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 #include <linux/rwlock.h> //读写自旋锁
17 #include <linux/semaphore.h>
18
19 /*
20 该设备只能同时被一个进程打开
21 */
22
23
24 #define DEVNAME "my_led"
25 #define MEMSIZE 100
26
27
28 int test = 1;
29
30 struct ldm_info
31 {
32 struct miscdevice dev; //设备节点
33 struct file_operations ops; //文件操作
34 unsigned char mem[MEMSIZE] ; //数组, 内核的空间
35 //rwlock_t myrwlock;
36 struct semaphore sema;
37 };
38
39 //struct ldm_info ldm;
40 struct ldm_info ldm; //结构体的指针,分配空间
41
42 static int ldm_open(struct inode * inode, struct file * file)
43 {
44 //printk("kernel: ldm_open\n");
45 test++;
46 //如何传递私有变量
47 //Linux任何一个文件,都会有一个file指针,
48 //有一个成员 private_data void * 通用指针
49 file->private_data = (void *)&test;
50
51 return 0;
52 }
53
54 /*
55 copy_to_user
56 copy_form_user
57 */
58
59 static ssize_t ldm_write(struct file * file, const char __user * buf, size_t size, loff_t * offt)
60 {
61 int i =0;
62
63 int val = *(int *)file->private_data;
64
65 //write_lock(&ldm.myrwlock);
66 down(&ldm.sema);
67 for(;i < size; i++) {
68 //每拷贝一个字节,睡眠1s
69 copy_from_user(ldm.mem + i, buf + i, 1);
70 printk("write:%c val = %d\n", ldm.mem[i], val);
71 ssleep(1); //延迟1s
72 }
73 //write_unlock(&ldm.myrwlock);
74 up(&ldm.sema);
75
76
77 return 0;
78 }
79
80
81 ssize_t ldm_read(struct file * file, char __user * buf, size_t size, loff_t * offt)
82 {
83 //每隔一秒拷贝一个字节到用户层
84 int i =0;
85
86 int val = *(int *)file->private_data;
87
88 //read_lock(&ldm.myrwlock);
89 down(&ldm.sema);
90 for(;i < size; i++) {
91 //每拷贝一个字节,睡眠1s
92 copy_to_user(buf + i, ldm.mem + i, 1);
93 printk("read:%c, val = %d\n", ldm.mem[i], val);
94 ssleep(1); //延迟1s
95 }
96 //read_unlock(&ldm.myrwlock);
97 up(&ldm.sema);
98 return 0;
99 }
100
101 int ldm_release(struct inode * inode, struct file *file)
102 {
103 //printk("kernel: close\n");
104 test--;
105 return 0;
106 }
107
108 static int test_init(void)
109 {
110 int ret = 0;
111
112 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
113
114
115 ldm.dev.minor = MISC_DYNAMIC_MINOR; //系统自动分配次设备
116 ldm.dev.name = DEVNAME;//该名称将决定节点名称, 成功注册 linux 系统中
117 ldm.dev.fops = &ldm.ops; //关联文件操作
118 ldm.ops.open = ldm_open;
119 ldm.ops.write = ldm_write;
120 ldm.ops.read = ldm_read;
121 ldm.ops.release = ldm_release;
122
123
124 ret = misc_register(&ldm.dev);
125
126 //rwlock_init(&ldm.myrwlock);
127 sema_init(&ldm.sema, 1);
128
129 if(ret < 0) {
130 printk("misc_register failed\n");
131 goto err_misc_register;
132 }
133
134 return 0;
135 err_misc_register:
136 return ret;
137
138 }
139
140 //卸载
141 static void test_exit(void)
142 {
143 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
144
145
146 //注销misc
147 misc_deregister(&ldm.dev);
148 //释放映射的虚拟地址
149
150 }
151
152 module_init(test_init);
153 module_exit(test_exit);
154
155
156 MODULE_LICENSE("GPL"); //加入GPL许可
