Import of the watch repository from Pebble

src/fw/drivers/clocksource.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+//! Configure and start the 32 kHz LSE clock.
+void clocksource_lse_configure(void);
+
+//! Returns true iff LSE is running.
+bool clocksource_is_lse_started(void);
+
+//! Enable or disable 32 kHz clock output on pin MCO1.
+//!
+//! Prerequisite: clocksource_lse_configure() must be called beforehand to
+//! enable the 32 kHz clock.
+void clocksource_MCO1_enable(bool on);