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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#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 */
25static 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
36static 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 **/
63static 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 **/
78static 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 **/
95static 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 **/
120static 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 */