Input: add Imagis touchscreen driver

Add support for the IST3038C touchscreen IC from Imagis, based on
downstream driver. The driver supports multi-touch (10 touch points)
The IST3038C IC supports touch keys, but the support isn't added
because the touch screen used for testing doesn't utilize touch keys.
Looking at the downstream driver, it is possible to add support
for other Imagis ICs of IST30**C series.

Reviewed-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
Link: https://lore.kernel.org/r/20220305165330.13061-3-markuss.broks@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

MAINTAINERS

@@ -9370,6 +9370,12 @@ M:	Stanislaw Gruszka <stf_xl@wp.pl>
 S:	Maintained
 F:	drivers/usb/atm/ueagle-atm.c
 
+IMAGIS TOUCHSCREEN DRIVER
+M:	Markuss Broks <markuss.broks@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
+F:	drivers/input/touchscreen/imagis.c
+
 IMGTEC ASCII LCD DRIVER
 M:	Paul Burton <paulburton@kernel.org>
 S:	Maintained

drivers/input/touchscreen/Kconfig

@@ -638,6 +638,16 @@ config TOUCHSCREEN_MTOUCH
 	  To compile this driver as a module, choose M here: the
 	  module will be called mtouch.
 
+config TOUCHSCREEN_IMAGIS
+	tristate "Imagis touchscreen support"
+	depends on I2C
+	help
+	  Say Y here if you have an Imagis IST30xxC touchscreen.
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called imagis.
+
 config TOUCHSCREEN_IMX6UL_TSC
 	tristate "Freescale i.MX6UL touchscreen controller"
 	depends on ((OF && GPIOLIB) || COMPILE_TEST) && HAS_IOMEM

drivers/input/touchscreen/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
+obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o
 obj-$(CONFIG_TOUCHSCREEN_IMX6UL_TSC)	+= imx6ul_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_INEXIO)	+= inexio.o
 obj-$(CONFIG_TOUCHSCREEN_IPROC)		+= bcm_iproc_tsc.o