forked from Imagelibrary/rtems
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/**
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* @file
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*
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* @ingroup RTEMSBSPsPowerPCMPC55XX
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*
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* @brief System clock calculation.
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*/
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/*
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* Copyright (c) 2008-2011 embedded brains GmbH. All rights reserved.
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*
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* embedded brains GmbH
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* Obere Lagerstr. 30
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* 82178 Puchheim
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* Germany
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* <rtems@embedded-brains.de>
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rtems.org/license/LICENSE.
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*/
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#include <bsp.h>
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#include <bsp/start.h>
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#include <bsp/mpc55xx-config.h>
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uint32_t mpc55xx_get_system_clock(void)
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{
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uint32_t system_clock = 0;
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#ifdef MPC55XX_HAS_FMPLL
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volatile struct FMPLL_tag *fmpll = &FMPLL;
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union FMPLL_SYNSR_tag synsr = { .R = fmpll->SYNSR.R };
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uint32_t reference_clock = MPC55XX_REFERENCE_CLOCK;
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bool pll_clock_mode = synsr.B.MODE != 0;
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bool crystal_or_external_reference_mode = synsr.B.PLLSEL != 0;
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if (pll_clock_mode) {
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if (crystal_or_external_reference_mode) {
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union FMPLL_SYNCR_tag syncr = { .R = fmpll->SYNCR.R };
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uint32_t prediv = syncr.B.PREDIV;
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uint32_t mfd = syncr.B.MFD;
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uint32_t rfd = syncr.B.RFD;
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system_clock = ((reference_clock * (mfd + 4)) >> rfd) / (prediv + 1);
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} else {
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system_clock = 2 * reference_clock;
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}
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} else {
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system_clock = reference_clock;
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}
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#endif
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#ifdef MPC55XX_HAS_FMPLL_ENHANCED
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volatile struct FMPLL_tag *fmpll = &FMPLL;
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union FMPLL_ESYNCR1_tag esyncr1 = { .R = fmpll->ESYNCR1.R };
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uint32_t reference_clock = MPC55XX_REFERENCE_CLOCK;
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bool normal_mode = (esyncr1.B.CLKCFG & 0x4U) != 0;
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if (normal_mode) {
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union FMPLL_ESYNCR2_tag esyncr2 = { .R = fmpll->ESYNCR2.R };
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uint32_t eprediv = esyncr1.B.EPREDIV;
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uint32_t emfd = esyncr1.B.EMFD;
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uint32_t erfd = esyncr2.B.ERFD;
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system_clock = ((reference_clock / (eprediv + 1)) * (emfd + 16))
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/ (erfd + 1);
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} else {
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system_clock = reference_clock;
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}
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#endif
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#ifdef MPC55XX_HAS_MODE_CONTROL
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/* FIXME: Assumes normal mode and external oscillator */
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PLLD_CR_32B_tag cr = { . R = CGM.FMPLL [0].CR.R };
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uint32_t xosc = MPC55XX_REFERENCE_CLOCK;
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uint32_t ldf = cr.B.NDIV;
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uint32_t idf = cr.B.IDF + 1;
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uint32_t odf = 2U << cr.B.ODF;
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system_clock = (xosc * ldf) / (idf * odf);
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#endif
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return system_clock;
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}
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