soc: stm32: symbol for application XiP from xspi external memory

Add a STM32_APP_IN_EXT_FLASH to determine that an application
is eXecuting in Place on an external xspi flash.
That will control the clock init of this external xspi controller.

Signed-off-by: Francois Ramu <[email protected]>

Author: FRASTM

soc/st/stm32/Kconfig

@@ -104,4 +104,12 @@ config STM32_BACKUP_PROTECTION
 	  Enabled for SoCs for which access protection to backup domain
 	  resources needs to be explicitly handled.
 
+config STM32_APP_IN_EXT_FLASH
+	bool
+	help
+	  Allows the SoC clock driver to correctly initialize the
+	  Q/O/XSPI controller clocks when the application is residing
+	  in external Flash and is chainloaded with MCUboot.
+	  Whether the app is eXecuted in Place (XiP) depends on the MCUboot mode used.
+
 endif # SOC_FAMILY_STM32

soc/st/stm32/Kconfig.defconfig

@@ -85,6 +85,9 @@ config FLASH_BASE_ADDRESS
 		if $(DT_FLASH_PARENT_IS_XSPI)
 	default $(dt_chosen_reg_addr_hex,$(DT_CHOSEN_Z_FLASH))
 
+config STM32_APP_IN_EXT_FLASH
+	default $(DT_FLASH_PARENT_IS_XSPI)
+
 # The XSPI PSRAM driver creates a SMH region with attribute SMH_REG_ATTR_EXTERNAL (2)
 # If applicable set the LTDC / VIDEO_BUFFER SMH attribute to SMH_REG_ATTR_EXTERNAL (2)
 # in order to be able to allocate from the XSPI PSRAM