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);
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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
struct device *device_create(struct class *class, struct device *parent,
dev_t devt, void *drvdata, const char *fmt, ...)
2.6内核驱动要用以下代码移除设备文件：
void device_destroy(struct class *class, dev_t devt)
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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
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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 );
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2.6驱动总体编写框架：
static int __init my_init(void)
{
//分配设备编号
if(主设备号)
{
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
struct device *device_create(struct class *class, struct device *parent,
dev_t devt, void *drvdata, const char *fmt, ...);
}
static int __exit my_exit(void)
{
//移除设备文件
void device_destroy(struct class *class, dev_t devt);
//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 );
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devfs_mk_cdev() and devfs_register() is too old for linux 2.6 ,so we replace them with device_create()
