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

1. 1 在arch/arm/mach-s3c64xx/mach-smdk6410.c中
   2 static void __init smdk6410_machine_init(void)
   3 {
   4     //在arch/arm/mach-s3c64xx/dev-ts.c中
   5     s3c_ts_set_platdata(&s3c_ts_platform);                                  //1.设备私有信息的注册
   6     //在driver/base/platform.c中
   7     platform_add_devices(smdk6410_devices, ARRAY_SIZE(smdk6410_devices));   //2.设备资源的注册
   8 }

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

1.  1 static struct s3c_ts_mach_info s3c_ts_platform __initdata = {
    2     .delay               = 10000,                    //延时
    3     .presc               = 49,                       //分频
    4     .oversampling_shift  = 2,                        //分频
    5     .resol_bit           = 12,                       //精度
    6     .s3c_adc_con         = ADC_TYPE_2,               //分频
    7 };
    8 smdk6410_machine_init
    9 {
   10     //下面这个函数在arch/arm/mach-s3c64xx/dev-ts.c中
   11     s3c_ts_set_platdata(&s3c_ts_platform);
   12 }

1.2 ts设备资源的注册

1.  1 //在arch/arm/mach-s3c64xx/dev-ts.c中
    2 static struct resource s3c_ts_resource[] = {
    3     [0] = {
    4         .start = SAMSUNG_PA_ADC,                        //0x7E00B000
    5         .end = SAMSUNG_PA_ADC + SZ_256 - 1,             //0x7E00B100
    6         .flags = IORESOURCE_MEM,
    7     },
    8     [1] = {
    9         .start = IRQ_PENDN,                             //0x5e=94
   10         .end = IRQ_PENDN,
   11         .flags = IORESOURCE_IRQ,
   12     },
   13     [2] = {
   14         .start = IRQ_ADC,                                //0x5f=95
   15         .end = IRQ_ADC,
   16         .flags = IORESOURCE_IRQ,
   17     }
   18 };
   19 struct platform_device s3c_device_ts = {
   20     .name         = "s3c-ts",
   21     .id         = -1,
   22     .num_resources     = ARRAY_SIZE(s3c_ts_resource),
   23     .resource     = s3c_ts_resource,
   24 };
   25 //在arch/arm/mach-s3c64xx/mach-smdk6410.c中
   26 static struct platform_device *smdk6410_devices[] __initdata = {
   27     &s3c_device_ts,                //把ts放入到总的ts列表中
   28 }
   29 //在arch/arm/mach-s3c64xx/mach-smdk6410.c中
   30 static void __init smdk6410_machine_init(void)
   31 {
   32     //在driver/base/platform.c中一起注册
   33     platform_add_devices(smdk6410_devices, ARRAY_SIZE(smdk6410_devices));
   34 }

---

二. device_driver
2.0 两个宏

1.  1 #define WAIT4INT(x)              //只是针对于S3C_ADCTSC寄存器
    2         (((x)<<8) |              //<bit8> 0->down 1->up interrupt signal
    3         S3C_ADCTSC_YM_SEN |      //<bit7> 1 = Switch enable (YM = VSSA_ADC)
    4         S3C_ADCTSC_YP_SEN |      //<bit6> 1 = Switch disable (YP=AIN5, Hi-z)
    5         //XM_SEN                //<bit5> 0 = Switch disable (XM = AIN6, Hi-z)
    6         S3C_ADCTSC_XP_SEN |      //<bit4> 1 = Switch disable (XP=AIN7, Hi-z)
    7         //PULL_UP               //<bit3> 0 = XP Pull-up Enable.
    8         //AUTO_PST              //<bit2> 0 = Normal ADC conversion.
    9         S3C_ADCTSC_XY_PST(3))    //<bit1-0> 3: Waiting for Interrupt Mode
   10 #define AUTOPST
   11     (S3C_ADCTSC_YM_SEN |        //1 = Switch enable (YM = VSSA_ADC)
   12     S3C_ADCTSC_YP_SEN |         //1 = Switch disable (YP=AIN5, Hi-z)
   13     S3C_ADCTSC_XP_SEN |         //1 = Switch disable (XP=AIN7, Hi-z)
   14     S3C_ADCTSC_AUTO_PST |       //1 = Auto Sequential measurement of X-position, Y-position
   15     S3C_ADCTSC_XY_PST(0))       //0 = No operation mode
   16 WAIT4INT(x) :
   17             当x=0时,设为等侍down中断
   18              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

1. 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

1.  1 static int __init s3c_ts_probe(struct platform_device *pdev)
    2 {
    3     struct resource *res;
    4     struct device *dev;
    5     struct input_dev *input_dev;
    6     struct s3c_ts_mach_info * s3c_ts_cfg;
    7     int ret, size;
    8     dev = &pdev->dev;
    9     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);                //获取ts寄存器地址
   10     size = (res->end - res->start) + 1;
   11     ts_mem = request_mem_region(res->start, size, pdev->name);           //申请I/O内存
   12     ts_base = ioremap(res->start, size);                                 //request_mem_region申请的内存在使用前要调用ioremap
   13     ts_clock = clk_get(&pdev->dev, "adc");                               //获取clock
   14     clk_enable(ts_clock);                                                //在初始化时disable了ts_clock,这个地方要enable
   15
   16                                                                 //下面这几行是要把ts的配置信息写到寄存器中去
   17     s3c_ts_cfg = s3c_ts_get_platdata(&pdev->dev);                        //获取ts的配置信息,
   18                                                                          //ts的私有信息:在arch/arm/mach-s3c64xx/mach-smdk6410.c中
   19     //enable prescaler &&　设置prescaler_value=s3c_ts_cfg->presc
   20     writel(S3C_ADCCON_PRSCEN | S3C_ADCCON_PRSCVL(s3c_ts_cfg->presc&0xff), ts_base+S3C_ADCCON);
   21
   22    //s3c_ts_cfg->delay=0x10000 --> External input clock
   23     writel(s3c_ts_cfg->delay & 0xffff, ts_base+S3C_ADCDLY);
   24
   25     //A/D converter resolution selection--> 12-bit A/D conversion
   26     writel(readl(ts_base+S3C_ADCCON)|S3C_ADCCON_RESSEL_12BIT, ts_base+S3C_ADCCON);
   27     //设为等侍down中断模式
   28     writel(WAIT4INT(0), ts_base+S3C_ADCTSC);
   29     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
   30     input_dev = input_allocate_device();
   31
   32     ts->dev = input_dev;
   33     ts->dev->evbit[0] = ts->dev->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
   34     ts->dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
   35     if (s3c_ts_cfg->resol_bit==12) {
   36         input_set_abs_params(ts->dev, ABS_X, 0, 0xFFF, 0, 0);                //设置x轴的最大最小值
   37         input_set_abs_params(ts->dev, ABS_Y, 0, 0xFFF, 0, 0);                //设置y轴的最大最小值
   38     }
   39     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)
   40     sprintf(ts->phys, "input(ts)");
   41     ts->dev->name = s3c_ts_name;
   42     ts->dev->phys = ts->phys;
   43     ts->dev->id.bustype = BUS_RS232;
   44     ts->dev->id.vendor = 0xDEAD;
   45     ts->dev->id.product = 0xBEEF;
   46     ts->dev->id.version = S3C_TSVERSION;
   47     ts->shift = s3c_ts_cfg->oversampling_shift;
   48     ts->resol_bit = s3c_ts_cfg->resol_bit;
   49     ts->s3c_adc_con = s3c_ts_cfg->s3c_adc_con;
   50     /* For IRQ_PENDUP */
   51     ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);                //获取中断号
   52     //申请中断,RANDOM表示设备可以看作随机的发生源
   53     ret = request_irq(ts_irq->start, stylus_updown, IRQF_SAMPLE_RANDOM, "s3c_updown", ts); //申请中断
   54
   55     /* For IRQ_ADC */
   56     ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 1);               //获取中断号
   57     ret = request_irq(ts_irq->start, stylus_action, IRQF_SAMPLE_RANDOM | IRQF_SHARED, "s3c_action", ts); //申请共享中断
   58
   59     /* All went ok, so register to the input system */
   60     ret = input_register_device(ts->dev);                                    //把这个input_dev添加到input系统中
   61 }

ts底板图:

ts连到核心板图:

TSXP --> AIN7
TSYP --> AIN5

2.3 IRQ_PENDN

1.  1 static irqreturn_t stylus_updown(int irqno, void *param)
    2 {
    3     unsigned long data0;
    4     unsigned long data1;
    5     if (!ADC_locked4TS())                              //进入中断函数,如果没有加锁,则加上锁
    6         if (s3c_ts_adc_lock(LOCK_TS))                  //如果加锁失败,则直接返回
    7             return IRQ_HANDLED;
    8     data0 = readl(ts_base+S3C_ADCDAT0);
    9     data1 = readl(ts_base+S3C_ADCDAT1);
   10     touch_timer_fire(0);
   11     if(ts->s3c_adc_con==ADC_TYPE_2) {
   12          //ADCCLRINTPNDNUP: INT_PNDNUP interrupt clear
   13         __raw_writel(0x0, ts_base+S3C_ADCCLRWK);
   14         //ADCCLRINT: Clear ADC Interrupt
   15         __raw_writel(0x0, ts_base+S3C_ADCCLRINT);
   16     }
   17     return IRQ_HANDLED;
   18 }

2.3.1 fire

1.  1 static void touch_timer_fire(unsigned long data)
    2 {
    3     unsigned long data0;
    4     unsigned long data1;
    5     int pendown;
    6     if (!ADC_locked4TS())                       //如果当前状态是free,说明加锁失败,直接返回
    7         return;
    8
    9     //这儿的数据读取,是为了判断是down还是up状态
   10     data0 = readl(ts_base+S3C_ADCDAT0);         //读
   11     data1 = readl(ts_base+S3C_ADCDAT1);         //读
   12     //data0的bit15: 0->按下状态; 1->松开状态
   13     //如果data0与data1都不为松开状态,就是按下状态
   14     pendown = (!(data0 & S3C_ADCDAT0_UPDOWN)) && (!(data1 & S3C_ADCDAT1_UPDOWN));
   15     if (pendown) {           //在按下状态,如果有数据则提交数据,
   16         if (ts->count) {     //这个ts->count是在IRQ_ADC中改变的
   17             input_report_abs(ts->dev, ABS_X, ts->xp);     //提交
   18             input_report_abs(ts->dev, ABS_Y, ts->yp);     //提交
   19             input_report_key(ts->dev, BTN_TOUCH, 1);       //提交
   20             input_report_abs(ts->dev, ABS_PRESSURE, 1);    //提交
   21             input_sync(ts->dev);                           //提交
   22         }                      //ts->count>0,说明ADC己经转化过数据了,就提交完数据,
   23         ts->xp = 0;            //然后把所有数据归零
   24         ts->yp = 0;
   25         ts->count = 0;
   26         //设ADC的模式为自动转换
   27         writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base+S3C_ADCTSC);
   28         //ADCCON bit0 --> A/D conversion starts: 启动adc转换,产生一个IRQ_ADC中断
   29         //注意:这儿是要启动ADC中断,但具体是down还是up中断
   30         writel(readl(ts_base+S3C_ADCCON) | S3C_ADCCON_ENABLE_START, ts_base+S3C_ADCCON);
   31     }
   32     else {                    //如果是松开
   33         ts->count = 0;
   34         input_report_key(ts->dev, BTN_TOUCH, 0);        //提交
   35         input_report_abs(ts->dev, ABS_PRESSURE, 0);     //提交
   36         input_sync(ts->dev);
   37         writel(WAIT4INT(0), ts_base+S3C_ADCTSC);    //等侍按下中断
   38         if (ADC_locked4TS())                       //如果还处于锁定状态
   39             s3c_ts_adc_unlock();                   //释放锁,表示一次按键结束
   40     }
   41 }

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

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

IRQ_ADC中断处理函数:

1.  1 static irqreturn_t stylus_action(int irqno, void *param)
    2 {
    3     unsigned long data0;
    4     unsigned long data1;
    5     if (!ADC_locked4TS()) {                        //如果处于未锁定状态,说明出错
    6         if (ADC_free())                            //锁是在IRQ_TS中加上的
    7             __raw_writel(0x0, ts_base + S3C_ADCCLRINT);
    8         return IRQ_HANDLED;
    9     }
   10     data0 = readl(ts_base+S3C_ADCDAT0);            //读
   11     data1 = readl(ts_base+S3C_ADCDAT1);            //读
   12     if(ts->resol_bit==12) {
   13         ts->xp += data0 & S3C_ADCDAT0_XPDATA_MASK_12BIT;     //怎么能让我相信这是在求平均值呢?
   14         ts->yp += data1 & S3C_ADCDAT1_YPDATA_MASK_12BIT;
   15     }
   16     ts->count++;
   17     if (ts->count < (1<<ts->shift)) {        //小于4次,ts->shift=2
   18         writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base+S3C_ADCTSC);
   19         writel(readl(ts_base+S3C_ADCCON) | S3C_ADCCON_ENABLE_START, ts_base+S3C_ADCCON);
   20     } else {                                 //超过4次,则
   21         //启动定时器,把超时时间设为jiffies+1,调用touch_timer_fire
   22         mod_timer(&touch_timer, jiffies+1);
   23         //等侍松开
   24         writel(WAIT4INT(1), ts_base+S3C_ADCTSC);
   25     }
   26     if(ts->s3c_adc_con==ADC_TYPE_2) {
   27         //ADCCLRINTPNDNUP: INT_PNDNUP interrupt clear
   28         __raw_writel(0x0, ts_base+S3C_ADCCLRWK);
   29         //ADCCLRINT: Clear ADC Interrupt
   30         __raw_writel(0x0, ts_base+S3C_ADCCLRINT);
   31     }
   32     return IRQ_HANDLED;
   33 }

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