kernel panic when read from device driver

Hi,everyone,
	I am develop a device driver on our custom PPC823 board,the board has linux running on it and everything works well.The device is infact a 8bit fifo,I use CS5 to select it and read data from it,the Address which is selected by CS5 is begin at 0xfff00000.I use ioremap( ) function to read data from the address 0xfff00000,but kernel panic always occured.Does anyone can help me?Any comments would be appreciated.

Thanks,
Derek


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