can't sleep here or we get a DIAGNOSTIC panic when age_watchdog() fires.
More correct bus_dma(9) usage in age_encap()
Introduce a age_shutdown() to be called by pmf(9) at shutdown time,
to stop the DMA engine. My system would't properly reboot without this.
Be consistent in WAIT/NOWAIT use in init routines
Use BUS_DMA_COHERENT where appropriate
Rework the interrupt routine a bit, and ACK but do not disable interrupts
here. There seems to be a race where interrupts would not be properly
reenabled after this, leading do watchdog timeouts.
With these changes, the on-board age(4) on ftp.fr.netbsd.org seems to
be finally working properly.