tiny4412驱动开发
环境：
操作系统：ubuntu14.04
编译器：arm-linux-gcc-4.4.3
内核：linux-3.5
开发板：tiny4412
1安装编译工具链：
1)网上下载 arm-linux-gcc-4.4.3.tar.gz
2)解压
sudo tar -xvlf arm-linux-gcc-4.4.3.tar.gz
3)新建目录
sudo mkdir /usr/local/arm_4.4.3 arm-linux-gcc-4.4.3.tar.gz
4)移动文件到目录 arm_4.4.3
sudo mv ./opt/FriendlyARM/toolschain/4.4.3/* /usr/local/arm_4.4.3
5)配置环境变量PATH
sudo /etc/bash.bashrc
在这个文件后添加：
export PATH=$PATH:/usr/local/arm_4.4.3/bin export PATH source /etc/bash.bashrc
6)配置32bit的库
sudo apt-get install libc6:i386 sudo apt-get install lib32ncurses5 sudo apt-get install lib32z1 sudo apt-get install libstdc++6 sudo apt-get install lib32stdc++6
7)最后检查是否安装成功
arm-linux-gcc -v
2将linux-3.5文件夹下tiny4412_linux_defconfig中的内容复制到.config中。
3编译内核
make ARCH=arm CROSS_COMPILE=arm-linux-
编译成功后：
4编写驱动程序和Makefile。
obj-m:=globalmem.o globalmemmodule-objs:=module KDIR:=/home/pc/linux-3.5 MAKE:=make default: $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules clean: $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) clean
Globalmem.c:
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <asm/io.h>
#include <linux/slab.h>
#include <linux/version.h>
#if LINUX_VERSION_CODE > KERNEL_VERSION(3, 3, 0)
#include <asm/switch_to.h>
#else
#include <asm/system.h>
#endif
#include <asm/uaccess.h>
#define GLOBALMEM_SIZE 0x1000 /*全局内存最大 4K 字节*/
#define MEM_CLEAR 0x1 /*清 0 全局内存*/
#define GLOBALMEM_MAJOR 150 /*预设的 globalmem 的主设备号*/
static int globalmem_major = GLOBALMEM_MAJOR;
/*globalmem 设备结构体*/
struct globalmem_dev
{
struct cdev cdev; /*cdev 结构体*/
unsigned char mem[GLOBALMEM_SIZE]; /*全局内存*/
};
struct globalmem_dev *globalmem_devp; /*设备结构体指针*/
int globalmem_open(struct inode *inode, struct file *filp)
{
filp->private_data = globalmem_devp;
return 0;
}
int globalmem_release(struct inode *inode, struct file *filp)
{
return 0;
}
long globalmem_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct globalmem_dev *dev = filp->private_data;
/*
获得设备结构体指针
*/
switch (cmd)
{
case MEM_CLEAR:
memset(dev->mem, 0, GLOBALMEM_SIZE);
printk(KERN_INFO "globalmem is set to zero\n");
break;
default:
return - EINVAL;
}
return 0;
}
static ssize_t globalmem_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalmem_dev *dev = filp->private_data; /*获得设备结构体指针*/
/*分析和获取有效的写长度*/
if (p >= GLOBALMEM_SIZE)
return count ? - ENXIO: 0;
if (count > GLOBALMEM_SIZE - p)
count = GLOBALMEM_SIZE - p;
/*内核空间->用户空间*/
if (copy_to_user(buf, (void*)(dev->mem + p), count))
{
ret = - EFAULT;
}
else
{
*ppos += count;
ret = count;
printk(KERN_INFO "read %d bytes(s) from %d\n", count, p);
}
return ret;
}
static ssize_t globalmem_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalmem_dev *dev = filp->private_data; /*获得设备结构体指针*/
/*分析和获取有效的写长度*/
if (p >= GLOBALMEM_SIZE)
return count ? - ENXIO: 0;
if (count > GLOBALMEM_SIZE - p)
count = GLOBALMEM_SIZE - p;
/*用户空间->内核空间*/
if (copy_from_user(dev->mem + p, buf, count))
ret = - EFAULT;
else
{
*ppos += count;
ret = count;
printk(KERN_INFO "written %d bytes(s) from %d\n", count, p);
}
return ret;
}
static loff_t globalmem_llseek(struct file *filp, loff_t offset, int orig)
{
loff_t ret = 0;
switch (orig)
{
case 0: /*相对文件开始位置偏移*/
if (offset < 0)
{
ret = - EINVAL;
break;
}
if ((unsigned int)offset > GLOBALMEM_SIZE)
{
ret = - EINVAL;
break;
}
filp->f_pos = (unsigned int)offset;
ret = filp->f_pos;
break;
case 1: /*相对文件当前位置偏移*/
if ((filp->f_pos + offset) > GLOBALMEM_SIZE)
{
ret = - EINVAL;
break;
}
if ((filp->f_pos + offset) < 0)
{
ret = - EINVAL;
break;
}
filp->f_pos += offset;
ret = filp->f_pos;
break;
default:
ret = - EINVAL;
break;
}
return ret;
}
static const struct file_operations globalmem_fops =
{
.owner = THIS_MODULE,
.llseek = globalmem_llseek,
.read = globalmem_read,
.write = globalmem_write,
.unlocked_ioctl = globalmem_ioctl,
.open = globalmem_open,
.release = globalmem_release,
};
static void globalmem_setup_cdev(struct globalmem_dev *dev, int index)
{
int err, devno = MKDEV(globalmem_major, index);
cdev_init(&dev->cdev, &globalmem_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &globalmem_fops;
err = cdev_add(&dev->cdev, devno, 1);
if (err)
printk(KERN_NOTICE "Error %d adding LED%d", err, index);
}
int globalmem_init(void)
{
int result;
dev_t devno = MKDEV(globalmem_major, 0);
/* 申请设备号*/
if (globalmem_major)
result = register_chrdev_region(devno, 1, "globalmem");
else /* 动态申请设备号 */
{
result = alloc_chrdev_region(&devno, 0, 1, "globalmem");
globalmem_major = MAJOR(devno);
}
if (result < 0)
return result;
/* 动态申请设备结构体的内存*/
globalmem_devp = kmalloc(sizeof(struct globalmem_dev), GFP_KERNEL);
if (!globalmem_devp) /*申请失败*/
{
result = - ENOMEM;
goto fail_malloc;
}
memset(globalmem_devp, 0, sizeof(struct globalmem_dev));
globalmem_setup_cdev(globalmem_devp, 0);
return 0;
fail_malloc: unregister_chrdev_region(devno, 1);
return result;
}
void globalmem_exit(void)
{
cdev_del(&globalmem_devp->cdev); /*注销 cdev*/
kfree(globalmem_devp); /*释放设备结构体内存*/
unregister_chrdev_region(MKDEV(globalmem_major, 0), 1); /*释放设备号*/
}
MODULE_AUTHOR("Song Baohua");
MODULE_LICENSE("Dual BSD/GPL");
module_param(globalmem_major, int, S_IRUGO);
module_init(globalmem_init);
module_exit(globalmem_exit);
5输入make：
6连接启动板子，将所需文件传送上去。
7输入insmod globalmem.ko命令将字符驱动设备加载进去。
然后输入cat /proc/devices命令查看驱动信息。
8验证
echo "hello world" > /dev/globalmem cat /dev/globalmem
结果输出helloworld。
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