Intel Has Been Working On MIPI SoundWire Support For Linux

An Intel developer has published testing patches for providing a SoundWire bus driver within the Linux kernel, which implements the MIPI SoundWire 1.1 specification.

For those unfamiliar with SoundWire as was I when coming across these patches, "The SoundWire protocol is a robust, scalable, low complexity, low power, low latency, two-pin (clock and data) multi-drop bus that allows for the transfer of multiple audio streams and embedded control/commands. SoundWire provides synchronization capabilities and supports both PCM and PDM, multichannel data, isochronous and asynchronous modes. SoundWire does borrow a number of concepts from existing interfaces such as HDAudio, AC97, SLIMbus, which already provide control/audio on the same wires, or legacy interfaces such as I2C/I2S, TDM, PDM."

This specification brief from MIPI is a bit oudated but the boasted features for SoundWire include double data-rate, configurable frame size, low complexity, low power, low latency, optional multilane extensions, PDM format, multi-channel data, and a lower gate count.

Unfortunately, more of the details on SoundWire are limited to MIPI members only. Implementing this SoundWire bus driver for the Linux kernel is about eleven thousand lines of code. The "RFC" patches for SoundWire can be found on the kernel mailing list. More information on this SoundWire driver can be found via this documentation patch that describes it in much finer detail.