Man page 9 : parport_write

parport_write - write a block of data to a parallel port

ssize_t parport_write(struct parport *  port , const void *  buffer , size_t  len );

port
    port to write to

buffer
    data buffer (in kernel space)

len
    number of bytes of data to transfer

This will write up to len bytes of buffer to the port specified, using the IEEE 1284 transfer mode most recently negotiated to (using parport_negotiate), as long as that mode supports forward transfers (host to peripheral).

It is the callerAqs responsibility to ensure that the first len bytes of buffer are valid.

This function returns the number of bytes transferred (if zero or positive), or else an error code.