字符设备驱动之LED驱动

实现

①编写驱动框架

②编写硬件实现代码

（在Linux系统下操作硬件，需要操作虚拟地址，因此需要先把物理地址转换为虚拟地址 ioremap()）

如何实现单个灯的操作：

实现方法之一——操作次设备号

主设备号：用于查找对应的文件操作结构体；

次设备号：用于区分同类型设备下的不同设备；

 
 

 
 

实例

driver.c

1

12

14 ];
16

17

20

23         .open         .write         .owner };
28

29 static int myLED_open(struct
inode {
31                                    ;
35 }
36

37

38
{
41                  

44         copy_from_user(                  {
47                 :
48                                                  {
50                                                          }
52                                                                                   }
55                         

57                 :
58                                                  {
60                                                          }
62                                                                                   }
65                         

67                 :
68                                                  {
70                                                          }
72                                                                                   }
75                         

77                 default:

78                                                  {
80                                                          }
82                                                                                   }
85                         

87         }
88         ;
89 }
90

91 {
93         

95                  gpfcon );
97         gpfdat

99         major ,         myLED_class

102                  myLED_class_dev[] ),

105                  {
107                 myLED_class_dev[minor]         }
109         ;
110 }
111

112 {
114         

116                  iounmap(

119         unregister_chrdev(major,

121         class_device_unregister(myLED_class_dev[]);
122                  {
124                 myLED_class_dev[minor]         }
126         class_destroy(myLED_class);
127          }
129

130 module_init(myLED_init);
131 module_exit(myLED_exit);

 
 

app.c

1

6 {
8                                    
12         printf(                  {
15                 printf(                          }
18         
19         filename ];
20         
21         fd                  {
24                 printf(                          }
27         
28         ]))
29         {
30                 val                 write(fd, );
32         }
33         ]))
34         {        
35                 val                 write(fd, );
37         }
38         ;        
39 }

 
 

Makefile

1

3         make -C

6         make -C $(KERN_DIR) M=`pwd`
modules clean
8         rm -rf modules.order
9

10 obj-m
+= myLED.o