x86架构下linux驱动编程 看什么书?
发布网友
发布时间：2022-04-22 20:27
共1个回答
热心网友
时间：2022-05-05 06:22
一: 1>建立以.c为后缀的c语言程序文件(里面包含了设备名及设备号等)
2>建立Makefile文件(作用是通过make来产生设备文件*.ko文件,里面可以建立自己的平台所需的设备文件如:arm等).make产生相应的设备文件
二: 要在/dev下建立相应的设备结点(设备名),用insomd *.ko命令将相应的驱动设备文件挂载到内核中.
三:编写测试文件(.c文件)用来测试内核是否已近成功挂载到内核.(编写好相应的测试文件后,用gcc –o Filename Filename.c(测试文件名)来产生相应的可执行文件).
四:如果设备驱动挂载成功,当执行测试文件(./Filename)时会产生相应的结果.
五:可能用到的相关命令:
1.lsmod:列出内核已经载入模块的专题.
输出:
Mole(模块名)size(大小)used by (被..使用)
2.demop:分析可加载模块的依赖性,生成moles.dep文件和映射文件
3.uname –r 显示内核版本(在编写Makefile时使用到)
4.modprobe : linux内核添加和删除模块(相关参数请查看man帮助文档)
5.modinfo:显示内核模块的信息.
6.insmod: 向linux内核中加载一个模块,用法:insmod[filename] [mole options…]
7.rmmod: 删除内核中的模块, 用法: rmmod [-f,w,s,v][molename]
8.dmesg: 显示内核缓冲区,内核的各种信息,内核启动时的信息会写入到/var/log/下.
六.例子1:
第一步：增加头文件和宏定义
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/mole>
#include <linux/kernel>
第二步：添加与字符设备定义及注册有关的数据成员
//定义设备名称
#define DEVICE_NAME "test" //设备名
#define BUF_SIZE 1024
static char tmpbuf[BUF_SIZE];
//定义主次设备号
static unsigned int TestMajor=0; //主
static unsigned int TestMinor=0; //次
static struct cdev *test_cdev;
static dev_t dev;
第三步：增加open/release函数
static int test_chardev_open(struct inode *inode,struct file *file)
{
printk("open major=%d, minor=%d\n", imajor(inode),
iminor(inode));
return 0;
}
static int test_chardev_release(struct inode *inode,struct file *file)
{
printk("close major=%d,minor=%d\n",imajor(inode),
iminor(inode));
return 0;
}
第四步：增加read函数
static ssize_t test_chardev_read(struct file *file,char __user *buf,
size_t const count,loff_t *offset)
{
if(count < BUF_SIZE)
{
if(copy_to_user(buf,tmpbuf,count))
{
printk("copy to user fail \n");
return -EFAULT;
}
}else{
printk("read size must be less than %d\n", BUF_SIZE);
return -EINVAL;
}
*offset += count;
return count;
}
第五步：增加write函数
static ssize_t test_chardev_write(struct file *file, const char __user*buf,size_t const count,loff_t *offset)
{
if(count < BUF_SIZE)
{
if(copy_from_user(tmpbuf,buf,count))
{
printk("copy from user fail \n");
return -EFAULT;
}
}else{
printk("size must be less than %d\n", BUF_SIZE);
return -EINVAL;
}
*offset += count;
return count;
}
第六步：添加增加file_operations成员
static struct file_operations chardev_fops={
.owner = THIS_MODULE,
.read = test_chardev_read,
.write = test_chardev_write,
.open = test_chardev_open,
.release = test_chardev_release,
};
第七步：在模块的入口添加设备的设备号获取及设备注册
static int __init chrdev_init(void)
{
int result;
if(TestMajor)
{
dev=MKDEV(TestMajor,TestMinor);//创建设备编号
result=register_chrdev_region(dev,1,DEVICE_NAME);
} else {
result=alloc_chrdev_region(&dev,TestMinor,1,DEVICE_NAME);
TestMajor=MAJOR(dev);
}
if(result<0)
{
printk(KERN_WARNING"LED: cannot get major %d \n",TestMajor);
return result;
}
test_cdev=cdev_alloc();
cdev_init(test_cdev,&chardev_fops);
//test_cdev->ops=&chardev_fops;
test_cdev->owner=THIS_MODULE;
result=cdev_add(test_cdev,dev,1);
if(result)
printk("<1>Error %d while register led device!\n",result);
return 0;
}
第八步：在模块的出口函数增加设备设备号释放及设备注销函数
unregister_chrdev_region(MKDEV(TestMajor,TestMinor),1);
cdev_del(test_cdev);
第九步：编译并加载该模块
第十步：根据设备号的设置，在文件系统中建立对应的设备节点
#mknod /dev/test c XXX XX
例子2:
驱动文件:
#include <linux/init.h>
#include <linux/mole.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/uaccess.h>
#define DEVICENAME "ccccc"
unsigned int major=221;
unsigned int minor=0;
struct cdev *abc;
dev_t dev;
static char bufrh[1024]="read success!";
static int aaaaa_open(struct inode *inodep, struct file *filep)
{
printk("read success!\n");
return 0;
}
int aaaaa_release(struct inode *inodep, struct file *filep)
{
return 0;
}
static ssize_t aaaaa_read (struct file *filep, char __user *buf, size_tcount, loff_t *offset)
{
if(copy_to_user(buf, bufrh, 1))
{
printk("copy_to_user fail!\n");
}
return 0;
}
ssize_t aaaaa_write (struct file *filep, const char __user *buf,size_t count, loff_t *offse)
{
printk("write!\n");
return 0;
}
static const struct file_operations fops = {
.owner = THIS_MODULE,
.open = aaaaa_open,
.release = aaaaa_release,
.read = aaaaa_read,
.write = aaaaa_write,
};
static int __init aaaaa_init(void)
{
int a;
dev=MKDEV(major, minor);
a=register_chrdev_region(dev, 1, DEVICENAME);
abc=cdev_alloc();
abc->owner=THIS_MODULE;
cdev_init(abc, &fops);
cdev_add(abc, dev, 1);
return 0;
}
static void __exit aaaaa_cleanup(void)
{
cdev_del(abc);
unregister_chrdev_region(dev, 1);
}
mole_init(aaaaa_init);
mole_exit(aaaaa_cleanup);
MODULE_LICENSE("GPL ");
Makefile文件:
obj-m += firstqd.o(相应设备文件名)
KERDIR = /usr/src/linux-headers-2.6.32-24-generic
#KERDIR=/home/linux2.6/linux #arm骞冲彴
PWD=$(shell pwd)
moles:
$(MAKE) -C $(KERDIR) M=$(PWD)moles
pc:
gcc -o fristqd firstqd.c
arm:
arm-linux-gcc -o fristqd firstqd.c
clean:
rm -rf *.o *~core *.depend *.cmd *.ko *.mod.c *.tmp_versions
测试文件(test.c):
#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
char buf[1024];
char bufw[1024]="write success";
int main()
{
int fd,m,n;
fd=open("/dev/aaa",O_RDWR);
if (fd)
{
m=read(fd,buf,100);
printf("read kernel:%s\n",buf);
n=write(fd,bufw,10);
}
//printf("ni hao");
return 0;
}
