ARM: imx6: Add UART2 for low-level debug

To be able to enable early debugging on boards using the UART2 for the
console, add the option for early debugging on UART2.
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/Kconfig.debug

@@ -180,6 +180,14 @@ choice
 		  Say Y here if you want kernel low-level debugging support
 		  on i.MX50 or i.MX53.
 
+	config DEBUG_IMX6Q_UART2
+		bool "i.MX6Q Debug UART2"
+		depends on SOC_IMX6Q
+		help
+		  Say Y here if you want kernel low-level debugging support
+		  on i.MX6Q UART2. This is correct for e.g. the SabreLite
+                  board.
+
 	config DEBUG_IMX6Q_UART4
 		bool "i.MX6Q Debug UART4"
 		depends on SOC_IMX6Q

arch/arm/mach-imx/lluart.c

@@ -17,6 +17,12 @@
 #include <mach/hardware.h>
 
 static struct map_desc imx_lluart_desc = {
+#ifdef CONFIG_DEBUG_IMX6Q_UART2
+	.virtual	= MX6Q_IO_P2V(MX6Q_UART2_BASE_ADDR),
+	.pfn		= __phys_to_pfn(MX6Q_UART2_BASE_ADDR),
+	.length		= MX6Q_UART2_SIZE,
+	.type		= MT_DEVICE,
+#endif
 #ifdef CONFIG_DEBUG_IMX6Q_UART4
 	.virtual	= MX6Q_IO_P2V(MX6Q_UART4_BASE_ADDR),
 	.pfn		= __phys_to_pfn(MX6Q_UART4_BASE_ADDR),

arch/arm/plat-mxc/include/mach/debug-macro.S

@@ -24,6 +24,8 @@
 #define UART_PADDR	MX51_UART1_BASE_ADDR
 #elif defined (CONFIG_DEBUG_IMX50_IMX53_UART)
 #define UART_PADDR	MX53_UART1_BASE_ADDR
+#elif defined (CONFIG_DEBUG_IMX6Q_UART2)
+#define UART_PADDR	MX6Q_UART2_BASE_ADDR
 #elif defined (CONFIG_DEBUG_IMX6Q_UART4)
 #define UART_PADDR	MX6Q_UART4_BASE_ADDR
 #endif

arch/arm/plat-mxc/include/mach/mx6q.h

@@ -27,6 +27,8 @@
 #define MX6Q_CCM_SIZE			0x4000
 #define MX6Q_ANATOP_BASE_ADDR		0x020c8000
 #define MX6Q_ANATOP_SIZE		0x1000
+#define MX6Q_UART2_BASE_ADDR		0x021e8000
+#define MX6Q_UART2_SIZE			0x4000
 #define MX6Q_UART4_BASE_ADDR		0x021f0000
 #define MX6Q_UART4_SIZE			0x4000