zephyr/Kconfig: added option for enabling WDT feed

Added option for enabling feeding the watchdog while
doing the swap operation.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>

boot/zephyr/Kconfig

@@ -495,6 +495,16 @@ config MCUBOOT_HW_DOWNGRADE_PREVENTION
 
 endchoice
 
+config BOOT_WATCHDOG_FEED
+	bool "Feed the watchdog while doing swap"
+	default y if SOC_FAMILY_NRF
+	imply NRFX_WDT
+	imply NRFX_WDT0
+	imply NRFX_WDT1
+	help
+	  Enables implementation of MCUBOOT_WATCHDOG_FEED() macro which is
+	  used to feed watchdog while doing time consuming operations.
+
 endmenu
 
 config MCUBOOT_DEVICE_SETTINGS

boot/zephyr/include/mcuboot_config/mcuboot_config.h

@@ -154,6 +154,7 @@
 
 #endif /* !__BOOTSIM__ */
 
+#if CONFIG_BOOT_WATCHDOG_FEED
 #if CONFIG_NRFX_WDT
 #include <nrfx_wdt.h>
 
@@ -180,12 +181,18 @@
 #endif /* defined(CONFIG_NRFX_WDT0) && defined(CONFIG_NRFX_WDT1) */
 
 #else /* CONFIG_NRFX_WDT */
-
+#warning "MCUBOOT_WATCHDOG_FEED() is no-op"
+/* No vendor implementation, no-op for historical reasons */
+#define MCUBOOT_WATCHDOG_FEED()         \
+    do {                                \
+    } while (0)
+#endif /* CONFIG_NRFX_WDT */
+#else  /* CONFIG_BOOT_WATCHDOG_FEED */
+/* Not enabled, no feed activity */
 #define MCUBOOT_WATCHDOG_FEED()         \
     do {                                \
-        /* TODO: to be implemented */   \
     } while (0)
 
-#endif /* CONFIG_NRFX_WDT */
+#endif /* CONFIG_BOOT_WATCHDOG_FEED */
 
 #endif /* __MCUBOOT_CONFIG_H__ */