[nrf fromlist] susbys/dfu/img_util: refined ERASE PROGRESSIVELY implementation

Moved MCUboot trailer's status erase ahead any write operation,
which is step which helps with addition of support for devices
don't require explicit pager erase.
For these kind of devices flattening of mcuboot image status in
the trailer was introduced.

Upstream PR: zephyrproject-rtos/zephyr#79152

Signed-off-by: Andrzej Puzdrowski <[email protected]>

Author: nvlsianpu

subsys/dfu/Kconfig

@@ -68,8 +68,7 @@ config IMG_BLOCK_BUF_SIZE
 
 config IMG_ERASE_PROGRESSIVELY
 	bool "Erase flash progressively when receiving new firmware"
-	select STREAM_FLASH_ERASE
-	depends on FLASH_HAS_EXPLICIT_ERASE
+	select STREAM_FLASH_ERASE if FLASH_HAS_EXPLICIT_ERASE
 	help
 	  If enabled, flash is erased as necessary when receiving new firmware,
 	  instead of erasing the whole image slot at once. This is necessary

subsys/dfu/img_util/flash_img.c

@@ -43,26 +43,78 @@ BUILD_ASSERT((CONFIG_IMG_BLOCK_BUF_SIZE % FLASH_WRITE_BLOCK_SIZE == 0),
 	     "FLASH_WRITE_BLOCK_SIZE");
 #endif
 
+static int scramble_mcuboot_trailer(struct flash_img_context *ctx)
+{
+	int rc = 0;
+
+#ifdef CONFIG_IMG_ERASE_PROGRESSIVELY
+	if (stream_flash_bytes_written(&ctx->stream) == 0) {
+		off_t toff = boot_get_trailer_status_offset(ctx->flash_area->fa_size);
+		off_t offset;
+		size_t size;
+		const struct flash_parameters *fparams =
+			flash_get_parameters(flash_area_get_device(ctx->flash_area));
+#ifdef CONFIG_STREAM_FLASH_ERASE
+		/* for erasable devices prgressive-erase works only along with
+		 * CONFIG_STREAM_FLASH_ERASE option.
+		 */
+		if (flash_params_get_erase_cap(fparams) & FLASH_ERASE_C_EXPLICIT) {
+			/* On devices with explicit erase we are aligning to page
+			 * layout.
+			 */
+			struct flash_pages_info info;
+
+			rc = flash_get_page_info_by_offs(flash_area_get_device(ctx->flash_area),
+							 toff, &info);
+			if (rc != 0) {
+				return rc;
+			}
+			offset = info.start_offset;
+			size = info.size;
+
+		} else
+#endif
+		{
+			/* On devices with no erase, we are aligning to write block
+			 * size.
+			 */
+			offset = (toff + fparams->write_block_size - 1) &
+				 ~(fparams->write_block_size - 1);
+			/* No alignment correction needed here, offset is corrected already
+			 * and, size should be aligned.
+			 */
+			size = ctx->flash_area->fa_size - offset;
+		}
+
+		rc = flash_area_flatten(ctx->flash_area, offset, size);
+	}
+#endif
+
+	return rc;
+}
+
+
 int flash_img_buffered_write(struct flash_img_context *ctx, const uint8_t *data,
 			     size_t len, bool flush)
 {
 	int rc;
 
-	rc = stream_flash_buffered_write(&ctx->stream, data, len, flush);
-	if (!flush) {
+	/* If there is a need to erase the trailer, that should happen before any
+	 * write is done to partition.
+	 */
+	rc = scramble_mcuboot_trailer(ctx);
+	if (rc != 0) {
 		return rc;
 	}
 
-#ifdef CONFIG_IMG_ERASE_PROGRESSIVELY
-	ssize_t status_offset = boot_get_trailer_status_offset(
-		ctx->flash_area->fa_size);
-	rc = stream_flash_erase_page(&ctx->stream,
-				ctx->flash_area->fa_off +
-				status_offset);
-	if (rc) {
+
+	/* if CONFIG_IMG_ERASE_PROGRESSIVELY is enabled the enabled CONFIG_STREAM_FLASH_ERASE
+	 * ensures that stream_flash erases flash progresively.
+	 */
+	rc = stream_flash_buffered_write(&ctx->stream, data, len, flush);
+	if (!flush) {
 		return rc;
 	}
-#endif
 
 	flash_area_close(ctx->flash_area);
 	ctx->flash_area = NULL;