注册完设备和驱动之后,就需要注册设备节点
Linux杂项设备出现的意义在于:有很多简单的外围字符设备,它们功能相对简单,一个设备占用一个主设备号对于内核资源来说太浪费。所以对于这些简单的字符设备它们共用一个主设备号,不同的设备使用不同的次设备号。
MISC_DYNAMIC_MINOR 表示由系统分配子设备号
生成helloword.ko文件后,执行 insmod helloworld,就可以在 dev/ 文件夹下看到 hello_device_node 文件,表明成功生成设备节点,执行 rmmod helloword,则节点消失。
helloworld.c
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>
#include <linux/fs.h> #define DRIVER_NAME "hello"
#define NODE_NAME "hello_device_node" MODULE_LICENSE("Dual BSD/GPL"); // required
MODULE_AUTHOR("liuShuiDeng"); static long hello_fs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
printk("cmd is %d, arg is %ld\n", cmd, arg);
return ;
}
static int hello_fs_release(struct inode *inode, struct file *file)
{
printk(KERN_EMERG "hello_fs_release");
return ;
}
static int hello_fs_open(struct inode *inode, struct file *file)
{
printk(KERN_EMERG "hello_fs_open");
return ;
}
static struct file_operations hello_fops = {
.owner = THIS_MODULE,
.open = hello_fs_open,
.release = hello_fs_release,
.unlocked_ioctl = hello_fs_ioctl,
};
static struct miscdevice hello_miscdevice = {
.minor = MISC_DYNAMIC_MINOR,
.name = NODE_NAME,
.fops = &hello_fops,
};
static int hello_probe(struct platform_device *p)
{
printk(KERN_EMERG "\nhello_probe\n");
misc_register(&hello_miscdevice);
return ;
} static int hello_remove(struct platform_device *p)
{
printk(KERN_EMERG "\nhello_remove\n");
misc_deregister(&hello_miscdevice);
return ;
} static void hello_shutdown(struct platform_device *p)
{
printk(KERN_EMERG "\nhello_shutdown\n");
} static int hello_suspend(struct platform_device *p, pm_message_t state)
{
printk(KERN_EMERG "\nhello_suspend\n"); return ;
} static int hello_resume(struct platform_device *p)
{
printk(KERN_EMERG "\nhello_resume\n"); return ;
} static struct platform_driver hello_driver={
.probe = hello_probe,
.remove = hello_remove,
.shutdown = hello_shutdown,
.suspend = hello_suspend,
.resume = hello_resume,
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
},
}; static int hello_init(void) //insmod xxx.ko, execute it
{
printk(KERN_EMERG "\nhello world enter~\n\n");
platform_driver_register(&hello_driver);
return ;
} static void hello_exit(void) //rmmod xxx( note: not xxx.ko ), execute it
{
printk(KERN_EMERG "\nhello world exit~\n\n");
platform_driver_unregister(&hello_driver);
} module_init(hello_init);
module_exit(hello_exit);
Makefile
obj-m += helloworld.o # source file is helloworld.c #kernel root directory
KDIR := /home/god/Desktop/logicalVolume/iTop4412_Kernel_3. # directory of source file and Makefile
PWD ?= $(shell pwd) all:
$(MAKE) -C $(KDIR) M=$(PWD) modules
rm -rf *.o
rm -rf Module.*
rm -rf modules.order
rm -rf *.mod.*
rm -rf .*.cmd
rm -rf .*versions
clean:
make -C $(KDIR) M=$(PWD) clean