libata: Add support for SATA attachment to SAS adapters

This is a repost of the patchset I have been carrying. No real feature changes here, mainly just a refresh against Jeff's #upstream libata git tree. I've been running with these patches for a while now without problems.

The following patchset enhances libata to allow SAS device drivers to utilize libata to talk to SATA devices. It introduces some new APIs which allow libata to be used without allocating a virtual scsi host.

New APIs:

ata_sas_port_alloc - Allocate an ata_port
ata_sas_port_init - Initialize an ata_port (probe device, etc) ata_sas_port_destroy - Free an ata_port allocated by ata_sas_port_alloc ata_sas_slave_configure - configure scsi device ata_sas_queuecmd - queue a scsi command, similar to ata_scsi_queuecomand

These new APIs can be used either directly by a SAS LLDD or could be used by the SAS transport class.

Possible usage for a SAS LLDD would be:

scsi_scan_host
target_alloc
ata_sas_port_alloc
slave_alloc
ata_sas_port_init
slave_configure
ata_sas_slave_configure

Commands received by the LLDD for SATA devices would call ata_sas_queuecmd.

Device teardown would occur with:

slave_destroy
port_disable
target_destroy
ata_sas_port_destroy

Brian King
eServer Storage I/O
IBM Linux Technology Center