minix/drivers/storage/virtio_blk/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 #if 0
  29 #include <linux/types.h>
  30 #include <linux/virtio_ids.h>
  31 #include <linux/virtio_config.h>
  32 #endif
  33
  34 /* Feature bits */
  35 #define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
  36 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
  37 #define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
  38 #define VIRTIO_BLK_F_GEOMETRY   4       /* Legacy geometry available  */
  39 #define VIRTIO_BLK_F_RO         5       /* Disk is read-only */
  40 #define VIRTIO_BLK_F_BLK_SIZE   6       /* Block size of disk is available*/
  41 #define VIRTIO_BLK_F_SCSI       7       /* Supports scsi command passthru */
  42 #define VIRTIO_BLK_F_FLUSH      9       /* Cache flush command support */
  43 #define VIRTIO_BLK_F_TOPOLOGY   10      /* Topology information is available */
  44
  45 #define VIRTIO_BLK_ID_BYTES     20      /* ID string length */
  46
  47 struct virtio_blk_config {
  48         /* The capacity (in 512-byte sectors). */
  49         u64_t capacity;
  50         /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  51         u32_t size_max;
  52         /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  53         u32_t seg_max;
  54         /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
  55         struct virtio_blk_geometry {
  56                 u16_t cylinders;
  57                 u8_t heads;
  58                 u8_t sectors;
  59         } geometry;
  60
  61         /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  62         u32_t blk_size;
  63
  64         /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
  65         /* exponent for physical block per logical block. */
  66         u8_t physical_block_exp;
  67         /* alignment offset in logical blocks. */
  68         u8_t alignment_offset;
  69         /* minimum I/O size without performance penalty in logical blocks. */
  70         u16_t min_io_size;
  71         /* optimal sustained I/O size in logical blocks. */
  72         u32_t opt_io_size;
  73
  74 } __attribute__((packed));
  75
  76 /*
  77  * Command types
  78  *
  79  * Usage is a bit tricky as some bits are used as flags and some are not.
  80  *
  81  * Rules:
  82  *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  83  *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
  84  *   and may not be combined with any of the other flags.
  85  */
  86
  87 /* These two define direction. */
  88 #define VIRTIO_BLK_T_IN         0
  89 #define VIRTIO_BLK_T_OUT        1
  90
  91 /* This bit says it's a scsi command, not an actual read or write. */
  92 #define VIRTIO_BLK_T_SCSI_CMD   2
  93
  94 /* Cache flush command */
  95 #define VIRTIO_BLK_T_FLUSH      4
  96
  97 /* Get device ID command */
  98 #define VIRTIO_BLK_T_GET_ID    8
  99
 100 /* Barrier before this op. */
 101 #define VIRTIO_BLK_T_BARRIER    0x80000000
 102
 103 /* This is the first element of the read scatter-gather list. */
 104 struct virtio_blk_outhdr {
 105         /* VIRTIO_BLK_T* */
 106         u32_t type;
 107         /* io priority. */
 108         u32_t ioprio;
 109         /* Sector (ie. 512 byte offset) */
 110         u64_t sector;
 111 };
 112
 113 struct virtio_scsi_inhdr {
 114         u32_t errors;
 115         u32_t data_len;
 116         u32_t sense_len;
 117         u32_t residual;
 118 };
 119
 120 /* And this is the final byte of the write scatter-gather list. */
 121 #define VIRTIO_BLK_S_OK         0
 122 #define VIRTIO_BLK_S_IOERR      1
 123 #define VIRTIO_BLK_S_UNSUPP     2
 124 #endif /* _LINUX_VIRTIO_BLK_H */