Input: add Himax HX852x(ES) touchscreen driver

Add a simple driver for the Himax HX852x(ES) touch panel controller,
with support for multi-touch and capacitive touch keys.

The driver is somewhat based on sample code from Himax. However, that
code was rather confusing, so that we spent a significant amount of
time just trying to understand the packet format and register commands.
In this driver they are described with clean structs and defines rather
than magic numbers and offset calculations.

Co-developed-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Reviewed-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20250915-hx852x-v5-2-b938182f1056@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: stephan-gh

MAINTAINERS

@@ -10965,6 +10965,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/input/touchscreen/himax,hx83112b.yaml
 F:	drivers/input/touchscreen/himax_hx83112b.c
 
+HIMAX HX852X TOUCHSCREEN DRIVER
+M:	Stephan Gerhold <stephan@gerhold.net>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/himax,hx852es.yaml
+F:	drivers/input/touchscreen/himax_hx852x.c
+
 HIPPI
 M:	Jes Sorensen <jes@trained-monkey.org>
 S:	Maintained

drivers/input/touchscreen/Kconfig

@@ -441,6 +441,16 @@ config TOUCHSCREEN_HIDEEP
 	  To compile this driver as a module, choose M here : the
 	  module will be called hideep_ts.
 
+config TOUCHSCREEN_HIMAX_HX852X
+	tristate "Himax HX852x(ES) touchscreen"
+	depends on I2C
+	help
+	  Say Y here if you have a Himax HX852x(ES) touchscreen.
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called himax_hx852x.
+
 config TOUCHSCREEN_HYCON_HY46XX
 	tristate "Hycon hy46xx touchscreen support"
 	depends on I2C

drivers/input/touchscreen/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_CORE)	+= goodix_berlin_core.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_I2C)	+= goodix_berlin_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_SPI)	+= goodix_berlin_spi.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HIMAX_HX852X)	+= himax_hx852x.o
 obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o