触摸屏

触摸屏

首先置位相应时钟

adc_clock = clk_get(NULL, "adc");
    if (!adc_clock) {
        printk(KERN_ERR "failed to get adc clock source\n");
        return -ENOENT;
    }
    clk_enable(adc_clock);

触摸屏接口模式：

1、Normal Conversion Mode
2、Separate X/Y position conversion Mode
3、Auto(Sequential) X/Y position conversion Mode
4、Waiting for Interrupt Mode
5、Standby Mode

//触摸屏寄存器
struct s3c_ts_regs {
    unsigned long adccon;
    unsigned long adctsc;
    unsigned long adcdly;
    unsigned long adcdat0;
    unsigned long adcdat1;
    unsigned long adcupdn;
};

static volatile struct s3c_ts_regs *s3c_ts_regs;

模式设置：


等待中断等效图

等待松开，等待按下模式

static void enter_wait_pen_down_mode(void)
{
    s3c_ts_regs->adctsc = 0xd3;
}

static void enter_wait_pen_up_mode(void)
{
    s3c_ts_regs->adctsc = 0x1d3;
}

x/y转化模式：

!Alt text

static void enter_measure_xy_mode(void)
{
    s3c_ts_regs->adctsc = (1<<3)|(1<<2);
}

启动ADC控制器

static void start_adc(void)
{
    s3c_ts_regs->adccon |= (1<<0);
}

中断函数

static irqreturn_t pen_down_up_irq(int irq, void *dev_id)
{
    if (s3c_ts_regs->adcdat0 & (1<<15))
    {
        printk("pen up\n");
        enter_wait_pen_down_mode();
    }
    else
    {
        //printk("pen down\n");
        //enter_wait_pen_up_mode();
        enter_measure_xy_mode();
        start_adc();
    }
    return IRQ_HANDLED;
}

措施4:软件过滤

static int s3c_filter_ts(int x[], int y[])
{
#define ERR_LIMIT 10

    int avr_x, avr_y;
    int det_x, det_y;

    avr_x = (x[0] + x[1])/2;
    avr_y = (y[0] + y[1])/2;

    det_x = (x[2] > avr_x) ? (x[2] - avr_x) : (avr_x - x[2]);
    det_y = (y[2] > avr_y) ? (y[2] - avr_y) : (avr_y - y[2]);

    if ((det_x > ERR_LIMIT) || (det_y > ERR_LIMIT))
        return 0;

    avr_x = (x[1] + x[2])/2;
    avr_y = (y[1] + y[2])/2;

    det_x = (x[3] > avr_x) ? (x[3] - avr_x) : (avr_x - x[3]);
    det_y = (y[3] > avr_y) ? (y[3] - avr_y) : (avr_y - y[3]);

    if ((det_x > ERR_LIMIT) || (det_y > ERR_LIMIT))
        return 0;

    return 1;
}

定时器函数

static void s3c_ts_timer_function(unsigned long data)
{
    if (s3c_ts_regs->adcdat0 & (1<<15))
    {
        /* 已经松开 */
        enter_wait_pen_down_mode();
    }
    else
    {
        /* 测量X/Y坐标 */
        enter_measure_xy_mode();
        start_adc();
    }
}

adc中断：

static irqreturn_t adc_irq(int irq, void *dev_id)
{
    static int cnt = 0;
    static int x[4], y[4];
    int adcdat0, adcdat1;

    /* 优化措施2: 如果ADC完成时, 发现触摸笔已经松开, 则丢弃此次结果 */
    adcdat0 = s3c_ts_regs->adcdat0;
    adcdat1 = s3c_ts_regs->adcdat1;

if (s3c_ts_regs->adcdat0 & (1<<15))
    {
        /* 已经松开 */
        cnt = 0;
        enter_wait_pen_down_mode();
    }
    else
    {
        // printk("adc_irq cnt = %d, x = %d, y = %d\n", ++cnt, adcdat0 & 0x3ff, adcdat1 & 0x3ff);
        /* 优化措施3: 多次测量求平均值 */
        x[cnt] = adcdat0 & 0x3ff;
        y[cnt] = adcdat1 & 0x3ff;
        ++cnt;
        if (cnt == 4)
        {
            /* 优化措施4: 软件过滤 */
            if (s3c_filter_ts(x, y))
            {           
                printk("x = %d, y = %d\n", (x[0]+x[1]+x[2]+x[3])/4, (y[0]+y[1]+y[2]+y[3])/4);
            }
            cnt = 0;
            enter_wait_pen_up_mode();


            /* 启动定时器处理长按/滑动的情况 */
            mod_timer(&ts_timer, jiffies + HZ/100);
        }
        else
        {
            enter_measure_xy_mode();
            start_adc();
        }       
    }
    return IRQ_HANDLED;
}

初始化

static int s3c_ts_init(void)
{
//1、分配一个input_dev结构体
s3c_ts_dev = input_allocate_device();

//2、设置
//2.1 能产生哪类事件
set_bit(EV_KEY,s3c_ts_dev->evbit);
set_bit(EV_ABS,s3c_ts_dev->evbit);
//2.2 能产生这类事件的哪些事件
set_bit(BTN_TOUCH, s3c_ts_dev->keybit);
input_set_abs_params(s3c_ts_dev, ABS_X, 0, 0x3FF, 0, 0);
input_set_abs_params(s3c_ts_dev, ABS_Y, 0, 0x3FF, 0, 0);
input_set_abs_params(s3c_ts_dev, ABS_PRESSURE, 0, 1, 0, 0);

//3、注册
input_register_device(s3c_ts_dev);

//4、硬件相关的操作
/* 4.1 使能时钟(CLKCON[15]) */
adc_clock = clk_get(NULL, "adc");
if (!adc_clock) {
    printk(KERN_ERR "failed to get adc clock source\n");
    return -ENOENT;
}
clk_enable(adc_clock);

/* 4.2 设置S3C2440的ADC/TS寄存器 */
s3c_ts_regs = ioremap(0x58000000, sizeof(struct s3c_ts_regs));

/* bit[14]  : 1-A/D converter prescaler enable
* bit[13:6]: A/D converter prescaler value,
*          49,ADCCLK=PCLK/(49+1)=50MHz/(49+1)=1MHz
* bit[0]: A/D conversion starts by enable. 先设为0
*/
s3c_ts_regs->adccon = (1<<14)|(49<<6);

request_irq(IRQ_TC, pen_down_up_irq, IRQF_SAMPLE_RANDOM, "ts_pen", NULL);
request_irq(IRQ_ADC, adc_irq, IRQF_SAMPLE_RANDOM, "adc", NULL);

//优化错施1: 
//设置ADCDLY为最大值, 这使得电压稳定后再发出IRQ_TC中断
s3c_ts_regs->adcdly = 0xffff;

//优化措施5: 使用定时器处理长按,滑动的情况
init_timer(&ts_timer);
ts_timer.function = s3c_ts_timer_function;
add_timer(&ts_timer);

//等待按下
enter_wait_pen_down_mode();

return 0;

}

硬件相关操作时
有数据产生时，input_even
从input_device链表中找到,,调用input_handle.handler中的event函数。

比对过程：

根据input_handler中的id_table与input_dev中的id.bustype

看下evdev_handler
input_event(input,type,button->code,!!state);
上报完事件还要上报个同步事件。
input_sync(input);

input_sync()

static inline void input_sync(struct input_dev *dev)
{
    input_event(dev,EV_SYN,SYN_REPORT,0);
    //表示这个事件已经上报完毕
}

static struct input_handler evdev_handler = {
    .event      = evdev_event,
    .connect    = evdev_connect,
    .disconnect = evdev_disconnect,
    .fops       = &evdev_fops,
    .minor      = EVDEV_MINOR_BASE,
    .name       = "evdev",
    .id_table   = evdev_ids,
};

看下 evdev_ids

static const struct input_device_id evdev_ids[] = {
    { .driver_info = 1 },   /* Matches all devices */
    { },            /* Terminating zero entry */
};