1 #include <linux/miscdevice.h>
 2 #include <linux/delay.h>
 3 #include <linux/kernel.h>
 4 #include <linux/module.h>
 5 #include <linux/init.h>
 6 #include <linux/mm.h>
 7 #include <linux/fs.h>
 8 #include <linux/types.h>
 9 #include <linux/delay.h>
10 #include <linux/moduleparam.h>
11 #include <linux/slab.h>
12 #include <linux/errno.h>
13 #include <linux/ioctl.h>
14 #include <linux/cdev.h>
15 #include <linux/string.h>
16 #include <linux/list.h>
17 #include <linux/pci.h>
18 #include <linux/gpio.h>
19 
20 
21 #define DEVICE_NAME "mymap"
22 
23 
24 static unsigned char array[10]={0,1,2,3,4,5,6,7,8,9};
25 static unsigned char *buffer;
26 
27 
28 static int my_open(struct inode *inode, struct file *file)
29 {
30     return 0;
31 }
32 
33 
34 static int my_map(struct file *filp, struct vm_area_struct *vma)
35 {    
36     unsigned long page;
37     unsigned char i;
38     unsigned long start = (unsigned long)vma->vm_start;
39     //unsigned long end =  (unsigned long)vma->vm_end;
40     unsigned long size = (unsigned long)(vma->vm_end - vma->vm_start);
41 
42     //得到物理地址
43     page = virt_to_phys(buffer);    
44     //将用户空间的一个vma虚拟内存区映射到以page开始的一段连续物理页面上
45     if(remap_pfn_range(vma,start,page>>PAGE_SHIFT,size,PAGE_SHARED))//第三个参数是页帧号，由物理地址右移PAGE_SHIFT得到
46         return -1;
47 
48     //往该内存写10字节数据
49     for(i=0;i<10;i++)
50         buffer[i] = array[i];
51     
52     return 0;
53 }
54 
55 
56 static struct file_operations dev_fops = {
57     .owner    = THIS_MODULE,
58     .open    = my_open,
59     .mmap   = my_map,
60 };
61 
62 static struct miscdevice misc = {
63     .minor = MISC_DYNAMIC_MINOR,
64     .name = DEVICE_NAME,
65     .fops = &dev_fops,
66 };
67 
68 
69 static int __init dev_init(void)
70 {
71     int ret;    
72 
73     //注册混杂设备
74     ret = misc_register(&misc);
75     //内存分配
76     buffer = (unsigned char *)kmalloc(PAGE_SIZE,GFP_KERNEL);
77     //将该段内存设置为保留
78     SetPageReserved(virt_to_page(buffer));
79 
80     return ret;
81 }
82 
83 
84 static void __exit dev_exit(void)
85 {
86     //注销设备
87     misc_deregister(&misc);
88     //清除保留
89     ClearPageReserved(virt_to_page(buffer));
90     //释放内存
91     kfree(buffer);
92 }
93 
94 
95 module_init(dev_init);
96 module_exit(dev_exit);
97 MODULE_LICENSE("GPL");
98 MODULE_AUTHOR("LKN@SCUT");

 1 #include <unistd.h>
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 #include <string.h>
 5 #include <fcntl.h>
 6 #include <linux/fb.h>
 7 #include <sys/mman.h>
 8 #include <sys/ioctl.h> 
 9 
10 #define PAGE_SIZE 4096
11 
12 
13 int main(int argc , char *argv[])
14 {
15     int fd;
16     int i;
17     unsigned char *p_map;
18     
19     //打开设备
20     fd = open("/dev/mymap",O_RDWR);
21     if(fd < 0)
22     {
23         printf("open fail\n");
24         exit(1);
25     }
26 
27     //内存映射
28     p_map = (unsigned char *)mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, 0);
29     if(p_map == MAP_FAILED)
30     {
31         printf("mmap fail\n");
32         goto here;
33     }
34 
35     //打印映射后的内存中的前10个字节内容
36     for(i=0;i<10;i++)
37         printf("%d\n",p_map[i]);
38     
39 
40 here:
41     munmap(p_map, PAGE_SIZE);
42     return 0;
43 }