[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>

drivers/scsi/isci/remote_device.c

@@ -386,6 +386,18 @@ static bool is_remote_device_ready(struct isci_remote_device *idev)
 	}
 }
 
+/*
+ * called once the remote node context has transisitioned to a ready
+ * state (after suspending RX and/or TX due to early D2H fis)
+ */
+static void atapi_remote_device_resume_done(void *_dev)
+{
+	struct isci_remote_device *idev = _dev;
+	struct isci_request *ireq = idev->working_request;
+
+	sci_change_state(&ireq->sm, SCI_REQ_COMPLETED);
+}
+
 enum sci_status sci_remote_device_event_handler(struct isci_remote_device *idev,
 						     u32 event_code)
 {
@@ -432,6 +444,16 @@ enum sci_status sci_remote_device_event_handler(struct isci_remote_device *idev,
 	if (status != SCI_SUCCESS)
 		return status;
 
+	if (state == SCI_STP_DEV_ATAPI_ERROR) {
+		/* For ATAPI error state resume the RNC right away. */
+		if (scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX ||
+		    scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX_RX) {
+			return sci_remote_node_context_resume(&idev->rnc,
+							      atapi_remote_device_resume_done,
+							      idev);
+		}
+	}
+
 	if (state == SCI_STP_DEV_IDLE) {
 
 		/* We pick up suspension events to handle specifically to this
@@ -625,6 +647,7 @@ enum sci_status sci_remote_device_complete_io(struct isci_host *ihost,
 	case SCI_STP_DEV_CMD:
 	case SCI_STP_DEV_NCQ:
 	case SCI_STP_DEV_NCQ_ERROR:
+	case SCI_STP_DEV_ATAPI_ERROR:
 		status = common_complete_io(iport, idev, ireq);
 		if (status != SCI_SUCCESS)
 			break;
@@ -1020,6 +1043,7 @@ static const struct sci_base_state sci_remote_device_state_table[] = {
 	[SCI_STP_DEV_NCQ_ERROR] = {
 		.enter_state = sci_stp_remote_device_ready_ncq_error_substate_enter,
 	},
+	[SCI_STP_DEV_ATAPI_ERROR] = { },
 	[SCI_STP_DEV_AWAIT_RESET] = { },
 	[SCI_SMP_DEV_IDLE] = {
 		.enter_state = sci_smp_remote_device_ready_idle_substate_enter,

drivers/scsi/isci/remote_device.h

@@ -243,6 +243,15 @@ enum sci_remote_device_states {
 	 */
 	SCI_STP_DEV_NCQ_ERROR,
 
+	/**
+	 * This is the ATAPI error state for the STP ATAPI remote device.
+	 * This state is entered when ATAPI device sends error status FIS
+	 * without data while the device object is in CMD state.
+	 * A suspension event is expected in this state.
+	 * The device object will resume right away.
+	 */
+	SCI_STP_DEV_ATAPI_ERROR,
+
 	/**
 	 * This is the READY substate indicates the device is waiting for the RESET task
 	 * coming to be recovered from certain hardware specific error.