[系统运维]一般字符驱动框架

driver c文件：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/err.h>

#define MMAP_DEV_NAME "mmapdev"

static dev_t mmap_dev_no = 0;
static struct cdev mmap_dev_cdev;
static struct class *mmap_dev_cls;
static struct device *mmap_device;

static struct file_operations mmapdrv_fops = 
{
	.owner = THIS_MODULE,
};

static int __init mmapdrv_init(void)
{
	int ret = -1;

	printk("mmapdrv init...\n");

	ret = alloc_chrdev_region(&mmap_dev_no,0,1,MMAP_DEV_NAME);//动态注册设备号
	if(ret < 0)
	{
		printk("alloc mmap dev no fail!\n");
		return ret;
	}

	cdev_init(&mmap_dev_cdev,&mmapdrv_fops);
	mmap_dev_cdev.owner = THIS_MODULE;

	ret = cdev_add(&mmap_dev_cdev,mmap_dev_no,1);
	if(ret != 0)
	{
		printk("cdev add faild!\n");
		goto cdev_add_err;
	}
#if 1
	mmap_dev_cls = class_create(THIS_MODULE, MMAP_DEV_NAME);//自动创建设备节点
	if(IS_ERR(mmap_dev_cls))//判断指针是否有错
	{
		printk("class create failed!\n");
		goto cdev_class_err;
	}

	mmap_device = device_create(mmap_dev_cls,NULL,mmap_dev_no,NULL,MMAP_DEV_NAME);
	if(IS_ERR(mmap_device))//判断指针是否有错
	{
		printk("device create failed!\n");
		goto device_create_err;
	}
#endif
	return 0;

device_create_err:
	class_destroy(mmap_dev_cls);
cdev_class_err:
	cdev_del(&mmap_dev_cdev);
cdev_add_err:
	unregister_chrdev_region(mmap_dev_no,1);
	return ret;
}

static void __exit mmapdrv_exit(void)
{
	printk("mmapdrv exit...\n");
	device_destroy(mmap_dev_cls,mmap_dev_no);
	class_destroy(mmap_dev_cls);	
	cdev_del(&mmap_dev_cdev);
	unregister_chrdev_region(mmap_dev_no,1);
}



module_init(mmapdrv_init);
module_exit(mmapdrv_exit);

MODULE_LICENSE("GPL");

Makefile 文件：

obj-m:=mmap_driver.o
PWD:=$(shell pwd)
KERNELDIR:=/lib/modules/$(shell uname -r)/build

all:
	make -C $(KERNELDIR) M=$(PWD) modules
clean:
	@rm -rf *.o *.mod.c *.mod.o *.ko *.order *.symvers .*cmd .tmp_versions *.mod