// Copyright (c) 2026 Rigless Labs.
// SPDX-License-Identifier: MIT OR Apache-2.0
//! The chips a board puts on a part's buses, and the seams they attach through.
//!
//! A peripheral of an MCU is `soc`'s; a chip on a board is this module's. The two meet at a trait per bus
//! kind: the controller calls it and knows nothing of what answers, and the chip implements it and knows
//! nothing of registers. That is the whole of the arrangement, and it is why a card can be driven by a host
//! test with no MCU in sight and by a firmware with no test in sight.
//!
//! A chip owns its own document. Nothing here is written against an SoC, and no model here names one: the
//! same card belongs on any part with a card interface, which is the point of it being a chip rather than a
//! peripheral.
//!
//! A bench that wants something known on a bus, rather than the chip that will eventually be there, uses
//! the stand-in the controller's own module keeps — `spi::Pattern` is one. A stand-in answers something
//! recognisable so a controller that never reached it is caught; a chip answers what the part it models
//! would answer. They are different things and they live apart.