[RFC PATCH 0/2] rust: LED abstractions

[Fiona Behrens]

This RFC implements a basic LED abstraction to show how this would work with rust.

Currently this just implements a sample driver, to show how to use the abstraction, which just
prints the requested state, supporting a on/off LED and an led with brightness level up to 255 and
hardware blinking. I intend to write a hardware specific driver for submitting.

The abstractions is a generic struct that holds a generic driver data on which the vtable is
implemented. Because this struct also holds the c led_classdev (include/linux/leds.h) struct this
struct is pinned and is using pin_init to create and directly register the LED.
Dropping the struct unregisteres the LED. I plan to also add devm functions later, but as device
abstractions in rust are not yet that far I opted agains that for the first iteration of the LED
abstractions.

This is currently using core::time::Duration for the blinking interval, but will likely change that
to use the Delta time type from FUJITA Tomonori [1].

This is requiring the Opaque::try_ffi_init patch by Alice Ryhl[2] which just got merged into
char-misc-testing.

[1]: https://lore.kernel.org/rust-for-linux/20241005122531.20298-3-fujita.tomonori@xxxxxxxxx/
[2]: https://lore.kernel.org/rust-for-linux/20240926-b4-miscdevice-v1-1-7349c2b2837a@xxxxxxxxxx/

Fiona Behrens (2):
  rust: LED abstraction
  samples: rust: led sample

 rust/kernel/leds.rs      | 399 +++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs       |   2 +
 samples/rust/Kconfig     |  10 +
 samples/rust/Makefile    |   1 +
 samples/rust/rust_led.rs | 103 ++++++++++
 5 files changed, 515 insertions(+)
 create mode 100644 rust/kernel/leds.rs
 create mode 100644 samples/rust/rust_led.rs

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2.46.0