doubts :To write a generic device driver for pci device.

**adityapethe** · 01-30-2005

PROJECT :To write a generic device driver for pci device.

SOURCES : pci.c & pci.h files in the linux source files.
/usr/src/linux/drivers/pci/pci.c
/usr/include/linux/pci.h

CURRENT STEP : To link the files My_prog.c and pci.c

PROBLEM_1 : Unable to form pci.o and to solve its dependencies. Trying to write makefile for it.

PROBLEM_2 : What all #define's and #include's to place in My_prog.c.

My_prog.c is written with just one function call from file pci.h.
Just to see if the whole thing compiles. But we are unable to suceed.

Unable to deal with
#define __KERNEL__. and
#include<modules.h>
#include<linux/config.h>
#include<pci.h>

Code:
//******************My_prog.c**********************
#ifndef __KERNEL__
#define __KERNEL__
#endif
#ifndef MODULE
#define MODULE
#endif

#include <linux/config.h>
#include <linux/module.h>

#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/pci.h>

int main()
{
struct pci_dev *dev=NULL;
dev = (struct pci_dev *)pci_find_device( 1 , 1 , dev);
if(!dev)
{
printf("\n\n\t\tNO DEVICE FOUND...!!!");
}
else
{
printf("\n\n\t\tDEVICE FOUND...!!!");
}
return 0;
}

**afrolinux** · 01-30-2005

From www.freeos.com

Device drivers in Linux are known as modules and can be loaded dynamically
into the kernel using the insmod command.

A single module can be compiled alone, and also can be linked to the
kernel (here, care has to be taken on the type of driver).

eg: A simple module

#define MODULE
#include <linux/module.h>

int init_module (void) /* Loads a module in the kernel */
{
printk("Hello kernel n");
return 0;
}

void cleanup_module(void) /* Removes module from kernel */
{
printk("GoodBye Kerneln");
}

Compiling the module

# gcc -c hello.c
# insmod hello.o

The output is

Hello kernel

# rmmod hello.o

GoodBye Kernel

I hope it help,

afrolinux

**kokyi2** · 01-31-2005

I tried ur program in Fedora 3 .I can successfully complie using gcc.
but I got this problem
hello.o (-1 : invalid module format)
I think it may be the problem of insmod.

Anything u wanna suggest to debug..

**afrolinux** · 01-31-2005

Put in Makefile the following entry

Code:

obj-m += hello.o

and compile with :

Code:

$make -C /usr/src/linux-`uname -r` SUBDIRS=$PWD modules

Insert the module with is (extension '.ko' for 2.6.x kernels and '.o' for formers):

Code:

insmod ./hello.ko

For removing

Code:

rmmod hello

afrolinux

**afrolinux** · 01-31-2005

Code:

TARGET  &#58;= hello-1
WARN    &#58;= -W -Wall -Wstrict-prototypes -Wmissing-prototypes
INCLUDE &#58;= -isystem /lib/modules/`uname -r`/build/include
CFLAGS  &#58;= -O2 -DMODULE -D__KERNEL__ $&#123;WARN&#125; $&#123;INCLUDE&#125;
CC      &#58;= gcc-3.0
	
$&#123;TARGET&#125;.o&#58; $&#123;TARGET&#125;.c

.PHONY&#58; clean

clean&#58;
    rm -rf &#123;TARGET&#125;.o

if you are using 2.4.x kernel you can use the above Makefile and compile just with

$make

$insmod hello.o

afrolinux

**kokyi2** · 01-31-2005

this time I got this problem
/usr/src/linux- no such file or directory..

**afrolinux** · 01-31-2005

You have to install the linux source code in order to compile any driver. Most of the header files are in that path. I am sure you have in your distro an rpm which is the source code for linux that match with your current kernel. You should install it. May be for this small program you do not need it (I am not sure in kernels 2.6 though) but any other implementations you need those files.

afrolinux

**kokyi2** · 02-04-2005

thanks for ur advice..

**afrolinux** · 02-04-2005

You should post in the same treahd your questions if they are related.

The kernel module should be capable of interact with pci functions in kernel and send back and forth to user space in order to be useful to some user space program. You can do this by implementing :

ioctl's in kernel modules :

http://www.tldp.org/LDP/lkmpg/2.6/html/c878.htm#AEN880

proc file inkernel modules:

http://www.tldp.org/LDP/lkmpg/2.6/html/c740.htm#AEN742

Implementing your own syscalls (Not recomended):

http://www.tldp.org/LDP/lkmpg/2.6/html/c964.htm#AEN966

**sudhindra** · 05-12-2005

hello,

iam writing linux pci driver so i have some doubts

what are the different modules ?

how is the flow of this project?

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