boot: Multi-image boot for direct-xip and ram-load

Multiple image boot support is implemented for direct-xip and ram-load
strategies. Dependency checking is also added, and for ram-load more
executable ram regions can be set.
Wrapper functions are intoduced to all boot strategies.

Change-Id: I59b346277dcb2c17cef4800f1e556b4ea9144845
Signed-off-by: Mark Horvath <mark.horvath@arm.com>

Author: mark-horvath-arm

boot/bootutil/include/bootutil/ramload.h

@@ -0,0 +1,35 @@
+/*
+ *  Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef __RAMLOAD_H__
+#define __RAMLOAD_H__
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef MULTIPLE_EXECUTABLE_RAM_REGIONS
+/**
+ * Provides information about the Executable RAM for a given image ID.
+ *
+ * @param image_id        Index of the image (from 0).
+ * @param exec_ram_start  Pointer to store the start address of the exec RAM
+ * @param exec_ram_size   Pointer to store the size of the exec RAM
+ *
+ * @return                0 on success; nonzero on failure.
+ */
+int boot_get_image_exec_ram_info(uint32_t image_id,
+                                 uint32_t *exec_ram_start,
+                                 uint32_t *exec_ram_size);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __RAMLOAD_H__ */

boot/bootutil/src/bootutil_priv.h

@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2017-2020 Linaro LTD
  * Copyright (c) 2017-2019 JUUL Labs
- * Copyright (c) 2019-2020 Arm Limited
+ * Copyright (c) 2019-2021 Arm Limited
  *
  * Original license:
  *
@@ -143,9 +143,6 @@ _Static_assert(BOOT_IMAGE_NUMBER > 0, "Invalid value for BOOT_IMAGE_NUMBER");
 #else
 #define ARE_SLOTS_EQUIVALENT()    1
 
-#if (BOOT_IMAGE_NUMBER != 1)
-#error "The MCUBOOT_DIRECT_XIP and MCUBOOT_RAM_LOAD mode only supports single-image boot (MCUBOOT_IMAGE_NUMBER=1)."
-#endif
 #ifdef MCUBOOT_ENC_IMAGES
 #error "Image encryption (MCUBOOT_ENC_IMAGES) is not supported when MCUBOOT_DIRECT_XIP or MCUBOOT_RAM_LOAD mode is selected."
 #endif