SPARC64: Correct ATU IOTSB binding flow

SPARC64: Correct ATU IOTSB binding flow

Any PCIe device attempting to use ATU for 64-bit DMA must be successfully
bound to IOTSB otherwise DMA access from device will be rejected by
PCIe root complex.

In the current code, ATU initialization and PCIe device binding to IOTSB
is done during system boot when PCI Bus Module (PBM) is initialized.
(PBM driver traverse through the PCI tree and binds each PCI device to
IOTSB).

In case if user/system add SRIOV VFs later on (either after system is up
or when PF driver is loaded), the new VF devices never get bounded to
IOTSB. So when attempt is made from VF devices to access DMA region, ATU
HW will flag it as invalid access; generates CTE_Invalid errors and VF
driver/device fails to perform DMA.

This patch fixes the aforementioned issue by delaying PCIe device
binding to IOTSB only when driver requests DMA setting from kernel.
Doing it this way makes sure every PCIe device requesting 64bit DMA mask
(and therefore attempting to use ATU) will get bind to IOTSB and can do
successful DMA operations.

Orabug: 25177689
Orabug: 25450353

Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Reviewed-by: Govinda Tatti <Govinda.Tatti@Oracle.COM>
Reviewed-by: HÃ¥kon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>