*/rtt|rtc: Fix Kconfig modeling

boards/common/nucleo/Kconfig

@@ -15,3 +15,5 @@ config MODULE_BOARDS_COMMON_NUCLEO
         stm32 common nucleo code.
 
 endif # TEST_KCONFIG
+
+rsource "../stm32/Kconfig"

cpu/stm32/Kconfig

@@ -16,6 +16,9 @@ config CPU_STM32
     select HAS_PERIPH_UART_MODECFG
     select HAS_PERIPH_UART_NONBLOCKING
 
+    # This CPU requires periph_rtc when periph_rtc_mem
+    select MODULE_PERIPH_RTC if MODULE_PERIPH_RTC_MEM && HAS_PERIPH_RTC
+
 # Common CPU symbol
 config CPU
     default "stm32" if CPU_STM32

drivers/periph_common/Kconfig

@@ -126,6 +126,11 @@ config MODULE_PERIPH_RTT_SET_COUNTER
     bool "rtc_set_counter() implementation in the RTT peripheral driver"
     depends on HAS_PERIPH_RTT_SET_COUNTER && MODULE_PERIPH_RTT
 
+config MODULE_PERIPH_INIT_RTT_SET_COUNTER
+    bool "Auto initialize rtc_set_counter() with RTT"
+    default y if MODULE_PERIPH_INIT
+    depends on MODULE_PERIPH_RTT_SET_COUNTER
+
 config MODULE_PERIPH_INIT_RTT
     bool "Auto initialize RTT peripheral"
     default y if MODULE_PERIPH_INIT

drivers/periph_common/Kconfig.rtc

@@ -15,5 +15,21 @@ config MODULE_PERIPH_INIT_RTC
     default y if MODULE_PERIPH_INIT
     depends on MODULE_PERIPH_RTC
 
+config MODULE_PERIPH_RTC_MEM
+    bool "Low-Power RTC Memory"
+    depends on HAS_PERIPH_RTC_MEM
+    help
+        Provides an interface to access low-power memory present on some RTCs.
+        This memory is retained even when the rest of the system is powered off.
+
+# TODO: this module is actually just an artifact from the way periph_init_%
+# modules are handled in Makefile. We need to define it to keep the list the
+# same for now. We should be able to remove it later on.
+
+config MODULE_PERIPH_INIT_RTC_MEM
+    bool
+    default y if MODULE_PERIPH_INIT
+    depends on MODULE_PERIPH_RTC_MEM
+
 # Include CPU specific configurations
 osource "$(RIOTCPU)/$(CPU)/periph/Kconfig.rtc"

sys/ztimer/Kconfig

@@ -76,8 +76,7 @@ choice
     depends on MODULE_ZTIMER_SEC
     default ZTIMER_SEC_BACKEND_RTC if !BOARD_NATIVE && \
                                       !CPU_COMMON_SAM0 && \
-                                      !CPU_COMMON_EFM32 && \
+                                      !CPU_COMMON_EFM32
-                                      !CPU_FAM_F1
     default ZTIMER_SEC_BACKEND_RTT
 
 config ZTIMER_SEC_BACKEND_TIMER

tests/periph_rtc/Kconfig

@@ -0,0 +1,11 @@
+# Copyright (c) 2021 HAW Hamburg
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+
+config APPLICATION
+    bool
+    default y
+    imply MODULE_PERIPH_RTC_MEM

tests/periph_rtc/Makefile

@@ -8,4 +8,7 @@ DISABLE_MODULE += periph_init_rtc
 
 USEMODULE += xtimer
 
+# avoid running Kconfig by default
+SHOULD_RUN_KCONFIG ?=
+
 include $(RIOTBASE)/Makefile.include

tests/periph_rtt/Kconfig

@@ -9,4 +9,5 @@ config APPLICATION
     bool
     default y
     imply MODULE_PERIPH_RTT_SET_COUNTER
+    imply MODULE_PERIPH_RTC_MEM
     depends on TEST_KCONFIG

tests/periph_rtt/Makefile

@@ -7,6 +7,9 @@ FEATURES_OPTIONAL += periph_rtc_mem
 
 DISABLE_MODULE += periph_init_rtt
 
+# avoid running Kconfig by default
+SHOULD_RUN_KCONFIG ?=
+
 include $(RIOTBASE)/Makefile.include
 
 # Put board specific dependencies here