Allocates device driver resources and ensures exclusive access to a device.
int dd_open (DevNo, Flag, Chan, Ext) dev_t DevNo; long Flag, Chan, Ext;
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.
|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.|
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.