drivers/input: Add driver for Goodix GT9XX Touch Panel

This PR adds the driver for Goodix GT9XX I2C Touch Panel, which will be called by PINE64 PinePhone.

Our driver follows the design of the NuttX Driver for [Cypress MBR3108](https://github.com/apache/nuttx/blob/master/drivers/input/cypress_mbr3108.c).

We have documented our driver here: ["NuttX Touch Panel Driver for PinePhone"](https://lupyuen.github.io/articles/touch2#appendix-nuttx-touch-panel-driver-for-pinephone)

`drivers/input/Kconfig`: Added option `INPUT_GT9XX` to select GT9XX Driver

`drivers/input/Make.defs`: Added GT9XX Driver to Makefile

`drivers/input/gt9xx.c`, `gt9xx.h`: I2C Driver for GT9XX Touch Panel

drivers/input/Kconfig

@@ -499,6 +499,29 @@ config INPUT_CYPRESS_MBR3108_NPOLLWAITERS
 
 endif # INPUT_CYPRESS_MBR3108
 
+config INPUT_GT9XX
+	bool "Goodix GT9xx Driver"
+	default n
+	select INPUT_TOUCHSCREEN
+	---help---
+		Enable support for Goodix GT9xx touch panel.
+
+if INPUT_GT9XX
+
+config INPUT_GT9XX_NPOLLWAITERS
+	int "Number of waiters to poll"
+	default 1
+	---help---
+		Maximum number of threads that can be waiting on poll()
+
+config INPUT_GT9XX_I2C_FREQUENCY
+	int "I2C frequency (Hz)"
+	default 400000
+	---help---
+		I2C frequency in Hz
+
+endif # INPUT_GT9XX
+
 config INPUT_BUTTONS
 	bool "Button Inputs"
 	default n

drivers/input/Make.defs

@@ -72,6 +72,10 @@ ifeq ($(CONFIG_INPUT_CYPRESS_MBR3108),y)
   CSRCS += cypress_mbr3108.c
 endif
 
+ifeq ($(CONFIG_INPUT_GT9XX),y)
+  CSRCS += gt9xx.c
+endif
+
 ifeq ($(CONFIG_INPUT_BUTTONS),y)
   CSRCS += button_upper.c
 ifeq ($(CONFIG_INPUT_BUTTONS_LOWER),y)