ARM: imx: add low-level debug for vybrid

Add low-level debug support for vybrid, so that earlyprintk can be
enabled for debugging early boot issue.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/Kconfig.debug

@@ -386,6 +386,13 @@ choice
 		  when u-boot hands over to the kernel, the system
 		  silently crashes, with no serial output at all.
 
+	config DEBUG_VF_UART
+		bool "Vybrid UART"
+		depends on SOC_VF610
+		help
+		  Say Y here if you want kernel low-level debugging support
+		  on Vybrid based platforms.
+
 	config DEBUG_NOMADIK_UART
 		bool "Kernel low-level debugging messages via NOMADIK UART"
 		depends on ARCH_NOMADIK
@@ -906,6 +913,7 @@ config DEBUG_LL_INCLUDE
 	default "debug/tegra.S" if DEBUG_TEGRA_UART
 	default "debug/ux500.S" if DEBUG_UX500_UART
 	default "debug/vexpress.S" if DEBUG_VEXPRESS_UART0_DETECT
+	default "debug/vf.S" if DEBUG_VF_UART
 	default "debug/vt8500.S" if DEBUG_VT8500_UART0
 	default "debug/zynq.S" if DEBUG_ZYNQ_UART0 || DEBUG_ZYNQ_UART1
 	default "mach/debug-macro.S"

arch/arm/include/debug/vf.S

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+	.macro	addruart, rp, rv, tmp
+	ldr	\rp, =0x40028000	@ physical
+	ldr	\rv, =0xfe028000	@ virtual
+	.endm
+
+	.macro	senduart, rd, rx
+	strb	\rd, [\rx, #0x7]	@ Data Register
+	.endm
+
+	.macro	busyuart, rd, rx
+1001:	ldrb	\rd, [\rx, #0x4]	@ Status Register 1
+	tst	\rd, #1 << 6		@ TC
+	beq	1001b			@ wait until transmit done
+	.endm
+
+	.macro	waituart,rd,rx
+	.endm