64 lines
2.2 KiB
C++
64 lines
2.2 KiB
C++
// Copyright 2020 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://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. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_sync/interrupt_spin_lock.h"
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#include "pw_assert/check.h"
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#include "pw_interrupt/context.h"
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#include "task.h"
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namespace pw::sync {
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#if (INCLUDE_xTaskGetSchedulerState != 1) && (configUSE_TIMERS != 1)
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#error "xTaskGetSchedulerState is required for pw::sync::InterruptSpinLock"
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#endif
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void InterruptSpinLock::lock() {
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if (interrupt::InInterruptContext()) {
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native_type_.saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
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} else { // Task context
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// Suspending the scheduler ensures that kernel API calls that occur
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// within the critical section will not preempt the current task
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// (if called from a thread context). Otherwise, kernel APIs called
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// from within the critical section may preempt the running task if
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// the port implements portYIELD synchronously.
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// Note: calls to vTaskSuspendAll(), like taskENTER_CRITICAL() can
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// be nested.
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// Note: vTaskSuspendAll()/xTaskResumeAll() are not safe to call before the
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// scheduler has been started.
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if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED) {
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vTaskSuspendAll();
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}
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taskENTER_CRITICAL();
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}
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// We can't deadlock here so crash instead.
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PW_DCHECK(!native_type_.locked,
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"Recursive InterruptSpinLock::lock() detected");
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native_type_.locked = true;
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}
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void InterruptSpinLock::unlock() {
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native_type_.locked = false;
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if (interrupt::InInterruptContext()) {
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taskEXIT_CRITICAL_FROM_ISR(native_type_.saved_interrupt_mask);
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} else { // Task context
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taskEXIT_CRITICAL();
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if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED) {
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xTaskResumeAll();
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}
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}
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}
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} // namespace pw::sync
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