android_kernel_samsung_sm8650-modules/docs/Porting_Guide.md

Berlin Driver Porting Guide

Introduce

Berlin series driver is currently support BerlinA(GT9897), BerlinB(GT9966, GT7986). And support I2C or SPI connection.

Driver source file prepare

1. Move driver source code to $KERNEL_SRC/drivers/input/touchscree/

2. Change $KERNEL_SRC/drivers/input/touchscree/Makefile
   Add this line to the Makefile

   obj-y += goodix_berlin_driver/
   

3. Change $KERNEL_SRC/drivers/input/touchscree/Kconfg
   Add this line to the Kconfig

   source "drivers/input/touchscreen/goodix_berlin_driver/Kconfig"
   

Add device declaration in the board devicetree

Please add Goodix touch device declaration info in the board devicetree, you can refer the Appendix goodix-ts-i2c-dtsi or goodix-ts-spi-dtsi to see how to set deivce properties.

Build driver

When build kernel you will see the following promt to let you confirm how to build the driver. This driver support built-in kernel or build as modules.

Setting up in the menu:

1. In the $KERNEL_SRC directory, exec make menuconfig, then select
   Device Drivers ---> Input device support ---> Touchscreens --->
   
2. Find Goodix berlin touchscreen menu, you can select <*>(build in kernel) or <M>(build a module).
3. Enter Goodix berlin touchscreen, you can see support SPI bus connection item. If you are on SPI connection, select <*>, or on I2C connection.

Setting up in the defconfig file:

1. Add the following in you defconfig file.

   CONFIG_TOUCHSCREEN_GOODIX_BRL=y
   

   or

   CONFIG_TOUCHSCREEN_GOODIX_BRL=m
   

2. If you are on SPI connection, add the following.

   CONFIG_TOUCHSCREEN_GOODIX_BRL_SPI=y
   

Appendix

goodix-ts-i2c-dtsi

devicetree binding for Goodix i2c touchdriver
Required properties:
- compatible: device & driver matching.
	* for berlin series touch device, souch as "goodix,gt9897", "goodix,gt9966"

- reg: i2c client address, value can be 0x14 or 0x5d. please refer to datasheet.
- goodix,reset-gpio: reset gpio.
- goodix,irq-gpio: interrupt gpio. 
- goodix,irq-flags: irq trigger type config, value should be:
	       1 - rising edge,
	       2 - falling edge,
	       4 - high level,
	       5 - low level.
- goodix,panel-max-x: max resolution of x direction.
- goodix,panel-max-y: max resolution of y direction.
- goodix,panel-max-w: panel max width value.
- goodix,panel-max-p: pen device max pressure value.

Optional properties:
- goodix,avdd-name: set name of regulator.
- avdd-supply: power supply for the touch device.
  example of regulator:
	goodix,avdd-name = "avdd";
	avdd-supply = <&pm8916_l15>;
- iovdd-supply: power supply for digital io circuit
  example of regulator:
	goodix,iovdd-name = "iovdd";
	iovdd-supply = <&pm8916_l16>;
- goodix,pen-enable: set this property if you want support stylus.
	goodix,pen-enable;
- goodix,firmware-name: set firmware file name, if not configured, use the default name.
- goodix,config-name: set config file name, if not configured, use the default name.
Example 1:
goodix-berlin@5d {
	compatible = "goodix,gt9897";
	reg = <0x5d>;
	goodix,reset-gpio = <&msm_gpio 12 0x0>;
	goodix,irq-gpio = <&msm_gpio 13 0x2800>;
	goodix,irq-flags = <2>; /* 1:trigger rising, 2:trigger falling;*/
	goodix,panel-max-x = <720>;
	goodix,panel-max-y = <1280>;
	goodix,panel-max-w = <255>;
};

Example 2:
goodix-berlin@5d {
	compatible = "goodix,gt9966";
	goodix,avdd-name = "avdd";
	avdd-supply = <&pm8916_l15>;
	goodix,iovdd-name = "iovdd";
	iovdd-supply = <&pm8916_l16>;

	reg = <0x5d>;
	goodix,reset-gpio = <&msm_gpio 12 0x0>;
	goodix,irq-gpio = <&msm_gpio 13 0x2800>;
	goodix,irq-flags = <2>; /* 1:trigger rising, 2:trigger falling;*/
	goodix,panel-max-x = <720>;
	goodix,panel-max-y = <1280>;
	goodix,panel-max-w = <255>;
	goodix,panel-max-p = <4096>; /* max pressure that pen device supported */
	goodix,pen-enable; /* support active stylus device*/

	goodix,firmware-name = "goodix_firmware.bin";
	goodix,config-name = "goodix_cfg_group.bin";
};

goodix-ts-spi-dtsi

devicetree binding for Goodix spi touchdriver

Required properties:
- compatible: device & driver matching.
	* for berlin series touch device, souch as "goodix,gt9897T"

- spi-max-frequency: set spi transfer speed.
- reg: depend on CS gpio.
- goodix,reset-gpio: reset gpio.
- goodix,irq-gpio: interrupt gpio.
- goodix,irq-flags: irq trigger type config, value should be:
	       1 - rising edge,
	       2 - falling edge,
	       4 - high level,
	       5 - low level.
- goodix,panel-max-x: max resolution of x direction.
- goodix,panel-max-y: max resolution of y direction.
- goodix,panel-max-w: panel max width value.
- goodix,panel-max-p: pen device max pressure value.

Optional properties:
- goodix,avdd-name: set name of regulator.
- avdd-supply: power supply for the touch device.
  example of regulator:
	goodix,avdd-name = "avdd";
	avdd-supply = <&pm8916_l15>;
- iovdd-supply: power supply for digital io circuit
  example of regulator:
	goodix,iovdd-name = "iovdd";
	iovdd-supply = <&pm8916_l16>;
- goodix,pen-enable: set this property if you want support stylus.
	goodix,pen-enable;
- goodix,firmware-name: set firmware file name, if not configured, use the default name.
- goodix,config-name: set config file name, if not configured, use the default name.	
Example 1:
goodix-berlin@0 {
	compatible = "goodix,gt9897";
	reg = <0>;
	spi-max-frequency = <1000000>;
	goodix,reset-gpio = <&msm_gpio 12 0x0>;
	goodix,irq-gpio = <&msm_gpio 13 0x2800>;
	goodix,irq-flags = <2>; /* 1:trigger rising, 2:trigger falling;*/
	goodix,panel-max-x = <720>;
	goodix,panel-max-y = <1280>;
	goodix,panel-max-w = <255>;
};

Example 2:
goodix-berlin@0 {
	compatible = "goodix,gt9966S";
	reg = <0>;
	spi-max-frequency = <1000000>;

	goodix,avdd-name = "avdd";
	avdd-supply = <&pm8916_l15>;
	goodix,iovdd-name = "iovdd";
	iovdd-supply = <&pm8916_l16>;

	goodix,reset-gpio = <&msm_gpio 12 0x0>;
	goodix,irq-gpio = <&msm_gpio 13 0x2800>;
	goodix,irq-flags = <2>; /* 1:trigger rising, 2:trigger falling;*/
	goodix,panel-max-x = <720>;
	goodix,panel-max-y = <1280>;
	goodix,panel-max-w = <255>;
	goodix,panel-max-p = <4096>; /* max pressure that pen device supported */
	goodix,pen-enable; /* support active stylus device*/

	goodix,firmware-name = "goodix_firmware.bin";
	goodix,config-name = "goodix_cfg_group.bin";	
};