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2012-06-12 14:22:39

嵌入式Linux之我行,主要讲述和总结了本人在学习嵌入式linux中的每个步骤。一为总结经验,二希望能给想入门嵌入式Linux的朋友提供方便。如有错误之处,谢请指正。

一、移植环境

  • 主  机:VMWare--Fedora 9
  • 开发板:Mini2440--64MB Nand
  • 编译器:arm-linux-gcc-4.3.2

二、移植步骤

1. 准备驱动源码。因为linux-2.6.30.4内核中没有提供合适的ADC驱动和触摸屏驱动,所以这里就直接用友善提供的驱动
 
s3c24xx-adc.h

#ifndef _S3C2410_ADC_H_
#define _S3C2410_ADC_H_

#define ADC_WRITE(ch, prescale)    ((ch)<<16|(prescale))

#define ADC_WRITE_GETCH(data)    (((data)>>16)&0x7)
#define ADC_WRITE_GETPRE(data)    ((data)&0xff)

#endif /* _S3C2410_ADC_H_ */


mini2440_adc.c

#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 <linux/clk.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h>
    
#include <plat/regs-adc.h>
#include <mach/regs-gpio.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>

#include "s3c24xx-adc.h"

#undef DEBUG
//#define DEBUG

#ifdef DEBUG
#define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}
#else
#define DPRINTK(x...) (void)(0)
#endif

#define DEVICE_NAME    "adc"

static void __iomem *base_addr;

typedef struct {
    wait_queue_head_t wait;
    int channel;
    int prescale;
}ADC_DEV;

DECLARE_MUTEX(ADC_LOCK);
static int OwnADC = 0;

static ADC_DEV adcdev;
static volatile int ev_adc = 0;
static int adc_data;

static struct clk    *adc_clock;

#define ADCCON (*(volatile unsigned long *)(base_addr + S3C2410_ADCCON))    
//ADC control

#define ADCTSC (*(volatile unsigned long *)(base_addr + S3C2410_ADCTSC))    
//ADC touch screen control

#define ADCDLY (*(volatile unsigned long *)(base_addr + S3C2410_ADCDLY))    
//ADC start or Interval Delay

#define ADCDAT0 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDAT0))    
//ADC conversion data 0

#define ADCDAT1 (*(volatile unsigned long *)(base_addr + S3C2410_ADCDAT1))    
//ADC conversion data 1

#define ADCUPDN (*(volatile unsigned long *)(base_addr + 0x14))    
//Stylus Up/Down interrupt status

#define PRESCALE_DIS (0 << 14)
#define PRESCALE_EN (1 << 14)
#define PRSCVL(x) ((x) << 6)
#define ADC_INPUT(x) ((x) << 3)
#define ADC_START (1 << 0)
#define ADC_ENDCVT (1 << 15)

#define START_ADC_AIN(ch, prescale) \
    do{ \
        ADCCON = PRESCALE_EN | PRSCVL(prescale) | ADC_INPUT((ch)) ; \
        ADCCON |= ADC_START; \
    }while(0)

static irqreturn_t adcdone_int_handler(int irq, void *dev_id)
{
    if (OwnADC) {
        adc_data = ADCDAT0 & 0x3ff;

        ev_adc = 1;
        wake_up_interruptible(&adcdev.wait);
    }

    return IRQ_HANDLED;
}

static ssize_t s3c2410_adc_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
    char str[20];
    int value;
    size_t len;
    if (down_trylock(&ADC_LOCK) == 0) {
        OwnADC = 1;
        START_ADC_AIN(adcdev.channel, adcdev.prescale);
        wait_event_interruptible(adcdev.wait, ev_adc);

        ev_adc = 0;

        DPRINTK("AIN[%d] = 0x%04x, %d\n", adcdev.channel, adc_data, ADCCON & 0x80 ? 1:0);

        value = adc_data;
        sprintf(str,"%5d", adc_data);
        copy_to_user(buffer, (char *)&adc_data, sizeof(adc_data));

        OwnADC = 0;
        up(&ADC_LOCK);
    } else {
        value = -1;
    }

    len = sprintf(str, "%d\n", value);
    if (count >= len) {
        int r = copy_to_user(buffer, str, len);
        return r ? r : len;
    } else {
        return -EINVAL;
    }
}

static int s3c2410_adc_open(struct inode *inode, struct file *filp)
{
    init_waitqueue_head(&(adcdev.wait));

    adcdev.channel=0;
    adcdev.prescale=0xff;

    DPRINTK( "adc opened\n");
    return 0;
}

static int s3c2410_adc_release(struct inode *inode, struct file *filp)
{
    DPRINTK( "adc closed\n");
    return 0;
}

static struct file_operations dev_fops = {
    owner:    THIS_MODULE,
    open:    s3c2410_adc_open,
    read:    s3c2410_adc_read,    
    release:    s3c2410_adc_release,
};

static struct miscdevice misc = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &dev_fops,
};

static int __init dev_init(void)
{
    int ret;

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

    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);
    
    /* normal ADC */
    ADCTSC = 0;

    ret = request_irq(IRQ_ADC, adcdone_int_handler, IRQF_SHARED, DEVICE_NAME, &adcdev);
    if (ret) {
        iounmap(base_addr);
        return ret;
    }

    ret = misc_register(&misc);

    printk (DEVICE_NAME"\tinitialized\n");
    return ret;
}

static void __exit dev_exit(void)
{
    free_irq(IRQ_ADC, &adcdev);
    iounmap(base_addr);

    if (adc_clock) {
        clk_disable(adc_clock);
        clk_put(adc_clock);
        adc_clock = NULL;
    }

    misc_deregister(&misc);
}

EXPORT_SYMBOL(ADC_LOCK);
module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");

s3c2410_ts.c

#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 <linux/platform_device.h>
#include <linux/clk.h>
#include <asm/io.h>
#include <asm/irq.h>

#include <plat/regs-adc.h>
#include <mach/regs-gpio.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))

static char *s3c2410ts_name = "s3c2410 TouchScreen";

static    struct input_dev *dev;
static    long xp;
static    long yp;
static    int count;

extern struct semaphore ADC_LOCK;
static int OwnADC = 0;

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;

      data0 = ioread32(base_addr+S3C2410_ADCDAT0);
      data1 = ioread32(base_addr+S3C2410_ADCDAT1);

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

     if (updown) {
         if (count != 0) {
            long tmp;
                                                                                                 
            tmp = xp;
            xp = yp;
            yp = tmp;
                                                                                                 
            xp >>= 2;
            yp >>= 2;

#ifdef CONFIG_TOUCHSCREEN_MY2440_DEBUG
            struct timeval tv;
            do_gettimeofday(&tv);
            printk(KERN_DEBUG "T: %06d, X: %03ld, Y: %03ld\n", (int)tv.tv_usec, xp, yp);
#endif

             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;

         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 {
         count = 0;

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

         iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
        if (OwnADC) {
            OwnADC = 0;
            up(&ADC_LOCK);
        }
     }
}

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

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;
        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);
        } else {
            OwnADC = 0;
            up(&ADC_LOCK);
        }
    }

    return IRQ_HANDLED;
}

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);

        xp += data0 & S3C2410_ADCDAT0_XPDATA_MASK;
        yp += data1 & S3C2410_ADCDAT1_YPDATA_MASK;
        count++;

     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 {
            mod_timer(&touch_timer, jiffies+1);
            iowrite32(WAIT4INT(1), base_addr+S3C2410_ADCTSC);
        }
    }

    return IRQ_HANDLED;
}

static struct clk    *adc_clock;

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

    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);

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

    /* Configure GPIOs */
    s3c2410_ts_connect();

    iowrite32(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(0xFF),\
         base_addr+S3C2410_ADCCON);
    iowrite32(0xffff, base_addr+S3C2410_ADCDLY);
    iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);

    /* Initialise input stuff */
    input_dev = input_allocate_device();

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

    dev = input_dev;
    dev->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
    dev->keybit[BITS_TO_LONGS(BTN_TOUCH)] = BIT(BTN_TOUCH);
    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);

    dev->name = s3c2410ts_name;
    dev->id.bustype = BUS_RS232;
    dev->id.vendor = 0xDEAD;
    dev->id.product = 0xBEEF;
    dev->id.version = S3C2410TSVERSION;

    /* Get irqs */
    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 */
    input_register_device(dev);

    return 0;
}

static void __exit s3c2410ts_exit(void)
{
    disable_irq(IRQ_ADC);
    disable_irq(IRQ_TC);
    free_irq(IRQ_TC,dev);
    free_irq(IRQ_ADC,dev);

    if (adc_clock) {
        clk_disable(adc_clock);
        clk_put(adc_clock);
        adc_clock = NULL;
    }

    input_unregister_device(dev);
    iounmap(base_addr);
}

module_init(s3c2410ts_init);
module_exit(s3c2410ts_exit);

2. 部署驱动源代码到内核中

#cp -f s3c24xx-adc.h mini2440_adc.c /linux-2.6.30.4/drivers/char/

#cp -f s3c2410_ts.c /linux-2.6.30.4/drivers/input/touchscreen/


3. 将驱动模块添加到内核配置文件中
 

#gedit linux-2.6.30.4/drivers/char/Kconfig  //添加如下内容

config MY2440_ADC
    bool "ADC device for my2440"
    default y


#gedit linux-2.6.30.4/drivers/char/Makefile  //添加如下内容

obj-$(CONFIG_MY2440_ADC)  += mini2440_adc.o

#gedit linux-2.6.30.4/drivers/input/touchscreen/Kconfig  //添加如下内容

config TOUCHSCREEN_MY2440
    tristate "MY2440 touchscreens input driver"
    default y
 
config TOUCHSCREEN_MY2440_DEBUG
    boolean "MY2440 touchscreens input driver debug messages"
    depends on TOUCHSCREEN_MY2440
    help
        Select this if you want debug messages

#gedit linux-2.6.30.4/drivers/input/touchscreen/Makefile  //添加如下内容

obj-$(CONFIG_TOUCHSCREEN_MY2440) += s3c2410_ts.o

4. 修改内核配置选项
 

Device Drivers --->
    Input device support --->
        (240) Horizontal screen resolution
        (320) Vertical screen resolution
        [*] Touchscreens --->
            <*> MY2440 touchscreens input driver (NEW)
            [*] MY2440 touchscreens input driver debug messages
    Character devices --->
        [*] ADC device for my2440 (NEW)


5. 编译内核并下载到开发板上,从启动信息可以看到触摸屏驱动加载成功

6. 创建触摸屏设备节点并测试。由启动信息得知触摸屏设备为输入类设备,如下图操作可以得知输入类设备的主设备号为13,又查看总线的具体输入设备可得知该设备的详细信息,根据这些信息我们建立好设备节点,设置内核调试级别为8,然后打开触摸屏设备,点击触摸屏,此时可以看到打印的坐标信息,即触摸屏可正常使用了

 

 

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