Provides access to the X.25 Interface Co-Processor/2 adapters by way of the X.25 Interface Co-Processor/2 device handler.
The x25sn character special file provides access to the X.25 Interface Co-Processor/2 device handler, which provides access to a X.25 packet switching network. The device handler supports up to four X.25 Interface Co-Processor/2 adapters.
Usage Considerations
When accessing the X.25 Interface Co-Processor/2 device handler, the following should be taken into account:
| Item | Description |
|---|---|
| Driver initialization and termination | The device handler may be loaded and unloaded. The device handler supports the configuration calls to initialize and terminate itself. |
| Special file support | Calls other than the open and close subroutines are discussed based on the mode in which the device handler is operating. |
Subroutine Support
The X.25 Interface Co-Processor/2 device handler provides specific support for the open, close, read, write, and ioctl subroutines.
open and close Subroutines
The device handler supports the /dev/x25sn special file as a character-multiplex special file. The special file must be opened for both reading and writing (O_RDWR). There are no particular considerations for closing the special file. The special file name used in an open call differs depending upon how the device is to be opened. For each of the following types of special files, the value n is 0 <= n <= 7:
| Item | Description |
|---|---|
| /dev/x25sn | Starts the device handler on the next available port. |
| /dev/x25sn/D | Opens the device handler for the specified port in Diagnostic mode. |
| /dev/x25sn/M | Opens the device handler for reading and writing data to the monitor facilities on the X.25 Interface Co-Processor/2. |
| /dev/x25sn/R | Opens the device handler for updating the routing table. |
read Subroutine
Can take the form of a read, readx, readv, or readvx subroutine. For this call, the device handler copies the data into the buffer specified by the caller.
write Subroutine
Can take the form of a write, writex, writev, or writevx subroutine. For this call, the device handler copies the user data into a kernel buffer and transmits the data on the network.
ioctl Subroutine
The device handler supports the following ioctl operations:
| Item | Description |
|---|---|
| CIO_DNLD | Downloads a task. |
| CIO_GET_STAT | Gets device statistics. |
| CIO_HALT | Halts a session. |
| CIO_QUERY | Queries a device. |
| CIO_START | Starts a session. |
| IOCINFO | Identifies a device. |
| X25_ADD_ROUTER_ID | Adds a router ID. |
| X25_COUNTER_GET | Gets a counter. |
| X25_COUNTER_READ | Reads the contents of a counter. |
| X25_COUNTER_REMOVE | Removes a counter from the system. |
| X25_COUNTER_WAIT | Waits for the contents of counters to change. |
| X25_DELETE_ROUTER_ID | Deletes a router ID. |
| X25_DIAG_IO_READ | Reads to an I/O register on the X.25 Interface Co-Processor/2. |
| X25_DIAG_IO_WRITE | Writes to an I/O register on the X.25 Interface Co-Processor/2. |
| X25_DIAG_MEM_READ | Reads memory from the X.25 Interface Co-Processor/2 into a user's buffer. |
| X25_DIAG_MEM_WRITE | Writes memory to the X.25 Interface Co-Processor/2 from a user's buffer. |
| X25_DIAG_TASK | Provides the means to download the diagnostics task on to the card. |
| X25_LINK_CONNECT | Connects a link. |
| X25_LINK_DISCONNECT | Disconnects a link. |
| X25_LINK_STATUS | Returns the status of the link.
|
Error Conditions
The following error conditions may be returned when accessing the device handler through the /dev/x25sn special file:
| Item | Description |
|---|---|
| EACCES | Indicates that the call application does not have the required authority. |
| EAGAIN | Indicates there were no packets to be read or the transmit queue is full, and the device was opened with the DNDELAY flag set. |
| EBUSY | Indicates that the device was busy and could not accept the operation. |
| EFAULT | Indicates that an invalid address was specified. |
| EIDRM | Indicates that the counter has been removed. |
| EINTR | Indicates that the subroutine call was interrupted. |
| EINVAL | Indicates that an invalid parameter was passed to one of the subroutine calls. |
| EIO | Indicates that an error has occurred. The status field in the status-control block contains more information. |
| EMSGSIZE | Indicates that the data to be given to the user was greater than the length of the buffer specified. The data in the buffer is truncated. |
| ENOBUFS | Indicates that no buffers are available. |
| ENODEV | Indicates that the device requested does not exist. |
| ENOMEM | Indicates that the X.25 device handler was unable to allocate space required for the open. |
| ENOSPC | Indicates that there are no counters available to allocate. |
| ENXIO | Indicates that the device was not completely configured. Initial configuration must be completed before any starts can be issued. |
| EPERM | Indicates the user does not have permission to perform the requested operation. |