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/*
*
* (C) Copyright 2000-2003
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* Copyright (C) 2004-2007 Freescale Semiconductor, Inc.
* TsiChung Liew (Tsi-Chung.Liew@freescale.com)
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <asm/processor.h>
#include <asm/immap.h>
DECLARE_GLOBAL_DATA_PTR;
/* PLL min/max specifications */
#define MAX_FVCO 500000 /* KHz */
#define MAX_FSYS 80000 /* KHz */
#define MIN_FSYS 58333 /* KHz */
#define FREF 16000 /* KHz */
#define MAX_MFD 135 /* Multiplier */
#define MIN_MFD 88 /* Multiplier */
#define BUSDIV 6 /* Divider */
/*
* Low Power Divider specifications
*/
#define MIN_LPD (1 << 0) /* Divider (not encoded) */
#define MAX_LPD (1 << 15) /* Divider (not encoded) */
#define DEFAULT_LPD (1 << 1) /* Divider (not encoded) */
/*
* Get the value of the current system clock
*
* Parameters:
* none
*
* Return Value:
* The current output system frequency
*/
int get_sys_clock(void)
{
volatile ccm_t *ccm = (volatile ccm_t *)(MMAP_CCM);
volatile pll_t *pll = (volatile pll_t *)(MMAP_PLL);
int divider;
/* Test to see if device is in LIMP mode */
if (ccm->misccr & CCM_MISCCR_LIMP) {
divider = ccm->cdr & CCM_CDR_LPDIV(0xF);
return (FREF / (2 << divider));
} else {
return ((FREF * pll->pfdr) / (BUSDIV * 4));
}
}
/*
* Initialize the Low Power Divider circuit
*
* Parameters:
* div Desired system frequency divider
*
* Return Value:
* The resulting output system frequency
*/
int clock_limp(int div)
{
volatile ccm_t *ccm = (volatile ccm_t *)(MMAP_CCM);
u32 temp;
/* Check bounds of divider */
if (div < MIN_LPD)
div = MIN_LPD;
if (div > MAX_LPD)
div = MAX_LPD;
/* Save of the current value of the SSIDIV so we don't overwrite the value */
temp = (ccm->cdr & CCM_CDR_SSIDIV(0xF));
/* Apply the divider to the system clock */
ccm->cdr = (CCM_CDR_LPDIV(div) | CCM_CDR_SSIDIV(temp));
ccm->misccr |= CCM_MISCCR_LIMP;
return (FREF / (3 * (1 << div)));
}
/*
* Exit low power LIMP mode
*
* Parameters:
* div Desired system frequency divider
*
* Return Value:
* The resulting output system frequency
*/
int clock_exit_limp(void)
{
volatile ccm_t *ccm = (volatile ccm_t *)(MMAP_CCM);
int fout;
/* Exit LIMP mode */
ccm->misccr &= (~CCM_MISCCR_LIMP);
/* Wait for PLL to lock */
while (!(ccm->misccr & CCM_MISCCR_PLL_LOCK)) ;
fout = get_sys_clock();
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;
}
/*
* get_clocks() fills in gd->cpu_clock and gd->bus_clk
*/
int get_clocks(void)
{
gd->bus_clk = clock_pll(CFG_CLK / 1000, 0) * 1000;
gd->cpu_clk = (gd->bus_clk * 3);
return (0);
}
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