/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPIBSG_H
#define _UAPIBSG_H

#ifdef __KERNEL__
#include <linux/build_bug.h>
#endif /* __KERNEL__ */
#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 flag constants below:
 * sg.h sg_io_hdr also has bits defined for it's flags member. These
 * two flag values (0x10 and 0x20) have the same meaning in sg.h . For
 * bsg the BSG_FLAG_Q_AT_HEAD flag is ignored since it is the deafult.
 */
#define BSG_FLAG_Q_AT_TAIL 0x10 /* default is Q_AT_HEAD */
#define BSG_FLAG_Q_AT_HEAD 0x20

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;
};

struct bsg_uring_cmd {
        __u64 request;          /* [i], [*i] command descriptor address */
        __u32 request_len;      /* [i] command descriptor length in bytes */
        __u32 protocol;         /* [i] protocol type (BSG_PROTOCOL_*) */
        __u32 subprotocol;      /* [i] subprotocol type (BSG_SUB_PROTOCOL_*) */
        __u32 max_response_len; /* [i] response buffer size in bytes */

        __u64 response;         /* [i], [*o] response data address */
        __u64 dout_xferp;       /* [i], [*i] */
        __u32 dout_xfer_len;    /* [i] bytes to be transferred to device */
        __u32 dout_iovec_count; /* [i] 0 -> "flat" dout transfer else
                                 * dout_xferp points to array of iovec
                                 */
        __u64 din_xferp;        /* [i], [*o] */
        __u32 din_xfer_len;     /* [i] bytes to be transferred from device */
        __u32 din_iovec_count;  /* [i] 0 -> "flat" din transfer */

        __u32 timeout_ms;       /* [i] timeout in milliseconds */
        __u8  reserved[12];     /* reserved for future extension */
};

#ifdef __KERNEL__
/* Must match IORING_OP_URING_CMD payload size (e.g. SQE128). */
static_assert(sizeof(struct bsg_uring_cmd) == 80);
#endif /* __KERNEL__ */


/*
 * SCSI BSG io_uring completion (res2, 64-bit)
 *
 * When using BSG_PROTOCOL_SCSI + BSG_SUB_PROTOCOL_SCSI_CMD with
 * IORING_OP_URING_CMD, the completion queue entry (CQE) contains:
 *   - result: errno (0 on success)
 *   - res2: packed SCSI status
 *
 * res2 bit layout:
 *   [0..7]   device_status  (SCSI status byte, e.g. CHECK_CONDITION)
 *   [8..15]  driver_status  (e.g. DRIVER_SENSE when sense data is valid)
 *   [16..23] host_status    (e.g. DID_OK, DID_TIME_OUT)
 *   [24..31] sense_len_wr   (bytes of sense data written to response buffer)
 *   [32..63] resid_len      (residual transfer length)
 */
static inline __u8 bsg_scsi_res2_device_status(__u64 res2)
{
        return res2 & 0xff;
}
static inline __u8 bsg_scsi_res2_driver_status(__u64 res2)
{
        return res2 >> 8;
}
static inline __u8 bsg_scsi_res2_host_status(__u64 res2)
{
        return res2 >> 16;
}
static inline __u8 bsg_scsi_res2_sense_len(__u64 res2)
{
        return res2 >> 24;
}
static inline __u32 bsg_scsi_res2_resid_len(__u64 res2)
{
        return res2 >> 32;
}
static inline __u64 bsg_scsi_res2_build(__u8 device_status, __u8 driver_status,
                                        __u8 host_status, __u8 sense_len_wr,
                                        __u32 resid_len)
{
        return ((__u64)(__u32)(resid_len) << 32) |
                ((__u64)sense_len_wr << 24) |
                ((__u64)host_status << 16) |
                ((__u64)driver_status << 8) |
                (__u64)device_status;
}

#endif /* _UAPIBSG_H */