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/seqlock.h> //顺序锁
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 seqlock_t seq;
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 write_seqlock(&ldm.seq);
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 write_sequnlock(&ldm.seq);
75
76 return 0;
77 }
78
79
80 ssize_t ldm_read(struct file * file, char __user * buf, size_t size, loff_t * offt)
81 {
82 //每隔一秒拷贝一个字节到用户层
83 int i =0;
84
85 int val = *(int *)file->private_data;
86
87 int seq = 0;
88 do {
89 seq = read_seqbegin(&ldm.seq);
90 //printk("seq = %d\n", seq);
91
92 for(;i < size; i++) {
93 //seq = read_seqbegin(&ldm.seq);
94 //每拷贝一个字节,睡眠1s
95 copy_to_user(buf + i, ldm.mem + i, 1);
96 printk("read:%c, val = %d\n", ldm.mem[i], val);
97 ssleep(1); //延迟1s
98 }
99 }while(read_seqretry(&ldm.seq, seq));
100
101 return 0;
102 }
103
104 int ldm_release(struct inode * inode, struct file *file)
105 {
106 //printk("kernel: close\n");
107 test--;
108 return 0;
109 }
110
111 static int test_init(void)
112 {
113 int ret = 0;
114
115 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
116
117
118 ldm.dev.minor = MISC_DYNAMIC_MINOR; //系统自动分配次设备
119 ldm.dev.name = DEVNAME;//该名称将决定节点名称, 成功注册 linux 系统中
120 ldm.dev.fops = &ldm.ops; //关联文件操作
121 ldm.ops.open = ldm_open;
122 ldm.ops.write = ldm_write;
123 ldm.ops.read = ldm_read;
124 ldm.ops.release = ldm_release;
125
126
127 ret = misc_register(&ldm.dev);
128
129 //rwlock_init(&ldm.myrwlock);
130 seqlock_init(&ldm.seq);
131
132 if(ret < 0) {
133 printk("misc_register failed\n");
134 goto err_misc_register;
135 }
136
137 return 0;
138 err_misc_register:
139 return ret;
140
141 }
142
143 //卸载
144 static void test_exit(void)
145 {
146 printk("%s:%s:%d init\n", __FILE__, __FUNCTION__, __LINE__);
147
148
149 //注销misc
150 misc_deregister(&ldm.dev);
151 //释放映射的虚拟地址
152
153 }
154
155 module_init(test_init);
156 module_exit(test_exit);
157
158
159 MODULE_LICENSE("GPL"); //加入GPL许可
