Name: 6 Series/C200 Series Chipset Family 6 port Desktop SATA AHCI Controller
DID 1c02 is the Desktop AHCI controller while 1c03 is the Mobile one.
See the Intel 6 Series Chipset and Intel C200 Series Chipset Specification Update for details
The argument whether certain boards have less than 6 ports is invalid. The chipset provides ports 0-5 but the board vendor might decide not to route all of them to connectors. In IDE mode device 0x1f:2 provides ports 0-3 while device 0x1f:5 provides ports 4-5. In AHCI mode device 0x1f:2 provides ports 0-5.
See the Intel 6 Series Chipset and Intel C200 Series Chipset Datasheet for details