Google Engineers Have Been Working On An AMD SB-TSI Temperature Driver
The SB-TSI (Sideband Temperature Sensor Interface) is a SMBus compatible interface for reading the AMD SoC temperature interface connected to a BMC. The driver was posted this week by Google's Kun Yi who is part of the Google Platforms Infrastructure Server Software team, which doesn't come as much surprise considering the AMD EPYC successes in the data center.
The Sideband Temperature Sensor Interface is publicly documented but has lacked a public Linux driver to this point.
The SBI temperature sensor interface (SB-TSI) is an emulation of the software and physical interface of a typical 8-pin remote temperature sensor (RTS) on AMD SoCs. It implements one temperature sensor with readings and limit registers encode the temperature in increments of 0.125 from 0 to 255.875. Limits can be set through the writable thresholds, and if reached will trigger corresponding alert signals.
The driver amounts to just under 300 lines of code and jives with the Linux kernel's hardware monitoring "hwmon" subsystem. We'll see if it manages to land still for the upcoming Linux 5.7 merge window or gets pushed off for a later cycle.
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