ARM: imx: enable big endian mode

Enable ARM big-endian mode on mach-imx. This requires adding some
byte swapping in the debug functions (which otherwise hang forever)
and of course the secondary core bringup.

Tested (on top of 4.4) on i.MX6 HummingBoard quad-core (IMX6Q).

The patch is pretty much as suggested by Arnd Bergmann, thanks!
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/include/debug/imx.S

@@ -11,6 +11,7 @@
  *
  */
 
+#include <asm/assembler.h>
 #include "imx-uart.h"
 
 /*
@@ -34,6 +35,7 @@
 		.endm
 
 		.macro	senduart,rd,rx
+		ARM_BE8(rev \rd, \rd)
 		str	\rd, [\rx, #0x40]	@ TXDATA
 		.endm
 
@@ -42,6 +44,7 @@
 
 		.macro	busyuart,rd,rx
 1002:		ldr	\rd, [\rx, #0x98]	@ SR2
+		ARM_BE8(rev \rd, \rd)
 		tst	\rd, #1 << 3		@ TXDC
 		beq	1002b			@ wait until transmit done
 		.endm

arch/arm/mach-imx/Kconfig

@@ -2,6 +2,7 @@ menuconfig ARCH_MXC
 	bool "Freescale i.MX family"
 	depends on ARCH_MULTI_V4_V5 || ARCH_MULTI_V6_V7 || ARM_SINGLE_ARMV7M
 	select ARCH_REQUIRE_GPIOLIB
+	select ARCH_SUPPORTS_BIG_ENDIAN
 	select ARM_CPU_SUSPEND if PM
 	select CLKSRC_IMX_GPT
 	select GENERIC_IRQ_CHIP

arch/arm/mach-imx/headsmp.S

@@ -12,6 +12,7 @@
 
 #include <linux/linkage.h>
 #include <linux/init.h>
+#include <asm/assembler.h>
 
 diag_reg_offset:
 	.word	g_diag_reg - .
@@ -25,6 +26,7 @@ diag_reg_offset:
 	.endm
 
 ENTRY(v7_secondary_startup)
+ARM_BE8(setend be)			@ go BE8 if entered LE
 	set_diag_reg
 	b	secondary_startup
 ENDPROC(v7_secondary_startup)