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;
}
/* Initialize the PLL
*
* Parameters:
* fref PLL reference clock frequency in KHz
* fsys Desired PLL output frequency in KHz
* flags Operating parameters
*
* Return Value:
* The resulting output system frequency
*/
int clock_pll(int fsys, int flags)
{
volatile u32 *sdram_workaround = (volatile u32 *)(MMAP_SDRAM + 0x80);
volatile pll_t *pll = (volatile pll_t *)(MMAP_PLL);
int fref, temp, fout, mfd;
u32 i;
fref = FREF;
if (fsys == 0) {
/* Return current PLL output */
mfd = 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.
*/
/*
* 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 */
pll->podr = (PLL_PODR_CPUDIV(BUSDIV / 3) | PLL_PODR_BUSDIV(BUSDIV));
pll->pfdr = mfd;
/* Exit LIMP mode */
clock_exit_limp();
/*
* Return the SDRAM to normal operation if it is in use.
*/
/* software workaround for SDRAM opeartion after exiting LIMP mode errata */
*sdram_workaround = CFG_SDRAM_BASE;
/* wait for DQS logic to relock */
for (i = 0; i < 0x200; i++) ;
return fout;
}
