chore: add CMake support

Signed-off-by: Aymane Bahssain <aymane.bahssain@st.com>

Author: Aymane-ST

CMakeLists.txt

@@ -0,0 +1,31 @@
+# v3.21 implemented semantic changes regarding $<TARGET_OBJECTS:...>
+# See https://cmake.org/cmake/help/v3.21/command/target_link_libraries.html#linking-object-libraries-via-target-objects
+cmake_minimum_required(VERSION 3.21)
+
+add_library(STM32RTC INTERFACE)
+add_library(STM32RTC_usage INTERFACE)
+
+target_include_directories(STM32RTC_usage INTERFACE
+  src
+)
+
+
+target_link_libraries(STM32RTC_usage INTERFACE
+  base_config
+)
+
+target_link_libraries(STM32RTC INTERFACE STM32RTC_usage)
+
+
+
+add_library(STM32RTC_bin OBJECT EXCLUDE_FROM_ALL
+  src/rtc.c
+  src/STM32RTC.cpp
+)
+target_link_libraries(STM32RTC_bin PUBLIC STM32RTC_usage)
+
+target_link_libraries(STM32RTC INTERFACE
+  STM32RTC_bin
+  $<TARGET_OBJECTS:STM32RTC_bin>
+)
+