non_exhaustive] +pub struct MultiColorSubLed { + /// The color of the sub led + pub color: Color, + brightness: Atomic, + intensity: Atomic, + /// The maximum supported intensity value. + /// + /// If None the maximum intensity equals to [`LedOps::MAX_BRIGHTNESS`]. + pub max_intensity: Option>, + /// Arbitrary data for the driver to store. + pub channel: u32, +} + +// SAFETY: `MultiColorSubLed` can be shared among threads. +unsafe impl Sync for MultiColorSubLed {} + +impl Clone for MultiColorSubLed { + fn clone(&self) -> Self { + Self { + color: self.color, + brightness: Atomic::new(self.brightness()), + intensity: Atomic::new(self.intensity()), + max_intensity: self.max_intensity, + channel: self.channel, + } + } +} + +// We directly pass a reference to the `subled_info` field in `led_classdev_mc` to the driver via +// `Device::subleds()`. +// We need safeguards to ensure `MultiColorSubLed` and `mc_subled` stay identical. +const _: () = { + use core::mem::offset_of; + + const fn assert_same_type(_: &T, _: &T) {} + + let rust_zeroed = MultiColorSubLed { + color: Color::White, + brightness: Atomic::new(0), + intensity: Atomic::new(0), + max_intensity: None, + channel: 0, + }; + let c_zeroed = bindings::mc_subled { + color_index: 0, + brightness: 0, + intensity: 0, + max_intensity: 0, + channel: 0, + }; + + assert!(offset_of!(MultiColorSubLed, color) == offset_of!(bindings::mc_subled, color_index)); + assert!( + offset_of!(MultiColorSubLed, brightness) == offset_of!(bindings::mc_subled, brightness) + ); + assert!(offset_of!(MultiColorSubLed, intensity) == offset_of!(bindings::mc_subled, intensity)); + assert!( + offset_of!(MultiColorSubLed, max_intensity) + == offset_of!(bindings::mc_subled, max_intensity) + ); + assert!(offset_of!(MultiColorSubLed, channel) == offset_of!(bindings::mc_subled, channel)); + + assert_same_type(&0u32, &c_zeroed.color_index); + assert_same_type(&0u32, &c_zeroed.brightness); + assert_same_type(&0u32, &c_zeroed.intensity); + assert!(size_of_val(&rust_zeroed.max_intensity) == size_of_val(&c_zeroed.max_intensity)); + assert_same_type(&rust_zeroed.channel, &c_zeroed.channel); + + assert!(size_of::() == size_of::()); +}; + +impl MultiColorSubLed { + /// Create a new multicolor sub led info. + #[inline] + pub const fn new(color: Color) -> Self { + Self { + color, + brightness: Atomic::new(0), + intensity: Atomic::new(0), + max_intensity: None, + channel: 0, + } + } + + /// Set arbitrary data for the driver. + #[inline] + pub const fn channel(mut self, channel: u32) -> Self { + self.channel = channel; + self + } + + /// Set the initial intensity of the subled. + #[inline] + pub const fn initial_intensity(mut self, intensity: u32) -> Self { + self.intensity = Atomic::new(intensity); + self + } + + /// Set the maximum supported intensity of the subled. + #[inline] + pub const fn max_intensity(mut self, max_intensity: NonZero) -> Self { + self.max_intensity = Some(max_intensity); + self + } + + /// The intensity of the sub led. + #[inline] + pub fn intensity(&self) -> u32 { + self.intensity.load(Relaxed) + } + + /// The brightness of the sub led. + #[inline] + pub fn brightness(&self) -> u32 { + self.brightness.load(Relaxed) + } +} + +/// The multicolor led class device representation. +/// +/// This structure represents the Rust abstraction for a multicolor led class device. +#[pin_data(PinnedDrop)] +pub struct MultiColorDevice<'bound, T: 'bound = ()> { + #[pin] + ops: T, + #[pin] + classdev: Opaque, + _p: PhantomData<&'bound ()>, +} + +impl<'init, S: DeviceBuilderState> DeviceBuilder<'init, S> { + /// Registers a new [`MulticolorDevice`]. + pub fn build_multicolor<'bound: 'init, T: LedOps + 'bound>( + self, + parent: &'bound device::Device, + ops: impl PinInit + 'init, + subleds: &'init [MultiColorSubLed], + ) -> impl PinInit, Error> + 'init { + const_assert!(T::MAX_BRIGHTNESS <= i32::MAX.unsigned_abs() || !T::HAS_BRIGHTNESS_GET); + + try_pin_init!(MultiColorDevice { + ops <- ops, + classdev <- Opaque::try_ffi_init(|ptr: *mut bindings::led_classdev_mc| { + let mut colors = [false; bindings::LED_COLOR_ID_MAX as usize]; + for subled in subleds { + if colors[subled.color as usize] { + dev_err!(parent.as_ref(), "duplicate color in multicolor led\n"); + return Err(EINVAL); + } + colors[subled.color as usize] = true; + } + let subleds_box = KBox::pin_slice::<_, _, Error, Error>( + |index| Ok(subleds[index].clone()), + subleds.len(), + GFP_KERNEL, + )?; + let subleds_box_raw = KBox::into_raw(Pin::into_inner(subleds_box)); + + let subled_guard = ScopeGuard::new(|| { + // SAFETY: `subleds_box_raw` is guaranteed to be a valid pointer to + // `[MultiColorSubLed]`. + drop(unsafe { >::from_raw(subleds_box_raw) }); + }); + + // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write. + // `led_classdev_mc` gets fully initialized in-place by + // `led_classdev_multicolor_register_ext` including `mutex` and `list_head`. + unsafe { + ptr.write(bindings::led_classdev_mc { + led_cdev: 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() + }, + num_colors: u32::try_from(subleds_box_raw.len())?, + // CAST: The safeguards in the const block ensure that + // `MultiColorSubLed` has an identical layout to `mc_subled`. + subled_info: subleds_box_raw.cast::(), + }) + }; + + 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_mc`. + to_result(unsafe { + bindings::led_classdev_multicolor_register_ext( + parent.as_ref().as_raw(), + ptr, + if self.name.is_none() { + &raw mut init_data + } else { + core::ptr::null_mut() + }, + ) + })?; + + subled_guard.dismiss(); + + core::mem::forget(self.fwnode); // keep the reference count incremented + + Ok::<_, Error>(()) + }), + _p: PhantomData, + }) + } +} + +impl<'bound, T: 'bound> MultiColorDevice<'bound, T> { + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::MultiColorDevice`. + #[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::MultiColorDevice`. `container_of!` can therefore + // safely calculate the address of the containing struct. + let led_mc_cdev = unsafe { container_of!(led_cdev, bindings::led_classdev_mc, led_cdev) }; + + // SAFETY: It is guaranteed that `led_mc_cdev` points to a `led_classdev_mc` + // field embedded within a valid `led::MultiColorDevice`. `container_of!` can therefore + // safely calculate the address of the containing struct. + unsafe { &*container_of!(Opaque::cast_from(led_mc_cdev), Self, classdev) } + } + + /// Returns the subleds passed to [`Device::new_multicolor`]. + #[inline] + pub fn subleds(&self) -> &[MultiColorSubLed] { + // SAFETY: The existence of `self` guarantees that `self.classdev.get()` is a pointer to a + // valid `led_classdev_mc`. + let raw = unsafe { &*self.classdev.get() }; + // SAFETY: `raw.subled_info` is a valid pointer to `mc_subled[num_colors]`. + // CAST: The safeguards in the const block ensure that `MultiColorSubLed` has an identical + // layout to `mc_subled`. + unsafe { + core::slice::from_raw_parts( + raw.subled_info.cast::(), + // CAST: It is guaranteed that `num_colors` fits into an `usize`. + raw.num_colors as usize, + ) + } + } +} + +impl<'bound, T: LedOps + 'bound> Deref for MultiColorDevice<'bound, T> { + type Target = T; + + fn deref(&self) -> &Self::Target { + &self.ops + } +} + +// SAFETY: A `led::MultiColorDevice` can be unregistered from any thread. +unsafe impl<'bound, T: 'bound + Send> Send for MultiColorDevice<'bound, T> {} + +// SAFETY: `led::MultiColorDevice` can be shared among threads because all methods of `led::Device` +// are thread safe. +unsafe impl<'bound, T: 'bound + Sync> Sync for MultiColorDevice<'bound, T> {} + +struct Adapter> { + _p: PhantomData, +} + +impl> Adapter { + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::MultiColorDevice`. + /// 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::MultiColorDevice`. + let classdev = unsafe { MultiColorDevice::::from_raw(led_cdev) }; + + // SAFETY: `classdev.classdev.get()` is guaranteed to be a pointer to a valid + // `led_classdev_mc`. + unsafe { bindings::led_mc_calc_color_components(classdev.classdev.get(), brightness) }; + + let _ = classdev.brightness_set(brightness); + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::MultiColorDevice`. + /// 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::MultiColorDevice`. + let classdev = unsafe { MultiColorDevice::::from_raw(led_cdev) }; + + // SAFETY: `classdev.classdev.get()` is guaranteed to be a pointer to a valid + // `led_classdev_mc`. + unsafe { bindings::led_mc_calc_color_components(classdev.classdev.get(), brightness) }; + + classdev.brightness_set(brightness)?; + Ok(0) + }) + } + + /// # Safety + /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a + /// `led::MultiColorDevice`. + /// 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::MultiColorDevice`. + let classdev = unsafe { MultiColorDevice::::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::MultiColorDevice`. + /// `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::MultiColorDevice`. + let classdev = unsafe { MultiColorDevice::::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 MultiColorDevice<'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_mc`. + let dev: &device::Device = unsafe { device::Device::from_raw((*raw).led_cdev.dev) }; + + let _fwnode = dev + .fwnode() + // SAFETY: the reference count of `fwnode` has previously been + // incremented in `led::DeviceBuilder::build_multicolor`. + .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_multicolor_register_ext`. + unsafe { bindings::led_classdev_multicolor_unregister(raw) }; + + // SAFETY: `raw` is guaranteed to be a valid pointer to `led_classdev_mc`. + let led_cdev = unsafe { &*raw }; + + // SAFETY: `led_cdev.subled_info` is guaranteed to be a valid pointer to + // `[MultiColorSubLed]` with length of `led_cdev.num_colors`. + // See `led::DeviceBuilder::build_multicolor`. + drop(unsafe { + KBox::from_raw(ptr::slice_from_raw_parts_mut( + led_cdev.subled_info.cast::(), + // CAST: `num_colors` was originally converted from a `usize` in + // `DeviceBuilder::build_multicolor`. Thus it is guaranteed that + // `num_colors` fits into an usize. + led_cdev.num_colors as usize, + )) + }); + } +} -- 2.56.1