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 #include <scsi/scsi_host.h>
   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 #ifdef CONFIG_BLOCK
  17
  18 /**
  19  * scsi_get_tag_type - get the type of tag the device supports
  20  * @sdev:       the scsi device
  21  *
  22  * Notes:
  23  *      If the drive only supports simple tags, returns MSG_SIMPLE_TAG
  24  *      if it supports all tag types, returns MSG_ORDERED_TAG.
  25  */
  26 static inline int scsi_get_tag_type(struct scsi_device *sdev)
  27 {
  28         if (!sdev->tagged_supported)
  29                 return 0;
  30         if (sdev->ordered_tags)
  31                 return MSG_ORDERED_TAG;
  32         if (sdev->simple_tags)
  33                 return MSG_SIMPLE_TAG;
  34         return 0;
  35 }
  36
  37 static inline void scsi_set_tag_type(struct scsi_device *sdev, int tag)
  38 {
  39         switch (tag) {
  40         case MSG_ORDERED_TAG:
  41                 sdev->ordered_tags = 1;
  42                 /* fall through */
  43         case MSG_SIMPLE_TAG:
  44                 sdev->simple_tags = 1;
  45                 break;
  46         case 0:
  47                 /* fall through */
  48         default:
  49                 sdev->ordered_tags = 0;
  50                 sdev->simple_tags = 0;
  51                 break;
  52         }
  53 }
  54 /**
  55  * scsi_activate_tcq - turn on tag command queueing
  56  * @SDpnt:      device to turn on TCQ for
  57  * @depth:      queue depth
  58  *
  59  * Notes:
  60  *      Eventually, I hope depth would be the maximum depth
  61  *      the device could cope with and the real queue depth
  62  *      would be adjustable from 0 to depth.
  63  **/
  64 static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
  65 {
  66         if (!sdev->tagged_supported)
  67                 return;
  68
  69         if (!blk_queue_tagged(sdev->request_queue))
  70                 blk_queue_init_tags(sdev->request_queue, depth,
  71                                     sdev->host->bqt);
  72
  73         scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
  74 }
  75
  76 /**
  77  * scsi_deactivate_tcq - turn off tag command queueing
  78  * @SDpnt:      device to turn off TCQ for
  79  **/
  80 static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
  81 {
  82         if (blk_queue_tagged(sdev->request_queue))
  83                 blk_queue_free_tags(sdev->request_queue);
  84         scsi_adjust_queue_depth(sdev, 0, depth);
  85 }
  86
  87 /**
  88  * scsi_populate_tag_msg - place a tag message in a buffer
  89  * @SCpnt:      pointer to the Scsi_Cmnd for the tag
  90  * @msg:        pointer to the area to place the tag
  91  *
  92  * Notes:
  93  *      designed to create the correct type of tag message for the
  94  *      particular request.  Returns the size of the tag message.
  95  *      May return 0 if TCQ is disabled for this device.
  96  **/
  97 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
  98 {
  99         struct request *req = cmd->request;
 100
 101         if (blk_rq_tagged(req)) {
 102                 *msg++ = MSG_SIMPLE_TAG;
 103                 *msg++ = req->tag;
 104                 return 2;
 105         }
 106
 107         return 0;
 108 }
 109
 110 /**
 111  * scsi_find_tag - find a tagged command by device
 112  * @SDpnt:      pointer to the ScSI device
 113  * @tag:        the tag number
 114  *
 115  * Notes:
 116  *      Only works with tags allocated by the generic blk layer.
 117  **/
 118 static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
 119 {
 120
 121         struct request *req;
 122
 123         if (tag != SCSI_NO_TAG) {
 124                 req = blk_queue_find_tag(sdev->request_queue, tag);
 125                 return req ? (struct scsi_cmnd *)req->special : NULL;
 126         }
 127
 128         /* single command, look in space */
 129         return sdev->current_cmnd;
 130 }
 131
 132 /**
 133  * scsi_init_shared_tag_map - create a shared tag map
 134  * @shost:      the host to share the tag map among all devices
 135  * @depth:      the total depth of the map
 136  */
 137 static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
 138 {
 139         /*
 140          * If the shared tag map isn't already initialized, do it now.
 141          * This saves callers from having to check ->bqt when setting up
 142          * devices on the shared host (for libata)
 143          */
 144         if (!shost->bqt) {
 145                 shost->bqt = blk_init_tags(depth);
 146                 if (!shost->bqt)
 147                         return -ENOMEM;
 148         }
 149
 150         return 0;
 151 }
 152
 153 /**
 154  * scsi_host_find_tag - find the tagged command by host
 155  * @shost:      pointer to scsi_host
 156  * @tag:        tag of the scsi_cmnd
 157  *
 158  * Notes:
 159  *      Only works with tags allocated by the generic blk layer.
 160  **/
 161 static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
 162                                                 int tag)
 163 {
 164         struct request *req;
 165
 166         if (tag != SCSI_NO_TAG) {
 167                 req = blk_map_queue_find_tag(shost->bqt, tag);
 168                 return req ? (struct scsi_cmnd *)req->special : NULL;
 169         }
 170         return NULL;
 171 }
 172
 173 #endif /* CONFIG_BLOCK */
 174 #endif /* _SCSI_SCSI_TCQ_H */