OK6410 linux第一个字符型设备驱动：LED驱动

在OK6410开发板上实现linux环境下的第一个字符设备驱动： LED驱动。

下面是驱动代码，内核是linux-3.0.1版本。

        #include 
        #include 
        #include 
        #include 
        #include 
        #include 
        #include /*copy_to_user,copy_from_user*/
        #include 
        #include 
        #include 
        #include 
        #include 
        #include 
        #define LED_MAJOR 0
        volatile unsigned long *GPM_CON = NULL;
        volatile unsigned long *GPM_DAT = NULL;
        static struct class *LED_Class;
        static struct class_device *LED_Class_Devs;
        int led_open (struct inode *inode,struct file *filp) 
        {  
        printk("LED_drv_open\n");
        /* 配置GPM0,1,2,3输出*/
        *GPM_CON &= 0xffff1111;//~((0xf<<(0*4))|(0xf<<(1*4))|(0xf<<(2*4))|(0xf<<(3*4)));
        //*GPM_CON |= ((0x1<<(0*4))|(0x1<<(1*4))|(0x1<<(2*4))|(0x1<<(3*4)));
        return 0;  
        } 
        ssize_t led_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos)  
        {  
            printk("#########read######\n");  
            return count;  
        }  
        ssize_t led_write (struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)  
        {  
            int val;
            printk("LED_drv_write\n");
            copy_from_user(&val,buf,count);
            if(1==val)
            {
                *GPM_DAT &=0x0;  //关灯
            }
            else
            {
                *GPM_DAT |= 0xf;//开灯
            }
            return count;  
        }  
        int led_release (struct inode *inode, struct file *filp)  
        {  
            printk("#########release######\n");  
            return 0;  
        }  
        struct file_operations led_fops ={  
            .owner = THIS_MODULE,  
            .open = led_open,  
            .read = led_read,  
            .write = led_write,  
            .release = led_release,  
        };  
        int major;  
        int __init led_init (void)  
        {  
            int major;  
            printk ("Test led dev\n");  
            major = register_chrdev(0,"led",&led_fops);  //向内核注册驱动
            if (major <0)  
            {  
                printk ("register %s char dev error\n","led");  
                return -1;  
            }  
            LED_Class=class_create(THIS_MODULE,"LED");
            if(IS_ERR(LED_Class))
                return PTR_ERR(LED_Class);
            LED_Class_Devs = device_create(LED_Class,NULL,MKDEV(major,0),NULL,"LED");
            if(unlikely(IS_ERR(LED_Class_Devs)))
                return PTR_ERR(LED_Class_Devs);
                GPM_CON = (volatile unsigned long *)ioremap(0x7F008820,4);
            GPM_DAT=GPM_CON+1;      
            return 0;  
        }  
        void __exit led_exit (void)  
        {  
            unregister_chrdev(major,"led");
        //  device_destroy(LED_Class_Devs);
        /*  class_device_unregister(LED_Class_Devs);*/
            class_destroy(LED_Class);
            iounmap(GPM_CON);
            printk ("module exit\n");  
            return ;  
        }     
        module_init(led_init);  
        module_exit(led_exit);  
        MODULE_AUTHOR("liqiuhua [email protected]");
        MODULE_DESCRIPTION("S3C6410 LED driver");
        MODULE_LICENSE("GPL");
        MODULE_ALIAS("platform:s3c6410_led");

下面是测试代码:

    #include   
    #include   
    #include   
    #include   
    int main (int argc, char **argv)  
    {  
        int fd;  
        char buf[10]={0,1};  
        int val;
        fd = open("/dev/LED",O_RDWR);  
        if (fd < 0)  
        {  
            printf ("Open /dev/LED file error\n");  
            return -1;  
        }     
        if(argc != 2) 
        {
            printf ("Usage: \n");
            printf ("%s \n",argv[0]);
            return -1;
        }
        if(strcmp(argv[1],"on")==0)
            val=1;
        else
            val=0;
        write(fd,&val,4);
        close (fd);  
        return 0;  

    }