linux设备驱动初学(二)

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1. <div><span style='color: rgb(51, 51, 51); line-height: 25px; font-family: Georgia, "Times New Roman", Times, sans-serif; font-size: 14px;'>#include <linux/init.h></span></div><div><span style='color: rgb(51, 51, 51); line-height: 25px; font-family: Georgia, "Times New Roman", Times, sans-serif; font-size: 14px;'>#include <linux/kernel.h></span></div>#include <linux/module.h> 
2. #include <linux/types.h> 
3. #include <linux/fs.h> 
4. #include <linux/mm.h> 
5. #include <linux/errno.h> 
6. #include <asm/segment.h> 
7. #include <linux/module.h> 
8. #include <linux/sched.h> 
9. #include <linux/cdev.h> 
10. MODULE_LICENSE("Dual BSD/GPL"); 
11. unsigned int test_major=0; 
12. static char *book_name ="dissecting Linux Device Drviver"; 
13. static int num = 4000; 
14. static int global_major = 0; 
15. struct cc_dev_t 
16. { 
17.   struct cdev cdev; 
18. } cc_dev; 
19. static int cc_read(struct inode *inode,struct file *file,char *buf,int count) 
20. { 
21.     printk(KERN_INFO "*******cc_read********\n"); 
22.     return 0; 
23. } 
24. static int cc_write(struct inode *inode,struct file *file,constchar *buf,int count) 
25. { 
26.   printk(KERN_INFO "*******cc_write*******\n"); 
27.   return 0; 
28. } 
29. static int cc_open(struct inode *inode,struct file *file) 
30. { 
31.   printk(KERN_INFO "********cc_open*******\n"); 
32.   return 0; 
33. } 
34. static void cc_release(struct inode *inode,struct file *file) 
35. { 
36.   printk(KERN_INFO "*******cc_release*****\n"); 
37. } 
38. struct file_operations cc_fops={ 
39. .owner = THIS_MODULE, 
40. .read = cc_read, 
41. .write = cc_write, 
42. .open = cc_open, 
43. .release = cc_release, 
44. }; 
45. static int __init cc_init(void) 
46. { 
47.   int result,err; 
48.   dev_t devno = MKDEV(0,0); 
49.   result = alloc_chrdev_region(&devno,0,1,"cc"); 
50.   global_major = MAJOR(devno); 
51.   if(result < 0) 
52.   { 
53.     return result; 
54.   } 
55.   cdev_init(&cc_dev.cdev,&cc_fops); 
56.   err = cdev_add(&cc_dev.cdev,devno,1); 
57.   if(err) 
58.     printk(KERN_NOTICE "Error"); 
59.   return 0; 
60. } 
61. void cc_exit(void) 
62. { 
63.   cdev_del(&cc_dev.cdev); 
64.   unregister_chrdev_region(MKDEV(global_major,0),1); 
65. } 
66. module_init(cc_init); 
67. module_exit(cc_exit); 
68. module_param(num,int,S_IRUGO); 
69. module_param(book_name,charp,S_IRUGO); 
70. MODULE_AUTHOR("xyl"); 
71. MODULE_DESCRIPTION("A simple Hello world Moudle"); 
72. MODULE_ALIAS("a simplest moudle"); 
73. 写完驱动部分 make一下 在/proc/devices下面就会有对应的主设备号了 
74.  
75. makefile文件 
76.  
77.     PWD = $(shell pwd) 
78.     CC=gcc 
79.     KERNEL_SRC = /usr/src/linux-source-2.6.38/ 
80.     obj-m := cc.o 
81.     module-objs := cc.o 
82. all:    
83.     $(MAKE) -C $(KERNEL_SRC)  M=$(PWD) modules 
84. clean: 
85.     rm *.ko 
86.     rm *.o 
87. 之后在/dev下面创建设备节点  cat /proc/devices获得主设备号  mknod /dev/cc c major minor 
88.  
89. 在/dev下面就会有对应的设备节点了  如果想要删除的话直接rm掉 
90.  
91. 下面是test.c 
92.  
93. #include<stdio.h> 
94. #include<fcntl.h> 
95. int main() 
96. { 
97.   int myfile; 
98.   char buffer[100]; 
99.   int retval; 
100.   myfile = open("/dev/cc",O_RDWR); 
101.   if(myfile < 0) 
102.     printf("Open filed /n"); 
103.   write(myfile,"hello_world",sizeof("hello_world")); 
104.   retval = read(myfile,buffer,100); 
105.   buffer[retval] = 1; 
106.   printf("redponse:%s/n",buffer); 
107.   close(myfile); 
108. } 
109. 其中close对应驱动中的release.上面的 write read 内容就随便写啦，因为我驱动中并没有实现。 
110.  
111. 编译一下执行，看内核输出信息dmesg 如下 
112.  
113. [ 5096.422497] ********cc_open******* 
114. [ 5096.422512] *******cc_write******* 
115. [ 5096.422519] *******cc_read******** 
116. [ 5096.422572] *******cc_release***** 
117. 这样就说明调用成功了