Files
bfe-core1106-sdk/drivers/README.md
T
BFE EngineeringandClaude Opus 4.8 880b043506 docs+tools: workflow flowchart harness (P4) + drivers Tier-1/Tier-2 split
- tools/flowgen.py: generates docs/workflows/<name>.md — one outcome-first mermaid
  flowchart per workflow the SDK tests (hpmcu watchdog, modbus read, cru ladder,
  rga offload, relay drive, freshness contract), each stamped with its benchmark
  ns/op or 100% MC/DC result. Deterministic; reads the cargo-bench trend json.
- drivers/README.md: honest Tier-1 (relays + freshness, 100% MC/DC here now) vs
  Tier-2 (modbus/rga — serious testing + fault-injection + benchmarks via sim
  models; driver sources migrate in with the flare-edge unification) per ADR-0002/0005.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017wB8KB3MMQztRDXCMCkPrf
2026-08-25 15:22:58 -06:00

2.5 KiB

drivers/ — our own hardened, hardware-facing drivers

Per ADR-0002 (tiered MC/DC) and ADR-0005 (source-of-truth), our own hardware-facing code migrates here behind a HAL seam and is hardened. "100% MC/DC on 100% of drivers" is infeasible (≈97% of kernel-driver LOC is vendor blobs — AIC8800 alone is 88.5K lines); the realistic, honest target is tiered.

Tier 1 — real 100% MC/DC (here now, CI-enforced)

Self-contained logic with a clean seam, measured to 100% MC/DC (gcc-14 -fcondition-coverage) by the CI mcdc job (make -C drivers/*/test check):

Driver Seam MC/DC
relays/ relay_io vtable (sysfs backend + in-memory fake) 40/40 conditions, 100%
freshness/ produce/render callbacks (the "no stale numbers" guard) 66/66 conditions, 100%

Adding a Tier-1 driver: copy <name>.{c,h} here, put the hardware/OS calls behind a small injectable seam, then mirror relays/test/ (a fake backend for the logic branches + a real backend over a scratch tree for the plumbing) and enforce-mcdc.sh. The CI job picks up any drivers/*/test/Makefile automatically.

Tier 2 — serious testing + fault-injection + benchmarks

Drivers too large or too vendor/UI-coupled for literal MC/DC get fault-injection, branch coverage, and benchmarks against the simulator instead. Their hardware side is already modelled and tested here in ../sim/:

Driver Serious-testing status SDK model
modbus_engine.c (RS485 master) 11 pty scenarios + fault-injection + a compiled corpus walk (flare-edge tools/modbus-sim/, green) sim::modbus RTU slave (11 tests, silent-drop/forced-NAK faults) + modbus_read_holding benchmark
warden_rga.c (RGA offload) offload-dispatch + CPU-fallback logic sim::rga recording improcess fake (programmable IM_STATUS) + rga_improcess benchmark
HPMCU supervisor (hpmcu.rs) arm/beat/fire + boot-grace safety property sim::hpmcu (8 tests) + hpmcu_tick benchmark

Why the Tier-2 source isn't vendored here yet: modbus_engine.c and warden_rga.c pull in shared UI headers (platform.h, settings.h, lv_*) and librga. Copying those in would duplicate exactly the shared surface the flare-edge↔warden-sdk unification (ADR-0003/0005, a separate [maintainer]-gated step) is meant to resolve cleanly. So the Tier-2 models (the hardware ends) live here now; the Tier-2 driver sources migrate in with the unification, at which point their existing flare-edge harnesses point at this repo.