Import of the watch repository from Pebble

platform/robert/boot/src/drivers/pwr.c

@@ -0,0 +1,41 @@
+/*
+ * 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.
+ */
+
+#include "drivers/pwr.h"
+
+#include "drivers/periph_config.h"
+
+#include "stm32f7xx.h"
+
+void pwr_access_backup_domain(bool enable_access) {
+  periph_config_enable(PWR, RCC_APB1Periph_PWR);
+  if (enable_access) {
+    __atomic_or_fetch(&PWR->CR1, PWR_CR1_DBP, __ATOMIC_RELAXED);
+  } else {
+    __atomic_and_fetch(&PWR->CR1, ~PWR_CR1_DBP, __ATOMIC_RELAXED);
+  }
+  periph_config_disable(PWR, RCC_APB1Periph_PWR);
+}
+
+
+bool pwr_did_boot_from_standby(void) {
+  bool result = (PWR->CSR1 & PWR_CSR1_SBF) != 0;
+  return result;
+}
+
+void pwr_clear_boot_from_standby_flag(void) {
+  PWR->CR1 |= PWR_CR1_CSBF;
+}