Staging: add Synaptics RMI4 touchpad driver support

Added the Synaptics RMI4 touchpad driver support.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Naveen Kumar Gaddipati <naveen.gaddipati@stericsson.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christopher Heiny <cheiny@synaptics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/Kconfig

@@ -177,5 +177,7 @@ source "drivers/staging/speakup/Kconfig"
 
 source "drivers/staging/cptm1217/Kconfig"
 
+source "drivers/staging/ste_rmi4/Kconfig"
+
 endif # !STAGING_EXCLUDE_BUILD
 endif # STAGING

drivers/staging/Makefile

@@ -69,3 +69,4 @@ obj-$(CONFIG_FT1000)		+= ft1000/
 obj-$(CONFIG_SND_INTEL_SST)		+= intel_sst/
 obj-$(CONFIG_SPEAKUP)	+= speakup/
 obj-$(CONFIG_TOUCHSCREEN_CLEARPAD_TM1217)	+= cptm1217/
+obj-$(CONFIG_TOUCHSCREEN_SYNAPTICS_I2C_RMI4)	+= ste_rmi4/

drivers/staging/ste_rmi4/Kconfig

@@ -0,0 +1,9 @@
+config TOUCHSCREEN_SYNAPTICS_I2C_RMI4
+	tristate "Synaptics i2c rmi4 touchscreen"
+	depends on I2C
+	help
+	  Say Y here if you have a Synaptics RMI4 and
+	  want to enable support for the built-in touchscreen.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called synaptics_rmi4_ts.

drivers/staging/ste_rmi4/Makefile

@@ -0,0 +1,4 @@
+#
+# Makefile for the RMI4 touchscreen driver.
+#
+obj-$(CONFIG_TOUCHSCREEN_SYNAPTICS_I2C_RMI4) += synaptics_i2c_rmi4.o

drivers/staging/ste_rmi4/TODO

@@ -0,0 +1,7 @@
+TODO
+----
+
+Wait for the official upstream synaptics rmi4 clearpad drivers as promised over the past few months
+Merge any device support needed from this driver into it
+Delete this driver
+