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 /**
  18  * scsi_get_tag_type - get the type of tag the device supports
  19  * @sdev:       the scsi device
  20  *
  21  * Notes:
  22  *      If the drive only supports simple tags, returns MSG_SIMPLE_TAG
  23  *      if it supports all tag types, returns MSG_ORDERED_TAG.
  24  */
  25 static inline int scsi_get_tag_type(struct scsi_device *sdev)
  26 {
  27         if (!sdev->tagged_supported)
  28                 return 0;
  29         if (sdev->ordered_tags)
  30                 return MSG_ORDERED_TAG;
  31         if (sdev->simple_tags)
  32                 return MSG_SIMPLE_TAG;
  33         return 0;
  34 }
  35
  36 static inline void scsi_set_tag_type(struct scsi_device *sdev, int tag)
  37 {
  38         switch (tag) {
  39         case MSG_ORDERED_TAG:
  40                 sdev->ordered_tags = 1;
  41                 /* fall through */
  42         case MSG_SIMPLE_TAG:
  43                 sdev->simple_tags = 1;
  44                 break;
  45         case 0:
  46                 /* fall through */
  47         default:
  48                 sdev->ordered_tags = 0;
  49                 sdev->simple_tags = 0;
  50                 break;
  51         }
  52 }
  53 /**
  54  * scsi_activate_tcq - turn on tag command queueing
  55  * @SDpnt:      device to turn on TCQ for
  56  * @depth:      queue depth
  57  *
  58  * Notes:
  59  *      Eventually, I hope depth would be the maximum depth
  60  *      the device could cope with and the real queue depth
  61  *      would be adjustable from 0 to depth.
  62  **/
  63 static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
  64 {
  65         if (!sdev->tagged_supported)
  66                 return;
  67
  68         if (!blk_queue_tagged(sdev->request_queue))
  69                 blk_queue_init_tags(sdev->request_queue, depth, NULL);
  70
  71         scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
  72 }
  73
  74 /**
  75  * scsi_deactivate_tcq - turn off tag command queueing
  76  * @SDpnt:      device to turn off TCQ for
  77  **/
  78 static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
  79 {
  80         if (blk_queue_tagged(sdev->request_queue))
  81                 blk_queue_free_tags(sdev->request_queue);
  82         scsi_adjust_queue_depth(sdev, 0, depth);
  83 }
  84
  85 /**
  86  * scsi_populate_tag_msg - place a tag message in a buffer
  87  * @SCpnt:      pointer to the Scsi_Cmnd for the tag
  88  * @msg:        pointer to the area to place the tag
  89  *
  90  * Notes:
  91  *      designed to create the correct type of tag message for the
  92  *      particular request.  Returns the size of the tag message.
  93  *      May return 0 if TCQ is disabled for this device.
  94  **/
  95 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
  96 {
  97         struct request *req = cmd->request;
  98         struct scsi_device *sdev = cmd->device;
  99
 100         if (blk_rq_tagged(req)) {
 101                 if (sdev->ordered_tags && req->flags & REQ_HARDBARRIER)
 102                         *msg++ = MSG_ORDERED_TAG;
 103                 else
 104                         *msg++ = MSG_SIMPLE_TAG;
 105                 *msg++ = req->tag;
 106                 return 2;
 107         }
 108
 109         return 0;
 110 }
 111
 112 /**
 113  * scsi_find_tag - find a tagged command by device
 114  * @SDpnt:      pointer to the ScSI device
 115  * @tag:        the tag number
 116  *
 117  * Notes:
 118  *      Only works with tags allocated by the generic blk layer.
 119  **/
 120 static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
 121 {
 122
 123         struct request *req;
 124
 125         if (tag != SCSI_NO_TAG) {
 126                 req = blk_queue_find_tag(sdev->request_queue, tag);
 127                 return req ? (struct scsi_cmnd *)req->special : NULL;
 128         }
 129
 130         /* single command, look in space */
 131         return sdev->current_cmnd;
 132 }
 133
 134 #endif /* _SCSI_SCSI_TCQ_H */