Reading acpi memory from a driver attached to hostb

[Rui Paulo]

On 18 Jul 2009, at 09:10, Andre Albsmeier wrote:

> On Fri, 17-Jul-2009 at 12:53:53 -0700, Julian Elischer wrote:
>> Andre Albsmeier wrote:
>>> [CC'ing this to Rui Paulo since he tried to help me a while ago]
>>>
>>> Since my driver is a child of hostb0, I have no idea of how to  
>>> access
>>> acpi0's memory area. Here is a devinfo -r to make things clear:
>>>
>> ...
>>>
>>> Earlier, I was given the hint to attach as a child of acpi (see the
>>> old mail attached below) but in this case I didn't have access to  
>>> the
>>> hostb registers which I need as well.
>>>
>>> The only thing I see is: Attach two drivers -- one as child of acpi
>>> and another as child of hostb and let them communicate somehow (no
>>> idea how to do this).
>>>
>>> I have also done crazy things like searching for acpi0 and trying
>>> to bus_alloc_resource() the memory I am interested in but this also
>>> failed.
>>>
>>> Or is it possible to free(!) somehow the address space from acpi0
>>> and pass it to hostb0 so I can bus_alloc_resource() it?
>>>
>>
>> You can probably make two drivers in one which cooperate to
>> allow access to both sets of resources.
>
> Hmm, that's what I meant by: Attach two drivers -- one as child of  
> acpi
> and another as child of hostb...
>
> And that's similar to Rui Paulo's suggestion a while ago:
>
>> You'll probably need to create a fake ACPI child driver to access it.
>>
>> Create your identify routine with something like:
>>
>> static void mydriver_identify(driver_t *driver, device_t parent)
>> {
>>        if (device_find_child(parent, "mydriver", -1) == NULL &&
>>            mydriver_match(parent))
>>                device_add_child(parent, "mydriver", -1);
>> }
>>
>> mydriver_match() should check if you were given the acpi0 device.
>
> But in order to attach to acpi0, I need to say
>
> DRIVER_MODULE( eccmon, acpi, eccmon_driver, eccmon_devclass,  NULL,  
> NULL );
>
> instead of
>
> DRIVER_MODULE( eccmon, hostb, eccmon_driver, eccmon_devclass,  NULL,  
> NULL );
>
> This way I could attach to acpi but not to hostb anymore....
>
> I have searched the net for solutions, I have read newbus-draft.txt
> and newbus-intro.txt and Warner Losh's newbus-led.c (thanks to all
> of these my driver is working on other mainboards where it doesn't
> have to access foreign memory) but didn't find anything.

I'm out of ideas.
John, do you know if this is a newbus limitation or if it can be  
worked around ?

--
Rui Paulo