[Linux Driver] 리눅스 Kernel Module 드라이버 샘플

Kernel Module 뼈대 소스

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>

#define CALL_DEV_NAME    "calldev"
#define CALL_DEV_MAJOR    240

static int onevalue = 1;
static char *twostring = NULL;

module_param(onevalue,int,0);
module_param(twostring,charp,0);

/**
 * module_param(variable,type,property)
 *
 * type        /    variable
 *
 * short     :    short
 * ushort    :     unsigned short
 * int       :    int
 * uint         :    unsigned int
 * long        :    long
 * ulong     :    unsigned long
 * charp    :    char *
 * bool         :    int
 * invbool  :    int
 * intarray :    int *
 *
 * property : generally using 0. *
 *
 */
//to use the param : insmod test.ko onevalue=0x27 twostring"Oh Oh Oh Oh!"


int call_open(struct inode *inode, struct file *filp)
{
    int num = MINOR(inode->i_rdev);
    printk("call open -> minor : %d\n",num);
    return 0;
}

loff_t call_llseek(struct file *filp, loff_t off, int whence)
{
    printk("call llseek -> off : %08X, whence : %08X\n",off,whence);
    return 0x23;
}

ssize_t call_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
    printk("call read -> buf : %08X, count : %08X \n",buf,count);
    return 0x33;
}

ssize_t call_write(struct file *filp, const char *buf, size_t count, loff_t *f_pos)
{
    printk("call write -> buf : %08X, count : %08X \n", buf, count);
    return 0x43;
}

int call_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
    printk("call ioctl -> cmd : %08X, arg : %08X \n",cmd,arg);
    return 0x53;
}

int call_release(struct inode *inode, struct file *filp)
{
    printk("call release\n");
    return 0;
}


struct file_operations call_fops =
{
    .owner    = THIS_MODULE,
    .llseek    = call_llseek,
    .read    = call_read,
    .write    = call_write,
    .ioctl    = call_ioctl,
    .open    = call_open,
    .release= call_release,
};


static int call_init(void)
{
    printk("Hello ,world onevalue:%d twostring=%s\n",onevalue,twostring);

    int result = -1;
    result = register_chrdev(CALL_DEV_MAJOR,CALL_DEV_NAME,&call_fops);

    if(result < 0) return result;

    return 0;
}

static void call_exit(void)
{
    printk("BYe Bye\n");
    unregister_chrdev(CALL_DEV_MAJOR, CALL_DEV_NAME);
}

module_init(call_init);
module_exit(call_exit);

MODULE_AUTHOR("pe.kr.roter");
MODULE_DESCRIPTION("Standard Module Example");
MODULE_LICENSE("Dual BSD/GPL");

Makefile

obj-m    := call_dev.o

KDIR    := /lib/modules/$(shell uname -r)/build
PWD        := $(shell pwd)

default:
    $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules

clean:
    rm -rf *.ko
    rm -rf *.mod.*
    rm -rf .*.cmd
    rm -rf *.o
    rm -rf Module.markers
    rm -rf modules.order
    rm -rf Module.symvers

예제 app 소스

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>

#define DEVICE_FILENAME "/dev/calldev"

int main()
{
    int dev;
    char buff[128];
    int ret;

    printf("1) device file open\n");

    dev = open(DEVICE_FILENAME, O_RDWR|O_NDELAY);
    if(dev >= 0)
    {
        printf("2) seek function call\n");
        ret = lseek(dev, 0x20, SEEK_SET);
        printf("ret = %08X\n",ret);

        printf("3) read function call\n");
        ret = read(dev, 0x30, 0x31);
        printf("ret = %08X\n",ret);

        printf("4) write function call\n");
        ret = write(dev, 0x40, 0x41);
        printf("ret = %08X\n", ret);

        printf("5) ioctl function call\n");
        ret = ioctl(dev, 0x51, 0x52);
        printf("ret = %08X\n",ret);

        printf("6) device file close\n");
        ret = close(dev);
        printf("ret = %08X\n",ret);
    }
    else
    {
        printf("Device open failed\n");
    }

    return 0;
}

실행

#su
#mknod /dev/calldev c 240 32
#insmod call_dev.ko
#rmmod calldev