S3C2440_GPB7的小驱动

已经很久没写过驱动了，今天突然说要控制一个LED灯，闲来无事便自己写了一个，权当复习，闲话少说直接代码......

驱动代码(gpg7.c)：

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

#define GPB_ON  1
#define GPB_OFF 0

static unsigned int oam_major=0;
static struct class *oam_class =NULL;

static volatile unsigned long   *gpfcon;
static volatile unsigned long   *gpfdat;

/*1. 实现对硬件的操作方法*/
static int oam_open(struct inode *inode, struct file *file)
{
    /*初始化硬件*/
    /*将GPB7设置为输出管脚*/
    *gpfcon &= ~(0x3<<14);
    *gpfcon |= (0x1<<14);
    return 0;
}

ssize_t oam_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
    //TODO
    return 0;
}

static ssize_t oam_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
    char val;
    int ret;

    /*获取用户空间传入的值*/
    ret =copy_from_user(&val,buf,1);
    if(!val)
    {
        *gpfdat |= (0x1 << 7);
    }
    else
    {
        *gpfdat &= ~(0x1 << 7);
    }

    return 0;
}

static int oam_ioctl(struct inode *inode, struct file *file, unsigned int cmd,unsigned long arg)
{
    switch(cmd)
    {
        case GPB_OFF:
                *gpfdat |= (0x1 << 7);
                break;
        case GPB_ON:
                *gpfdat &= ~(0x1 << 7);
                break;
        default:break;
    }
    return 0;
}

/*2. 构建file_operations结构体*/
static struct file_operations oam_fops={
    .owner  = THIS_MODULE,
    .open   = oam_open,
    .write  = oam_write,
    .read   = oam_read,
    .ioctl  = oam_ioctl,
};

/*3. 实现入口函数*/
static int __init oam_init(void)
{
    /*1.注册*/
    oam_major =register_chrdev(0,"gpb7",&oam_fops);

    /*2. 构建设备节点*/
    oam_class =class_create(THIS_MODULE,"gpb7_class");
    device_create(oam_class,NULL,MKDEV(oam_major,0),NULL,"gpb7");

    /*3.将物理地址映射为虚拟地址*/
    gpfcon =ioremap(0x56000010,4096);
    gpfdat =gpfcon +1;

    return 0;
}

/*4.实现出口函数*/
static void __exit oam_exit(void )
{
    unregister_chrdev(oam_major,"gpb7");
    class_destroy(oam_class);
    device_destroy(oam_class,MKDEV(oam_major,0));
    iounmap(gpfcon);
}

module_init(oam_init);
module_exit(oam_exit);
MODULE_LICENSE("GPL");

测试代码(gpg7_test.c)：

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>

#define GPB_ON  1
#define GPB_OFF 0

void print_usage(char *str)
{
    printf("please input follow this!\n");
    printf("%s <dev> <on/off> \n",str);
}

int main(int argc, char **argv)
{
    int fd = 0;
    //char buf[1];
    int cmd = 0;
    if(argc!=3&&argc!=2)
    {
        print_usage(argv[0]);
        return -1;
    }
    fd =open(argv[1], O_RDWR);
    if(fd <0)
    {
        printf("cannot open the dev!\n");
        return -1;
    }
    if(strcmp(argv[2],"on")==0)
    {
        cmd=GPB_ON;
    }
    else if(strcmp(argv[2],"off")==0)
    {
        cmd=GPB_OFF;
    }
    //write(fd, buf, 1);
    ioctl(fd,cmd,NULL);
    return 0;
}

Makefile：

all:
    make -C /home/farsight/anyk/s3c2440/kernal/linux-2.6.30.4 M=`pwd` modules
clean:
    make -C /home/farsight/anyk/s3c2440/kernal/linux-2.6.30.4 M=`pwd` clean

obj-m += gpb7.o

相对而言，字符设备还是挺简单的。