This fixes a `hang' on shutdown when the `Synchronise Cache' command
is sent to a disk. (It uses polled mode because it is called from inside
a shutdown hook).
This is based on amiga's siop driver, but converted to use
bus_space(9) functions and modified to fit bus_dma(9) framework.
Currently tested on NetBSD/arc with jazzio 53c710 SCSI,
which really requires bus_dma(9) functions :-)
Sync transfers and disconnect/reconnect are also working.
TODO:
- Test under more heavy load
- Clean up osiop_checkintr() hander
- Reorganize command queue and sync negotiation handling more suitable
for thorpej-scsipi mid-layer
- Re-think defered interrupt handling for amiga
tsutsui