FL2440驱动添加（1）：hello world 驱动模块添加

试试第一个hello world模块添加：

1，在添加drivers/char/hello.c

/*********************************************************************************
 *      Copyright:  (C) 2014 zhouguangfeng<zhouguangfeng91@gmail.com>
 *                  All rights reserved.
 *
 *       Filename:  hello.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(08/09/2014)
 *         Author:  zhouguangfeng <zhouguangfeng91@gmail.com>
 *      ChangeLog:  1, Release initial version on "08/09/2014 06:23:18 PM"
 *                 
 ********************************************************************************/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>

MODULE_LICENSE ("Dual BSD/GPL");

static int __init hello_init (void)
{
    printk (KERN_INFO "Hello world ");
    return 0;
}

static void __exit hello_exit (void)
{
    printk (KERN_INFO "Goodbye world ");
    return;
}

module_init (hello_init);
module_exit (hello_exit);

其中 printk是内核特有的打印函数，类似与printf，只是它不依赖库文件，KERN_INFO为

打印优先级

2，修改drivers/char/Kconfig文件，添加在make menuconfig的选项

#
# Character device configuration
#


menu "Character devices"


source "drivers/tty/Kconfig"


# add  by zhouguangfeng 2014.8.9 for "Hello world" 

config FL_HELLO
    tristate "CCTE2440 Hello Driver"
    depends on ARCH_S3C2440
    help
    FL2440 Hello Module.

3，修改drivers/char/Makefile，编译添加的hello.c

obj-$(CONFIG_FL_HELLO) += hello.o

4,make menuconfig选项

[*] Enable loadable module support  ---> 

[*]   Module unloading   //需要支持，否则已经加载的模块无法卸载载

  Device Drivers  --->

Character devices  --->

<M> FL2440 Hello Driver  //刚才添加的Kconfig选项，这里编译为模块

5，make之后，下载内核与文件系统，挂在hello.ko模块

Copyright (C) 2014 zhouguangfeng<zhouguangfeng@gmail.com>
dm9000 dm9000 eth0: link up, 100Mbps, full-duplex, lpa 0xCDE1
zhouxiaoxing login: root
>: ls
apps     data     etc      info     lib      mnt      root     sys      usr
bin      dev      hello    init     linuxrc  proc     sbin     tmp      var
>: ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: seq=0 ttl=64 time=2.592 ms
64 bytes from 192.168.1.1: seq=1 ttl=64 time=0.685 ms
64 bytes from 192.168.1.1: seq=2 ttl=64 time=0.658 ms

--- 192.168.1.1 ping statistics ---
9 packets transmitted, 9 packets received, 0% packet loss
round-trip min/avg/max = 0.658/0.896/2.592 ms

>: tftp -gr hello.ko 192.168.1.3
hello.ko             100% |*******************************|  2365   0:00:00 ETA
>: ls
apps      dev       hello.ko  lib       proc      sys       var
bin       etc       info      linuxrc   root      tmp
data      hello     init      mnt       sbin      usr

>: insmod hello.ko 

Hello world

>: rmmod hello 

Goodbye world