今天开始我们来学习linux驱动的开发,驱动分为字符设备驱动,块设备,网络设备驱动,讲这个之前我说一下我用的虚拟机版本和linux内核版本,开始我用的redhat 9.0 开始用的好好的,到后来自己编译busybox的时候总是出错误,这个期间我尝试了很多次,在网上也找到了很多方法,可还是解决不了问题,后来找到了原因是虚拟机版本的问题,后来我换了ubuntu9.10,那些错误就没有了。
在这里我我在说明一下fl2440光盘自带的linux2.6.28.7是不是支持自动创建设备节点的,需要在/etc/init.d/rcs中添加 mdev -s 。学习的同时可以参考韦东山老师的视频,讲得非常好,注意下我们的代码和他的代码有一点区别,就是一些函数可能用的不同(是内核版本的问题),以后我讲的驱动都是用的linux2.6.28.7,这样也方便你们学习。
这些代码你直接copy上去都是可以用的废话不多说了,直接上代码:
/s3c2440_leds.c
//#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/device.h>
//#include <linux/devfs_fs_kernel.h>
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/gpio.h>
#define device_name "leds"
#define led_major 231
#define led_off 0
#define led_on 1
#define all_led_off 3
#define all_led_on 4
module_license("dual bsd/gpl");
static struct class *led_2;
static unsigned long led_table [] = {
s3c2410_gpb5,
s3c2410_gpb6,
s3c2410_gpb8,
s3c2410_gpb10,
};
/*等价于设置gpfcon*/
static unsigned int led_cfg_table [] = {
s3c2410_gpb5_outp, //0x01<<10 defined in refg-gpio.h
s3c2410_gpb6_outp,
s3c2410_gpb8_outp,
s3c2410_gpb10_outp,
static int s3c2440_leds_ioctl( struct inode *inode, struct file *file,unsigned int cmd,unsigned long arg)
{
int i;
if (arg > 4)
return -einval;
}
switch(cmd)
case led_on: //set the pin
s3c2410_gpio_setpin(led_table[arg], 0);
break;
case led_off: //clr the pin
s3c2410_gpio_setpin(led_table[arg], 1);
case all_led_on: //set all pin
for (i = 0; i < 4; i++)
s3c2410_gpio_setpin(led_table[i], 0);
case all_led_off: //clr all pin
s3c2410_gpio_setpin(led_table[i], 1);
default:
static struct file_operations s3c2440_leds_fops = {
.owner = this_module,
.ioctl = s3c2440_leds_ioctl,
static int major;
static int __init s3c2440_leds_init(void)
int i;
major = register_chrdev(0, device_name, &s3c2440_leds_fops);
if (major < 0)
printk(device_name " can't register major number\n");
return major;
led_2 = class_create(this_module, device_name);
device_create(led_2, null, mkdev(major, 0), null, "led_2");
for (i = 0; i < 4 ; i++)
s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);
s3c2410_gpio_setpin(led_table[i], 1);
printk(device_name " initialized\n");
return 0;
static void __exit s3c2440_leds_exit(void)
unregister_chrdev(major, device_name);
device_destroy(led_2,mkdev(major, 0));
class_destroy(led_2);
module_init(s3c2440_leds_init);
module_exit(s3c2440_leds_exit);
测试程序:
#include "stdio.h"
#include "unistd.h"
#include "sys/types.h"
#include "sys/ioctl.h"
#include "stdlib.h"
#include "termios.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "sys/time.h"
int main(int argc, char **argv)
unsigned int on;
unsigned int led_num;
int fd;
fd=open("/dev/led_2",o_rdwr);//打开文件返回值是个非负值
if (fd < 0)
printf("open device led");
return -1;
printf("%s <on/off>\n",argv[0]);
if (argc == 2)
sscanf(argv[1], "%d", &on);
if (on < 2)
ioctl(fd, on+3, 0);
else
printf("usage: led led_num 0|1 or led 0|1\n");
exit(1);
if (argc == 3)
sscanf(argv[1], "%d", &led_num);
sscanf(argv[2], "%d", &on);
if ((on < 2) && (led_num>0 || led_num < 4))
ioctl(fd, on, (led_num-1));
close(fd);
在编写个makefile:
obj-m :=test.o
kerneldir ?= /home/work/linux/linux-2.6.28.7//内核路径
pwd := $(shell pwd)
$(make) -c $(kerneldir) m=$(pwd) modules
clean:
rm -f *o *.mod.o *mod.c *.symvers *.order