uclinux PIO device driver interrupt handler not execute

I tried to do couple things in my uClinux device driver to enable the interrupt.

1) Enabling the PIO Core interrupt:

Because my PIO base address is 0x00000060 on the a clock_crossing_bridge w/ base address of 0x08200000, my driver define base address is 0x082000060 (<-Is this correct?)

# define ALTERA_PIO_BASE_ADDRESS 0x08200060

# define ALTERA_OFFSET_DATA 0x00

# define ALTERA_OFFSET_DIRECTION 0x01

# define ALTERA_OFFSET_IRQ_MASK 0x02

# define ALTERA_OFFSET_EDGE_CAPTURE 0x03

...

in probe function I have

volatile int *base_addr = (int *) ALTERA_PIO_BASE_ADDRESS;

...

*(base_addr + ALTERA_OFFSET_IRQ_MASK) = 0x01; //One input PIO from the SMA pin in the DE2-115, rising edge interrupt generator

2) __builtin_wrctl(3, 3); //irq2, write into ienable register (3)

__builtin_wrctl(0, 1); //write 1 into status register (0) to enable PIE

I got Kernel panic - not syncing: Oops

Unable to handle kernel paging request at virtual address 08200000

ea = c70e418c, ra = c70e4178, cause =15

Did I write into or enable the wrong interrupt? my irq_mask is definite not turn on showing in the signaltapII. Any help is greatly appreciated.

Yeung