linux系統將設備分為3類：字符設備、塊設備、網絡設備。

設備驅動程序

 1 #include <linux/module.h>
 2 #include <linux/kernel.h>
 3 #include <linux/fs.h>
 4 #include <linux/init.h>
 5 #include <linux/delay.h>
 6 #include <asm/irq.h>
 7 #include <mach/regs-gpio.h>
 8 #include <mach/hardware.h>
 9
 
 #include <linux/device.h>
10 #include <linux/gpio.h>
11 
12 #define DEVICE_NAME    "mydriver"    

13 static int MYDRIVER_Major = 0;
14 
15 static int mydriver_open(struct inode *inode, struct file *file)
16 {
17     printk("My Driver Open Called!\n");
18     return 0;
19 }
20 
21 static int mydriver_release(struct
 
 inode *inode, struct file *file)
22 {
23     printk("My Driver Release Called!\n");
24     return 0;
25 }
26 
27 static int mydriver_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
28 {
29     printk("My Driver Read Called!\n");
30     return 0;
31 }
32 
33 static int mydriver_write(struct
 
 file *filp, char *buf, size_t count, loff_t *f_pos)
34 {
35     printk("My Driver Write Called!\n");
36     return 0;
37 }
38 
39 static int mydriver_ioctl( struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
40 {
41 
42 }
43 
44 static struct file_operations mydriver_fops =
45 {
46     .owner  =   THIS_MODULE,
47     .open   =   mydriver_open, 
48     .release =  mydriver_release,
49     .read   =   mydriver_read,
50     .write  =   mydriver_write,
51     .ioctl  =   mydriver_ioctl,
52 };
53 
54 static struct class *mydriver_class;
55 
56 static int __init mydriver_init(void)
57 {
58 
59     printk("MY DRIVER MODULE INIT\n");
60 
61     MYDRIVER_Major = register_chrdev(0, DEVICE_NAME, &mydriver_fops);
62     if (MYDRIVER_Major < 0)
63     {
64         printk(DEVICE_NAME " can‘t register major number\n");
65         return MYDRIVER_Major;
66     }
67     printk("register My Driver OK! Major = %d\n", MYDRIVER_Major);
68 
69     //註冊一個類，使mdev可以在"/dev/"目錄下面建立設備節點
70     mydriver_class = class_create(THIS_MODULE, DEVICE_NAME);
71     if(IS_ERR(mydriver_class))
72     {
73         printk("Err: failed in My Driver class. \n");
74         return -1;
75     }
76     //創建一個設備節點，節點名為DEVICE_NAME
77     device_create(mydriver_class, NULL, MKDEV(MYDRIVER_Major, 0), NULL, DEVICE_NAME);
78 
79     printk(DEVICE_NAME " initialized\n");
80     return 0;
81 }
82 
83 static void __exit mydriver_exit(void)
84 {
85     printk("MY DRIVER MODULE EXIT\n");
86     unregister_chrdev(MYDRIVER_Major, DEVICE_NAME);
87     device_destroy(mydriver_class, MKDEV(MYDRIVER_Major, 0));
88     class_destroy(mydriver_class);
89 }
90 
91 module_init(mydriver_init);
92 module_exit(mydriver_exit);
93 
94 MODULE_AUTHOR("www.txmcu.com");        
95 MODULE_DESCRIPTION("My Driver");    
96 MODULE_LICENSE("GPL");

測試應用程序

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <unistd.h>
 4 #include <sys/ioctl.h>
 5 
 6 int main(int argc, char **argv)
 7 {
 8     int fd;
 9     fd = open("/dev/XXXX", 0);
10     if (fd < 0)
11     {
12         perror("open device");
13         exit(1);
14     }
15 
16     /*your code*/
17 
18     close(fd);
19     return 0;
20 }

Linux - 字符設備驅動helloword