mirror of https://github.com/ARMmbed/mbed-os.git
132 lines
3.7 KiB
C
132 lines
3.7 KiB
C
/***************************************************************************//**
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* @file us_ticker.c
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*******************************************************************************
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* @section License
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* <b>(C) Copyright 2016 Silicon Labs, http://www.silabs.com</b>
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*******************************************************************************
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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#include <stddef.h>
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#include "us_ticker_api.h"
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#include "device.h"
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#include "mbed_assert.h"
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#include "em_cmu.h"
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#include "em_timer.h"
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#include "clocking.h"
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#define TICKER_FREQUENCY ((REFERENCE_FREQUENCY > 24000000) ? REFERENCE_FREQUENCY / 16 : REFERENCE_FREQUENCY / 8)
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const ticker_info_t* us_ticker_get_info(void)
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{
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static const ticker_info_t info = {
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TICKER_FREQUENCY,
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16
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};
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return &info;
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}
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static bool us_ticker_inited = false; // Is ticker initialized yet
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void us_ticker_init(void)
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{
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if (us_ticker_inited) {
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/* calling init again should cancel current interrupt */
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us_ticker_disable_interrupt();
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return;
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}
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us_ticker_inited = true;
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/* Enable clock for TIMERs */
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CMU_ClockEnable(US_TICKER_TIMER_CLOCK, true);
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if (REFERENCE_FREQUENCY > 24000000) {
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US_TICKER_TIMER->CTRL = (US_TICKER_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (4 << _TIMER_CTRL_PRESC_SHIFT);
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} else {
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US_TICKER_TIMER->CTRL = (US_TICKER_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (3 << _TIMER_CTRL_PRESC_SHIFT);
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}
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/* Clear TIMER counter value */
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TIMER_CounterSet(US_TICKER_TIMER, 0);
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/* Start TIMER */
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TIMER_Enable(US_TICKER_TIMER, true);
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/* Select Compare Channel parameters */
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TIMER_InitCC_TypeDef timerCCInit = TIMER_INITCC_DEFAULT;
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timerCCInit.mode = timerCCModeCompare;
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/* Configure Compare Channel 0 */
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TIMER_InitCC(US_TICKER_TIMER, 0, &timerCCInit);
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/* Enable interrupt vector in NVIC */
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TIMER_IntClear(US_TICKER_TIMER, TIMER_IEN_CC0);
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NVIC_SetVector(US_TICKER_TIMER_IRQ, (uint32_t) us_ticker_irq_handler);
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NVIC_EnableIRQ(US_TICKER_TIMER_IRQ);
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}
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void us_ticker_free(void)
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{
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if (us_ticker_inited) {
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us_ticker_disable_interrupt();
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NVIC_DisableIRQ(US_TICKER_TIMER_IRQ);
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TIMER_Enable(US_TICKER_TIMER, false);
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CMU_ClockEnable(US_TICKER_TIMER_CLOCK, false);
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us_ticker_inited = false;
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}
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}
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uint32_t us_ticker_read()
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{
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if (!us_ticker_inited) {
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us_ticker_init();
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}
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return US_TICKER_TIMER->CNT;
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}
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void us_ticker_set_interrupt(timestamp_t timestamp)
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{
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TIMER_IntDisable(US_TICKER_TIMER, TIMER_IEN_CC0);
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TIMER_IntClear(US_TICKER_TIMER, TIMER_IEN_CC0);
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TIMER_CompareSet(US_TICKER_TIMER, 0, timestamp);
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TIMER_IntEnable(US_TICKER_TIMER, TIMER_IEN_CC0);
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}
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void us_ticker_fire_interrupt(void)
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{
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NVIC_SetPendingIRQ(US_TICKER_TIMER_IRQ);
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}
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void us_ticker_disable_interrupt(void)
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{
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/* Disable compare channel interrupts */
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TIMER_IntDisable(US_TICKER_TIMER, TIMER_IEN_CC0);
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}
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void us_ticker_clear_interrupt(void)
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{
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/* Clear compare channel interrupts */
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TIMER_IntClear(US_TICKER_TIMER, TIMER_IFC_CC0);
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}
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