newbus ioport usage

[Nate Lawson]

On Tue, 27 Jan 2004, M. Warner Losh wrote:
> In message: <E4469364-5092-11D8-8DD8-000393C72BD6 at freebsd.org>
>             Mike Smith <msmith at freebsd.org> writes:
> : The whole reason for the sysresource device was to have something
> : sitting on resources that the AML said had "something" behind them
> : so that they didn't get handed out to devices on eg. PCI.  If you're
> : in the same sort of scope as the sysresource device, it's fair to
> : say that you know more than eg. the PCI bus resource code does about
> : whether you can use the resource in question.
>
> Yes.  It is a form of resource enumeration that belongs to ACPI.
> Therefore, ACPI should manage it and dole it out to its children which
> are based on the AML.  That's what it is there for.  It is akin to the
> PCI code assigning resources based on the BARs that a child has.
> However, only akin, because the entire resource space is enumerated in
> the bus, not the children, for ACPI.  The sysresource stuff was a
> means to an end, not the only way to that end.  I'm starting to think
> that the right way to go is to reserve EVERYTHING up front, and then
> have all the acpi_foo devices allocate out of that reserveation.
>
> In this way it is similar to a BAR that has been assigned by the BIOS,
> but isn't allocated by a child device on pci.  In the code I'm working
> on, those resources are reserved at the bus level and given to the
> child if it asks for it later.  Well, it is a little more complex than
> that because the child device actually owns the resource, but the bus
> is who assigns ownership.  In ACPI, since the resource maps aren't
> child specific, the ownership should resided in the bus layer.  So
> instead of belonging to acpi_sysresource0, it would belong to acpi0.
> This may also help some downstream resource allocations, since they
> would now be happening a little earlier in the game.

Ok, let me propose a design and I'd appreciate your comments.  The probe
routine for acpi_sysresource will stay the same.  The attach will allocate
the resources to its parent device (acpi0).

acpi0 will make this set of resources available to its children via a
flag included with bus_alloc_resource, say ACPIDEV_REQUEST.  If
acpi_resource_alloc finds a range already has that flag set, it will
refuse the request.  Otherwise, it will release that range and then
immediately allocate it to the child.

-Nate