s3c2410觸摸屏驅動(2.6內核)分析

admin @ 2014-03-25 , reply:0

s3c2410觸摸屏驅動驅動不是很多,在此把它貼出來然後加上必要的註釋:

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <asm/irq.h>

#include <asm/arch/regs-adc.h>
#include <asm/arch/regs-gpio.h>
#include <asm/arch/s3c2410-ts.h>
#include <asm/hardware/clock.h>

/* For ts.dev.id.version */
#define S3C2410TSVERSION    0x0101

#define WAIT4INT(x) (((x)<<8) | S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN | S3C2410_ADCTSC_XP_SEN | S3C2410_ADCTSC_XY_PST(3))

#define AUTOPST (S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN | S3C2410_ADCTSC_XP_SEN | S3C2410_ADCTSC_AUTO_PST | S3C2410_ADCTSC_XY_PST(0))

#define DEBUG_LVL    KERN_DEBUG

MODULE_AUTHOR("Arnaud Patard <arnaud.patard@rtp-net.org>");
MODULE_DESCRIPTION("s3c2410 touchscreen driver");
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */


static char *s3c2410ts_name = "s3c2410 TouchScreen";

/*
 * Per-touchscreen data.
 */

struct s3c2410ts {
    struct input_dev dev;
    long xp;
    long yp;
    int count;
    int shift;
    char phys[32];
};

static struct s3c2410ts ts;
static void __iomem *base_addr;

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

      /*
        讀取stylus的狀態
        0 = Stylus down state
        1 = Stylus up state
       */
      data0 = readl(base_addr+S3C2410_ADCDAT0);
      data1 = readl(base_addr+S3C2410_ADCDAT1);

     updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT1_UPDOWN));
     /*
       更新stylus狀態寄存器updown:
       1 = down
       0 = up
      */
    /*
      touch_timer_fire這個函數主要實現以下功能:
      1、stylus down的時候,在中斷函數stylus_updown裡面被調用,
         此時緩存區沒有數據,ts.count為0,所以只是簡單的設置ad轉換的模式,然後開啟ad轉換。
      2、但ADC中斷函數stylus_action把緩衝區填滿的時候,作為中斷後半段函數稍後被調用,
         此時ts.count為4,算出其平均值后,交給事件處理層(Event Handler)處理,
         主要是填寫緩衝,然後喚醒等待輸入數據的進程。
      3、stylus抬起,等到緩衝區填滿后(可能會包含一些無用的數據)被調用,
         這時候判斷出stylus up,報告stylus up事件,重新等待stylus down。

     if (updown) {                       
         if (ts.count != 0) {    <功能2>
             /* 求平均值 */
             ts.xp >>= ts.shift;
             ts.yp >>= ts.shift;

#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
             {
                 struct timeval tv;
                 do_gettimeofday(&tv);
                 printk(DEBUG_LVL "T: %06d, X: %03ld, Y: %03ld ", (int)tv.tv_usec, ts.xp, ts.yp);
             }
#endif
             /* 報告x、y的絕對坐標值 */
             input_report_abs(&ts.dev, ABS_X, ts.xp);
             input_report_abs(&ts.dev, ABS_Y, ts.yp);

             /* 報告按鍵事件,鍵值為1(代表觸摸屏對應的按鍵被按下) */
             input_report_key(&ts.dev, BTN_TOUCH, 1);

             /* 報告觸摸屏的狀態,1表明觸摸屏被按下 */
             input_report_abs(&ts.dev, ABS_PRESSURE, 1);
      
             /* 等待接收方受到數據后回復確認,用於同步 */
             input_sync(&ts.dev);
         }
                                     <功能1>
         ts.xp = 0;
         ts.yp = 0;
         ts.count = 0;

         writel(S3C2410_ADCTSC_XP_PULL_UP_DIS | AUTOPST, base_addr+S3C2410_ADCTSC);
         /* 設置觸摸屏的模式為AUTOPST */
         writel(readl(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
         /* 啟動ADC轉換 */
     }
    else {                           <功能3>
    
         ts.count = 0;
        
         /* 報告按鍵事件,鍵值為1(代表觸摸屏對應的按鍵被釋放) */
         input_report_key(&ts.dev, BTN_TOUCH, 0);
        
         /* 報告觸摸屏的狀態,0表明觸摸屏沒被按下 */
         input_report_abs(&ts.dev, ABS_PRESSURE, 0);

         /* 等待接收方受到數據后回復確認,用於同步 */
         input_sync(&ts.dev);

         /* 進入s3c2410觸摸屏提供的,Waiting for Interrupt Mode,waits for Stylus down */
         writel(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
     }
}

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

static irqreturn_t stylus_updown(int irq, void *dev_id, struct pt_regs *regs)
{
    unsigned long data0;
    unsigned long data1;
    int updown;
    /*
       讀取ADCDAT0/1寄存器,判斷Stylus的狀態:
       0 = Stylus down state
       1 = Stylus up state
     */
    data0 = readl(base_addr+S3C2410_ADCDAT0);
    data1 = readl(base_addr+S3C2410_ADCDAT1);
   
    updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT1_UPDOWN));
    /*
      更新stylus狀態寄存器updown:
      1 = down
      0 = up
     */

    /* TODO we should never get an interrupt with updown set while
     * the timer is running, but maybe we ought to verify that the
     * timer isn't running anyways. */

    /* 判斷出stylus down,調用touch_timer_fire函數 */
    if (updown)
        touch_timer_fire(0);

    return IRQ_HANDLED;
}


static irqreturn_t stylus_action(int irq, void *dev_id, struct pt_regs *regs)
{
    unsigned long data0;
    unsigned long data1;
    data0 = readl(base_addr+S3C2410_ADCDAT0);
    data1 = readl(base_addr+S3C2410_ADCDAT1);

    /*
      觸摸屏的XY線接的是反的,所以只好這樣做了
      另外,可以參考這個方法:
      http://www.arm9bbs.com/redirect.php?tid=637&goto=lastpost
     */
    /**************************modify by lfc********************/
    ts.yp += data0 & S3C2410_ADCDAT0_XPDATA_MASK;
    ts.xp += data1 & S3C2410_ADCDAT1_YPDATA_MASK;
    /***********************************************************/
    ts.count++;
 
    if (ts.count < (1<<ts.shift)) {     
        /* 緩衝區未滿,再次激活ADC轉換 */
        writel(S3C2410_ADCTSC_XP_PULL_UP_DIS | AUTOPST, base_addr+S3C2410_ADCTSC);
        writel(readl(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
    } else {                             
        /* 緩衝區滿,激活下半部處理程序touch_timer_fire,處理接收數據 */
        mod_timer(&touch_timer, jiffies+1);
        writel(WAIT4INT(1), base_addr+S3C2410_ADCTSC);
    }

    return IRQ_HANDLED;
}

static struct clk    *adc_clock;

/*
 * The functions for inserting/removing us as a module.
 */

static int __init s3c2410ts_probe(struct device *dev)
{
    struct s3c2410_ts_mach_info *info;

    info = ( struct s3c2410_ts_mach_info *)dev->platform_data;
    註:
       s3c2410_ts_mach_info這個結構需要我們去填充,裡面存放的是觸摸屏需要的一些配置參數,見下面的附錄部分。

    if (!info)
    {
        printk(KERN_ERR "Hm... too bad : no platform data for ts ");
        return -EINVAL;
    }

#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
    printk(DEBUG_LVL "Entering s3c2410ts_init ");
#endif

    adc_clock = clk_get(NULL, "adc");
    if (!adc_clock) {
        printk(KERN_ERR "failed to get adc clock source ");
        return -ENOENT;
    }
    clk_use(adc_clock);//這個在高版本下已經不需要了
    clk_enable(adc_clock);

#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
    printk(DEBUG_LVL "got and enabled clock ");
#endif

    base_addr=ioremap(S3C2410_PA_ADC,0x20);//映射觸摸屏的控制寄存器,應該不需要解析了吧^_^
    if (base_addr == NULL) {
        printk(KERN_ERR "Failed to remap register block ");
        return -ENOMEM;
    }


    /* Configure GPIOs */
    s3c2410_ts_connect();
 
   /*以下根據我們提供的s3c2410_ts_mach_info結構,配置觸摸屏的一些控制寄存器*/
        /* Set the prscvl*/
    if ((info->presc&0xff) > 0)
        writel(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(info->presc&0xFF),
                 base_addr+S3C2410_ADCCON);
    else
        writel(0,base_addr+S3C2410_ADCCON);


    /* Initialise the adcdly registers */
    if ((info->delay&0xffff) > 0)
        writel(info->delay & 0xffff,  base_addr+S3C2410_ADCDLY);

    /* 進入s3c2410觸摸屏提供的Waiting for Interrupt Mode,waits for Stylus down.The controller generates Interrupt (INT_TC) signals when the Stylus is down on Touch Screen Panel.*/

    writel(WAIT4INT(0), base_addr+S3C2410_ADCTSC);

    /* Initialise input stuff */
    memset(&ts, 0, sizeof(struct s3c2410ts));
    /* 以下配置2.6內核劃分出來的輸入設備 */

    init_input_dev(&ts.dev);
    ts.dev.evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
    /*
       evbit欄位用來定義該輸入設備可以支持的(產生和響應)的事件的類型,
       在此觸摸屏設置為支持同步(EN_SYN)、按鍵(EN_KEY)、絕對坐標(EV_ABS)事件
    */
    ts.dev.keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
    /* 設置所支持的按鍵(鍵值),觸摸屏可以看成只有一個按鍵的設備 */

    input_set_abs_params(&ts.dev, ABS_X, 0, 0x3FF, 0, 0);
    /* 設置絕對坐標x的最小最大值,在這是0-0x3FF */

    input_set_abs_params(&ts.dev, ABS_Y, 0, 0x3FF, 0, 0);
    /* 設置絕對坐標y的最小最大值,在這是0-0x3FF */
    input_set_abs_params(&ts.dev, ABS_PRESSURE, 0, 1, 0, 0);

    sprintf(ts.phys, "ts0");

    ts.dev.private = &ts;
    ts.dev.name = s3c2410ts_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 = S3C2410TSVERSION;

    ts.shift = info->oversampling_shift;
    /*
       這個比較重要,配置輸入數據的緩存區大小,
       在這裡oversampling_shift設為2,也就是緩存區的大小為4(1<<2)
     */

    /* ADC轉換中斷,轉換結束后觸發 */
    if (request_irq(IRQ_ADC, stylus_action, SA_SAMPLE_RANDOM,
        "s3c2410_action", &ts.dev)) {
        printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_ADC ! ");
        iounmap(base_addr);
        return -EIO;
    }
    /*
       檢測stylus updown的中斷,設置為Waiting for Interrupt Mode時,
       The controller generates Interrupt (INT_TC) signals when the Stylus is down on Touch             Screen Panel,還記得吧^_^
     */
    if (request_irq(IRQ_TC, stylus_updown, SA_SAMPLE_RANDOM,
            "s3c2410_action", &ts.dev)) {
        printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_TC ! ");
        iounmap(base_addr);
        return -EIO;
    }

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

    /* All went ok, so register to the input system */
    input_register_device(&ts.dev);//註冊輸入設備

    return 0;
}
/* 好了,一切都準備好了,等待stylus updown的發生然後進入IRQ_TC中斷處理程序吧^_^ */

static int s3c2410ts_remove(struct device *dev)
{
    disable_irq(IRQ_ADC);
    disable_irq(IRQ_TC);
    free_irq(IRQ_TC,&ts.dev);
    free_irq(IRQ_ADC,&ts.dev);
    if (adc_clock) {
        clk_disable(adc_clock);
        clk_unuse(adc_clock);
        clk_put(adc_clock);
        adc_clock = NULL;
    }

    input_unregister_device(&ts.dev);
    iounmap(base_addr);

    return 0;
}

static struct device_driver s3c2410ts_driver = {
       .name           = "s3c2410-ts",
       .bus            = &platform_bus_type,
       .probe          = s3c2410ts_probe,
       .remove         = s3c2410ts_remove,
};


int __init s3c2410ts_init(void)
{
    return driver_register(&s3c2410ts_driver);
}

void __exit s3c2410ts_exit(void)
{
    driver_unregister(&s3c2410ts_driver);
}

module_init(s3c2410ts_init);
module_exit(s3c2410ts_exit);


附錄:
見/arch/arm/mach-s3c2410/dev.c文件:
static struct s3c2410_ts_mach_info sbc2410_ts_platdata = {
        .delay = 10000,
        .presc = 49,
        .oversampling_shift = 2,
        };

struct platform_device s3c_device_ts = {
        .name = "s3c2410-ts",
        .id = -1,
        .dev = {
                .platform_data = &sbc2410_ts_platdata,
        }
};
EXPORT_SYMBOL(s3c_device_ts);




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