Version 3.1.0

Bugfix:
=======

A call to ioctl, when setting the GPIO pins with command IOCTL_GPIOSET, returns
-EFAULT instead of 0.

Function cp2101_ctlmsg() returns 0 which represents the number of bytes sent
(correct when we set the GPIO pins). This return value is tested in function
cp210x_internal_ioctl() which returns -EFAULT when it's NOT true.

The correct test must rather be that it returns -EFAULT when the return value
is negative (error) or positive (since we haven't sent any byte here), but it
must return 0 if the return value is 0.

Paragon Electronic Design Ltd., Lower Hutt, Nwe Zealand



Driver usage:
=============

Reading GPIO:
-------------

    #define IOCTL_GPIOGET   0x8000
    result = ioctl( usb_fd, IOCTL_GPIOGET, &bits );
  

where:

result:  0 when successful
usb_fd:  File descriptor to the open USB port
bits:    contains the status of the GPIO pins; should be masked with 0x0F
         after read



Writing GPIO:
-------------

    #define IOCTL_GPIOSET   0x8001
    result = ioctl( usb_fd, IOCTL_GPIOSET, bits );


where:

bits: unsigned 16 bit.
      The lowest 4 bits represent the GPIO pins that are affected by the command,
      the same bits in the high byte represent the status of the pins.

      Example:
   
      set bit GPIO pin 2:     bits = ( 4 << 8 ) | 4;
      clear GPIO pin 3:       bits =              8;