#include
#include
#include
#include
#include
#include
#include
#include
#include
#include //class_create
#include //S3C2410_GPF1
//#include
#include
//#include
#include //wait_event_interruptible
#include //poll
/* 定义并初始化等待队列头 */
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static struct class *fourthdrv_class;
static struct device *fourthdrv_device;
static struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
static struct pin_desc pins_desc[4] = {
{S3C2410_GPF1,0x01},
{S3C2410_GPF4,0x02},
{S3C2410_GPF2,0x03},
{S3C2410_GPF0,0x04},
};
static int ev_press = 0;
/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 /
/ 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;
int major;
/* 用户中断处理函数 */
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; /* 表示中断已经发生 */
wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
return IRQ_HANDLED;
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}
static int fourth_drv_open(struct inode * inode, struct file * filp)
{
/* K1 ---- EINT1,K2 ---- EINT4,K3 ---- EINT2,K4 ---- EINT0
* 配置GPF1、GPF4、GPF2、GPF0为相应的外部中断引脚
* IRQT_BOTHEDGE应该改为IRQ_TYPE_EDGE_BOTH
*/
request_irq(IRQ_EINT1, buttons_irq, IRQ_TYPE_EDGE_BOTH, “K1”,&pins_desc[0]);
request_irq(IRQ_EINT4, buttons_irq, IRQ_TYPE_EDGE_BOTH, “K2”,&pins_desc[1]);
request_irq(IRQ_EINT2, buttons_irq, IRQ_TYPE_EDGE_BOTH, “K3”,&pins_desc[2]);
request_irq(IRQ_EINT0, buttons_irq, IRQ_TYPE_EDGE_BOTH, “K4”,&pins_desc[3]);
return 0;
}
static ssize_t fourth_drv_read(struct file *file, char __user *user, size_t size,loff_t *ppos)
{
if (size != 1)
return -EINVAL;
/* 当没有按键按下时，休眠。
* 即ev_press = 0;
* 当有按键按下时，发生中断，在中断处理函数会唤醒
* 即ev_press = 1;
* 唤醒后，接着继续将数据通过copy_to_user函数传递给应用程序
*/
wait_event_interruptible(button_waitq, ev_press);
copy_to_user(user, &key_val, 1);
/* 将ev_press清零 */
ev_press = 0;
return 1;
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}
static int fourth_drv_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT1,&pins_desc[0]);
free_irq(IRQ_EINT4,&pins_desc[1]);
free_irq(IRQ_EINT2,&pins_desc[2]);
free_irq(IRQ_EINT0,&pins_desc[3]);
return 0;
}
static unsigned int fourth_drv_poll(struct file *file, poll_table *wait)
{
unsigned int mask = 0;
/* 该函数，只是将进程挂在button_waitq队列上，而不是立即休眠 */
poll_wait(file, &button_waitq, wait);
/* 当没有按键按下时，即不会进入按键中断处理函数，此时ev_press = 0
* 当按键按下时，就会进入按键中断处理函数，此时ev_press被设置为1
*/
if(ev_press)
{
mask |= POLLIN | POLLRDNORM; /* 表示有数据可读 */
}
/* 如果有按键按下时，mask |= POLLIN | POLLRDNORM,否则mask = 0 */
return mask;
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}
/* File operations struct for character device */
static const struct file_operations fourth_drv_fops = {
.owner = THIS_MODULE,
.open = fourth_drv_open,
.read = fourth_drv_read,
.release = fourth_drv_close,
.poll = fourth_drv_poll,
};
/* 驱动入口函数 /
static int fourth_drv_init(void)
{
/ 主设备号设置为0表示由系统自动分配主设备号 */
major = register_chrdev(0, “fourth_drv”, &fourth_drv_fops);
/* 创建fourthdrv类 */
fourthdrv_class = class_create(THIS_MODULE, "fourthdrv");
/* 在fourthdrv类下创建buttons设备，供应用程序打开设备*/
fourthdrv_device = device_create(fourthdrv_class, NULL, MKDEV(major, 0), NULL, "buttons");
return 0;
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}
/* 驱动出口函数 */
static void fourth_drv_exit(void)
{
unregister_chrdev(major, “fourth_drv”);
device_unregister(fourthdrv_device); //卸载类下的设备
class_destroy(fourthdrv_class); //卸载类
}
module_init(fourth_drv_init); //用于修饰入口函数
module_exit(fourth_drv_exit); //用于修饰出口函数
MODULE_AUTHOR(“LWJ”);
MODULE_DESCRIPTION(“Just for Demon”);
MODULE_LICENSE(“GPL”); //遵循GPL协议
/
#include
#include
#include
#include
#include
#include
/* fourth_test
*/
int main(int argc ,char *argv[])
{
int fd;
unsigned char key_val;
struct pollfd fds;
int ret;
fd = open("/dev/buttons",O_RDWR);
if (fd < 0)
{
printf("open error\n");
}
fds.fd = fd;
fds.events = POLLIN;
while(1)
{
/* A value of 0 indicates that the call timed out and no file descriptors were ready
* poll函数返回0时，表示5s时间到了，而这段时间里，没有事件发生"数据可读"
*/
ret = poll(&fds,1,5000);
if(ret == 0)
{
printf("time out\n");
}
else /* 如果没有超时，则读出按键值 */
{
read(fd,&key_val,1);
printf("key_val = 0x%x\n",key_val);
}
}
return 0;
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}
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版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
原文链接：https://blog.csdn.net/wenfengliaoshuzhai/article/details/131776859
