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	struct scsi_device *sdev = cmd->device;
101
102        if (blk_rq_tagged(req)) {
103		if (sdev->ordered_tags && req->cmd_flags & REQ_HARDBARRIER)
104        	        *msg++ = MSG_ORDERED_TAG;
105        	else
106        	        *msg++ = MSG_SIMPLE_TAG;
107        	*msg++ = req->tag;
108        	return 2;
109	}
110
111	return 0;
112}
113
114/**
115 * scsi_find_tag - find a tagged command by device
116 * @SDpnt:	pointer to the ScSI device
117 * @tag:	the tag number
118 *
119 * Notes:
120 *	Only works with tags allocated by the generic blk layer.
121 **/
122static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
123{
124
125        struct request *req;
126
127        if (tag != SCSI_NO_TAG) {
128        	req = blk_queue_find_tag(sdev->request_queue, tag);
129	        return req ? (struct scsi_cmnd *)req->special : NULL;
130	}
131
132	/* single command, look in space */
133	return sdev->current_cmnd;
134}
135
136/**
137 * scsi_init_shared_tag_map - create a shared tag map
138 * @shost:	the host to share the tag map among all devices
139 * @depth:	the total depth of the map
140 */
141static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
142{
143	shost->bqt = blk_init_tags(depth);
144	return shost->bqt ? 0 : -ENOMEM;
145}
146
147/**
148 * scsi_host_find_tag - find the tagged command by host
149 * @shost:	pointer to scsi_host
150 * @tag:	tag of the scsi_cmnd
151 *
152 * Notes:
153 *	Only works with tags allocated by the generic blk layer.
154 **/
155static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
156						int tag)
157{
158	struct request *req;
159
160	if (tag != SCSI_NO_TAG) {
161		req = blk_map_queue_find_tag(shost->bqt, tag);
162		return req ? (struct scsi_cmnd *)req->special : NULL;
163	}
164	return NULL;
165}
166
167#endif /* CONFIG_BLOCK */
168#endif /* _SCSI_SCSI_TCQ_H */
169