boot: zephyr: Add MCUboot status callback support

Adds an optional callback when the MCUboot status changes which can
allow components to react.

Signed-off-by: Jamie McCrae <jamie.mccrae@lairdconnect.com>

boot/bootutil/include/bootutil/mcuboot_status.h

@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2022, Laird Connectivity
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef H_MCUBOOT_STATUS_
+#define H_MCUBOOT_STATUS_
+
+/* Enumeration representing the states that MCUboot can be in */
+typedef enum
+{
+	MCUBOOT_STATUS_STARTUP = 0,
+	MCUBOOT_STATUS_UPGRADING,
+	MCUBOOT_STATUS_BOOTABLE_IMAGE_FOUND,
+	MCUBOOT_STATUS_NO_BOOTABLE_IMAGE_FOUND,
+	MCUBOOT_STATUS_BOOT_FAILED,
+	MCUBOOT_STATUS_USB_DFU_WAITING,
+	MCUBOOT_STATUS_USB_DFU_ENTERED,
+	MCUBOOT_STATUS_USB_DFU_TIMED_OUT,
+	MCUBOOT_STATUS_SERIAL_DFU_ENTERED,
+} mcuboot_status_type_t;
+
+#if defined(CONFIG_MCUBOOT_ACTION_HOOKS)
+extern void mcuboot_status_change(mcuboot_status_type_t status);
+#else
+#define mcuboot_status_change(_status) do {} while (0)
+#endif
+
+#endif /* H_MCUBOOT_STATUS_ */

boot/bootutil/src/loader.c

@@ -46,6 +46,7 @@
 #include "bootutil/fault_injection_hardening.h"
 #include "bootutil/ramload.h"
 #include "bootutil/boot_hooks.h"
+#include "bootutil/mcuboot_status.h"
 
 #ifdef MCUBOOT_ENC_IMAGES
 #include "bootutil/enc_key.h"
@@ -1998,6 +1999,9 @@ context_boot_go(struct boot_loader_state *state, struct boot_rsp *rsp)
     }
 #endif
 
+    /* Trigger status change callback with upgrading status */
+    mcuboot_status_change(MCUBOOT_STATUS_UPGRADING);
+
     /* Iterate over all the images. At this point there are no aborted swaps
      * and the swap types are determined for each image. By the end of the loop
      * all required update operations will have been finished.

boot/zephyr/Kconfig

@@ -582,6 +582,16 @@ config BOOT_IMAGE_ACCESS_HOOKS_FILE
 	  located. If the key file is not there, the build system uses relative
 	  path that starts from the zephyr port cmake directory (boot/zephyr/).
 
+config MCUBOOT_ACTION_HOOKS
+	bool "Enable hooks for responding to MCUboot status changes"
+	help
+	  This will call a handler when the MCUboot status changes which allows
+	  for some level of user feedback, for instance to change LED status to
+	  indicate a failure, using the callback:
+	  'void mcuboot_status_change(mcuboot_status_type_t status)' where
+	  'mcuboot_status_type_t' is listed in
+	  boot/bootutil/include/bootutil/mcuboot_status.h
+
 endmenu
 
 config MCUBOOT_DEVICE_SETTINGS

boot/zephyr/main.c

@@ -33,6 +33,7 @@
 #include "bootutil/image.h"
 #include "bootutil/bootutil.h"
 #include "bootutil/fault_injection_hardening.h"
+#include "bootutil/mcuboot_status.h"
 #include "flash_map_backend/flash_map_backend.h"
 
 #ifdef CONFIG_MCUBOOT_SERIAL
@@ -452,6 +453,8 @@ void main(void)
 
     (void)rc;
 
+    mcuboot_status_change(MCUBOOT_STATUS_STARTUP);
+
 #if (!defined(CONFIG_XTENSA) && DT_HAS_CHOSEN(zephyr_flash_controller))
     if (!flash_device_get_binding(DT_LABEL(DT_CHOSEN(zephyr_flash_controller)))) {
         BOOT_LOG_ERR("Flash device %s not found",
@@ -477,6 +480,8 @@ void main(void)
         gpio_pin_set_dt(&led0, 1);
 #endif
 
+        mcuboot_status_change(MCUBOOT_STATUS_SERIAL_DFU_ENTERED);
+
         BOOT_LOG_INF("Enter the serial recovery mode");
         rc = boot_console_init();
         __ASSERT(rc == 0, "Error initializing boot console.\n");
@@ -493,6 +498,9 @@ void main(void)
 #ifdef CONFIG_MCUBOOT_INDICATION_LED
         gpio_pin_set_dt(&led0, 1);
 #endif
+
+        mcuboot_status_change(MCUBOOT_STATUS_USB_DFU_ENTERED);
+
         rc = usb_enable(NULL);
         if (rc) {
             BOOT_LOG_ERR("Cannot enable USB");
@@ -508,8 +516,13 @@ void main(void)
         BOOT_LOG_ERR("Cannot enable USB");
     } else {
         BOOT_LOG_INF("Waiting for USB DFU");
+
+        mcuboot_status_change(MCUBOOT_STATUS_USB_DFU_WAITING);
+
         wait_for_usb_dfu(K_MSEC(CONFIG_BOOT_USB_DFU_WAIT_DELAY_MS));
         BOOT_LOG_INF("USB DFU wait time elapsed");
+
+        mcuboot_status_change(MCUBOOT_STATUS_USB_DFU_TIMED_OUT);
     }
 #endif
 
@@ -537,6 +550,9 @@ void main(void)
 
     if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
         BOOT_LOG_ERR("Unable to find bootable image");
+
+        mcuboot_status_change(MCUBOOT_STATUS_NO_BOOTABLE_IMAGE_FOUND);
+
         FIH_PANIC;
     }
 
@@ -548,9 +564,14 @@ void main(void)
 #else
     BOOT_LOG_INF("Jumping to the first image slot");
 #endif
+
+    mcuboot_status_change(MCUBOOT_STATUS_BOOTABLE_IMAGE_FOUND);
+
     ZEPHYR_BOOT_LOG_STOP();
     do_boot(&rsp);
 
+    mcuboot_status_change(MCUBOOT_STATUS_BOOT_FAILED);
+
     BOOT_LOG_ERR("Never should get here");
     while (1)
         ;