libpayload: Provide selfboot function.

The calling convention of payload entry function is different by architecture.
For example, X86 takes no arguments and ARM needs first param to be a
cb_header_ptr*.

To help payloads load and execute other payloads easily and correctly, we should
provide the selfboot() function in libpayload, using same prototype as defined
in coreboot environment.

BUG=none
TEST=emerge-nyan libpayload # pass
BRANCH=none

Original-Change-Id: I8f1cb2c0df788794b2f6f7f5500a3910328a4f84
Original-Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/199503
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 1e916cf021ce68886eb9668982c392eadedc7b7e)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I7279ef27f49ef581d25a455dd8f1f2f7f1ba58cb
Reviewed-on: http://review.coreboot.org/7907
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)

1 files changed, 35 insertions, 0 deletions

diff --git a/payloads/libpayload/arch/arm/selfboot.c b/payloads/libpayload/arch/arm/selfboot.c
new file mode 100644
index 0000000000..cbb7ef1b51
--- /dev/null
+++ b/payloads/libpayload/arch/arm/selfboot.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <libpayload.h>
+
+extern void *cb_header_ptr;
+
+void selfboot(void *entry)
+{
+	__asm__ __volatile__(
+		"mov r0, %[cb_header_ptr]\n"
+		"bx %[entry]\n"
+		:: [cb_header_ptr]"r"(cb_header_ptr), [entry]"r"(entry)
+		: "r0"
+	);
+}