//! Private module for sealed traits.
//!
//! These traits cannot be implemented outside this crate, enabling
//! the sealed trait pattern used throughout the HAL.
/// A trait that is sealed (cannot be implemented outside this crate).
// ── DMA-related sealed traits ─────────────────────────────────────
/// Marker trait for types that can be used as DMA transfer words.
// ── GPIO-related sealed traits ───────────────────────────────────
/// Types that can serve as peripheral inputs (signals from GPIO matrix towards peripherals).
/// Types that can serve as peripheral outputs (signals from peripherals towards GPIO matrix).
// The `DriverMode` / `Blocking` / `Async` marker traits were removed: every
// associated type was the identity (`type Async<D> = D`), nothing referenced
// them, and they advertised an async capability that does not exist. Re-add a
// real driver-mode distinction only when an async executor actually backs it
// (ROADMAP phase 6).