[PATCH v23 2/3] rust: leds: add Mode trait

[Markus Probst <markus.probst@posteo.de>]

Add the `led::Mode` trait to allow for other types of led class devices
in `led::LedOps`.

Signed-off-by: Markus Probst <markus.probst@posteo.de>
---
 rust/kernel/led.rs        | 27 +++++++++++++++++++++++----
 rust/kernel/led/normal.rs | 22 +++++++++++++++-------
 2 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/rust/kernel/led.rs b/rust/kernel/led.rs
index 596975e103b8..5d7e6d08ad2a 100644
--- a/rust/kernel/led.rs
+++ b/rust/kernel/led.rs
@@ -32,7 +32,10 @@
 
 mod normal;
 
-pub use normal::Device;
+pub use normal::{
+    Device,
+    Normal, //
+};
 
 /// The name of the led is determined by the driver.
 pub enum Named {}
@@ -161,6 +164,7 @@ pub fn name(self, name: &'init CStr) -> Self {
 /// #[vtable]
 /// impl led::LedOps for MyLedOps {
 ///     type Bus = platform::Device<device::Bound>;
+///     type Mode = led::Normal;
 ///     const BLOCKING: bool = false;
 ///     const MAX_BRIGHTNESS: u32 = 255;
 ///
@@ -182,6 +186,11 @@ pub trait LedOps: Send + Sync + Sized {
     #[allow(private_bounds)]
     type Bus: AsBusDevice<Bound>;
 
+    /// The led mode to use.
+    ///
+    /// See [`Mode`].
+    type Mode: Mode;
+
     /// 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;
@@ -194,7 +203,7 @@ pub trait LedOps: Send + Sync + Sized {
     fn brightness_set<'bound>(
         &self,
         dev: &'bound Self::Bus,
-        classdev: &Device<'bound, Self>,
+        classdev: &<Self::Mode as Mode>::Device<'bound, Self>,
         brightness: u32,
     ) -> Result<()>;
 
@@ -202,7 +211,7 @@ fn brightness_set<'bound>(
     fn brightness_get<'bound>(
         &self,
         dev: &'bound Self::Bus,
-        classdev: &Device<'bound, Self>,
+        classdev: &<Self::Mode as Mode>::Device<'bound, Self>,
     ) -> Result<u32> {
         let _ = (dev, classdev);
         build_error!(VTABLE_DEFAULT_ERROR)
@@ -219,7 +228,7 @@ fn brightness_get<'bound>(
     fn blink_set<'bound>(
         &self,
         dev: &'bound Self::Bus,
-        classdev: &Device<'bound, Self>,
+        classdev: &<Self::Mode as Mode>::Device<'bound, Self>,
         delay_on: &mut usize,
         delay_off: &mut usize,
     ) -> Result<()> {
@@ -283,6 +292,16 @@ fn try_from(value: u32) -> core::result::Result<Self, Self::Error> {
     }
 }
 
+/// The led mode.
+///
+/// Each led mode has its own led class device type with different capabilities.
+///
+/// See [`Normal`].
+pub trait Mode: private::Sealed {
+    /// The class device for the led mode.
+    type Device<'bound, T: LedOps<Mode = Self> + 'bound>;
+}
+
 mod private {
     pub trait Sealed {}
 }
diff --git a/rust/kernel/led/normal.rs b/rust/kernel/led/normal.rs
index 816db7c57689..25190486a62d 100644
--- a/rust/kernel/led/normal.rs
+++ b/rust/kernel/led/normal.rs
@@ -6,11 +6,19 @@
 
 use super::*;
 
+/// The led mode for the `struct led_classdev`. Leds with this mode can only have a fixed color.
+pub enum Normal {}
+
+impl Mode for Normal {
+    type Device<'bound, T: LedOps<Mode = Self> + 'bound> = Device<'bound, T>;
+}
+impl private::Sealed for Normal {}
+
 /// 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> {
+pub struct Device<'bound, T: LedOps<Mode = Normal> + 'bound> {
     #[pin]
     ops: T,
     #[pin]
@@ -20,7 +28,7 @@ pub struct Device<'bound, T: LedOps + 'bound> {
 
 impl<'init, S: DeviceBuilderState> DeviceBuilder<'init, S> {
     /// Registers a new [`Device`].
-    pub fn build<'bound: 'init, T: LedOps + 'bound>(
+    pub fn build<'bound: 'init, T: LedOps<Mode = Normal> + 'bound>(
         self,
         parent: &'bound T::Bus,
         ops: impl PinInit<T, Error> + 'init,
@@ -87,7 +95,7 @@ pub fn build<'bound: 'init, T: LedOps + 'bound>(
     }
 }
 
-impl<'bound, T: LedOps + 'bound> Device<'bound, T> {
+impl<'bound, T: LedOps<Mode = Normal> + 'bound> Device<'bound, T> {
     /// # Safety
     /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a
     /// `led::Device`.
@@ -107,17 +115,17 @@ fn parent(&self) -> &'bound device::Device<Bound> {
 }
 
 // SAFETY: A `led::Device` can be unregistered from any thread.
-unsafe impl<'bound, T: LedOps + 'bound + Send> Send for Device<'bound, T> {}
+unsafe impl<'bound, T: LedOps<Mode = Normal> + '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> {}
+unsafe impl<'bound, T: LedOps<Mode = Normal> + 'bound + Sync> Sync for Device<'bound, T> {}
 
 struct Adapter<T: LedOps> {
     _p: PhantomData<T>,
 }
 
-impl<T: LedOps> Adapter<T> {
+impl<T: LedOps<Mode = Normal>> Adapter<T> {
     /// # Safety
     /// `led_cdev` must be a valid pointer to a `led_classdev` embedded within a
     /// `led::Device`.
@@ -210,7 +218,7 @@ impl<T: LedOps> Adapter<T> {
 }
 
 #[pinned_drop]
-impl<'bound, T: LedOps + 'bound> PinnedDrop for Device<'bound, T> {
+impl<'bound, T: LedOps<Mode = Normal> + '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

-- 
2.54.0