centos man page for parport_read

PARPORT_READ(9) 					       Parallel Port Devices						   PARPORT_READ(9)

NAME
       parport_read - read a block of data from a parallel port

SYNOPSIS
       ssize_t parport_read(struct parport * port, void * buffer, size_t len);

ARGUMENTS
       port
	   port to read from

       buffer
	   data buffer (in kernel space)

       len
	   number of bytes of data to transfer

DESCRIPTION
       This will read 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 reverse transfers (peripheral to host).

       It is the caller's responsibility to ensure that the first len bytes of buffer are available to write to.

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

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							   PARPORT_READ(9)