PCI device search.

PCI device search.

[Stelian Pop]

Hi,

I have a device driver (drivers/char/sonypi in this case)
which can handle two cases:
	- on older hardware, it gets attached to a specific 
	  PCI device

	- on newer hardware, when the previous PCI device
	  is missing, it just uses a predefined set of
	  ioports to access the hardware. There is no PCI
	  device involved here.

I am wondering what is the cleanest way to program this. 
As I see it, I have two distinct choices:

	1. Create a PCI driver (pci_device_id, struct pci_driver etc)
	and in init_module call pci_module_init. If it fails,
	assume the driver deals with newer hardware and 
	call 'by hand' the 'probe' routine from pci_driver struct.

	2. Not use the PCI driver infrastructure, and in
	init_module just call pci_find_device manually searching
	for older hardware, if it is present go further, if
	it fails assume newer hardware and go further.

What is considered to be the best way to do it ?
(this is _not_ a hotplug device if it matters).

Thanks,

Stelian.
-- 
Stelian Pop <stelian.pop@fr.alcove.com>
|---------------- Free Software Engineer -----------------|
| Alcôve - http://www.alcove.com - Tel: +33 1 49 22 68 00 |
|------------- Alcôve, liberating software ---------------|

Re: PCI device search.

[Greg KH]

On Fri, Oct 12, 2001 at 05:04:11PM +0200, Stelian Pop wrote:
> 
> 	1. Create a PCI driver (pci_device_id, struct pci_driver etc)
> 	and in init_module call pci_module_init. If it fails,
> 	assume the driver deals with newer hardware and 
> 	call 'by hand' the 'probe' routine from pci_driver struct.
> 
> 	2. Not use the PCI driver infrastructure, and in
> 	init_module just call pci_find_device manually searching
> 	for older hardware, if it is present go further, if
> 	it fails assume newer hardware and go further.
> 
> What is considered to be the best way to do it ?
> (this is _not_ a hotplug device if it matters).

I'd say 1.  If a device is hotpluggable or not does not matter.  For
2.5, the boot process will be able to load modules for all PCI
devices seen in the system.  In order for that to happen, they need to
use the MODULE_DEVICE structure and the 2.4 pci driver subsystem.

(which it looks like almost none of the current SCSI driver do...)

thanks,

greg k-h

Re: PCI device search.

[Jeff Garzik]

On Fri, 12 Oct 2001, Greg KH wrote:
> On Fri, Oct 12, 2001 at 05:04:11PM +0200, Stelian Pop wrote:
> > 	1. Create a PCI driver (pci_device_id, struct pci_driver etc)
> > 	and in init_module call pci_module_init. If it fails,
> > 	assume the driver deals with newer hardware and 
> > 	call 'by hand' the 'probe' routine from pci_driver struct.

> > What is considered to be the best way to do it ?
> > (this is _not_ a hotplug device if it matters).

> I'd say 1.  If a device is hotpluggable or not does not matter.  For
> 2.5, the boot process will be able to load modules for all PCI
> devices seen in the system.  In order for that to happen, they need to
> use the MODULE_DEVICE structure and the 2.4 pci driver subsystem.

I'd say 1.5.  :)  For the "newer hardware" consider using the PCI host
bridge or ISA bridge for your "container" PCI device.

	Jeff

Re: PCI device search.

[Stelian Pop]

On Fri, Oct 12, 2001 at 04:15:54PM -0500, Jeff Garzik wrote:

> > I'd say 1.  If a device is hotpluggable or not does not matter.  For
> > 2.5, the boot process will be able to load modules for all PCI
> > devices seen in the system.  In order for that to happen, they need to
> > use the MODULE_DEVICE structure and the 2.4 pci driver subsystem.
> 
> I'd say 1.5.  :)  For the "newer hardware" consider using the PCI host
> bridge or ISA bridge for your "container" PCI device.

You mean putting PCI_CLASS_BRIDGE_PCI as pattern in the pci
search table, yes ?

Thanks.

Stelian.
-- 
Stelian Pop <stelian.pop@fr.alcove.com>
|---------------- Free Software Engineer -----------------|
| Alcôve - http://www.alcove.com - Tel: +33 1 49 22 68 00 |
|------------- Alcôve, liberating software ---------------|

Re: PCI device search.

[Jeff Garzik]

On Sat, 13 Oct 2001, Stelian Pop wrote:

> On Fri, Oct 12, 2001 at 04:15:54PM -0500, Jeff Garzik wrote:
> 
> > > I'd say 1.  If a device is hotpluggable or not does not matter.  For
> > > 2.5, the boot process will be able to load modules for all PCI
> > > devices seen in the system.  In order for that to happen, they need to
> > > use the MODULE_DEVICE structure and the 2.4 pci driver subsystem.
> > 
> > I'd say 1.5.  :)  For the "newer hardware" consider using the PCI host
> > bridge or ISA bridge for your "container" PCI device.
> 
> You mean putting PCI_CLASS_BRIDGE_PCI as pattern in the pci
> search table, yes ?

Close but not quite.  Look at drivers/char/i810_rng.c.  It uses PCI ids
for Intel PCI bridge to search for, since the RNG itself doesn't have a
PCI id.

	Jeff