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SSA tmssa Device Driver
Purpose
To provide support for using-system to using-system communications through the SSA
target-mode device driver.
Syntax
#include /usr/include/sys/devinfo.h
#include /usr/include/sys/tmscsi.h
#include /usr/include/sys/scsi.h
#include /usr/include/sys/tmssa.h
Description
The Serial Storage Architecture (SSA) target-mode device driver provides an interface
to allow using-system to using-system data transfer by using an SSA interface.
You can access the data transfer functions through character special files that are
named dev/tmssann.xx, where nn is the node number of the node with which you are
communicating. The xx can be either im (initiator-mode interface), or tm (target-mode
interface). The caller uses the initiator-mode to transmit data, and the target-mode
interface to receive data.
When the caller opens the initiator-mode special file, a logical path is set up. This path
allows data to be transmitted. The user-mode caller issues a write, writev, writex, or
writevx system call to start sending data. The kernel-mode user issues an fp_write or
fp_rwuio service call to start sending data. The SSA target-mode device driver then
builds a send command to describe the transfer, and the data is sent to the device. The
data can be sent as a blocking write operation, or as a nonblocking write operation.
When the write entry point returns, the calling program can access the transmit buffer.
When the caller opens the target-mode special file, a logical path is set up. This path
allows data to be received. The user-mode caller issues a read, readv, readx, or
readvx system call to start receiving data. The kernel-mode caller issues an fp_read or
fp_rwuio service call to start receiving data. The SSA target-mode device driver then
returns data that has been received for the application program.
The SSA target mode device driver allows an initiator-mode device to get access to the
data transfer functions through the write entry point; it allows a target-mode device to
get access through the read entry point.
The only rules that the SSA target mode device driver observes to manage the sending
and receiving of data are:
v Separate write operations need separate read operations.
v Receive buffers that are full, delay the send operation when it tries to resend after a
delay.
Chapter 13. Using the Programming Interface
295
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