ARM: zynq: Enable the Neon instructions

Added the lowlevel_init to enable the Neon instructions.

Initially the u-boot was causing undefined instruction
exception if loaded through tcl, and working fine if loaded
through FSBL. The exception was causing in convertion formula
of given time to ticks. It was because, the Neon instructions
were disabled and hence causing the undefined exception. In
FSBL case, the FSBL was enabling the Neon instructions. Hence,
added the lowlevel_init to enable the Neon instructions.

Also enable neon instructions for non-xilinx toolchain.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Acked-by: Radhey Shyam Pandey <radheys@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/cpu/armv7/zynq/Makefile

@@ -13,4 +13,5 @@ obj-y	+= cpu.o
 obj-y	+= ddrc.o
 obj-y	+= slcr.o
 obj-y	+= clk.o
+obj-y	+= lowlevel_init.o
 obj-$(CONFIG_SPL_BUILD)	+= spl.o

arch/arm/cpu/armv7/zynq/config.mk

@@ -0,0 +1,7 @@
+#
+# Copyright (C) 2013 - 2015 Xilinx, Inc. All rights reserved.
+#
+# SPDX-License-Identifier:      GPL-2.0
+#
+# Allow NEON instructions (needed for lowlevel_init.S with GNU toolchain)
+PLATFORM_RELFLAGS += -mfpu=neon

arch/arm/cpu/armv7/zynq/cpu.c

@@ -10,9 +10,6 @@
 #include <asm/arch/sys_proto.h>
 #include <asm/arch/hardware.h>
 
-void lowlevel_init(void)
-{
-}
 
 #define ZYNQ_SILICON_VER_MASK	0xF0000000
 #define ZYNQ_SILICON_VER_SHIFT	28

arch/arm/cpu/armv7/zynq/lowlevel_init.S

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2013 Xilinx, Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <asm-offsets.h>
+#include <config.h>
+#include <linux/linkage.h>
+
+ENTRY(lowlevel_init)
+
+	/* Enable the the VFP */
+	mrc	p15, 0, r1, c1, c0, 2
+	orr	r1, r1, #(0x3 << 20)
+	orr	r1, r1, #(0x3 << 20)
+	mcr	p15, 0, r1, c1, c0, 2
+	isb
+	fmrx	r1, FPEXC
+	orr	r1,r1, #(1<<30)
+	fmxr	FPEXC, r1
+
+	/* Move back to caller */
+	mov	pc, lr
+
+ENDPROC(lowlevel_init)