触摸屏驱动s3c2410_ts.c分析

Linux设备驱动工程师之路——触摸屏驱动s3c2410_ts.c分析

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转载请自 http://blog.csdn.net/ayangke 

一、触摸屏硬件知识

 

1.模块原理图

S3C2440有8路的ADC通道其中触摸屏控制器接口XP,XM,YP,YM与四路ADC通道复用四个IO引脚。从原理图看出8路ADC只有一个A/D转换器，通过一个8选1开关MUX来选通哪一路A/D通道进行转换。触摸屏控制会产生两个中断，一个触摸屏中断INT_ADC,一个ADC_转换完成中断INT_ADC。ADC需要时钟才能工作，因为它需要设置采样率。

再复习一下ARM裸机实验时触摸屏寄存器操作流程

流程：

         初始化

         1设置采样延时和分频值ADCDLY ADCCON

         2中断相关设置

         3设置触摸屏AD转换为等待中断模式 ADCTSC

         中断服务函数

         4清相关挂起寄存器

         5设置转换模式，一般为连续x,y转换

6 启动转换

          7 转换完成后读取x y坐标ADCDAT0ADCDAT1

          8 设置触摸屏AD转换为等待中断模式，设置等待弹起中断ADCTSC

9 弹起中断发生后，设置触摸屏转换为等待中断模式，等待下一次触笔按下rADCTSC

         程序

二、触摸屏驱动程序

 

1.模块初始化

static int __init s3c2410ts_init(void)
{
    struct input_dev *input_dev;

    //获取时钟
    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);
    //使能时钟
    //需要时钟的是因为触摸屏要用到ADC转换，而完成ADC转换则需要时钟（采用时间）

    //映射ADC的IO内存
    base_addr=ioremap(S3C2410_PA_ADC,0x20);
    if (base_addr == NULL) {
        printk(KERN_ERR "Failed to remap register block\n");
        return -ENOMEM;
    }

    //初始化触摸屏的IO引脚
    /* Configure GPIOs */
    s3c2410_ts_connect();

    //设置预分频值
    iowrite32(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(0xFF),\
             base_addr+S3C2410_ADCCON);
    iowrite32(0xffff,  base_addr+S3C2410_ADCDLY);//设置采用延时
    iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
//设置触摸屏控制器为等待按下中断

    /* Initialise input stuff */
    //申请一个input设备
    input_dev = input_allocate_device();

    if (!input_dev) {
        printk(KERN_ERR "Unable to allocate the input device !!\n");
        return -ENOMEM;
    }

    dev = input_dev;

    //设置可被支持的事件为同步、按键、绝对坐标事件
dev->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
//设置按键时间类型为触摸屏
    dev->keybit[BITS_TO_LONGS(BTN_TOUCH)] = BIT(BTN_TOUCH);

    //设置事件数值范围X,Y坐标范围为0到3FF,按键数值范围从0，到1
    input_set_abs_params(dev, ABS_X, 0, 0x3FF, 0, 0);
    input_set_abs_params(dev, ABS_Y, 0, 0x3FF, 0, 0);
    input_set_abs_params(dev, ABS_PRESSURE, 0, 1, 0, 0);

    //设置设备的身份信息
    dev->name = s3c2410ts_name;
    dev->id.bustype = BUS_RS232;
    dev->id.vendor = 0xDEAD;
    dev->id.product = 0xBEEF;
    dev->id.version = S3C2410TSVERSION;


    /* Get irqs */
    //获取触摸屏中断IRQ_TC,ADC转换完成中断IRQ_ADC
    if (request_irq(IRQ_ADC, stylus_action, IRQF_SHARED|IRQF_SAMPLE_RANDOM,
        "s3c2410_action", dev)) {
        printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_ADC !\n");
        iounmap(base_addr);
        return -EIO;
    }
    if (request_irq(IRQ_TC, stylus_updown, IRQF_SAMPLE_RANDOM,
            "s3c2410_action", dev)) {
        printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_TC !\n");
        iounmap(base_addr);
        return -EIO;
    }

    printk(KERN_INFO "%s successfully loaded\n", s3c2410ts_name);

    /* All went ok, so register to the input system */
    //注册设备
    input_register_device(dev);

    return 0;
}

static int __init s3c2410ts_init(void)
{
	struct input_dev *input_dev;

	//获取时钟
	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);
	//使能时钟
	//需要时钟的是因为触摸屏要用到ADC转换，而完成ADC转换则需要时钟（采用时间）

	//映射ADC的IO内存
	base_addr=ioremap(S3C2410_PA_ADC,0x20);
	if (base_addr == NULL) {
		printk(KERN_ERR "Failed to remap register block\n");
		return -ENOMEM;
	}

	//初始化触摸屏的IO引脚
	/* Configure GPIOs */
	s3c2410_ts_connect();

	//设置预分频值
	iowrite32(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(0xFF),\
		     base_addr+S3C2410_ADCCON);
	iowrite32(0xffff,  base_addr+S3C2410_ADCDLY);//设置采用延时
	iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
//设置触摸屏控制器为等待按下中断

	/* Initialise input stuff */
	//申请一个input设备
	input_dev = input_allocate_device();

	if (!input_dev) {
		printk(KERN_ERR "Unable to allocate the input device !!\n");
		return -ENOMEM;
	}

	dev = input_dev;
	
	//设置可被支持的事件为同步、按键、绝对坐标事件
dev->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
//设置按键时间类型为触摸屏
	dev->keybit[BITS_TO_LONGS(BTN_TOUCH)] = BIT(BTN_TOUCH);

	//设置事件数值范围X,Y坐标范围为0到3FF,按键数值范围从0，到1
	input_set_abs_params(dev, ABS_X, 0, 0x3FF, 0, 0);
	input_set_abs_params(dev, ABS_Y, 0, 0x3FF, 0, 0);
	input_set_abs_params(dev, ABS_PRESSURE, 0, 1, 0, 0);

	//设置设备的身份信息
	dev->name = s3c2410ts_name;
	dev->id.bustype = BUS_RS232;
	dev->id.vendor = 0xDEAD;
	dev->id.product = 0xBEEF;
	dev->id.version = S3C2410TSVERSION;


	/* Get irqs */
	//获取触摸屏中断IRQ_TC,ADC转换完成中断IRQ_ADC
	if (request_irq(IRQ_ADC, stylus_action, IRQF_SHARED|IRQF_SAMPLE_RANDOM,
		"s3c2410_action", dev)) {
		printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_ADC !\n");
		iounmap(base_addr);
		return -EIO;
	}
	if (request_irq(IRQ_TC, stylus_updown, IRQF_SAMPLE_RANDOM,
			"s3c2410_action", dev)) {
		printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_TC !\n");
		iounmap(base_addr);
		return -EIO;
	}

	printk(KERN_INFO "%s successfully loaded\n", s3c2410ts_name);

	/* All went ok, so register to the input system */
	//注册设备
	input_register_device(dev);

	return 0;
}

我们再来看看模块初始化函数中初始化触摸屏的IO引脚的s3c2410_ts_connect();函数

static inline void s3c2410_ts_connect(void)
{
    s3c2410_gpio_cfgpin(S3C2410_GPG12, S3C2410_GPG12_XMON);
    s3c2410_gpio_cfgpin(S3C2410_GPG13, S3C2410_GPG13_nXPON);
    s3c2410_gpio_cfgpin(S3C2410_GPG14, S3C2410_GPG14_YMON);
    s3c2410_gpio_cfgpin(S3C2410_GPG15, S3C2410_GPG15_nYPON);
}

static inline void s3c2410_ts_connect(void)
{
	s3c2410_gpio_cfgpin(S3C2410_GPG12, S3C2410_GPG12_XMON);
	s3c2410_gpio_cfgpin(S3C2410_GPG13, S3C2410_GPG13_nXPON);
	s3c2410_gpio_cfgpin(S3C2410_GPG14, S3C2410_GPG14_YMON);
	s3c2410_gpio_cfgpin(S3C2410_GPG15, S3C2410_GPG15_nYPON);
}

触摸屏控制器接口是与IO端口复用的。

 

2.触摸屏中断服务函数

static irqreturn_t stylus_updown(int irq, void *dev_id)
{
    unsigned long data0;
    unsigned long data1;
    int updown;

    if (down_trylock(&ADC_LOCK) == 0) {
        OwnADC = 1;

        //读取ADCDAT0和ADCDAT1寄存器，判断是按下中断还是弹起中断
        //ADCDAT0和ADCDAT1查手册可知其第15位当按下时为0，弹起为1
        data0 = ioread32(base_addr+S3C2410_ADCDAT0);
        data1 = ioread32(base_addr+S3C2410_ADCDAT1);

        updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));

        if (updown) {
            touch_timer_fire(0);//当判断为按下时
        } else {
            OwnADC = 0;
            up(&ADC_LOCK);
        }
    }

    return IRQ_HANDLED;
}

static irqreturn_t stylus_updown(int irq, void *dev_id)
{
	unsigned long data0;
	unsigned long data1;
	int updown;

	if (down_trylock(&ADC_LOCK) == 0) {
		OwnADC = 1;

		//读取ADCDAT0和ADCDAT1寄存器，判断是按下中断还是弹起中断
		//ADCDAT0和ADCDAT1查手册可知其第15位当按下时为0，弹起为1
		data0 = ioread32(base_addr+S3C2410_ADCDAT0);
		data1 = ioread32(base_addr+S3C2410_ADCDAT1);

		updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));

		if (updown) {
			touch_timer_fire(0);//当判断为按下时
		} else {
			OwnADC = 0;
			up(&ADC_LOCK);
		}
	}

	return IRQ_HANDLED;
}

我们再来看touch_timer_fire(0);这个函数

static void touch_timer_fire(unsigned long data)
{
    unsigned long data0;
    unsigned long data1;
    int updown;

//读取ADCDAT0和ADCDAT1判断为弹起还是按下
    data0 = ioread32(base_addr+S3C2410_ADCDAT0);
    data1 = ioread32(base_addr+S3C2410_ADCDAT1);

    updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));

    //当按下时
    if (updown) {
        if (count != 0) {
            //当两次转换完成后
            long tmp;

            tmp = xp;
            xp = yp;
            yp = tmp;

                        xp >>= 2;
                        yp >>= 2;
            //求取两次转换坐标的平均值，然后报告

            input_report_abs(dev, ABS_X, xp);
            input_report_abs(dev, ABS_Y, yp);

            input_report_key(dev, BTN_TOUCH, 1);
            input_report_abs(dev, ABS_PRESSURE, 1);
            input_sync(dev);
        }

        xp = 0;
        yp = 0;
        count = 0;

        //启动ADC转换
        //设置ADCTSC，转换模式
        iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);
        //设置ADCCON，启动转换
        iowrite32(ioread32(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
    } else {
        //如果是弹起了将count清0，并报告弹起事件
                count = 0;

        input_report_key(dev, BTN_TOUCH, 0);
        input_report_abs(dev, ABS_PRESSURE, 0);
        input_sync(dev);

        //再次设置触摸屏为等待中断模式
        iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
        if (OwnADC) {
            OwnADC = 0;
            up(&ADC_LOCK);
        }
    }

static void touch_timer_fire(unsigned long data)
{
  	unsigned long data0;
  	unsigned long data1;
	int updown;

//读取ADCDAT0和ADCDAT1判断为弹起还是按下
  	data0 = ioread32(base_addr+S3C2410_ADCDAT0);
  	data1 = ioread32(base_addr+S3C2410_ADCDAT1);

 	updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));

	//当按下时
 	if (updown) {
 		if (count != 0) {
			//当两次转换完成后
			long tmp;
                                                                                                 
			tmp = xp;
			xp = yp;
			yp = tmp;
                                                                                                 
                        xp >>= 2;
                        yp >>= 2;
			//求取两次转换坐标的平均值，然后报告

 			input_report_abs(dev, ABS_X, xp);
 			input_report_abs(dev, ABS_Y, yp);

 			input_report_key(dev, BTN_TOUCH, 1);
 			input_report_abs(dev, ABS_PRESSURE, 1);
 			input_sync(dev);
 		}

 		xp = 0;
 		yp = 0;
 		count = 0;

		//启动ADC转换
		//设置ADCTSC，转换模式
 		iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);
		//设置ADCCON，启动转换
 		iowrite32(ioread32(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
 	} else {
		//如果是弹起了将count清0，并报告弹起事件
				count = 0;

		input_report_key(dev, BTN_TOUCH, 0);
 		input_report_abs(dev, ABS_PRESSURE, 0);
 		input_sync(dev);

		//再次设置触摸屏为等待中断模式
 		iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
		if (OwnADC) {
			OwnADC = 0;
			up(&ADC_LOCK);
		}
 	}

3.ADC中断

static irqreturn_t stylus_action(int irq, void *dev_id)
{
    unsigned long data0;
    unsigned long data1;

    if (OwnADC) {
        data0 = ioread32(base_addr+S3C2410_ADCDAT0);
        data1 = ioread32(base_addr+S3C2410_ADCDAT1);

        //读取转换后X,Y值
        xp += data0 & S3C2410_ADCDAT0_XPDATA_MASK;
        yp += data1 & S3C2410_ADCDAT1_YPDATA_MASK;
        count++;

        //通过对count的判断进行两次转换，两次转换后求和的值将在触摸屏中断里面报告时间的时候除以2求得平均值然后上报。
        if (count < (1<<2)) {
            iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);
            iowrite32(ioread32(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
        } else {
        //当两次转换完成时
            mod_timer(&touch_timer, jiffies+1);//设置定时器的定时值为一个时钟滴答，一个滴答之后touch_timer_fire函数被调用用来报告时间数值
        /*该定时器的初始化如下
        static struct timer_list touch_timer =
        TIMER_INITIALIZER(touch_timer_fire, 0, 0);
        */
            iowrite32(WAIT4INT(1), base_addr+S3C2410_ADCTSC);//重新设置触摸屏为等待中断模式
        }
    }

    return IRQ_HANDLED;
}