This is a 4,8 or 12 port IDE RAID controller. Recent linux kernels (since 2.4.20-something) have native support for these controllers, under the SCSI low-level driver section.
This is particularly the 7x00 or 8x00 PATA or SATA controllers. The 9x00 (also SATA) controllers are a different model, and a different driver.
Uses the 'twe' driver in FreeBSD.