MIPI I3C Host Controller Interface Driver Comes To Linux 5.11

Announced back in 2018 by the MIPI Alliance was the I3C Host Controller Interface (HCI) 1.0 specification whereby a common I3C HCI driver could support a range of multi-vendor sensors and other components relying on I3C.

MIPI wrote at the time, "MIPI I3C HCI defines a common set of capabilities for the host controller and the software interface, allowing for the building of class definitions based on a common set of features. The definition allows for vendor-specific extensions and optimizations."

Two years later, a MIPI I3C Host Controller Interface driver for Linux was published over the summer. But for this initial MIPI I3C HCI driver code there was limited testing due to HCI 1.0 hardware still being scarce even while HCI v1.1 and HCI v2.0 standards are already in the works.

Now after going through the code review and some additional testing, the I3C Host Controller Interface driver is being mainlined in the Linux 5.11 kernel. At least in theory this will allow for varying I3C host controllers to work off the single driver but we'll see how well it works in practice once more devices come to market and how well the upcoming versions of the specification are adopted. Some functionality to this Linux HCI driver are also lacking due to current limitations of the Linux kernel's I3C subsystem.

Those wanting to dig more into this Linux HCI driver work and are interested in I3C as the sensor interface continues to see growing adoption by sensors in the IoT space, check out the kernel pull request landing this new driver. This MIPI I3C HCI driver comes in at just over four thousand lines of new code.