include/linux/virtio_blk.h

   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_FLUSH      9       /* Cache flush command support */
  41 #define VIRTIO_BLK_F_TOPOLOGY   10      /* Topology information is available */
  42
  43 #define VIRTIO_BLK_ID_BYTES     20      /* ID string length */
  44
  45 struct virtio_blk_config {
  46         /* The capacity (in 512-byte sectors). */
  47         __u64 capacity;
  48         /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  49         __u32 size_max;
  50         /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  51         __u32 seg_max;
  52         /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
  53         struct virtio_blk_geometry {
  54                 __u16 cylinders;
  55                 __u8 heads;
  56                 __u8 sectors;
  57         } geometry;
  58
  59         /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  60         __u32 blk_size;
  61
  62         /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
  63         /* exponent for physical block per logical block. */
  64         __u8 physical_block_exp;
  65         /* alignment offset in logical blocks. */
  66         __u8 alignment_offset;
  67         /* minimum I/O size without performance penalty in logical blocks. */
  68         __u16 min_io_size;
  69         /* optimal sustained I/O size in logical blocks. */
  70         __u32 opt_io_size;
  71
  72 } __attribute__((packed));
  73
  74 /*
  75  * Command types
  76  *
  77  * Usage is a bit tricky as some bits are used as flags and some are not.
  78  *
  79  * Rules:
  80  *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  81  *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
  82  *   and may not be combined with any of the other flags.
  83  */
  84
  85 /* These two define direction. */
  86 #define VIRTIO_BLK_T_IN         0
  87 #define VIRTIO_BLK_T_OUT        1
  88
  89 /* This bit says it's a scsi command, not an actual read or write. */
  90 #define VIRTIO_BLK_T_SCSI_CMD   2
  91
  92 /* Cache flush command */
  93 #define VIRTIO_BLK_T_FLUSH      4
  94
  95 /* Get device ID command */
  96 #define VIRTIO_BLK_T_GET_ID    8
  97
  98 /* Barrier before this op. */
  99 #define VIRTIO_BLK_T_BARRIER    0x80000000
 100
 101 /* This is the first element of the read scatter-gather list. */
 102 struct virtio_blk_outhdr {
 103         /* VIRTIO_BLK_T* */
 104         __u32 type;
 105         /* io priority. */
 106         __u32 ioprio;
 107         /* Sector (ie. 512 byte offset) */
 108         __u64 sector;
 109 };
 110
 111 struct virtio_scsi_inhdr {
 112         __u32 errors;
 113         __u32 data_len;
 114         __u32 sense_len;
 115         __u32 residual;
 116 };
 117
 118 /* And this is the final byte of the write scatter-gather list. */
 119 #define VIRTIO_BLK_S_OK         0
 120 #define VIRTIO_BLK_S_IOERR      1
 121 #define VIRTIO_BLK_S_UNSUPP     2
 122 #endif /* _LINUX_VIRTIO_BLK_H */