1 files changed, 134 insertions, 0 deletions
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
new file mode 100644
index 000000000000..e47e36a4ef49
--- /dev/null
+++ b/include/scsi/scsi_tcq.h
@@ -0,0 +1,134 @@
+#ifndef _SCSI_SCSI_TCQ_H
+#define _SCSI_SCSI_TCQ_H
+
+#include <linux/blkdev.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+
+
+#define MSG_SIMPLE_TAG	0x20
+#define MSG_HEAD_TAG	0x21
+#define MSG_ORDERED_TAG	0x22
+
+#define SCSI_NO_TAG	(-1)    /* identify no tag in use */
+
+
+
+/**
+ * scsi_get_tag_type - get the type of tag the device supports
+ * @sdev:	the scsi device
+ *
+ * Notes:
+ *	If the drive only supports simple tags, returns MSG_SIMPLE_TAG
+ *	if it supports all tag types, returns MSG_ORDERED_TAG.
+ */
+static inline int scsi_get_tag_type(struct scsi_device *sdev)
+{
+	if (!sdev->tagged_supported)
+		return 0;
+	if (sdev->ordered_tags)
+		return MSG_ORDERED_TAG;
+	if (sdev->simple_tags)
+		return MSG_SIMPLE_TAG;
+	return 0;
+}
+
+static inline void scsi_set_tag_type(struct scsi_device *sdev, int tag)
+{
+	switch (tag) {
+	case MSG_ORDERED_TAG:
+		sdev->ordered_tags = 1;
+		/* fall through */
+	case MSG_SIMPLE_TAG:
+		sdev->simple_tags = 1;
+		break;
+	case 0:
+		/* fall through */
+	default:
+		sdev->ordered_tags = 0;
+		sdev->simple_tags = 0;
+		break;
+	}
+}
+/**
+ * scsi_activate_tcq - turn on tag command queueing
+ * @SDpnt:	device to turn on TCQ for
+ * @depth:	queue depth
+ *
+ * Notes:
+ *	Eventually, I hope depth would be the maximum depth
+ *	the device could cope with and the real queue depth
+ *	would be adjustable from 0 to depth.
+ **/
+static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
+{
+	if (!sdev->tagged_supported)
+		return;
+
+	if (!blk_queue_tagged(sdev->request_queue))
+		blk_queue_init_tags(sdev->request_queue, depth, NULL);
+
+	scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+}
+
+/**
+ * scsi_deactivate_tcq - turn off tag command queueing
+ * @SDpnt:	device to turn off TCQ for
+ **/
+static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
+{
+	if (blk_queue_tagged(sdev->request_queue))
+		blk_queue_free_tags(sdev->request_queue);
+	scsi_adjust_queue_depth(sdev, 0, depth);
+}
+
+/**
+ * scsi_populate_tag_msg - place a tag message in a buffer
+ * @SCpnt:	pointer to the Scsi_Cmnd for the tag
+ * @msg:	pointer to the area to place the tag
+ *
+ * Notes:
+ *	designed to create the correct type of tag message for the 
+ *	particular request.  Returns the size of the tag message.
+ *	May return 0 if TCQ is disabled for this device.
+ **/
+static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
+{
+        struct request *req = cmd->request;
+	struct scsi_device *sdev = cmd->device;
+
+        if (blk_rq_tagged(req)) {
+		if (sdev->ordered_tags && req->flags & REQ_HARDBARRIER)
+        	        *msg++ = MSG_ORDERED_TAG;
+        	else
+        	        *msg++ = MSG_SIMPLE_TAG;
+        	*msg++ = req->tag;
+        	return 2;
+	}
+
+	return 0;
+}
+
+/**
+ * scsi_find_tag - find a tagged command by device
+ * @SDpnt:	pointer to the ScSI device
+ * @tag:	the tag number
+ *
+ * Notes:
+ *	Only works with tags allocated by the generic blk layer.
+ **/
+static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
+{
+
+        struct request *req;
+
+        if (tag != SCSI_NO_TAG) {
+        	req = blk_queue_find_tag(sdev->request_queue, tag);
+	        return req ? (struct scsi_cmnd *)req->special : NULL;
+	}
+
+	/* single command, look in space */
+	return sdev->current_cmnd;
+}
+
+#endif /* _SCSI_SCSI_TCQ_H */