Implement late binding for runtime hooks

At present SPD power management hooks and BL3-2 entry are implemented
using weak references. This would have the handlers bound and registered
with the core framework at build time, but leaves them dangling if a
service fails to initialize at runtime.

This patch replaces implementation by requiring runtime handlers to
register power management and deferred initialization hooks with the
core framework at runtime. The runtime services are to register the
hooks only as the last step, after having all states successfully
initialized.

Change-Id: Ibe788a2a381ef39aec1d4af5ba02376e67269782

1 files changed, 30 insertions, 10 deletions

diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index ea44871c..82449f5e 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -40,6 +40,15 @@
 #include <runtime_svc.h>
 #include <context_mgmt.h>
 
+
+/*******************************************************************************
+ * This function pointer is used to initialise the BL32 image. It's initialized
+ * by SPD calling bl31_register_bl32_init after setting up all things necessary
+ * for SP execution. In cases where both SPD and SP are absent, or when SPD
+ * finds it impossible to execute SP, this pointer is left as NULL
+ ******************************************************************************/
+static int32_t (*bl32_init)(meminfo *);
+
 /*******************************************************************************
  * Variable to indicate whether next image to execute after BL31 is BL33
  * (non-secure & default) or BL32 (secure).
@@ -97,19 +106,21 @@ void bl31_main(void)
 	write_vbar_el3((uint64_t) runtime_exceptions);
 
 	/*
-	 * All the cold boot actions on the primary cpu are done. We
-	 * now need to decide which is the next image (BL32 or BL33)
-	 * and how to execute it. If the SPD runtime service is
-	 * present, it would want to pass control to BL32 first in
-	 * S-EL1. It will export the bl32_init() routine where it takes
-	 * responsibility of entering S-EL1 and returning control back
-	 * to bl31_main. Once this is done we can prepare entry into
-	 * BL33 as normal.
+	 * All the cold boot actions on the primary cpu are done. We now need to
+	 * decide which is the next image (BL32 or BL33) and how to execute it.
+	 * If the SPD runtime service is present, it would want to pass control
+	 * to BL32 first in S-EL1. In that case, SPD would have registered a
+	 * function to intialize bl32 where it takes responsibility of entering
+	 * S-EL1 and returning control back to bl31_main. Once this is done we
+	 * can prepare entry into BL33 as normal.
 	 */
 
-	/* Tell BL32 about it memory extents as well */
+	/*
+	 * If SPD had registerd an init hook, invoke it. Pass it the information
+	 * about memory extents
+	 */
 	if (bl32_init)
-		bl32_init(bl31_plat_get_bl32_mem_layout());
+		(*bl32_init)(bl31_plat_get_bl32_mem_layout());
 
 	/*
 	 * We are ready to enter the next EL. Prepare entry into the image
@@ -175,3 +186,12 @@ void bl31_prepare_next_image_entry()
 	/* Finally set the next context */
 	cm_set_next_eret_context(next_image_info->security_state);
 }
+
+/*******************************************************************************
+ * This function initializes the pointer to BL32 init function. This is expected
+ * to be called by the SPD after it finishes all its initialization
+ ******************************************************************************/
+void bl31_register_bl32_init(int32_t (*func)(meminfo *))
+{
+	bl32_init = func;
+}