udev创建linux设备节点

917阅读　0评论2011-11-17　dingzerong
分类：嵌入式

  1. === udev
  2. 在设备被发现时自动加载对应驱动模块。(热插拔，设备被发现时，自动创建dev文件，并加载驱动模块)
  3. 1.    vim /udev/Makefile    修改 安装路径和编译器
  4.     prefix = /nfsroot/
  5.     CROSS_COMPILE = /usr/local/arm/3.4.1/bin/arm-linux-
  6.     
  7.     make
  8.     make install

  10. 2.    vim /nfsroot/etc/init.d/rcS 加上
  11.     mount -t tmpfs tmpfs /dev
  12.     /sbin/udevd -d
  13.     /sbin/udevstart
  14.     开机自动挂载

  16.     ------------------ src -------------------------
  17.     init:
  18.         struct cdev my_cdev;
  19.         struct class *my_class;
  20.         #define DUMMY_MAJOR 255
  21.         #define DUMMY_MINOR 0

  23.         dev_t devno = MKDEV(DUMMY_MAJOR, DUMMY_MINOR);

  25.         cdev_init(&my_cdev, &f_ops);
  26.         cdev_add(&my_cdev, MKDEV(DUMMY_MAJOR, DUMMY_MINOR), 1);

  28.         my_class =class_create(THIS_MODULE, "my_class");
  29.         class_device_create(my_class, MKDEV(DUMMY_MAJOR, DUMMY_MINOR), NULL,"my_dev");

  31.     exit:
  32.         cdev_del(&my_cdev);
  33.         class_device_destroy(my_class, MKDEV(DUMMY_MAJOR, DUMMY_MINOR));
  34.         class_destroy(my_class);
  1. #include <stdio.h>

  3. #include <sys/types.h>
  4. #include <sys/stat.h>
  5. #include <fcntl.h>

  7. int main(void)
  8. {
  9.     int fd;
  10.     fd = open("/dev/test_udev", O_RDWR);
  11.     if(fd < 0)
  12.     {
  13.         printf("open failed\n");
  14.     }

  16.     return 0;
  17. }
  1. #include <linux/module.h>
  2. #include <linux/init.h>

  4. #include <linux/fs.h>
  5. #include <linux/cdev.h>

  7. #include <linux/device.h>

  9. dev_t devno;
  10. struct cdev my_cdev;
  11. struct class *my_class;

  13. int my_open(struct inode *nod, struct file *filp)
  14. {
  15.     printk(" my_open\n");
  16.     return 0;
  17. }
  18. struct file_operations my_ops = {
  19.     .open = my_open,
  20. };

  22. int init_test(void)
  23. {

  25.     devno = MKDEV(253, 0);
  26.     register_chrdev_region(devno, 1, "test udev");
  27.     cdev_init(&my_cdev, &my_ops);

  29.     //init
  30.     my_class = class_create(THIS_MODULE, "test_udev_class");
  31.     device_create(my_class, NULL, devno, NULL, "%s", "test_udev");

  33.     cdev_add(&my_cdev, devno, 1);
  34.     printk("hello udev\n");        
  35.     return 0;
  36. }

  38. void exit_test(void)
  39. {
  40.     cdev_del(&my_cdev);
  41.     device_destroy(my_class, devno);
  42.     class_destroy(my_class);
  43.     unregister_chrdev_region(devno, 1);
  44.     printk("bye\n");        
  45. }

  47. module_init(init_test);
  48. module_exit(exit_test);

  50. MODULE_LICENSE("GPL");

  52. MODULE_AUTHOR("Richard");
  53. MODULE_DESCRIPTION("this is first module");
  54. MODULE_VERSION("v0.1");
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