[U-Boot-Users] I can not drive CS8900 on mx1ads by U-boot-1.1.1-imx1

[齐尧]

    I have downloaded u-boot-1.1.1 amd u-boot-1.1.1-imx1.diff,and I have cross-compile them successfully.luckly,the bootloader can init the serial port.then ,I want to enable the CS8900,but failed.
    I used to boot mx1ads by BLOB,and blob can get the ID of cs8900 correctly,so I cpoy these codes in blob to U-boot,but these codes are useless to get the ID of CS8900.The codes are as follows:
    unsigned short  c;

         //set chip select 4 upper control register
        *(volatile P_U32)(0x00220020)  = 0x00000F00;
        //set chip select 4 lower control register
        *(volatile P_U32)(0x00220024)  = 0x80001501;
        //p the GPIO muxing to use Chip Select 4
        *(volatile unsigned int *)(0x0021C020) &= 0xFF3FFFFF;
        *(volatile unsigned int *)(0x0021C038) &= 0xFF3FFFFF;
        //QiYao change the GPIO pin to PortC pin 17
        *((volatile unsigned int * ) 0x0021c220)&=~0x00020000;
        *((volatile unsigned int *)  0x0021c238)&=~0x00020000;

         c = *(volatile unsigned short *)(0x15000300);//The Base address of CS8900
            
        CS8900_PPTR = regno;
        printf("CS8900_PDATA = %x\n",CS8900_PDATA);
        
        I have check the codes for some times ,and i dnot know where the mistake is,so i ask you to help me.

       Qiyao , Beijing Institute of Technology