按键驱动 的总结定时器防抖动 中断

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/time.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>

#define DEVICE_NAME "buttons" /* 加载模式后，执行”cat /proc/devices”命令看到的设备名称 */
unsigned char key_val;
static struct class *buttons_class;
static struct class_device    *buttons_class_devs;

/*
volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;

volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;
*/

/* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */
static volatile int ev_press = 0;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);



static DECLARE_MUTEX(button_lock); // 定义赋值
//static atomic_t canopen = ATOMIC_INIT(1); //定义原子变量并初始化为1


static struct timer_list buttons_timer;

struct pin_desc{
    int pin;        //4个引脚 GPF0 2  GPG3 GPG11
    int key_val;        //引脚对应置key_val值
};
struct pin_desc pins_desc[4]= //结构体只是一个类型 ， pins_desc是数组类似int a[3];
{
    {S3C2410_GPF0, 0x01},
    {S3C2410_GPF2, 0x02},
    {S3C2410_GPG3, 0x03},
    {S3C2410_GPG11, 0x04},
};

struct pin_desc *pindesc;

static irqreturn_t buttons_irq(int irq, void *dev_id)
{

        /* 10ms后启动定时器 */
    pindesc=(struct pin_desc *)dev_id;
    mod_timer(&buttons_timer, jiffies+HZ/100);
    return IRQ_RETVAL(IRQ_HANDLED);

}
static void buttons_timer_function(unsigned long data)
{

/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
int getpin;
getpin=s3c2410_gpio_getpin(pindesc->pin);//0按下 1放开
if(getpin)
{
//放开
key_val=0x80|pindesc->key_val;
}
else
{
//按下
key_val=pindesc->key_val;
}

    ev_press = 1;                            /* 表示中断发生了 */
    wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
}

static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{

#if 0
    if (!atomic_dec_and_test(&canopen))
    {
        atomic_inc(&canopen);
        return -EBUSY;
    }
#endif

    if (file->f_flags & O_NONBLOCK)
    {
        if (down_trylock(&button_lock))
            return -EBUSY;
    }
    else
    {
        /* 获取信号量 */
        down(&button_lock);
    }
    /* 配置GPF0,2,GPG3,11为输入引脚
       注册时，内核自动设置中断引脚
    */

    /*注册中断
      IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]分别为
      外部中断0  要执行的中断函数 双边沿触发  注册的中断  dev_id
    */
    request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);
    request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);
    request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);
    request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]);
    return 0;

}



ssize_t s3c24xx_buttons_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
    if (size != 1)
    return -EINVAL;

    if (file->f_flags & O_NONBLOCK)
    {
        if (!ev_press)
            return -EAGAIN;
    }
    else
    {
        /* 如果没有按键动作, 休眠 */
        wait_event_interruptible(button_waitq, ev_press);
    }

    copy_to_user(buf, &key_val, 1);
    ev_press = 0;
    return 1;
}


int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
    //atomic_inc(&canopen);
    free_irq(IRQ_EINT0, &pins_desc[0]);
    free_irq(IRQ_EINT2, &pins_desc[1]);
    free_irq(IRQ_EINT11, &pins_desc[2]);
    free_irq(IRQ_EINT19, &pins_desc[3]);
    up(&button_lock);
    return 0;
}

static struct file_operations s3c24xx_buttons_fops = {
    .owner = THIS_MODULE, /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open = s3c24xx_buttons_open,
    .read    =    s3c24xx_buttons_read,
    .release    =s3c24xx_buttons_close,
};

int ret;
static int __init s3c24xx_buttons_init(void)
{
    init_timer(&buttons_timer);
    buttons_timer.function = buttons_timer_function;
    //buttons_timer.expires = 0;
    add_timer(&buttons_timer);

    ret = register_chrdev(0, DEVICE_NAME, &s3c24xx_buttons_fops);
    if (ret < 0) {
      printk(DEVICE_NAME " can't register major number\n");
      return ret;
    }
    printk("%d",ret);
    buttons_class = class_create(THIS_MODULE, "buttons");
    buttons_class_devs= class_device_create(buttons_class, NULL, MKDEV(ret, 0), NULL, "buttons");
    //调试的时候老是出错就是因为MKDEV(ret, 0)，ret 按照LED  define  BUTTON_MAJOR  0  写成BUTTON_MAJOR，然后令其为0以为可以
    //自动配置主设备号，要注意此时MKDEV(ret, 0)不要写BUTTON_MAJOR  ret不是0是249（eg）
/*
        gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
    gpfdat = gpfcon + 1;

    gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
    gpgdat = gpgcon + 1;
         */
    printk(DEVICE_NAME " initialized\n");
    return 0;
}


static void __exit s3c24xx_buttons_exit(void)
{
    unregister_chrdev(ret, DEVICE_NAME);

    class_device_unregister(buttons_class_devs);
    class_destroy(buttons_class);
/*
    iounmap(gpfcon);
    iounmap(gpgcon);*/
}


module_init(s3c24xx_buttons_init);
module_exit(s3c24xx_buttons_exit);
MODULE_AUTHOR("");
MODULE_VERSION("0.1.0");
MODULE_DESCRIPTION("S3C2410/S3C2440 BUTTON Driver");
MODULE_LICENSE("GPL");