乙個LED驅動的編寫

2021-08-02 23:34:46 字數 2569 閱讀 2557

#include 


#include 


#include 


#include 


#include 


#include 


#include 


#include


#include


#include


#include


#define gpm4con 0x110002e0


volatile


unsigned


long *baseaddr = 0; 


//位址必須要 volatile 修飾，volatile 是防止優化，就是避免某次計算中間值存放在暫存器中沒有存入flash，這會導致以後讀取的值不是想要的


#define rgpm4con (*((volatile unsigned long *)(baseaddr + 0)))


#define rgpm4dat (*((volatile unsigned long *)(baseaddr + 1)))


#define myled_major 0


#define myled_name "led"


#define myled_drvnum 1


#define myled_num 4


dev_t myled_devt; //裝置號


int myled_major;


struct


class *myled_class; //裝置結構體


struct cdev *myled; //裝置驅動核心結構


char led_status[myled_num]=;


loff_t led_lseek (struct file *fp, loff_t off, int whence)


if(newoff<0)


newoff = 0;


else


if(newoff>4)


newoff = 4;


fp->f_pos=newoff;


return newoff;


}ssize_t led_read (struct file *fp, char __user *buf, size_t size, loff_t *off)


ssize_t led_write (struct file *fp, const


char __user *buf, size_t size, loff_t *off)


*off = *off + size;


printk("led_write is called \n");


return0;}


int led_open (struct inode *node, struct file *fp)


int led_close (struct inode *node, struct file *fp)


struct file_operations led_fops=


;static


int __init myled_init(void) //形參不能為空


myled = cdev_alloc(); //分配裝置空間


/* 這裡多說兩句，每乙個裝置都是乙個結構體，這個結構體包括


struct kobject kobj; の，忘了幹嘛的


struct module *owner; 所屬的模組


const struct file_operations *ops; 所使用的檔案操作函式


struct list_head list; 鍊錶，向內和聯表新增


dev_t dev; 裝置號


unsigned int count; 裝置數目


*/cdev_init(myled,&led_fops); //初始化裝置 


/* 這個初始化這是把檔案函式結構體新增到裝置結構體


*/if(cdev_add(myled,myled_devt,myled_drvnum)) //新增裝置空間


printk("註冊成功\n");


myled_class = class_create(this_module,myled_name); //產生乙個裝置類


for(i=0;i//新增裝置類進核心


device_create(myled_class,null,myled_devt+i,null,"myled%d",i);


baseaddr = ioremap(gpm4con, 8); //硬體位址對映到虛擬位址


return0;}


static


void __exit myled_exit(void) //形參不能為空，必須有個void


module_init(myled_init);


module_exit(myled_exit);


module_license("gpl");

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