mirror of https://github.com/ARMmbed/mbed-os.git
125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2017-2019 Arm Limited
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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");
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* you may 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,
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* WITHOUT 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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* Supports the High-resolution Ticker for mbed by implementing
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* \ref us_ticker_api.h, using a CMSDK Timer \ref timer_cmsdk_dev_t.
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*/
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#include "device.h"
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#include "mbed_critical.h"
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#include "timer_cmsdk_drv.h"
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#include "us_ticker_api.h"
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static uint64_t total_ticks = 0;
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/* Stores the last reload value, or the last tick value read when a read API
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* call occurs from the upper layer, needed to keep total_ticks
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* accumulated properly.
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*/
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static uint32_t previous_ticks = 0;
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static void restart_timer(uint32_t new_reload)
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{
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timer_cmsdk_disable(&USEC_TIMER_DEV);
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timer_cmsdk_set_reload_value(&USEC_TIMER_DEV,
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new_reload);
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timer_cmsdk_reset(&USEC_TIMER_DEV);
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timer_cmsdk_clear_interrupt(&USEC_TIMER_DEV);
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timer_cmsdk_enable_interrupt(&USEC_TIMER_DEV);
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timer_cmsdk_enable(&USEC_TIMER_DEV);
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}
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static void update_ticker(void)
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{
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if (timer_cmsdk_is_interrupt_active(&USEC_TIMER_DEV)) {
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total_ticks += previous_ticks;
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previous_ticks = TIMER_CMSDK_MAX_RELOAD;
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restart_timer(previous_ticks);
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} else {
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uint32_t tick = timer_cmsdk_get_current_value(&USEC_TIMER_DEV);
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if (tick < previous_ticks) {
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uint32_t delta = previous_ticks - tick;
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total_ticks += delta;
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previous_ticks = tick;
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}
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}
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}
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void us_ticker_init(void)
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{
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timer_cmsdk_init(&USEC_TIMER_DEV);
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previous_ticks = TIMER_CMSDK_MAX_RELOAD;
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NVIC_EnableIRQ(USEC_INTERVAL_IRQ);
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restart_timer(previous_ticks);
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}
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void us_ticker_free(void)
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{
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timer_cmsdk_disable(&USEC_TIMER_DEV);
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}
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uint32_t us_ticker_read(void)
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{
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core_util_critical_section_enter();
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update_ticker();
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core_util_critical_section_exit();
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return (uint32_t)(total_ticks >> USEC_REPORTED_SHIFT);
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}
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void us_ticker_set_interrupt(timestamp_t timestamp)
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{
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uint32_t reload = (timestamp - us_ticker_read()) << USEC_REPORTED_SHIFT;
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previous_ticks = reload;
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restart_timer(previous_ticks);
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}
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void us_ticker_disable_interrupt(void)
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{
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timer_cmsdk_disable_interrupt(&USEC_TIMER_DEV);
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}
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void us_ticker_clear_interrupt(void)
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{
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timer_cmsdk_clear_interrupt(&USEC_TIMER_DEV);
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}
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void us_ticker_fire_interrupt(void)
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{
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NVIC_SetPendingIRQ(USEC_INTERVAL_IRQ);
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}
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const ticker_info_t* us_ticker_get_info()
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{
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static const ticker_info_t info = {
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USEC_REPORTED_FREQ_HZ,
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USEC_REPORTED_BITS
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};
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return &info;
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}
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#ifndef usec_interval_irq_handler
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#error "usec_interval_irq_handler should be defined, check device_cfg.h!"
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#endif
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void usec_interval_irq_handler(void)
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{
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update_ticker();
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us_ticker_irq_handler();
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}
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