1. 根目录:
2. include
3. uapi
4. linux
5. bsg.h

#ifndef _UAPIBSG_H
#define _UAPIBSG_H

#include <linux/types.h>

#define BSG_PROTOCOL_SCSI		0

#define BSG_SUB_PROTOCOL_SCSI_CMD	0
#define BSG_SUB_PROTOCOL_SCSI_TMF	1
#define BSG_SUB_PROTOCOL_SCSI_TRANSPORT	2

/*
 * For flags member below
 * sg.h sg_io_hdr also has bits defined for it's flags member. However
 * none of these bits are implemented/used by bsg. The bits below are
 * allocated to not conflict with sg.h ones anyway.
 */
#define BSG_FLAG_Q_AT_TAIL 0x10 /* default, == 0 at this bit, is Q_AT_HEAD */

struct sg_io_v4 {
	__s32 guard;		/* [i] 'Q' to differentiate from v3 */
	__u32 protocol;		/* [i] 0 -> SCSI , .... */
	__u32 subprotocol;	/* [i] 0 -> SCSI command, 1 -> SCSI task
				   management function, .... */

	__u32 request_len;	/* [i] in bytes */
	__u64 request;		/* [i], [*i] {SCSI: cdb} */
	__u64 request_tag;	/* [i] {SCSI: task tag (only if flagged)} */
	__u32 request_attr;	/* [i] {SCSI: task attribute} */
	__u32 request_priority;	/* [i] {SCSI: task priority} */
	__u32 request_extra;	/* [i] {spare, for padding} */
	__u32 max_response_len;	/* [i] in bytes */
	__u64 response;		/* [i], [*o] {SCSI: (auto)sense data} */

        /* "dout_": data out (to device); "din_": data in (from device) */
	__u32 dout_iovec_count;	/* [i] 0 -> "flat" dout transfer else
				   dout_xfer points to array of iovec */
	__u32 dout_xfer_len;	/* [i] bytes to be transferred to device */
	__u32 din_iovec_count;	/* [i] 0 -> "flat" din transfer */
	__u32 din_xfer_len;	/* [i] bytes to be transferred from device */
	__u64 dout_xferp;	/* [i], [*i] */
	__u64 din_xferp;	/* [i], [*o] */

	__u32 timeout;		/* [i] units: millisecond */
	__u32 flags;		/* [i] bit mask */
	__u64 usr_ptr;		/* [i->o] unused internally */
	__u32 spare_in;		/* [i] */

	__u32 driver_status;	/* [o] 0 -> ok */
	__u32 transport_status;	/* [o] 0 -> ok */
	__u32 device_status;	/* [o] {SCSI: command completion status} */
	__u32 retry_delay;	/* [o] {SCSI: status auxiliary information} */
	__u32 info;		/* [o] additional information */
	__u32 duration;		/* [o] time to complete, in milliseconds */
	__u32 response_len;	/* [o] bytes of response actually written */
	__s32 din_resid;	/* [o] din_xfer_len - actual_din_xfer_len */
	__s32 dout_resid;	/* [o] dout_xfer_len - actual_dout_xfer_len */
	__u64 generated_tag;	/* [o] {SCSI: transport generated task tag} */
	__u32 spare_out;	/* [o] */

	__u32 padding;
};


#endif /* _UAPIBSG_H */