Copyright (c) 1983 Regents of the University of California.
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@(#)ik.4 6.2 (Berkeley) 06/30/87

C 5 ik - Evans and Sutherland Picture System 300 graphics device interface "device ik0 at vba? csr 0xfffb100 vector ikintr" The ik driver provides access to an Evans and Sutherland Picture System 300 through an Ikon DR-11W interface card. Each two minor device numbers are a different 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 PS300 ``attach'' request being performed while for odd numbered minor devices the attach request is not performed.

All operations between the host and the PS300 utilize DMA. The driver currently supports only ``physical i/o'' operations when reading and writing; this makes the device useless with standard Evans and Sutherland software.

The interface provided by the interface is as UNIX-like as possible. When a device is opened a PS300 attach request is automatically performed. When a device is closed a detach is performed. Reads and writes result in physical i/o requests, but hide all the details of the physical i/o protocol. This is programming style is completely different from the VMS-oriented qio-style interface supplied by Evans and Sutherland.

Reads and writes to the device result in a physical i/o request to the PS300. If a readv (2) or writev (2) call is used, each i/o request results in a single physical i/o request (i.e. the scatter-gather facilities are not supported). In normal operation, the address used in a physical i/o request is the current file offset as specified explicitly with lseek (2) or implictly as a result of reading or writing the device. To specify an address to be used with each physical i/o request, the ik driver interprets the iov entries in a non-standard way. If iov_len is zero, then iov_base is interpreted as an address to be used in the physical i/o request. If the address has the PSIO_SYNC flag or-d into it, the physical 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 PS300 is performed in the driver/controller.

In addition to reading and writing, the following ioctl requests are available:

PSIOLOOKUP

Perform a ``name lookup'' request. The pslookup structure passed indicates the symbol name to be looked up and contains the address returned by the PS300. A zero address return indicates the symbol was undefined.

PSIOGETERROR

In the event of an error, this request may be made to return a more detailed and, sometimes PS300-specific, error code.

/dev/ik[0-7] auto-attach devices

/dev/ik[0-7]d diagnostic interfaces to devices

ik%d: bad cmd %x. An unknown or unsupported command was received by the host.

ik%d: spurious interrupt, code %x. An unexpected interrupt was received from the PS300; the attention code from the PS300 is printed.

ik%d: timeout. A command failed to elicit a response within a reasonable time; the PS300 probably crashed.

An invalid access (e.g. illegal address) to the PS300 can cause the PS300 to crash. It is not always possible to unwedge the PS300 interface hardware hung by an i/o request.