The
spif driver provides support for the Sun Serial/Parallel Interface card (Sun part number 501-1931) based around the Cirrus Logic CD180 octal serial controller and the Cirrus Logic PPC2 parallel port controller.
The device minor numbers for this driver are encoded as follows:
+---+---+---+---+---+---+---+---+
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
+---+---+---+---+---+---+---+---+
| | | | | | | |
| | | | | +---+---+---> port number
| | | | |
| | | | +---------------> unused
| | | |
| | | +-------------------> dial-out (on tty ports)
| | |
| | +-----------------------> unused
| |
+---+---------------------------> card number
Up to four cards are supported in the system.
Each of the serial ports has an 8 byte FIFO for receive and transmit as well as automatic hardware (RTS/CTS) flow control.