The Z8530 layer provides functions to queue packets for transmission. The driver internally buffers the frame currently being transmitted and one further frame (in order to keep back to back transmission running). Any further buffering is up to the caller.
The function z8530_queue_xmit takes a network
buffer in sk_buff format and queues it for transmission. The
caller must provide the entire packet with the exception of the
bitstuffing and CRC. This is normally done by the caller via
the generic HDLC interface layer. It returns 0 if the buffer has been
queued and non zero values for queue full. If the function accepts
the buffer it becomes property of the Z8530 layer and the caller
should not free it.
The function z8530_get_stats returns a pointer
to an internally maintained per interface statistics block. This
provides most of the interface code needed to implement the network
layer get_stats callback.