The UCD90xxx family has eight interruptible GPIs (GPIO1 through 4, 12, 16, 17, and 18) that can achieve a faster response. These GPIO pins must be defined as shown in Table 3 to have the interrupt feature enabled.
For more FAQ please check the following document.
UCD90xxx Family Frequently Asked Questions and Answers
UCD9090 UCD9090A UCD90120 UCD90120A UCD90124 UCD90124A UCD90160 UCD90160A UCD90240 UCD90320 UCD90320U