led.c驱动框架2nd

led.c:

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

int major = 249;

void arm_init(void)
{
    /*操作硬件*/
    printk("hello arm init!
");
}

int led_open(struct inode *inode, struct file *file)
{
    arm_init();

    return 0;
}

struct file_operations led_fops = {
    .owner = THIS_MODULE,    //属于本模块所有
    .open = led_open,
};

int led_init(void)
{
    int ret;

    /*模块入口*/
    printk("hello kernel
");
    
    /*注册字符设备驱动*/
    ret = register_chrdev(major,"led-driver",&led_fops);
    if(ret < 0){
        printk("register chrdev led failed
");
        return -EBUSY;
    }

    return 0;
}

void led_exit(void)
{
    /*模块出口*/
    
    /*注销*/
    unregister_chrdev(major,"led-driver");
    printk("bye!
");
}

/*执行insmod 的时候调用module_init*/
module_init(led_init);

/*执行 rmmod 的时侯调用module_exit */
module_exit(led_exit);

MODULE_DESCRIPTION("this my first drivers");
MODULE_AUTHOR("zhang san feng");
MODULE_LICENSE("GPL");    //许可证 (必须)

app.c:

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

int main(int argc,char *argv[])
{
    int fd;        //文件描述符
    
    /*以读的方式打开一个文件,如果文件不存在，则返回错误*/
    fd = open("/dev/led",O_RDONLY);
    if(fd < 0){
        perror("open");
        return -1;
    }
    printf("fd == %d
",fd);

    return 0;
}

Makefile:

obj-m        += led.o

################################################

KERNEL = /home/linux-3.0.8-FS210_v9
ROOTFS = /opt/filesystem
CROSS_COMPILE = arm-cortex_a8-linux-gnueabi-gcc
 
all:
    make M=`pwd` -C $(KERNEL) modules
    $(CROSS_COMPILE) -o app app.c
    cp led.ko /opt/filesystem/test
    cp app /opt/filesystem/test
    cp test.sh /opt/filesystem/test

clean:
    make M=`pwd` -C $(KERNEL) modules clean

install:
    make M=`pwd` -C $(KERNEL) modules_install INSTALL_MOD_PATH=$(ROOTFS)
    

test.sh:

#/bin/bash

insmod led.ko
mknod /dev/led c 249 0
./app