Subject: parallel devices
To: None <port-sparc@NetBSD.ORG>
From: Iain Hibbert <plunky@skate.demon.co.uk>
List: port-sparc
Date: 04/23/1998 12:21:37
Hello

Parallel Devices now, where can I find out something about them?  There
don't seem to be too many in the source tree, and what there is seems to
be lpt.c in various forms.

are there any standard ioctl's that need to be catered for?

since the transfer is completely synchronous and you can only read or
write at any time I guess if you call read() you want to read, and if you
call write() you want to write - any other way to signal the device which
way to expect a transfer?  (I guess it would have to be unbuffered) or is
that all carried out at a higher level of protocol?  (maybe there isn't a
standard..)

the chip I am programming (the CD1400) is going on about timing
considerations in the driver..  you are supposed to set up various timing
constants for optimum performance, how do I work out what these are, or
more to the point, how do I know what data to work from?  It is to do with
the width of the strobe pulse - I can set it to anything between 80ns and
2.55us apparently but what should I aim for in a general purpose parallel
port?  (maybe I should provide an ioctl that sets it if needed..?) 

any ideas and information gratefully received..
iain