I.MX6 Goodix GT9xx touchscreen driver porting

/************************************************************************
 *          I.MX6 Goodix GT9xx touchscreen driver porting
 * 声明：
 *     本文主要是记录GT9xx电容Touch移植过程中遇到的一些问题。
 *
 *                                      2016-1-27 深圳 南山平山村 曾剑锋
 ***********************************************************************/

一、参考文档：
    GT9XX驱动移植说明书_for_Android_2014011401.pdf

二、error :
    . 出错信息：
        . 直接将驱动放在kernel里系统会卡死，出错信息如下：
            USB Gadget resume begins
            fsl_udc_resume, Wait for wakeup thread finishes
            dr_controller_run: udc out low power mode
            USB Gadget resume ends
            fsl-usb2-udc: bind to driver android_usb
            mousedev: PS/ mouse device common for all mice
            input: gpio-keys as /devices/platform/gpio-keys/input/input0
            <<-GTP-INFO->> GTP driver installing...
            <<-GTP-INFO->> GTP Driver Version: V2.<//>
            <<-GTP-INFO->> GTP Driver Built@::, Jan
            <<-GTP-INFO->> GTP I2C Address: 0x5d
            <<-GTP-INFO->> Guitar reset
            <<-GTP-INFO->> Chip Type: GOODIX_GT9
            <<-GTP-INFO->> IC Version: 9157_1040
            <<-GTP-INFO->> X_MAX: , Y_MAX: , TRIGGER: 0x01
            <<-GTP-INFO->> create proc entry gt9xx_config success
            input: goodix-ts as /devices/virtual/input/input1
            <<-GTP-INFO->> GTP works in interrupt mode.
            <<-GTP-INFO->> Applied memory size:.
            <<-GTP-INFO->> Applied memory size:.
            <<-GTP-INFO->> I2C function: without pre and end cmd!
            <<-GTP-INFO->> Create proc entry success!
            mtk_tpd: hotknot_device register failed
            USB Gadget resume begins
            fsl_udc_resume, Wait for wakeup thread finishes
            ehci_fsl_bus_suspend begins, Host
            ehci_fsl_bus_suspend ends, Host
            <系统会卡死在这里，接下来没有任何信息输出>
        . 作为模块加入内核，使用久了，系统也会卡死：
            root@android:/ # cd /data/local
            root@android:/data/local # ls
            gt9xxm.ko
            tmp
            root@android:/data/local # insmod gt9xxm.ko
            <<-GTP-INFO->> GTP driver installing...
            <<-GTP-INFO->> GTP Driver Version: V2.<//>
            <<-GTP-INFO->> GTP Driver Built@::, Jan
            <<-GTP-INFO->> GTP I2C Address: 0x5d
            <<-GTP-INFO->> Guitar reset
            <<-GTP-INFO->> Chip Type: GOODIX_GT9
            <<-GTP-INFO->> IC Version: 9157_1040
            <<-GTP-INFO->> X_MAX: , Y_MAX: , TRIGGER: 0x01
            <<-GTP-INFO->> create proc entry gt9xx_config success
            input: goodix-ts as /devices/virtual/input/input1
            cpufreq_interactive_input_connect: connect to goodix-ts
            <<-GTP-INFO->> GTP works in interrupt mode.
            <<-GTP-INFO->> Applied memory size:.
            <<-GTP-INFO->> Applied memory size:.
            <<-GTP-INFO->> I2C function: without pre and end cmd!
            root@android:/data/local # <<-GTP-INFO->> Create proc entry success!
            mtk_tpd: hotknot_device register failed
    . 解决方法：
        . cat gt9xx.h
            ......
            #define HOTKNOT_ENABLE        0    // hotknot module
            #define HOTKNOT_BLOCK_RW      0    // block rw operation in hotknot
            ......
        . cat goodix_tool.c
            s32 init_wr_node(struct i2c_client *client)
            {
                ......
            #if 0
                if (misc_register(&hotknot_misc_device))
                {
                      printk("mtk_tpd: hotknot_device register failed\n");
                      return FAIL;
                }
            #endif
                ......
            }
    . 思路来源：
        . 想通过尽可能减少驱动的功能来判断驱动哪里出了问题。
        . cat gt9xx.h
            ......
            #define HOTKNOT_ENABLE        1    // hotknot module
            #define HOTKNOT_BLOCK_RW      1    // block rw operation in hotknot
            ......
        . 如上所述，不需要该功能，当然我也不知道这是什么功能。
        . 改为如下内容：
            #define HOTKNOT_ENABLE        0    // hotknot module
            #define HOTKNOT_BLOCK_RW      0    // block rw operation in hotknot
        . 报错如下：
            ......
              CC      drivers/input/touchscreen/gt9xx.o
            drivers/input/touchscreen/gt9xx.c: In function 'goodix_ts_suspend':
            drivers/input/touchscreen/gt9xx.c::: warning: unused variable 'buf' [-Wunused-variable]
              CC      drivers/input/touchscreen/gt9xx_update.o
              CC      drivers/input/touchscreen/goodix_tool.o
            drivers/input/touchscreen/goodix_tool.c: In function 'init_wr_node':
            drivers/input/touchscreen/goodix_tool.c::: error: 'hotknot_misc_device' undeclared (first use in this function)
            drivers/input/touchscreen/goodix_tool.c::: note: each undeclared identifier is reported only once for each function it appears in
            drivers/input/touchscreen/goodix_tool.c: At top level:
            drivers/input/touchscreen/goodix_tool.c::: warning: 'hotknot_write' defined but not used [-Wunused-function]
            drivers/input/touchscreen/goodix_tool.c::: warning: 'hotknot_read' defined but not used [-Wunused-function]
            make[]: *** [drivers/input/touchscreen/goodix_tool.o] Error
            make[]: *** [drivers/input/touchscreen] Error
            make[]: *** [drivers/input] Error
            make: *** [drivers] Error
            error: make uImage failed.
            ./remake.sh: : exit: Illegal number: -
        . 既然已经禁止了，那么不可能还有hotknot_misc_device设备注册的，也就意味着这个版本的驱动有错。
        . 综上所述：可能是我们的kernel不支持hotknot这个功能导致的。

三、error :
    . 触摸屏点击有效，但是不准确，TP厂没有给矫正文件，后来FAE确认是由于矫正配置参数的问题。
    . 修改gt9xx.h文件：
        ......
        #define GTP_DRIVER_SEND_CFG   1
        ......
    . 配置参数：
        #define CTP_CFG_GROUP0 {\
            0x46,0xD0,0x02,0x00,0x05,0x0A,0x05,0x40,0x01,0x08,\
            0x28,0x0F,0x50,0x32,0x03,0x05,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x8A,0x0A,0x0B,\
            0x2E,0x30,0x31,0x0D,0x00,0x00,0x00,0x02,0x03,0x1D,\
            0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x32,0x00,0x00,\
            0x00,0x21,0x41,0x94,0xC5,0x02,0x07,0x00,0x00,0x04,\
            0x9E,0x23,0x00,0x8D,0x28,0x00,0x80,0x2E,0x00,0x74,\
            0x35,0x00,0x69,0x3C,0x00,0x69,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x16,0x14,0x12,0x10,0x0E,0x0C,0x0A,0x08,\
            0x06,0x04,0x02,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,\
            0x00,0x00,0x16,0x13,0x18,0x12,0x1C,0x10,0x1D,0x0F,\
            0x0A,0x1E,0x00,0x24,0x22,0x02,0x21,0x04,0x20,0x06,\
            0x1F,0x08,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00,0x00,\
            0x00,0xFB,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,\
            0x9F,0xFF,0xFF,0xFF,0x00,0x01\
            }