pw_{sync,chrono}_freertos: Add initial FreeRTOS support
Adds initial FreeRTOS support through a set of backends for
pw_sync through pw_sync_freertos and pw_chrono through
pw_chrono_freertos.
Change-Id: I2c57482fbdac6993f2ccf756870fe6e2f138a62a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/24422
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>
diff --git a/pw_sync_freertos/spin_lock.cc b/pw_sync_freertos/spin_lock.cc
new file mode 100644
index 0000000..b7898f8
--- /dev/null
+++ b/pw_sync_freertos/spin_lock.cc
@@ -0,0 +1,65 @@
+// 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/spin_lock.h"
+
+#include "pw_assert/assert.h"
+#include "pw_interrupt/context.h"
+#include "task.h"
+
+namespace pw::sync {
+
+void SpinLock::lock() {
+ if (interrupt::InInterruptContext()) {
+ native_type_.saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
+ } else { // Task context
+ taskENTER_CRITICAL();
+ }
+ // We can't deadlock here so crash instead.
+ PW_CHECK(!native_type_.locked.load(std::memory_order_relaxed),
+ "Recursive SpinLock::lock() detected");
+ native_type_.locked.store(true, std::memory_order_relaxed);
+}
+
+bool SpinLock::try_lock() {
+ if (interrupt::InInterruptContext()) {
+ UBaseType_t saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
+ if (native_type_.locked.load(std::memory_order_relaxed)) {
+ // Already locked, restore interrupts and bail out.
+ taskEXIT_CRITICAL_FROM_ISR(saved_interrupt_mask);
+ return false;
+ }
+ native_type_.saved_interrupt_mask = saved_interrupt_mask;
+ } else { // Task context
+ taskENTER_CRITICAL();
+ if (native_type_.locked.load(std::memory_order_relaxed)) {
+ // ALready locked, restore interrupts and bail out.
+ taskEXIT_CRITICAL();
+ return false;
+ }
+ }
+ native_type_.locked.store(true, std::memory_order_relaxed);
+ return true;
+}
+
+void SpinLock::unlock() {
+ native_type_.locked.store(false, std::memory_order_relaxed);
+ if (interrupt::InInterruptContext()) {
+ taskEXIT_CRITICAL_FROM_ISR(native_type_.saved_interrupt_mask);
+ } else { // Task context
+ taskEXIT_CRITICAL();
+ }
+}
+
+} // namespace pw::sync