自动创建设备节点

static struct class *firstdrv_class;

static struct class_device *firstdrv_dev;

入口：

firstdrv_class = class_creat(THIS_MODULE,"firstdrv");

firstdrv_drv = class_device_creat(firstdrv_class,NULL,MKDEV(mayjor,0),NULL,"xyz");

出口：

class_device_unregister(firstdrv_drv);

class_destroy(firstdrv_class);