S3C6410触摸屏驱动分析

一. device的注册
1.0 两个注册
//在smdk6410_machine_init中既注册了touchscreen的私有信息也注册了ts资源

在arch/arm/mach-s3c64xx/mach-smdk6410.c中
static void __init smdk6410_machine_init(void)
{
    //在arch/arm/mach-s3c64xx/dev-ts.c中
    s3c_ts_set_platdata(&s3c_ts_platform);                                  //1.设备私有信息的注册
    //在driver/base/platform.c中
    platform_add_devices(smdk6410_devices, ARRAY_SIZE(smdk6410_devices));   //2.设备资源的注册
}

1.1 ts私有信息的注册
在arch/arm/mach-s3c64xx/mach-smdk6410.c中

static struct s3c_ts_mach_info s3c_ts_platform __initdata = {
    .delay               = 10000,                    //延时
    .presc               = 49,                       //分频
    .oversampling_shift  = 2,                        //分频
    .resol_bit           = 12,                       //精度     
    .s3c_adc_con         = ADC_TYPE_2,               //分频     
};
smdk6410_machine_init
{
    //下面这个函数在arch/arm/mach-s3c64xx/dev-ts.c中
    s3c_ts_set_platdata(&s3c_ts_platform);
}

1.2 ts设备资源的注册

//在arch/arm/mach-s3c64xx/dev-ts.c中
static struct resource s3c_ts_resource[] = {
    [0] = {
        .start = SAMSUNG_PA_ADC,                        //0x7E00B000
        .end = SAMSUNG_PA_ADC + SZ_256 - 1,             //0x7E00B100    
        .flags = IORESOURCE_MEM,
    },
    [1] = {
        .start = IRQ_PENDN,                             //0x5e=94
        .end = IRQ_PENDN,
        .flags = IORESOURCE_IRQ,
    },
    [2] = {
        .start = IRQ_ADC,                                //0x5f=95
        .end = IRQ_ADC,
        .flags = IORESOURCE_IRQ,
    }
};
struct platform_device s3c_device_ts = {
    .name         = "s3c-ts",
    .id         = -1,
    .num_resources     = ARRAY_SIZE(s3c_ts_resource),
    .resource     = s3c_ts_resource,
};
//在arch/arm/mach-s3c64xx/mach-smdk6410.c中
static struct platform_device *smdk6410_devices[] __initdata = {
    &s3c_device_ts,                //把ts放入到总的ts列表中
}
//在arch/arm/mach-s3c64xx/mach-smdk6410.c中
static void __init smdk6410_machine_init(void)
{
    //在driver/base/platform.c中一起注册
    platform_add_devices(smdk6410_devices, ARRAY_SIZE(smdk6410_devices));
}

---

二. device_driver
2.0 两个宏

#define WAIT4INT(x)              //只是针对于S3C_ADCTSC寄存器
        (((x)<<8) |              //<bit8> 0->down 1->up interrupt signal
        S3C_ADCTSC_YM_SEN |      //<bit7> 1 = Switch enable (YM = VSSA_ADC)
        S3C_ADCTSC_YP_SEN |      //<bit6> 1 = Switch disable (YP=AIN5, Hi-z) 
        //XM_SEN                //<bit5> 0 = Switch disable (XM = AIN6, Hi-z)
        S3C_ADCTSC_XP_SEN |      //<bit4> 1 = Switch disable (XP=AIN7, Hi-z)
        //PULL_UP               //<bit3> 0 = XP Pull-up Enable.
        //AUTO_PST              //<bit2> 0 = Normal ADC conversion.         
        S3C_ADCTSC_XY_PST(3))    //<bit1-0> 3: Waiting for Interrupt Mode 
#define AUTOPST     
    (S3C_ADCTSC_YM_SEN |        //1 = Switch enable (YM = VSSA_ADC)
    S3C_ADCTSC_YP_SEN |         //1 = Switch disable (YP=AIN5, Hi-z) 
    S3C_ADCTSC_XP_SEN |         //1 = Switch disable (XP=AIN7, Hi-z) 
    S3C_ADCTSC_AUTO_PST |       //1 = Auto Sequential measurement of X-position, Y-position
    S3C_ADCTSC_XY_PST(0))       //0 = No operation mode
WAIT4INT(x) :
            当x=0时,设为等侍down中断
             当x=1时,设为等侍up中断

2.1 初始化
ok6410的touchscreen在内核源码的位置:driver/input/touchscreen/s3c-ts.c
device 与 device_driver按名字s3c-ts匹配之后,就进入s3c_ts_probe函数

static struct platform_driver s3c_ts_driver = {
    .probe = s3c_ts_probe,
    .remove = s3c_ts_remove,
    .suspend = s3c_ts_suspend,
    .resume = s3c_ts_resume,
    .driver        = {
        .owner    = THIS_MODULE,
        .name    = "s3c-ts",
    },
};
static int __init s3c_ts_init(void)
{
    return platform_driver_register(&s3c_ts_driver);
}
static void __exit s3c_ts_exit(void)
{
    platform_driver_unregister(&s3c_ts_driver);
}
module_init(s3c_ts_init);
module_exit(s3c_ts_exit);

2.2 probe函数

static int __init s3c_ts_probe(struct platform_device *pdev)
{
    struct resource *res;
    struct device *dev;
    struct input_dev *input_dev;
    struct s3c_ts_mach_info * s3c_ts_cfg;
    int ret, size;
    dev = &pdev->dev;
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);                //获取ts寄存器地址
    size = (res->end - res->start) + 1;
    ts_mem = request_mem_region(res->start, size, pdev->name);           //申请I/O内存
    ts_base = ioremap(res->start, size);                                 //request_mem_region申请的内存在使用前要调用ioremap
    ts_clock = clk_get(&pdev->dev, "adc");                               //获取clock    
    clk_enable(ts_clock);                                                //在初始化时disable了ts_clock,这个地方要enable
    
                                                                //下面这几行是要把ts的配置信息写到寄存器中去
    s3c_ts_cfg = s3c_ts_get_platdata(&pdev->dev);                        //获取ts的配置信息,
                                                                         //ts的私有信息:在arch/arm/mach-s3c64xx/mach-smdk6410.c中
    //enable prescaler &&　设置prescaler_value=s3c_ts_cfg->presc
    writel(S3C_ADCCON_PRSCEN | S3C_ADCCON_PRSCVL(s3c_ts_cfg->presc&0xff), ts_base+S3C_ADCCON);
   
   //s3c_ts_cfg->delay=0x10000 --> External input clock 
    writel(s3c_ts_cfg->delay & 0xffff, ts_base+S3C_ADCDLY);
    
    //A/D converter resolution selection--> 12-bit A/D conversion
    writel(readl(ts_base+S3C_ADCCON)|S3C_ADCCON_RESSEL_12BIT, ts_base+S3C_ADCCON);
    //设为等侍down中断模式
    writel(WAIT4INT(0), ts_base+S3C_ADCTSC);
    ts = kzalloc(sizeof(struct s3c_ts_info), GFP_KERNEL);           //下面这几行是要初始化s3c_ts_info结构体
    input_dev = input_allocate_device();
   
    ts->dev = input_dev;
    ts->dev->evbit[0] = ts->dev->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    ts->dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
    if (s3c_ts_cfg->resol_bit==12) {
        input_set_abs_params(ts->dev, ABS_X, 0, 0xFFF, 0, 0);                //设置x轴的最大最小值
        input_set_abs_params(ts->dev, ABS_Y, 0, 0xFFF, 0, 0);                //设置y轴的最大最小值
    } 
    input_set_abs_params(ts->dev, ABS_PRESSURE, 0, 1, 0, 0);                 //设置Press状态的最大最小值(按下或空闲)   
    sprintf(ts->phys, "input(ts)");
    ts->dev->name = s3c_ts_name;
    ts->dev->phys = ts->phys;
    ts->dev->id.bustype = BUS_RS232;
    ts->dev->id.vendor = 0xDEAD;
    ts->dev->id.product = 0xBEEF;
    ts->dev->id.version = S3C_TSVERSION;
    ts->shift = s3c_ts_cfg->oversampling_shift;
    ts->resol_bit = s3c_ts_cfg->resol_bit;
    ts->s3c_adc_con = s3c_ts_cfg->s3c_adc_con;
    /* For IRQ_PENDUP */
    ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);                //获取中断号
    //申请中断,RANDOM表示设备可以看作随机的发生源
    ret = request_irq(ts_irq->start, stylus_updown, IRQF_SAMPLE_RANDOM, "s3c_updown", ts); //申请中断
   
    /* For IRQ_ADC */
    ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 1);               //获取中断号
    ret = request_irq(ts_irq->start, stylus_action, IRQF_SAMPLE_RANDOM | IRQF_SHARED, "s3c_action", ts); //申请共享中断
    
    /* All went ok, so register to the input system */
    ret = input_register_device(ts->dev);                                    //把这个input_dev添加到input系统中
}

ts底板图:

ts连到核心板图:

TSXP --> AIN7
TSYP --> AIN5





2.3 IRQ_PENDN

static irqreturn_t stylus_updown(int irqno, void *param)
{
    unsigned long data0;
    unsigned long data1;
    if (!ADC_locked4TS())                              //进入中断函数,如果没有加锁,则加上锁
        if (s3c_ts_adc_lock(LOCK_TS))                  //如果加锁失败,则直接返回       
            return IRQ_HANDLED;        
    data0 = readl(ts_base+S3C_ADCDAT0);
    data1 = readl(ts_base+S3C_ADCDAT1);
    touch_timer_fire(0);
    if(ts->s3c_adc_con==ADC_TYPE_2) {
         //ADCCLRINTPNDNUP: INT_PNDNUP interrupt clear
        __raw_writel(0x0, ts_base+S3C_ADCCLRWK);    
        //ADCCLRINT: Clear ADC Interrupt
        __raw_writel(0x0, ts_base+S3C_ADCCLRINT);   
    }
    return IRQ_HANDLED;
}

2.3.1 fire

static void touch_timer_fire(unsigned long data)
{
    unsigned long data0;
    unsigned long data1;
    int pendown;
    if (!ADC_locked4TS())                       //如果当前状态是free,说明加锁失败,直接返回
        return;
    
    //这儿的数据读取,是为了判断是down还是up状态
    data0 = readl(ts_base+S3C_ADCDAT0);         //读
    data1 = readl(ts_base+S3C_ADCDAT1);         //读   
    //data0的bit15: 0->按下状态; 1->松开状态
    //如果data0与data1都不为松开状态,就是按下状态
    pendown = (!(data0 & S3C_ADCDAT0_UPDOWN)) && (!(data1 & S3C_ADCDAT1_UPDOWN));
    if (pendown) {           //在按下状态,如果有数据则提交数据,      
        if (ts->count) {     //这个ts->count是在IRQ_ADC中改变的  
            input_report_abs(ts->dev, ABS_X, ts->xp);     //提交
            input_report_abs(ts->dev, ABS_Y, ts->yp);     //提交
            input_report_key(ts->dev, BTN_TOUCH, 1);       //提交
            input_report_abs(ts->dev, ABS_PRESSURE, 1);    //提交  
            input_sync(ts->dev);                           //提交
        }                      //ts->count>0,说明ADC己经转化过数据了,就提交完数据,  
        ts->xp = 0;            //然后把所有数据归零
        ts->yp = 0;
        ts->count = 0;
        //设ADC的模式为自动转换 
        writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base+S3C_ADCTSC);
        //ADCCON bit0 --> A/D conversion starts: 启动adc转换,产生一个IRQ_ADC中断
        //注意:这儿是要启动ADC中断,但具体是down还是up中断
        writel(readl(ts_base+S3C_ADCCON) | S3C_ADCCON_ENABLE_START, ts_base+S3C_ADCCON);  
    }
    else {                    //如果是松开
        ts->count = 0;
        input_report_key(ts->dev, BTN_TOUCH, 0);        //提交
        input_report_abs(ts->dev, ABS_PRESSURE, 0);     //提交
        input_sync(ts->dev);
        writel(WAIT4INT(0), ts_base+S3C_ADCTSC);    //等侍按下中断
        if (ADC_locked4TS())                       //如果还处于锁定状态
            s3c_ts_adc_unlock();                   //释放锁,表示一次按键结束
    }
}

注意: 
在按下状态,先提交数据,产生ADC中断,
在松开状态,先提交数据,切换为按下中断

2.4 IRQ_ADC
在进入IRQ_ADC中断之前,己经定义了一个时间定时器,它的处理函数是 touch_timer_fire

static struct timer_list touch_timer =
        TIMER_INITIALIZER(touch_timer_fire, 0, 0);

IRQ_ADC中断处理函数:

static irqreturn_t stylus_action(int irqno, void *param)
{
    unsigned long data0;
    unsigned long data1;
    if (!ADC_locked4TS()) {                        //如果处于未锁定状态,说明出错
        if (ADC_free())                            //锁是在IRQ_TS中加上的  
            __raw_writel(0x0, ts_base + S3C_ADCCLRINT);
        return IRQ_HANDLED;
    }
    data0 = readl(ts_base+S3C_ADCDAT0);            //读
    data1 = readl(ts_base+S3C_ADCDAT1);            //读
    if(ts->resol_bit==12) {
        ts->xp += data0 & S3C_ADCDAT0_XPDATA_MASK_12BIT;     //怎么能让我相信这是在求平均值呢?
        ts->yp += data1 & S3C_ADCDAT1_YPDATA_MASK_12BIT;
    }    
    ts->count++;
    if (ts->count < (1<<ts->shift)) {        //小于4次,ts->shift=2
        writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base+S3C_ADCTSC);
        writel(readl(ts_base+S3C_ADCCON) | S3C_ADCCON_ENABLE_START, ts_base+S3C_ADCCON);
    } else {                                 //超过4次,则    
        //启动定时器,把超时时间设为jiffies+1,调用touch_timer_fire
        mod_timer(&touch_timer, jiffies+1);
        //等侍松开            
        writel(WAIT4INT(1), ts_base+S3C_ADCTSC);
    }
    if(ts->s3c_adc_con==ADC_TYPE_2) {
        //ADCCLRINTPNDNUP: INT_PNDNUP interrupt clear
        __raw_writel(0x0, ts_base+S3C_ADCCLRWK);
        //ADCCLRINT: Clear ADC Interrupt
        __raw_writel(0x0, ts_base+S3C_ADCCLRINT);
    }
    return IRQ_HANDLED;
}

注意: 
在按下状态,先提交数据,产生ADC中断,
在松开状态,先提交数据,切换为按下中断

---

三.总结
3.1 按下到松开时的流程如下:


3.2 文字说明
初始化时设为等侍down中断模式
    当有触摸笔按下时:        
        a.触发中断,进入stylus_updown函数
            stylus_updown:判断是down中断, 如果ts->count,触发adc中断
        
        b.触发ADC中断,进入stylus_action函数
        stylus_action: ts->count小于4次, 触发adc中断; 
            继续自动检测,直到満足4次
        stylus_action:    时间定时器触发touch_timer_fire,并切换到等侍up中断模式
        c. touch_timer_fire:
                判断是down中断,汇报坐标信息,触发adc中断,与b进入循环
                持继汇报触摸笔按下信息
    当有触摸笔松开时:
        a. touch_timer_fire:
                判断是up中断,汇报坐标信息,切换到等侍按下中断