The built-in parallel port on the SGI O2 workstation (a.k.a. IP32) is an IEEE 1284 parallel port driven by a Texas Instrument TL16PIR552PH chip (at least on my R5000). This chip supports SPP, bidirectional, EPP and ECP modes. It has a 16 byte FIFO buffer and supports DMA transfers.
The parallel port connector is an IEEE 1284-C connector. The cable pin-out assignments can be found on SGI TPL (Hardware: End-User/O2_OG - Appendix A. Technical Specifications).
Theoretically, we could simply use the parport_pc module. It is however not so simple. The parport_pc code assumes that the parallel port registers are port-mapped. On the O2, they are memory-mapped. Furthermore, each register is replicated on 256 consecutive addresses (as it is for the built-in serial ports on the same chip).
That's why I wrote a low-level parallel port driver for the built-in port on SGI IP32. The module is named parport_ip32. The latest Linux kernel patch is available here. The patch is normally against the latest 2.6 Linux/MIPS kernel at published date.
The module supports the following parameters:
The driver (in its 0.6 version) has been included in Linux 2.6.16-rc3.
What remains to do:
All tests were done with an HP LaserJet 5MP connected to a R5000 SGI O2.
See the full ChangeLog for more details.
parport_ip32: SGI IP32 built-in parallel port driver v0.6 parport_ip32: Compiled on Jan 24 2006, 21:31:04 parport_ip32: 0x1f380000: Found working ECR register parport_ip32: 0x1f380000: PWord is 8 bits parport_ip32: 0x1f380000: FIFO is 16 PWords deep parport_ip32: 0x1f380000: writeIntrThreshold is 12 parport_ip32: 0x1f380000: readIntrThreshold is 12 parport_ip32: 0x1f380000: Interrupt support enabled parport_ip32: 0x1f380000: DMA support enabled parport_ip32: 0x1f380000: Hardware support for SPP mode enabled parport_ip32: 0x1f380000: Hardware support for EPP mode enabled parport_ip32: 0x1f380000: Hardware support for ECP mode enabled parport0: SGI IP32 at 0x1f380000 (0x1f388000), irq 49 [PCSPP,TRISTATE,COMPAT,EPP,ECP,DMA] parport0: Printer, Hewlett-Packard HP LaserJet 5MP lp0: using parport0 (interrupt-driven).
If you actually tried this driver, I would appreciate your feedback. Just send me a mail at <firstname.lastname@example.org>.