[libata scsi] add ata_scsi_set_sense helper

  - add extern ata_scsi_set_sense() to build SCSI
    fixed sense data and corresponding SCSI status

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 1c3a10f..bca9a50 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -1451,6 +1451,34 @@
 }
 
 /**
+ *	ata_scsi_set_sense - Set SCSI sense data and status
+ *	@cmd: SCSI request to be handled
+ *	@sk: SCSI-defined sense key
+ *	@asc: SCSI-defined additional sense code
+ *	@ascq: SCSI-defined additional sense code qualifier
+ *
+ *	Helper function that builds a valid fixed format, current
+ *	response code and the given sense key (sk), additional sense
+ *	code (asc) and additional sense code qualifier (ascq) with
+ *	a SCSI command status of %SAM_STAT_CHECK_CONDITION and
+ *	DRIVER_SENSE set in the upper bits of scsi_cmnd::result .
+ *
+ *	LOCKING:
+ *	Not required
+ */
+
+void ata_scsi_set_sense(struct scsi_cmnd *cmd, u8 sk, u8 asc, u8 ascq)
+{
+	cmd->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;
+
+	cmd->sense_buffer[0] = 0x70;	/* fixed format, current */
+	cmd->sense_buffer[2] = sk;
+	cmd->sense_buffer[7] = 18 - 8;	/* additional sense length */
+	cmd->sense_buffer[12] = asc;
+	cmd->sense_buffer[13] = ascq;
+}
+
+/**
  *	ata_scsi_badcmd - End a SCSI request with an error
  *	@cmd: SCSI request to be handled
  *	@done: SCSI command completion function