Add deterministic S5 (soft-off) state derivation and structured error
handling to acpid. Derive S5 parameters once at startup (or retry at
shutdown if AML was not ready) instead of re-parsing the _S5 package
on every shutdown attempt. Replace unit-return set_global_s_state()
with ShutdownResult enum for proper error propagation and fallback
handling.
Changes:
- S5State struct caches SLP_TYPa/b, PM1a/b ports, derivation timestamp
- ShutdownError enum: MissingFadt, Pm1aZero, AmlNotReady, S5NotFound,
S5NotPackage, SlpTypNotInteger, S5WriteFailed
- ShutdownResult enum: Ok, FallbackReset, Err(ShutdownError)
- derive_s5_state() method with early init attempt and lazy fallback
- set_global_s_state() returns ShutdownResult instead of ()
- Early S5 derivation in AcpiContext::init() logs AML readiness status
- main.rs logs shutdown result for debugging
This is W2.1/W2.2 from ACPI-IMPROVEMENT-PLAN.md.
vasilito
2a5eff93ec