.\" $OpenBSD: ss.4,v 1.3 1999/07/07 10:50:10 aaron Exp $
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.\" Copyright (c) 1998 Kenneth Stailey and Ian Darwin
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.Dd September 28, 1998
.Dt SS 4
.Os
.Sh NAME
.Nm ss
.Nd SCSI Scanner device
.Sh SYNOPSIS
.Nm ss* at scsibus? target ? lun ?
.Sh DESCRIPTION
The
.Nm ss
device allows an application to set scanner parameters and retrieve
image data from any of the supported scanners without having to be
concerned with details of its particular command set.
.Pp
The list of supported scanners varies from time to time; at present it
includes HP Scanner Control Language (SCL) SCSI processor type
scanners: Scanjet IIp, IIc, IIcx, 4p and 5p (others will probably work
if the SCSI INQUIRY strings are added to the driver.)  Not recently
tested but worked in the past true SCSI scanners: Mustek 600CX and 1200CX
(these do not do SCSI disconnect-reconnect they will lock up the bus
during operation.  You can use a second controller.)
.Sh KERNEL CONFIGURATION
Obviously a SCSI host adapter must be present in the config file
before this device can be configured.
.Pp
If a count is given, that many 
.Nm ss 
devices will be configured into the kernel.
.Sh IOCTLS
This device provides the
.Nm SCIOCGET
and
.Nm SCIOCSET
ioctls, which respectively get and set a series of parameters
describing the scan to be performed upon subsequent reading of the scanner.
The third argument is the address of a scan_io structure;
details of this structure can be found in the header file
.Nm scanio.h.
.Pp
The 
.Nm SCIOCRESTART
ioctl ignores the third parameter, and restarts the scan.
The
.Nm SCIOC_USE_ADF
ioctl also ignores its third parameter, and tells the scanner
to use its automatic document feeder if it has one.
.Sh EXAMPLE
The normal use of this device in a scanner program would be something
like this:
.nf
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/scanio.h>
struct scan_io sp;
fd = open the driver (/dev/ss0 for the first scanner)
ioctl(fd, SCIOCGET, &sp) to get the scanner parameters.
\&... modify any parameters ...
ioctl(fd, SCIOCSET, &sp) to set the changed parms;
ioctl(fd, SCIOCGET, &sp) to see if things got rounded or truncated
read(fd, somebuf, sp.scan_window_size);
write the data someplace where you want it.
.Sh BUGS
Image data should should either be normalized to a particular format
or some indication as to what the format is should be provided.
Currently scanners return data in a format similar to the data portion
of a Portable Any Map (PNM) as produced by the pbmplus and netpbm
software packages.
.Pp
Even when vendors produce compliant SCSI scanners there is much
variation in what parameters actually work in a SCSI_SET_WINDOW
command.  Back in March 1997 an attempt to deal with this via quirk
tables was started.  There exists some code for Ultima AT3 and A6000C
Plus, Ricoh IS50, IS410, IBM 2456-001, UMAX UC630, and Fujitsu M3096Gm
that use this approach but none of these scanners work yet.
.Pp
Provisional userland programs exist in the source tree in
src/usr.sbin/ssio.  Eventually a program similar to
.Nm chio
or
.Nm mt
will be written.
.Sh SEE ALSO
.Xr scsi 4
.Pp
Documentation from the various scanner vendors.