Introduce a comprehensive abstraction layer for the PWM subsystem to
enable writing drivers in Rust.
Because `Device`, `Chip`, and `PwmOps` all refer to each other, they
form a single, indivisible unit with circular dependencies. They are
introduced together in this single commit to create a complete,
compilable abstraction layer.
The main components are:
- Data Wrappers: Safe, idiomatic wrappers for core C types like
`pwm_device`, and `pwm_chip`.
- PwmOps Trait: An interface that drivers can implement to provide
their hardware-specific logic, mirroring the C `pwm_ops` interface.
- FFI VTable and Adapter: A bridge to connect the high-level PwmOps trait
to the C kernel's pwm_ops vtable.
- Allocation and Lifetime Management: A high-level `Chip::new()`
API to safely allocate a chip and a `Registration` guard that integrates
with `devres` to manage the chip's registration with the PWM core.
An `AlwaysRefCounted` implementation and a custom release handler
prevent memory leaks by managing the chip's lifetime and freeing
driver data correctly.
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://patch.msgid.link/20251016-rust-next-pwm-working-fan-for-sending-v16-3-a5df2405d2bd@samsung.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
d8046cd508