linux/include/linux/virtio_blk.h
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   1#ifndef _LINUX_VIRTIO_BLK_H
   2#define _LINUX_VIRTIO_BLK_H
   3/* This header is BSD licensed so anyone can use the definitions to implement
   4 * compatible drivers/servers.
   5 *
   6 * Redistribution and use in source and binary forms, with or without
   7 * modification, are permitted provided that the following conditions
   8 * are met:
   9 * 1. Redistributions of source code must retain the above copyright
  10 *    notice, this list of conditions and the following disclaimer.
  11 * 2. Redistributions in binary form must reproduce the above copyright
  12 *    notice, this list of conditions and the following disclaimer in the
  13 *    documentation and/or other materials provided with the distribution.
  14 * 3. Neither the name of IBM nor the names of its contributors
  15 *    may be used to endorse or promote products derived from this software
  16 *    without specific prior written permission.
  17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
  18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20 * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
  21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27 * SUCH DAMAGE. */
  28#include <linux/types.h>
  29#include <linux/virtio_ids.h>
  30#include <linux/virtio_config.h>
  31
  32/* Feature bits */
  33#define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
  34#define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
  35#define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
  36#define VIRTIO_BLK_F_GEOMETRY   4       /* Legacy geometry available  */
  37#define VIRTIO_BLK_F_RO         5       /* Disk is read-only */
  38#define VIRTIO_BLK_F_BLK_SIZE   6       /* Block size of disk is available*/
  39#define VIRTIO_BLK_F_SCSI       7       /* Supports scsi command passthru */
  40#define VIRTIO_BLK_F_WCE        9       /* Writeback mode enabled after reset */
  41#define VIRTIO_BLK_F_TOPOLOGY   10      /* Topology information is available */
  42#define VIRTIO_BLK_F_CONFIG_WCE 11      /* Writeback mode available in config */
  43
  44#ifndef __KERNEL__
  45/* Old (deprecated) name for VIRTIO_BLK_F_WCE. */
  46#define VIRTIO_BLK_F_FLUSH VIRTIO_BLK_F_WCE
  47#endif
  48
  49#define VIRTIO_BLK_ID_BYTES     20      /* ID string length */
  50
  51struct virtio_blk_config {
  52        /* The capacity (in 512-byte sectors). */
  53        __u64 capacity;
  54        /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  55        __u32 size_max;
  56        /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  57        __u32 seg_max;
  58        /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
  59        struct virtio_blk_geometry {
  60                __u16 cylinders;
  61                __u8 heads;
  62                __u8 sectors;
  63        } geometry;
  64
  65        /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  66        __u32 blk_size;
  67
  68        /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
  69        /* exponent for physical block per logical block. */
  70        __u8 physical_block_exp;
  71        /* alignment offset in logical blocks. */
  72        __u8 alignment_offset;
  73        /* minimum I/O size without performance penalty in logical blocks. */
  74        __u16 min_io_size;
  75        /* optimal sustained I/O size in logical blocks. */
  76        __u32 opt_io_size;
  77
  78        /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
  79        __u8 wce;
  80} __attribute__((packed));
  81
  82/*
  83 * Command types
  84 *
  85 * Usage is a bit tricky as some bits are used as flags and some are not.
  86 *
  87 * Rules:
  88 *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  89 *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
  90 *   and may not be combined with any of the other flags.
  91 */
  92
  93/* These two define direction. */
  94#define VIRTIO_BLK_T_IN         0
  95#define VIRTIO_BLK_T_OUT        1
  96
  97/* This bit says it's a scsi command, not an actual read or write. */
  98#define VIRTIO_BLK_T_SCSI_CMD   2
  99
 100/* Cache flush command */
 101#define VIRTIO_BLK_T_FLUSH      4
 102
 103/* Get device ID command */
 104#define VIRTIO_BLK_T_GET_ID    8
 105
 106/* Barrier before this op. */
 107#define VIRTIO_BLK_T_BARRIER    0x80000000
 108
 109/* This is the first element of the read scatter-gather list. */
 110struct virtio_blk_outhdr {
 111        /* VIRTIO_BLK_T* */
 112        __u32 type;
 113        /* io priority. */
 114        __u32 ioprio;
 115        /* Sector (ie. 512 byte offset) */
 116        __u64 sector;
 117};
 118
 119struct virtio_scsi_inhdr {
 120        __u32 errors;
 121        __u32 data_len;
 122        __u32 sense_len;
 123        __u32 residual;
 124};
 125
 126/* And this is the final byte of the write scatter-gather list. */
 127#define VIRTIO_BLK_S_OK         0
 128#define VIRTIO_BLK_S_IOERR      1
 129#define VIRTIO_BLK_S_UNSUPP     2
 130#endif /* _LINUX_VIRTIO_BLK_H */
 131
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