mirror of https://github.com/ARMmbed/mbed-os.git
97 lines
2.8 KiB
C++
97 lines
2.8 KiB
C++
/*
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* Copyright (c) 2016-2018 ARM Limited. All rights reserved.
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* SPDX-License-Identifier: Apache-2.0
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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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// Include before mbed.h to properly get UINT*_C()
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#include "ns_types.h"
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#include "mbed.h"
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#include "platform/SingletonPtr.h"
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#include "platform/arm_hal_timer.h"
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#include "platform/arm_hal_interrupt.h"
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#include <mbed_assert.h>
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static SingletonPtr<Timer> timer;
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static SingletonPtr<Timeout> timeout;
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// If critical sections are implemented using mutexes, timers must be called in thread context, and
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// we use the high-priority event queue for this.
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// If critical sections disable interrupts, we can call timers directly from interrupt. Avoiding the
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// event queue can save ~1600B of RAM if the rest of the system is not using the event queue either.
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// Caveats of this tunable are listed on arm_hal_interrupt.c.
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#if !MBED_CONF_NANOSTACK_HAL_CRITICAL_SECTION_USABLE_FROM_INTERRUPT
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static EventQueue *equeue;
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#endif
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static uint32_t due;
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static void (*arm_hal_callback)(void);
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// Called once at boot
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void platform_timer_enable(void)
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{
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#if !MBED_CONF_NANOSTACK_HAL_CRITICAL_SECTION_USABLE_FROM_INTERRUPT
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equeue = mbed_highprio_event_queue();
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MBED_ASSERT(equeue != NULL);
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#endif
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// Prime the SingletonPtrs - can't construct from IRQ/critical section
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timer.get();
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timeout.get();
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}
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// Actually cancels a timer, not the opposite of enable
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void platform_timer_disable(void)
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{
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timeout->detach();
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}
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// Not called while running, fortunately
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void platform_timer_set_cb(void (*new_fp)(void))
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{
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arm_hal_callback = new_fp;
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}
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static void timer_callback(void)
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{
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due = 0;
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#if MBED_CONF_NANOSTACK_HAL_CRITICAL_SECTION_USABLE_FROM_INTERRUPT
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// Callback is interrupt safe so it can be called directly without
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// bouncing via event queue thread.
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arm_hal_callback();
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#else
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equeue->call(arm_hal_callback);
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#endif
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}
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// This is called from inside platform_enter_critical - IRQs can't happen
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void platform_timer_start(uint16_t slots)
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{
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timer->reset();
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due = slots * UINT32_C(50);
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timeout->attach_us(timer_callback, due);
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}
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// This is called from inside platform_enter_critical - IRQs can't happen
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uint16_t platform_timer_get_remaining_slots(void)
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{
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uint32_t elapsed = timer->read_us();
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if (elapsed < due) {
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return (uint16_t) ((due - elapsed) / 50);
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} else {
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return 0;
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}
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}
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