dfu: Add support for new MCUboot swap using offset mode

Allows using this newly introduced MCUboot algorithm

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

include/zephyr/dfu/mcuboot.h

@@ -81,6 +81,8 @@ extern "C" {
 
 #define BOOT_IMG_VER_STRLEN_MAX 25  /* 255.255.65535.4294967295\0 */
 
+/** Sector at which firmware update should be placed by application in swap using offset mode */
+#define SWAP_USING_OFFSET_SECTOR_UPDATE_BEGIN 1
 
 /**
  * @brief MCUboot image header representation for image version
@@ -287,6 +289,20 @@ ssize_t boot_get_area_trailer_status_offset(uint8_t area_id);
  */
 ssize_t boot_get_trailer_status_offset(size_t area_size);
 
+#if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET) || defined(__DOXYGEN__)
+/**
+ * @brief Get the offset of the image header, this should be used in swap using offset mode to
+ *	  account for the secondary slot data starting in the first or second sector, depending
+ *	  upon the current state
+ *
+ * @param area_id flash_area ID of image bank to get the status offset
+ * @return offset of the image header
+ */
+size_t boot_get_image_start_offset(uint8_t area_id);
+#else
+#define boot_get_image_start_offset(...) 0
+#endif
+
 #ifdef __cplusplus
 }
 #endif

modules/Kconfig.mcuboot

@@ -149,6 +149,15 @@ config MCUBOOT_BOOTLOADER_MODE_SINGLE_APP
 	  to DFU its own update to secondary slot and all updates need to
 	  be performed using MCUboot serial recovery.
 
+config MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET
+	bool "MCUboot has been configured for swap using offset operation"
+	select MCUBOOT_BOOTLOADER_MODE_HAS_NO_DOWNGRADE
+	help
+	  MCUboot expects slot0_partition and slot1_partition to be present
+	  in DT and application will boot from slot0_partition.
+	  MCUBOOT_BOOTLOADER_NO_DOWNGRADE should also be selected
+	  if MCUboot has been built with MCUBOOT_DOWNGRADE_PREVENTION.
+
 config MCUBOOT_BOOTLOADER_MODE_SWAP_USING_MOVE
 	bool "MCUboot has been configured for swap using move operation"
 	select MCUBOOT_BOOTLOADER_MODE_HAS_NO_DOWNGRADE

subsys/dfu/boot/mcuboot.c

@@ -42,6 +42,13 @@ LOG_MODULE_REGISTER(mcuboot_dfu, LOG_LEVEL_DBG);
 #define BOOT_HEADER_MAGIC_V1 0x96f3b83d
 #define BOOT_HEADER_SIZE_V1 32
 
+enum IMAGE_INDEXES {
+	IMAGE_INDEX_INVALID = -1,
+	IMAGE_INDEX_0,
+	IMAGE_INDEX_1,
+	IMAGE_INDEX_2
+};
+
 #if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_RAM_LOAD)
 /* For RAM LOAD mode, the active image must be fetched from the bootloader */
 #define ACTIVE_SLOT_FLASH_AREA_ID boot_fetch_active_slot()
@@ -99,11 +106,69 @@ uint8_t boot_fetch_active_slot(void)
 }
 #endif /* CONFIG_MCUBOOT_BOOTLOADER_MODE_RAM_LOAD */
 
+#if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET)
+size_t boot_get_image_start_offset(uint8_t area_id)
+{
+	size_t off = 0;
+	int image = IMAGE_INDEX_INVALID;
+
+	if (area_id == FIXED_PARTITION_ID(slot1_partition)) {
+		image = IMAGE_INDEX_0;
+#if FIXED_PARTITION_EXISTS(slot3_partition)
+	} else if (area_id == FIXED_PARTITION_ID(slot3_partition)) {
+		image = IMAGE_INDEX_1;
+#endif
+#if FIXED_PARTITION_EXISTS(slot5_partition)
+	} else if (area_id == FIXED_PARTITION_ID(slot5_partition)) {
+		image = IMAGE_INDEX_2;
+#endif
+	}
+
+	if (image != IMAGE_INDEX_INVALID) {
+		/* Need to check status from primary slot to get correct offset for secondary
+		 * slot image header
+		 */
+		const struct flash_area *fa;
+		uint32_t num_sectors = SWAP_USING_OFFSET_SECTOR_UPDATE_BEGIN;
+		struct flash_sector sector_data;
+		int rc;
+
+		rc = flash_area_open(area_id, &fa);
+		if (rc) {
+			LOG_ERR("Flash open area %u failed: %d", area_id, rc);
+			goto done;
+		}
+
+		if (mcuboot_swap_type_multi(image) != BOOT_SWAP_TYPE_REVERT) {
+			/* For swap using offset mode, the image starts in the second sector of
+			 * the upgrade slot, so apply the offset when this is needed, do this by
+			 * getting information on first sector only, this is expected to return an
+			 * error as there are more slots, so allow the not enough memory error
+			 */
+			rc = flash_area_get_sectors(area_id, &num_sectors, &sector_data);
+			if ((rc != 0 && rc != -ENOMEM) ||
+			    num_sectors != SWAP_USING_OFFSET_SECTOR_UPDATE_BEGIN) {
+				LOG_ERR("Failed to get sector details: %d", rc);
+			} else {
+				off = sector_data.fs_size;
+			}
+		}
+
+		flash_area_close(fa);
+	}
+
+done:
+	LOG_DBG("Start offset for area %u: 0x%x", area_id, off);
+	return off;
+}
+#endif /* CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET */
+
 static int boot_read_v1_header(uint8_t area_id,
 			       struct mcuboot_v1_raw_header *v1_raw)
 {
 	const struct flash_area *fa;
 	int rc;
+	size_t off = boot_get_image_start_offset(area_id);
 
 	rc = flash_area_open(area_id, &fa);
 	if (rc) {
@@ -111,27 +176,19 @@ static int boot_read_v1_header(uint8_t area_id,
 	}
 
 	/*
-	 * Read and sanity-check the raw header.
+	 * Read and validty-check the raw header.
 	 */
-	rc = flash_area_read(fa, 0, v1_raw, sizeof(*v1_raw));
+	rc = flash_area_read(fa, off, v1_raw, sizeof(*v1_raw));
 	flash_area_close(fa);
 	if (rc) {
 		return rc;
 	}
 
 	v1_raw->header_magic = sys_le32_to_cpu(v1_raw->header_magic);
-	v1_raw->image_load_address =
-		sys_le32_to_cpu(v1_raw->image_load_address);
 	v1_raw->header_size = sys_le16_to_cpu(v1_raw->header_size);
-	v1_raw->image_size = sys_le32_to_cpu(v1_raw->image_size);
-	v1_raw->image_flags = sys_le32_to_cpu(v1_raw->image_flags);
-	v1_raw->version.revision =
-		sys_le16_to_cpu(v1_raw->version.revision);
-	v1_raw->version.build_num =
-		sys_le32_to_cpu(v1_raw->version.build_num);
 
 	/*
-	 * Sanity checks.
+	 * Validity checks.
 	 *
 	 * Larger values in header_size than BOOT_HEADER_SIZE_V1 are
 	 * possible, e.g. if Zephyr was linked with
@@ -142,6 +199,16 @@ static int boot_read_v1_header(uint8_t area_id,
 		return -EIO;
 	}
 
+	v1_raw->image_load_address =
+		sys_le32_to_cpu(v1_raw->image_load_address);
+	v1_raw->header_size = sys_le16_to_cpu(v1_raw->header_size);
+	v1_raw->image_size = sys_le32_to_cpu(v1_raw->image_size);
+	v1_raw->image_flags = sys_le32_to_cpu(v1_raw->image_flags);
+	v1_raw->version.revision =
+		sys_le16_to_cpu(v1_raw->version.revision);
+	v1_raw->version.build_num =
+		sys_le32_to_cpu(v1_raw->version.build_num);
+
 	return 0;
 }
 

subsys/dfu/img_util/flash_img.c

@@ -1,19 +1,24 @@
 /*
- * Copyright (c) 2017, 2020 Nordic Semiconductor ASA
+ * Copyright (c) 2017-2025 Nordic Semiconductor ASA
  * Copyright (c) 2017 Linaro Limited
  * Copyright (c) 2020 Gerson Fernando Budke <nandojve@gmail.com>
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 #include <zephyr/types.h>
+#include <assert.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <string.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/dfu/mcuboot.h>
 #include <zephyr/dfu/flash_img.h>
 #include <zephyr/dfu/mcuboot.h>
 #include <zephyr/storage/flash_map.h>
 #include <zephyr/storage/stream_flash.h>
 
+LOG_MODULE_REGISTER(flash_img, CONFIG_IMG_MANAGER_LOG_LEVEL);
+
 #ifdef CONFIG_IMG_ERASE_PROGRESSIVELY
 #include <bootutil/bootutil_public.h>
 #endif
@@ -48,6 +53,9 @@ BUILD_ASSERT((CONFIG_IMG_BLOCK_BUF_SIZE % FLASH_WRITE_BLOCK_SIZE == 0),
 	     "FLASH_WRITE_BLOCK_SIZE");
 #endif
 
+#define FLASH_CHECK_ERASED_BUFFER_SIZE 16
+#define ERASED_VAL_32(x) (((x) << 24) | ((x) << 16) | ((x) << 8) | (x))
+
 static int scramble_mcuboot_trailer(struct flash_img_context *ctx)
 {
 	int rc = 0;
@@ -132,10 +140,64 @@ size_t flash_img_bytes_written(struct flash_img_context *ctx)
 	return stream_flash_bytes_written(&ctx->stream);
 }
 
+#if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET)
+/**
+ * Determines if the specified area of flash is completely unwritten.
+ *
+ * @param	fa	pointer to flash area to scan
+ *
+ * @return	0	when not empty, 1 when empty, negative errno code on error.
+ */
+static int flash_check_erased(const struct flash_area *fa)
+{
+	uint32_t data[FLASH_CHECK_ERASED_BUFFER_SIZE];
+	off_t addr;
+	off_t end;
+	int bytes_to_read;
+	int rc;
+	int i;
+	uint8_t erased_val;
+	uint32_t erased_val_32;
+
+	assert(fa->fa_size % sizeof(erased_val_32) == 0);
+
+	erased_val = flash_area_erased_val(fa);
+	erased_val_32 = ERASED_VAL_32(erased_val);
+
+	end = fa->fa_size;
+	for (addr = 0; addr < end; addr += sizeof(data)) {
+		if (end - addr < sizeof(data)) {
+			bytes_to_read = end - addr;
+		} else {
+			bytes_to_read = sizeof(data);
+		}
+
+		rc = flash_area_read(fa, addr, data, bytes_to_read);
+
+		if (rc < 0) {
+			LOG_ERR("Failed to read data from flash area: %d", rc);
+			return rc;
+		}
+
+		for (i = 0; i < bytes_to_read / sizeof(erased_val_32); i++) {
+			if (data[i] != erased_val_32) {
+				return 0;
+			}
+		}
+	}
+
+	return 1;
+}
+#endif
+
 int flash_img_init_id(struct flash_img_context *ctx, uint8_t area_id)
 {
 	int rc;
 	const struct device *flash_dev;
+#if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET)
+	uint32_t sector_count = SWAP_USING_OFFSET_SECTOR_UPDATE_BEGIN;
+	struct flash_sector sector_data;
+#endif
 
 	rc = flash_area_open(area_id,
 			       (const struct flash_area **)&(ctx->flash_area));
@@ -145,9 +207,45 @@ int flash_img_init_id(struct flash_img_context *ctx, uint8_t area_id)
 
 	flash_dev = flash_area_get_device(ctx->flash_area);
 
+#if defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET)
+	/* Query size of first sector in flash for upgrade slot, so it can be erased, and begin
+	 * upload started at the second sector
+	 */
+	rc = flash_area_sectors((const struct flash_area *)ctx->flash_area, &sector_count,
+				&sector_data);
+
+	if (rc && rc != -ENOMEM) {
+		flash_area_close(ctx->flash_area);
+		ctx->flash_area = NULL;
+		return rc;
+	} else if (sector_count != SWAP_USING_OFFSET_SECTOR_UPDATE_BEGIN) {
+		flash_area_close(ctx->flash_area);
+		ctx->flash_area = NULL;
+		return -ENOENT;
+	}
+
+	if (!flash_check_erased((const struct flash_area *)ctx->flash_area)) {
+		/* Flash is not empty, therefore flatten/erase the area to prevent issues when
+		 * the firmware update process begins
+		 */
+		rc = flash_area_flatten((const struct flash_area *)ctx->flash_area, 0,
+					sector_data.fs_size);
+
+		if (rc) {
+			flash_area_close(ctx->flash_area);
+			ctx->flash_area = NULL;
+			return rc;
+		}
+	}
+
+	return stream_flash_init(&ctx->stream, flash_dev, ctx->buf, CONFIG_IMG_BLOCK_BUF_SIZE,
+				 (ctx->flash_area->fa_off + sector_data.fs_size),
+				 (ctx->flash_area->fa_size - sector_data.fs_size), NULL);
+#else
 	return stream_flash_init(&ctx->stream, flash_dev, ctx->buf,
 			CONFIG_IMG_BLOCK_BUF_SIZE, ctx->flash_area->fa_off,
 			ctx->flash_area->fa_size, NULL);
+#endif
 }
 
 #ifdef CONFIG_MCUBOOT_BOOTLOADER_MODE_RAM_LOAD
@@ -194,7 +292,7 @@ int flash_img_check(struct flash_img_context *ctx,
 
 	fac.match = fic->match;
 	fac.clen = fic->clen;
-	fac.off = 0;
+	fac.off = boot_get_image_start_offset(area_id);
 	fac.rbuf = ctx->buf;
 	fac.rblen = sizeof(ctx->buf);
 

subsys/mgmt/mcumgr/grp/img_mgmt/src/img_mgmt.c

@@ -13,6 +13,7 @@
 #include <zephyr/toolchain.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/storage/flash_map.h>
+#include <zephyr/dfu/mcuboot.h>
 
 #include <zcbor_common.h>
 #include <zcbor_decode.h>
@@ -262,7 +263,10 @@ int img_mgmt_read_info(int image_slot, struct image_version *ver, uint8_t *hash,
 		return IMG_MGMT_ERR_FLASH_CONFIG_QUERY_FAIL;
 	}
 
-	rc = img_mgmt_read(image_slot, 0, &hdr, sizeof(hdr));
+	rc = img_mgmt_read(image_slot,
+			   boot_get_image_start_offset(img_mgmt_flash_area_id(image_slot)),
+			   &hdr, sizeof(hdr));
+
 	if (rc != 0) {
 		return rc;
 	}
@@ -290,7 +294,8 @@ int img_mgmt_read_info(int image_slot, struct image_version *ver, uint8_t *hash,
 	 * TLV. All images are required to have a hash TLV.  If the hash is missing, the image
 	 * is considered invalid.
 	 */
-	data_off = hdr.ih_hdr_size + hdr.ih_img_size;
+	data_off = hdr.ih_hdr_size + hdr.ih_img_size +
+		   boot_get_image_start_offset(img_mgmt_flash_area_id(image_slot));
 
 	rc = img_mgmt_find_tlvs(image_slot, &data_off, &data_end, IMAGE_TLV_PROT_INFO_MAGIC);
 	if (!rc) {

subsys/mgmt/mcumgr/grp/img_mgmt/src/zephyr_img_mgmt.c

@@ -441,6 +441,10 @@ int img_mgmt_erase_image_data(unsigned int off, unsigned int num_bytes)
 {
 	const struct flash_area *fa;
 	int rc;
+	const struct device *dev;
+	struct flash_pages_info page;
+	off_t page_offset;
+	size_t erase_size;
 
 	if (off != 0) {
 		rc = IMG_MGMT_ERR_INVALID_OFFSET;
@@ -454,16 +458,15 @@ int img_mgmt_erase_image_data(unsigned int off, unsigned int num_bytes)
 		goto end;
 	}
 
-	/* align requested erase size to the erase-block-size */
+	/* Align requested erase size to the erase-block-size */
-	const struct device *dev = flash_area_get_device(fa);
+	dev = flash_area_get_device(fa);
 
 	if (dev == NULL) {
 		rc = IMG_MGMT_ERR_FLASH_AREA_DEVICE_NULL;
 		goto end_fa;
 	}
-	struct flash_pages_info page;
-	off_t page_offset = fa->fa_off + num_bytes - 1;
 
+	page_offset = fa->fa_off + num_bytes - 1;
 	rc = flash_get_page_info_by_offs(dev, page_offset, &page);
 	if (rc != 0) {
 		LOG_ERR("bad offset (0x%lx)", (long)page_offset);
@@ -471,9 +474,9 @@ int img_mgmt_erase_image_data(unsigned int off, unsigned int num_bytes)
 		goto end_fa;
 	}
 
-	size_t erase_size = page.start_offset + page.size - fa->fa_off;
+	erase_size = page.start_offset + page.size - fa->fa_off;
-
+	rc = flash_area_flatten(fa, boot_get_image_start_offset(g_img_mgmt_state.area_id),
-	rc = flash_area_flatten(fa, 0, erase_size);
+				erase_size);
 
 	if (rc != 0) {
 		LOG_ERR("image slot erase of 0x%zx bytes failed (err %d)", erase_size,
@@ -568,6 +571,7 @@ int img_mgmt_upload_inspect(const struct img_mgmt_upload_req *req,
 		const struct flash_area *fa;
 #if defined(CONFIG_MCUMGR_GRP_IMG_TOO_LARGE_SYSBUILD) &&			\
 	(defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_WITHOUT_SCRATCH) ||	\
+	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_MOVE) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_SCRATCH) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_OVERWRITE_ONLY) ||		\
@@ -645,6 +649,7 @@ int img_mgmt_upload_inspect(const struct img_mgmt_upload_req *req,
 
 #if defined(CONFIG_MCUMGR_GRP_IMG_TOO_LARGE_SYSBUILD) &&			\
 	(defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_WITHOUT_SCRATCH) ||	\
+	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_MOVE) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_SCRATCH) ||		\
 	 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_OVERWRITE_ONLY) ||		\

subsys/mgmt/mcumgr/grp/os_mgmt/src/os_mgmt.c

@@ -430,6 +430,8 @@ os_mgmt_mcumgr_params(struct smp_streamer *ctxt)
 #define BOOTLOADER_MODE MCUBOOT_MODE_SWAP_USING_SCRATCH
 #elif defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_OVERWRITE_ONLY)
 #define BOOTLOADER_MODE MCUBOOT_MODE_UPGRADE_ONLY
+#elif defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_OFFSET)
+#define BOOTLOADER_MODE MCUBOOT_MODE_SWAP_USING_OFFSET
 #elif defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_USING_MOVE) || \
 defined(CONFIG_MCUBOOT_BOOTLOADER_MODE_SWAP_WITHOUT_SCRATCH)
 #define BOOTLOADER_MODE MCUBOOT_MODE_SWAP_USING_MOVE