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/**
* @file
*
* @ingroup mpc55xx
*
* @brief System clock calculation.
*/
/*
* Copyright (c) 2008-2011 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Obere Lagerstr. 30
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#include <bsp.h>
#include <bsp/start.h>
#include <bsp/mpc55xx-config.h>
uint32_t mpc55xx_get_system_clock(void)
{
uint32_t system_clock = 0;
#ifdef MPC55XX_HAS_FMPLL
volatile struct FMPLL_tag *fmpll = &FMPLL;
union FMPLL_SYNSR_tag synsr = { .R = fmpll->SYNSR.R };
uint32_t reference_clock = MPC55XX_FMPLL_REF_CLOCK;
bool pll_clock_mode = synsr.B.MODE != 0;
bool crystal_or_external_reference_mode = synsr.B.PLLSEL != 0;
if (pll_clock_mode) {
if (crystal_or_external_reference_mode) {
union FMPLL_SYNCR_tag syncr = { .R = fmpll->SYNCR.R };
uint32_t prediv = syncr.B.PREDIV;
uint32_t mfd = syncr.B.MFD;
uint32_t rfd = syncr.B.RFD;
system_clock = ((reference_clock * (mfd + 4)) >> rfd) / (prediv + 1);
} else {
system_clock = 2 * reference_clock;
}
} else {
system_clock = reference_clock;
}
#endif
#ifdef MPC55XX_HAS_FMPLL_ENHANCED
volatile struct FMPLL_tag *fmpll = &FMPLL;
union FMPLL_ESYNCR1_tag esyncr1 = { .R = fmpll->ESYNCR1.R };
uint32_t reference_clock = MPC55XX_FMPLL_REF_CLOCK;
bool normal_mode = (esyncr1.B.CLKCFG & 0x4U) != 0;
if (normal_mode) {
union FMPLL_ESYNCR2_tag esyncr2 = { .R = fmpll->ESYNCR2.R };
uint32_t eprediv = esyncr1.B.EPREDIV;
uint32_t emfd = esyncr1.B.EMFD;
uint32_t erfd = esyncr2.B.ERFD;
system_clock = (reference_clock * (emfd + 16))
/ ((erfd + 1) * (eprediv + 1));
} else {
system_clock = reference_clock;
}
#endif
#ifdef MPC55XX_HAS_MODE_CONTROL
/* FIXME: Assumes normal mode and external oscillator */
PLLD_CR_32B_tag cr = { . R = CGM.FMPLL [0].CR.R };
uint32_t xosc = MPC55XX_FMPLL_REF_CLOCK;
uint32_t ldf = cr.B.NDIV;
uint32_t idf = cr.B.IDF + 1;
uint32_t odf = 2U << cr.B.ODF;
system_clock = (xosc * ldf) / (idf * odf);
#endif
return system_clock;
}
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