DRIVE_OLD, DRIVE_ATA or DRIVE_ATAPI based on register signatures.
The attach routine will issue a IDENTIFY command for ATA/ATAPI disk,
to detect flase matches by the probe routine.
probe/attach should now be fully compliant with ata-4/ata-5. As a side
effect, ATAPI drives which improperly use ATA register signatures should now
be attached as ATAPI.
the disk is ready to transfer data, and in ATA-5 the DSC has been obsoleted.
So only wait for DRQ to transfer data. This can be made conditional on the
ATA version if it's proven to break with some drives (worked with all the
drives I have access to).
While I'm there correct a few typos.
In wdc_probe_caps() add code to guess the ATA revision supported (if
ATA4 if Ultra-DMA, ATA2 if PIO mode > 2). We can't rely on param.atap_ata_major
here, at last one Ultra-DMA drive claims to support only ATA-3.
Use the ATA version in ata_perror(), and to try a flush cache command
in a shutdown hook for IDE drives.
