Pass the entry point info to bl1_plat_prepare_exit()

This patch modifies the prototype of the bl1_plat_prepare_exit()
platform API to pass the address of the entry point info structure
received from BL2. The structure contains information that can be
useful, depending on the kind of clean up or bookkeeping operations
to perform.

The weak implementation of this function ignores this argument to
preserve platform backwards compatibility.

NOTE: THIS PATCH MAY BREAK PLATFORM PORTS THAT ARE RELYING ON THE
FORMER PROTOTYPE OF THE BL1_PLAT_PREPARE_EXIT() API.

Change-Id: I3fc18f637de06c85719c4ee84c85d6a4572a0fdb

bl1/aarch64/bl1_exceptions.S

@@ -213,6 +213,7 @@ debug_loop:
 	b	debug_loop
 #endif
 
+	mov	x0, x20
 	bl	bl1_plat_prepare_exit
 
 	ldp	x6, x7, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x30)]

docs/porting-guide.md

@@ -810,13 +810,14 @@ represents the entry point system state for BL2.
 
 ### Function : bl1_plat_prepare_exit() [optional]
 
-    Argument : void
+    Argument : entry_point_info_t *
     Return   : void
 
-This function is called prior to exiting BL1 in response to the `RUN_IMAGE_SMC`
+This function is called prior to exiting BL1 in response to the `RUN_IMAGE` SMC
 request raised by BL2. It should be used to perform platform specific clean up
-or bookkeeping operations before transferring control to the next image. This
-function runs with MMU disabled.
+or bookkeeping operations before transferring control to the next image. It
+receives the address of the `entry_point_info_t` structure passed from BL2.
+This function runs with MMU disabled.
 
 
 3.2 Boot Loader Stage 2 (BL2)

plat/common/aarch64/platform_helpers.S

@@ -115,7 +115,7 @@ func plat_disable_acp
 endfunc plat_disable_acp
 
 	/* -----------------------------------------------------
-	 * void bl1_plat_prepare_exit(void);
+	 * void bl1_plat_prepare_exit(entry_point_info_t *ep_info);
 	 * Called before exiting BL1. Default: do nothing
 	 * -----------------------------------------------------
 	 */