Files
RedBear-OS/drivers/i2c
Red Bear OS 6db0f48170 i2c: review-fix round — hardware-correct DesignWare engine + LPSS bring-up
Post-implementation review returned FAIL with two verified-CRITICAL
findings; all legitimate findings fixed in this round:

CRITICAL — engine wrote IC_CON/IC_TAR while enabled (DesignWare
databook forbids; Linux i2c_dw_xfer_init disables first). Engine
restructured: wait-idle -> disable -> program -> enable with
IC_ENABLE_STATUS polling on every transfer.

CRITICAL — Intel LPSS PCI bring-up skipped parent-device init.
intel-lpss-i2cd now claims functions via pcid_interface
(connect_by_path + enable_device), validates the real BAR size, and
performs intel_lpss_init_dev's sequence (reset-deassert + 64-bit
remap address at BAR0+0x200), ported from Linux drivers/mfd/intel-lpss.c.

MAJOR fixes:
- wait_for checks TX_ABRT before success predicates — a NACKed write
  no longer reports success via post-abort idle state
- SCL timing corrected to Linux's formulas: HCNT uses sda_fall_ns,
  round-to-nearest division (FS 100/200, SS 552/652 for bxt 133 MHz)
- stop=false rejected honestly instead of hanging on the idle wait
- recover(): ABORT-bit cycle + disable + state flush after any failed
  transfer
- validate_request: segment/byte/address/10-bit limits before any MMIO
- i2cd + endpoint: exact-first adapter resolution; last-component
  matching accepted only when unambiguous
- i2cd registration validates provider_scheme as a single safe
  scheme-name component
- I2cTransferResponse gains typed status (I2cTransferStatus,
  serde-defaulted, wire-compatible)
- endpoint::serve takes a Result-returning on_ready callback;
  setrens failure is fatal (fail-closed namespace reduction)
- unexpected i2cd registration responses are fatal for that controller

Tests: dw-i2c 5 (timing vectors, validation, resolution),
intel-lpss-i2cd 1 (PCI ID table coverage), full workspace cargo check
clean, base cooks for x86_64-unknown-redox.

Refs: local/docs/LG-GRAM-16Z90TP-COMPATIBILITY-PLAN.md review-fix round
2026-07-21 12:03:00 +09:00
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