Linux字符设备-内核态数据与用户态数据互传

  1 #include <linux/module.h>
  2 #include <linux/init.h>
  3 #include <linux/io.h>
  4 #include <linux/fs.h>
  5 #include <asm/device.h>  //下面这三个头文件是由于动态创建需要加的
  6 #include <linux/device.h>
  7 #include <linux/cdev.h>
  8 #include "my_cdev.h"
  9 #include <asm/uaccess.h>
 10 
 11 
 12 struct cdev cdev;
 13 dev_t devno;//这里是动态分配设备号和动态创建设备结点需要用到的
 14 struct class *cdev_class;
 15 int param;
 16 int my_cdev_open(struct inode *node,struct file *filp)
 17 {
 18     printk("my_cdev_open sucess!\n");
 19     return 0;
 20 }
 21 
 22 long my_cdev_ioctl(struct file *filp ,unsigned int cmd ,unsigned long arg)
 23 {
 24     int rc = -1;
 25 
 26     switch(cmd)
 27     {
 28         case LED_ON:
 29             rc = copy_from_user(&param, (int __user*)arg, 4);
 30             if (0 != rc)
 31             {
 32                 printk("copy_from_user failed.\n");
 33                 break;
 34             }
 35             printk("Param is %d.\n",param);
 36             printk("CMD test: LED_ON is set!\n");
 37             return 0;
 38         case LED_OFF:
 39             printk("CMD test: LED_OFF is set!\n");
 40             param = 1000;
 41             rc = copy_to_user((int __user*)arg,&param,4);
 42             if (0 != rc)
 43             {
 44                 printk("copy_to_user failed.\n");
 45             }
 46             param = 0;
 47             return 0;
 48         default :
 49             return -EINVAL;
 50     }
 51 }
 52 
 53 struct file_operations my_cdev_fops=
 54 {
 55     .open = my_cdev_open,
 56     .unlocked_ioctl = my_cdev_ioctl,
 57 
 58 };
 59 
 60 static int my_cdev_init(void)
 61 {
 62     int ret;
 63     /**动态分配设备号*/
 64     ret = alloc_chrdev_region(&devno,0,1,"my_chardev");
 65     if(ret)
 66     {
 67         printk("alloc_chrdev_region fail!\n");
 68         unregister_chrdev_region(devno,1);
 69         return ret;
 70     }
 71     else
 72     {
 73         printk("alloc_chrdev_region sucess!\n");
 74     }
 75     /**描述结构初始化*/
 76     cdev_init(&cdev,&my_cdev_fops);
 77     /**描述结构注册*/
 78     ret = cdev_add(&cdev,devno,1);
 79     if(ret)
 80     {
 81         printk("cdev add fail.\n");
 82         unregister_chrdev_region(devno,1);
 83         return ret;
 84     }
 85     else
 86     {
 87         printk("cdev add sucess!\n");
 88     }
 89 
 90     cdev_class = class_create(THIS_MODULE,"my_chardev");
 91     if(IS_ERR(cdev_class))
 92     {
 93         printk("Create class fail!\n");
 94         unregister_chrdev_region(devno,1);
 95         return -1;
 96     }
 97     else
 98     {
 99         printk("Create class sucess!\n");
100     }
101 
102     device_create(cdev_class,NULL,devno,0,"my_chardev");
103     
104     return 0;
105 }
106 static void my_cdev_exit(void)
107 {
108     device_destroy(cdev_class,devno);
109     class_destroy(cdev_class);
110     cdev_del(&cdev);
111     unregister_chrdev_region(devno,1);
112     printk("my_cdev_exit sucess!\n");
113 }
114 module_init(my_cdev_init);
115 module_exit(my_cdev_exit);
116 MODULE_LICENSE("GPL");
117 MODULE_AUTHOR("YEFEI");
118 MODULE_DESCRIPTION("YEFEI Driver");

1 #ifndef __MY_CDEV_H__
2 #define __MY_CDEV_H__
3 
4 #define LED_MAGIC ‘L‘
5 #define LED_ON _IOW(LED_MAGIC,0,int)
6 #define LED_OFF _IOR(LED_MAGIC,1,int *)
7 
8 #endif

 1 #include <sys/stat.h>
 2 #include <sys/types.h>
 3 #include <sys/ioctl.h>
 4 #include <fcntl.h>
 5 #include <stdio.h>
 6 #include "my_cdev.h"
 7 
 8 int main(int argc,char *argv[])
 9 {
10     int fd;
11     int cmd;
12     long ret = 0;
13     unsigned long param = 0;
14     if(argc < 2)
15     {
16         printf("Please enter secend param!\n");
17         return 0;
18     }
19     cmd = atoi(argv[1]);
20     fd = open("/dev/my_chardev",O_RDWR);
21     if(fd < 0)
22     {
23         printf("Open dev/my_chardev fail!\n");
24         close(fd);
25         return 0;
26     }
27     switch(cmd)
28     {
29         case 1:
30             param = 500;
31             ret = ioctl(fd,LED_ON,&param);
32             break;
33         case 2:
34             ret = ioctl(fd,LED_OFF,&param);
35             printf("ret is %d. read data is %d.\n",ret,param);
36             break;
37         default:
38             break;
39     }
40     close(fd);
41     return 0;
42 }

1 obj-m := my_char_dev.o
2 KDIR := /home/win/dn377org/trunk/bcm7252/linux/
3 all:
4     make -C $(KDIR) M=$(PWD) modules CROSS_COMPILE=arm-linux- ARCH=arm
5 clean:
6     rm -f *.ko *.o *.mod.o *.mod.c *.symvers *.bak *.order