按键中断，休眠，唤醒

中断编写流程：

1.在对按键节点进行open操作的时候来申请中断：

request_irq(IRQ_EINT1, buttons_irq, IRQT_BOTHEDGE, "K1", &pins_desc[0]);

IRQ_EINT1 :中断号

buttons_irq :中断处理函数

IRQT_BOTHEDGE:中断的标志，表示在上升沿或下降沿都可以触发

pin_desc:这是一个可选项，用于传到中断处理函数的参数dev_id

 

2.当按键按下就会调用到中断处理函数.

static irqreturn_t buttons_irq(int irq, void *dev_id) ===> 按键按下所要做的工作。

 

休眠唤醒：

休眠唤醒的引入是为了给cpu节省资源。

使用方法：

1.定义等待队列：

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);//定义个一个button_waitq队列

DECLARE_WAIT_QUEUE_HEAD是一个宏，它的定义如下：

#define DECLARE_WAIT_QUEUE_HEAD(name) \
	wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)

相当于：

wait_queue_head_t button_waitq = {    
 .lock  = __SPIN_LOCK_UNLOCKED(button_waitq.lock),  \
 .task_list = { &(button_waitq).task_list, &(button_waitq).task_list } }

/* 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;

2.当中断发生，在中断处理函数中唤醒进程：

static irqreturn_t buttons_irq(int irq, void *dev_id)
{
 struct pin_desc * pindesc = (struct pin_desc *)dev_id;
 unsigned int pinval;
 
 pinval = s3c2410_gpio_getpin(pindesc->pin);// 获取引脚的状态，1为松开，0为按下

 if (pinval)
 {
  /* 松开 */
  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 */

 
 return IRQ_RETVAL(IRQ_HANDLED);
}

唤醒休眠进程后就可以进行读操作了：

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

 /* 如果没有按键动作, 休眠 */
 wait_event_interruptible(button_waitq, ev_press);//会先判断是否休眠，ev_press = 1表示进程被唤醒，ev_pree == 0表示进程处于休眠的状态

 /* 如果有按键动作, 返回键值 */
 copy_to_user(buf, &key_val, 1);
 ev_press = 0;//这个ev_press是个全局变量，在键值传送到用户空间后，清0，进入休眠状态
 
 return 1;
}

完整程序如下：

#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 <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>


static struct class *thirddrv_class;
static struct class_device	*thirddrv_class_dev;

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

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

/* 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;


struct pin_desc{
	unsigned int pin;
	unsigned int key_val;
};


/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;

/*
 * K1,K2,K3,K4对应GPF1、GPF4、GPF2、GPF0
 */

struct pin_desc pins_desc[4] = {
	{S3C2410_GPF1, 0x01},//S3C2410_GPF1为引脚的编号
	{S3C2410_GPF4, 0x02},
	{S3C2410_GPF2, 0x03},
	{S3C2410_GPF0, 0x04},
};


/*
  * 确定按键值
  */
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
	struct pin_desc * pindesc = (struct pin_desc *)dev_id;
	unsigned int pinval;
	
	pinval = s3c2410_gpio_getpin(pindesc->pin);// 获取引脚的状态，1为松开，0为按下

	if (pinval)
	{
		/* 松开 */
		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 */

	
	return IRQ_RETVAL(IRQ_HANDLED);
}

static int third_drv_open(struct inode *inode, struct file *file)
{
	/* GPF1、GPF4、GPF2、GPF0为中断引脚 */
	request_irq(IRQ_EINT1, buttons_irq, IRQT_BOTHEDGE, "K1", &pins_desc[0]);
	request_irq(IRQ_EINT4, buttons_irq, IRQT_BOTHEDGE, "K2", &pins_desc[1]);
	request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "K3", &pins_desc[2]);
	request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "K4", &pins_desc[3]);	

	return 0;
}

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

	/* 如果没有按键动作, 休眠 */
	wait_event_interruptible(button_waitq, ev_press);

	/* 如果有按键动作, 返回键值 */
	copy_to_user(buf, &key_val, 1);
	ev_press = 0;//清0
	
	return 1;
}


int third_drv_close(struct inode *inode, struct file *file)
{
	free_irq(IRQ_EINT1, &pins_desc[0]);
	free_irq(IRQ_EINT4, &pins_desc[1]);
	free_irq(IRQ_EINT2, &pins_desc[2]);
	free_irq(IRQ_EINT0, &pins_desc[3]);
	return 0;
}


static struct file_operations sencod_drv_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    =  third_drv_open,     
	.read	 =	third_drv_read,	   
	.release =  third_drv_close,	   
};


int major;
static int third_drv_init(void)
{
	major = register_chrdev(0, "third_drv", &sencod_drv_fops);

	thirddrv_class = class_create(THIS_MODULE, "third_drv");

	thirddrv_class_dev = class_device_create(thirddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */

//	gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
//	gpfdat = gpfcon + 1;

	return 0;
}

static void third_drv_exit(void)
{
	unregister_chrdev(major, "third_drv");
	class_device_unregister(thirddrv_class_dev);
	class_destroy(thirddrv_class);
//	iounmap(gpfcon);
	return 0;
}


module_init(third_drv_init);

module_exit(third_drv_exit);

MODULE_LICENSE("GPL");