forked from Imagelibrary/rtems
134 lines
3.7 KiB
C
134 lines
3.7 KiB
C
/* SPDX-License-Identifier: BSD-2-Clause */
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/**
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* @file
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*
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* @ingroup RTEMSBSPsARMLPC176X_clocks
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*
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* @brief System clocks.
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*/
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/*
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* Copyright (c) 2008-2012 embedded brains GmbH. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <bsp.h>
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#include <bsp/system-clocks.h>
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/**
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* @brief Internal RC oscillator frequency in [Hz].
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*/
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#define LPC176X_OSCILLATOR_INTERNAL 4000000u
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#ifndef LPC176X_OSCILLATOR_MAIN
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#error "unknown main oscillator frequency"
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#endif
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#ifndef LPC176X_OSCILLATOR_RTC
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#error "unknown RTC oscillator frequency"
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#endif
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inline unsigned lpc176x_sysclk( void );
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void lpc176x_timer_initialize( void )
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{
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/* Reset timer */
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LPC176X_T1TCR = TCR_RST;
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/* Set timer mode */
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LPC176X_T1CTCR = 0u;
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/* Set prescaler to zero */
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LPC176X_T1PR = 0u;
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/* Reset all interrupt flags */
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LPC176X_T1IR = 0xffU;
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/* Do not stop on a match */
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LPC176X_T1MCR = 0u;
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/* No captures */
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LPC176X_T1CCR = 0u;
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/* Start timer */
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LPC176X_T1TCR = TCR_EN;
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}
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void lpc176x_micro_seconds_delay( const unsigned us )
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{
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const unsigned start = lpc176x_get_timer1();
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const unsigned delay = us * ( LPC176X_PCLK / 1000000u );
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unsigned elapsed = 0u;
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do {
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elapsed = lpc176x_get_timer1() - start;
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} while ( elapsed < delay );
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}
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unsigned lpc176x_sysclk( void )
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{
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return ( LPC176X_SCB.clksrcsel & LPC176X_SCB_CLKSRCSEL_CLKSRC ) != 0u ?
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LPC176X_OSCILLATOR_MAIN : LPC176X_OSCILLATOR_INTERNAL;
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}
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unsigned lpc176x_pllclk( void )
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{
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const unsigned sysclk = lpc176x_sysclk();
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const unsigned pllstat = ( LPC176X_SCB.pll_0 ).stat;
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const unsigned enabled_and_locked = LPC176X_PLL_STAT_PLLE |
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LPC176X_PLL_STAT_PLOCK;
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unsigned pllclk = 0u;
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if ( ( pllstat & enabled_and_locked ) == enabled_and_locked ) {
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unsigned m = LPC176X_PLL_SEL_MSEL_GET( pllstat ) + 1u;
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pllclk = sysclk * m;
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}
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/* else implies that the pllstat is unlocked. Also,
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there is nothing to do. */
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return pllclk;
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}
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unsigned lpc176x_cclk( void )
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{
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const unsigned cclksel = LPC176X_SCB.cclksel;
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unsigned cclk_in = 0u;
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unsigned cclk = 0u;
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if ( ( cclksel & LPC176X_SCB_CCLKSEL_CCLKSEL ) != 0u ) {
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cclk_in = lpc176x_pllclk();
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} else {
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cclk_in = lpc176x_sysclk();
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}
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cclk = cclk_in / LPC176X_SCB_CCLKSEL_CCLKDIV_GET( cclksel );
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return cclk;
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}
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uint32_t _CPU_Counter_frequency(void)
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{
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return LPC176X_PCLK;
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}
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CPU_Counter_ticks _CPU_Counter_read( void )
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{
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return lpc176x_get_timer1();
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}
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