STM32_RTC_CR_OSEL
cr &= ~STM32_RTC_CR_OSEL;
unsigned int tampalrm = STM32_RTC_CR_TAMPOE | STM32_RTC_CR_OSEL;
#define STM32_RTC_CR_OSEL_ALARM_A FIELD_PREP(STM32_RTC_CR_OSEL, 0x01)