include/scsi/scsi_tcq.h

   1 #ifndef _SCSI_SCSI_TCQ_H
   2 #define _SCSI_SCSI_TCQ_H
   3
   4 #include <linux/blkdev.h>
   5 #include <scsi/scsi_cmnd.h>
   6 #include <scsi/scsi_device.h>
   7
   8
   9 #define MSG_SIMPLE_TAG  0x20
  10 #define MSG_HEAD_TAG    0x21
  11 #define MSG_ORDERED_TAG 0x22
  12
  13 #define SCSI_NO_TAG     (-1)    /* identify no tag in use */
  14
  15
  16 /**
  17  * scsi_activate_tcq - turn on tag command queueing
  18  * @SDpnt:      device to turn on TCQ for
  19  * @depth:      queue depth
  20  *
  21  * Notes:
  22  *      Eventually, I hope depth would be the maximum depth
  23  *      the device could cope with and the real queue depth
  24  *      would be adjustable from 0 to depth.
  25  **/
  26 static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
  27 {
  28         if (sdev->tagged_supported) {
  29                 if (!blk_queue_tagged(sdev->request_queue))
  30                         blk_queue_init_tags(sdev->request_queue, depth, NULL);
  31                 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
  32         }
  33 }
  34
  35 /**
  36  * scsi_deactivate_tcq - turn off tag command queueing
  37  * @SDpnt:      device to turn off TCQ for
  38  **/
  39 static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
  40 {
  41         if (blk_queue_tagged(sdev->request_queue))
  42                 blk_queue_free_tags(sdev->request_queue);
  43         scsi_adjust_queue_depth(sdev, 0, depth);
  44 }
  45
  46 /**
  47  * scsi_populate_tag_msg - place a tag message in a buffer
  48  * @SCpnt:      pointer to the Scsi_Cmnd for the tag
  49  * @msg:        pointer to the area to place the tag
  50  *
  51  * Notes:
  52  *      designed to create the correct type of tag message for the
  53  *      particular request.  Returns the size of the tag message.
  54  *      May return 0 if TCQ is disabled for this device.
  55  **/
  56 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
  57 {
  58         struct request *req = cmd->request;
  59
  60         if (blk_rq_tagged(req)) {
  61                 if (req->flags & REQ_HARDBARRIER)
  62                         *msg++ = MSG_ORDERED_TAG;
  63                 else
  64                         *msg++ = MSG_SIMPLE_TAG;
  65                 *msg++ = req->tag;
  66                 return 2;
  67         }
  68
  69         return 0;
  70 }
  71
  72 /**
  73  * scsi_find_tag - find a tagged command by device
  74  * @SDpnt:      pointer to the ScSI device
  75  * @tag:        the tag number
  76  *
  77  * Notes:
  78  *      Only works with tags allocated by the generic blk layer.
  79  **/
  80 static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
  81 {
  82
  83         struct request *req;
  84
  85         if (tag != SCSI_NO_TAG) {
  86                 req = blk_queue_find_tag(sdev->request_queue, tag);
  87                 return req ? (struct scsi_cmnd *)req->special : NULL;
  88         }
  89
  90         /* single command, look in space */
  91         return sdev->current_cmnd;
  92 }
  93
  94 #endif /* _SCSI_SCSI_TCQ_H */