字符设备驱动程序——按键中断之异步通知

一、驱动程序的实现
1、定义static struct fasync_struct *newdrv_async;

2、加入
static struct file_operations new_drv_fops = {
.fasync =new_drv_fasync,
};
static int new_drv_fasync (int fd, struct file *filp, int on)
{
return fasync_helper (fd, filp, on, &newdrv_async);//初始化newdrv_async
}
3、发送信号
kill_fasync(&newdrv_async,SIGIO,POLL_IN);//发送信号，给newdrv_async

二、应用程序实现

	设置好目标设备的SIGIO信号处理函数;等待内核kill_fasync()释放 SIGIO 信号
signal(SIGIO,signal_fun);

	让设备中的信号发到当前进程；告诉内核（驱动程序）发给谁--本程序的pid
fcntl(fd,F_SETOWN,getpid());
	
	获得文件fd的flags，即open函数的第二个参数O_RDWR
oflags=fcntl(fd,F_GETFL);

	给设备文件fd添加异步通知模式，最终调用驱动的.fasync->fansync_help函数,初始化/释放,将fd加入异步IO通知队列
fcntl(fd,F_SETFL,oflags|FASYNC);

驱动程序

#include <linux/module.h>
#include <linux/sched.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 <linux/device.h>
#include <mach/gpio.h>
#include <linux/interrupt.h>
#include <linux/poll.h>

static struct class *newdrv_class;


volatile unsigned long *gpfcon = NULL;
volatile unsigned long *gpfdat = NULL;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

static unsigned char key;

static struct fasync_struct *newdrv_async;

struct pin_desc{
	unsigned int pin;//引脚
	unsigned int key_val;//键值,按下01 02 03 04；松开81 82 83 84
};

struct pin_desc pins_desc[4]={
	{S3C2410_GPF(0), 0x01},
	{S3C2410_GPF(2), 0x02},

};
	
static int 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);//读引脚
	if(pinval)//1 松开
	{
		key=0x80|pindesc->key_val;
	}
	else//按下
		key=pindesc->key_val;
		
	  kill_fasync(&newdrv_async,SIGIO,POLL_IN);//发送信号，给newdrv_async
	  
	return IRQ_RETVAL(IRQ_HANDLED);//接收到了中断信号,并处理，返回1
}


static int new_drv_open(struct inode *inode, struct file *file)
{
							/* 中断引脚			中断函数																	触发方式		名称	     传入dev—id */
	request_irq(IRQ_EINT0,  buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "S2", &pins_desc[0]);
	request_irq(IRQ_EINT2,  buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "S3", &pins_desc[1]);
	
	return 0;
}

static ssize_t new_drv_read(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
	if(count!=1)
		return -EINVA；

	copy_to_user(buf, &key, 1);

	return 1;
}

static int new_drv_close(struct inode *inode, struct file *file)
{
	free_irq(IRQ_EINT0, &pins_desc[0]);
	free_irq(IRQ_EINT2, &pins_desc[1]);

	return 0;
}

static int new_drv_fasync (int fd, struct file *filp, int on)
{
	return fasync_helper (fd, filp, on, &newdrv_async);//初始化newdrv_async
}

static struct file_operations new_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   =new_drv_open,     
	.read   =new_drv_read,
	.release=new_drv_close,
	.fasync   =new_drv_fasync,
};

int major;
static int new_drv_init(void)
{
	major = register_chrdev(0, "newdrv", &new_drv_fops); // 注册, 自动分配并返回主设备号
		/*在/sys/class/下创建类目录*/
	newdrv_class = class_create(THIS_MODULE, "newdrv");
		/*根据类目录，在驱动模块初始化函数中实现设备节点的自动创建*/
	device_create(newdrv_class, NULL, MKDEV(major, 0), NULL, "newdrv"); 

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

static void new_drv_exit(void)
{
	unregister_chrdev(major, "newdrv");
	device_destroy(newdrv_class, MKDEV(major, 0));
	class_destroy(newdrv_class);
	iounmap(gpfcon);
	
}

module_init(new_drv_init);
module_exit(new_drv_exit);


MODULE_LICENSE("GPL");

应用程序

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <poll.h>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>

int fd;

void signal_fun(int signum) //信号值-USR1
{
	unsigned char key_val,cnt;
	read(fd,&key_val,1);
	printf("signal=%d, %d times\n",signum,++cnt);
}

int main(int argc, char **argv)
{
	
	unsigned char key_val;
	int oflags;
	
	/*设置好目标设备的SIGIO信号处理函数;等待内核kill_fasync()释放 SIGIO 信号*/
	**signal(SIGIO,signal_fun);**
	
	fd = open("/dev/newdrv", O_RDWR);
	if(fd<0)
		printf("can't open\n");

	/*F_SETOWN：设置文件描述词fd上接收SIGIO 
				或 SIGURG事件信号的进程或进程组标识；
	  F_SETFL ：设置文件状态标志；
	  F_GETFL：读取文件状态标识
	*/

	/*让设备中的信号发到当前进程；告诉内核（驱动程序）发给谁--本程序的pid*/
	fcntl(fd,F_SETOWN,getpid());

	/*获得文件fd的flags，即open函数的第二个参数O_RDWR*/
	oflags=fcntl(fd,F_GETFL);
	
	/*给设备文件fd添加异步通知模式，最终调用驱动的.fasync->fansync_help函数,初始化/释放,将fd加入异步IO通知队列*/
	fcntl(fd,F_SETFL,oflags|FASYNC);
	
	while (1)
	{
		sleep(1000);
	}
	return 0;
}