ft6236 觸摸屏驅動

在目錄下amp\a53_linux\drv\extdrv\touchpad\ft6236下可以看到ft6236.c的文件

1. init函數

static int __init ft_init(void)
{
    int ret = 0;
    hi_gpio_groupbit_info stIntInfo;
    hi_gpio_groupbit_info stRstInfo;

    stIntInfo.group_num = INT_GPIO_CHIP;
    stIntInfo.bit_num = INT_GPIO_OFFSET;
    stIntInfo.value = 0;

    stRstInfo.group_num = RST_GPIO_CHIP;
    stRstInfo.bit_num = RST_GPIO_OFFSET;
    stRstInfo.value = 1;

    ret = i2cdev_init();
    if (ret)
    {
        dev_err(NULL, " i2cdev_init fail!\n");
        goto error_end;
    }

    hi_gpio_set_dir(&stIntInfo);
    hi_gpio_set_dir(&stRstInfo);

    ret = ft_reset(&stRstInfo);
    if (ret)
    {
        dev_err(NULL, " ft_reset fail!\n");
        goto error_end;
    }
    ret = devinput_init();
    if (ret)
    {
        dev_err(NULL, " devinput_init fail!\n");
        goto error_end;
    }

    return 0;
error_end:
    return -1;
}

INT_GPIO_CHIP和INT_GPIO_OFFSET都是在宏定義
#elif (defined(BOARD_DEMB) && (defined(HI3556AV100) || defined(HI3519AV100)))下定義的

#define RST_GPIO_CHIP (2)
#define RST_GPIO_OFFSET (6)
#define INT_GPIO_CHIP (2)
#define INT_GPIO_OFFSET (5)

這些管腳可以在這里《Hi3556AV100 Demo 單板使用指南.pdf》中看到，分別得出觸摸屏的中斷和復位管腳

1.1 對觸摸屏進行復位

static int ft_reset(hi_gpio_groupbit_info* pstRstInfo)
{
    pstRstInfo->value = 1;
    hi_gpio_write_bit(pstRstInfo);
    pstRstInfo->value = 0;
    hi_gpio_write_bit(pstRstInfo);
    msleep(5);
    pstRstInfo->value = 1;
    hi_gpio_write_bit(pstRstInfo);
    return 0;
}

對觸摸屏進行復位；

1.2 input系統初始化

static int devinput_init(void)
{
    int error = 0;
    /* 1. distribution a "input_dev" structure */
    ft_ts_dev = input_allocate_device();
    if (ft_ts_dev == NULL)
    {
        printk(" func:%s line:%d \r\n", __FUNCTION__, __LINE__);
        return -1;
    }
    ft_ts_dev->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    set_bit(EV_SYN, ft_ts_dev->evbit);
    set_bit(EV_KEY, ft_ts_dev->evbit);
    set_bit(EV_ABS, ft_ts_dev->evbit);
    set_bit(INPUT_PROP_DIRECT, ft_ts_dev->propbit);
    input_set_abs_params(ft_ts_dev, ABS_MT_POSITION_X, 0 , FT_SCREEN_WIDTH_NUM, 0, 0);
    input_set_abs_params(ft_ts_dev, ABS_MT_POSITION_Y, 0, FT_SCREEN_HEIGHT_NUM, 0, 0);
    input_set_abs_params(ft_ts_dev, ABS_MT_TOUCH_MAJOR,
                         0, 0xff, 0, 0);
    input_set_abs_params(ft_ts_dev, ABS_MT_PRESSURE,
                         0, 0xff, 0, 0);
    input_set_abs_params(ft_ts_dev, ABS_MT_TRACKING_ID,
                         0, 0xff, 0, 0);

    error = input_mt_init_slots(ft_ts_dev, FT_MAX_TOUCH_POINTS,
                                INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);

    if (error)
    { return error; }
    ft_ts_dev->name = "ft";
    ft_ts_dev->id.bustype = BUS_I2C;

    error = input_register_device(ft_ts_dev);
    if (error)
    {
        dev_err(NULL, "failed to register input device: %d\n", error);
        return error;
    }

    /**request_threaded_irq(unsigned int irq,irq_handler_t handler,irq_handler_t thread_fn,unsigned long irqflags,const char * devname,void * dev_id)*/
    error = fts_irq_register();
    if(error)
    {
        dev_err(NULL, "failed to register input device: %d\n", error);
        return error;
    }
    /**Clear INT*/
    touch_set_reg(0x045f241C, 0x20);
    return 0;
}

1. set_bit()告訴input輸入子系統支持哪些按鍵

evbit：

事件類型（包括EV_RST,EV_REL,EV_MSC,EV_KEY,EV_ABS,EV_REP等）

propbit：

set_bit(INPUT_PROP_DIRECT,dev->propbit);//表明設備的坐標直接和屏幕坐標向對應

2. input_set_abs_params

給設備的input_dev結構體初始化，這些input_dev如果想被當成多點屏處理的話，只需要給input_dev額外增加以下幾個參數：

input_set_abs_params(ft_ts_dev, ABS_MT_POSITION_X, 0 , FT_SCREEN_WIDTH_NUM, 0, 0);
input_set_abs_params(ft_ts_dev, ABS_MT_POSITION_Y, 0, FT_SCREEN_HEIGHT_NUM, 0, 0);
input_set_abs_params(ft_ts_dev, ABS_MT_TOUCH_MAJOR,
                     0, 0xff, 0, 0);
 //相當於單點屏的ABX_PRESSURE
input_set_abs_params(ft_ts_dev, ABS_MT_PRESSURE,
                     0, 0xff, 0, 0);
input_set_abs_params(ft_ts_dev, ABS_MT_TRACKING_ID,
                     0, 0xff, 0, 0);
//確定第幾手指來上報的數據

input_set_abs_params(idev, ABS_X, -64, 64, 4, 0);

對於X軸范圍是-64到+64，數據誤差是-4到+4，中心平滑位置是0

3. input_mt_init_slots

報告最大支持的點數

4. input_register_device

注冊input子系統

5. 通過注冊中斷管腳

fts_irq_register注冊中斷

2. 中斷函數處理

static irqreturn_t ftint_irq(int irq, void *data)
{
    int i;
    bool act;
    struct input_dev* input = ft_ts_dev;
    ts_event event;
    int ret = touch_event_handler(&event);
    if(ret)
        printk( "\n buffer_read failed \n");
    if(event.point_num != 0)
    {
        for(i = 0; i < event.touch_point; i++)
        {
            input_mt_slot(input, i);
            act = (event.au8_touch_event[i] == FT_EVENT_PRESS_DOWN || event.au8_touch_event[i] == FT_EVENT_CONTACT);
            input_mt_report_slot_state(input, MT_TOOL_FINGER, act);
            if (!act)
                continue;
            input_report_abs(input, ABS_MT_POSITION_X, event.au16_x[i]);
            input_report_abs(input, ABS_MT_POSITION_Y, event.au16_y[i]);
        }
    }
    input_mt_sync_frame(input);
    input_sync(input);
    return IRQ_HANDLED;
}

1. touch_event_handler函數

ret = hi_i2c_read(0x0, buf, FT_MAX_BUFUSED_NUM);

在這里，使用了hi_i2c_read，在文件i2cdev.c中，注意i2c_board_info的一般是8位從地址；

一般來說，觸摸屏有固件的，然后每一個固件都代表類似的協議，由於我們沒有相應的協議，所以按照下面的來看：

for (i = 0; i < FT_MAX_TOUCH_POINTS; i++)
    {
        event->touch_point++;

        /**Notice the  array bound !!*/
        /* 獲取x坐標 */
        event->au16_x[i] =
            (s16) (buf[FT_TOUCH_X_H_POS + 6 * i] & 0x0F) << 8 | (s16) buf[FT_TOUCH_X_L_POS + 6 * i];
        /* 獲取y坐標 */
        event->au16_y[i] =
            (s16) (buf[FT_TOUCH_Y_H_POS + 6 * i] & 0x0F) << 8 | (s16) buf[FT_TOUCH_Y_L_POS + 6 * i];
        /* 按下，松開，觸摸 */
        event->au8_touch_event[i] =
            buf[FT_TOUCH_EVENT_POS + 6 * i] >> 6;
        event->au8_finger_id[i] =
            (buf[FT_TOUCH_FINGER_POS + 6 * i]) >> 4;

        /**pressure and area not used !!*/
#if 0
        event->area[i] =
            (buf[FT_TOUCH_AREA_POS + 6 * i]) >> 4;
        event->pressure[i] =
            (s16) buf[FTS_TOUCH_PRE_POS + 6 * i];

        if (0 == event->area[i])
            event->area[i] = 0x09;

        if (0 == event->pressure[i])
            event->pressure[i] = 0x3f;
#endif
        if ((event->au8_touch_event[i]==0 || event->au8_touch_event[i]==2)&&(event->point_num==0))
        {
            printk("abnormal touch data from fw");
            return -1;
        }
    }

2. 中斷函數：

static irqreturn_t ftint_irq(int irq, void *data)
{
    int i;
    bool act;
    struct input_dev* input = ft_ts_dev;
    ts_event event;
    int ret = touch_event_handler(&event);
    if(ret)
        printk( "\n buffer_read failed \n");
    if(event.point_num != 0)
    {
        for(i = 0; i < event.touch_point; i++)
        {
            input_mt_slot(input, i);
            act = (event.au8_touch_event[i] == FT_EVENT_PRESS_DOWN || event.au8_touch_event[i] == FT_EVENT_CONTACT);
            input_mt_report_slot_state(input, MT_TOOL_FINGER, act);
            if (!act)
                continue;
            input_report_abs(input, ABS_MT_POSITION_X, event.au16_x[i]);
            input_report_abs(input, ABS_MT_POSITION_Y, event.au16_y[i]);
        }
    }
    input_mt_sync_frame(input);
    input_sync(input);
    return IRQ_HANDLED;
}