zephyr: Add direct-xip mode to Zephyr configuration

Add direct-xip mode to Zephyr configuration and make
upgrade mode selection always explicit.

Change-Id: Ia8e788f0b7bc801b6d45fd86f56c17ca6839f9c9
Co-authored-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
Signed-off-by: David Vincze <david.vincze@linaro.org>

boot/zephyr/Kconfig

@@ -164,18 +164,26 @@ config BOOT_VALIDATE_SLOT0
 	  able to modify the flash image itself.
 
 if !SINGLE_IMAGE_DFU
+choice
+	prompt "Image upgrade modes"
+	default BOOT_SWAP_USING_MOVE if SOC_FAMILY_NRF
+	default BOOT_SWAP_USING_SCRATCH
+
+config BOOT_SWAP_USING_SCRATCH
+	bool "Swap mode that run with the scratch partition"
+	help
+	  This is the most conservative swap mode but it can work even on
+	  devices with heterogeneous flash page layout.
+
 config BOOT_UPGRADE_ONLY
 	bool "Overwrite image updates instead of swapping"
-	default n
 	help
 	  If y, overwrite the primary slot with the upgrade image instead
 	  of swapping them. This prevents the fallback recovery, but
 	  uses a much simpler code path.
 
 config BOOT_SWAP_USING_MOVE
 	bool "Swap mode that can run without a scratch partition"
-	default y if SOC_FAMILY_NRF
-	default n
 	help
 	  If y, the swap upgrade is done in two steps, where first every
 	  sector of the primary slot is moved up one sector, then for
@@ -185,6 +193,17 @@ config BOOT_SWAP_USING_MOVE
 	  This allows a swap upgrade without using a scratch partition,
 	  but is currently limited to all sectors in both slots being of
 	  the same size.
+
+config BOOT_DIRECT_XIP
+	bool "Run the latest image directly from its slot"
+	help
+	  If y, mcuboot selects the newest valid image based on the image version
+	  numbers, thereafter the selected image can run directly from its slot
+	  without having to move/copy it into the primary slot. For this reason the
+	  images must be linked to be executed from the given image slot. Using this
+	  mode results in a simpler code path and smaller code size.
+
+endchoice
 endif
 
 if !SINGLE_IMAGE_DFU

boot/zephyr/include/mcuboot_config/mcuboot_config.h

@@ -66,6 +66,10 @@
 #define MCUBOOT_SWAP_USING_MOVE 1
 #endif
 
+#ifdef CONFIG_BOOT_DIRECT_XIP
+#define MCUBOOT_DIRECT_XIP
+#endif
+
 #ifdef CONFIG_UPDATEABLE_IMAGE_NUMBER
 #define MCUBOOT_IMAGE_NUMBER    CONFIG_UPDATEABLE_IMAGE_NUMBER
 #else