zephyr: allow dynamic numeration of flash_areas

Zephyr flash_map reworks caused that areas id exact number are
assigned dynamically.

This patch i counterpart to
zephyrproject-rtos/zephyr#8837

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

Author: nvlsianpu

boot/zephyr/flash_map_extended.c

@@ -49,12 +49,20 @@ int flash_device_base(uint8_t fd_id, uintptr_t *ret)
 }
 
 /*
- * This depends on the mappings defined in sysflash.h, and assumes
- * that slot 0, slot 1, and the scratch areas are contiguous.
+ * This depends on the mappings defined in sysflash.h.
+ * MCUBoot uses continuous numbering for slot 0, slot 1, and the scratch
+ * while zephyr might number it differently.
  */
 int flash_area_id_from_image_slot(int slot)
 {
-    return slot + FLASH_AREA_IMAGE_0;
+    static const int area_id_tab[] = {FLASH_AREA_IMAGE_0, FLASH_AREA_IMAGE_1,
+                                      FLASH_AREA_IMAGE_SCRATCH};
+
+    if (slot >= 0 && slot < ARRAY_SIZE(area_id_tab)) {
+        return area_id_tab[slot];
+    }
+
+    return -EINVAL; /* flash_area_open will fail on that */
 }
 
 int flash_area_sector_from_off(off_t off, struct flash_sector *sector)

boot/zephyr/include/sysflash/sysflash.h

@@ -3,8 +3,10 @@
 #ifndef __SYSFLASH_H__
 #define __SYSFLASH_H__
 
-#define FLASH_AREA_IMAGE_0 1
-#define FLASH_AREA_IMAGE_1 2
-#define FLASH_AREA_IMAGE_SCRATCH 3
+#include <generated_dts_board.h>
+
+#define FLASH_AREA_IMAGE_0 DT_FLASH_AREA_IMAGE_0_ID
+#define FLASH_AREA_IMAGE_1 DT_FLASH_AREA_IMAGE_1_ID
+#define FLASH_AREA_IMAGE_SCRATCH DT_FLASH_AREA_IMAGE_SCRATCH_ID
 
 #endif /* __SYSFLASH_H__ */

sim/mcuboot-sys/csupport/generated_dts_board.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* This file mocks zephyr's autogenerated DT output header file */
+
+#ifndef __GENERATED_DTS_BOARD_H__
+#define __GENERATED_DTS_BOARD_H__
+
+#define DT_FLASH_AREA_IMAGE_0_ID 1
+#define DT_FLASH_AREA_IMAGE_1_ID 2
+#define DT_FLASH_AREA_IMAGE_SCRATCH_ID 3
+
+#endif /*__GENERATED_DTS_BOARD_H__*/