new linux device driver

1. Hello world 

2. printk

3. module parameter

4. container_of

5. linked list

6. wait queue

7. timer

8. delay sleep

9. tasklet

10. work queue -1

11. work queue -2

12. call user space program

13. __dev_get_by_name

14. patchwork
     https://lore.kernel.org/patchwork/project/lkml/list/
     https://lkml.org/

15. linux coding style