关于写C554的寄存器FCR的有关问题

关于写C554的寄存器FCR的问题
诸如   LCR   DLL   DLH   IER等寄存器,我都能写进去,再读出来,可FCR就是不行,
我把代码写在下面,哪位兄弟姐妹指导一下
//定义相关宏
#define   UART_BASE_ADDR                         (0x20300000

#define   C554_CH1_FCR                                       (UART_BASE_ADDR+4)

#ifndef   C554_REG_READ
#define   C554_REG_READ(C554_reg,   result)   \
        result   =   \
                (*(volatile   unsigned   short     *)(C554_reg))   #endif


#ifndef   C554_REG_WRITE
#define   C554_REG_WRITE(C554_reg,   data)   \
        (*(volatile   unsigned   short     *)(C554_reg))   =   \
                (data)
#endif


//写FCR寄存器
C554_REG_WRITE(C554_CH1_FCR,   0,0x1);//   FCR0置1

C554_REG_WRITE(C554_CH1_FCR,   0,0x8f);//   向FCR寄存器写值

[解决办法]
FCR and ISR share the same address space in the UART regsiter set (0x02). The FCR is a write only register and the ISR is a read only register. When you do a write to address 0x02 you write to the FCR register, but when you do a read of address 0x02 you would read the ISR register and not the FCR register.

To overcome this problem you would have to save the FCR value to a variable before you write to the FCR register. And when you want to know what value is in the FCR register, you would read this value from the variable