pmbus: add PMBus 1.x framework, CLI, and binding

2026-07-13T01:16:57Z

Add U-Boot's PMBus 1.x layer: the decoder/transport library, the pmbus CLI command and a generic DT binding. The subsequent commits provide the UCLASS_REGULATOR adapter and per-chip drivers. U-Boot's PMBus support is not a hwmon clone of Linux's drivers/hwmon/pmbus/. Linux owns the runtime side (polling, sysfs, alert IRQs, fan loops). U-Boot owns the boot-time side in order to, - identify the PMBus regulators a board carries: MFR_ID/ MFR_MODEL/MFR_REVISION + sanity checks. - print telemetry (VIN/VOUT/IIN/IOUT/POUT/TEMP) so an operator can confirm rail voltages and faults before the kernel - decode any chip alerts (STATUS_VOUT/STATUS_IOUT/STATUS_INPUT/ STATUS_TEMPERATURE/STATUS_CML) so a boot log shows why the previous boot failed or the board had been power cycled because of an outage (typically over temperature or under current). Out of scope by design: no periodic polling, no sysfs, no fan-speed control loop, no PMBUS_VIRT_* sensor virtualisation, no caching. If a use case needs any of those, the answer should be "wait until Linux comes up". It shall remain a thin layer. The constants and structural shape (command codes, status bit names, sensor-class enum, format enum, struct pmbus_driver_info) are mirrored from Linux drivers/hwmon/pmbus/pmbus.h verbatim. The decoders/encoders are reimplemented from the PMBus 1.3 specification because the surrounding hwmon context (struct pmbus_data, sysfs caching, hwmon publication) does not apply. The main benefits: - One framework + CLI for any board carrying PMBus regulators: no per-board PMBus implementation required anymore. - Boards call pmbus_print_telemetry() / pmbus_print_status_word() directly from boot init for a snapshot, sharing all decode + format-dispatch with the CLI. - Linux-compatible constants and DT binding so porting an existing drivers/hwmon/pmbus/ chip is mechanical. - Boot-time AVS/VID rail trim reuses the same decoders and encoders as the CLI and the regulator path: no duplicate math. Signed-off-by: Vincent Jardin Signed-off-by: Peng Fan

u-boot.git/cmd/pmbus.c, branch main

pmbus: add PMBus 1.x framework, CLI, and binding