arm64: use one stage_entry for all stages

Ramstage needs an assembly entry point for setting up
the initial state of the CPU. Therefore, a function is
provided, arm64_el3_startup(), that bootstraps the state
of the processor, initializes the stack pointer, and
branches to a defined entry symbol. To make this work
without adding too much preprocessor macro conditions
provide _stack and _estack for all the stages.

Currently the entry point after initialization is 'main',
however it can be changed/extended to do more work such
as seeding the stack contents with tombstones, etc.

It should be noted that romstage and bootblock weren't
tested. Only ramstage is known to work.

BUG=chrome-os-partner:29923
BRANCH=None
TEST=Brought up 64-bit ramstage on rush.

Original-Change-Id: I1f07d5b6656e13e6667b038cdc1f4be8843d1960
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/207262
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit 7850ee3a7bf48c05f2e64147edb92161f8308f19)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Ia87697f49638c8c249215d441d95f1ec621e0949
Reviewed-on: http://review.coreboot.org/8585
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/src/arch/arm64/stage_entry.S b/src/arch/arm64/stage_entry.S
new file mode 100644
index 0000000000..56eca77aae
--- /dev/null
+++ b/src/arch/arm64/stage_entry.S
@@ -0,0 +1,57 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+#include <arch/asm.h>
+
+ENTRY(arm64_el3_startup)
+	mov	x0, xzr
+	msr	SCTLR_EL3, x0
+	msr	SCR_EL3, x0
+	/* Have stack pointer use SP_EL0. */
+	msr	SPSel, #0
+	isb
+
+	/* Load up the stack if non-zero. */
+	ldr	x0, .stack
+	cmp	x0, #0
+	b.eq	1f
+	mov	sp, x0
+	1:
+
+	ldr	x1, .entry
+	br	x1
+
+	.align 4
+	/*
+	 * By default branch to main() and initialize the stack according
+	 * to the Kconfig option for cpu0. However, this code can be relocated
+	 * and reused to start up secondary cpus.
+	 */
+	.stack:
+		.quad _estack
+	.entry:
+		.quad main
+ENDPROC(arm64_el3_startup)
+.global arm64_el3_startup_end
+arm64_el3_startup_end:
+
+ENTRY(stage_entry)
+	b	arm64_el3_startup
+ENDPROC(stage_entry)