6410之寫查詢方式的按鍵驅動

2021-06-16 14:49:09 字數 2583 閱讀 6789

查詢的方式獲取按鍵值驅動的步驟大致如下：

一、框架

1.file_operations的填充

2.入口函式註冊register_chrdev

3.修飾入口函式/出口函式

4.自動建立裝置節點

二、硬體操作

一、框架：

#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct class *buttons_class;


struct device *buttons_dev;


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


static ssize_t buttons_drv_read( struct file *file,


char __user *buffer,


size_t len,


loff_t *offset )


static struct file_operations buttons_fops = ;


int major;


static int __init buttons_drv_init(void)


static void __exit buttons_drv_exit(void)


module_init(buttons_drv_init);


module_exit(buttons_drv_exit);


module_license("gpl");
二、硬體操作：

檢視sch按鍵引腳對應的gpio如下：

keyint1----》gpn0

keyint2----》gpn1

keyint3----》gpn2

keyint4----》gpn3

keyint5----》gpn4

keyint6----》gpn5

open中配置為輸入引腳：gpncon &= ～0xfff 

沒有按下時為高電平，按下後是低電平

read中讀取引腳的狀態： state = （gpndat | 1 << x） ? 1 : 0;

驅動**如下：

#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct class *buttons_class;


struct device *buttons_dev;


volatile unsigned long *gpncon = null;


volatile unsigned long *gpndat = null;


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


static ssize_t buttons_drv_read( struct file *file,


char __user *buffer,


size_t len,


loff_t *offset )


int i;


for(i = 0 ; i < 6 ; i++)


copy_to_user(buffer,reg_val,sizeof(reg_val));


return sizeof(reg_val);


}static struct file_operations buttons_fops = ;


int major;


static int __init buttons_drv_init(void)


static void __exit buttons_drv_exit(void)


module_init(buttons_drv_init);


module_exit(buttons_drv_exit);


module_license("gpl");
測試程式： 

#include #include int main(int argc ,char **argv)


while(1)	}	


return 0;


}
這個是使用while迴圈的查詢方式進行讀取按鍵的值，

在驅動中的讀操作也一直處於一直讀的狀態，這樣會導致系統占用資源很多。

如下所示：

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