自动创建字符设备，不需mknod

  1 #include<linux/module.h>
  2 #include<linux/kernel.h>
  3 #include<linux/cdev.h>
  4 #include<linux/fs.h>
  5 #include<linux/kdev_t.h>
  6 #include<linux/types.h>
  7 #include<linux/uaccess.h>
  8 #include<linux/string.h>
  9 #include<linux/ioport.h>
 10 #include<asm/io.h>
 11 #include<linux/init.h>
 12 #include<linux/device.h>
 13 #define  GPJ2CON_PA 0xe0200280
 14 #define  GPJ2DAT_PA 0xe0200280
 15 unsigned int *GPJ2CON_VA;
 16 unsigned int *GPJ2DAT_VA;
 17 struct cdev chrdev;
 18 struct resource *res;
 19 struct class *cla;
 20 struct device *dev;
 21 unsigned int TestMajor=0;
 22 unsigned int TestMinor=0;
 23 dev_t dev_no;
 24 int ret;
 25 
 26 int testopen(struct inode *inode,struct file *file)
 27 {
 28     unsigned int a = ioread32(GPJ2CON_VA);
 29     a |= 0x1111;
 30     iowrite32(a,GPJ2CON_VA);
 31     printk("cdev init\n");
 32     return 0;
 33     
 34 }
 35 ssize_t testwrite(struct file *file, const char __user *usr, size_t len, loff_t *off)
 36 {
 37     unsigned int a;
 38     
 39     copy_from_user(&a,usr,len);
 40     iowrite32(a,GPJ2DAT_VA);
 41     
 42 
 43 }
 44 ssize_t testread(struct file *file, char __user *usr, size_t len, loff_t *off)
 45 {
 46     unsigned int a = ioread32(GPJ2DAT_VA);
 47     copy_to_user(usr,&a,len);
 48 
 49 
 50 }
 51 int testrelease(struct inode *inode, struct file *file)
 52 {
 53     printk("close\n");
 54     return 0;
 55 
 56 }
 57 
 58 struct file_operations fops=
 59 {
 60     .owner=THIS_MODULE,
 61     .open = testopen,
 62     .write = testwrite,
 63     .read = testread,
 64     .release = testrelease,
 65 };
 66 static int __init test_init(void)
 67 {
 68     dev_no = MKDEV(TestMajor,TestMinor);
 69     if(dev_no>0)
 70     {
 71         ret = register_chrdev_region(dev_no,1,"chrdev_test");    
 72     }
 73     else
 74     {
 75         alloc_chrdev_region(&dev_no,0,1,"chrdev_test");
 76     }
 77     if(ret<0)
 78     {
 79         return ret;
 80     }
 81     cdev_init(&chrdev,&fops);
 82     chrdev.owner=THIS_MODULE;
 83     cdev_add(&chrdev,dev_no,1);
 84     res = request_mem_region(GPJ2CON_PA,8,"gpj2_led");
 85     GPJ2CON_VA = ioremap(GPJ2CON_PA,8);
 86     GPJ2DAT_VA = GPJ2CON_VA + 1;
 87     cla = class_create(THIS_MODULE,"led_class");
 88     if(cla == NULL)
 89     {
 90         printk("class_creat() error!\n");
 91     }
 92     dev = device_create(cla,NULL,dev_no,NULL,"chrdev_test");
 93     if(dev == NULL)
 94     {
 95         printk("device_creat() error!\n");
 96     }
 97 
 98     return 0;
 99 }
100 
101 static int __exit test_exit(void)
102 {
103     unregister_chrdev_region(dev_no,1);
104     cdev_del(&chrdev);
105     iounmap(GPJ2CON_VA);
106     release_mem_region(GPJ2CON_PA,8);
107     device_destroy(cla,dev_no);
108     class_destroy(cla);
109     return 0;
110 }
111 
112 module_init(test_init);
113 module_exit(test_exit);
114 
115 
116 MODULE_AUTHOR("FENG");
117 MODULE_DESCRIPTION("the first module of char drivers");
118 MODULE_LICENSE("GPL");
119 MODULE_VERSION("V1.0");