Performs data structure allocation and initialization for a communications physical device handler (PDH).
#include <sys/device.h> #include <sys/comio.h>
int ddopen (devno, devflag, chan, ext) dev_t devno; ulong devflag; int chan; int ext;
|devno||Specifies major and minor device numbers.|
|devflag|| Specifies the flag word with the following definitions:
|chan||Specifies the channel number assigned by the device handler's ddmpx entry point.|
The ddopen entry point performs data structure allocation and initialization. Hardware initialization and other time-consuming activities such as call initialization are not performed. This call is synchronous and does not return until the open operation is complete.
A ddopen entry point can be called from the process environment only.
In general, communication device handlers use the common return codes defined for an entry point. However, device handlers for specific communication devices can return device-specific codes. The common return codes for the ddopen entry point are:
|EINVAL||Indicates a parameter is not valid.|
|ENODEV||Indicates there is no such device.|
|EBUSY||Indicates the maximum number of opens was exceeded.|
|ENOMEM||Indicates the PDH was unable to allocate needed space.|
|ENOTREADY||Indicates the PDH is in the process of shutting down the adapter.|
|ENXIO||Indicates an attempt was made to open the PDH before it was configured.|
The ddclose entry point, ddopen entry point for kernel-mode processes.