Input: add driver for Hynitron cstxxx touchscreens

Add support for the Hynitron cst3xx controller found on devices such
as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver
was built from sources provided by Hynitron to Anbernic (possibly
via Rockchip as an intermediary) and marked as GPLv2 in the code.
This driver was written strictly for the cst3xx series, but in
most places was left somewhat generic so support could be easily
added to other devices in the future.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20221028202636.14341-4-macroalpha82@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/Kconfig

@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 
+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C
+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile

@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o