AMD Posts Proposal & Linux Patches For eSPI Subsystem

AMD has posted patches proposing a new Linux subsystem for the Enhanced Serial Peripheral Interface (eSPI) standard that was in turn originally developed by Intel. With AMD now making use of eSPI, they are proposing a new subsystem for it within the Linux kernel, which includes a new driver for their hardware.

Intel originally developed eSPI as a communication protocol for linking to the BIOS, system controllers, and other peripherals like TPMs as an alternative to the LPC interface, traditional SPI, and other side-band signalling.

After AMD's Krishnamoorthi M inquired on the Linux kernel mailing list whether the AMD eSPI work should be extending the existing SPI subsystem code or introduced as its own new bus type, the patches proposed are doing the latter with an initial user of this subsystem being a new AMD eSPI driver.

This new code has been tested and validated on an AMDI0070 platform and works. Known limitations of the new subsystem include no Device Tree support yet since the AMD code just uses ACPI, slave device enumeration is manual, and some operations will be added in follow-on patches.

Those interested in this AMD eSPI work for the Linux kernel can find the patch series on the kernel mailing list.