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-rw-r--r--include/scsi/scsi_tcq.h134
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 0000000..e47e36a
--- /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 */
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