1 #include <linux/module.h> //MODULE_LICENSE("GPL");
2 #include <linux/init.h> //module_init module_exit
3 #include <linux/kernel.h> //printk
4 #include <linux/io.h> //ioremap iounremap
5 #include <linux/ioport.h> //request_mem_region
6
7
8 #include <linux/miscdevice.h>
9 #include <linux/fs.h> //file_operations 结构体的定义
10 #include <linux/slab.h> //kmalloc
11 #include <linux/delay.h>
12
13 #include <asm/uaccess.h> //copy_to_user copy_form_user
14
15 #include <linux/spinlock.h> //自旋锁
16
17 /*
18 该设备只能同时被一个进程打开
19 */
20
21
22 #define DEVNAME "my_led"
23 #define MEMSIZE 100
24
25 struct ldm_info
26 {
27 struct miscdevice dev; //设备节点
28 struct file_operations ops; //文件操作
29 unsigned char mem[MEMSIZE] ; //数组, 内核的空间
30 spinlock_t mylock; //自旋锁
31 };
32
33 //struct ldm_info ldm;
34 struct ldm_info ldm; //结构体的指针,分配空间
35
36 static int ldm_open(struct inode * inode, struct file * file)
37 {
38 printk("kernel: ldm_open\n");
39
40 return 0;
41 }
42
43 /*
44 copy_to_user
45 copy_form_user
46 */
47
48 static ssize_t ldm_write(struct file * file, const char __user * buf, size_t size, loff_t * offt)
49 {
50 int i =0;
51
52 spin_lock(&ldm.mylock);
53 //临界区开始
54
55 // if(!spin_trylock(&ldm.mylock)) {
56 // printk("当前资源被占用,请稍后\n");
57 // return -1;
58 // }
59
60 for(;i < size; i++) {
61 //每拷贝一个字节,睡眠1s
62 copy_from_user(ldm.mem + i, buf + i, 1);
63 printk("write:%c\n", ldm.mem[i]);
64 ssleep(1); //延迟1s
65 }
66 spin_unlock(&ldm.mylock);
67 //临界区结束
68
69 return 0;
70 }
71
72
73 ssize_t ldm_read(struct file * file, char __user * buf, size_t size, loff_t * offt)
74 {
75 //每隔一秒拷贝一个字节到用户层
76 int i =0;
77
78 spin_lock(&ldm.mylock);
79 // if(!spin_trylock(&ldm.mylock)) {
80 // printk("当前资源被占用,请稍后\n");
81 // return -1;
82 // }
83
84 for(;i < size; i++) {
85 //每拷贝一个字节,睡眠1s
86 copy_to_user(buf + i, ldm.mem + i, 1);
87 printk("read:%c\n", ldm.mem[i]);
88 ssleep(1); //延迟1s
89 }
90 spin_unlock(&ldm.mylock);
91
92
93 return 0;
94 }
95
96 int ldm_release(struct inode * inode, struct file *file)
97 {
98 printk("kernel: close\n");
99
100 return 0;
101 }
102
103 static int test_init(void)
104 {
105 int ret = 0;
106
107 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
108
109
110 ldm.dev.minor = MISC_DYNAMIC_MINOR; //系统自动分配次设备
111 ldm.dev.name = DEVNAME;//该名称将决定节点名称, 成功注册 linux 系统中
112 ldm.dev.fops = &ldm.ops; //关联文件操作
113 ldm.ops.open = ldm_open;
114 ldm.ops.write = ldm_write;
115 ldm.ops.read = ldm_read;
116 ldm.ops.release = ldm_release;
117
118
119 ret = misc_register(&ldm.dev);
120
121 spin_lock_init(&ldm.mylock);//初始化自旋锁
122
123 if(ret < 0) {
124 printk("misc_register failed\n");
125 goto err_misc_register;
126 }
127
128 return 0;
129 err_misc_register:
130 return ret;
131
132 }
133
134 //卸载
135 static void test_exit(void)
136 {
137 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
138
139
140 //注销misc
141 misc_deregister(&ldm.dev);
142 //释放映射的虚拟地址
143
144 }
145
146 module_init(test_init);
147 module_exit(test_exit);
148
149
150 MODULE_LICENSE("GPL"); //加入GPL许可
