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 #include <linux/types.h>
   6 #include <linux/virtio_ids.h>
   7 #include <linux/virtio_config.h>
   8
   9 /* Feature bits */
  10 #define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
  11 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
  12 #define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
  13 #define VIRTIO_BLK_F_GEOMETRY   4       /* Legacy geometry available  */
  14 #define VIRTIO_BLK_F_RO         5       /* Disk is read-only */
  15 #define VIRTIO_BLK_F_BLK_SIZE   6       /* Block size of disk is available*/
  16 #define VIRTIO_BLK_F_SCSI       7       /* Supports scsi command passthru */
  17 #define VIRTIO_BLK_F_FLUSH      9       /* Cache flush command support */
  18 #define VIRTIO_BLK_F_TOPOLOGY   10      /* Topology information is available */
  19
  20 #define VIRTIO_BLK_ID_BYTES     20      /* ID string length */
  21
  22 struct virtio_blk_config {
  23         /* The capacity (in 512-byte sectors). */
  24         __u64 capacity;
  25         /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  26         __u32 size_max;
  27         /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  28         __u32 seg_max;
  29         /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
  30         struct virtio_blk_geometry {
  31                 __u16 cylinders;
  32                 __u8 heads;
  33                 __u8 sectors;
  34         } geometry;
  35
  36         /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  37         __u32 blk_size;
  38
  39         /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
  40         /* exponent for physical block per logical block. */
  41         __u8 physical_block_exp;
  42         /* alignment offset in logical blocks. */
  43         __u8 alignment_offset;
  44         /* minimum I/O size without performance penalty in logical blocks. */
  45         __u16 min_io_size;
  46         /* optimal sustained I/O size in logical blocks. */
  47         __u32 opt_io_size;
  48
  49 } __attribute__((packed));
  50
  51 /*
  52  * Command types
  53  *
  54  * Usage is a bit tricky as some bits are used as flags and some are not.
  55  *
  56  * Rules:
  57  *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  58  *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
  59  *   and may not be combined with any of the other flags.
  60  */
  61
  62 /* These two define direction. */
  63 #define VIRTIO_BLK_T_IN         0
  64 #define VIRTIO_BLK_T_OUT        1
  65
  66 /* This bit says it's a scsi command, not an actual read or write. */
  67 #define VIRTIO_BLK_T_SCSI_CMD   2
  68
  69 /* Cache flush command */
  70 #define VIRTIO_BLK_T_FLUSH      4
  71
  72 /* Get device ID command */
  73 #define VIRTIO_BLK_T_GET_ID    8
  74
  75 /* Barrier before this op. */
  76 #define VIRTIO_BLK_T_BARRIER    0x80000000
  77
  78 /* This is the first element of the read scatter-gather list. */
  79 struct virtio_blk_outhdr {
  80         /* VIRTIO_BLK_T* */
  81         __u32 type;
  82         /* io priority. */
  83         __u32 ioprio;
  84         /* Sector (ie. 512 byte offset) */
  85         __u64 sector;
  86 };
  87
  88 struct virtio_scsi_inhdr {
  89         __u32 errors;
  90         __u32 data_len;
  91         __u32 sense_len;
  92         __u32 residual;
  93 };
  94
  95 /* And this is the final byte of the write scatter-gather list. */
  96 #define VIRTIO_BLK_S_OK         0
  97 #define VIRTIO_BLK_S_IOERR      1
  98 #define VIRTIO_BLK_S_UNSUPP     2
  99 #endif /* _LINUX_VIRTIO_BLK_H */