[SCSI] isci: atapi support

Based on original implementation from Jiangbi Liu and Maciej Trela.

ATAPI transfers happen in two-to-three stages.  The two stage atapi
commands are those that include a dma data transfer.  The data transfer
portion of these operations is handled by the hardware packet-dma
acceleration.  The three-stage commands do not have a data transfer and
are handled without hardware assistance in raw frame mode.

stage1: transmit host-to-device fis to notify the device of an incoming
atapi cdb.  Upon reception of the pio-setup-fis repost the task_context
to perform the dma transfer of the cdb+data (go to stage3), or repost
the task_context to transmit the cdb as a raw frame (go to stage 2).

stage2: wait for hardware notification of the cdb transmission and then
go to stage 3.

stage3: wait for the arrival of the terminating device-to-host fis and
terminate the command.

To keep the implementation simple we only support ATAPI packet-dma
protocol (for commands with data) to avoid needing to handle the data
transfer manually (like we do for SATA-PIO).  This may affect
compatibility for a small number of devices (see
ATA_HORKAGE_ATAPI_MOD16_DMA).

If the data-transfer underruns, or encounters an error the
device-to-host fis is expected to arrive in the unsolicited frame queue
to pass to libata for disposition.  However, in the DONE_UNEXP_FIS (data
underrun) case it appears we need to craft a response.  In the
DONE_REG_ERR case we do receive the UF and propagate it to libsas.

Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index d455fa9..c4b7cd0 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -389,6 +389,11 @@ sdev_to_domain_dev(struct scsi_device *sdev) {
 	return starget_to_domain_dev(sdev->sdev_target);
 }
 
+static inline struct ata_device *sas_to_ata_dev(struct domain_device *dev)
+{
+	return &dev->sata_dev.ap->link.device[0];
+}
+
 static inline struct domain_device *
 cmd_to_domain_dev(struct scsi_cmnd *cmd)
 {