简单字符驱动模板

#include <linux/init.h>
#include <linux/module.h>

#include <linux/types.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>


dev_t devid;
static struct cdev *xx_cdev;
static int xx_major = 0;
static int xx_minor = 0;
static struct class *xx_class;


static int xx_open(struct inode *inode, struct file *file)
{
        printk("xx_open called!\n");

        return 0;
}

static int xx_release(struct inode *inode, struct file *file)
{
        printk("xx_release called!\n");

        return 0;
}


static struct file_operations xx_ops = {
        .owner = THIS_MODULE,
        .open = xx_open,
        .release= xx_release,
};


static int __init xx_init(void)
{
        int err;

        /* init xx_cdev */
        xx_cdev = cdev_alloc();
        cdev_init(xx_cdev, &xx_ops);
        xx_cdev->owner = THIS_MODULE;

        /* get device id */
        alloc_chrdev_region(&devid, 0, 1, "xx_cdev");
        xx_major = MAJOR(devid);
        xx_minor = MINOR(devid);
        printk("xx_major = %d\n", xx_major);
        printk("xx_minor = %d\n", xx_minor);

        /* add xx_cdev */
        err = cdev_add(xx_cdev, devid, 1);
        if (err) {
                printk("Error %d: adding xx_cdev failed!\n", err);
                return -1;
        }

        /* create xx_class 
         * udev will create the device inode with xx_class
         */
        xx_class = class_create(THIS_MODULE, "xx_class");
        if (IS_ERR(xx_class)) {
                printk("Error %d: create xx_class failed!\n", xx_class);
                return -1;
        }
        device_create(xx_class, NULL, devid, NULL, "xx_cdev");

        return 0;
}


static void __exit xx_exit(void)
{
        unregister_chrdev_region(devid, 1);
        cdev_del(xx_cdev);

        device_destroy(xx_class, devid);
        class_destroy(xx_class);
}

module_init(xx_init);
module_exit(xx_exit);

MODULE_LICENSE("GPL");

内核版本：ubuntu 12.04(3.2.0-23-generic)

Makefile参考

# Makefile for kernel module
#
# Author: xxxx
# Email:  xxxx at gmail dot com

# module name
obj_name=cdev

# Comment/uncomment the following line to disable/enable arm_cross_compile
#ARM_CROSS_COMPILE = y

# Comment/uncomment the following line to disable/enable debugging
#DEBUG = y



# Add your debugging flag (or not) to EXTRA_CFLAGS
ifeq ($(DEBUG),y)
 DEBFLAGS = -O -g -DDEBUG # "-O" is needed to expand inlines
else
 DEBFLAGS = -O2
endif

EXTRA_CFLAGS += $(DEBFLAGS)



# call from kernel build system
ifneq ($(KERNELRELEASE),)


obj-m := $(obj_name).o


else


# make modules
ifeq ($(ARM_CROSS_COMPILE), y)
KDIR := 
modules:
	make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=
	chmod 755 *
	
else
KDIR := /lib/modules/$(shell uname -r)/build
modules:
	make -C $(KDIR) M=$(PWD) modules
	chmod 755 *

endif


# make load
load:
	@/sbin/insmod $(obj_name).ko

# make unload
unload:
	@/sbin/rmmod $(obj_name)


# make clean
.PHONY:clean
clean:
	@-rm -rf *.ko *.o *.mod.o *.mod.c *.symvers modul* .*.mod.o.cmd .tmp_versions .Makefile.swp .*.ko.cmd .*.o.cmd

endif