linux驱动之LED驱动_1

步骤：

1、框架

2、完善硬件的操作：

    a.看原理图、引脚

    b.看2440手册

    c.写代码： IO口需要用ioremap映射

我的板子电路如下所示



1、配置GPBCON 寄存器，配置输出   在open函数中去配置

2、配置GPBDAT 寄存器                        在write函数中去配置

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手册资料：

GPBCON 寄存器的物理地址为：0x56000010

GPBDAT  寄存器的物理地址为：0x56000014

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1、首先声明全局变量：

volatile unsigned long *gpbcon = NULL;
volatile unsigned long *gpbdat = NULL;

2、在入口函数中对引脚进行映射

/*映射物理地址*/
gpbcon = (volatile unsigned long *) ioremap(0x56000010,16);
gpbdat = gpbcon + 1;

3、在出口函数中取消映射

iounmap(gpbcon);

4、在open函数中将引脚设置为输出

/*配置 GPB 5 6 7 8为输出*/
*gpbcon &=~((0x3<<(5*2))|(0x3<<(6*2))|(0x3<<(7*2))|(0x3<<(8*2)));//先清零
*gpbcon |=((0x1<<(5*2))|(0x1<<(6*2))|(0x1<<(7*2))|(0x1<<(8*2)));// 配置为1 （输出）

5、在写函数中对用户空间数据进行简单处理

int val;
copy_from_user(&val,buf,count);//从用户空间向内核空间拷贝数据
if(val == 1)
{
//点灯
*gpbdat &=~((1<<5)|(1<<6)|(1<<7)|(1<<8));
}
else
{
//灭灯
*gpbdat|=(1<<5)|(1<<6)|(1<<7)|(1<<8);
}

完整的驱动代码如下：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <asm/io.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <asm/uaccess.h>

static struct class *firstdrv_class;
static struct class_devices *firstdrv_class_dev;

volatile unsigned long *gpbcon = NULL;
volatile unsigned long *gpbdat = NULL;

MODULE_LICENSE("Dual BSD/GPL");
static int first_dev_open(struct inode *inode,struct file *file)
{
/*配置 GPB 5 6 7 8为输出*/
*gpbcon &=~((0x3<<(5*2))|(0x3<<(6*2))|(0x3<<(7*2))|(0x3<<(8*2)));//先清零
*gpbcon |=((0x1<<(5*2))|(0x1<<(6*2))|(0x1<<(7*2))|(0x1<<(8*2)));// 配置为1 （输出）
//printk("first dev open\n");
return 0;
}
static ssize_t first_dev_write(struct file *file,const char __user *buf,size_t count,loff_t *ppos)
{
int val;
copy_from_user(&val,buf,count);//从用户空间向内核空间拷贝数据
if(val == 1)
{
//点灯
*gpbdat &=~((1<<5)|(1<<6)|(1<<7)|(1<<8));
}
else
{
//灭灯
*gpbdat|=(1<<5)|(1<<6)|(1<<7)|(1<<8);
}

//printk("first dev write\n");
return 0;
}
static struct file_operations first_sdv_fops =
{
.owner = THIS_MODULE,
.open  = first_dev_open,
.write = first_dev_write,
};
int major;
int first_drv_init(void)
{

major = register_chrdev(0,"first_drv",&first_sdv_fops);//注册
firstdrv_class = class_create(THIS_MODULE,"first_drv");
if(IS_ERR(firstdrv_class))
return PTR_ERR(firstdrv_class);
firstdrv_class_dev = device_create(firstdrv_class,NULL,MKDEV(major,0),NULL,"wq_device");
if(unlikely(IS_ERR(firstdrv_class_dev)))
return PTR_ERR(firstdrv_class_dev);

/*映射物理地址*/
gpbcon = (volatile unsigned long *) ioremap(0x56000010,16);
gpbdat = gpbcon + 1;
//printk("init   major= %d\n",major);
return 0;
}

void first_dev_exit(void)
{
//printk("exit\n");
unregister_chrdev(major,"first_drv");//卸载

device_unregister(firstdrv_class_dev);
class_destroy(firstdrv_class);
iounmap(gpbcon);
}
module_init(first_drv_init);
module_exit(first_dev_exit);

完整的测试代码如下：

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
/*wq_device on  打开
*wq_device off 关闭
*/
int main(int argc, char **argv)
{
int fd;
int val = 1;
fd = open("/dev/wq_device",	O_RDWR);
if(fd < 0)
{
printf("can't open \n");
}
if(argc != 2)
{
printf("Usage :\n");
printf("%s <on|off>\n",argv[0]);
return 0;
}
if(strcmp(argv[1],"on") == 0)
{
val =1;
}
else
{
val =0;
}
write(fd,&val,4);
return 0;
}