newbus ioport usage

[M. Warner Losh]

In message: <20040127141708.O75272 at root.org>
            Nate Lawson <nate at root.org> writes:
: On Tue, 27 Jan 2004, M. Warner Losh wrote:
: > In message: <20040127133251.W75080 at root.org>
: >             Nate Lawson <nate at root.org> writes:
: > : > There's nothing magical about the acpi_sysresource device, and it can
: > : > be relegated to the scrap-heap of history if needed.
: > :
: > : Well, the way we find out about the resources is through a pseudo-device
: > : with a PNPID.  So it makes sense to use the normal device discovery method
: > : to find these resources.  This leads me to do the allocation for the
: > : parent by the acpi_sysresource0 attach method.
: >
: > This gets ugly.  The reason that I suggested not doing the discovery
: > this way is because you want to allocate *ALL* resources up front
: > before giving any to any children.  pci has issues with this right now
: > that I'm working to fix.
: 
: I'm pretty sure there is no other way to know what resources acpi devices
: will be using without evaluating the resource pseudo-device.  The other
: way (which we currently do) is assume everything is available and let each
: driver grab whatever is free and then attach the resource pseudo-device
: last to claim all remaining acpi resources.  Unless you have a better
: idea, the short-term approach will not change any of the above.  It will
: just add the ability for acpi devices to later reclaim resources from
: acpi0 (by having acpi_sysresource0 attach remaining resources to its
: parent).

You could add acpi_sysresource as the first child, which would get
around the issues.  It could then call a private method on its parent
to give it the resources.  But why couldn't that code be moved up into
parent?  I guess I'm not understanding the difficulty here, because
right now there's only one sysresource, and it does:

static int
acpi_sysresource_probe(device_t dev)
{
    if (!acpi_disabled("sysresource") && acpi_MatchHid(dev, "PNP0C02"))
	device_set_desc(dev, "System Resource");
    else
	return (ENXIO);

    device_quiet(dev);
    return (-100);
}

static int
acpi_sysresource_attach(device_t dev)
{
    struct resource	*res;
    int			i, rid;

    /*
     * Suck up all the resources that might have been assigned to us.
     * Note that it's impossible to tell the difference between a
     * resource that someone else has claimed, and one that doesn't
     * exist.
     */
    for (i = 0; i < 100; i++) {
	rid = i;
	res = bus_alloc_resource(dev, SYS_RES_IOPORT, &rid, 0, ~0, 1, 0);
	rid = i;
	res = bus_alloc_resource(dev, SYS_RES_MEMORY, &rid, 0, ~0, 1, 0);
	rid = i;
	res = bus_alloc_resource(dev, SYS_RES_IRQ, &rid, 0, ~0, 1,
				 RF_SHAREABLE);
    }

    return (0);
}

I'm not sure that I see.

: Allocating all resources up front would require multiple passes of the
: namespace and I'm not ready to make that drastic of a change without some
: more design work about how this fits in with the rest of FreeBSD (in
: particular, PCI).

Yes.  We do need to redesign the probe/attach code to have multiple
passes.

Warner