Boot: Extend flash layout for multiple images

This patch introduces the BOOT_IMAGE_NUMBER macro and current_image
variable to support multiple updatable images and the associated
extended flash layout.

The FLASH_AREA_IMAGE_* object-like macros are replaced with
function-like ones and therefore some functions have been updated,
because the labels of a switch statement and the initialization
values of objects with static storage duration have to be constant
expressions.

Change-Id: Ib7b26ec3c94233e52db4f97825ddb6a3e55bb1d3
Signed-off-by: David Vincze <david.vincze@arm.com>
diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index 041f6a2..b2a07d0 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -172,13 +172,12 @@
 int
 boot_status_entries(const struct flash_area *fap)
 {
-    switch (fap->fa_id) {
-    case FLASH_AREA_IMAGE_PRIMARY:
-    case FLASH_AREA_IMAGE_SECONDARY:
-        return BOOT_STATUS_STATE_COUNT * BOOT_STATUS_MAX_ENTRIES;
-    case FLASH_AREA_IMAGE_SCRATCH:
+    if (fap->fa_id == FLASH_AREA_IMAGE_SCRATCH) {
         return BOOT_STATUS_STATE_COUNT;
-    default:
+    } else if ((fap->fa_id == FLASH_AREA_IMAGE_PRIMARY) ||
+               (fap->fa_id == FLASH_AREA_IMAGE_SECONDARY)) {
+        return BOOT_STATUS_STATE_COUNT * BOOT_STATUS_MAX_ENTRIES;
+    } else {
         return BOOT_EBADARGS;
     }
 }
@@ -301,16 +300,14 @@
     const struct flash_area *fap;
     int rc;
 
-    switch (flash_area_id) {
-    case FLASH_AREA_IMAGE_SCRATCH:
-    case FLASH_AREA_IMAGE_PRIMARY:
-    case FLASH_AREA_IMAGE_SECONDARY:
+    if (flash_area_id == FLASH_AREA_IMAGE_SCRATCH ||
+        flash_area_id == FLASH_AREA_IMAGE_PRIMARY ||
+        flash_area_id == FLASH_AREA_IMAGE_SECONDARY) {
         rc = flash_area_open(flash_area_id, &fap);
         if (rc != 0) {
             return BOOT_EFLASH;
         }
-        break;
-    default:
+    } else {
         return BOOT_EBADARGS;
     }
 
diff --git a/boot/bootutil/src/bootutil_priv.h b/boot/bootutil/src/bootutil_priv.h
index bc35a72..11d0a54 100644
--- a/boot/bootutil/src/bootutil_priv.h
+++ b/boot/bootutil/src/bootutil_priv.h
@@ -134,6 +134,12 @@
     uint8_t image_num;  /* Boot status belongs to this image */
 };
 
+#ifdef MCUBOOT_IMAGE_NUMBER
+#define BOOT_IMAGE_NUMBER          MCUBOOT_IMAGE_NUMBER
+#else
+#define BOOT_IMAGE_NUMBER          1
+#endif
+
 #define BOOT_MAX_IMG_SECTORS       MCUBOOT_MAX_IMG_SECTORS
 
 /*
@@ -302,23 +308,21 @@
     int num_sectors = BOOT_MAX_IMG_SECTORS;
     int rc;
 
-    switch (flash_area) {
-    case FLASH_AREA_IMAGE_PRIMARY:
+    if (flash_area == FLASH_AREA_IMAGE_PRIMARY) {
         rc = flash_area_to_sectors(flash_area, &num_sectors,
                                    state->imgs[BOOT_PRIMARY_SLOT].sectors);
         state->imgs[BOOT_PRIMARY_SLOT].num_sectors = (size_t)num_sectors;
-        break;
-    case FLASH_AREA_IMAGE_SECONDARY:
+
+    } else if (flash_area == FLASH_AREA_IMAGE_SECONDARY) {
         rc = flash_area_to_sectors(flash_area, &num_sectors,
                                    state->imgs[BOOT_SECONDARY_SLOT].sectors);
         state->imgs[BOOT_SECONDARY_SLOT].num_sectors = (size_t)num_sectors;
-        break;
-    case FLASH_AREA_IMAGE_SCRATCH:
+
+    } else if (flash_area == FLASH_AREA_IMAGE_SCRATCH) {
         rc = flash_area_to_sectors(flash_area, &num_sectors,
                                    state->scratch.sectors);
         state->scratch.num_sectors = (size_t)num_sectors;
-        break;
-    default:
+    } else {
         return BOOT_EFLASH;
     }
 
@@ -350,24 +354,19 @@
     size_t *out_num_sectors;
     int rc;
 
-    switch (flash_area) {
-    case FLASH_AREA_IMAGE_PRIMARY:
-        num_sectors = BOOT_MAX_IMG_SECTORS;
+    num_sectors = BOOT_MAX_IMG_SECTORS;
+
+    if (flash_area == FLASH_AREA_IMAGE_PRIMARY) {
         out_sectors = state->imgs[BOOT_PRIMARY_SLOT].sectors;
         out_num_sectors = &state->imgs[BOOT_PRIMARY_SLOT].num_sectors;
-        break;
-    case FLASH_AREA_IMAGE_SECONDARY:
-        num_sectors = BOOT_MAX_IMG_SECTORS;
+    } else if (flash_area == FLASH_AREA_IMAGE_SECONDARY) {
         out_sectors = state->imgs[BOOT_SECONDARY_SLOT].sectors;
         out_num_sectors = &state->imgs[BOOT_SECONDARY_SLOT].num_sectors;
-        break;
-    case FLASH_AREA_IMAGE_SCRATCH:
-        num_sectors = BOOT_MAX_IMG_SECTORS;
+    } else if (flash_area == FLASH_AREA_IMAGE_SCRATCH) {
         out_sectors = state->scratch.sectors;
         out_num_sectors = &state->scratch.num_sectors;
-        break;
-    default:
-        return -1;
+    } else {
+        return BOOT_EFLASH;
     }
 
     rc = flash_area_get_sectors(flash_area, &num_sectors, out_sectors);
diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index fcbf082..a843d73 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -47,6 +47,7 @@
 MCUBOOT_LOG_MODULE_DECLARE(mcuboot);
 
 static struct boot_loader_state boot_data;
+uint8_t current_image = 0;
 
 #if defined(MCUBOOT_VALIDATE_PRIMARY_SLOT) && !defined(MCUBOOT_OVERWRITE_ONLY)
 static int boot_status_fails = 0;
@@ -1021,18 +1022,20 @@
     uint32_t total_sz;
     uint32_t off;
     uint32_t sz;
+    int fa_id_primary;
+    int fa_id_secondary;
     int rc;
 
     BOOT_LOG_DBG("erasing trailer; fa_id=%d", fap->fa_id);
 
-    switch (fap->fa_id) {
-    case FLASH_AREA_IMAGE_PRIMARY:
+    fa_id_primary   = flash_area_id_from_image_slot(BOOT_PRIMARY_SLOT);
+    fa_id_secondary = flash_area_id_from_image_slot(BOOT_SECONDARY_SLOT);
+
+    if (fap->fa_id == fa_id_primary) {
         slot = BOOT_PRIMARY_SLOT;
-        break;
-    case FLASH_AREA_IMAGE_SECONDARY:
+    } else if (fap->fa_id == fa_id_secondary) {
         slot = BOOT_SECONDARY_SLOT;
-        break;
-    default:
+    } else {
         return BOOT_EFLASH;
     }
 
diff --git a/boot/zephyr/flash_map_extended.c b/boot/zephyr/flash_map_extended.c
index 543a467..535e69a 100644
--- a/boot/zephyr/flash_map_extended.c
+++ b/boot/zephyr/flash_map_extended.c
@@ -55,9 +55,12 @@
  */
 int flash_area_id_from_image_slot(int slot)
 {
-    static const int area_id_tab[] = {FLASH_AREA_IMAGE_PRIMARY,
-                                      FLASH_AREA_IMAGE_SECONDARY,
-                                      FLASH_AREA_IMAGE_SCRATCH};
+#if (MCUBOOT_IMAGE_NUMBER == 1)
+    static
+#endif
+    const int area_id_tab[] = {FLASH_AREA_IMAGE_PRIMARY,
+                               FLASH_AREA_IMAGE_SECONDARY,
+                               FLASH_AREA_IMAGE_SCRATCH};
 
     if (slot >= 0 && slot < ARRAY_SIZE(area_id_tab)) {
         return area_id_tab[slot];
@@ -68,15 +71,15 @@
 
 int flash_area_id_to_image_slot(int area_id)
 {
-    switch (area_id) {
-    case FLASH_AREA_IMAGE_PRIMARY:
+    if (area_id == FLASH_AREA_IMAGE_PRIMARY) {
         return 0;
-    case FLASH_AREA_IMAGE_SECONDARY:
-        return 1;
-    default:
-        BOOT_LOG_ERR("invalid flash area ID");
-        return -1;
     }
+    if (area_id == FLASH_AREA_IMAGE_SECONDARY) {
+        return 1;
+    }
+
+    BOOT_LOG_ERR("invalid flash area ID");
+    return -1;
 }
 
 int flash_area_sector_from_off(off_t off, struct flash_sector *sector)
diff --git a/boot/zephyr/include/mcuboot_config/mcuboot_config.h b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
index d79d556..925591c 100644
--- a/boot/zephyr/include/mcuboot_config/mcuboot_config.h
+++ b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018 Open Source Foundries Limited
+ * Copyright (c) 2019 Arm Limited
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -65,6 +66,12 @@
 #define MCUBOOT_BOOTSTRAP 1
 #endif
 
+#ifdef CONFIG_UPDATEABLE_IMAGE_NUMBER
+#define MCUBOOT_IMAGE_NUMBER    CONFIG_UPDATEABLE_IMAGE_NUMBER
+#else
+#define MCUBOOT_IMAGE_NUMBER    1
+#endif
+
 /*
  * Enabling this option uses newer flash map APIs. This saves RAM and
  * avoids deprecated API usage.
diff --git a/boot/zephyr/include/sysflash/sysflash.h b/boot/zephyr/include/sysflash/sysflash.h
index 2492244..d4617bb 100644
--- a/boot/zephyr/include/sysflash/sysflash.h
+++ b/boot/zephyr/include/sysflash/sysflash.h
@@ -4,9 +4,32 @@
 #define __SYSFLASH_H__
 
 #include <generated_dts_board.h>
+#include <mcuboot_config/mcuboot_config.h>
 
+extern uint8_t current_image;
+
+#if (MCUBOOT_IMAGE_NUMBER == 1)
 #define FLASH_AREA_IMAGE_PRIMARY    DT_FLASH_AREA_IMAGE_0_ID
 #define FLASH_AREA_IMAGE_SECONDARY  DT_FLASH_AREA_IMAGE_1_ID
+#elif (MCUBOOT_IMAGE_NUMBER == 2)
+/* MCUBoot currently supports only up to 2 updateable firmware images.
+ * If the number of the current image is greater than MCUBOOT_IMAGE_NUMBER - 1
+ * then a dummy value will be assigned to the flash area macros.
+ */
+#define FLASH_AREA_IMAGE_PRIMARY    ((current_image == 0) ?         \
+                                         DT_FLASH_AREA_IMAGE_0_ID : \
+                                     (current_image == 1) ?         \
+                                         DT_FLASH_AREA_IMAGE_2_ID : \
+                                         255 )
+#define FLASH_AREA_IMAGE_SECONDARY  ((current_image == 0) ?         \
+                                         DT_FLASH_AREA_IMAGE_1_ID : \
+                                     (current_image == 1) ?         \
+                                         DT_FLASH_AREA_IMAGE_3_ID : \
+                                         255 )
+#else
+#error "Image slot and flash area mapping is not defined"
+#endif
+
 #define FLASH_AREA_IMAGE_SCRATCH    DT_FLASH_AREA_IMAGE_SCRATCH_ID
 
 #endif /* __SYSFLASH_H__ */
diff --git a/boot/zephyr/include/target.h b/boot/zephyr/include/target.h
index 6e777fb..a11616f 100644
--- a/boot/zephyr/include/target.h
+++ b/boot/zephyr/include/target.h
@@ -1,5 +1,7 @@
 /*
  *  Copyright (C) 2017, Linaro Ltd
+ *  Copyright (c) 2019, Arm Limited
+ *
  *  SPDX-License-Identifier: Apache-2.0
  */
 
@@ -45,4 +47,11 @@
 #error "Target support is incomplete; cannot build mcuboot."
 #endif
 
+#if ((MCUBOOT_IMAGE_NUMBER == 2) && (!defined(FLASH_AREA_IMAGE_2_OFFSET) || \
+                                     !defined(FLASH_AREA_IMAGE_2_SIZE)   || \
+                                     !defined(FLASH_AREA_IMAGE_3_OFFSET) || \
+                                     !defined(FLASH_AREA_IMAGE_3_SIZE)))
+#error "Target support is incomplete; cannot build mcuboot."
 #endif
+
+#endif /* H_TARGETS_TARGET_ */