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研发客服通常开发板自带按键中断的驱动，中断已被注册至内核。重新编译linux内核去掉自带驱动才能使用自己编写的驱动。
linux中断程序可分解为顶半部与底半部机制。顶半部完成尽可能少的紧急功能，底半部可以被新的中断打断。
驱动程序
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define DEVICE_NAME 'key_device'
#define DEVICE_MAJOR 240
void key_tasklet_func(void);
DECLARE_TASKLET(key_tasklet,key_tasklet_func,0);
struct key_irq_desc
{
int irq;
int pin;
int pin_setting;
int number;
char *name;
};
static struct key_irq_desc key_irqs [] =
{
{IRQ_EINT(0), S3C64XX_GPN(0) , S3C64XX_GPN0_EINT0 , 0, 'KEY0'},
{IRQ_EINT(1), S3C64XX_GPN(1) , S3C64XX_GPN1_EINT1 , 1, 'KEY1'},
{IRQ_EINT(2), S3C64XX_GPN(2) , S3C64XX_GPN2_EINT2 , 2, 'KEY2'},
{IRQ_EINT(3), S3C64XX_GPN(3) , S3C64XX_GPN3_EINT3 , 3, 'KEY3'},
{IRQ_EINT(4), S3C64XX_GPN(4) , S3C64XX_GPN4_EINT4 , 4, 'KEY4'},
{IRQ_EINT(5), S3C64XX_GPN(5), S3C64XX_GPN5_EINT5 , 5, 'KEY5'},
};
static volatile int key_values [] = {1, 1, 1, 1, 1, 1};
//初始化等待列对
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int event_flag = 0;
static irqreturn_t buttons_interrupt(int irq, void *dev_id)
{
struct key_irq_desc *dev_irqs = (struct key_irq_desc *)dev_id;
int down;
down = gpio_get_value(dev_irqs->pin);
//按键发生了变化
if (down != (key_values[dev_irqs->number] & 1))
{
// Changed
key_values[dev_irqs->number] = 0 + down;
event_flag = 1;
//唤醒列对
wake_up_interruptible(&button_waitq);
}
tasklet_schedule(&key_tasklet);
return IRQ_RETVAL(IRQ_HANDLED);
}
void key_tasklet_func(void)
{
printk('<0>=======task========n');
printk('<0>task function test~n');
printk('<0>===================n');
}
static int s3c6410_key_open(struct inode *inode, struct file *file)
{
int i;
int err = 0;
//注册中断 结构体未注册完
for (i = 0; i < sizeof(key_irqs)/sizeof(key_irqs[0]); i++)
{
if (key_irqs[i].irq < 0)
{
continue;
}
// 中断号 中断处理寒酸 中断处理属性
err = request_irq(key_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH,
key_irqs[i].name, (void *)&key_irqs[i]);
if (err)
break;
}
//如果注册中断过程中出错，则注销注册成功的中断
if (err)
{
i--;
for (; i >= 0; i--)
{
if (key_irqs[i].irq < 0)
{
continue;
}
disable_irq(key_irqs[i].irq);
free_irq(key_irqs[i].irq, (void *)&key_irqs[i]);
}
return -EBUSY;
}
//显示一次主界面而已
event_flag = 1;
return 0;
}
static int s3c6410_keys_close(struct inode *inode, struct file *file)
{
int i;
//注销中断
for (i = 0; i < sizeof(key_irqs)/sizeof(key_irqs[0]); i++)
{
if (key_irqs[i].irq < 0)
{
continue;
}
free_irq(key_irqs[i].irq, (void *)&key_irqs[i]);
}
return 0;
}
static int s3c6410_keys_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
unsigned long err;
if (!event_flag)
{
//没有新按键事件处理，如果用户要求不阻塞就直接返回，否则阻塞在button_waitq队列上。
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
else
wait_event_interruptible(button_waitq, event_flag);
}
event_flag = 0;
err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));
return err ? -EFAULT : min(sizeof(key_values), count);
}
static struct file_operations key_device_fops =
{
.owner = THIS_MODULE,
.open = s3c6410_key_open,
.release = s3c6410_keys_close,
.read = s3c6410_keys_read,
};
static int __init key_device_init(void)
{
int ret;
printk ('<0>key initn');
//注册字符设备
ret = register_chrdev(DEVICE_MAJOR,DEVICE_NAME,&key_device_fops);
if (ret <0)
{
printk ('<0>register %s char dev errorn','key');
return -1;
}
printk ('<0>successn');
return 0;
}
static void __exit key_device_exit(void)
{
//注销设备
unregister_chrdev(DEVICE_MAJOR,DEVICE_NAME);
printk ('<0>module exitn');
}
module_init(key_device_init);
module_exit(key_device_exit);
MODULE_LICENSE('GPL');
MODULE_AUTHOR('hebaichuan');
测试程序，按6键退出死循环。
#include
#include
#include
#include
#define key_exit 5
int main(int argc, char **argv)
{
int fd,ret,i,key_value[6];
fd = open('/dev/key_device',0);
if(fd<0)
{
printf('open devie errorn');
return -1;
}
while(1)
{
ret = read(fd,key_value, sizeof(key_value));
if(ret<0)
{
printf('read errorn');
continue;
}
else if(!key_value[key_exit])
exit(0);
for(i=0;i<5;i++)
{
if(key_value[i])
{
printf('KEY%d releasedn',(i+1),key_value[i]);
}
else
{
printf('KEY%d pressed n',(i+1),key_value[i]);
}
}
printf('----------------key event----------------n');
}
close(fd);
return 0;
}
运行结果：
