[2218] in linux-scsi channel archive
Questions about low level scsi drivers
daemon@ATHENA.MIT.EDU (Frans van Orsel)
Thu Jul 31 05:48:57 1997
To: linux-scsi@vger.rutgers.edu
Date: Thu, 31 Jul 1997 11:18:43 +0200
From: Frans van Orsel <orsel@cs.utwente.nl>
Hi,
I'm currently working on writing drivers for a PCI card with a number of
devices
on it. One of the devices will be an Adaptec AIC-33C96A chip. (The card isn't
finished yet). I split up the driver design in two drivers, a character
driver to control the other (three) devices and a low-level scsi driver to
control the AIC-33C96A. I just finished the basics of the character driver,
i.e.
framework and detection. Now I would like to start on the low-level driver.
Questions I have:
1. Is there already a low-level driver for this SCSI controller available? I
looked at the aic7xxx driver but I think it is too different from the 33C96A.
The 33C96A uses something calles Write Control Sequences, but I think they
are not the same as the sequences used in the aic7xxx driver.\
2. Is there any documentation on the low-level SCSI interface other than the
source? I really liked the four articles from Alessandro Rubini in Linux
Journal about writing modularized drivers.
3. Is it possible to talk to the driver directly and not through the generic
SCSI driver, for example with IOCTLS? The PCI card has an off-line and on-line
mode. In off-line mode it should act as a normal host adapter giving access to
any devices on the SCSI bus. In on-line mode the controller is used to stream
network data to a SCSI disk. It should not be interrupted by the computer at
this time, but the controller is still controlled by the low-level driver.
What I want is to tell the low-level driver to stop supporting the generic
driver and
any calls from the OS to any device on the SCSI bus and to load a specific
sequence in the controller to enable streaming.
4. Could you give an estimate of how much work/time it takes to write a
complete
low-level driver?
That's all for now, thanks in advance,
Frans Orsel
