Allow BL3-2 platform definitions to be optional

The generic image loading and IO FIP code no longer forces the
platform to create BL3-2 (Secure-EL1 Payload) specific
definitions. The BL3-2 loading code in bl2/bl2main.c is wrapped
by a #ifdef BL32_BASE blocks, allowing the BL3-2 definitions to
be optional. Similarly for the name_uuid array defintion in
drivers/io/io_fip.c.

Also update the porting guide to reflect this change.

The BL3-2 platform definitions remain non-configurably present
in the FVP port.

Fixes ARM-software/tf-issues#68

Change-Id: Iea28b4e94d87a31f5522f271e290919a8a955460

3 files changed, 39 insertions, 33 deletions

diff --git a/bl2/bl2_main.c b/bl2/bl2_main.c
index 33c63eef..81fecd67 100644
--- a/bl2/bl2_main.c
+++ b/bl2/bl2_main.c
@@ -134,32 +134,34 @@ void bl2_main(void)
 	bl2_plat_set_bl33_ep_info(bl2_to_bl31_params->bl33_image_info,
 				bl2_to_bl31_params->bl33_ep_info);
 
+
+#ifdef BL32_BASE
 	/*
 	 * Load the BL32 image if there's one. It is upto to platform
 	 * to specify where BL32 should be loaded if it exists. It
 	 * could create space in the secure sram or point to a
-	 * completely different memory. A zero size indicates that the
-	 * platform does not want to load a BL32 image.
+	 * completely different memory.
+	 *
+	 * If a platform does not want to attempt to load BL3-2 image
+	 * it must leave BL32_BASE undefined
 	 */
 	bl2_plat_get_bl32_meminfo(&bl32_mem_info);
-	if (bl32_mem_info.total_size) {
-		e = load_image(&bl32_mem_info,
-			       BL32_IMAGE_NAME,
-			       bl32_mem_info.attr &
-			       LOAD_MASK,
-			       BL32_BASE,
-			       bl2_to_bl31_params->bl32_image_info,
-			       bl2_to_bl31_params->bl32_ep_info);
-
-		/* Halt if failed to load normal world firmware. */
-		if (e) {
-			WARN("Failed to load BL3-2.\n");
-		} else {
-			bl2_plat_set_bl32_ep_info(
-				bl2_to_bl31_params->bl32_image_info,
-				bl2_to_bl31_params->bl32_ep_info);
-		}
+	e = load_image(&bl32_mem_info,
+		       BL32_IMAGE_NAME,
+		       bl32_mem_info.attr & LOAD_MASK,
+		       BL32_BASE,
+		       bl2_to_bl31_params->bl32_image_info,
+		       bl2_to_bl31_params->bl32_ep_info);
+
+	/* Issue a diagnostic if no Secure Payload could be loaded */
+	if (e) {
+		WARN("Failed to load BL3-2.\n");
+	} else {
+		bl2_plat_set_bl32_ep_info(
+			bl2_to_bl31_params->bl32_image_info,
+			bl2_to_bl31_params->bl32_ep_info);
 	}
+#endif /* BL32_BASE */
 
 	/*
 	 * Run BL31 via an SMC to BL1. Information on how to pass control to
diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index 721ba1b6..df0176e3 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -555,23 +555,24 @@ using the `platform_is_primary_cpu()` function. BL1 passed control to BL2 at
     if the platform wants to restrict the amount of memory visible to BL3-1.
     Details of this function are given below.
 
-4.  Loading the BL3-2 binary image (if present) in platform provided memory
-    using semi-hosting. To load the BL3-2 image, BL2 makes use of the
-    `bl32_meminfo` field in the `bl31_args` structure to which a pointer is
+4.  (Optional) Loading the BL3-2 binary image (if present) from platform
+    provided non-volatile storage. To load the BL3-2 image, BL2 makes use of
+    the `bl32_meminfo` field in the `bl31_args` structure to which a pointer is
     returned by the `bl2_get_bl31_args_ptr()` function. The platform also
-    defines the address in memory where BL3-2 is loaded through the constant
-    `BL32_BASE`. BL2 uses this information to determine if there is enough
-    memory to load the BL3-2 image.
-
-5.  Arranging to pass control to the BL3-2 image (if present) that has been
-    pre-loaded at `BL32_BASE`. BL2 populates an `el_change_info` structure
-    in memory provided by the platform with information about how BL3-1 should
-    pass control to the BL3-2 image. This structure follows the
+    defines the address in memory where BL3-2 is loaded through the optional
+    constant `BL32_BASE`. BL2 uses this information to determine if there is
+    enough memory to load the BL3-2 image. If `BL32_BASE` is not defined then
+    this and the following two steps are not performed.
+
+5.  (Optional) Arranging to pass control to the BL3-2 image (if present) that
+    has been pre-loaded at `BL32_BASE`. BL2 populates an `el_change_info`
+    structure in memory provided by the platform with information about how
+    BL3-1 should pass control to the BL3-2 image. This structure follows the
     `el_change_info` structure populated for the normal world BL image in 2.
     above.
 
-6.  Populating a `meminfo` structure with the following information in
-    memory that is accessible by BL3-1 immediately upon entry.
+6.  (Optional) Populating a `meminfo` structure with the following information
+    in memory that is accessible by BL3-1 immediately upon entry.
 
         meminfo.total_base = Base address of memory visible to BL3-2
         meminfo.total_size = Size of memory visible to BL3-2
@@ -581,7 +582,7 @@ using the `platform_is_primary_cpu()` function. BL1 passed control to BL2 at
                              BL3-2
 
     BL2 populates this information in the `bl32_meminfo` field of the pointer
-    returned by the `bl2_get_bl31_args_ptr() function.
+    returned by the `bl2_get_bl31_args_ptr()` function.
 
 The following functions must be implemented by the platform port to enable BL2
 to perform the above tasks.
diff --git a/drivers/io/io_fip.c b/drivers/io/io_fip.c
index 4848a706..8ed7f473 100644
--- a/drivers/io/io_fip.c
+++ b/drivers/io/io_fip.c
@@ -65,7 +65,10 @@ typedef struct {
 static const plat_fip_name_uuid_t name_uuid[] = {
 	{BL2_IMAGE_NAME, UUID_TRUSTED_BOOT_FIRMWARE_BL2},
 	{BL31_IMAGE_NAME, UUID_EL3_RUNTIME_FIRMWARE_BL31},
+#ifdef BL32_IMAGE_NAME
+	/* BL3-2 is optional in the platform */
 	{BL32_IMAGE_NAME, UUID_SECURE_PAYLOAD_BL32},
+#endif /* BL32_IMAGE_NAME */
 	{BL33_IMAGE_NAME, UUID_NON_TRUSTED_FIRMWARE_BL33},
 };