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// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include "pw_sync/interrupt_spin_lock.h"
#include "pw_assert/check.h"
#include "pw_interrupt/context.h"
#include "task.h"
namespace pw::sync {
#if (INCLUDE_xTaskGetSchedulerState != 1) && (configUSE_TIMERS != 1)
#error "xTaskGetSchedulerState is required for pw::sync::InterruptSpinLock"
#endif
void InterruptSpinLock::lock() {
if (interrupt::InInterruptContext()) {
native_type_.saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
} else { // Task context
// Suspending the scheduler ensures that kernel API calls that occur
// within the critical section will not preempt the current task
// (if called from a thread context). Otherwise, kernel APIs called
// from within the critical section may preempt the running task if
// the port implements portYIELD synchronously.
// Note: calls to vTaskSuspendAll(), like taskENTER_CRITICAL() can
// be nested.
// Note: vTaskSuspendAll()/xTaskResumeAll() are not safe to call before the
// scheduler has been started.
if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED) {
vTaskSuspendAll();
}
taskENTER_CRITICAL();
}
// We can't deadlock here so crash instead.
PW_DCHECK(!native_type_.locked,
"Recursive InterruptSpinLock::lock() detected");
native_type_.locked = true;
}
void InterruptSpinLock::unlock() {
native_type_.locked = false;
if (interrupt::InInterruptContext()) {
taskEXIT_CRITICAL_FROM_ISR(native_type_.saved_interrupt_mask);
} else { // Task context
taskEXIT_CRITICAL();
if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED) {
xTaskResumeAll();
}
}
}
} // namespace pw::sync
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