bl2: add bl2_plat_handle_pre_image_load()

There are cases where we need to manipulate image information before
the load.  For example, for decompressing data, we cannot load the
compressed images to their final destination.  Instead, we need to
load them to the temporary buffer for the decompressor.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

bl2/bl2_image_load_v2.c

 /*
- * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -54,6 +54,12 @@ entry_point_info_t *bl2_load_images(void)
 			}
 		}
 
+		err = bl2_plat_handle_pre_image_load(bl2_node_info->image_id);
+		if (err) {
+			ERROR("BL2: Failure in pre image load handling (%i)\n", err);
+			plat_error_handler(err);
+		}
+
 		if (!(bl2_node_info->image_info->h.attr & IMAGE_ATTRIB_SKIP_LOADING)) {
 			INFO("BL2: Loading image id %d\n", bl2_node_info->image_id);
 			err = load_auth_image(bl2_node_info->image_id,

docs/porting-guide.rst

@@ -1424,10 +1424,22 @@ The purpose of this function is to return a pointer to a ``meminfo`` structure
 populated with the extents of secure RAM available for BL2 to use. See
 ``bl2_early_platform_setup()`` above.
 
-Following function is required only when LOAD\_IMAGE\_V2 is enabled.
+Following functions are optionally used only when LOAD\_IMAGE\_V2 is enabled.
 
-Function : bl2\_plat\_handle\_post\_image\_load() [mandatory]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Function : bl2\_plat\_handle\_pre\_image\_load() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : unsigned int
+    Return   : int
+
+This function can be used by the platforms to update/use image information
+for given ``image_id``. This function is currently invoked in BL2 before
+loading each image, when LOAD\_IMAGE\_V2 is enabled.
+
+Function : bl2\_plat\_handle\_post\_image\_load() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 ::
 
@@ -1435,9 +1447,8 @@ Function : bl2\_plat\_handle\_post\_image\_load() [mandatory]
     Return   : int
 
 This function can be used by the platforms to update/use image information
-for given ``image_id``. This function is currently invoked in BL2 to handle
-BL image specific information based on the ``image_id`` passed, when
-LOAD\_IMAGE\_V2 is enabled.
+for given ``image_id``. This function is currently invoked in BL2 after
+loading each image, when LOAD\_IMAGE\_V2 is enabled.
 
 Following functions are required only when LOAD\_IMAGE\_V2 is disabled.
 

include/plat/common/platform.h

 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -169,6 +169,7 @@ struct meminfo *bl2_plat_sec_mem_layout(void);
  * This function can be used by the platforms to update/use image
  * information for given `image_id`.
  */
+int bl2_plat_handle_pre_image_load(unsigned int image_id);
 int bl2_plat_handle_post_image_load(unsigned int image_id);
 
 #else /* LOAD_IMAGE_V2 */

plat/common/platform_helpers_default.c

@@ -13,6 +13,8 @@
 
 #pragma weak plat_error_handler
 #pragma weak bl2_plat_preload_setup
+#pragma weak bl2_plat_handle_pre_image_load
+#pragma weak bl2_plat_handle_post_image_load
 #pragma weak plat_try_next_boot_source
 
 void __dead2 plat_error_handler(int err)
@@ -25,6 +27,16 @@ void bl2_plat_preload_setup(void)
 {
 }
 
+int bl2_plat_handle_pre_image_load(unsigned int image_id)
+{
+	return 0;
+}
+
+int bl2_plat_handle_post_image_load(unsigned int image_id)
+{
+	return 0;
+}
+
 int plat_try_next_boot_source(void)
 {
 	return 0;