DDB when the interrupt button (aka the "programmer's switch") is pressed.
This isn't unfortunately an NMI, but it's a handy way to get into DDB
quickly if needed.
- Store the OpenFirmware "reg" property in the macio ivars.
- Use a struct to define the structure of a "reg" property entry.
- Discover all memory ranges, not just the first.
- In ata_macio, manage our own range and hand out our own allocations using
bus_space_subregion.
- Fix bus_space_subregion to handle subregions of sparse maps.
- Add a quirk type for devices whose interrupt properties are actually
attached to their children.
- Flag the "escc" (zs-alike serial controller) device as having this quirk.
- Rework the interrupt discovery code to deal with devices that have more than
one interrupt.
