Accesiing the IO space of SMbus host controller

Hi,
I need to develop a driver to read and write to a SMbus host controller.
I have VIA VX855 chipset.My device is in the IO space of PCI bus 0 device 17
function 0.
My device is in the motherboard so it is always connected.so it is not shown
in the device manager.

I looked into portIO driver but I am not sure how to get the base address of
my device in the driver since it is not plug and play?

Can anyone suggest me what should be my approach towards this?

Thanks,
vbkr



Do I need to write a PCI function driver or portIO driver

vbkr <> wrote:
>
>I need to develop a driver to read and write to a SMbus host controller.
>I have VIA VX855 chipset.My device is in the IO space of PCI bus 0 device 17
>function 0.
>My device is in the motherboard so it is always connected.so it is not shown
>in the device manager.
>
>I looked into portIO driver but I am not sure how to get the base address of
>my device in the driver since it is not plug and play?
>
>Can anyone suggest me what should be my approach towards this?
>
>Do I need to write a PCI function driver or portIO driver

We've just had a rather frustrating exchange on the NTDEV list about this.
SMbus is a shadowy world that has a visceral existence somewhere between
BIOS and kernel, and that makes it rather difficult to access reliably.

Why do you need to read and write this space? What do you need to
accomplish?

If you know the I/O address, you can use portIO to access it. But if you
need to use PCI configuration space to find the I/O port number, that's a
more difficult problem. You can use HalGetBusData, although that's not
guaranteed safe.
--
Tim Roberts,
Providenza & Boekelheide, Inc.

Hi Tim,
I have tried to read the PCI config space but I get 0xffff as the return
value.
I have written a filter driver to PCIbus and a function driver which is run
as a service.
I have used IRP_MN_QUERY_INTERFACE ,ReadConfig and WriteConfig routines to
access it.
I also tried to read different PCI devices VID and DID but I get the same
0xffff as return value.

I am trying this on windows 7.

Any suggestions?

Thanks,
vbkr

"Tim Roberts" wrote:

> vbkr <> wrote:
> >
> >I need to develop a driver to read and write to a SMbus host controller.
> >I have VIA VX855 chipset.My device is in the IO space of PCI bus 0 device 17
> >function 0.
> >My device is in the motherboard so it is always connected.so it is not shown
> >in the device manager.
> >
> >I looked into portIO driver but I am not sure how to get the base address of
> >my device in the driver since it is not plug and play?
> >
> >Can anyone suggest me what should be my approach towards this?
> >
> >Do I need to write a PCI function driver or portIO driver
>
> We've just had a rather frustrating exchange on the NTDEV list about this.
> SMbus is a shadowy world that has a visceral existence somewhere between
> BIOS and kernel, and that makes it rather difficult to access reliably.
>
> Why do you need to read and write this space? What do you need to
> accomplish?
>
> If you know the I/O address, you can use portIO to access it. But if you
> need to use PCI configuration space to find the I/O port number, that's a
> more difficult problem. You can use HalGetBusData, although that's not
> guaranteed safe.
> --
> Tim Roberts,
> Providenza & Boekelheide, Inc.
> .
>

Hi Tim,
My basic aim was to read and write to IO address 0x400.
When I try to see in the device manager view by type.I did see that the
port IO address is shown as motherboard resources(0x400-0x41F).
This is only for prototype environment.

how do I access this address and assign these resources to my port driver?

I would appreciate your help and time you spend.
Thanks,
vbkr

"vbkr" wrote:

> Hi Tim,
> I have tried to read the PCI config space but I get 0xffff as the return
> value.
> I have written a filter driver to PCIbus and a function driver which is run
> as a service.
> I have used IRP_MN_QUERY_INTERFACE ,ReadConfig and WriteConfig routines to
> access it.
> I also tried to read different PCI devices VID and DID but I get the same
> 0xffff as return value.
>
> I am trying this on windows 7.
>
> Any suggestions?
>
> Thanks,
> vbkr
>
> "Tim Roberts" wrote:
>
> > vbkr <> wrote:
> > >
> > >I need to develop a driver to read and write to a SMbus host controller.
> > >I have VIA VX855 chipset.My device is in the IO space of PCI bus 0 device 17
> > >function 0.
> > >My device is in the motherboard so it is always connected.so it is not shown
> > >in the device manager.
> > >
> > >I looked into portIO driver but I am not sure how to get the base address of
> > >my device in the driver since it is not plug and play?
> > >
> > >Can anyone suggest me what should be my approach towards this?
> > >
> > >Do I need to write a PCI function driver or portIO driver
> >
> > We've just had a rather frustrating exchange on the NTDEV list about this.
> > SMbus is a shadowy world that has a visceral existence somewhere between
> > BIOS and kernel, and that makes it rather difficult to access reliably.
> >
> > Why do you need to read and write this space? What do you need to
> > accomplish?
> >
> > If you know the I/O address, you can use portIO to access it. But if you
> > need to use PCI configuration space to find the I/O port number, that's a
> > more difficult problem. You can use HalGetBusData, although that's not
> > guaranteed safe.
> > --
> > Tim Roberts,
> > Providenza & Boekelheide, Inc.
> > .
> >

vbkr <> wrote:
>
>My basic aim was to read and write to IO address 0x400.
>When I try to see in the device manager view by type.I did see that the
>port IO address is shown as motherboard resources(0x400-0x41F).
>This is only for prototype environment.
>
>how do I access this address and assign these resources to my port driver?

From a driver, if you know that's the address you need, you just call
READ_PORT_ULONG (or USHORT or UCHAR) with register number 0x400. You don't
actually need a reservation to access the port.

Now, you need to understand that you're stepping on a port that belongs to
another driver. That's not safe. But if you're just experimenting, have
at it.
--
Tim Roberts,
Providenza & Boekelheide, Inc.