ik.4

早期freebsd实现

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.\"     @(#)ik.4	8.1 (Berkeley) 6/5/93
.\"
.Dd June 5, 1993
.Dt IK 4
.Os BSD 4.2
.Sh NAME
.Nm ik
.Nd Evans and Sutherland Picture System 300 graphics device interface
.Sh SYNOPSIS
.Cd "device ik0 at vba? csr 0xfffb100 vector ikintr"
.Sh DESCRIPTION
The
.Nm ik
driver provides access
to an Evans and
Sutherland Picture System 300 through an Ikon
.Tn DR-11W
interface card.
Each two minor device numbers are a different
.Tn PS300 ;
within a pair of device numbers the odd valued
device is used for ``diagnostic'' purposes.   That is,
for even numbered minor devices, opening the device results
in a
.Tn PS300
``attach'' request being performed while for
odd numbered minor devices the attach request is not performed.
.Pp
All operations between the host and the
.Tn PS300
utilize
.Tn DMA .
The driver currently supports only physical
.Tn I/O operations
when reading and writing; this makes the device useless with
standard Evans and Sutherland software.
.Pp
The interface provided by the interface is as
.Ux Ns -like
as possible.
When a device is opened a
.Tn PS300
attach request is automatically
performed.  When a device is closed a detach is performed.  Reads
and writes result in physical
.Tn I/O
requests, but hide all the details
of the physical
.Tn I/O
protocol.  This is programming style is completely
different from the
.Tn VMS Ns -oriented
qio-style interface supplied by Evans
and Sutherland.
.Pp
Reads and writes to the device result in a physical
.Tn I/O
request
to the
.Tn PS300 .
If a
.Xr readv 2
or
.Xr writev 2
call is used, each
.Tn I/O
request results in a single physical
.Tn I/O
request (i.e. the scatter-gather facilities are not supported).
In normal operation, the address used in a physical
.Tn I/O
request
is the current file offset as specified explicitly with
.Xr lseek 2
or implictly as a result of reading or writing the device.
To specify an address to be used with each physical
.Tn I/O
request,
the
.Nm ik
driver interprets the
.Ar iov
entries in a non-standard way.  If
.Ar iov_len
is zero, then
.Ar iov_base
is interpreted as an address to be used in the physical
.Tn I/O
request.  If the address has the
.Dv PSIO_SYNC
flag or-d into it,
the physical
.Tn I/O
request is made as a ``write with sync''.
All addresses and data presented to the driver should be in
the byte order of the host; any byte swapping required to converse
with the
.Tn PS300
is performed in the driver/controller.
.Pp
In addition to reading and writing, the following
.Xr ioctl
requests are available:
.Bl -tag -width PSIOGETERROR
.It Dv PSIOLOOKUP
Perform a ``name lookup'' request.  The
.Ar pslookup
structure passed indicates the symbol name to be looked up
and contains the address returned by the
.Tn PS300 .
A zero
address return indicates the symbol was undefined.
.It Dv PSIOGETERROR
In the event of an error, this request may be made to
return a more detailed and, sometimes
.Tn PS300 Ns -specific ,
error code.
.Sh FILES
.Bl -tag -width /dec/ik[0-7]xx -compact
.It Pa /dev/ik[0-7]
auto-attach devices
.It Pa /dev/ik[0-7]d
diagnostic interfaces to devices
.El
.Sh DIAGNOSTICS
.Bl -diag
.It ik%d: bad cmd %x.
An unknown or unsupported command was received by the host.
.It ik%d: spurious interrupt, code %x.
An unexpected interrupt was received from the
.Tn PS300 ;
the
attention code from the
.Tn PS300
is printed.
.It ik%d: timeout.
A command failed to elicit a response within a reasonable
time; the
.Tn PS300
probably crashed.
.El
.Sh HISTORY
The
Tahoe Version
.Nm
driver appeared in
.Bx 4.2 .
.Sh BUGS
An invalid access (e.g. illegal address) to the
.Tn PS300
can
cause the
.Tn PS300
to crash.  It is not always possible to unwedge
the
.Tn PS300
interface hardware hung by an
.Tn I/O
request.