drivers: rtc: stm32: handle STM32WB0 series when RTC_ALARM is enabled

RTC alarm is not supported by the driver for now due to the complexity it
would take to work around an hardware erratum. However, it is not possible
to prevent CONFIG_RTC_ALARM from being enabled at Kconfig level.
Modify the RTC driver such that enabling CONFIG_RTC_ALARM on STM32WB0
series does not cause build errors anymore.

Signed-off-by: Mathieu Choplain <mathieu.choplain@st.com>

drivers/rtc/rtc_ll_stm32.c

@@ -78,7 +78,7 @@ LOG_MODULE_REGISTER(rtc_stm32, CONFIG_RTC_LOG_LEVEL);
 /* Timeout in microseconds used to wait for flags */
 #define RTC_TIMEOUT 1000000
 
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 #define RTC_STM32_ALARMS_COUNT	DT_INST_PROP(0, alarms_count)
 
 #define RTC_STM32_ALRM_A	0U
@@ -95,7 +95,7 @@ LOG_MODULE_REGISTER(rtc_stm32, CONFIG_RTC_LOG_LEVEL);
 #else
 #define RTC_STM32_EXTI_LINE	0
 #endif /* DT_INST_NODE_HAS_PROP(0, alrm_exti_line) */
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 
 #if defined(PWR_CR_DBP) || defined(PWR_CR1_DBP) || defined(PWR_DBPCR_DBP) || defined(PWR_DBPR_DBP)
 /*
@@ -120,7 +120,7 @@ struct rtc_stm32_config {
 #endif
 };
 
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 struct rtc_stm32_alrm {
 	LL_RTC_AlarmTypeDef ll_rtc_alrm;
 	/* user-defined alarm mask, values from RTC_ALARM_TIME_MASK */
@@ -129,14 +129,14 @@ struct rtc_stm32_alrm {
 	void *user_data;
 	bool is_pending;
 };
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 
 struct rtc_stm32_data {
 	struct k_mutex lock;
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 	struct rtc_stm32_alrm rtc_alrm_a;
 	struct rtc_stm32_alrm rtc_alrm_b;
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 };
 
 static int rtc_stm32_configure(const struct device *dev)
@@ -185,7 +185,7 @@ static int rtc_stm32_configure(const struct device *dev)
 	return err;
 }
 
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 static inline ErrorStatus rtc_stm32_init_alarm(RTC_TypeDef *rtc, uint32_t format,
 					LL_RTC_AlarmTypeDef *ll_alarm_struct, uint16_t id)
 {
@@ -329,7 +329,7 @@ static void rtc_stm32_irq_config(const struct device *dev)
 		    rtc_stm32_isr, DEVICE_DT_INST_GET(0), 0);
 	irq_enable(DT_INST_IRQN(0));
 }
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 
 static int rtc_stm32_init(const struct device *dev)
 {
@@ -421,7 +421,7 @@ static int rtc_stm32_init(const struct device *dev)
 	LL_PWR_DisableBkUpAccess();
 #endif /* RTC_STM32_BACKUP_DOMAIN_WRITE_PROTECTION */
 
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 	rtc_stm32_irq_config(dev);
 
 	ll_func_exti_enable_rtc_alarm_it(RTC_STM32_EXTI_LINE);
@@ -430,7 +430,7 @@ static int rtc_stm32_init(const struct device *dev)
 	memset(&(data->rtc_alrm_a), 0, sizeof(struct rtc_stm32_alrm));
 	memset(&(data->rtc_alrm_b), 0, sizeof(struct rtc_stm32_alrm));
 	k_mutex_unlock(&data->lock);
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 
 	return err;
 }
@@ -600,7 +600,7 @@ static int rtc_stm32_get_time(const struct device *dev, struct rtc_time *timeptr
 	return 0;
 }
 
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 static void rtc_stm32_init_ll_alrm_struct(LL_RTC_AlarmTypeDef *p_rtc_alarm,
 					const struct rtc_time *timeptr, uint16_t mask)
 {
@@ -995,7 +995,7 @@ unlock:
 	k_mutex_unlock(&data->lock);
 	return ret;
 }
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 
 #ifdef CONFIG_RTC_CALIBRATION
 #if !defined(CONFIG_SOC_SERIES_STM32F2X) && \
@@ -1078,13 +1078,13 @@ static int rtc_stm32_get_calibration(const struct device *dev, int32_t *calibrat
 static DEVICE_API(rtc, rtc_stm32_driver_api) = {
 	.set_time = rtc_stm32_set_time,
 	.get_time = rtc_stm32_get_time,
-#ifdef CONFIG_RTC_ALARM
+#ifdef STM32_RTC_ALARM_ENABLED
 	.alarm_get_supported_fields = rtc_stm32_alarm_get_supported_fields,
 	.alarm_set_time = rtc_stm32_alarm_set_time,
 	.alarm_get_time = rtc_stm32_alarm_get_time,
 	.alarm_set_callback = rtc_stm32_alarm_set_callback,
 	.alarm_is_pending = rtc_stm32_alarm_is_pending,
-#endif /* CONFIG_RTC_ALARM */
+#endif /* STM32_RTC_ALARM_ENABLED */
 #ifdef CONFIG_RTC_CALIBRATION
 #if !defined(CONFIG_SOC_SERIES_STM32F2X) && \
 	!(defined(CONFIG_SOC_SERIES_STM32L1X) && !defined(RTC_SMOOTHCALIB_SUPPORT))

drivers/rtc/rtc_ll_stm32.h

@@ -7,7 +7,23 @@
 #ifndef ZEPHYR_DRIVERS_RTC_RTC_LL_STM32_H_
 #define ZEPHYR_DRIVERS_RTC_RTC_LL_STM32_H_
 
-#ifdef CONFIG_RTC_ALARM
+/**
+ * ES0584 / ES0631 §2.5.2; ES0632 §2.6.2 (both Rev. 2)
+ * """
+ * RTC interrupts cannot be reliably used for real-time
+ * control functions, since some occurences of RTC
+ * interrupts may be missed.
+ * """
+ * Since alarm IRQs are unreliable, don't allow RTC alarm
+ * to be used on STM32WB0 series. For this, we have to
+ * create a #define only valid when both the Kconfig is
+ * enabled, and we're on a supported series. This must
+ * be done because the RTC driver has to build properly
+ * on all targets regardless of which Kconfig options have
+ * been enabled.
+ */
+#if defined(CONFIG_RTC_ALARM) && !defined(CONFIG_SOC_SERIES_STM32WB0X)
+#define STM32_RTC_ALARM_ENABLED	1
 
 /* STM32 RTC alarms, A & B, LL masks are equal */
 #define RTC_STM32_ALRM_MASK_ALL		LL_RTC_ALMA_MASK_ALL
@@ -44,6 +60,6 @@ static inline void ll_func_exti_clear_rtc_alarm_flag(uint32_t exti_line)
 	LL_EXTI_ClearFlag_0_31(exti_line);
 #endif /* CONFIG_SOC_SERIES_STM32H7X and CONFIG_CPU_CORTEX_M4 */
 }
-#endif /* CONFIG_RTC_ALARM */
+#endif /* CONFIG_RTC_ALARM && !CONFIG_SOC_SERIES_STM32WB0X */
 
 #endif	/* ZEPHYR_DRIVERS_RTC_RTC_LL_STM32_H_ */