[PATCH v2 0/2] Add UCSI I2C transport driver for ITE885x USB-C controllers

[Edward Blair <edward.blair@gmail.com>]

Some ASUS desktop boards describe the same ITE USB-C controller twice
in ACPI: as an MSFT8000 Resource Hub Proxy and as an ITE885x device at
the same I2C address. If the RhProxy node claims the address first, the
ITE device cannot be registered. Only the ITE node provides the
interrupt required by this transport.

Patch 1 marks the RhProxy node absent only when its I2C resource exactly
matches a supported ITE node which also has an interrupt.

Patch 2 adds the ITE885x UCSI transport. These controllers use
ITE-specific offsets for CCI, MESSAGE_IN, CONTROL and interrupt
handling. They do not expose a VERSION register or accept PPM_RESET
over I2C.

The register layout and reset behaviour were checked against the ITE
Windows driver supplied for this board.

Tested on an ASUS ROG Strix Z790-E Gaming WiFi with ITE8853:

- Built and booted on x86_64.
- ucsi_ite bound to ITE8853:00 without the previous -EBUSY failure.
- /sys/class/typec/port0 was registered.
- USB-C attachment detection worked.
- No UCSI, ITE or Type-C initialization errors were logged.

Suspend/resume and the ITE8800 through ITE8805 IDs have not been tested.

Changes since v1:

- Move the duplicate-device quirk from the I2C core to the ACPI x86
  status-override code, as suggested by Mika and Heikki.
- Correctly identify MSFT8000 as a Resource Hub Proxy.
- Restrict the quirk to exact matching I2C resources.
- Use devm_request_threaded_irq(), as suggested by Heikki.
- Rebase onto Linux 7.2 and update for the current UCSI API.
- Read and cache complete UCSI events before acknowledging them.
- Match the vendor transport's MESSAGE_IN and PPM_RESET behaviour.

Link: https://lore.kernel.org/all/20260314013157.7181-1-edward.blair@gmail.com/

Edward Blair (2):
  ACPI: x86: hide duplicate RhProxy node for ITE UCSI controllers
  usb: typec: ucsi: add ITE885x I2C transport driver

 drivers/acpi/x86/utils.c          | 151 ++++++++++++
 drivers/usb/typec/ucsi/Kconfig    |  11 +
 drivers/usb/typec/ucsi/Makefile   |   1 +
 drivers/usb/typec/ucsi/ucsi_ite.c | 395 ++++++++++++++++++++++++++++++
 4 files changed, 558 insertions(+)
 create mode 100644 drivers/usb/typec/ucsi/ucsi_ite.c


base-commit: 66498c75b4f8017f62d720d9b59675bdf3abce91
-- 
2.55.0