代码：
key = 14;
mpll_val = (92<<12)|(1<<4)|(1);
ChangeMPllValue((mpll_val>>12)&0xff, (mpll_val>>4)&0x3f, mpll_val&3);
ChangeClockDivider(key, 12);
cal_cpu_bus_clk();
void ChangeMPllValue(int mdiv,int pdiv,int sdiv)
{
rMPLLCON = (mdiv<<12) | (pdiv<<4) | sdiv;
}
void ChangeClockDivider(int hdivn_val,int pdivn_val)
{
int hdivn=2, pdivn=0;
// hdivn_val (FCLK:HCLK)ratio hdivn
// 11
// 12
// 13
// 14
// pdivn_val (HCLK:PCLK)ratio pdivn
// 11
// 12
switch(hdivn_val) {
case 11: hdivn=0; break;
case 12: hdivn=1; break;
case 13:
case 16: hdivn=3; break;
case 14:
case 18: hdivn=2; break;
}
switch(pdivn_val) {
case 11: pdivn=0; break;
case 12: pdivn=1; break;
}
//Uart_Printf(“Clock division change [hdiv:%x, pdiv:%x]\n”, hdivn, pdivn);
rCLKDIVN = (hdivn<<1) | pdivn;
switch(hdivn_val) {
case 16: // when 1, HCLK=FCLK/8.
rCAMDIVN = (rCAMDIVN & ~(3<<8)) | (1<<8);
break;
case 18: // when 1, HCLK=FCLK/6.
rCAMDIVN = (rCAMDIVN & ~(3<<8)) | (1<<9);
break;
}
if(hdivn!=0)
MMU_SetAsyncBusMode();
else
MMU_SetFastBusMode();
}
参阅数据手册：FIN=12000000 MDIV=92 PDIV=1 SDIV = 1 m=100,p=3,s=1, HSIVN=2 PDIVN =1 ,
依据MPLL的计算公式 2×100×1200000/（3×2）=400MHZ
HCLK=FCLK/4=100M
