[newb] mmap pci

[newb] mmap pci

[Neal Becker]

We have a device - an FPGA board on PCI bus.  It has a range of internal
memory mapped to PCI.  I want to expose this to user via mmap.  Is there
some example code someone could point me to?

If this is not the best forum for such questions, what would be a better
choice?

Re: [newb] mmap pci

[Arjan van de Ven]

On Wed, 16 Apr 2008 07:23:29 -0400
Neal Becker <ndbecker2@gmail.com> wrote:

> We have a device - an FPGA board on PCI bus.  It has a range of
> internal memory mapped to PCI.  I want to expose this to user via
> mmap.  Is there some example code someone could point me to?
> 
> If this is not the best forum for such questions, what would be a
> better choice?

Hi,

if it's just a PCI bar, you can already memory map it without even writing a driver!
You can just use the sysfs files for this, for example
/sys/devices/pci0000:00/0000:00:02.0/resource1

There's also a way to do this via the /proc representation of the PCI device..

Greetings,
   Arjan van de Ven


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Re: [newb] mmap pci

[Neal Becker]

Arjan van de Ven wrote:

> On Wed, 16 Apr 2008 07:23:29 -0400
> Neal Becker <ndbecker2@gmail.com> wrote:
> 
>> We have a device - an FPGA board on PCI bus.  It has a range of
>> internal memory mapped to PCI.  I want to expose this to user via
>> mmap.  Is there some example code someone could point me to?
>> 
>> If this is not the best forum for such questions, what would be a
>> better choice?
> 
> Hi,
> 
> if it's just a PCI bar, you can already memory map it without even writing
> a driver! You can just use the sysfs files for this, for example
> /sys/devices/pci0000:00/0000:00:02.0/resource1
> 
> There's also a way to do this via the /proc representation of the PCI
> device..
> 
> Greetings,
>    Arjan van de Ven
> 
> 

Thanks!  Only problem: seems the mapping is read-only?
This python test code works if prot=mmap.PROT_READ, but I get
permission denied if PROT_READ|PROT_WRITE.

import mmap
import struct

f = open ('/sys/bus/pci/devices/0000:05:0f.0/resource0','rw')
m = mmap.mmap(f.fileno(), 1000000, prot=mmap.PROT_READ)