pSOSystem System Calls - Read

pSOS+ System Calls de_open
de_open Opens an I/O device.
#include
unsigned long de_open(
unsigned long dev, /* major/minor device number */
void *iopb, /* I/O parameter block address */
void *retval /* return value */
)
Description
Arguments
Return Code
The de_open() call invokes the device open routine of a pSOS+ device driver
specified by the dev argument.
The device open routine can be used to perform functions that need to be done
before the I/O operations can be performed on the device. For example, an
asynchronous serial device driver can reset communication parameters (such as
baud rate and parity) to a known state for the channel being opened.
A device driver can also assign specific duties to the open routine that are not
directly related to data transfer or device operations. For example, a device driver
can use de_open() to enforce exclusive use of the device during several read and/
or write operations.
dev Specifies the major and minor device numbers, which are
stored in the upper and lower 16 bits, respectively.
iopb Points to an I/O parameter block, the contents of which are
driver-specific.
retval Points to a variable that receives a driver-specific value
returned by the driver.
This call returns 0 on success, or an error code on failure. Besides the error codes
listed below, other driver-specific errors may be returned.
pSOSystem System Calls 1-17
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