Per ATA host sysfs attributes?

[Mark Lord <liml@rtr.ca>]

Guys,

I have added IRQ coalescing to sata_mv, but need a way to activate/tune it.
There are two simple parameters:  an IRQ count threshold, and a time threshold.

Whenever either the count or the time threshold is exceeded,
the chip will generate an interrupt (assuming at least one completed event).

These two parameters are per-chip (actually, per group of four ports within the chip).
How can I export these for setting/query withing sysfs ?

It is all rather easy to create per-SCSI-host attrs in sysfs,
but I don't see any obvious way to do it per-chip. 

Suggestions?

For now, I'm doing it with a module parameter,
but that's really rather stone-age in the sysfs era.

Thanks.