Linux驱动开发③--LED流水灯驱动示例

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define DEVICE_NAME	"FLOWLED"


#define LED_MAJOR 246 /* 主设备号*/
#define LED_ON 1
#define LED_OFF 2

struct led_dev
{
    struct cdev cdev;
    unsigned char value;
};
struct led_dev *leddev;

static int flowled_open(struct inode *inode, struct file *filp)
{
	printk("flowled_open\r\n");
	return 0;
}

static int flowled_release(struct inode *inode, struct file *filp)
{
	printk("flowled_release\r\n");
	return 0;
}

static int flowled_write(struct file *file, const char *buffer,size_t count, loff_t *ppos)
{
	// printk("%s",buffer);
	printk("flowled_write:%d\r\n",count);
	return count;
}

static int flowled_read(struct file *file, char *buffer,size_t count, loff_t *ppos)
{
	printk("flowled_read\r\n");
	// *ppos = 0;
	// buffer[0] = 'a';
	// buffer[1] = 'b';
	// buffer[2] = 0;
    return 3;
}

int flowled_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
    return 0;
}

static struct file_operations flowled_fops = 
{
	.owner		=	THIS_MODULE,
	.open		=	flowled_open,
	.read		=	flowled_read,	
	.write		=	flowled_write,	
	.release	=	flowled_release,
	
};

static int __init flowled_init(void)
{
	int result,err;
	
	printk("flowled_init\r\n");
	
    //申请设备号
    dev_t devno = MKDEV(LED_MAJOR, 2);
    if(LED_MAJOR)
        result = register_chrdev_region(devno, 1, DEVICE_NAME);
	
    /*动态申请设备结构体的内存*/
    leddev = kmalloc(sizeof(struct led_dev), GFP_KERNEL);
    if (!leddev)
    {
        result = -ENOMEM;
        goto fail_malloc;
    }
    //硬件初始化,推荐在open中实现
    //sep4020_flowled_setup();
    //字符设备注册
    cdev_init(&(leddev->cdev), &flowled_fops);
    leddev->cdev.owner = THIS_MODULE;
    err = cdev_add(&leddev->cdev, devno, 1);// 创建设备文件
    return 0;
	
fail_malloc:
    unregister_chrdev_region(devno, 1);
    return result;
}

static void __exit flowled_exit(void)
{
    //删除设备文件
    cdev_del(&leddev->cdev);
    kfree(leddev);
    unregister_chrdev(LED_MAJOR, DEVICE_NAME);
	printk("flowled_exit\r\n");
}

module_init(flowled_init); //向Linux系统记录设备初始化的函数名称
module_exit(flowled_exit); //向Linux系统记录设备退出的函数名称

MODULE_LICENSE("GPL");
MODULE_AUTHOR("tangquan");
MODULE_DESCRIPTION("simple char driver!");