中断按键控制

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/gpio.h>

#define DEVICE_NAME     "buttons"

struct button_irq_desc {
    int irq;
    int pin;
    int pin_setting;
    int number;
    char *name;	
};

static struct button_irq_desc button_irqs [] = {
    {IRQ_EINT8 , S3C2410_GPG(0) ,  S3C2410_GPG0_EINT8  , 0, "KEY0"},
    {IRQ_EINT11, S3C2410_GPG(3) ,  S3C2410_GPG3_EINT11 , 1, "KEY1"},
    {IRQ_EINT13, S3C2410_GPG(5) ,  S3C2410_GPG5_EINT13 , 2, "KEY2"},
    {IRQ_EINT14, S3C2410_GPG(6) ,  S3C2410_GPG6_EINT14 , 3, "KEY3"},
    {IRQ_EINT15, S3C2410_GPG(7) ,  S3C2410_GPG7_EINT15 , 4, "KEY4"},
    {IRQ_EINT19, S3C2410_GPG(11),  S3C2410_GPG11_EINT19, 5, "KEY5"},
};
static volatile char key_values [] = {'0', '0', '0', '0', '0', '0'};

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

static volatile int ev_press = 0;//按下为1


static irqreturn_t buttons_interrupt(int irq, void *dev_id)
{
    struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id;
    int down;

    // udelay(0);
    down = !s3c2410_gpio_getpin(button_irqs->pin);//读data数据寄存器取反,摁键按下为低电平0,但想用1来表示,所以取反

    if (down != (key_values[button_irqs->number] & 1)) { //key_values开始时为全0.当有键按下down=1,key_values[button_irqs->number]全0位与1等于0,down和key_values不相等.执行下面操作.Changed

	key_values[button_irqs->number] = '0' + down;//此步关键0+1将key_values值改变,当按键抬起down=0,key_values=1还要产生中断,因为此例使用双沿触发.
	
        ev_press = 1;//所以按下和弹起都认为有数据可以读,不仅ev_press = 1而且wake_up_interruptible唤醒进程.
        wake_up_interruptible(&button_waitq);//将没有读到按键键值而阻塞的进程唤醒
    }
    
    return IRQ_RETVAL(IRQ_HANDLED);//返回中断信息
}


static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{
    int i;
    int err = 0;
    
    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {//sizeof(button_irqs)/sizeof(button_irqs[0]=6,整个数组大小除以1个成员大小
	if (button_irqs[i].irq < 0) {
		continue;
	}
        err = request_irq(button_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH,//注册中断为多个按键使用for循环 ,IRQ_TYPE_EDGE_BOTH上升下降沿都中断,中断号button_irqs[i].irq不一样,但对应的中断处理程序一样
                          button_irqs[i].name, (void *)&button_irqs[i]);//button_irqs[i].name设备名, (void *)&button_irqs[i]是dev_id,使用其中的一个成员的地址使其唯一。此例没有使用共享中断
        if (err)
            break;
    }

    if (err) {
        i--;
        for (; i >= 0; i--) {
	    if (button_irqs[i].irq < 0) {
		continue;
	    }
	    disable_irq(button_irqs[i].irq);
            free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
        }
        return -EBUSY;
    }

    ev_press = 1;
    
    return 0;
}


static int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
    int i;
    
    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {
	if (button_irqs[i].irq < 0) {
	    continue;
	}
	free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
    }

    return 0;
}


static int s3c24xx_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
    unsigned long err;
	//在中断中ev_press被置1
    if (!ev_press) {//ev_press=0,表明没有按键按下,会阻塞，运行下行代码
	if (filp->f_flags & O_NONBLOCK)//判断用户是否使用O_NONBLOCK不阻塞,filp->f_flags是否设置O_NONBLOCK
	    return -EAGAIN;//有设置返回-EAGAIN
	else
	    wait_event_interruptible(button_waitq, ev_press);//没有O_NONBLOCK,设置阻塞,button_waitq等待队列,不严密中断可能将它打断
    }
    
    ev_press = 0;//数据读出后清零

    err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));//将按键键值key_values读走,通过键值知道对应哪个按键

    return err ? -EFAULT : min(sizeof(key_values), count);
}

static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait)//使用poll,先要指明要使用的等待队列,之后返回掩码
{
    unsigned int mask = 0;
    poll_wait(file, &button_waitq, wait);//使用poll_wait实现等待队列,button_waitq是等待队列
    if (ev_press)//通过全局变量去判断是否可读,初始值为0.1获得掩码按键按下
        mask |= POLLIN | POLLRDNORM;//ev_press为1返回可读掩码
    return mask;
}


static struct file_operations dev_fops = {
    .owner   =   THIS_MODULE,//
    .open    =   s3c24xx_buttons_open,//open中注册中断
    .release =   s3c24xx_buttons_close, 
    .read    =   s3c24xx_buttons_read,
    .poll    =   s3c24xx_buttons_poll,//多路监控
};

static struct miscdevice misc = {//struct miscdevice通常提供3个成员
	.minor = MISC_DYNAMIC_MINOR,//此设备号,MISC_DYNAMIC_MINOR动态获取255
	.name = DEVICE_NAME,//设备名字,自己填写
	.fops = &dev_fops,//字符设备重要的struct file_operations
};

static int __init dev_init(void)// 混杂设备注册,主设备号为10的一类字符设备
{
	int ret;

	ret = misc_register(&misc);//注册混杂设备,需要参数struct miscdevice结构的misc

	printk (DEVICE_NAME"\tinitialized\n");

	return ret;
}

static void __exit dev_exit(void)
{
	misc_deregister(&misc);
}

module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
/*在file_operations中.open打开文件的时候就注册中断
在open函数中,err = request_irq(button_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH,button_irqs[i].name, (void *)&button_irqs[i]);
注册中断处理函数buttons_interrupt.
中断处理函数中的寄存器会读清零
触发方式/* 设置中断触发方式 IRQ_TYPE_EDGE_FALLING,IRQ_TYPE_EDGE_RISING,
IRQ_TYPE_EDGE_BOTH ；