linux驱动的异步通知（kill_fasync,fasync）---- 驱动程序向应用程序发送信号

应用程序

[cpp] view plain copy





#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

*/

int fd;

//信号处理函数

void my_signal_fun(int signum)

{

unsigned char key_val;

read(fd, &key_val, 1);

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

}

int main(int argc, char **argv)

{

unsigned char key_val;

int ret;

int Oflags;

//在应用程序中捕捉SIGIO信号（由驱动程序发送）

signal(SIGIO, my_signal_fun);

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

if (fd < 0)

{

printf("can't open!\n");

}

//将当前进程PID设置为fd文件所对应驱动程序将要发送SIGIO,SIGUSR信号进程PID

fcntl(fd, F_SETOWN, getpid());

//获取fd的打开方式

Oflags = fcntl(fd, F_GETFL);

//将fd的打开方式设置为FASYNC --- 即 支持异步通知

// 该行代码执行会触发 驱动程序中 file_operations->fasync 函数 ------fasync函数调用 fasync_helper初始化一个fasync_struct结构体，该结构体描述了将要发送信号的进程 PID (fasync_struct->fa_file->f_owner->pid)

fcntl(fd, F_SETFL, Oflags | FASYNC);

while (1)

{

sleep(1000);

}

return 0;

}

驱动程序

[cpp] view plain copy





#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>

static struct class *fifthdrv_class;

static struct class_device *fifthdrv_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，fifth_drv_read将它清0 */

static volatile int ev_press = 0;

static struct fasync_struct *button_async;

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GPG0，GPG3，GPG5，GPG6

*/

struct pin_desc pins_desc[4] = {

{S3C2410_GPG0, 0x01},

{S3C2410_GPG3, 0x02},

{S3C2410_GPG5, 0x03},

{S3C2410_GPG6, 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);

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 */

//发送信号SIGIO信号给fasync_struct 结构体所描述的PID，触发应用程序的SIGIO信号处理函数

kill_fasync (&button_async, SIGIO, POLL_IN);

return IRQ_RETVAL(IRQ_HANDLED);

}

static int fifth_drv_open(struct inode *inode, struct file *file)

{

/* GPG0，GPG3，GPG5，GPG6为中断引脚: EINT8,EINT11,EINT13,EINT14 */

request_irq(IRQ_EINT8, buttons_irq, IRQT_BOTHEDGE, "K1", &pins_desc[0]);

request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "K2", &pins_desc[1]);

request_irq(IRQ_EINT13, buttons_irq, IRQT_BOTHEDGE, "K3", &pins_desc[2]);

request_irq(IRQ_EINT14, buttons_irq, IRQT_BOTHEDGE, "K4", &pins_desc[3]);

return 0;

}

ssize_t fifth_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;

}

int fifth_drv_close(struct inode *inode, struct file *file)

{

free_irq(IRQ_EINT8, &pins_desc[0]);

free_irq(IRQ_EINT11, &pins_desc[1]);

free_irq(IRQ_EINT13, &pins_desc[2]);

free_irq(IRQ_EINT14, &pins_desc[3]);

return 0;

}

static unsigned 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;

}

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

{

printk("driver: fifth_drv_fasync\n");

//初始化/释放 fasync_struct 结构体 (fasync_struct->fa_file->f_owner->pid)

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

}

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 = fifth_drv_open,

.read = fifth_drv_read,

.release = fifth_drv_close,

.poll = fifth_drv_poll,

.fasync = fifth_drv_fasync,

};

int major;

static int 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;

return 0;

}

static void fifth_drv_exit(void)

{

unregister_chrdev(major, "fifth_drv");

class_device_unregister(fifthdrv_class_dev);

class_destroy(fifthdrv_class);

// iounmap(gpfcon);

return 0;

}

module_init(fifth_drv_init);

module_exit(fifth_drv_exit);

MODULE_LICENSE("GPL");
http://blog.csdn.net/psvoldemort/article/details/21184525