概述
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_fasyncn");
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_fasyncn");
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%xn",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;
}
最后
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