tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 */
27static 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
38static 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 **/
65static 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 **/
81static 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 **/
98static 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 **/
119static 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 */
138static 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 **/
162static 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 */