Rationalize reset handling code

The attempt to run the CPU reset code as soon as possible after reset
results in highly complex conditional code relating to the
RESET_TO_BL31 option.

This patch relaxes this requirement a little. In the BL1, BL3-1 and
PSCI entrypoints code, the sequence of operations is now as follows:
 1) Detect whether it is a cold or warm boot;
 2) For cold boot, detect whether it is the primary or a secondary
    CPU. This is needed to handle multiple CPUs entering cold reset
    simultaneously;
 3) Run the CPU init code.

This patch also abstracts the EL3 registers initialisation done by
the BL1, BL3-1 and PSCI entrypoints into common code.

This improves code re-use and consolidates the code flows for
different types of systems.

NOTE: THE FUNCTION plat_secondary_cold_boot() IS NOW EXPECTED TO
NEVER RETURN. THIS PATCH FORCES PLATFORM PORTS THAT RELIED ON THE
FORMER RETRY LOOP AT THE CALL SITE TO MODIFY THEIR IMPLEMENTATION.
OTHERWISE, SECONDARY CPUS WILL PANIC.

Change-Id: If5ecd74d75bee700b1bd718d23d7556b8f863546

1 files changed, 20 insertions, 63 deletions

diff --git a/services/std_svc/psci/psci_entry.S b/services/std_svc/psci/psci_entry.S
index 3f0d4f0c..3f221590 100644
--- a/services/std_svc/psci/psci_entry.S
+++ b/services/std_svc/psci/psci_entry.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2015, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -30,6 +30,7 @@
 
 #include <arch.h>
 #include <asm_macros.S>
+#include <el3_common_macros.S>
 #include <psci.h>
 #include <xlat_tables.h>
 
@@ -52,69 +53,25 @@ psci_aff_suspend_finish_entry:
 	adr	x23, psci_afflvl_suspend_finishers
 
 psci_aff_common_finish_entry:
-#if !RESET_TO_BL31
-	/* ---------------------------------------------
-	 * Perform any processor specific actions which
-	 * undo or are in addition to the actions
-	 * performed by the reset handler in the BootROM
-	 * (BL1) e.g. cache, tlb invalidations, errata
-	 * workarounds etc.
-	 * ---------------------------------------------
-	 */
-	bl      reset_handler
-
-	/* ---------------------------------------------
-	 * Enable the instruction cache, stack pointer
-	 * and data access alignment checks.
-	 * It can be assumed that BL3-1 entrypoint code
-	 * will do this when RESET_TO_BL31 is set. The
-	 * same  assumption cannot be made when another
-	 * boot loader executes before BL3-1 in the warm
-	 * boot path e.g. BL1.
-	 * ---------------------------------------------
-	 */
-	mov	x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
-	mrs	x0, sctlr_el3
-	orr	x0, x0, x1
-	msr	sctlr_el3, x0
-	isb
-#endif
-
-	/* ---------------------------------------------
-	 * Initialise the pcpu cache pointer for the CPU
-	 * ---------------------------------------------
-	 */
-	bl	init_cpu_data_ptr
-
-	/* ---------------------------------------------
-	 * Set the exception vectors
-	 * ---------------------------------------------
-	 */
-	adr	x0, runtime_exceptions
-	msr	vbar_el3, x0
-	isb
-
-	/* ---------------------------------------------
-	 * Enable the SError interrupt now that the
-	 * exception vectors have been setup.
-	 * ---------------------------------------------
-	 */
-	msr	daifclr, #DAIF_ABT_BIT
-
-	/* ---------------------------------------------
-	 * Use SP_EL0 for the C runtime stack.
-	 * ---------------------------------------------
-	 */
-	msr	spsel, #0
-
-	/* --------------------------------------------
-	 * Give ourselves a stack whose memory will be
-	 * marked as Normal-IS-WBWA when the MMU is
-	 * enabled.
-	 * --------------------------------------------
+	/*
+	 * On the warm boot path, most of the EL3 initialisations performed by
+	 * 'el3_entrypoint_common' must be skipped:
+	 *
+	 *  - No need to determine the type of boot, we know it is a warm boot.
+	 *
+	 *  - Do not try to distinguish between primary and secondary CPUs, this
+	 *    notion only exists for a cold boot.
+	 *
+	 *  - No need to initialise the memory or the C runtime environment,
+	 *    it has been done once and for all on the cold boot path.
 	 */
-	mrs	x0, mpidr_el1
-	bl	platform_set_stack
+	el3_entrypoint_common					\
+		_set_endian=0					\
+		_warm_boot_mailbox=0				\
+		_secondary_cold_boot=0				\
+		_init_memory=0					\
+		_init_c_runtime=0				\
+		_exception_vectors=runtime_exceptions
 
 	/* --------------------------------------------
 	 * Enable the MMU with the DCache disabled. It