board: arm: Add support for Broadcom BCM7445

Add support for loading U-Boot on the Broadcom 7445 SoC.  This port
assumes Broadcom's BOLT bootloader is acting as the second stage
bootloader, and U-Boot is acting as the third stage bootloader, loaded
as an ELF program by BOLT.

Signed-off-by: Thomas Fitzsimmons <fitzsim@fitzsim.org>
Cc: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/arch/arm/mach-bcmstb/lowlevel_init.S b/arch/arm/mach-bcmstb/lowlevel_init.S
new file mode 100644
index 0000000..aa81f70
--- /dev/null
+++ b/arch/arm/mach-bcmstb/lowlevel_init.S
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2018  Cisco Systems, Inc.
+ *
+ * Author: Thomas Fitzsimmons <fitzsim@fitzsim.org>
+ */
+
+#include <linux/linkage.h>
+
+ENTRY(save_boot_params)
+	ldr	r6, =bcmstb_boot_parameters
+	str	r0, [r6, #0]
+	str	r1, [r6, #4]
+	str	r2, [r6, #8]
+	str	r3, [r6, #12]
+	str	sp, [r6, #16]
+	str	lr, [r6, #20]
+	ldr	r6, =prior_stage_fdt_address
+	str	r2, [r6]
+	b	save_boot_params_ret
+ENDPROC(save_boot_params)