驅(qū)動程序

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#includeinterrupt.h>
#include
#include
#include

#define DEV_NAME "qjz_buttons"http://DEV_NAME要與應用程序的open調(diào)用的NAME一樣
static int buttons_major,buttons_minor=0;//定義設備號
static struct cdev buttons_cdev;//定義設備結(jié)構(gòu)
static struct class *buttons_class;
static dev_t dev;

struct button_irq_desc
{
int irq;
int pin;
int pin_setting;
int number;
char *name;
};

static struct button_irq_desc button_irqs[ ]=
{
{IRQ_EINT1,S3C2410_GPF1,S3C2410_GPF1_EINT1,0,"KEY1"},
{IRQ_EINT4,S3C2410_GPF4,S3C2410_GPF4_EINT4,1,"KEY2"},
{IRQ_EINT2,S3C2410_GPF2,S3C2410_GPF2_EINT2,2,"KEY3"},
{IRQ_EINT0,S3C2410_GPF0,S3C2410_GPF0_EINT0,3,"KEY4"},
};
static volatile int key_values[]={0,0,0,0};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press = 0;

static irqreturn_t buttons_interrupt(int irq,void *dev_id)
{
struct button_irq_desc *button_irqs=(struct button_irq_desc *)dev_id;
int up = s3c2410_gpio_getpin(button_irqs->pin);
if(!up)
{
key_values[button_irqs->number]=(button_irqs->number+1);
}
ev_press = 1;
wake_up_interruptible(&button_waitq);
return IRQ_RETVAL(IRQ_HANDLED);
}

static int buttons_open(struct inode *inode,struct file *filp)
{
int i,err;
unsigned long irq_type;
irq_type=ioread32(S3C2410_EXTINT0);//設置中斷類型為上升沿
irq_type&=~(3<<1 | 3<<5 | 3<<9 | 3<<17 );
irq_type|=(3<<1 | 3<<5 | 3<<9 | 3<<17 );
iowrite32(irq_type,S3C2410_EXTINT0);
for(i = 0;i < 4; i++)
{
s3c2410_gpio_cfgpin(button_irqs[i].pin,button_irqs[i].pin_setting);
err = request_irq(button_irqs[i].irq, buttons_interrupt, NULL, button_irqs[i].name,(void*)&button_irqs[i]);
if(err)//成功返回值0，失敗返回一個負的錯誤碼
break;
}
if(err)//失敗就要釋放已經(jīng)注冊成功的中斷
{
i--;
for(;i>=0;i--)
{
disable_irq(button_irqs[i].irq);
free_irq(button_irqs[i].irq,(void*)&button_irqs[i]);
}
return -EBUSY;
}
return 0;
}
static int buttons_close(struct inode *inode,struct file *file)
{
int i;
for(i=0;i<4;i++)
{
disable_irq(button_irqs[i].irq);
free_irq(button_irqs[i].irq,(void*)&button_irqs[i]);
}
return 0;
}

static int buttons_read(struct file *filp,char __user *buff,size_t count,loff_t *offp)
{
unsigned long err;
if(!ev_press)
{
if(filp->f_flags & O_NONBLOCK)
return -EAGAIN;
else
wait_event_interruptible(button_waitq,ev_press);
}
ev_press = 0;
err=copy_to_user(buff,(const void*)key_values,count);
memset((void*)key_values,0,sizeof(key_values));
return err?-EFAULT:4;
}

static unsigned int buttons_poll(struct file *filp,poll_table *wait)
{
unsigned int mask = 0;
poll_wait(filp,&button_waitq,wait);
if(ev_press)
mask |=POLLIN|POLLRDNORM;
return mask;
}
static struct file_operations buttons_fops =
{
.owner = THIS_MODULE,
.open = buttons_open,
.release = buttons_close,
.read = buttons_read,
.poll = buttons_poll,
};

static int __init buttons_init(void)
{
int result;
if(buttons_major)
{
dev = MKDEV(buttons_major,buttons_minor);
result = register_chrdev_region(dev,1,DEV_NAME);
}
else
{
result = alloc_chrdev_region(&dev,buttons_minor,1,DEV_NAME);
buttons_major = MAJOR(dev);
}
if(result < 0)
{
printk(KERN_WARNING "buttons:cant get major %dn",buttons_major);
return result;
}
else
{
printk(KERN_WARNING"registered oknbuttons_major = %dn",buttons_major);
}
/*led_setup_cdev(&leds_cdev,0);*/
cdev_init(&buttons_cdev,&buttons_fops);
buttons_cdev.owner = THIS_MODULE;
buttons_cdev.ops = &buttons_fops;
result = cdev_add(&buttons_cdev,dev,1);
if(result < 0)
{
printk(KERN_WARNING"cdev_add failed!n");
return result;
}
else
{
printk(KERN_WARNING"cdev_add is ok!!n");
}
buttons_class = class_create(THIS_MODULE,DEV_NAME);
if(IS_ERR(buttons_class))
{
printk(KERN_ALERT"err:fail in buttons_class!n");
return -1;
}
else
{
printk(KERN_WARNING"SUCCESS IN buttons_CLASS!n");
}
class_device_create(buttons_class,NULL,MKDEV(buttons_major,0),NULL,DEV_NAME);
/*class_device_create(leds_class,NULL,dev,NULL,DEV_NAME);*/
printk(KERN_WARNING"buttons Module initialed!n");
return 0;
}

static void __exit buttons_exit(void)
{
int devno = MKDEV(buttons_major,buttons_minor);
unregister_chrdev_region(devno,1);
cdev_del(&buttons_cdev);
class_device_destroy(buttons_class,devno);
class_destroy(buttons_class);
printk(KERN_WARNING"buttons module exit!n");
}

module_init(buttons_init);
module_exit(buttons_exit);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("buttons device drver");
MODULE_AUTHOR("xxx");

應用程序

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

int main(void)
{
int i;
int buttons_fd;
int key_value[4];
buttons_fd=open("/dev/qjz_buttons",0);
if(buttons_fd < 0)
{
perror("open buttons fail");
exit(1);
}
for(;;)
{
fd_set reads;
int ret;
FD_ZERO(&reads);
FD_SET(buttons_fd,&reads);
ret = select(buttons_fd+1,&reads,NULL,NULL,NULL);
if(ret<0)
{
perror("select");
exit(1);
}
if(ret ==0)
{
printf("timeoutn");
}
else if(FD_ISSET(buttons_fd,&reads))
{
int ret=read(buttons_fd,key_value,sizeof(key_value));
printf("%dn",ret);
//if(ret !=sizeof(key_value))
//{
//if(errno !=EAGAIN)//教程中這里是有的，但是不知道為什么每次讀不出來按鍵值，屏蔽后，就可以讀出來！如圖！
//perror("read buttonsn");
//continue;
//}
//else
//{
for(i=0;i<4;i++)
{
if(key_value[i] !=0)
printf("K%d pressd,key value=0x%dn",i+1,key_value[i]);}
continue;
// }
}
}
close(buttons_fd);
return 0;
}

奶奶的，怎么按一次有的時候會出現(xiàn)多次按下去的情況那？還是驅(qū)動的問題！感覺應該是中斷的抖動造成的！關(guān)于如何去抖，要看看！

上面的應用程序用到了select，其實直接阻塞讀，就是直接read也可以得到按鍵值！我覺得select用在多輸入多輸出更有意義，也就是說用在多線程編程（例如聊天服務器里面的多點對多點，）。我不清楚用在這里是干什么?。菜聘M程的效率有關(guān)系）、直接阻塞讀，就是進程來讀，當沒有讀到數(shù)據(jù)就一直阻塞，一直到讀取到數(shù)據(jù)才返回！

按照網(wǎng)上的資料說的是：Select在Socket編程中還是比較重要的，可是對于初學Socket的人來說都不太愛用Select寫程序，他們只是習慣寫諸如connect、accept、recv或recvfrom這樣的阻塞程序（所謂阻塞方式block，顧名思義，就是進程或是線程執(zhí)行到這些函數(shù)時必須等待某個事件的發(fā)生，如果事件沒有發(fā)生，進程或線程就被阻塞，函數(shù)不能立即返回）?？墒鞘褂肧elect就可以完成非阻塞（所謂非阻塞方式non-block，就是進程或線程執(zhí)行此函數(shù)時不必非要等待事件的發(fā)生，一旦執(zhí)行肯定返回，以返回值的不同來反映函數(shù)的執(zhí)行情況，如果事件發(fā)生則與阻塞方式相同，若事件沒有發(fā)生則返回一個代碼來告知事件未發(fā)生，而進程或線程繼續(xù)執(zhí)行，所以效率較高）方式工作的程序，它能夠監(jiān)視我們需要監(jiān)視的文件描述符的變化情況——讀寫或是異常。

我覺得吧：像本例中在前面用到for循環(huán)，這樣就會照成select的效率低下！他也是一直循環(huán)的去檢查有沒有讀到數(shù)據(jù)。這豈不是跟阻塞讀差不多啦！

阻塞read應用程序如下：

#include
#include
#include
#include
#include
#include
#include
#include
#include

int main(void)
{
int i;
int buttons_fd;
int key_value[4];
buttons_fd=open("/dev/qjz_buttons",0);
if(buttons_fd < 0)
{
perror("open buttons fail");
exit(1);
}
for(;;)
{
read(buttons_fd,key_value,sizeof(key_value));

for(i=0;i<4;i++)
{
if(key_value[i] !=0)
printf("K%d pressd,key value=0x%dn",i+1,key_value[i]);}
continue;

}
close(buttons_fd);
return 0;
}