dd_open LFT Device Driver Interface

Kernel and Subsystems Technical Reference, Volume 2

dd_open LFT Device Driver Interface

Purpose

Allocates device driver resources and ensures exclusive access to a device.

Syntax

int dd_open (DevNo, Flag, Chan, Ext)
dev_t DevNo;
long Flag, Chan, Ext;

Description

The dd_open low function terminal (LFT) device driver interface allocates resources needed by a device driver and can be used to ensure exclusive access to a device if necessary.

Parameters

DevNo	Specifies the major and minor device numbers.
Flag	Specifies the open file control flags.
Chan	Specifies the channel number (multiplexed devices only).
Ext	Specifies the extension parameter for device-dependent functions.

Return Values

If successful, the dd_open device driver interface returns a value of 0. Otherwise, a value of 1 is returned and the errno global variable is set to indicate the error.