/*********************************************************************
* init_clock_config - Clock Module *
**********************************************************************/
void init_clock_config(void)
{
/* Clock module uses normal PLL mode with 16.0000 MHz external reference
Bus clock frequency = 80.00 MHz
Processor clock frequency = 3 x bus clock = 240.00 MHz
Dithering disabled
*/
/* Check to see if the SDRAM has already been initialized
by a run control tool. If it has, put SDRAM into self-refresh mode before
initializing the PLL
*/
if (MCF_SDRAMC_SDCR & MCF_SDRAMC_SDCR_REF)
MCF_SDRAMC_SDCR &= ~MCF_SDRAMC_SDCR_CKE;
/* Temporarily switch to LIMP mode
NOTE: Ensure that this code is not executing from SDRAM, since the
SDRAM Controller is disabled in LIMP mode
*/
MCF_CCM_CDR = (MCF_CCM_CDR & 0xf0ff) | MCF_CCM_CDR_LPDIV(0x2);
MCF_CCM_MISCCR |= MCF_CCM_MISCCR_LIMP;
/* Configure the PLL settings */
MCF_PLL_PODR = MCF_PLL_PODR_CPUDIV(0x2) | MCF_PLL_PODR_BUSDIV(0x6);
MCF_PLL_PFDR = MCF_PLL_PFDR_MFD(0x78);
MCF_PLL_PLLCR = 0;
MCF_PLL_PMDR = 0;
/* Enable PLL and wait for lock */
MCF_CCM_MISCCR &= ~MCF_CCM_MISCCR_LIMP;
while ((MCF_CCM_MISCCR & MCF_CCM_MISCCR_PLL_LOCK) == 0) ;
/* From the Device Errata:
"After exiting LIMP mode, the value of 0x40000000 should be written
to address 0xFC0B8080 before attempting to initialize the SDRAMC
or exit the SDRAM from self-refresh mode."
*/
*(vuint32 *) 0xfc0b8080 = 0x40000000;
/* If we put the SDRAM into self-refresh mode earlier, restore mode now */
if (MCF_SDRAMC_SDCR & MCF_SDRAMC_SDCR_REF)
MCF_SDRAMC_SDCR |= MCF_SDRAMC_SDCR_CKE;
}
int clock_pll(int fsys, int flags)
{
int fref, temp, fout, mfd;
u32 i;
fref = FREF;
if (fsys == 0) {
/* Return current PLL output */
mfd = MCF_PLL_PFDR;
return (fref * mfd / (BUSDIV * 4));
}
/* Check bounds of requested system clock */
if (fsys > MAX_FSYS)
fsys = MAX_FSYS;
if (fsys < MIN_FSYS)
fsys = MIN_FSYS;
/* Multiplying by 100 when calculating the temp value,
and then dividing by 100 to calculate the mfd allows
for exact values without needing to include floating
point libraries. */
temp = 100 * fsys / fref;
mfd = 4 * BUSDIV * temp / 100;
/* Determine the output frequency for selected values */
fout = (fref * mfd / (BUSDIV * 4));
/*
* Check to see if the SDRAM has already been initialized.
* If it has then the SDRAM needs to be put into self refresh
* mode before reprogramming the PLL.
*/
if (MCF_SDRAMC_SDCR & MCF_SDRAMC_SDCR_REF)
/* Put SDRAM into self refresh mode */
MCF_SDRAMC_SDCR &= ~MCF_SDRAMC_SDCR_CKE;
/*
* Initialize the PLL to generate the new system clock frequency.
* The device must be put into LIMP mode to reprogram the PLL.
*/
/* Enter LIMP mode */
clock_limp(DEFAULT_LPD);
/* Reprogram PLL for desired fsys */
MCF_PLL_PODR = (0
| MCF_PLL_PODR_CPUDIV(BUSDIV/3)
| MCF_PLL_PODR_BUSDIV(BUSDIV));
MCF_PLL_PFDR = mfd;
/* Exit LIMP mode */
clock_exit_limp();
/*
* Return the SDRAM to normal operation if it is in use.
*/
if (MCF_SDRAMC_SDCR & MCF_SDRAMC_SDCR_REF)
/* Exit self refresh mode */
MCF_SDRAMC_SDCR |= MCF_SDRAMC_SDCR_CKE;
/* Errata - workaround for SDRAM opeartion after exiting LIMP mode */
MCF_SDRAMC_LIMP_FIX = MCF_SDRAMC_REFRESH;
/* wait for DQS logic to relock */
for (i = 0; i < 0x200; i++)
;
return fout;
}
