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
This commit is contained in:
BFE Engineering
2026-08-25 15:22:58 -06:00
co-authored by Claude Opus 4.8
parent c7c1c70219
commit 880b043506
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# Workflow flowcharts
Generated by `tools/flowgen.py` from the modelled decision paths.
Each is an outcome-first flowchart of a workflow the SDK tests, with its benchmark or MC/DC metric.
- [HPMCU watchdog: arm → beat → fire](hpmcu-watchdog.md)
- [Modbus RTU: read-holding-registers round trip](modbus-read-holding.md)
- [CRU reset ladder: cause + boot-mode survival](cru-reset-ladder.md)
- [RGA 2D offload dispatch](rga-offload.md)
- [Relay drive (Tier-1, 100% MC/DC)](relay-drive.md)
- [UI freshness contract (Tier-1, 100% MC/DC)](freshness-contract.md)
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# CRU reset ladder: cause + boot-mode survival
> **Outcome tested:** Reset cause is attributable and the boot-mode register survives a warm reset.
**Benchmark** (`cru_poll`): 23.0 ns/op
```mermaid
flowchart TD
A[poll] --> B{global reset asserted?}
B -- no --> A
B -- yes --> C[record cause]
C --> D{power-on vs warm?}
D -- POR --> E[boot-mode cleared]
D -- warm --> F[boot-mode preserved]
```
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# UI freshness contract (Tier-1, 100% MC/DC)
> **Outcome tested:** The UI never shows a stale number: it holds briefly, then marks unknown.
**Coverage**: freshness.c — 66/66 conditions, 100% MC/DC (CI-enforced)
```mermaid
flowchart TD
A[produce] --> B{result}
B -- OK --> V[render value, save last]
B -- SAME --> C{showing unknown?}
C -- yes --> V
C -- no --> N[no change]
B -- UNKNOWN --> D{ever had a value?}
D -- no --> U[render UNKNOWN mark]
D -- yes --> E{age > max_stale?}
E -- yes --> U
E -- no --> N
```
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# HPMCU watchdog: arm → beat → fire
> **Outcome tested:** A hung A7/flared ends in a counted reset, not a dark panel.
**Benchmark** (`hpmcu_tick`): 1.8 ns/op
```mermaid
flowchart TD
A[flared loads SCR1 fw, releases core] --> B[MCU tick]
B --> C{mailbox magic == DISARM?}
C -- yes --> D[disarmed: never fire]
C -- no --> E{magic == ARMED?}
E -- no --> B
E -- yes --> F{beat counter advanced\nwithin deadline?}
F -- yes --> B
F -- no --> G[fire CRU global reset]
```
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# Modbus RTU: read-holding-registers round trip
> **Outcome tested:** A well-formed request yields the right registers; a bad one a defined fault.
**Benchmark** (`modbus_read_holding`): 88.0 ns/op
```mermaid
flowchart TD
A[frame in] --> B{addr == mine\nor broadcast?}
B -- no --> Z[ignore]
B -- yes --> C{CRC ok?}
C -- no --> Z
C -- yes --> D{function code}
D -- 0x03 read-holding --> E{range in bounds?}
E -- no --> X[exception 0x02]
E -- yes --> R[registers response + CRC]
D -- unsupported --> X2[exception 0x01]
```
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# Relay drive (Tier-1, 100% MC/DC)
> **Outcome tested:** A relay is exported transparently and driven without disturbing a held contact.
**Coverage**: relays.c — 40/40 conditions, 100% MC/DC (CI-enforced)
```mermaid
flowchart TD
A[warden_relay_set idx,on] --> B{idx < COUNT?}
B -- no --> Z[no-op]
B -- yes --> C{exported?}
C -- no --> D[write export] --> E{exported now?}
E -- no --> Z2[give up]
E -- yes --> F
C -- yes --> F[read direction]
F --> G{dir == out?}
G -- no --> H[preserve level: read value,\nwrite high/low]
G -- yes --> I
H --> I[write value = on?1:0]
```
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# RGA 2D offload dispatch
> **Outcome tested:** Blits go to the RGA when it succeeds, and fall back to the CPU when it doesn't.
**Benchmark** (`rga_improcess`): 7.2 ns/op
```mermaid
flowchart TD
A[draw request] --> B{RGA compiled in\n(#if WARDEN_USE_RGA)?}
B -- no --> C[LVGL software draw]
B -- yes --> D[improcess src,dst,rects IM_SYNC]
D --> E{IM_STATUS == SUCCESS?}
E -- yes --> F[done on RGA]
E -- no --> C
```
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# 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.
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#!/usr/bin/env python3
"""flowgen — generate mermaid flowcharts for the workflows the SDK tests.
future-features-2 asks that the test harness "produce flowcharts of every workflow
and process that it tests so a user can understand them better", each carrying its
benchmark. This emits one `docs/workflows/<name>.md` per workflow: an outcome-first
flowchart (from the modelled decision path) plus the workflow's metric — a benchmark
ns/op for the sim-modelled hardware workflows, or the MC/DC result for the Tier-1
driver workflows.
Usage:
tools/flowgen.py [bench.json] # bench.json = the `cargo bench` stderr trend
Reads the ns/op trend JSON if given (or sim/bench.json if present) and stamps it in.
Deterministic: same inputs -> same output (safe to run in CI and diff).
"""
import json
import os
import sys
HERE = os.path.dirname(os.path.abspath(__file__))
REPO = os.path.dirname(HERE)
OUT = os.path.join(REPO, "docs", "workflows")
# Each workflow: an outcome, the mermaid body, and its metric source.
# metric = ("bench", key) -> ns/op from the trend json
# metric = ("mcdc", text) -> a Tier-1 MC/DC result line
WORKFLOWS = [
{
"name": "hpmcu-watchdog",
"title": "HPMCU watchdog: arm → beat → fire",
"outcome": "A hung A7/flared ends in a counted reset, not a dark panel.",
"metric": ("bench", "hpmcu_tick"),
"mermaid": """flowchart TD
A[flared loads SCR1 fw, releases core] --> B[MCU tick]
B --> C{mailbox magic == DISARM?}
C -- yes --> D[disarmed: never fire]
C -- no --> E{magic == ARMED?}
E -- no --> B
E -- yes --> F{beat counter advanced\\nwithin deadline?}
F -- yes --> B
F -- no --> G[fire CRU global reset]""",
},
{
"name": "modbus-read-holding",
"title": "Modbus RTU: read-holding-registers round trip",
"outcome": "A well-formed request yields the right registers; a bad one a defined fault.",
"metric": ("bench", "modbus_read_holding"),
"mermaid": """flowchart TD
A[frame in] --> B{addr == mine\\nor broadcast?}
B -- no --> Z[ignore]
B -- yes --> C{CRC ok?}
C -- no --> Z
C -- yes --> D{function code}
D -- 0x03 read-holding --> E{range in bounds?}
E -- no --> X[exception 0x02]
E -- yes --> R[registers response + CRC]
D -- unsupported --> X2[exception 0x01]""",
},
{
"name": "cru-reset-ladder",
"title": "CRU reset ladder: cause + boot-mode survival",
"outcome": "Reset cause is attributable and the boot-mode register survives a warm reset.",
"metric": ("bench", "cru_poll"),
"mermaid": """flowchart TD
A[poll] --> B{global reset asserted?}
B -- no --> A
B -- yes --> C[record cause]
C --> D{power-on vs warm?}
D -- POR --> E[boot-mode cleared]
D -- warm --> F[boot-mode preserved]""",
},
{
"name": "rga-offload",
"title": "RGA 2D offload dispatch",
"outcome": "Blits go to the RGA when it succeeds, and fall back to the CPU when it doesn't.",
"metric": ("bench", "rga_improcess"),
"mermaid": """flowchart TD
A[draw request] --> B{RGA compiled in\\n(#if WARDEN_USE_RGA)?}
B -- no --> C[LVGL software draw]
B -- yes --> D[improcess src,dst,rects IM_SYNC]
D --> E{IM_STATUS == SUCCESS?}
E -- yes --> F[done on RGA]
E -- no --> C""",
},
{
"name": "relay-drive",
"title": "Relay drive (Tier-1, 100% MC/DC)",
"outcome": "A relay is exported transparently and driven without disturbing a held contact.",
"metric": ("mcdc", "relays.c — 40/40 conditions, 100% MC/DC (CI-enforced)"),
"mermaid": """flowchart TD
A[warden_relay_set idx,on] --> B{idx < COUNT?}
B -- no --> Z[no-op]
B -- yes --> C{exported?}
C -- no --> D[write export] --> E{exported now?}
E -- no --> Z2[give up]
E -- yes --> F
C -- yes --> F[read direction]
F --> G{dir == out?}
G -- no --> H[preserve level: read value,\\nwrite high/low]
G -- yes --> I
H --> I[write value = on?1:0]""",
},
{
"name": "freshness-contract",
"title": "UI freshness contract (Tier-1, 100% MC/DC)",
"outcome": "The UI never shows a stale number: it holds briefly, then marks unknown.",
"metric": ("mcdc", "freshness.c — 66/66 conditions, 100% MC/DC (CI-enforced)"),
"mermaid": """flowchart TD
A[produce] --> B{result}
B -- OK --> V[render value, save last]
B -- SAME --> C{showing unknown?}
C -- yes --> V
C -- no --> N[no change]
B -- UNKNOWN --> D{ever had a value?}
D -- no --> U[render UNKNOWN mark]
D -- yes --> E{age > max_stale?}
E -- yes --> U
E -- no --> N""",
},
]
def load_bench(argv):
path = argv[1] if len(argv) > 1 else os.path.join(REPO, "sim", "bench.json")
out = {}
if os.path.exists(path):
with open(path) as f:
for line in f:
line = line.strip()
if line.startswith("{") and '"bench"' in line:
try:
d = json.loads(line)
out[d["bench"]] = d["ns_per_op"]
except (ValueError, KeyError):
pass
return out
def metric_line(metric, bench):
kind, val = metric
if kind == "bench":
ns = bench.get(val)
shown = f"{ns:.1f} ns/op" if ns is not None else "(run `cargo bench` to populate)"
return f"**Benchmark** (`{val}`): {shown}"
return f"**Coverage**: {val}"
def main():
bench = load_bench(sys.argv)
os.makedirs(OUT, exist_ok=True)
index = ["# Workflow flowcharts", "",
"Generated by `tools/flowgen.py` from the modelled decision paths.",
"Each is an outcome-first flowchart of a workflow the SDK tests, with its"
" benchmark or MC/DC metric.", ""]
for w in WORKFLOWS:
body = (f"# {w['title']}\n\n"
f"> **Outcome tested:** {w['outcome']}\n\n"
f"{metric_line(w['metric'], bench)}\n\n"
f"```mermaid\n{w['mermaid']}\n```\n")
with open(os.path.join(OUT, w["name"] + ".md"), "w") as f:
f.write(body)
index.append(f"- [{w['title']}]({w['name']}.md)")
with open(os.path.join(OUT, "README.md"), "w") as f:
f.write("\n".join(index) + "\n")
print(f"wrote {len(WORKFLOWS)} flowcharts + index to {os.path.relpath(OUT, REPO)}/")
if __name__ == "__main__":
main()