linux学习之路_编写ipcore 的linux driver，然后run helloworld

mutougeda · 发表于 2021-3-2 17:40

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引言

我觉得ORPSoC的关键在于‘P’，即programmable。SoC的有优势就在于只要是满足总线inteRFace的ip，可以实现plug & work。

所以一旦完成前面的工作之后，添加属于自己的ip core到ORPSoC的wishbone总线上，并编写它对应的驱动就成为非常关键的一步。

本小节就做一个简单的例子，来说明需要完成的工作步骤及其中遇到的问题和对应的解决方法。

11.1 编写wishbone为interface的ip core（ip_mkg）

1》这一步请参考：

linux学习之路_wishbone实验

2》将其中的my_slave_module链接到ORPSoC的wishbone上。

11.2 编写linux下的driver module

代码及makefile如下：

1》ip_mkg.c

/*
*
* rill mkg driver
*
*/
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <asm/uaccess.h> /* get_user and put_user */
//#include <linux/clk.h>
//#include <linux/ioport.h>
#include <asm/io.h> /*ioremap*/
#include <linux/platform_device.h> /*cleanup_module*/
#include "ip_mkg.h"
void __iomem *g_mkg_mem_base = NULL;
static int device_open(struct inode *inode, struct file *file)
{
g_mkg_mem_base = ioremap(MKG_MEM_BASE,MKG_MEM_LEN);
if(NULL == g_mkg_mem_base)
{
printk(KERN_ERR "mkg open ioremap error!\n");
return -1;
}
else
{
printk("mkg ioremap addr:%d!\n",(int)g_mkg_mem_base);
}
return 0;
}
static int device_release(struct inode *inode, struct file *file)
{
return 0;
}
static ssize_t device_read(struct file *filp, char *buffer, size_t length, loff_t *offset)
{
return 0;
}
static ssize_t device_write(struct file *filp, const char *buffer, size_t count, loff_t *offset)
{
return 0;
}
long device_ioctl(struct file *file, unsigned int ioctl_num, unsigned long ioctl_param)
{
int ret_val = 0;
unsigned int ret = 0;
struct reg_data *new_regs;
switch(ioctl_num)
{
case IOCTL_REG_SET:
{
new_regs = (struct reg_data*)kmalloc(sizeof(struct reg_data), GFP_KERNEL);
if((ret_val = copy_from_user(new_regs, (struct reg_data*)ioctl_param, sizeof(struct reg_data))) != 0)
{
kfree(new_regs);
printk(KERN_ERR " error copy line_datafrom user.\n");
return -1;
}
iowrite16(new_regs->value,g_mkg_mem_base+new_regs->addr);
kfree(new_regs);
}
break;
case IOCTL_REG_GET:
{
new_regs = (struct reg_data*)kmalloc(sizeof(struct reg_data), GFP_KERNEL);
if((ret_val = copy_from_user(new_regs, (struct reg_data*)ioctl_param, sizeof(struct reg_data))) != 0)
{
kfree(new_regs);
printk(KERN_ERR " error copy line_datafrom user.\n");
return -1;
}
ret = ioread16(g_mkg_mem_base+new_regs->addr);
kfree(new_regs);
return ret;
}
break;
}
return -1;
}
struct file_operations our_file_ops = {
.unlocked_ioctl = device_ioctl,
.read = device_read,
.write = device_write,
.open = device_open,
.release = device_release,
.owner = THIS_MODULE,
};
int init_module()
{
int ret_val;
int ret;
void __iomem *ret_from_request;
//=== Allocate character device
ret_val = register_chrdev(MAJOR_NUM, DEVICE_NAME, &our_file_ops);
if (ret_val < 0)
{
printk(KERN_ALERT " device %s failed(%d)\n", DEVICE_NAME, ret_val);
return ret_val;
}
ret = check_mem_region(MKG_MEM_BASE, MKG_MEM_LEN);
if (ret < 0)
{
printk(KERN_ERR "mkg check_mem_region bussy error!\n");
return -1;
}
ret_from_request = request_mem_region(MKG_MEM_BASE, MKG_MEM_LEN, "ip_mkg");
//===ioremap mkg registers
g_mkg_mem_base = ioremap(MKG_MEM_BASE,MKG_MEM_LEN);
if(NULL == g_mkg_mem_base)
{
printk(KERN_ERR "mkg ioremap error!\n");
return -1;
}
else
{
;//printk("mkg ioremap addr:%d!\n",g_mkg_mem_base);
}
printk("mkg module init done!\n");
return 0;
}
void cleanup_module()
{
release_mem_region(MKG_MEM_BASE, MKG_MEM_LEN);
unregister_chrdev(MAJOR_NUM, DEVICE_NAME);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rill zhen:rillzhen@gmail.com");
6 A' i2 T1 r& |) G' k6 |1 m$ V* I

2》ip_mkg.h，需要注意的是ip core的基地址是在写verilog HDL时指定的。

#ifndef __IP_MKG_H__
#define __IP_MKG_H__
#define MAJOR_NUM 102
#define DEVICE_NAME "ip_mkg"
#define MKG_MEM_BASE 0x10000001
#define MKG_MEM_LEN 32
#define IOCTL_REG_SET 0
#define IOCTL_REG_GET 1
struct reg_data
{
unsigned short addr;
int value;
};
#endif
% G. A% q* `2 o& W& J" q9 y) V6 O/ x

3》Makefile

# To build modules outside of the kernel tree, we run "make"
# in the kernel source tree; the Makefile these then includes this
# Makefile once again.
# This conditional selects whether we are being included from the
# kernel Makefile or not.
ifeq ($(KERNELRELEASE),)
# Assume the source tree is where the running kernel was built
# You should set KERNELDIR in the environment if it's elsewhere
KERNELDIR ?= /home/openrisc/soc-design/linux
# The current directory is passed to sub-makes as argument
PWD := $(shell pwd)
modules:
make -C $(KERNELDIR) M=$(PWD) modules ARCH=openrisc CROSS_COMPILE=or32-linux-
modules_install:
make -C $(KERNELDIR) M=$(PWD) modules_install ARCH=openrisc CROSS_COMPILE=or32-linux-
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions *.order *.symvers
.PHONY: modules modules_install clean
else
# called from kernel build system: just declare what our modules are
obj-m := ip_mkg.o
endif j; }1 O2 z; u

11.3 遇到的问题

1》当在执行make时会遇到如下警告：__ioremap undefined。

2》在板子上insmod时会遇到如下error：unknown symbol __ioremap。

11.4 解决方法

在arch/openrisc/mm/ioremap.c中添加如下代码：并重新编译kernel。

#include <linux/module.h>
EXPORT_SYMBOL(__ioremap);6 C# W0 R, I* ?+ g$ E! F+ o( Y

11.5 小结

实验步骤

0》virtualbox虚拟机unbuntu上安装nfs服务

0.0>确保virtualbox能上网

0.1> apt-get install nfs-kernel-server

0.2>创建nfs共享目录：mkdir /home/openrisc/nfs

0.3>vim /etc/exports，添加如下内容

/home/openrisc/nfs *(rw,sync)

0.4>重启nfs服务

sudo /etc/init.d/nfs-kernel-server restart

1》修改arch/openrisc/mm/ioremap.c

2》cd /home/openrisc/soc-design/linux

3》make ARCH=openrisc defconfig;make生成vmlinux

4》cd 到ip_mkg下，make生成ip_mkg.ko模块文件

5》在FPGA板子上运行linux(刚刚生成的vmlinux文件)

6》配置virtualbox的ip

sudo ifconfig eth8 192.168.1.101 broadcast 192.168.1.255

7》配置PC机的ip为192.168.1.102

8》板子起来后默认的ip为192.168.1.100，如果不是，则需要配置为同一网段。确保板子能ping通virtualbox。别忘了将板子和PC用网线连起来。

9》板子上执行mkdir nfs，创建本地nfs共享目录

10》挂载NFS：mount -t nfs -o nolock 192.168.1.101:/home/openrisc/nfs /nfs

11》在virtualbox里将ip_mkg.ko copy到nfs共享目录

12》板子上cd nfs

13》执行insmod ip_mkg.ko加载模块，可以通过lsmod检查一下

14》创建设备节点：mknod /dev/ip_mkg c 102 0

15》测试：cat /dev/ip_mkg，看到如下结果：

16》上面的命令确实有些多，如果不想在每次板子起来后手动敲键盘，可以修改一下rootfs的启动脚本文件，这样就不用每次手动输入了，文件路径如下

soc-design/linux/arch/openrisc/support/initramfs/etc/init.d/rcS

\soc-design\linux\arch\openrisc\support\initramfs\这个目录就是用busybox制作的rootfs的源。

16》运行helloworld

16.1>编写hello.c

#include <stdio.h>
void main()
{
printf("rill helloworld!\n");
}( Y+ L7 F/ v; B, v

16.2>编译： or2-linux-gcc hello.c -o hello

16.3>copy到板子上：cp hello /home/openrisc/nfs

16.4>在板子上cd到/nfs，然后ls可以看到刚copy来的hello文件，最后运行：./hello，可以看到输出：

zawq · 发表于 2021-3-2 18:11

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