siba(4) - Sonic Inc. Silicon Backplane Driver
This is the interconnect backplane used by the early broadcom SoC and 802.11 devices. It exposes a series of cores behind a bridge interconnect (PCI, SDIO, USB, PCMCIA, etc.)
The siba code is currently a requirement to use dev/bwn(4), which relies on siba enumerating the cores (including the 802.11 core) as well as providing SPROM parsing services, power management (PMU) and clock management.