serial: mxs-auart: add Alphascale ASM9260 support

Alphascale ASM9260 uart IP has some common registers with
Freescale STMP37XX. This patch provide changes which
allow to reuse mxs-auart.c code for ASM9260.
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt

 * Freescale MXS Application UART (AUART)
 
-Required properties:
-- compatible : Should be "fsl,<soc>-auart". The supported SoCs include
-  imx23 and imx28.
+Required properties for all SoCs:
+- compatible : Should be one of fallowing variants:
+	"fsl,imx23-auart" - Freescale i.MX23
+	"fsl,imx28-auart" - Freescale i.MX28
+	"alphascale,asm9260-auart" - Alphascale ASM9260
 - reg : Address and length of the register set for the device
 - interrupts : Should contain the auart interrupt numbers
 - dmas: DMA specifier, consisting of a phandle to DMA controller node
@@ -10,6 +12,12 @@ Required properties:
   Refer to dma.txt and fsl-mxs-dma.txt for details.
 - dma-names: "rx" for RX channel, "tx" for TX channel.
 
+Required properties for "alphascale,asm9260-auart":
+- clocks : the clocks feeding the watchdog timer. See clock-bindings.txt
+- clock-names : should be set to
+	"mod" - source for tick counter.
+	"ahb" - ahb gate.
+
 Optional properties:
 - fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines
   for hardware flow control,

drivers/tty/serial/Kconfig

@@ -1384,11 +1384,12 @@ config SERIAL_PCH_UART_CONSOLE
 config SERIAL_MXS_AUART
 	tristate "MXS AUART support"
 	depends on HAS_DMA
-	depends on ARCH_MXS || COMPILE_TEST
+	depends on ARCH_MXS || MACH_ASM9260 || COMPILE_TEST
 	select SERIAL_CORE
 	select SERIAL_MCTRL_GPIO if GPIOLIB
 	help
-	  This driver supports the MXS Application UART (AUART) port.
+	  This driver supports the MXS and Alphascale ASM9260 Application
+	  UART (AUART) port.
 
 config SERIAL_MXS_AUART_CONSOLE
 	bool "MXS AUART console support"