serial: msm_serial_hs: Add MSM high speed UART driver

This driver supports UART-DM HW on MSM platforms. It uses the on
chip DMA to drive data transfers and has optional support for UART
power management independent of Linux suspend/resume and wakeup
from Rx.

The driver was originally developed by Google. It is functionally
equivalent to the version available at:
http://android.git.kernel.org/?p=kernel/experimental.git
the differences being:
1) Remove wakelocks and change unsupported DMA API.
2) Replace clock selection register codes by macros.
3) Fix checkpatch errors and add inline documentation.
4) Add runtime PM hooks for active power state transitions.
5) Handle error path and cleanup resources if required.

CC: Nick Pelly <npelly@google.com>
Signed-off-by: Sankalp Bose <sankalpb@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/Kconfig

@@ -1319,6 +1319,18 @@ config SERIAL_MSM_CONSOLE
 	depends on SERIAL_MSM=y
 	select SERIAL_CORE_CONSOLE
 
+config SERIAL_MSM_HS
+	tristate "MSM UART High Speed: Serial Driver"
+	depends on ARCH_MSM
+	select SERIAL_CORE
+	help
+	  If you have a machine based on MSM family of SoCs, you
+	  can enable its onboard high speed serial port by enabling
+	  this option.
+
+	  Choose M here to compile it as a module. The module will be
+	  called msm_serial_hs.
+
 config SERIAL_VT8500
 	bool "VIA VT8500 on-chip serial port support"
 	depends on ARM && ARCH_VT8500

drivers/tty/serial/Makefile

@@ -76,6 +76,7 @@ obj-$(CONFIG_SERIAL_SGI_IOC3) += ioc3_serial.o
 obj-$(CONFIG_SERIAL_ATMEL) += atmel_serial.o
 obj-$(CONFIG_SERIAL_UARTLITE) += uartlite.o
 obj-$(CONFIG_SERIAL_MSM) += msm_serial.o
+obj-$(CONFIG_SERIAL_MSM_HS) += msm_serial_hs.o
 obj-$(CONFIG_SERIAL_NETX) += netx-serial.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL) += nwpserial.o