include/uapi/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_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
  51 struct 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. */
 110 struct 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
 119 struct 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 */