[PARPORT] Device register access

WODECKI, Victor (VWODECKI@baea.com.au)
Tue, 14 Dec 1999 17:06:22 +1030

I have a prototype DSP device which I need to interface to using
Linux, but there's a few things I'm confused about. (Whilst I've
done PCI device drivers before, I'm new to parallel device drivers.)

According to the manufacturer's literature, this device is interfaced
by a PC printer port, IEEE1284, "compatible in the standard
bidirectional mode".

The pseudo code in the data sheet shows that the device is controlled
by accessing its registers, by writing the address of the desired
register into 0x06 and 0x07, and then the data for that register
into 0x00..0x04. However, I'm not sure what these addresses are
relative to.

Presumably, they wouldn't be relative to the base address of the
parallel device (eg 0x378), as that would conflict with status
registers etc.

So is it likely that I should be writing the address of the location
(0x00..0x07) into (eg) 0x378+EPPADDR, and then the data for that
location into (eg) 0x378+EPPDATA?

Or have I misunderstood what the data sheet is saying?

I'm using RH6.1, with a 2.2.13 kernel plus the ppdev3 patch.
The BIOS settings for the PC are:
  Onboard parallel port: 378/IRQ7
  Onboard parallel mode: ECP/EPP
  ECP mode use DMA: 3
  Parallel port EPP type: EPP1.9

Any and all help would be appreciated.

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This archive was generated by hypermail 2.0b3 on Tue 14 Dec 1999 - 01:44:03 EST