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#ifndef _SCSI_SCSI_TCQ_H
#define _SCSI_SCSI_TCQ_H
#include <linux/blkdev.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#define MSG_SIMPLE_TAG 0x20
#define MSG_HEAD_TAG 0x21
#define MSG_ORDERED_TAG 0x22
#define SCSI_NO_TAG (-1) /* identify no tag in use */
/**
* scsi_get_tag_type - get the type of tag the device supports
* @sdev: the scsi device
*
* Notes:
* If the drive only supports simple tags, returns MSG_SIMPLE_TAG
* if it supports all tag types, returns MSG_ORDERED_TAG.
*/
static inline int scsi_get_tag_type(struct scsi_device *sdev)
{
if (!sdev->tagged_supported)
return 0;
if (sdev->ordered_tags)
return MSG_ORDERED_TAG;
if (sdev->simple_tags)
return MSG_SIMPLE_TAG;
return 0;
}
static inline void scsi_set_tag_type(struct scsi_device *sdev, int tag)
{
switch (tag) {
case MSG_ORDERED_TAG:
sdev->ordered_tags = 1;
/* fall through */
case MSG_SIMPLE_TAG:
sdev->simple_tags = 1;
break;
case 0:
/* fall through */
default:
sdev->ordered_tags = 0;
sdev->simple_tags = 0;
break;
}
}
/**
* scsi_activate_tcq - turn on tag command queueing
* @SDpnt: device to turn on TCQ for
* @depth: queue depth
*
* Notes:
* Eventually, I hope depth would be the maximum depth
* the device could cope with and the real queue depth
* would be adjustable from 0 to depth.
**/
static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
{
if (!sdev->tagged_supported)
return;
if (!blk_queue_tagged(sdev->request_queue))
blk_queue_init_tags(sdev->request_queue, depth, NULL);
scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
}
/**
* scsi_deactivate_tcq - turn off tag command queueing
* @SDpnt: device to turn off TCQ for
**/
static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
{
if (blk_queue_tagged(sdev->request_queue))
blk_queue_free_tags(sdev->request_queue);
scsi_adjust_queue_depth(sdev, 0, depth);
}
/**
* scsi_populate_tag_msg - place a tag message in a buffer
* @SCpnt: pointer to the Scsi_Cmnd for the tag
* @msg: pointer to the area to place the tag
*
* Notes:
* designed to create the correct type of tag message for the
* particular request. Returns the size of the tag message.
* May return 0 if TCQ is disabled for this device.
**/
static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
{
struct request *req = cmd->request;
struct scsi_device *sdev = cmd->device;
if (blk_rq_tagged(req)) {
if (sdev->ordered_tags && req->flags & REQ_HARDBARRIER)
*msg++ = MSG_ORDERED_TAG;
else
*msg++ = MSG_SIMPLE_TAG;
*msg++ = req->tag;
return 2;
}
return 0;
}
/**
* scsi_find_tag - find a tagged command by device
* @SDpnt: pointer to the ScSI device
* @tag: the tag number
*
* Notes:
* Only works with tags allocated by the generic blk layer.
**/
static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
{
struct request *req;
if (tag != SCSI_NO_TAG) {
req = blk_queue_find_tag(sdev->request_queue, tag);
return req ? (struct scsi_cmnd *)req->special : NULL;
}
/* single command, look in space */
return sdev->current_cmnd;
}
#endif /* _SCSI_SCSI_TCQ_H */
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