Linux 5.12 To Allow Voltage/Temperature Reporting On Some ASRock Motherboards

Voltage, temperature, and fan speed reporting among desktop motherboards under Linux remains one of the unfortunate areas even in 2021... Many SIO ICs remain publicly undocumented and the Linux driver support is often left up to the community and usually through reverse-engineering. Thus the mainline Linux kernel support is left to suffer especially among newer desktop motherboards. At least for Linux 5.12 some ASRock motherboards will begin seeing their voltage/temperature reporting now function.

The Linux kernel has supported the Nuvoton NCT6683D SIO chip for temperature, fan speed, and voltage reporting under Linux. But to date it's been known to work on just a number of older Intel motherboards and one or two AMD MSI motherboards. While the NCT6683D has been found on a number of different motherboards, the open-source Linux kernel "nct6683" driver has intentionally limited its support spectrum after finding differences in registers between the limited public documentation and what's been found in production -- including Intel using a special firmware with different register addresses.

With Linux 5.12, ASRock boards (0xe2c) with the NCT6683 IC are now being white-listed as it's been tested to work on the likes of the ASRock X570 Phantom Gaming motherboard. Other ASRock Phantom Gaming motherboards use this same SIO IC as well as the Z370M Pro4, Z270M Pro4, B250M Pro4, and multiple other models. The hope is all these ASRock motherboards will play nicely with this HWMON driver.

The change is queued up as part of HWMON-next material ahead of the Linux 5.12 merge window opening up in February. If you have an ASRock motherboard with this IC, ideally beginning with Linux 5.12 you will see working (and accurate) voltage / temperature / fan speed reporting.