hwmon: (pmbus) Add MPQ8646 driver

Add a new driver for the MPS MPQ8646 that is a PMBus device.

Beyond basic PMBus telemetry, the driver adds:
  - alarm acknowledge via inX_reset_history.
  - STATUS_WORD MPS-extended bit decode and the NVM-backed
    PROTECTION_LAST post-mortem, exposed as a read-only debugfs
    decoder.
  - In-driver alarm-poll fallback work item (thanks lm90) for
    boards without SMBALERT

Signed-off-by: Vincent Jardin <vjardin@free.fr>
Link: https://lore.kernel.org/r/20260730-mpq8646_v0-v7-3-e7c7ad768d5d@free.fr
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Vincent Jardin 2026-07-30 17:44:01 +02:00 • committed by Guenter Roeck
commit 24be24bebc
6 changed files with 969 additions and 0 deletions