LXR linux/include/scsi/scsi

   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 */
  26static 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
  37static 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 **/
  64static 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 **/
  80static 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 **/
  97static 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 **/
 118static 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 */
 137static 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 **/
 161static 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 */
 175