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 #define MSG_ACA_TAG     0x24    /* unsupported */
  13
  14 #define SCSI_NO_TAG     (-1)    /* identify no tag in use */
  15
  16
  17 #ifdef CONFIG_BLOCK
  18
  19 /**
  20  * scsi_get_tag_type - get the type of tag the device supports
  21  * @sdev:       the scsi device
  22  *
  23  * Notes:
  24  *      If the drive only supports simple tags, returns MSG_SIMPLE_TAG
  25  *      if it supports all tag types, returns MSG_ORDERED_TAG.
  26  */
  27 static inline int scsi_get_tag_type(struct scsi_device *sdev)
  28 {
  29         if (!sdev->tagged_supported)
  30                 return 0;
  31         if (sdev->ordered_tags)
  32                 return MSG_ORDERED_TAG;
  33         if (sdev->simple_tags)
  34                 return MSG_SIMPLE_TAG;
  35         return 0;
  36 }
  37
  38 static inline void scsi_set_tag_type(struct scsi_device *sdev, int tag)
  39 {
  40         switch (tag) {
  41         case MSG_ORDERED_TAG:
  42                 sdev->ordered_tags = 1;
  43                 /* fall through */
  44         case MSG_SIMPLE_TAG:
  45                 sdev->simple_tags = 1;
  46                 break;
  47         case 0:
  48                 /* fall through */
  49         default:
  50                 sdev->ordered_tags = 0;
  51                 sdev->simple_tags = 0;
  52                 break;
  53         }
  54 }
  55 /**
  56  * scsi_activate_tcq - turn on tag command queueing
  57  * @SDpnt:      device to turn on TCQ for
  58  * @depth:      queue depth
  59  *
  60  * Notes:
  61  *      Eventually, I hope depth would be the maximum depth
  62  *      the device could cope with and the real queue depth
  63  *      would be adjustable from 0 to depth.
  64  **/
  65 static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
  66 {
  67         if (!sdev->tagged_supported)
  68                 return;
  69
  70         if (!blk_queue_tagged(sdev->request_queue))
  71                 blk_queue_init_tags(sdev->request_queue, depth,
  72                                     sdev->host->bqt);
  73
  74         scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
  75 }
  76
  77 /**
  78  * scsi_deactivate_tcq - turn off tag command queueing
  79  * @SDpnt:      device to turn off TCQ for
  80  **/
  81 static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
  82 {
  83         if (blk_queue_tagged(sdev->request_queue))
  84                 blk_queue_free_tags(sdev->request_queue);
  85         scsi_adjust_queue_depth(sdev, 0, depth);
  86 }
  87
  88 /**
  89  * scsi_populate_tag_msg - place a tag message in a buffer
  90  * @SCpnt:      pointer to the Scsi_Cmnd for the tag
  91  * @msg:        pointer to the area to place the tag
  92  *
  93  * Notes:
  94  *      designed to create the correct type of tag message for the
  95  *      particular request.  Returns the size of the tag message.
  96  *      May return 0 if TCQ is disabled for this device.
  97  **/
  98 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
  99 {
 100         struct request *req = cmd->request;
 101
 102         if (blk_rq_tagged(req)) {
 103                 *msg++ = MSG_SIMPLE_TAG;
 104                 *msg++ = req->tag;
 105                 return 2;
 106         }
 107
 108         return 0;
 109 }
 110
 111 /**
 112  * scsi_find_tag - find a tagged command by device
 113  * @SDpnt:      pointer to the ScSI device
 114  * @tag:        the tag number
 115  *
 116  * Notes:
 117  *      Only works with tags allocated by the generic blk layer.
 118  **/
 119 static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
 120 {
 121
 122         struct request *req;
 123
 124         if (tag != SCSI_NO_TAG) {
 125                 req = blk_queue_find_tag(sdev->request_queue, tag);
 126                 return req ? (struct scsi_cmnd *)req->special : NULL;
 127         }
 128
 129         /* single command, look in space */
 130         return sdev->current_cmnd;
 131 }
 132
 133 /**
 134  * scsi_init_shared_tag_map - create a shared tag map
 135  * @shost:      the host to share the tag map among all devices
 136  * @depth:      the total depth of the map
 137  */
 138 static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
 139 {
 140         /*
 141          * If the shared tag map isn't already initialized, do it now.
 142          * This saves callers from having to check ->bqt when setting up
 143          * devices on the shared host (for libata)
 144          */
 145         if (!shost->bqt) {
 146                 shost->bqt = blk_init_tags(depth);
 147                 if (!shost->bqt)
 148                         return -ENOMEM;
 149         }
 150
 151         return 0;
 152 }
 153
 154 /**
 155  * scsi_host_find_tag - find the tagged command by host
 156  * @shost:      pointer to scsi_host
 157  * @tag:        tag of the scsi_cmnd
 158  *
 159  * Notes:
 160  *      Only works with tags allocated by the generic blk layer.
 161  **/
 162 static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
 163                                                 int tag)
 164 {
 165         struct request *req;
 166
 167         if (tag != SCSI_NO_TAG) {
 168                 req = blk_map_queue_find_tag(shost->bqt, tag);
 169                 return req ? (struct scsi_cmnd *)req->special : NULL;
 170         }
 171         return NULL;
 172 }
 173
 174 #endif /* CONFIG_BLOCK */
 175 #endif /* _SCSI_SCSI_TCQ_H */