pci_host_generic: Use SYS_RES_MEMORY for the parent of I/O resource ranges

[jhb]

Summary

When a SYS_RES_IOPORT resource crosses a pci_host_generic bridge, it
is translated into a memory access for an associated range, so use
SYS_RES_MEMORY for the resource allocated from the parent. This is
arguably a cleaner solution than having simplebus rewrite
SYS_RES_MEMORY to SYS_RES_IOPORT.

[jrtc27]

What about all the other PCI controller drivers though? Various use ofw_pcib, for example.

[jhb]

ofw_pcib doesn't pass child resources up to simplebus for allocation or activation, it uses bus_space_map directly with a new-bus method to get the bus_space_tag. I think this might be the only one passing SYS_RES_IOPORT up to simplebus and that if this works we might be able to remove all SYS_RES_IOPORT support from simplebus.

[jrtc27]

In D44207#1009367, @jhb wrote:

ofw_pcib doesn't pass child resources up to simplebus for allocation or activation, it uses bus_space_map directly with a new-bus method to get the bus_space_tag. I think this might be the only one passing SYS_RES_IOPORT up to simplebus and that if this works we might be able to remove all SYS_RES_IOPORT support from simplebus.

Should ofw_pcib not be doing it this way too then?

[jhb]

In D44207#1009408, @jrtc27 wrote:

In D44207#1009367, @jhb wrote:

ofw_pcib doesn't pass child resources up to simplebus for allocation or activation, it uses bus_space_map directly with a new-bus method to get the bus_space_tag. I think this might be the only one passing SYS_RES_IOPORT up to simplebus and that if this works we might be able to remove all SYS_RES_IOPORT support from simplebus.

Should ofw_pcib not be doing it this way too then?

I have thought about changing ofw_pcib, but to be clear, ofw_pcib is not passing SYS_RES_IOPORT resources up to its parent bus driver currently.