2.4内核注册驱动要用:
int register_chrdev (unsigned int major,
const char *name, struct file_operations
*fops);
2.4内核注销驱动要用:
int unregister_chrdev( unsigned int major,
const char *name );
2.4内核驱动注册完后,要用以下代码创建设备文件
static devfs_handle_t devfs_handle;
devfs_handle = devfs_register( NULL, DEVICE_NAME,
DEVFS_FL_DEFAULT,
BUTTON_MAJOR,&sbc2410_buttons_fops, NULL);
2.4内核驱动要用以下代码移除设备文件:
devfs_unregister( devfs_handle);
-------------------------------------------------------------------------------------------
2.6驱动i注册设备号要用:
(1)如果主设备号事先知道,要用:
int register_chrdev_region( dev_t first,
unsigned int count, char *name );
(2)如果主设备号为0,则要用动态分配:
int alloc_chrdev_region( dev_t *dev, unsigned
int firstminor,unsigned int count, char *name
);
2.6释放设备号要用:
void unregister_chrdev_region( dev_t first,
unsigned int count );
2.6内核字符设备驱动注册要用:
struct cdev *my_cdev = cdev_alloc();
my_cdev->ops = &chr_fops;
void cdev_init( struct cdev *cdev, struct
file_operations *fops);
int cdev_add( struct cdev *dev, dev_t num, unsigned int
count);
2.6内核字符设备驱动移除要用:
void cdev_del( struct cdev *dev
);
2.6内核驱动注册完后,要用以下代码创建设备文件
从linux内核2.6的某个版本之后,devfs不复存在,udev成为devfs的替代。相比devfs,udev有很多优势,在此就不罗嗦了,提醒一点,udev是应用层的东东,不要试图在内核的配置选项里找到它;加入对udev的支持很简单,以作者所写的一个字符设备驱动为例,在驱动初始化的代码里调用class_create为该设备创建一个class,再为每个设备调用
class_device_create创建对应的设备。大致用法如下:
struct class *myclass =
class_create(THIS_MODULE, “my_device_driver”);
class_device_create(myclass, NULL, MKDEV(major_num, 0), NULL,
“my_device”);
这样的module被加载时,udev
daemon就会自动在/dev下创建my_device设备文件。
class_create()
-------------------------------------------------
linux-2.6.22/include/linux/device.h
struct class *class_create(struct module
*owner, const char *name)
class_create
- create a struct class structure
@owner:
pointer to the module that is to "own" this struct class
@name:
pointer to a string for the name of this class.
在/sys/class/下创建类目录
class_device_create()
-------------------------------------------------
linux-2.6.22/include/linux/device.h
struct class_device *class_device_create(struct
class
*cls,
struct class_device *parent,
dev_t
devt,
struct
device
*device,
const
char
*fmt, ...)
class_device_create - creates a class device and registers it with
sysfs
@cls:
pointer to the struct class that this device should be registered
to.
@parent:
pointer to the parent struct class_device of this new device, if
any.
@devt: the
dev_t for the char device to be added.
@device: a
pointer to a struct device that is assiociated with this class
device.
@fmt: string
for the class device's name
以上也可以用命令创建设备文件:
mknod
/dev/设备文件名字符设备(c是字符设备,b是块设备)
主设备号次设备号
例如:mknod /dev/testChar c 100 0
删除设备入口:
rm /dev/testChar
-------------------------------------------------------------------------------------------------- 2.4驱动总体编写框架:
static int __init my_init(void)
{
//注册设备驱动
register_chrdev (unsigned int
major, const char *name, struct file_operations *fops);
//创建设备文件
static devfs_handle_t
devfs_handle;
devfs_handle = devfs_register( NULL, DEVICE_NAME,
DEVFS_FL_DEFAULT,
BUTTON_MAJOR,&sbc2410_buttons_fops,
NULL);
}
static int __exit my_exit(void)
{
//移除设备文件
devfs_unregister(
devfs_handle);
//注销设备驱动
unregister_chrdev( unsigned int
major, const char *name );
}
module_init( my_init );
module_exit( my_exit );
--------------------------------------------------------------------------------------------------
2.6驱动总体编写框架:
static int __init my_init(void)
{
static struct class
*sbc2440_leds_class = NULL;
if(主设备号) //分配设备编号
{
sbc2440_leds_dev = MKDEV
(LED_MAJOR, LED_MINOR);
result = register_chrdev_region
(sbc2440_leds_dev, count, DEVICE_NAME);
}
else
{
result = alloc_chrdev_region
(&sbc2440_leds_dev, LED_MINOR, count,
DEVICE_NAME);
LED_MAJOR = MAJOR
(sbc2440_leds_dev);
}
//注册字符设备驱动
sbc2440_leds_cdev = cdev_alloc();
if (sbc2440_leds_cdev != NULL)
{
cdev_init (sbc2440_leds_cdev,
&sbc2440_leds_fops);
sbc2440_leds_cdev->ops
= &sbc2440_leds_fops;
sbc2440_leds_cdev->owner
= THIS_MODULE;
if (cdev_add
(sbc2440_leds_cdev, sbc2440_leds_dev, count) )
printk
(KERN_NOTICE "Someting wrong when adding
sbc2440_leds_cdev!/n");
else
printk
("Success adding sbc2440_leds_cdev!/n");
}
//创建设备文件
sbc2440_leds_class =
class_create(THIS_MODULE, “ sbc2440_leds_class”);
class_device_create(sbc2440_leds_class
,NULL,MKDEV(LED_MAJOR,0),NULL,"DEVICE_NAME");
}
static int __exit my_exit(void)
{
class_destroy(sbc2440_leds_class );
class_device_destroy(sbc2440_leds_class,MKDEV(LED_MAJOR,0));
//注销字符设备
cdev_del (sbc2440_leds_cdev);
//释放设备编号:
unregister_chrdev_region (sbc2440_leds_dev,
count);
}
module_init( my_init );
module_exit( my_exit );
红色部分改了有一些改动,可能也存在以下问题,如果网友发现,欢迎指正。谢谢大家!