Musings on PCI busses

[David Miller]

From: Arnd Bergmann <arnd at arndb.de>
Date: Tue, 19 May 2009 18:12:02 +0200

> On Tuesday 19 May 2009, Grant Likely wrote:
>> 1) Probe the host controller in an of_platform driver.  This has the
>> advantage of simplicity.  The probe routine will get automatically
>> called when the PCI host controller device tree node is registered
>> with the of_platform bus.  The bus parenthood also gets reflected in
>> the device model and sysfs.  The disadvantage is that it defers PCI
>> bus probing until after the of_platform bus is probed (maybe this is
>> okay; maybe this already happens anyway).
> 
> This is also what we do on 64-bit systems (well, Cell at this time).
> There are no fundamental problems with this, just some slightly
> unexpected interactions e.g. when you have use a PCI serial port
> as your console before probing PCI.

This is also what sparc64 does :-)

All of the individual sparc64 PCI controller types have a OF driver
and then there is a common layer of OF PCI helper code to do most
of the work.