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Diffstat (limited to 'cpu/mcf532x/speed.c')
| -rw-r--r-- | cpu/mcf532x/speed.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/cpu/mcf532x/speed.c b/cpu/mcf532x/speed.c new file mode 100644 index 0000000..001b9f4 --- /dev/null +++ b/cpu/mcf532x/speed.c @@ -0,0 +1,216 @@ +/* + * + * (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); +} |