Linux中断异步通知笔记

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异步通知笔记

应用程序需要完成如下三个步骤：

1）signal(SIGIO, sig_handler);

调用signal函数，让指定的信号SIGIO与处理函数sig_handler对应。

2）fcntl(fd, F_SET_OWNER, getpid());

指定一个进程作为文件的“属主(filp->owner)”，这样内核才知道信号要发给哪个进程。

3）f_flags = fcntl(fd, F_GETFL);

fcntl(fd,F_SETFL, f_flags | FASYNC);

在设备文件中添加FASYNC标志，驱动中就会调用将要实现的test_fasync函数。

三个步骤执行后，一旦有信号产生，相应的进程就会收到。

内核需要完成下面四个步骤：

1）定义结构体fasync_struct。

static struct fasync_struct *button_async;

2）实现t fifth_drv_fasync，把函数fasync_helper将fd,filp和定义的结构体传给内核。

static int fifth_drv_fasync (int fd, struct file *filp, int on)

{

printk("driver:fifth_drv_fasync\n");

return fasync_helper (fd,filp, on, &button_async);

}

3）当设备可写时，调用函数kill_fasync发送信号SIGIO给内核。

kill_fasync(&button_async, SIGIO, POLL_IN);

4）完成ops

structfile_operations test_fops = {

.open =test_open,

.release =test_close,

.write =test_write,

.read =test_read,

.poll =test_poll,

.fasync =test_fasync

以下是部分代码

内核驱动代码

#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>

#include<linux/poll.h>

staticstruct class *fifthdrv_class;

staticstruct class_device *fifthdrv_class_dev;

volatileunsigned long *gpfcon;

volatileunsigned long *gpfdat;

volatileunsigned long *gpgcon;

volatileunsigned long *gpgdat;

staticDECLARE_WAIT_QUEUE_HEAD(button_waitq);

/*中断事件标志, 中断服务程序将它置1，fifth_drv_read将它清0 */

staticvolatile int ev_press = 0;

staticstruct fasync_struct *button_async;

structpin_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 */

staticunsigned char key_val;

structpin_desc pins_desc[4] = {

{S3C2410_GPF0, 0x01},

{S3C2410_GPF2, 0x02},

{S3C2410_GPG3, 0x03},

{S3C2410_GPG11, 0x04},

};

* 确定按键值

staticirqreturn_t buttons_irq(int irq, void *dev_id)

{

struct pin_desc * pindesc = (structpin_desc *)dev_id;

unsigned int pinval;

pinval =s3c2410_gpio_getpin(pindesc->pin);

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 */

kill_fasync (&button_async, SIGIO,POLL_IN);

return IRQ_RETVAL(IRQ_HANDLED);

}

staticint fifth_drv_open(struct inode *inode, struct file *file)

{

/* 配置GPF0,2为输入引脚 */

/* 配置GPG3,11为输入引脚 */

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_tfifth_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;

return 1;

}

intfifth_drv_close(struct inode *inode, struct file *file)

{

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]);

return 0;

}

staticunsigned fifth_drv_poll(struct file *file, poll_table *wait)

{

unsigned int mask = 0;

poll_wait(file, &button_waitq,wait); // 不会立即休眠

if (ev_press)

mask |= POLLIN | POLLRDNORM;

return mask;

}

staticint fifth_drv_fasync (int fd, struct file *filp, int on)

{

printk("driver:fifth_drv_fasync\n");

return fasync_helper (fd, filp, on,&button_async);

}

staticstruct 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 = fifth_drv_open,

.read = fifth_drv_read,

.release = fifth_drv_close,

.poll = fifth_drv_poll,

.fasync = fifth_drv_fasync,

};

intmajor;

staticint fifth_drv_init(void)

{

major = register_chrdev(0,"fifth_drv", &sencod_drv_fops);

fifthdrv_class =class_create(THIS_MODULE, "fifth_drv");

fifthdrv_class_dev =class_device_create(fifthdrv_class, NULL, MKDEV(major, 0), NULL,"buttons"); /* /dev/buttons */

gpfcon = (volatile unsigned long*)ioremap(0x56000050, 16);

gpfdat = gpfcon + 1;

gpgcon = (volatile unsigned long*)ioremap(0x56000060, 16);

gpgdat = gpgcon + 1;

return 0;

}

staticvoid fifth_drv_exit(void)

{

unregister_chrdev(major,"fifth_drv");

class_device_unregister(fifthdrv_class_dev);

class_destroy(fifthdrv_class);

iounmap(gpfcon);

iounmap(gpgcon);

return 0;

}

module_init(fifth_drv_init);

module_exit(fifth_drv_exit);

MODULE_LICENSE("GPL");

测试应用程序

#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>

/*fifthdrvtest

intfd;

voidmy_signal_fun(int signum)

{

unsigned char key_val;

read(fd, &key_val, 1);

printf("key_val: 0x%x\n",key_val);

}

intmain(int argc, char **argv)

{

unsigned char key_val;

int ret;

int Oflags;

signal(SIGIO, my_signal_fun);

fd = open("/dev/buttons",O_RDWR);

if (fd < 0)

{

printf("can'topen!\n");

}

fcntl(fd, F_SETOWN, getpid());

Oflags = fcntl(fd, F_GETFL);

fcntl(fd, F_SETFL, Oflags | FASYNC);

while (1)

{

sleep(1000);

}

return 0;

}

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