New Linux Patches For AMD i2c Bus Sharing With The PSP

Written by Michael Larabel in AMD on 23 December 2021 at 04:58 AM EST. 3 Comments
The newest Linux hardware support patches for the kernel revolve around i2c bus sharing support for newer SoCs where the i2c bus is being shared by AMD's Platform Security Processor (PSP). This i2c controller is based on common DesignWare IP but new kernel code is being crafted for handling that bus sharing between the kernel and the PSP co-processor.

A new patch series is extending the existing designware i2c Linux driver for supporting the i2c controller on some newer SoCs at least of Cezanne era. The x86 cores are sharing the i2c with the PSP with the latter acting as the arbitrator for access.

The in-progress kernel code is establishing a PSP semaphore arbitration mechanism for handling the sharing of i2c support between Linux and the PSP. The notion of i2c sharing isn't entirely new but existing hardware like Intel's Bay Trail employs a similar i2c bus sharing from the platform firmware when using the X-Powers AXP288 PMIC.

This in-progress patch series working on this Designware i2c PSP support isn't from AMD directly but from Jan Dabros of Semihalf, a Polish embedded systems engineering firm.
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