Writing Merlin Drivers

This chapter describes the expected source layout and software contract for Merlin drivers.

For all bus families, the recommended model is:

• declare public, application-facing prototypes in

  include/merlin/platform/api/*.h;

• keep bus-specific enums and configuration structures in

  include/merlin/buses/*.h;

• use drv_status_t (from include/merlin/platform/api/generic.h) as

  the return type of exported driver APIs.

Contents:

• Merlin-based USART driver
  • Public API contract
  • Status model
  • Driver structure and platform integration
  • Probe/init/runtime/release pseudo-code
  • Alias pattern (recommended)
• Merlin-based SPI driver
  • Public API contract
  • Status model
  • Platform descriptor pattern
  • Probe/init/xfer/release pseudo-code
  • Chip-select handling
  • Alias pattern (recommended)
• Merlin-based I2C driver
  • Public API contract
  • Status model
  • Platform descriptor pattern
  • Probe/init/release pseudo-code
  • Read/write operations
  • Alias pattern (recommended)
• Merlin-based USB driver
  • Current API status
  • Recommended transition model
  • Status mapping guidelines
  • Platform integration pattern
  • Note on existing examples